Electrode assembly, battery, battery pack including the same, and automobile

Abstract

To provide an electrode assembly having an improved uncoated portion structure capable of reducing stress applied to the uncoated portions exposed at both ends of the electrode assembly when the uncoated portions are bent.SOLUTION: The present invention discloses an electrode assembly, a battery, a battery pack, and an automobile. The electrode assembly includes a first electrode, a second electrode, and a separator interposed therebetween, wound around a winding shaft to define a core and an outer circumferential surface. The first electrode includes a first active material portion coated with an active material layer along the winding direction, and a first uncoated portion not coated with an active material layer. At least a portion of the first uncoated portion is itself defined as an electrode tab. The first uncoated portion includes a first portion adjacent to the core of the electrode assembly, a second portion adjacent to the outer circumferential surface of the electrode assembly, and a third portion between the first and second portions. In the winding shaft direction, the first portion or the second portion has a height lower than the third portion.SELECTED DRAWING: Figure 7a

Description

[Technical Field]

[0001] The present invention relates to an electrode assembly, a battery, and a battery pack and a vehicle including the same.

[0002] This application is a Korean Patent Application No. 10-2021-0007278 filed on January 19, 2021, Korean Patent Application No. 10-2021-0022897 filed on February 19, 2021, Korean Patent Application No. 10-2021-0022894 filed on February 19, 2021, Korean Patent Application No. 10-2021-0022891 filed on February 19, 2021, Korean Patent Application No. 10-2021-0022881 filed on February 23, 2021, Korean Patent Application No. 10-2021-0024424 filed on March 31, 2021 Korean Patent Application No. 10-2021-0030300 filed on March 8, 2021, Korean Patent Application No. 10-2021-0030291 filed on March 8, 2021, Korean Patent Application No. 10-2021-0046798 filed on April 9, 2021, Korean Patent Application No. 10-2021-0058183 filed on May 4, 2021, Korean Patent Application No. 10-2021-0077046 filed on June 14, 2021, Korean Patent Application No. 10-2021-0084326 filed on June 28, 2021, Korean Patent Application No. 10-2021-0084326 filed on October 1, 2021 10-2021-0131225, Korean Patent Application No. 10-2021-0131215 filed on October 1, 2021, Korean Patent Application No. 10-2021-0131205 filed on October 1, 2021, Korean Patent Application No. 10-2021-0131208 filed on October 1, 2021, Korean Patent Application No. 10-2021-0131207 filed on October 14, 2021, Korean Patent Application No. 10-2021-0137001 filed on October 15, 2021 137856, Korean Patent Application No. 10-2021-0142196 filed on October 22, 2021, Korean Patent Application No. 10-2021-0153472 filed on November 9, 2021, Korean Patent Application No. 10-2021-0160823 filed on November 19, 2021, Korean Patent Application No. 10-2021-0163809 filed on November 24, 2021, Korean Patent Application No. 10-2021-0165866 filed on November 26, 2021, Korean Patent Application No. 10-2021-0172446 filed on December 3, 2021,Korean Patent Application No. 10-2021-0177091 filed on December 10, 2021, Korean Patent Application No. 10-2021-0194593 filed on December 31, 2021, Korean Patent Application No. 10-2021-0194610 filed on December 31, 2021, Korean Patent Application No. 10-2021-0194572 filed on December 31, 2021, Priority is claimed based on Korean Patent Application No. 10-2021-0194612 filed on December 31, 2021, Korean Patent Application No. 10-2021-0194611 filed on December 31, 2021, and Korean Patent Application No. 10-2022-0001802 filed on January 5, 2022, and the contents disclosed in the specifications and drawings of those applications are incorporated herein in their entirety. [Background technology]

[0003] Secondary batteries, which have high applicability to each product group and electrical properties such as high energy density, are widely used not only in portable devices but also in electric vehicles (EVs) and hybrid electric vehicles (HEVs) that are driven by electrical sources.

[0004] These secondary batteries not only have the primary advantage of dramatically reducing the use of fossil fuels, but are also environmentally friendly as they do not produce any by-products from energy use, and are attracting attention as a new energy source for improving energy efficiency.

[0005] Currently, secondary batteries such as lithium ion batteries, lithium polymer batteries, nickel cadmium batteries, nickel metal hydride batteries, and nickel zinc batteries are widely used. The operating voltage of such unit secondary batteries, i.e., unit batteries, is approximately 2.5V to 4.5V. Therefore, if a higher output voltage is required, a battery pack is constructed by connecting multiple batteries in series. Alternatively, a battery pack may be constructed by connecting multiple batteries in parallel depending on the required charge / discharge capacity of the battery pack. Therefore, the number of batteries included in the battery pack and the electrical connection configuration can be variously set depending on the required output voltage and / or charge / discharge capacity.

[0006] Meanwhile, known types of unit secondary batteries include cylindrical, prismatic, and pouch-type batteries. In cylindrical batteries, a separator, an insulator, is interposed between a positive electrode and a negative electrode, which is then wound up to form a jelly-roll-shaped electrode assembly. This assembly is then inserted into a battery housing to complete the battery. The battery housing is referred to in the industry as a battery can. Strip-shaped electrode tabs are connected to the uncoated portions of the positive and negative electrodes, electrically connecting the electrode assembly to the electrode terminals exposed to the outside. For reference, the positive electrode terminal is a sealed cap that seals the opening of the battery housing, and the negative electrode terminal is the battery housing. However, conventional cylindrical batteries with this structure suffer from problems such as high resistance, excessive heat generation, and poor current collection efficiency due to current concentration at the strip-shaped electrode tabs connected to the uncoated portions of the positive and / or negative electrodes.

[0007] Resistance and heat generation are not a major issue for small cylindrical batteries with form factors such as 1865 (diameter: 18mm, height: 65mm) and 2170 (diameter: 21mm, height: 70mm). However, when the form factor of cylindrical batteries is increased to be used in electric vehicles, a large amount of heat is generated around the electrode tabs during the fast charging process, which can cause the cylindrical battery to catch fire.

[0008] To solve this problem, a cylindrical battery (so-called tab-less cylindrical battery) has been proposed, which has a structure in which positive and negative electrode uncoated areas are located at the top and bottom of a jelly-roll type electrode assembly, respectively, and current collectors are welded to these uncoated areas to improve current collection efficiency.

[0009] Figures 1 to 3 show the manufacturing process of a tabless cylindrical battery. Figure 1 shows the structure of the electrode, Figure 2 shows the electrode winding process, and Figure 3 shows the process of welding a current collector to the folded surface area of the uncoated portion.

[0010] 1 to 3, the positive electrode 10 and the negative electrode 11 have a structure in which an active material 21 is coated on a sheet-shaped current collector 20, and include a non-coating portion 22 on one long side along the winding direction X. The long side refers to the side that is parallel to the x-axis direction and has a relatively long length.

[0011] The electrode assembly A is fabricated by sequentially stacking a positive electrode 10 and a negative electrode 11 together with two separators 12 as shown in Figure 2, and then winding the stack in one direction (X-axis direction). At this time, the uncoated portion of the positive electrode 10 and the uncoated portion of the negative electrode 11 are arranged in opposite directions.

[0012] After the winding process, the uncoated portion 10a of the positive electrode 10 and the uncoated portion 11a of the negative electrode 11 are folded toward the core, and then the current collectors 30 and 31 are welded to the uncoated portions 10a and 11a, respectively.

[0013] No separate electrode tabs are attached to the positive electrode uncoated region 10a and the negative electrode uncoated region 11a, and current collectors 30 and 31 are connected to external electrode terminals, forming a current path with a large cross-sectional area along the winding axis direction of electrode assembly A (see arrow), which has the advantage of reducing battery resistance, since resistance is inversely proportional to the cross-sectional area of the path through which current flows.

[0014] In a tabless cylindrical battery, in order to improve the welding characteristics between the uncoated portions 10a, 11a and the current collectors 30, 31, strong pressure must be applied to the welding areas of the uncoated portions 10a, 11a to bend them as flat as possible.

[0015] However, when the welded regions of the non-coated portions 10a, 11a are bent, the patterns of the non-coated portions 10a, 11a may become irregularly distorted and deformed. This may result in contact with the electrode of the opposite polarity, causing an internal short circuit, or microcracks in the non-coated portions 10a, 11a. Furthermore, as the non-coated portion 32 adjacent to the core of the electrode assembly A is bent, it may completely or partially block the cavity 33 in the core of the electrode assembly A. This may cause problems during the electrolyte injection process. The cavity 33 in the core of the electrode assembly A serves as a passage through which the electrolyte is injected. However, if this passage is blocked, it is difficult to inject the electrolyte. Furthermore, when the electrolyte injector is inserted into the cavity 33, it may interfere with the non-coated portion 32 near the core, resulting in tearing of the non-coated portion 32.

[0016] In addition, the bent portions of the plain portions 10a and 11a where the current collectors 30 and 31 are welded must be overlapped with no open spaces (gaps), which ensures sufficient welding strength and prevents the laser from penetrating into the electrode assembly A and melting the separator or active material when using cutting-edge technology such as laser welding.

[0017] On the other hand, in a conventional table-less cylindrical battery, a positive electrode uncoated area 10a is formed over the entire top of the electrode assembly A. Therefore, when the outer periphery of the upper end of the battery housing is pressed inward to form a beading portion, the upper edge area 34 of the electrode assembly A is compressed by the battery housing. This compression causes partial deformation of the electrode assembly A, which can tear the separator 12 and cause an internal short circuit. If a short circuit occurs inside the battery, it can cause the battery to overheat or explode. Summary of the Invention [Problem to be solved by the invention]

[0018] The present invention has been made in light of the background of the prior art as described above, and aims to provide an electrode assembly having an improved uncoated portion structure that can alleviate stress applied to the uncoated portions exposed at both ends of the electrode assembly when the uncoated portions are bent.

[0019] Another object of the present invention is to provide an electrode assembly in which the electrolyte injection passage is not blocked even when the non-coating portion is bent.

[0020] Another object of the present invention is to provide an electrode assembly including a structure capable of preventing contact between the upper edge of the electrode assembly and the inner surface of the battery housing when the upper end of the battery housing is beaded.

[0021] Another object of the present invention is to provide an electrode assembly in which the physical properties of the welding area are improved by applying a segment structure to the uncoated portion of the electrode and optimizing the dimensions (width, height, and spacing pitch) of the segments, thereby sufficiently increasing the number of stacked segments in the area used as the welding target area.

[0022] Another object of the present invention is to provide an electrode assembly in which a current collector is welded over a wide area to a folded surface region formed by folding a segment, thereby improving energy density and reducing resistance.

[0023] It is yet another object of the present invention to provide a battery including terminals and current collectors with improved designs for electrical wiring at the top.

[0024] It is yet another object of the present invention to provide a battery including an electrode assembly with an improved structure, a battery pack including the same, and a vehicle including the battery pack.

[0025] The technical problems to be solved by the present invention are not limited to the above-mentioned problems, and other problems will be clearly understood by those skilled in the art from the following description of the invention. [Means for solving the problem]

[0026] To achieve the above object, one aspect of the present invention provides an electrode assembly in which a core and an outer circumferential surface are defined by winding a first electrode, a second electrode, and a separator interposed therebetween around a winding shaft, wherein the first electrode includes a first active material portion coated with an active material layer along the winding direction and a first uncoated portion not coated with an active material layer, at least a portion of the first uncoated portion is itself defined as an electrode tab, and the first uncoated portion includes a first portion adjacent to the core of the electrode assembly, a second portion adjacent to the outer circumferential surface of the electrode assembly, and a third portion between the first and second portions, and the first portion or the second portion has a lower height than the third portion in the winding axis direction.

[0027] In one embodiment, the third portion may be defined as the electrode tab when folded along the radial direction of the electrode assembly.

[0028] In another embodiment, the second portion and the third portion may be defined as the electrode tabs when folded along the radial direction of the electrode assembly.

[0029] Preferably, at least a portion of the third portion may be divided into a plurality of independently bendable segments.

[0030] Preferably, each of the plurality of segments may have the form of a geometric figure in which one or more straight lines, one or more curved lines, or a combination thereof are connected.

[0031] As an example, each of the plurality of segments may have a lower width that is wider than an upper width.

[0032] As another example, each of the plurality of segments may have the same width at the bottom and the same width at the top.

[0033] As yet another example, each of the plurality of segments may decrease in width from bottom to top.

[0034] As yet another example, each of the plurality of segments may decrease and then increase in width from bottom to top.

[0035] As yet another example, each of the plurality of segments may increase and then decrease in width from bottom to top.

[0036] As yet another example, each of the plurality of segments may increase in width from bottom to top and then remain constant.

[0037] As yet another example, each of the plurality of segments may decrease in width from bottom to top and then remain constant.

[0038] Desirably, each of the plurality of segments may have straight or curved sides, or a combination thereof.

[0039] As an example, each of the plurality of segments may have an outwardly convex side or an inwardly convex side.

[0040] As another example, each of the plurality of segments may have a rounded top corner.

[0041] In the present invention, the geometric shapes of the plurality of segments may vary individually, in groups, or in groups of two or more, along a direction parallel to the winding direction.

[0042] Preferably, the lower interior angles of the plurality of segments may increase gradually or stepwise in one direction parallel to the winding direction, individually, in groups, or in units of a plurality of groups.

[0043] In one embodiment, the lower interior angle of the plurality of segments may increase gradually or stepwise within a range of 60° to 85° in one direction parallel to the winding direction, individually, in groups, or in units of multiple groups.

[0044] In yet another embodiment, the lower interior angle of each of the segments belonging to one segment group may be greater than the lower interior angle of each of the segments belonging to a segment group arranged closer to the core than that segment group.

[0045] In yet another embodiment, each of the plurality of segments has a geometric shape in which the width decreases from bottom to top, and a lower interior angle θ of the segment located in a winding turn having a radius r around the core of the electrode assembly may fall within an angle range of the following formula:

[0046]

number

[0047] In yet another embodiment, each of the plurality of segments may have straight or curved sides, or a combination thereof.

[0048] In yet another embodiment, each of the plurality of segments may have an outwardly convex or inwardly convex side.

[0049] In yet another embodiment, each of the plurality of segments may have a rounded top corner.

[0050] Preferably, a cutting groove is interposed between adjacent pieces along the winding direction, and the lower part of the cutting groove may include a bottom portion and rounded portions connecting both ends of the bottom portion to the side edges of the pieces on both sides of the cutting groove.

[0051] In one embodiment, the radius of curvature of the rounded portion may be greater than 0 and equal to or less than 0.1 mm, more preferably 0.01 mm to 0.05 mm.

[0052] In another embodiment, the base may be flat.

[0053] In yet another embodiment, a separation pitch defined as the distance between two points where a line extending from the side edges of two pieces located on both sides of the kerf groove intersects with a line extending from the bottom of the kerf groove may be 0.05 mm to 1.00 mm.

[0054] In yet another embodiment, the plurality of pieces may be made of aluminum foil, and a spacing pitch defined as the distance between two points where a line extending from the side edges of two pieces located on both sides of the cutting groove intersects with a line extending from the bottom of the cutting groove may be 0.5 mm to 1.00 mm.

[0055] In yet another embodiment, the spacing pitch of the plurality of segments may vary along a direction parallel to the winding direction, the spacing pitch being defined as the distance between two points where a line extending from the side edges of two segments located on either side of the cutting groove intersects with a line extending from the bottom of the cutting groove.

[0056] In yet another embodiment, the spacing pitch of the plurality of segments may vary in one direction parallel to the winding direction, in groups or in groups of two or more.

[0057] In yet another embodiment, the bottom of the kerf may be spaced a fixed distance from the active material layer.

[0058] Preferably, the distance between the bottom of the cutting groove and the active material layer is 0.2 mm to 4 mm.

[0059] In one embodiment, the gap between the bottom of the cut groove and the active material layer of the plurality of segments may be substantially uniform or may vary along a direction parallel to the winding direction. In the latter case, the gap between the bottom of the cut groove and the active material layer of the plurality of segments may vary individually, in groups, or in groups of two or more groups along a direction parallel to the winding direction.

[0060] Preferably, the bending regions of the plurality of segments in the radial direction of the electrode assembly may be located within a range of 0 to 1 mm above the lower end of the cutting groove.

[0061] In still another embodiment, the angle of a circular arc formed by the lower end of each of the plurality of segments with respect to the core center of the electrode assembly may be 45° or less.

[0062] Preferably, when the radius of a winding turn including the segment is defined as r and the width of the segment in the winding direction based on the core center of the electrode assembly is defined as D(r), D(r) may satisfy the following formula: 1≦D(r)≦(2×π×r / 360°)×45°

[0063] In yet another embodiment, each of the plurality of segments may have a width D(r) in the winding direction that gradually or stepwise increases as the radius r of the winding turn in which the segment is located increases relative to the core center of the electrode assembly, or vice versa.

[0064] In yet another embodiment, the width D(r) of each of the plurality of segments in the winding direction may gradually or stepwise increase and then gradually or stepwise decrease as the radius r of the winding turn in which the segment is located increases relative to the core center of the electrode assembly, or vice versa.

[0065] In yet another embodiment, each of the plurality of segments may have a substantially identical circumferential angle with respect to the core center of the electrode assembly.

[0066] In yet another embodiment, the widths of the plurality of segments may increase at substantially the same or different rates along a direction parallel to the winding direction of the electrode assembly.

[0067] Preferably, the width of each of the plurality of segments may increase gradually or stepwise within a range of 1 mm to 11 mm as the radius r of the winding turn on which the segment is located increases relative to the core center of the electrode assembly.

[0068] In still another embodiment, the height of at least a partial section of the third portion in the winding axis direction may change gradually or stepwise in one direction parallel to the winding direction.

[0069] Preferably, at least a portion of the third portion may have a height in the winding axis direction that increases gradually or stepwise in one direction parallel to the winding direction.

[0070] Preferably, at least a portion of the third portion may have a height in the winding axis direction that gradually or stepwise increases and then gradually or stepwise decreases in one direction parallel to the winding direction.

[0071] Preferably, the third portion and optionally the second portion are divided into a plurality of regions having different heights along a direction parallel to the winding direction, and the height of the uncoated portion in the plurality of regions may increase stepwise along the direction parallel to the winding direction.

[0072] In one embodiment, the first non-coating portion has a height of a first height h1 to an (N-1)th height h2 along a direction parallel to the winding direction. N-1 (N is a height index and is a natural number greater than or equal to 2) N (h N-1 The height may include a uniform section where the height is maintained uniform (larger than the width of the base).

[0073] Preferably, N is 2 to 30.

[0074] In one embodiment, the height h k (k is a natural number from 1 to N) k The plurality of segments having the same length may be arranged in one or more winding turns.

[0075] In other forms, the height h k (k is a natural number from 1 to N) The starting radius of the winding turn containing the segment is r k When the core of the electrode assembly is defined as k More than 90% of the diameter is not blocked by the bend in the segment located at the center.

[0076] In yet another embodiment, the height h k (k is a natural number from 1 to N) The starting radius of the winding turn containing the segment is r k , the radius of the core is r c Then, the height of the segment h k may satisfy the following formula: 2mm≦h k ≦r k -α×r c (α is 0.90 to 1)

[0077] Preferably, the electrode assembly may include, in sequence along a radial direction based on a cross section along the winding axis, a segment-free section where no segments are present, a height-variable section where the height of the segments varies, and a uniform height section where the height of the segments is uniform, and the plurality of segments may be arranged in the height-variable section and the height-uniform section and may be bent along the radial direction of the electrode assembly to form a bent surface region.

[0078] In one embodiment, the first portion is not divided into segments, and the segment-omitted section may correspond to the first portion.

[0079] In another embodiment, the third portion may be divided into a plurality of independently bendable segments, and the variable height section and the uniform height section may correspond to the third portion.

[0080] In yet another embodiment, the second portion and the third portion may be divided into a plurality of segments that can be bent independently, and the variable height section and the uniform height section may correspond to the second portion and the third portion.

[0081] Preferably, in the variable height section and the uniform height section, the maximum height h max may satisfy the following formula: h max ≦W foil -W scrap,min -W margin,min -W gap (W foil is the width of the current collector foil before the segments are formed; W scrap,min is the width corresponding to the minimum cutting scrap margin when cutting the collector foil to form pieces; W margin,min is the minimum meandering margin of the separation membrane; W gap is the width corresponding to the insulating gap between the edge of the second electrode facing the first electrode with the separator interposed therebetween and the edge of the separator.

[0082] Preferably, the insulating gap W gap When the first electrode is a positive electrode, the thickness may be 0.2 mm to 6 mm.

[0083] Preferably, the insulating gap W gap When the first electrode is a negative electrode, the thickness may be 0.1 mm to 2 mm.

[0084] Preferably, the minimum cutting scrap margin W scrap,min The minimum cutting scrap margin W can be 1.5mm to 8mm depending on the cutting method of the cut pieces. scrap,min can be 0.

[0085] Preferably, the minimum meandering margin W of the separation membrane margin,min can be 0 to 1 mm.

[0086] Preferably, the height of the segment arranged in the height variable section can be increased gradually or stepwise within a range of 2 mm to 10 mm.

[0087] In one embodiment, a ratio of a radial length of the segment-free section to a radius of the electrode assembly excluding the core in a radial direction of the electrode assembly may be 10% to 40%.

[0088] In another embodiment, a ratio of the radial length of the height variable section to the radial lengths of the height variable section and the uniform height section in the radial direction of the electrode assembly may be 1% to 50%.

[0089] In still another embodiment, the ratio of the length of the electrode region corresponding to the segment-omitted section to the entire length of the first electrode may be 1% to 30%.

[0090] In still another embodiment, the ratio of the length of the electrode region corresponding to the height variable section to the entire length of the first electrode may be 1% to 40%.

[0091] In still another embodiment, the ratio of the length of the electrode region corresponding to the uniform height section to the entire length of the first electrode may be 50% to 90%.

[0092] Preferably, the plurality of segments may have at least one of a width in the winding direction and a height in the winding axial direction increased stepwise or continuously in one direction parallel to the winding direction.

[0093] In one embodiment, the plurality of segments may form a plurality of segment groups along a direction parallel to the winding direction of the electrode assembly, and the segments belonging to the same segment group may have substantially the same width in the winding direction and height in the winding axis direction.

[0094] In another embodiment, the plurality of segments may form a plurality of segment groups along a direction parallel to the winding direction of the electrode assembly, and the segments belonging to the same segment group may be substantially identical to each other in at least one selected from the width in the winding direction, the height in the winding axis direction, and the inner angle of the lower part of the segment.

[0095] In yet another embodiment, the plurality of segment groups may have different segment shapes between each group or between two or more groups.

[0096] In yet another embodiment, the plurality of segment groups may have different spacing pitches between the segments in each group or in groups of two or more groups.

[0097] Preferably, the segments belonging to the same segment group may have at least one of a width in the winding direction, a height in the winding axial direction, and a lower interior angle that gradually or stepwise increase in one direction parallel to the winding direction of the electrode assembly.

[0098] In yet another embodiment, the segments belonging to the same segment group may have at least one of the width in the winding direction and the height in the winding direction gradually or stepwise increase and then gradually or stepwise decrease in one direction parallel to the winding direction of the electrode assembly, or vice versa.

[0099] In one embodiment, when the winding direction widths of three adjacent sub-segment groups that are consecutively arranged in one direction parallel to the winding direction of the electrode assembly are W1, W2, and W3, respectively, the combination may include a sub-segment group in which W3 / W2 is smaller than W2 / W1.

[0100] In yet another embodiment, the first portion is not divided into segments, and the first portion is not bent along a radial direction of the electrode assembly.

[0101] In yet another embodiment, the second portion is not divided into segments, and the second portion is not bent along the radial direction of the electrode assembly.

[0102] Preferably, an insulating coating layer may be formed at a boundary between the active material layer and a non-coating region in a section where the bottom of the cut groove and the active material layer are separated.

[0103] In one embodiment, the insulating coating layer may include a polymer resin and an inorganic filler dispersed in the polymer resin.

[0104] In another embodiment, the insulating coating layer may be formed to cover a boundary portion between the active material layer and the first uncoated portion along the winding direction.

[0105] In still another embodiment, the insulating coating layer may be formed to cover the boundary between the active material layer and the first uncoated portion with a width of 0.3 mm to 5 mm along the winding axis direction.

[0106] In still another embodiment, the end of the insulating coating layer may be located within a range of -2 mm to 2 mm along the winding axis direction with respect to the end of the separator.

[0107] Preferably, the insulating coating layer may be exposed to the outside of the separator.

[0108] Preferably, the lower end of the cutting groove and the insulating coating layer may be spaced apart by a distance of 0.5 mm to 2 mm.

[0109] Preferably, the end of the insulating coating layer in the winding axis direction may be located within a range of -2 mm to 2 mm from the lower end of the cutting groove.

[0110] In one embodiment, the distance between the lower end of the cutting groove and the insulating coating layer may be substantially the same or may vary. In the latter case, the distance between the plurality of cut pieces may vary individually, in groups, or in groups of two or more, along a direction parallel to the winding direction.

[0111] Preferably, the distance between the lower end of the cutting groove and the insulating coating layer may vary along a direction parallel to the winding direction.

[0112] For example, the distance between the lower end of the cutting groove and the insulating coating layer may vary in groups or in groups of two or more groups along a direction parallel to the winding direction.

[0113] Preferably, the second electrode includes a second active material part coated with an active material layer along the winding direction, and an end of the second active material part may be located between an upper end and a lower end of the insulating coating layer in the winding axis direction.

[0114] In yet another embodiment, the third portion and optionally the second portion may be divided into a plurality of segments that can be bent independently, and the electrode assembly may include a folded surface region formed by bending the plurality of segments along a radial direction of the electrode assembly.

[0115] Preferably, when the number of segments intersecting a virtual line parallel to the winding axis direction at any radial position of the folded surface region relative to the core center of the electrode assembly is defined as the number of stacked segments at that radial position, the folded surface region may include a uniform stacking number section in which the number of stacked segments is uniform from the core side toward the outer periphery (or in the opposite direction), and a decreasing stacking number section located outside the uniform stacking number section in which the number of stacked segments of the segments decreases toward the outer periphery.

[0116] In one embodiment, the radial lengths of the uniform lamination number section and the reduced lamination number section with respect to the core center of the electrode assembly may correspond to the radial length of a radial section in which a winding turn including the plurality of division segments is located.

[0117] In another embodiment, the electrode assembly may include, sequentially along the radial direction, a segment-free section where no segments are present, a height-variable section where the height of the segments varies, and a uniform height section where the height of the segments is uniform, and the radius at which the uniform stack number section begins relative to the core center of the electrode assembly may correspond to the radius at which the height-variable section begins.

[0118] Preferably, the number of stacked pieces in the uniform stacking section may be 10 to 35.

[0119] In one embodiment, the first electrode may be a positive electrode, and the thickness of the divided pieces in the uniform stacking number section may be 100 μm to 875 μm.

[0120] In another embodiment, the first electrode may be a negative electrode, and the thickness of the divided pieces in the uniform stack number section may be 50 μm to 700 μm.

[0121] In still another embodiment, the ratio of the radial length of the uniform lamination number section to the radial lengths of the uniform lamination number section and the decreasing lamination number section may be 30% to 85%.

[0122] Preferably, the electrode assembly further includes a current collector welded to the bent surface region, and the welded region of the current collector may overlap the uniform lamination number section by at least 50% in the radial direction of the electrode assembly.

[0123] In one embodiment, a region of the welding region of the current collector that does not overlap with the uniform lamination number section in the radial direction of the electrode assembly may overlap with the reduced lamination number section.

[0124] In another embodiment, the peripheral edge of the current collector may be welded to the bent surface region while being disposed on the bent surface region so as to cover the end of the bent portion of the radially outermost portion of the electrode assembly.

[0125] Preferably, the welding strength of the welding area of the current collector is 2 kgf / cm 2 It could be more than that.

[0126] More preferably, the welding strength of the welding area of the current collector is 4 kgf / cm 2 It could be more than that.

[0127] In still another embodiment, the first uncoated portion is made of a metal foil, and the metal foil has an elongation ratio of 1.5% to 3.0% and a tensile strength of 25 kgf / mm 2 ~35kgf / mm 2 It could be.

[0128] Preferably, the metal foil may be an aluminum foil.

[0129] Preferably, the camber length of the first electrode may be less than 20 mm.

[0130] Preferably, in the first active material part, the ratio of the length of the short side parallel to the winding axis direction to the length of the long side parallel to the winding direction of the first active material part may be 1.0% to 4.0%.

[0131] In yet another embodiment, the second portion may have a height that decreases stepwise or gradually from the core side to the outer periphery side of the electrode assembly.

[0132] In yet another embodiment, the second portion and the third portion are divided into a plurality of segments that can be bent independently, and the segments included in the second portion may have at least one of a width in the winding direction and a height in the winding axis direction greater than the segments included in the third portion.

[0133] In yet another embodiment, the third portion may include a segment-free section in which no segment exists along the winding direction of the electrode assembly.

[0134] Preferably, the third portion may include a plurality of segment-omitted sections along one direction parallel to the winding direction.

[0135] In one embodiment, the width of each of the plurality of segment-omitted sections may increase or decrease along a direction parallel to the winding direction.

[0136] Preferably, the height of the uncoated portion of the segment-omitted section may be substantially the same as the height of the uncoated portion of the first portion or the uncoated portion of the second portion.

[0137] Preferably, the plurality of segments may be arranged radially with respect to a core center of the electrode assembly, and the segment-free section may also be arranged radially with respect to the center of the electrode assembly.

[0138] Preferably, the plurality of segments may be positioned within a predetermined circumferential angle range based on the core center of the electrode assembly.

[0139] In one embodiment, the plurality of segments may be located in two or more sector-shaped or polygonal regions arranged in a circumferential direction with respect to the core center of the electrode assembly.

[0140] Preferably, the angle of the circumference of the sector-shaped region may be 20° or more.

[0141] In yet another embodiment, the second electrode includes a second active material portion coated with an active material layer along the winding direction and a second uncoated portion not coated with an active material layer, at least a portion of the second uncoated portion itself being defined as an electrode tab, the second uncoated portion including a section divided into a plurality of segments that can be bent independently, and the plurality of segments may be bent along the radial direction of the electrode assembly to form a bent surface region.

[0142] To achieve the above object, according to another aspect of the present invention, an electrode assembly is provided in which a core and an outer circumferential surface are defined by winding a first electrode, a second electrode, and a separator interposed therebetween around a winding shaft, wherein the first electrode includes a first active material portion coated with an active material layer along the winding direction and a first uncoated portion not coated with an active material layer, the first uncoated portion includes a section divided into a plurality of segments that can be independently bent from the core side toward the outer circumferential side of the electrode assembly, the plurality of segments are bent along the radial direction of the electrode assembly to form a folded surface region, and the folded surface region includes a uniform stack number section in which the number of layers of the segments is 10 or more along the radial direction, and a decreasing stack number section located adjacent to the uniform stack number section, in which the number of layers of the segments decreases as the distance from the uniform stack number section increases.

[0143] To achieve the above object, according to yet another aspect of the present invention, there is provided an electrode assembly in which a positive electrode, a negative electrode, and a separator interposed therebetween are wound around a winding shaft to define a core and an outer circumferential surface, wherein the positive electrode includes a first active material portion coated with an active material layer along the winding direction and a first uncoated portion not coated with the active material layer, at least a portion of the first uncoated portion is used as an electrode tab, the first uncoated portion includes a plurality of segments that can be independently bent from the core side toward the outer circumferential side of the electrode assembly, the plurality of segments are stacked in multiple layers while being folded along the radial direction of the electrode assembly to form a folded surface region, the folded surface region includes a uniform stack number section in which the number of stacks of the segments is uniform along the radial direction, and a decreasing stack number section located adjacent to the uniform stack number section and in which the number of stacks of the segments decreases as it moves away from the uniform stack number section, and the stack thickness of the segments in the uniform stack number section may be 100 μm to 875 μm.

[0144] Preferably, the electrode assembly may further include a current collector welded to the uniform lamination number section such that at least a portion of the uniform lamination number section and the welding region overlap, and the lamination thickness of the divided piece in the welding region may be 100 μm to 875 μm.

[0145] To achieve the above object, according to yet another aspect of the present invention, there is provided an electrode assembly in which a positive electrode, a negative electrode, and a separator interposed therebetween are wound around a winding shaft to define a core and an outer circumferential surface, wherein the negative electrode includes a first active material portion coated with an active material layer along the winding direction and a first uncoated portion not coated with the active material layer, at least a portion of the first uncoated portion is used as an electrode tab, the first uncoated portion includes a plurality of segments that can be independently bent from the core side toward the outer circumferential side of the electrode assembly, the plurality of segments are multiply stacked while being folded along the radial direction of the electrode assembly to form a folded surface region, the folded surface region includes a uniform stack number section in which the number of stacks of the segments is uniform along the radial direction, and a decreasing stack number section located adjacent to the uniform stack number section and in which the number of stacks of the segments decreases with increasing distance from the uniform stack number section, and the stack thickness of the segments in the uniform stack number section may be 50 μm to 700 μm.

[0146] Preferably, the electrode assembly may further include a current collector welded to the uniform lamination number section such that at least a portion of the uniform lamination number section and the welding region overlap, and the lamination thickness of the divided pieces in the welding region may be 50 μm to 700 μm.

[0147] To achieve the above object, a battery according to one aspect of the present invention is an electrode assembly in which a core and an outer circumferential surface are defined by winding a first electrode, a second electrode, and a separator interposed therebetween around a winding shaft, the first electrode including a first active material portion coated with an active material layer along the winding direction and a first uncoated portion not coated with the active material layer, at least a portion of the first uncoated portion itself being defined as an electrode tab, and the first uncoated portion including a first portion adjacent to the core of the electrode assembly, a second portion adjacent to the outer circumferential surface of the electrode assembly, and a third portion adjacent to the outer circumferential surface of the electrode assembly. and a third portion between the first portion and the second portion, wherein the first portion or the second portion has a height lower than the third portion in the winding axis direction; a battery housing including an open end and a bottom portion facing the open end, which houses the electrode assembly in the space between the open end and the bottom, and which is electrically connected to one of the first electrode and the second electrode and has a first polarity; a sealing body which seals the open end of the battery housing; and a terminal which is electrically connected to the other of the first electrode and the second electrode and has a surface exposed to the outside and has a second polarity.

[0148] In one embodiment, the second portion has a lower height in the winding axis direction than the third portion, the battery housing has a beading portion pressed inward in an area adjacent to the open end, and an inner circumferential surface of the beading portion facing the upper end of the electrode assembly and the second portion may be spaced apart by a predetermined distance.

[0149] Preferably, the pressing depth D1 of the beading portion and the distance D2 from the inner circumferential surface of the battery housing to the boundary point between the second portion and the third portion satisfy the relation D1≦D2.

[0150] In another embodiment, the battery may further include a current collector electrically connected to the third portion, and an insulator covering the current collector and having a periphery interposed and fixed between the inner circumferential surface of the beading portion and the current collector.

[0151] Preferably, the diameter of the current collector is smaller than the minimum inner diameter of the inner circumferential surface of the beading portion, and the diameter of the current collector may be equal to or larger than the outermost diameter of the third portion.

[0152] In another embodiment, the current collector may be positioned higher than the beading portion in the winding axis direction.

[0153] In yet another embodiment, the sealing body may include a cap that seals the open end of the battery housing, a gasket interposed between the periphery of the cap and the open end of the battery housing, and a crimping portion that extends toward the inside of the battery housing, is bent, and wraps around and fixes the periphery of the cap together with the gasket, and the terminal having the second polarity may be the cap.

[0154] In yet another embodiment, the battery further includes a first current collector electrically connected to the first uncoated portion, and the terminal may be a rivet terminal insulatively attached to a through-hole formed in a bottom of the battery housing, electrically connected to the first current collector, and having the second polarity.

[0155] In yet another embodiment, the battery may further include an insulator interposed between an inner surface of the bottom of the battery housing and an upper surface of the first current collector to electrically insulate the inner surface of the bottom of the battery housing from the first current collector.

[0156] Preferably, the insulator has a thickness corresponding to the distance between the inner surface of the bottom of the battery housing and the upper surface of the first current collector, and can be in close contact with the inner surface of the bottom of the battery housing and the upper surface of the first current collector.

[0157] In yet another embodiment, the terminal may include a flat portion at a lower end, the insulator may include an opening exposing the flat portion, and the flat portion may be welded to the first current collector through the opening.

[0158] In yet another embodiment, the second electrode includes a second active material portion coated with an active material layer along the winding direction and a second uncoated portion not coated with an active material layer, the second electrode having the first polarity, and at least a portion of the second uncoated portion itself being defined as an electrode tab. Also, the battery may further include a second current collector electrically connected to the second uncoated portion and having at least a portion of its periphery attached to a sidewall of the battery housing.

[0159] In yet another embodiment, the second electrode includes a second active material portion coated with an active material layer along the winding direction and a second uncoated portion not coated with an active material layer, the second electrode having the first polarity, and at least a portion of the second uncoated portion itself being defined as an electrode tab. The battery may further include a second current collector electrically connected to the second uncoated portion and having at least a portion of its periphery attached to a sidewall of the battery housing. Preferably, the first current collector has an outer diameter equal to or larger than that of the second current collector.

[0160] Preferably, the first current collector and the second current collector are welded to the first uncoated portion and the second uncoated portion along a radial direction of the electrode assembly, respectively, to form a weld pattern, and the length of the weld pattern of the first current collector may be longer than the length of the weld pattern of the second current collector.

[0161] Preferably, the welding pattern of the first current collector and the welding pattern of the second current collector may be positioned at substantially the same distance from the core center of the electrode assembly.

[0162] Preferably, the battery housing includes a beading portion pressed inwardly into an inner wall adjacent to the open end, and the periphery of the second current collector may be electrically connected to the beading portion.

[0163] Preferably, a region of the second current collector that is in electrical contact with the second uncoated portion may be located inside an inner circumferential surface of the beading portion.

[0164] In yet another aspect, the battery may include a non-polarized cap whose periphery is supported by the beading portion, a gasket interposed between the periphery of the cap and an open end of the battery housing, and a crimping portion that extends inside the open end of the battery housing and is bent to wrap around and secure the periphery of the cap together with the gasket. Preferably, the periphery of the second current collector may be interposed and secured between the beading portion and the gasket by the crimping portion.

[0165] Preferably, the periphery of the second current collector may be welded to the beading portion.

[0166] To achieve the above object, a battery according to another aspect of the present invention is an electrode assembly in which a core and an outer circumferential surface are defined by winding a first electrode, a second electrode, and a separator interposed therebetween around a winding shaft, the first electrode including a first active material portion coated with an active material layer along the winding direction and a first uncoated portion not coated with the active material layer, the first uncoated portion including a section divided into a plurality of segments that can be independently bent from a core side toward an outer circumferential side of the electrode assembly, the plurality of segments being bent along a radial direction of the electrode assembly to form a bent surface region, and the bent surface region the battery housing includes: an electrode assembly including a uniform stacking number section in which the number of stacked segments of the segment pieces is 10 or more along the radial direction; and a decreasing stacking number section located adjacent to the uniform stacking number section and in which the number of stacked segments of the segment pieces decreases with increasing distance from the uniform stacking number section; a battery housing including an open end and a bottom facing the open end, which houses the electrode assembly in a space between the open end and the bottom, and which is electrically connected to one of the first electrode and the second electrode and has a first polarity; a sealing body which seals the open end of the battery housing; and a terminal which is electrically connected to the other of the first electrode and the second electrode and has a surface exposed to the outside and has a second polarity.

[0167] To achieve the above object, a battery according to another aspect of the present invention provides an electrode assembly in which a positive electrode, a negative electrode, and a separator interposed therebetween are wound around a winding shaft to define a core and an outer circumferential surface, the positive electrode including a first active material portion coated with an active material layer along the winding direction and a first uncoated portion not coated with the active material layer, at least a portion of the first uncoated portion itself being used as an electrode tab, the first uncoated portion including a plurality of segments that can be independently bent from a core side toward an outer circumferential side of the electrode assembly, the plurality of segments being stacked in multiple layers while being bent along a radial direction of the electrode assembly to form a folded surface region, and the folded surface The surface region includes a uniform stack number section in the radial direction, where the number of stacks of the divided segments is uniform, and a decreasing stack number section located adjacent to the uniform stack number section, where the number of stacks of the divided segments decreases as the distance from the uniform stack number section increases, and the stack thickness of the divided segments in the uniform stack number section is 100 μm to 875 μm; an electrode assembly including an open end and a bottom opposite thereto, which houses the electrode assembly in the space between the open end and the bottom, and is electrically connected to one of the positive electrode and the negative electrode and has a first polarity; a sealing body which seals the open end of the battery housing; and a terminal which is electrically connected to the other of the positive electrode and the negative electrode and has a surface exposed to the outside and has a second polarity.

[0168] Preferably, the battery according to the present invention may further include a current collector welded to the uniform lamination number section so that the uniform lamination number section and the welding area overlap, and the lamination thickness of the divided piece in the welding area may be 100 μm to 875 μm.

[0169] To achieve the above object, a battery according to another aspect of the present invention provides an electrode assembly in which a positive electrode, a negative electrode, and a separator interposed therebetween are wound around a winding shaft to define a core and an outer circumferential surface, the negative electrode including a first active material portion coated with an active material layer along the winding direction and a first uncoated portion not coated with the active material layer, at least a portion of the first uncoated portion itself being used as an electrode tab, the first uncoated portion including a plurality of segments that can be independently bent from a core side toward an outer circumferential side of the electrode assembly, the plurality of segments being stacked in multiple layers while being bent along a radial direction of the electrode assembly to form a bent surface region, and the bent portion The surface region may include a uniform lamination number section in the radial direction, where the number of laminations of the divided segments is uniform, and a decreasing lamination number section located adjacent to the uniform lamination number section, where the number of laminations of the divided segments decreases with increasing distance from the uniform lamination number section, and the lamination thickness of the divided segments in the uniform lamination number section is 50 μm to 700 μm; an electrode assembly including an open end and a bottom facing the open end, which houses the electrode assembly in a space between the open end and the bottom, and which is electrically connected to one of the positive electrode and the negative electrode and has a first polarity; a sealing body which seals the open end of the battery housing; and a terminal which is electrically connected to the other of the positive electrode and the negative electrode and has a surface exposed to the outside and has a second polarity.

[0170] Preferably, the battery according to the present invention may further include a current collector welded to the uniform lamination number section so that the uniform lamination number section and the welding area overlap, and the lamination thickness of the divided piece in the welding area may be 50 μm to 700 μm.

[0171] The above object is achieved by a battery pack including a plurality of the above-described batteries.

[0172] Preferably, the battery may have a height to diameter ratio of greater than 0.4.

[0173] Preferably, the battery form factor may be 46110, 4875, 48110, 4880 or 4680.

[0174] Preferably, the resistance of the battery may be 4 mΩ or less.

[0175] According to one embodiment, in the battery pack, the plurality of batteries may be arranged in a predetermined number of rows, and the electrode terminals of each battery and the outer surface of the bottom of the battery housing may be arranged facing upward.

[0176] According to another aspect, the battery pack may include a plurality of bus bars connecting a plurality of batteries in series and parallel.

[0177] Preferably, the plurality of bus bars are disposed on top of the plurality of batteries, and each of the plurality of bus bars may include a body portion extending between electrode terminals of adjacent batteries, a plurality of first bus bar terminals extending to one side of the body portion and electrically coupled to the electrode terminals of the batteries located on that side, and a plurality of second bus bar terminals extending to the other side of the body portion and electrically coupled to an outer surface of a bottom of a battery housing of the batteries located on the other side.

[0178] The above objectives are achieved by a vehicle including the battery pack described above. [Effects of the Invention]

[0179] According to one aspect of the present invention, the uncoated portions protruding from the upper and lower portions of the electrode assembly are used as electrode tabs, thereby reducing the internal resistance of the battery and increasing the energy density.

[0180] According to another aspect of the present invention, the structure of the uncoated portion of the electrode assembly is improved to prevent interference between the electrode assembly and the inner surface of the battery housing during the process of forming the beading portion of the battery housing, thereby preventing internal short circuits in a cylindrical battery due to partial deformation of the electrode assembly.

[0181] According to yet another aspect of the present invention, the structure of the uncoated portion of the electrode assembly is improved to prevent the uncoated portion from being torn when bent, and the number of overlapping layers of the uncoated portion is sufficiently increased to improve the welding strength of the current collector.

[0182] According to yet another aspect of the present invention, by applying a segment structure to the uncoated portion of the electrode and optimizing the dimensions (width, height, and spacing pitch) of the segments, the number of segments stacked in the area used as the welding target area can be sufficiently increased, thereby improving the physical properties of the area where the current collector is welded.

[0183] According to yet another aspect of the present invention, an electrode assembly having improved energy density and reduced resistance can be provided by applying a structure in which a current collector is welded over a wide area to a folded surface region formed by folding a segment.

[0184] According to yet another aspect of the present invention, a cylindrical battery having an improved design for electrical wiring at the top can be provided.

[0185] According to yet another aspect of the present invention, the structure of the uncoated portion adjacent to the core of the electrode assembly is improved to prevent the cavity in the core of the electrode assembly from being blocked when the uncoated portion is bent, thereby facilitating the electrolyte injection process and the welding process between the battery housing (or terminal) and the current collector.

[0186] According to yet another aspect of the present invention, there can be provided a cylindrical battery having a structure in which internal resistance is low, internal short circuits are prevented, and welding strength between a current collector and a non-coating portion is improved, as well as a battery pack and a vehicle including the same.

[0187] In particular, the present invention can provide a cylindrical battery having a height-to-diameter ratio of 0.4 or more and a resistance of 4 mΩ or less, a battery pack including the same, and a vehicle.

[0188] The present invention has various other effects, which will be described later with reference to examples, but explanations of effects that can be easily inferred by those skilled in the art will be omitted.

[0189] The following drawings attached to this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention, serve to further understand the technical concept of the present invention. Therefore, the present invention should not be interpreted as being limited to only the matters described in the drawings. [Brief explanation of the drawings]

[0190] [Figure 1] 1 is a plan view showing the structure of an electrode used in manufacturing a conventional tabless cylindrical battery. [Figure 2] 1 is a diagram showing the electrode winding process of a conventional tabless cylindrical battery. [Figure 3] 1 is a diagram showing a process of welding a current collector to a folded surface area of a non-coating portion in a conventional tabless cylindrical battery. [Figure 4] 1 is a plan view showing the structure of an electrode according to a first embodiment of the present invention. [Figure 5] FIG. 10 is a plan view showing the structure of an electrode according to a second embodiment of the present invention. [Figure 6] FIG. 10 is a plan view showing the structure of an electrode according to a third embodiment of the present invention. [Figure 7a] FIG. 10 is a plan view showing the structure of an electrode according to a fourth embodiment of the present invention. [Figure 7b] 10 is a diagram illustrating the definition of width, height, and spacing pitch of segments according to an embodiment of the present invention. [Figure 7c] 10 is a diagram illustrating the arc formed by the lower end of a segment, which defines the width of the segment, when the electrode is wound according to an embodiment of the present invention, based on the core center of the electrode assembly. [Figure 7d] This is a diagram showing a schematic diagram of the relationship between the heights h1, h2, h3, and h4 of the segments, the core radius rc, and the radii r1, r2, r3, and r4 of the winding turns at which the segments begin to appear according to an embodiment of the present invention. [Figure 7e] 10 is a conceptual diagram for determining the maximum value hmax for the height H of a segment in a segment height variable section. FIG. [Figure 7f] FIG. 10 is a schematic diagram for explaining the formula for determining the lower interior angle θ of a segment. [Figure 7g] FIG. 10 is a plan view showing a modified structure of an electrode according to a fourth embodiment of the present invention. [Figure 7h] 10 is a top view showing independent regions in which multiple segments can be positioned when an electrode according to a modified example of the present invention is wound into an electrode assembly. FIG. [Figure 8a] FIG. 10 is a plan view showing the structure of an electrode according to a fifth embodiment of the present invention. [Figure 8b] 10 is a diagram illustrating definitions of width, height, and spacing pitch of segments according to another embodiment of the present invention. [Figure 8c] FIG. 10 is a plan view showing a modified structure of an electrode according to a fifth embodiment of the present invention. [Figure 9] 10A to 10C are diagrams illustrating various modified examples of segmented structures according to the present invention; [Figure 10a] 10 is a schematic diagram showing a cross section of a bent surface region formed by bending a segment toward the core of the electrode assembly. FIG. [Figure 10b] 1 is a perspective view schematically illustrating an electrode assembly having a bent surface region formed thereon; [Figure 10c] 10 is a graph showing the results of counting the number of stacked pieces along the radial direction in the folded surface region of the positive electrode formed on the upper part of the electrode assemblies according to Examples 1-1 to 1-7 and a comparative example. [Figure 10d] 10 is a graph showing the results of counting the number of stacked pieces measured along the radial direction in the folded surface region of the positive electrode formed on the upper part of the electrode assembly according to Examples 2-1 to 2-5, Examples 3-1 to 3-4, Examples 4-1 to 4-3, Examples 5-1 and 5-2. [Figure 10e] 10 is a graph showing the results of counting the number of stacked pieces measured along the radial direction in the folded surface region of the positive electrode formed on the upper part of the electrode assemblies according to Examples 6-1 to 6-6 and 7-1 to 7-6. [Figure 10f] 1 is a top view of an electrode assembly showing a uniform lamination number section b1 and a reduced lamination number section b2 in a folded surface region of a segment according to an embodiment of the present invention. [Figure 11] FIG. 1 is a cross-sectional view of a jelly-roll type electrode assembly in which the electrodes of the first embodiment are applied to a first electrode (positive electrode) and a second electrode (negative electrode), taken along the Y-axis direction (winding axis direction). [Figure 12] FIG. 10 is a cross-sectional view of a jelly-roll type electrode assembly in which the electrodes of the second embodiment are applied to the first electrode (positive electrode) and the second electrode (negative electrode), taken along the Y-axis direction (winding axis direction). [Figure 13] FIG. 10 is a cross-sectional view taken along the Y-axis direction (winding axis direction) of a jelly-roll type electrode assembly in which any one of the electrodes of the third to fifth embodiments (modifications thereof) is used as the first electrode (positive electrode) and the second electrode (negative electrode). [Figure 14] 10 is a cross-sectional view of an electrode assembly according to yet another embodiment of the present invention, taken along the Y-axis direction (winding axis direction). [Figure 15] 10 is a cross-sectional view of an electrode assembly according to yet another embodiment of the present invention, taken along the Y-axis direction (winding axis direction). [Figure 16] 10 is a cross-sectional view of an electrode assembly according to yet another embodiment of the present invention, taken along the Y-axis direction (winding axis direction). [Figure 17] 1 is a cross-sectional view of a cylindrical battery according to an embodiment of the present invention taken along the Y-axis direction. [Figure 18] 4 is a cross-sectional view of a cylindrical battery according to another embodiment of the present invention taken along the Y-axis direction. FIG. [Figure 19] 10 is a cross-sectional view of a cylindrical battery according to yet another embodiment of the present invention, taken along the Y-axis direction. [Figure 20] 10 is a cross-sectional view of a cylindrical battery according to yet another embodiment of the present invention, taken along the Y-axis direction. [Figure 21] 10 is a cross-sectional view of a cylindrical battery according to yet another embodiment of the present invention, taken along the Y-axis direction. [Figure 22] 10 is a cross-sectional view of a cylindrical battery according to yet another embodiment of the present invention, taken along the Y-axis direction. [Figure 23] 10 is a cross-sectional view of a cylindrical battery according to yet another embodiment of the present invention, taken along the Y-axis direction. [Figure 24] 10 is a cross-sectional view of a cylindrical battery according to yet another embodiment of the present invention, taken along the Y-axis direction. [Figure 25] 10 is a cross-sectional view of a cylindrical battery according to yet another embodiment of the present invention, taken along the Y-axis direction. [Figure 26] FIG. 2 is a top view showing the structure of a first current collector according to an embodiment of the present invention. [Figure 27] FIG. 3 is a top view showing the structure of a second current collector according to an embodiment of the present invention. [Figure 28] FIG. 10 is a top view showing a state in which a plurality of cylindrical batteries are electrically connected. [Figure 29] FIG. 29 is a partially enlarged view of FIG. 28. [Figure 30] 1 is a diagram illustrating a schematic configuration of a battery pack according to an embodiment of the present invention; [Figure 31] 1 is a schematic diagram of a vehicle including a battery pack according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0191] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, the terms and words used in the specification and claims should not be interpreted as being limited to their ordinary and dictionary meanings, but should be interpreted as having meanings and concepts corresponding to the technical ideas of the present invention, in accordance with the principle that the inventor himself can appropriately define the concepts of terms in order to best explain the invention.

[0192] Therefore, it should be understood that the embodiments described in this specification and the configurations shown in the drawings are merely the most preferred embodiment of the present invention and do not represent the entire technical idea of the present invention, and that there may be various equivalents and modifications that can be substituted for them at the time of this application.

[0193] In order to facilitate understanding of the invention, the accompanying drawings may not be drawn to scale, and the dimensions of some components may be exaggerated. In addition, the same reference numerals may be used to refer to the same components in different embodiments.

[0194] The expression that two comparison objects are identical means that they are "substantially identical." Therefore, "substantially identical" may include deviations that are considered low in the art, for example, deviations within 5%. Furthermore, the expression that a parameter is uniform in a given region means that the parameter is uniform on average in that region.

[0195] Furthermore, although terms such as "first" and "second" are used to indicate various components, these terms are not intended to limit the components. These terms are used merely to distinguish one component from another, and unless otherwise specified, the first component can also be the second component.

[0196] Throughout the specification, unless otherwise stated, each element may be singular or plural.

[0197] When an arbitrary structure is placed "on (or under)" a component or "above (or below)" a component, it means not only that the arbitrary structure is placed in contact with the upper surface (or lower surface) of the component, but also that other structures may be interposed between the component and the arbitrary structure placed above (or below) the component.

[0198] Furthermore, when a component is said to be "coupled," "coupled," or "connected" to another component, it does not only mean that the components are directly coupled or connected to each other, but also that other components are "intervening" between the components, or that each component is "coupled," "coupled," or "connected" through other components.

[0199] Throughout the specification, unless otherwise specified, "A and / or B" means A, B, or A and B, and "C to D" means C or more and D or less, unless otherwise specified.

[0200] For ease of explanation, in this specification, the direction along the longitudinal direction of the winding shaft of the electrode assembly wound into a jelly roll is referred to as the axial direction (Y-axis direction). The direction surrounding the winding shaft is referred to as the circumferential direction or outer circumferential direction (X-axis direction). The direction approaching or moving away from the winding shaft is referred to as the radial direction. Of these, the direction approaching the winding shaft is referred to as the centripetal direction, and the direction moving away from the winding shaft is referred to as the centrifugal direction.

[0201] First, an electrode assembly according to an embodiment of the present invention will be described. The electrode assembly may be a jelly-roll type electrode assembly having a structure in which sheet-like first and second electrodes are wound in one direction with a separator interposed therebetween. However, the present invention is not limited by the type of electrode assembly.

[0202] Preferably, at least one of the first and second electrodes includes an uncoated portion on a long side edge in the winding direction where no active material is coated. At least a portion of the uncoated portion itself serves as an electrode tab. The uncoated portions include a core-side uncoated portion adjacent to the core of the electrode assembly, an outer-side uncoated portion adjacent to the outer peripheral surface of the electrode assembly, and an intermediate uncoated portion interposed between the core-side uncoated portion and the outer-side uncoated portion.

[0203] Preferably, at least one of the core-side uncoated portion and the outer-periphery-side uncoated portion has a height relatively lower than that of the intermediate uncoated portion.

[0204] FIG. 4 is a plan view showing the structure of an electrode 40 according to a first embodiment of the present invention.

[0205] Referring to FIG. 4, the electrode 40 of the first embodiment includes a current collector 41 made of metal foil and an active material layer 42. The metal foil may be made of a conductive metal, such as aluminum or copper, and is appropriately selected depending on the polarity of the electrode 40. An active material layer 42 is formed on at least one surface of the current collector 41. The active material layer 42 is formed along the winding direction X. The electrode 40 includes an uncoated portion 43 at the end of a long side in the winding direction X. The uncoated portion 43 is a portion of the current collector 41 that is not coated with an active material. The region of the current collector 41 on which the active material layer 42 is formed is referred to as the active material portion.

[0206] In electrode 40, the width of the active material portion in the direction of the short sides of current collector 41 may be 50 mm to 120 mm, and the length of the active material portion in the direction of the long sides of current collector 41 may be 3 m to 5 m. Therefore, the ratio of the short sides to the long sides of the active material portion may be 1.0% to 4.0%.

[0207] Desirably, in electrode 40, the width of the active material portion in the direction of the short sides of current collector 41 may be 60 mm to 70 mm, and the length of the active material portion in the direction of the long sides of current collector 41 may be 3 m to 5 m. Therefore, the ratio of the short sides to the long sides of the active material portion may be 1.2% to 2.3%.

[0208] The ratio of the short side to the long side of the active material portion is significantly smaller than the 6% to 11% level of the ratio of the long side to the short side of the active material portion of an electrode used in a cylindrical battery having an 1865 or 2170 form factor.

[0209] Preferably, the current collector 41 has an elongation ratio of 1.5% to 3.0% and a tensile strength of 25 gf / mm 2 ~35kgf / mm 2The elongation rate and tensile strength can be measured according to the measurement method of IPC-TM-650. The electrode 40 is manufactured by forming an active material layer 42 on a current collector 41 and then compressing the formed electrode. During the compression process, the uncoated region 43 and the active material layer 42 have different elongation rates. Therefore, the electrode 40 after compression swells, and the longer the electrode 40, the more severe the swell becomes.

[0210] Optimizing the elongation rate and tensile strength of the current collector 41 reduces the camber length after crimping to less than 20 mm when the electrode 40 is 4 m long. The camber length is the maximum amount of deflection of the electrode 40 in the winding direction X when the electrode 40 is unfolded with undulations. The maximum amount of deflection can be measured at the outer end. Because the camber length of an electrode 40 with an optimized elongation rate and tensile strength of the current collector 41 is short, meandering defects do not occur during the notching of the plain portion 43 or the winding process of the electrode 40.

[0211] The smaller the elongation ratio of the current collector 41, the more easily it breaks. If the elongation ratio of the current collector 41 is less than 1.5%, the rolling processability of the current collector 41 decreases, and when an electrode 40 coated with an active material layer 42 is crimped to the current collector 41, the current collector 41 may break. On the other hand, if the elongation ratio of the current collector 41 exceeds 3.0%, the active material portion of the electrode 40 is excessively elongated, and the camber length increases significantly. If the tensile strength of the current collector 41 is 25 kgf / mm 2 Less than or equal to 35kgf / mm 2 If the temperature exceeds this range, the electrode processability of the electrode 40 will be reduced.

[0212] The camber phenomenon is particularly problematic in positive electrode current collectors made of aluminum foil. 2 ~35kgf / mm 2 By using the aluminum foil as a current collector, the camber phenomenon can be suppressed. It is desirable to form an active material layer on such a current collector and use it as a positive electrode.

[0213] Preferably, an insulating coating layer 44 may be formed at the boundary between the active material layer 42 and the uncoated portion 43. The insulating coating layer 44 is formed so that at least a portion thereof overlaps the boundary between the active material layer 42 and the uncoated portion 43. The insulating coating layer 44 prevents short-circuiting between two electrodes of opposite polarity that face each other via a separator. The insulating coating layer 44 may cover the boundary between the active material layer 42 and the uncoated portion 43 with a width of 0.3 mm to 5 mm. The width of the insulating coating layer 44 may vary along the winding direction of the electrode 40. The insulating coating layer 44 includes a polymer resin and may also include an inorganic filler such as Al2O3. The portion of the current collector 41 covered by the insulating coating layer 44 may be considered an uncoated portion because it is not a region coated with an active material layer.

[0214] The uncoated portion 43 includes a core-side uncoated portion B1 adjacent to the core side of the electrode assembly, an outer-periphery-side uncoated portion B3 adjacent to the outer periphery side of the electrode assembly, and an intermediate uncoated portion B2 interposed between the core-side uncoated portion B1 and the outer-periphery-side uncoated portion B3.

[0215] When the electrode 40 is wound into a jelly roll-type electrode assembly, the core-side uncoated area B1, the outer-periphery-side uncoated area B3, and the middle uncoated area B2 can be defined as the uncoated area adjacent to the core side, the uncoated area adjacent to the outer periphery, and the uncoated area excluding these, respectively.

[0216] Hereinafter, the core-side uncoated portion B1, the outer-periphery-side uncoated portion B3, and the middle uncoated portion B2 will be referred to as the first portion, the second portion, and the third portion, respectively.

[0217] For example, the first portion B1 may be an uncoated portion of the electrode area including the innermost winding turn, and the second portion B1 may be an uncoated portion of the electrode area including the outermost winding turn. The winding turns may be counted relative to the core end of the electrode assembly.

[0218] As another example, the boundary between B1 and B2 may be appropriately defined at a point where the height (or change pattern) of the uncoated portion substantially changes from the core side to the outer periphery side of the electrode assembly, or at a point that is a predetermined percentage based on the radius of the electrode assembly (e.g., 5%, 10%, 15% of the radius, etc.).

[0219] The B2 / B3 boundary may be defined as a point where the height (or variation pattern) of the uncoated portion substantially changes from the outer periphery side to the core side of the electrode assembly, or as a predetermined percentage point based on the radius of the electrode assembly (e.g., 85%, 90%, 95% of the radius, etc.). Once the B1 / B2 boundary and the B2 / B3 boundary are identified, the third portion B2 may be automatically identified.

[0220] If only the B1 / B2 boundary is specified, the B2 / B3 boundary can be appropriately selected at a point near the outer periphery of the electrode assembly. For example, the second portion can be defined as the uncoated portion of the electrode region that constitutes the outermost winding turn. On the other hand, if only the B2 / B3 boundary is specified, the B1 / B2 boundary can be appropriately selected at a point near the core side of the electrode assembly. For example, the first portion can be defined as the uncoated portion of the electrode region that constitutes the innermost winding turn.

[0221] It is not excluded that another structure is interposed between the first portion B1 and the third portion B2, and it is also not excluded that another structure is interposed between the third portion B2 and the second portion B3.

[0222] In the first embodiment, the height of the non-coating portion 43 is not constant but varies relatively in the winding direction X. That is, the height (length in the Y-axis direction) of the second portion B3 is greater than or equal to 0 and is relatively shorter than the first portion B1 and the third portion B2. Here, the height of each portion may be an average height or a maximum height, and the same applies below. In the winding direction, the length of the third portion B2 is longer than the first portion B1 and the second portion B3.

[0223] FIG. 5 is a plan view showing the structure of an electrode 45 according to a second embodiment of the present invention.

[0224] Referring to FIG. 5, the electrode 45 of the second embodiment differs from the first embodiment only in that the height of the second portion B3 gradually decreases toward the outer periphery, and the other configurations are substantially the same.

[0225] In one variant, the second portion B3 can be deformed into a step shape (see dotted lines) with a stepwise decreasing height.

[0226] FIG. 6 is a plan view showing the structure of an electrode 50 according to a third embodiment of the present invention.

[0227] 6, in the third embodiment of the electrode 50, the heights of the first portion B1 and the second portion B3 are equal to or greater than 0 and are relatively lower than the third portion B2. The heights of the first portion B1 and the second portion B3 may be the same or different.

[0228] Preferably, the height of the third portion B2 may have a step shape that increases stepwise from the core side toward the outer periphery side.

[0229] Patterns 1 to 7 divide the third portion B2 around the positions where the height of the uncoated portion 43 changes. Preferably, the number of patterns, the height (length in the Y-axis direction) and the width (length in the X-axis direction) of each pattern can be adjusted to maximize stress distribution during the bending process of the uncoated portion 43. The stress distribution is intended to prevent the uncoated portion 43 from breaking when it is bent toward the core of the electrode assembly.

[0230] Width d of the first portion B1 B1 The third portion B2 is designed so that the core of the electrode assembly is not blocked when the pattern of the third portion B2 is bent toward the core. The core refers to the cavity present at the center of the winding of the electrode assembly.

[0231] For example, the width dB1 of the first portion B1 may increase in proportion to the bending length of the pattern 1. The bending length corresponds to the height of the pattern based on the bending point of the pattern.

[0232] Preferably, the width d of the first portion B1 B1 The width d of the first portion B1 may be set so that the radial width of the wound turn formed by the first portion B1 is equal to or greater than the bending length of the pattern 1. B1 may be set so that the value obtained by subtracting the radial width of the winding turn formed by the first portion B1 from the bent length of pattern 1 is less than 0 or 10% or less of the core radius.

[0233] In a specific example, when the electrode 50 is used to manufacture an electrode assembly for a cylindrical battery with a form factor of 4680, the width d of the first portion B1 is B1 can be set to 180 mm to 350 mm depending on the diameter of the core of the electrode assembly and the bending length of the pattern 1.

[0234] In one example, the width of each pattern can be designed to comprise one or more winding turns of the electrode assembly.

[0235] In one variation, the height of the third portion B2 may have a step shape that increases and then decreases from the core side toward the outer periphery side.

[0236] In another variation, the second portion B3 can be modified to have the same structure as in the second embodiment.

[0237] In yet another variant, the pattern structure applied to the third portion B2 can be extended to the second portion B3 (see dotted line).

[0238] FIG. 7a is a plan view showing the structure of an electrode 60 according to a fourth embodiment of the present invention.

[0239] 7a, in the fourth embodiment of the electrode 60, the heights of the first and second portions B1 and B3 in the direction of the winding axis (Y) are equal to or greater than 0 and are relatively lower than the third portion B2. The heights of the first and second portions B1 and B3 in the direction of the winding axis (Y) may be the same or different.

[0240] Preferably, at least a portion of the third portion B2 may include a plurality of segment segments 61. The height of the plurality of segment segments 61 may increase stepwise from the core side toward the outer periphery. The plurality of segment segments 61 may have a geometric shape in which the width decreases from the bottom toward the top. Preferably, the geometric shape is a trapezoid. As will be described later, the shape of the geometric shape may be modified in various ways.

[0241] The section 61 may be laser notched. The section 61 may be formed by known metal foil cutting processes such as ultrasonic cutting or punching.

[0242] In the fourth embodiment, a predetermined gap is preferably provided between the lower end of the cut groove (G in FIG. 7b) between the adjacent cut pieces 61 and the active material layer 42 to prevent damage to the active material layer 42 and / or the insulating coating layer 44 during the bending process of the uncoated portion 43. This is because stress is concentrated near the lower end of the cut groove 63 when the uncoated portion 43 is bent. The gap may vary along the winding direction of the electrode 60. The gap is preferably 0.2 mm to 4 mm, and more preferably 1.5 mm to 2.5 mm. Adjusting the gap within the above numerical range prevents damage to the active material layer 42 and / or the insulating coating layer 44 near the lower end of the cut groove 63 due to stress generated during the bending process of the uncoated portion 43. Furthermore, the gap prevents damage to the active material layer 42 and / or the insulating coating layer 44 due to tolerances during notching or cutting the cut pieces 61. In one direction parallel to the winding direction, the gap may be substantially constant or may vary. In the latter case, the gap between the plurality of segments may vary individually, in groups, or in groups of two or more groups in a direction parallel to the winding direction. The lower ends of the cutting grooves 63 and the insulating coating layer 44 may be spaced apart by 0.5 mm to 2.0 mm. The distance between the lower ends of the cutting grooves 63 and the insulating coating layer 44 in a direction parallel to the winding direction may be substantially uniform or may vary. In the latter case, the gap between the plurality of segments may vary individually, in groups, or in groups of two or more groups in a direction parallel to the winding direction. When the electrode 60 is wound, the end of the insulating coating layer 44 in the winding axis (Y) direction may be located within a range of -2 mm to 2 mm along the winding axis direction from the end of the separator. The insulating coating layer 44 prevents short-circuiting between two electrodes of opposite polarity facing each other across the separator and supports the bending point when the segment 61 is bent. To improve the effect of preventing short circuits between the two electrodes, the insulating coating layer 44 may be exposed to the outside of the separator. Also, to further maximize the effect of preventing short circuits between the two electrodes, the width of the insulating coating layer 44 may be increased so that the end of the insulating coating layer 44 in the winding axis (Y) direction is positioned above the lower end of the cutting groove 63.In one example, the end of the insulating coating layer 44 in the winding axis direction may be located within a range of −2 mm to +2 mm from the lower end of the cutting groove 63. The thickness of the insulating coating layer 44 may be thinner than that of the active material layer. In this case, a gap may exist between the surface of the insulating coating layer 44 and the separator.

[0243] In one embodiment, the plurality of segment pieces 61 may be arranged in a plurality of segment groups from the core side toward the outer periphery side. At least one of the width, height, and spacing pitch of the segment pieces belonging to the same segment group may be substantially the same. Preferably, the width, height, and spacing pitch of the segment pieces belonging to the same segment group may be the same.

[0244] Preferably, the width and height of the segments belonging to the same segment group may be substantially the same.

[0245] In another embodiment, the plurality of segments may be spaced apart in groups or in groups of two or more, with the spacing pitch gradually or stepwise increasing from the core side to the outer periphery side, or vice versa.

[0246] In yet another embodiment, the spacing pitch of the multiple segments may gradually or stepwise increase and then gradually or stepwise decrease from the core side to the outer periphery side, in groups or in groups of two or more, or vice versa.

[0247] In yet another embodiment, the gap between the lower end of the cutting groove 63 and the insulating coating layer 44 or the active material layer 42 of the multiple cut pieces may increase gradually or stepwise from the core side to the outer periphery side, or vice versa.

[0248] In still another embodiment, the gap between the lower end of the cutting groove 63 and the insulating coating layer 44 or the active material layer 42 of the plurality of cut pieces may gradually or stepwise increase or decrease from the core side to the outer periphery side, or vice versa.

[0249] FIG. 7b is a diagram showing the definitions of the width D, height H and spacing pitch P of the trapezoidal segment 61.

[0250] Referring to FIG. 7b, the width D, height H, and spacing pitch P of the divided pieces 61 are designed to prevent abnormal deformation of the plain portion 43 while sufficiently increasing the number of overlapping layers of the plain portion 43 to prevent tearing of the plain portion 43 near the bending point during bending and to ensure sufficient welding strength.

[0251] The bending of the segment 61 is performed along or above a line G passing through the lower end of the cutting groove 63. The cutting groove 63 allows the segment 61 to be smoothly and easily bent in the radial direction of the electrode assembly.

[0252] The width D of the segment 61 is defined as the length between two points where two straight lines extending from both side edges 63b of the segment 61 intersect with a straight line extending from the bottom 63a of the cutting groove 63. The height H of the segment 61 is defined as the shortest distance between the top edge of the segment 61 and a straight line extending from the bottom 63a of the cutting groove 63. The spacing pitch P of the segment 61 is defined as the length between two points where a straight line extending from the bottom 63a of the cutting groove 63 intersects with a straight line extending from the two side edges 63b connected to the bottom 63a. When the side edges 63b and / or the bottom edge 63a are curved, the straight lines may be replaced by tangent lines extending from the side edges 63b and / or the bottom edge 63a at the intersections of the side edges 63b and the bottom edge 63a.

[0253] Preferably, the width D of the divided pieces 61 is 1 mm or more. If D is less than 1 mm, when the divided pieces 61 are bent toward the core, the divided pieces 61 may not overlap to an extent that sufficient welding strength can be ensured, or empty spaces (gaps) may occur.

[0254] Preferably, the width D of the segment 61 can be adaptively adjusted according to the radius of the winding turn in which the segment 61 is located so that the segment 61 can easily overlap radially when the segment 61 is bent toward the core side of the electrode assembly.

[0255] FIG. 7c shows the bottom end of the segment 61 (line segment D in FIG. 7b) that defines the width D of the segment 61 when the electrode 60 is wound according to an embodiment of the present invention. ab ) is a diagram showing the arc A1A2 formed by the core center O of the electrode assembly as a reference.

[0256] 7c, arc A1A2 has a length corresponding to width D of segment 61 and has a circumferential angle Φ relative to the core center of the electrode assembly. Circumferential angle Φ can be defined as the angle between two line segments connecting both ends of arc A1A2 and core center O on a plane perpendicular to the winding axis and passing through arc A1A2.

[0257] When the length of the arc A1A2 of the minute segment 61 is the same, the inclination angle Φ decreases as the radius r of the winding turn on which the minute segment 61 is located increases. Conversely, when the inclination angle Φ of the minute segment 61 is the same, the length of the arc A1A2 increases proportionally as the radius r of the winding turn on which the minute segment 61 is located increases.

[0258] The inclination angle Φ affects the bending quality of the segment 61. In the drawing, the solid arrow indicates the direction of the force applied to bend the segment 61, and the dotted arrow indicates the direction in which the segment 61 is bent. The bending direction is toward the core center O.

[0259] The circumferential angle Φ of the segment 61 may be 45° or less, preferably 30°, depending on the radius r of the winding turn where the segment 61 is located, in order to improve the uniformity of the folding and prevent the occurrence of cracks.

[0260] In one embodiment, the circumferential angle Φ of the segment 61 may increase or decrease gradually or stepwise along the radial direction of the electrode assembly within the above numerical range. In another embodiment, the circumferential angle Φ of the segment 61 may increase gradually or stepwise and then decrease gradually or stepwise along the radial direction of the electrode assembly within the above numerical range, or vice versa. In yet another embodiment, the circumferential angle Φ of the segment 61 may be substantially constant along the radial direction of the electrode assembly within the above numerical range.

[0261] Experiments have shown that if the circumferential angle Φ of the segment 61 exceeds 45°, the folding pattern of the segment 61 will not be uniform. The difference in force applied to the center and side edges of the segment 61 will increase, causing the segment 61 to be pressed unevenly in the circumferential direction. Furthermore, if the pressing force is increased to ensure uniform folding, cracks may occur in the plain portion 43 near the cut grooves 63.

[0262] In one example, the circular angles Φ of the segments 61 included in the electrode 60 may be substantially identical, and the widths of the segments 61 may increase proportionally as the radius r of the winding turn on which the segments 61 are located increases. "Substantially identical" means either completely identical or with a deviation of less than 5%.

[0263] For example, when the radius of the electrode assembly is 22 mm, the radius of the core is 4 mm, and the segment 61 is disposed from a winding turn located at a radius of 7 mm, if the inclination angle Φ of the segment 61 is constant at 28.6°, the width D of the segment 61 may increase proportionally depending on the radius r of the winding turn on which the segment 61 is located, as shown in Table 1 below. That is, the width of the segment 61 may increase by 0.5 mm at substantially the same rate for every 1 mm increase in the radius r of the winding turn. [Table 1]

[0264] Preferably, the width D(r) of the segment 61 located on the winding turn having a radius r based on the core center O of the electrode assembly can be determined within a range that satisfies the following Equation 1. [Formula 1] 1≦D(r)≦(2×π×r / 360°)×45°

[0265] Preferably, each of the plurality of segments 61 may have a width D(r) in the winding direction that gradually or stepwise increases as the radius r of the winding turn in which the segment 61 is located increases relative to the core center of the electrode assembly, or vice versa.

[0266] In another embodiment, each of the plurality of segments 61 may have a width D(r) in the winding direction that gradually or stepwise increases in the range of 1 mm to 11 mm as the radius r of the winding turn in which the segment 61 is located increases relative to the core center of the electrode assembly, or vice versa.

[0267] In yet another embodiment, each of the plurality of segments 61 may have a width D(r) in the winding direction that gradually or stepwise increases and then gradually or stepwise decreases as the radius r of the winding turn in which the segment 61 is located increases relative to the core center of the electrode assembly, or vice versa.

[0268] In yet another embodiment, each of the plurality of segments 61 may have a width D(r) in the winding direction that gradually or stepwise increases and then gradually or stepwise decreases in the range of 1 mm to 11 mm as the radius r of the winding turn in which the segment 61 is located increases relative to the core center of the electrode assembly, or vice versa.

[0269] In still other embodiments, the rate at which the width D(r) of the segment 61 changes as the radius r of the winding turn in which the segment 61 is located increases can be the same or different.

[0270] In yet another embodiment, the rate at which the width D(r) of the segment 61 varies as the radius r of the winding turn on which the segment 61 is located increases may be the same or different, ranging from 1 mm to 11 mm.

[0271] 7b, the height H of the divided pieces 61 may be 2 mm or more. If D2 is less than 2 mm, when the divided pieces 61 are bent toward the core, the divided pieces 61 may not overlap to an extent that sufficient welding strength can be ensured, or empty spaces (gaps) may be generated.

[0272] The height H of the segment 61 can be determined by applying the condition that the segment 61 does not block the core when bent toward the core. Preferably, the height H of the segment 61 can be adjusted so that 90% or more of the diameter of the core is open to the outside.

[0273] Preferably, the height H of the segment 61 may increase from the core side toward the outer periphery depending on the radius of the winding turn in which the segment 61 is located and the radius of the core.

[0274] In one example, the height H of the segment 61 increases from h1 to h2 as the radius of the winding turn increases. N When the k-th height of the segment 61 is increased stepwise over N steps up to h k (k is a natural number between 1 and N), height h k The starting radius of the winding turn containing the segment 61 is r k , the radius of the core is r c Then, the heights h1 to h2 of the segment 61 are determined so that the following formula 2 is satisfied. N can be determined. [Formula 2] 2mm≦h k ≦r k -α×r c (Preferably, α is 0.90 to 1.)

[0275] The height of the segment 61 h k If formula 2 is satisfied, even if the segment piece 61 is bent toward the core, 90% or more of the diameter of the core can be exposed to the outside.

[0276] For example, the electrode 60 may have an overall winding turn radius of 22 mm, with the height of the sub-segment 61 starting at 3 mm, and the height of the sub-segment 61 sequentially increasing to 3 mm, 4 mm, 5 mm, and 6 mm with each 1 mm increase in the radius of the winding turn including the sub-segment 61, while the height of the remaining winding turns may remain substantially constant at 6 mm. That is, the radial width of the height-variable section of the sub-segment 61 within the overall winding turn radius is 3 mm, and the remaining radius sections correspond to uniform height sections.

[0277] In this case, the starting radii r1, r2, r3, and r4 of the winding turn including the segment 61 having heights of 3 mm, 4 mm, 5 mm, and 6 mm according to the radius rc of the core of the electrode assembly are as shown in Table 2 below, when α is 1 and the equality condition is applied in the right-hand inequality. [Table 2]

[0278] When the segment 61 is positioned at the radial position shown in Table 2, the segment 61 will not block the core even if it is bent toward the core. Meanwhile, r1, r2, r3, and r4 shown in Table 2 can be shifted toward the core depending on the α value. In one example, when α is 0.90, r1, r2, r3, and r4 can be shifted toward the core by 10% of the core radius. In this case, when the segment 61 is bent toward the core, 10% of the core radius is blocked by the segment 61. r1, r2, r3, and r4 shown in Table 2 are limit values for the position where the segment 61 starts. Therefore, the position of the segment 61 can be shifted a predetermined distance toward the outer periphery from the radius shown in Table 2. Figure 7d shows the relationship between the heights h1, h2, h3, and h4 of the segment 61 and the core radius r c 10 is a diagram showing a schematic relationship between the radii r1, r2, r3, and r4 of the winding turns at which the winding segment 61 begins to appear.

[0279] Referring to Table 2 and FIG. 7d, for example, the radius r of the core C cWhen the radius of the core C is 3 mm, the starting radii r1, r2, r3, and r4 of the winding turn including the segment 61 with heights of 3 mm (h1), 4 mm (h2), 5 mm (h3), and 6 mm (h4) may be 6 mm, 7 mm, 8 mm, and 9 mm, respectively, and the height of the segment 61 may be maintained at 6 mm from the radius of 9 mm to the last winding turn. Furthermore, the segment 61 may not be included in a winding turn having a radius smaller than 6 mm (r1). In this example, the segment 61 with a height of 3 mm (h1) closest to the core C is located from the winding turn with a radius of 6 mm. Therefore, even if the segment 61 is bent toward the core C, it only covers the radius section from 3 mm to 6 mm, and does not substantially block the core C. The position of the segment 61 is determined by the value of α in Equation 2, depending on the core radius r. c can be shifted to the core C side within 10% of the

[0280] In other embodiments, the height of the segment 61 may increase at the same or different rates as the starting radius r of the winding turn in which the segment 61 is located increases relative to the core center of the electrode assembly.

[0281] Preferably, the height H of the segment 61 satisfies Equation 2, and the maximum height of the segment 61 can be limited.

[0282] FIG. 7e shows the maximum value h of the height H of the segment 61 in the height variable section of the segment 61. max FIG. 1 is a conceptual diagram for determining

[0283] Referring to FIG. 7e, in the wound structure of the electrode assembly, the electrode E1 including the segment 61 faces the electrode E2 of the opposite polarity in the radial direction with the separator S interposed therebetween. 1,active is coated on both sides of the electrode E2, and the active material layer E 2,active For electrical insulation, the edge S of the separation membrane S is coated end is the end E of electrode E2 2,end From the insulation gap W gapThe end of electrode E1 does not extend further outward than the end of electrode E2 for electrical insulation. Therefore, an insulating gap W is formed at the lower end of the uncoated portion 43. gap In addition, when the electrodes E1 and E2 and the separator S are wound up, the end S of the separator S must be secured. end Therefore, in order for the segment 61 to be exposed to the outside of the separation membrane S, the section W corresponding to the minimum meandering margin of the separation membrane S must be margin,min must be allocated to the plain portion 43. In addition, in order to cut the cut pieces 61, a minimum cutting scrap margin W must be provided at the end of the current collector foil. scrap,min Therefore, the maximum height h of the segment 61 must be max can be determined by the following equation 3: foil corresponds to the width of the current collector foil before it is cut. [Formula 3] h max =W foil -W scrap,min -W margin,min -W gap

[0284] Preferably, the insulating gap W gap When the first electrode is a positive electrode, the insulating gap W may be 0.2 mm to 6 mm. gap When the first electrode is a negative electrode, the thickness may be 0.1 mm to 2 mm.

[0285] Preferably, the cutting minimum scrap margin W scrap,min The minimum cutting scrap margin W can be 1.5mm to 8mm. scrap,min may not be assigned depending on the process of forming the divided piece 61. For example, the cutting groove 63 may be formed so that the upper end edge of the divided piece 61 coincides with the upper end edge of the current collector foil. In this case, in Equation 3, W scrap,min can be 0.

[0286] Preferably, the minimum meandering margin W of the separation membrane margin,min can be 0 to 1 mm.

[0287] As an example, the minimum cutting scrap margin W scrap,min is 1.5 mm, and the minimum meandering margin W of the separation membrane S margin,min Under these conditions, the width W of the current collector foil before forming the divided pieces 61 may be 0.5 mm. foil is 8mm~12mm, and the insulation gap W gap When is 0.6 mm, 0.8 mm, and 1.0 mm, the maximum height h of the segment 61 is calculated using Equation 3. max The calculation results are shown in Table 3 below. [Table 3]

[0288] Referring to Table 3, the maximum height h of the segment 61 in the height variable section of the segment 61 is max may be set to 10 mm. Therefore, the height of the segment 61 in the height-variable section of the segment 61 satisfies Equation 2 and may increase stepwise or gradually in the radial direction of the electrode assembly from 2 mm to 10 mm. Referring again to FIG. 7b, the spacing pitch P of the segment 61 may be adjusted in the range of 0.05 to 1 mm. If the spacing pitch P is less than 0.05 mm, stress may cause cracks in the uncoated portion 43 near the bottom of the cut groove 63 when the electrode 60 travels during a winding process, etc. On the other hand, if the spacing pitch P exceeds 1 mm, when the segment 61 is bent, the segment 61 may not overlap to an extent sufficient to ensure sufficient welding strength, or empty spaces (gaps) may be generated.

[0289] On the other hand, when the current collector 41 of the electrode 60 is made of aluminum, it is more desirable to set the separation pitch P to 0.5 mm or more. When the separation pitch P is 0.5 mm or more, even if the electrode 60 travels at a speed of 100 mm / sec or more under a tension of 300 gf or more during a winding process or the like, it is possible to prevent cracks from occurring below the cutting grooves 63.

[0290] According to the experimental results, when the current collector 41 of the electrode 60 is an aluminum foil having a thickness of 15 μm and the separation pitch P is 0.5 mm or more, no cracks occur below the cutting groove 63 when the electrode 60 runs under the running conditions described above.

[0291] As shown in FIG. 7b, a cut groove 63 is interposed between two adjacent segments 61 in the winding direction X. The cut groove 63 corresponds to a space created when the plain portion 43 is removed. Preferably, the corners at both lower ends of the cut groove 63 are rounded. That is, the cut groove 63 includes a substantially flat bottom portion 63a and a rounded portion 63c. The rounded portion 63c connects the bottom portion 63a to a side edge 63b of the segment 61. Alternatively, the bottom portion 63a of the cut groove 63 may be shaped like an arc. In this case, the side edge 63b of the segment 61 can be smoothly connected by the arc-shaped bottom portion 63a.

[0292] The radius of curvature of the rounded portion 63c may be greater than 0 and less than or equal to 0.5 mm, preferably greater than 0 and less than or equal to 0.1 mm, and more preferably 0.01 mm to 0.05 mm. When the radius of curvature of the rounded portion 63c satisfies the above numerical range, it is possible to prevent cracks from occurring below the cutting groove 63 while the electrode 60 is traveling during a winding process or the like.

[0293] The lower interior angle θ of the plurality of segment pieces 61 may increase from the core side toward the outer periphery. As an example, the lower interior angle θ of the plurality of segment pieces 61 may increase gradually or in steps from the core side toward the outer periphery. The lower interior angle θ is the angle between a line extending from the bottom 63a of the cutting groove 63 and a line extending from the side edge 63b of the segment piece 61. When the segment piece 61 is bilaterally symmetrical, the lower interior angle θ on the left and right sides is substantially the same.

[0294] As the radius of the electrode assembly increases, the radius of curvature also increases. If the lower interior angle θ of the segment 61 increases with the radius of the electrode assembly, stresses occurring in the radial and circumferential directions when the segment 61 is bent can be alleviated. Furthermore, as the lower interior angle θ increases, the overlapping area with the inner segment 61 and the number of overlapping layers also increase when the segment 61 is bent, thereby ensuring uniform welding strength in the radial and circumferential directions and forming a flat bent surface area.

[0295] Preferably, the lower interior angle θ can be determined by the radius of the winding turn on which the segment 61 is located and the width D of the segment 61.

[0296] FIG. 7F is a schematic diagram for explaining the formula for determining the lower interior angle θ of the segment 61.

[0297] Referring to FIG. 7f, ideally, the sides of the segment 61 coincide with the line segments AE and DE that connect the ends A and D of the line segment AD corresponding to the width D of the segment 61 to the core center E.

[0298] When the side of the segment 61 is extended in the most ideal direction, the lower interior angle θ of the segment 61 is refer When it is assumed that the line segment EF is approximately equal to the line segments AE and DE, the width D of the line segment 61 and the radius r of the winding turn on which the line segment 61 is located can be approximately determined using the following equation 4. [Formula 4]

number

[0299] The angle in Equation 4 is the lower interior angle θ of the segment 61 referis an ideal reference angle. Meanwhile, a separation pitch P exists between adjacent segment pieces 61 located on the same winding turn. The length of the separation pitch P is indicated by p. Because the separation pitch P exists between adjacent segment pieces 61, a tolerance of 50% of the separation pitch P can be given to the lower interior angle θ. In other words, the width of the upper end side BC of the segment piece 61 can increase by a maximum of p / 2 to the upper end side B'C'. The lower interior angle θ' reflecting the tolerance can be expressed by the following Equation 5. Lower interior angle θ refer is the ideal reference angle ∠BAG, and the lower interior angle θ' is the angle ∠B'AG' that reflects the tolerance due to the separation pitch P. In Equation 5, H is the height of the segment 61, and p corresponds to the separation pitch. [Formula 5]

number

[0300] Preferably, the lower interior angle θ of the segment 61 located in each winding turn of the electrode assembly may satisfy the following formula 6. As a result, when the segment 61 is bent toward the core center of the electrode assembly, the segment 61 adjacent in the circumferential direction do not interfere with each other, allowing for smooth bending. [Formula 6]

number

[0301] For example, when the electrode 60 forms a wound structure with a diameter of 22 mm and a core radius of 4 mm, the lower interior angle of the segment 61 may increase gradually or stepwise in the range of 60° to 85° in the height variable section.

[0302] As another example, the lower interior angle θ of the plurality of segment pieces 61 may increase gradually or stepwise from the core side to the outer periphery side in units of one or more groups.

[0303] On the other hand, the left lower interior angle and the right lower interior angle of the segment 61 do not have to be equal. Nevertheless, the lower interior angle θ on at least one side can be designed to satisfy the above-mentioned Equation 6.

[0304] Further referring to FIG. 7a, the width d of the first portion B1 B1 The width d of the first portion B1 is designed so that when the third portion B2 is bent toward the core, 90% or more of the core of the electrode assembly is exposed to the outside based on its diameter. B1 may increase in proportion to the bending length of the segment 61 of group 1. The bending length corresponds to the length from the bending point to the upper edge of the segment 61. Preferably, when the electrode 60 is used to manufacture an electrode assembly for a cylindrical battery of form factor 4680, the width d of the first portion B1 B1 can be set to 180 mm to 350 mm depending on the diameter of the core of the electrode assembly and the height of the segment 61 included in group 1.

[0305] The folding points of the segments 61 may be set on a line passing through the lower end of the cutting groove 63 or at a point spaced a predetermined distance above that line. If the segments 61 are folded toward the core at a point spaced a predetermined distance from the lower end of the cutting groove 63, the segments can be more easily overlapped in the radial direction. When the segments 61 are folded, the outer segments press against the inner segments relative to the center of the core. If the folding points are spaced a predetermined distance from the lower end of the cutting groove 63, the inner segments are pressed against the outer segments in the winding axial direction, making it easier to overlap the segments. The separation distance between the folding points is preferably 1 mm or less. Since the minimum height of the segments is 2 mm, the ratio of the separation distance between the folding points to the minimum height may be 50% or less.

[0306] In one example, the width of each segment group can be designed to form the same winding turn of the electrode assembly, where the winding turns can be counted from the end of the first portion B1 of the electrode 60 in its wound state.

[0307] In another variation, the width of each segment group can be designed to comprise at least one winding turn of the electrode assembly.

[0308] In yet another variant, the width and / or height and / or spacing pitch of the segments 61 belonging to the same segment group may increase or decrease gradually and / or stepwise and / or irregularly within a group or between adjacent groups.

[0309] Groups 1 to 8 are merely examples of the segment groups included in the third portion B2. The number of groups, the number of segment segments 61 included in each group, and the width of the group may be adjusted to maximize stress distribution during the bending process of the plain portion 43 and to allow the segment segments 61 to overlap in multiple layers to ensure sufficient welding strength with the current collector.

[0310] In another variation, the height of the second portion B3 may decrease gradually or in steps, similar to the first and second embodiments.

[0311] In yet another variation, the segment structure of the third portion B2 can extend to the second portion B3 (see dotted line). In this case, the second portion B3 can also include multiple segment pieces, similar to the third portion B2. Desirably, the segment structure of the second portion B3 can be substantially identical to the outermost segment group of the third portion B2. In this case, the segment pieces included in the second portion B3 and the third portion B2 can have substantially the same width, height, and spacing pitch. As a variation, the segment pieces of the second portion B3 can have a larger width, height, and / or spacing pitch than the third portion B2.

[0312] In the third part B2, the sections (groups 1 to 7) in which the height of the segments 61 increases stepwise based on the winding direction of the electrode 60 can be defined as segment height variable sections, and the last segment group (group 8) can be defined as a uniform height section in which the height of the segments is maintained uniform.

[0313] That is, in the third portion B2, the height of the segment 61 is h1 to h N When the value increases stepwise from h1 to h N-1The section in which the segment 61 having a height (N is a height index and is a natural number equal to or greater than 2) is arranged corresponds to the height variable section, and h N The section where the segment 61 having a height of 10 mm or less is arranged corresponds to the uniform height section. The ratio of the variable height section and the uniform height section with respect to the length of the electrode 60 in the winding direction will be described later with reference to specific examples.

[0314] When the electrode 60 is used to manufacture an electrode assembly for a cylindrical battery of form factor 4680, the width d of the first portion B1 B1 The width of group 1 may be 35-40% of the width of first portion B1. The width of group 2 may be 130-150% of the width of group 1. The width of group 3 may be 120-135% of the width of group 2. The width of group 4 may be 85-90% of the width of group 3. The width of group 5 may be 120-130% of the width of group 4. The width of group 6 may be 100-120% of the width of group 5. The width of group 7 may be 90-120% of the width of group 6. The width of group 8 may be 115-130% of the width of group 7. The width d of second portion B3 B3 The width of the first portion B1 may be 180 to 350 mm, similar to the width of the first portion B1.

[0315] The reason why the widths of Groups 1 to 8 do not show a consistent increase or decrease pattern is that although the width of the segments gradually increases from Group 1 to Group 8, the number of segments included in a group is limited to an integer, and the thickness of the electrode varies slightly in the winding direction. Therefore, the number of segments may decrease in a particular segment group. Therefore, the width of the group may show an irregular change from the core side to the outer periphery, as shown in the example above.

[0316] That is, when the winding direction widths of three consecutively adjacent segment groups in the circumferential direction of the electrode assembly are W1, W2, and W3, respectively, the combination of segment groups may include one in which W3 / W2 is smaller than W2 / W1.

[0317] In the specific example described above, groups 4 to 6 fall into this case. The width ratio of group 5 to group 4 is 120 to 130%, and the width ratio of group 6 to group 5 is 100 to 120%, which is smaller than 120 to 130%.

[0318] According to yet another variation, when the plain portion 43 of the electrode 60 has a segment structure, the electrode 60 may include a segment-omitted section 64 in which some of the multiple segments are regularly or irregularly omitted, as shown in Figure 7g.

[0319] Preferably, there may be a plurality of segment-omitted sections 64. As one example, the width of the segment-omitted sections 64 may be constant from the core side to the outer periphery side. As another example, the width of the segment-omitted sections 64 may increase or decrease regularly or irregularly from the core side to the outer periphery side. Preferably, the height of the uncoated portion present in the segment-omitted sections 64 may correspond to the height of the first portion B1 and / or the second portion B3.

[0320] The number of the segment segments 61 present between the segment-free sections 64 may be at least one. The electrode 60 may include uncoated sections in which the number of the segment segments 61 present between the segment-free sections 64 increases from the core side to the outer periphery side, as shown in FIG. 7g.

[0321] Preferably, the width of the segment omission section 64 can be set so that when the electrode 60 is wound, the segments located on each winding turn are located within a predetermined independent region 66 relative to the core center C of the electrode assembly 65, as shown in Figure 7h.

[0322] That is, when the electrode assembly 65 is viewed in the winding axis direction, the plurality of segments 61 may be located within a plurality of independent regions 66 based on the core center C. The number of independent regions 66 may vary, such as two, three, four, or five.

[0323] Preferably, the independent regions 66 may be fan-shaped. In this case, the angles between the independent regions 66 may be substantially uniform. Also, the circumferential angle δ of the independent regions 66 may be 20° or greater, optionally 25° or greater, optionally 30° or greater, optionally 35° or greater, or optionally 40° or greater.

[0324] In alternative embodiments, the independent regions 66 may have the form of a geometric figure such as a square, rectangle, parallelogram, trapezoid, or the like.

[0325] In the present invention, the shape of the segment 61 can be varied in various ways.

[0326] FIG. 8a is a plan view showing the structure of an electrode 70 according to a fifth embodiment of the present invention.

[0327] 8a, the electrode 70 of the fifth embodiment has substantially the same configuration as the above-described embodiments except for the shape of the segment 61'. Therefore, unless otherwise specified, the configuration of the fourth embodiment can be applied to the fifth embodiment as well.

[0328] The segment 61' has a geometric shape in which the width of the top and the width of the bottom are substantially the same. Preferably, the segment 61' may be rectangular.

[0329] FIG. 8b is a diagram showing the definition of the width, height and spacing pitch of the rectangular segment 61'.

[0330] 8b, the width D, height H, and spacing pitch P of the divided pieces 61' are set to sufficiently increase the number of overlapping layers of the plain portion 43 to prevent tearing of the plain portion 43 during bending and to improve the welding strength with the current collector, while also preventing abnormal deformation of the plain portion 43. Abnormal deformation refers to the plain portion below the bending point being unable to maintain a straight state and collapsing, resulting in irregular deformation.

[0331] The width D of the segment 61' is defined as the distance between two points where two straight lines extending from both sides of the segment 61' intersect with a straight line extending from the bottom 63a of the cutting groove 63. The height H of the segment 61' is defined as the shortest distance between the top edge of the segment 61' and a straight line extending from the bottom 63a of the cutting groove 63. The spacing pitch P of the segment 61' is defined as the distance between two points where a straight line extending from the bottom 63a of the cutting groove 63 intersects with a straight line extending from the two side edges 63b connected to the bottom 63a. When the side edges 63b and / or the bottom edge 63a are curved, the straight lines may be replaced by tangent lines extending from the side edges 63b and / or the bottom edge 63a at the intersections of the side edges 63b and the bottom edge 63a.

[0332] Preferably, the conditions regarding the width D, height H, and spacing pitch P of the segment 61' are substantially the same as those in the fourth embodiment described above, and therefore, repeated description will be omitted. However, since the segment 61' is rectangular, the interior angle of the lower portion of the segment 61' may be constant at 90°.

[0333] Like the electrode 60 of the fourth embodiment, the electrode 70 of the fifth embodiment may also include a segment-omitted section 64 in which some of the multiple segments are omitted regularly or irregularly, as shown in Figure 8c.

[0334] Also, when an electrode 70 including a segment-omitted section 64 is wound into an electrode assembly, the segments may be positioned within a plurality of independent regions 66 as shown in FIG. 7h.

[0335] When the third portion B2 and the second portion B3 include a plurality of segments 61, 61' as in the fourth and fifth embodiments, the shape of each segment 61, 61' can be variously modified.

[0336] Preferably, the segment can be deformed into various shapes while satisfying at least one of the following conditions:

[0337] Condition 1: The width at the bottom is wider than the width at the top.

[0338] Condition 2: The width of the bottom and the width of the top are equal.

[0339] Condition 3: The width remains the same from bottom to top.

[0340] Condition 4: The width decreases from bottom to top.

[0341] Condition 5: The width decreases and then increases from bottom to top.

[0342] Condition 6: The width increases and then decreases from bottom to top.

[0343] Condition 7: The width increases from bottom to top and then remains constant.

[0344] Condition 8: The width decreases from bottom to top and then remains constant.

[0345] Condition 9: The interior angles on one side of the lower part are the same as the interior angles on the other side.

[0346] Here, the interior angle may be defined as the angle formed by the side of the segment with respect to the width direction of the lower part of the segment. If the side is curved, the interior angle is defined as the angle between the tangent drawn at the lowest point of the curve and the width direction of the lower part of the segment.

[0347] Condition 10: The interior angles on one side of the lower part are different from the interior angles on the other side.

[0348] Condition 11: The interior angle on one side of the lower part and the interior angle on the other side of the lower part are each an acute angle, a right angle, or an obtuse angle.

[0349] Condition 12: Symmetrical with respect to the winding axis direction.

[0350] Condition 13: Asymmetrical with respect to the winding axis direction.

[0351] Condition 14: The sides are straight.

[0352] Condition 15: The side is curved.

[0353] Condition 16: The sides are convex outward.

[0354] Condition 17: The sides are convex inward.

[0355] Condition 18: The upper and / or lower corners are constructed where two straight lines intersect.

[0356] Condition 19: The upper and / or lower corners are structures where straight lines and curves intersect.

[0357] Condition 20: The upper and / or lower corners are structures where curves intersect with each other.

[0358] Condition 21: The top and / or bottom corners are rounded.

[0359] FIG. 9 is a diagram showing an example of the shape of a segment according to a modified example of the present invention.

[0360] As shown in the drawings, the cut pieces may have various geometric shapes with the dotted line connecting the bottoms of the cut grooves on both sides as the base. The geometric shapes may have a structure in which at least one straight line, at least one curved line, or a combination thereof is connected. For example, the cut pieces may have a polygonal shape, a rounded shape, or various shapes that combine these.

[0361] Specifically, the segment can be a symmetric trapezoid (a), an asymmetric trapezoid (b), a parallelogram (c), a triangle (l), a pentagon (k), an arc (e), or an ellipse (f).

[0362] The shape of the segment is not limited to that shown in FIG. 9, and may be modified to other polygonal shapes, other round shapes, or a combination thereof, so long as it satisfies at least one of the above conditions 1 to 21.

[0363] In the polygonal shapes of the segments (a), (b), (c), (k) and (l), the upper and / or lower corners may be straight or rounded (see enlargement of the upper and lower corners in (a)).

[0364] In the polygonal shapes (a), (b), (c), (k), and (l) of the segmented polygons and the round shapes (e) and (f) of the segmented rounds, the interior angle θ1 on one side of the lower part and the interior angle θ2 on the other side can be the same or different, and the interior angle θ1 on one side of the lower part and the interior angle θ2 on the other side can be acute, right, or obtuse. The interior angle is the angle between the base and the side of a geometric figure. When the side is curved, the straight line can be replaced by a tangent extending from the intersection of the base and the side.

[0365] The shape of the sides of the polygonal segment can be varied in various ways.

[0366] As an example, the side of the segment shape (a) can be modified to have a curve that bulges outward as in shape (d), or a curve that concaves inward as in shape (g) or shape (j).

[0367] As another example, the side of the segment (a) may be deformed into a concave fold line, as in the form (h) or (i). Although not shown, the side of the segment (a) may be deformed into a convex fold line, as in the form (h) or (i).

[0368] In the shapes of the segments (d), (g), (j), (h) and (i) whose sides are variously deformed, the interior angle θ1 on one side of the lower part and the interior angle θ2 on the other side may be the same or different, and the interior angle θ1 on one side of the lower part and the interior angle θ2 on the other side may be an acute angle, a right angle or an obtuse angle, respectively.

[0369] The width of the segment may have various change patterns from the bottom to the top.

[0370] As one example, the width of the portion may be maintained constant from bottom to top (form (c)). As another example, the width of the portion may gradually decrease from bottom to top (forms (a), (b), (d), (e), (f), and (g)). As yet another example, the width of the portion may gradually decrease and then increase from bottom to top (forms (i) and (j)). As yet another example, the width of the portion may gradually increase and then decrease from bottom to top (form (k)). As yet another example, the width of the portion may gradually decrease from bottom to top and then remain constant (form (h)). Although not shown, the width of the portion may gradually increase from bottom to top and then remain constant.

[0371] Meanwhile, among the segment shapes exemplified in Figure 9, polygonal shapes with flattened tops may be rotated 180°. For example, when segment shape (a), (b), (d), or (g) is rotated 180°, the width of the segment may gradually increase from bottom to top. For another example, when segment shape (h) is rotated 180°, the width of the segment may remain constant from bottom to top and then gradually increase.

[0372] In the above-described embodiment (variant), according to another aspect of the present invention, the shape of the segments 61, 61' may be changed along the area of the third portion B2. For example, a round shape (e.g., semicircular, elliptical, etc.) that is advantageous for stress dispersion may be applied to the section where stress is concentrated, and a polygonal shape (e.g., square, trapezoid, parallelogram, etc.) with the largest possible area may be applied to the section where stress is relatively low.

[0373] In yet another embodiment, the plurality of segments may have different shapes individually, in groups, or in groups of two or more groups along a direction parallel to the winding direction of the electrode assembly.

[0374] In the above-described embodiment (variant), the division structure of the third portion B2 may be applied to the first portion B1. However, if the division structure is applied to the first portion B1, a reverse forming phenomenon may occur, in which the end of the first portion B1 bends toward the outer periphery when the division pieces 61, 61' of the third portion B2 are bent depending on the curvature radius of the core. Therefore, it is preferable not to apply a division structure to the first portion B1, or, even if a division structure is applied, to adjust the width and / or height and / or spacing pitch of the division pieces 61, 61' to a small level that does not cause reverse forming, taking into account the curvature radius of the core.

[0375] According to yet another aspect of the present invention, after the electrodes 60, 70 are wound into an electrode assembly, the exposed portions at the top and bottom of the electrode assembly may overlap in multiple layers along the radial direction of the electrode assembly to form a folded surface region.

[0376] FIG. 10a is a schematic diagram showing a cross section of a folded surface region F formed by bending a segment 61 toward a core C of an electrode assembly 80. In FIG. 10a, the cross section of the folded surface region F is shown only on the left side based on the winding axis of the electrode assembly 80. The folded surface region F may be formed on both the top and bottom of the electrode assembly 80. FIG. 10b is a perspective view schematically showing an electrode assembly 80 on which a folded surface region F is formed.

[0377] 10a and 10b, the folded surface region F has a structure in which the division segments 61 are stacked in multiple layers in the winding axis direction. The stacking direction is the winding axis direction (Y-axis direction). Section (1) is a division segment-free section (first section B1) where no division segments exist, and sections (2) and (3) are sections where winding turns including the division segments 61 are located. Section (2) is a height-variable section where the height of the division segments 61 varies, and section (3) is a height-uniform section where the height of the division segments is maintained uniform up to the outer periphery of the electrode assembly. As will be described later, the radial lengths of sections (2) and (3) may vary. Meanwhile, the uncoated portion (second section B3) included in at least one winding turn, including the outermost winding turn, may not include a division segment structure. In this case, second section B3 may be excluded from section (3).

[0378] In the section (2), the height of the segment 61 is the radius r1 to r N The minimum height in the section is h1 (=h min ) to maximum height h N (=h max The height variable section where the height of the segment 61 changes is r1 to r N The radius r N From the radius R of the electrode assembly 80, the height of the segment 61 is h N The uniform height means that the deviation in height is within 5%.

[0379] At any radial position in the section (2) and the section (3), the number of stacked segments 61 varies depending on the radial position. The number of stacked segments 61 depends on the width of the section (2), the minimum height h1 and the maximum height h2 of the height-variable section of the segment 61. N , and may vary depending on the height change Δh of the segment 61. The number of stacked segments 61 is the number of segments that intersect with an imaginary line drawn from any radial position of the electrode assembly 80 in the direction of the winding axis.

[0380] Preferably, the number of stacked segments 61 at each position of the folded surface area F can be optimized to suit the required welding strength of the current collector by adjusting the height, width, and spacing pitch of the segment 61 according to the radius of the winding turn containing the segment 61.

[0381] First, when the minimum height h1 of the segment 61 is the same in the height variable section (section (2)) of the segment 61, the maximum height h N How the number of stacked segments 61 changes along the radial direction of the folded surface region F depending on the change in the thickness of the folded surface region F will be described below with reference to a specific example.

[0382] Electrode assemblies of Examples 1-1 to 1-7 were prepared. The electrode assemblies of the Examples had a radius of 22 mm and a core diameter of 4 mm. The positive and negative electrodes included in the electrode assemblies had the electrode structure shown in FIG. 7a. That is, the segment shapes were trapezoidal. The second portions B3 of the positive and negative electrodes did not include the segment. The length of the second portions B3 was 3% to 4% of the total length of the electrode. The positive and negative electrodes and separators were wound using the method described with reference to FIG. 2. The winding turns were 48 to 56 turns, with 51 turns in the Examples. The thicknesses of the positive, negative, and separator were 149 μm, 193 μm, and 13 μm, respectively. The thicknesses of the positive and negative electrodes included the thickness of the active material layer. The thicknesses of the positive and negative current collector plates were 15 μm and 10 μm, respectively. The lengths of the positive electrode and negative electrode in the winding direction are 3948 mm and 4045 mm, respectively.

[0383] In each example, the height variable section (section (2)) of the segment 61 was set to a minimum height of 3 mm so that it started from a radius of 5 mm. In each example, the height of the segment 61 was increased by 1 mm for every 1 mm increase in radius, and the maximum height of the segment 61 was varied from 4 mm to 10 mm.

[0384] Specifically, in Example 1-1, the height variable section (section (2)) of the minute segment 61 is 5 mm to 6 mm, and the height of the minute segment 61 varies from 3 mm to 4 mm. In Example 1-2, the height variable section (section (2)) of the minute segment 61 is 5 mm to 7 mm, and the height of the minute segment 61 varies from 3 mm to 5 mm. In Example 1-3, the height variable section (section (2)) of the minute segment 61 is 5 mm to 8 mm, and the height of the minute segment 61 varies from 3 mm to 6 mm. In Example 1-4, the height variable section (section (2)) of the minute segment 61 is 5 mm to 9 mm, and the height of the minute segment 61 varies from 3 mm to 7 mm. In Example 1-5, the height variable section (section (2)) of the minute segment 61 is 5 mm to 10 mm, and the height of the minute segment 61 varies from 3 mm to 8 mm. In Example 1-6, the height variable section (section (2)) of the segment 61 was 5 mm to 11 mm, and the height of the segment 61 varied from 3 mm to 9 mm. In Example 1-7, the height variable section (section (2)) of the segment 61 was 5 mm to 12 mm, and the height of the segment 61 varied from 3 mm to 10 mm. In Examples 1-1 to 1-7, the height of the segment 61 was uniform from the radius corresponding to the upper limit of the height variable section (section (2)) to the outer periphery. For example, in Example 1-7, the height of the segment 61 was uniform at 10 mm from a radius of 12 mm to 22 mm. In contrast, the electrode assembly of the comparative example maintained the height of the segment 61 at a uniform height of 3 mm from a radius of 5 mm to a radius of 22 mm.

[0385] FIG. 10c is a graph showing the results of counting the number of stacked segments along the radial direction in the folded surface region F of the positive electrode formed on the upper part of the electrode assemblies according to Examples 1-1 to 1-7 and the Comparative Example. Substantially the same results are shown for the folded surface region of the negative electrode. The horizontal axis of the graph represents the radius based on the core center, and the vertical axis of the graph represents the number of stacked segments counted at each radius point. The same applies to FIGS. 10d and 10e, which will be described later.

[0386] Referring to FIG. 10c, a uniform number of layers section b1 of the segment appears in common in Examples 1-1 to 1-7 and Comparative Example 1. The uniform number of layers section b1 is a radial section of a flat region in each graph. The length of the uniform number of layers section b1 increases as the maximum height of the segment decreases, with the uniform number of layers section b1' of the comparative example being the longest. Meanwhile, the number of layers of the segment increases as the maximum height hN of the segment increases. That is, as the maximum height hN of the segment increases and the width of the height-variable section (section (2)) of the segment increases, the number of layers of the segment increases, while the width of the uniform number of layers section b1 decreases. Outside the uniform number of layers section b1, a decreasing number of layers section b2 appears, in which the number of layers of the segment decreases as the radius increases. The decreasing number of layers section b2 is a radial section in which the number of layers of the segment decreases as the radius of the electrode assembly increases. The uniform number of layers section b1 and the decreasing number of layers section b2 are adjacent in the radial direction and are complementary to each other. That is, as the length of one section increases, the length of the other section decreases. In the stack number decreasing section b2, the amount of decrease in the number of stacks is proportional to the distance from the stack number uniform section b1.

[0387] In terms of the number of stacked segments, Examples 1-1 to 1-7 have 10 or more stacked segments in the uniform stacked segment number section b1. The region where the number of stacked segments is 10 or more can be set as a desirable welding target region. The welding target region is a section where at least a portion of the current collector is welded.

[0388] In Examples 1-1 to 1-7, the uniform number of layers section b1 starts at the radial point where the height variable section (section (2)) of the segment starts. That is, the height variable section (section (2)) starts at a radius of 5 mm and extends toward the outer periphery.

[0389] Table 4 below shows the results of calculating the ratio of the length of the segment-free section (c, section (1) in Figure 10a) to the radius (ba) of the electrode assembly excluding the core for the positive electrode in Examples 1-1 to 1-7 and Comparative Example 1; the ratio (e / f) of the length of the uniform number of stacks section b1 to the length (f) from the radius point (5 mm) where the uniform number of stacks section begins to the outermost point (22 mm) of the electrode assembly; the ratio (d / f) of the length of the variable height section (d) of the segment to the length (f) from the radius point (5 mm) where the uniform number of stacks section begins to the outermost point (22 mm) of the electrode assembly; the ratio (h) of the length of the electrode region corresponding to the segment-free section (first part B1) to the entire length of the electrode; the ratio (i) of the length of the electrode region corresponding to the variable height section to the entire length of the electrode; and the ratio (j) of the electrode region corresponding to the uniform height section to the entire length of the electrode.

[0390] The negative electrode has substantially the same parameters as the positive electrode, except for a difference of 0.1 to 1.2% in parameter h. The sum of the ratios h, i, and j is slightly different from 100%. This is because there is a section without a segment in the second portion B3, which corresponds to the outer uncoated portion of the electrode. For example, in Example 1-1, there is no segment in the second portion B3, which corresponds to approximately 4% of the total length of the electrode. In Table 4, a to f are parameters based on the radial length, and h, i, and j are parameters based on the longitudinal direction of the electrode before it is wound into an electrode assembly. Furthermore, parameters corresponding to ratios (%) are rounded to the nearest tenth. This is also true for Tables 5 and 6, which will be described later. [Table 4]

[0391] Referring to Examples 1-1 to 1-7 in Table 4, the number of laminations of the segment segments ranged from 11 to 26, and the ratio (d / f) of the variable height section (d) to the radius section (f) containing the segment segments ranged from 6% to 41%. The ratio (e / f) of the uniform lamination number section (e) to the radius section (f) containing the segment segments ranged from 47% to 82%. The ratio (c / (ba)) of the segment-free section (c, section (1) in FIG. 10a) to the radius (ba) of the electrode assembly excluding the core was 15%. The ratio of the length of the electrode region corresponding to the segment-free section (first portion B1) to the overall length of the electrode was 6%, the ratio of the length of the electrode region corresponding to the variable height section to the overall length of the electrode was 3% to 32%, and the ratio of the length of the electrode region corresponding to the uniform height section to the overall length of the electrode was 59% to 87%. The number of laminations (g) of the uniform lamination number section was 10 or more in all Examples 1-1 to 1-7. The uniform number of layers section (e) decreases as the variable height section (d) of the segment increases, but the number of layers (g) of the segment increases in the uniform number of layers section (e). Preferably, the uniform number of layers section (e) where the number of layers of the segment (g) is 10 or more can be set as the welding target area.

[0392] Cylindrical batteries with 1865 and 2170 form factors have an electrode assembly radius of approximately 9 mm to 10 mm. Therefore, in conventional cylindrical batteries, the radial length of the segment section (f) cannot be maintained at 17 mm, as in Examples 1-1 to 1-7, and the length of the uniform stack number section (e), where the number of segment stacks is 10 or more, cannot be maintained at 8 mm to 14 mm. This is because, in conventional cylindrical batteries, if the core radius is designed to be 2 mm as in Examples 1-1 to 1-7, the radial section in which the segment can be arranged is essentially only 7 mm to 8 mm. Furthermore, in conventional cylindrical batteries, the length of the electrode in the winding direction is approximately 600 mm to 980 mm. This short electrode length is only approximately 15% to 24% of the length of the electrodes used in Examples 1-1 to 1-7 (positive electrode: 3948 mm, negative electrode: 4045 mm). Therefore, the numerical ranges for the parameters h, i, and j cannot be easily derived from the design specifications of conventional cylindrical batteries.

[0393] Next, we will use a specific example to explain how the number of stacked segments changes along the radial direction of the folded surface area F when the maximum height hN of the segment is the same in the segment height variable section (section (2) in Figure 10a) as the minimum height h1 of the segment changes.

[0394] The electrode assemblies of Examples 2-1 to 2-5 have a radius of 22 mm and a diameter of the core C of 4 mm. The minimum height h1 of the height variable section (section (2) in FIG. 10a) of the segment 61 is 4 mm, and the maximum height h N was varied in 1 mm increments from 6 mm to 10 mm. Therefore, in the electrode assemblies of Examples 2-1 to 2-5, the widths of the section with variable segment height (section (2) in FIG. 10a) were 2 mm, 3 mm, 4 mm, 5 mm, and 6 mm, respectively, and the section without segment (section (1) in FIG. 10a) was a radius section ranging from 2 mm to 6 mm.

[0395] The electrode assemblies of Examples 3-1 to 3-4 have a radius of 22 mm and a diameter of the core C of 4 mm. The minimum height h1 of the height variable section (section (2) in FIG. 10a) of the segment 61 is equal to 5 mm, and the maximum height h N was varied in 1 mm increments from 7 mm to 10 mm. Therefore, in the electrode assemblies of Examples 3-1 to 3-4, the widths of the section with variable segment height (section (2) in FIG. 10a) were 2 mm, 3 mm, 4 mm, and 5 mm, respectively, and the section without segment (section (1) in FIG. 10a) was a radius section ranging from 2 mm to 7 mm.

[0396] The electrode assemblies of Examples 4-1 to 4-3 have a radius of 22 mm and a diameter of the core C of 4 mm. The minimum height h1 of the height variable section (section (2) in FIG. 10a) of the segment 61 is 6 mm, and the maximum height h N was varied in 1 mm increments from 8 mm to 10 mm. Therefore, in the electrode assemblies of Examples 4-1 to 4-3, the widths of the section with variable segment height (section (2) in FIG. 10a) were 2 mm, 3 mm, and 4 mm, respectively, and the section without segment (section (1) in FIG. 10a) was a radius section ranging from 2 mm to 8 mm.

[0397] The electrode assemblies of Examples 5-1 and 5-2 have a radius of 22 mm and a diameter of the core C of 4 mm. The minimum height h1 of the height variable section (section (2) in FIG. 10a) of the segment 61 is 7 mm, and the maximum height h N was varied in 1 mm increments from 9 mm to 10 mm. Therefore, in the electrode assemblies of Examples 5-1 and 5-2, the widths of the section with variable segment height (section (2) in FIG. 10a) were 2 mm and 3 mm, respectively, and the section without segment (section (1) in FIG. 10a) was a radius section ranging from 2 mm to 9 mm.

[0398] 10d is a graph showing the results of counting the number of stacked sections measured along the radial direction in the folded surface region F of the positive electrode formed on the upper part of the electrode assemblies according to Examples 2-1 to 2-5, 3-1 to 3-4, 4-1 to 4-3, 5-1, and 5-2. Substantially the same results are shown for the folded surface region of the negative electrode.

[0399] In Figure 10d, graph (a) shows the results of counting the number of stacked pieces along the radial direction in the folded surface region F for Examples 2-1 to 2-5, graph (b) shows the results of counting the number of stacked pieces along the radial direction in the folded surface region F for Examples 3-1 to 3-4, graph (c) shows the results of counting the number of stacked pieces along the radial direction in the folded surface region F for Examples 5-1 and 5-2.

[0400] Referring to FIG. 10d, the uniform number of layers section b1 of the sub-segment appears in all examples. The uniform number of layers section b1 is a radius section of a flat area in the graph. The length of the uniform number of layers section b1 is determined by the maximum height h1 of the sub-segment when the minimum height h1 of the sub-segment is the same. N The length of the uniform stacking section b1 is the maximum height h of the N When the number of layers is the same, the number of layers of the sub-segment increases as the minimum height h1 of the sub-segment decreases. N In the example, a section b2 with a decreased number of layers appears adjacent to a section b1 with a uniform number of layers.

[0401] In the embodiment, the number of layers of the segment in the uniform layer number section b1 is all equal to or greater than 10. The region where the number of layers of the segment is equal to or greater than 10 can be set as a desirable welding target region.

[0402] In the examples, the uniform number of layers section b1 starts at the radial point where the variable height section of the sub-segment (section (2) in FIG. 10a) starts. In examples 2-1 to 2-5, the variable height section of the sub-segment (section (2) in FIG. 10a) starts at 6 mm and extends toward the outer periphery. In examples 3-1 to 3-4, the variable height section of the sub-segment (section (2) in FIG. 10a) starts at 7 mm and extends toward the outer periphery. In examples 4-3 to 4-3, the variable height section of the sub-segment (section (2) in FIG. 10a) starts at 8 mm and extends toward the outer periphery. In examples 5-1 and 5-2, the variable height section of the sub-segment (section (2) in FIG. 10a) starts at 9 mm and extends toward the outer periphery.

[0403] Table 5 below shows the results of calculating various parameters for Examples 2-1 to 2-5, Examples 3-1 to 3-4, Examples 4-1 to 4-3, Examples 5-1 and 5-2, including the ratio (e / f) of the length of the uniform stack count section to the length from the radius point (6 mm, 7 mm, 8 mm, 9 mm) where the uniform stack count section begins to the outermost point (22 mm) of the electrode assembly, and the ratio (d / f) of the length of the variable height section (section (2)) of the segment to the length from the radius point (6 mm, 7 mm, 8 mm, 9 mm) where the uniform stack count section begins to the outermost point (22 mm) of the electrode assembly. [Table 5]

[0404] Referring to Examples 2-5, 3-4, 4-3, and 5-2 in Table 5 along with Figures 10a and 10d, the maximum height hN of the segment in the variable height section (Section (2)) of the segment is the same at 10 mm, but the minimum height h1 of the segment increases by 1 mm from 4 mm, 5 mm, 6 mm, and 7 mm, and the length of the variable height section (Section (2)) decreases by 1 mm from 6 mm, 5 mm, 4 mm, and 3 mm. In the four examples, the ratio (e / f) of the uniform stacking number section is the highest in Example 2-5 at 69% and the lowest in Example 5-2 at 38%, and the number of stacks in the uniform stacking number section is all the same. From the results shown in Table 5, the maximum height h of the segment is 10 mm. N When the minimum height h1 of the sub-segment is the same, as the width of the variable height section (section (2)) of the sub-segment decreases and the width of the uniform number of layers section increases, the width of the uniform number of layers section also increases proportionally. This is because as the minimum length h1 of the sub-segment decreases, the radius point where the sub-segment starts approaches the core side, and the area where the sub-segments are stacked expands toward the core side.

[0405] Referring to Table 5, the number of laminations of the segment is 16 to 26, the ratio (d / f) of the segment height variable section (section (2)) is 13% to 38%, and the ratio (e / f) of the uniform lamination section is 31% to 69%. The ratio (c / (ba)) of the segment-free section (section (1)) to the radius (ba) of the electrode assembly excluding the core is 20% to 35%. The ratio of the length of the electrode region corresponding to the segment-free section (section (1)) to the overall length of the electrode is 10% to 20%, the ratio of the length of the electrode region corresponding to the height variable section (section (2)) to the overall length of the electrode is 6% to 25%, and the ratio of the length of the electrode region corresponding to the uniform height section (section (3)) to the overall length of the electrode is 62% to 81%.

[0406] Cylindrical batteries with 1865 and 2170 form factors have an electrode assembly radius of approximately 9 mm to 10 mm. Therefore, unlike the embodiment, the radial length of the segment section (f) cannot be secured at 13 mm to 16 mm. The length of the segment-free section (c, section (1)) cannot be secured at 4 mm to 7 mm, while the length of the uniform-number section (e) with 10 or more segment stacks cannot be secured at 5 mm to 11 mm. This is because, in a conventional cylindrical battery, if the core radius is designed to be 2 mm as in the embodiment, the radius section in which segment sections can be arranged is essentially only 7 mm to 8 mm. Furthermore, in a conventional cylindrical battery, the length of the electrode in the winding direction is approximately 600 mm to 980 mm. This short electrode length is only approximately 15% to 24% of the electrode length in the embodiment (3948 mm for the positive electrode and 4045 mm for the negative electrode). Therefore, the numerical ranges for the parameters h, i, and j cannot be easily derived from the design specifications of conventional cylindrical batteries.

[0407] Next, in the variable height section (section (2)) of the subsection, the minimum height h1 and the maximum height h N When the diameter of the core C of the electrode assembly is the same, how the number of laminations of the segmented pieces changes along the radial direction of the folded surface area F will be explained using a specific example.

[0408] The electrode assemblies of Examples 6-1 to 6-6 have a radius of 22 mm, and the radius of the core C is 4 mm. The minimum height h1 of the segment 61 in the height variable section (section (2)) is 3 mm, and the maximum height h N was varied in 1 mm increments from 5 mm to 10 mm. Therefore, in the electrode assemblies of Examples 6-1 to 6-6, the width of the section (section (2)) in which the height of the segment was variable was 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, and 7 mm, respectively, and the section (section (1)) in which no segment was present was a radius section ranging from 4 mm to 7 mm.

[0409] The electrode assemblies of Examples 7-1 to 7-6 have a radius of 22 mm, and the radius of the core C is 2 mm. The minimum height h1 of the segment 61 in the height variable section (section (2)) is 3 mm, and the maximum height h N was varied in 1 mm increments from 5 mm to 10 mm. Therefore, in the electrode assemblies of Examples 7-1 to 7-6, the width of the section (section (2)) in which the height of the segment was variable was 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, and 7 mm, respectively, and the section (section (1)) in which no segment was present was the same as the radius section from 2 mm to 5 mm.

[0410] 10e is a graph showing the results of counting the number of stacked sections measured along the radial direction in the folded surface region F of the positive electrode formed on the upper part of the electrode assemblies according to Examples 6-1 to 6-6 and 7-1 to 7-6. Substantially the same results are shown for the folded surface region of the negative electrode.

[0411] In FIG. 10e, graph (a) shows the results of counting the number of stacked pieces along the radial direction in the folded surface region F for Examples 6-1 to 6-6, and graph (b) shows the results of counting the number of stacked pieces along the radial direction in the folded surface region F for Examples 7-1 to 7-6.

[0412] Referring to FIG. 10e, the uniform number of layers section b1 of the segment appears in all examples. The uniform number of layers section b1 is a radial section of a flat area in the graph. The radial length of the uniform number of layers section b1 is the same as the maximum height h1 of the segment when the minimum height h1 of the segment is the same. N On the other hand, in the uniform stacking section b1, the number of stacks of the sub-section increases as the maximum height h N In the example, a section b2 with a reduced number of layers is observed adjacent to the section b1 with a uniform number of layers.

[0413] In the embodiment, the number of layers of the segment in the uniform layer number section b1 is all equal to or greater than 10. The region where the number of layers of the segment is equal to or greater than 10 can be set as a desirable welding target region.

[0414] In the examples, the uniform number of layers section b1 starts at the radius where the variable height section (section (2)) of the segment starts. In Examples 6-1 to 6-6, the radius where the variable height section (section (2)) of the segment starts is 7 mm, and in Examples 7-1 to 7-6, the radius where the variable height section (section (2)) of the segment starts is 5 mm.

[0415] Table 6 below shows the calculation results of various parameters for Examples 6-1 to 6-6 and Examples 7-1 to 7-6, including the ratio (e / f) of the length of the uniform stack count section to the length from the radius point (7 mm, 5 mm) where the uniform stack count section begins to the outermost point (22 mm) of the electrode assembly, and the ratio (d / f) of the length of the variable height section (section (2)) of the segment to the length from the radius point (7 mm, 5 mm) where the uniform stack count section begins to the outermost point (22 mm) of the electrode assembly. [Table 6]

[0416] Referring to FIG. 10a and Examples 6-6 and 7-6 in Table 6, the minimum height h1 and maximum height h2 of the segment in the height variable section (section (2)) of the segment are Nare the same, at 3 mm and 10 mm, respectively. However, Example 6-6 has a core radius 2 mm larger than Example 7-6. Therefore, Example 6-6 has a uniform lamination count section (e) and a segment section (f) 2 mm smaller than Example 7-6, but the number of laminations in the segment in the uniform lamination count section is the same. This result is due to the difference in core radius. From the results shown in Table 6, it can be seen that when the width of the variable height section (section (2)) of the segment is the same, as the core radius (a) becomes smaller, the ratio (d / f) of the variable height section (section (2)) decreases while the ratio (e / f) of the uniform lamination count section increases. Referring to Table 6, it can be seen that the number of laminations in the segment ranges from 13 to 26, the ratio (d / f) of the variable height section (section (2)) of the segment ranges from 12% to 47%, and the ratio (e / f) of the length of the uniform lamination count section ranges from 40% to 76%. The ratio (c / (ba)) of the segment-free section (section (1)) to the radius (ba) of the electrode assembly excluding the core is 15% to 17%. The ratio of the length of the electrode region corresponding to the segment-free section (section (1)) to the overall length of the electrode is 6%, the ratio of the length of the electrode region corresponding to the height-variable section (section (2)) to the overall length of the electrode is 7% to 32%, and the ratio of the length of the electrode region corresponding to the height-uniform section (section (3)) to the overall length of the electrode is 59% to 83%.

[0417] Cylindrical batteries with 1865 and 2170 form factors have an electrode assembly radius of approximately 9 mm to 10 mm. Therefore, unlike the embodiment, the radial length of the segment section (f) cannot be secured at 15 mm to 17 mm. The length of the segment-free section (section (1)) cannot be secured at approximately 3 mm, while the length of the uniform-number section (e) with 10 or more segment stacks cannot be secured at 6 mm to 13 mm. This is because, in conventional cylindrical batteries, if the core radius is designed to be 2 mm to 4 mm as in the embodiment, the radius section in which segment sections can be arranged is essentially only 5 mm to 8 mm. Furthermore, in conventional cylindrical batteries, the winding direction length of the electrodes is approximately 600 mm to 980 mm. This short electrode length is only approximately 15% to 24% of the electrode length in the embodiment (3948 mm for positive electrode and 4045 mm for negative electrode). Therefore, the numerical ranges for the parameters h, i, and j cannot be easily derived from the design specifications of conventional cylindrical batteries.

[0418] Considering the data in Tables 4 to 6 comprehensively, the number of layered segments in the uniform layered segment section may be 11 to 26. The ratio (d / f) of the variable layered segment section (section (2)) may be 6% to 47%. The ratio (e / f) of the uniform layered segment section may be 31% to 82%. The ratio (c / (ba)) of the length of the layered segment-free section (section (1)) to the radius of the electrode assembly excluding the core may be 15% to 35%. The ratio of the length of the electrode region corresponding to the layered segment-free section (section (1)) to the overall length of the electrode (length in the winding direction) may be 6% to 20%. The ratio of the length of the electrode region corresponding to the variable layered segment section (section (2)) to the overall length of the electrode may be 3% to 32%. The ratio of the length of the electrode region corresponding to the uniform layered segment section (section (3)) to the overall length of the electrode may be 59% to 87%.

[0419] Meanwhile, the parameters described in Tables 4 to 6 may vary depending on design factors including the radius of the core (a); the radius of the electrode assembly (b); the minimum height h1 and maximum height hN in the variable height section (section (2)) of the segment; the change in height Δh of the segment per 1 mm increase in radius; and the thicknesses of the positive electrode, negative electrode, and separator.

[0420] Therefore, the number of layered segments in the uniform layered segment section can be expanded to 10 to 35. The ratio (d / f) of the variable layered segment section (section (2)) can be expanded to 1% to 50%. The ratio (e / f) of the uniform layered segment section can be expanded to 30% to 85%. The ratio (c / (ba)) of the length of the layered segment-free section (section (1)) to the radius of the electrode assembly excluding the core can be expanded to 10% to 40%. The ratio of the length of the electrode region corresponding to the layered segment-free section (section (1)) to the overall length of the electrode (length in the winding direction) can be expanded to 1% to 30%. The ratio of the length of the electrode region corresponding to the variable layered segment section (section (2)) to the overall length of the electrode can be expanded to 1% to 40%. The ratio of the length of the electrode region corresponding to the uniform layered segment section (section (3)) to the overall length of the electrode can be expanded to 50% to 90%. In the above-described embodiment, the maximum height h of the segment included in the height variable section (section (2)) and the height uniform section (section (3)) is N The height index N of each electrode assembly is between 2 and 8. For example, referring to Table 4, the height index N for Examples 1-1 and 1-7 is 2 and 8, respectively. However, the height index N may vary depending on the height change amount Δh of the segment in the radial direction of the electrode assembly. When the radial length of the height variable section (Section (2)) is fixed, as the height change amount Δh of the segment decreases, the height index N increases, and vice versa is also possible. Preferably, the height index N can be further extended to between 2 and 20, and optionally to between 2 and 30.

[0421] In the folded surface regions F formed on the upper and lower parts of the electrode assembly, the lamination number uniform sections can be used as welding target regions of the current collector.

[0422] Preferably, the welding area of the current collector overlaps the uniform lamination number section in the radial direction of the electrode assembly by at least 50%, and the higher the overlap ratio, the more preferable.

[0423] Preferably, the other region of the welding region of the current collector that does not overlap with the uniform lamination number section may overlap with the reduced lamination number section adjacent to the uniform lamination number section in the radial direction.

[0424] More preferably, other regions of the welding region of the current collector that do not overlap with the uniform lamination number section may overlap with regions of the reduced lamination number section where the overlap number of the divided segments is 10 or more.

[0425] Welding the current collector to the region where the number of laminated segments is 10 or more is desirable in terms of weld strength and in preventing damage to the separator and active material layer during welding, and is particularly useful when welding the current collector using a high-power laser with high transmission characteristics.

[0426] When a uniform stacking section, in which 10 or more divided pieces are stacked, is welded to a current collector using a laser, even if the laser output is increased to improve welding quality, the uniform stacking section absorbs most of the laser energy to form a weld bead, preventing damage to the separator and active material layer below the folded surface region F by the laser.

[0427] In addition, the area irradiated with the laser has 10 or more stacked pieces, so the weld beads are formed with sufficient volume and thickness, ensuring sufficient weld strength and reducing the resistance of the weld interface to a level suitable for fast charging.

[0428] The laser power used to weld the current collector can be determined by the desired weld strength between the folded surface region F and the current collector. The weld strength increases in proportion to the number of stacked segments. This is because the greater the number of stacked segments, the larger the volume of the weld bead formed by the laser. The weld bead is formed as the current collector material and the segment material are melted together. Therefore, a larger volume of the weld bead provides a stronger bond between the current collector and the folded surface region, lowering the contact resistance at the weld interface.

[0429] Preferably, the welding strength is 2 kgf / cm 2 More preferably, 4kgf / cm 2 The maximum welding strength may vary depending on the output of the laser welding device. As an example, the welding strength is preferably 8 kgf / cm. 2 Less than 6kgf / cm, more preferably 2 The following may be set: However, the present invention is not limited to this.

[0430] When the weld strength satisfies the above numerical range, the physical properties of the weld interface do not deteriorate even when the electrode assembly is subjected to severe vibrations in the winding axial direction and / or radial direction, and the resistance of the weld interface can also be reduced due to the sufficient volume of the weld beads.

[0431] The laser output required to meet the welding strength requirements varies depending on the laser device, but can be appropriately adjusted within the range of 250W to 320W or 40% to 100% of the maximum laser output specification provided by the device.

[0432] The weld strength is the tensile force per unit area of the current collector (kgf / cm) when the current collector begins to separate from the folded surface area F. 2 ) can be defined as the weld strength. Specifically, after welding of the current collector is completed, a tensile force is applied to the current collector and the magnitude of the force is gradually increased. When the tensile force exceeds a critical value, the pieces begin to separate from the weld interface. At this time, the tensile force applied to the current collector divided by the area of the current collector corresponds to the weld strength.

[0433] The folded surface region F is formed by stacking a plurality of layers of segment pieces, and according to the above-described embodiment, the number of stacked segment pieces can be increased from a minimum of 10 to a maximum of 35.

[0434] The thickness of the positive electrode current collector (foil) constituting the uncoated portion 43 may be 10 μm to 25 μm, and the thickness of the negative electrode current collector (foil) constituting the uncoated portion 43 may be 5 μm to 20 μm. Therefore, the folded surface region F of the positive electrode may include a region where the total laminated thickness of the divided pieces is 100 μm to 875 μm. Also, the folded surface region F of the negative electrode may include a region where the total laminated thickness of the divided pieces is 50 μm to 700 μm.

[0435] FIG. 10f is a top view of an electrode assembly showing a uniform lamination number section b1 and a reduced lamination number section b2 in the bent surface region F of the divided segments 61 and 61' according to an embodiment of the present invention.

[0436] Referring to Figure 10f, the area between the two circles indicated by the thick solid lines corresponds to the folded surface area F of the segment, the area between the two circles indicated by the dotted line corresponds to the uniform layer count section b1 where the number of layers of the segment is 10 or more, and the area outside the uniform layer count section b1 corresponds to the reduced layer count section b2.

[0437] As an example, the current collector P c is welded to the folded surface area F, the current collector P c Welding pattern W on the surface p is generated. Welding pattern W p can be an array of line or dot patterns. p corresponds to the welding area and can overlap with the uniform number of layers section b1 of the divided section along the radial direction by 50% or more. Therefore, the welding pattern W p A part of the layer count uniformity section b1 is included, and the remaining welding pattern W p The welding pattern W can be included in the layer number decreasing section b2 outside the layer number uniform section b1. Of course, in order to maximize the welding strength and reduce the resistance of the welding area, p The entirety can overlap with the uniform stack number section b1.

[0438] The area of the folded surface region F can be defined as the sum of the area of the uniform lamination number section b1 and the area of the reduced lamination number section b2 of the divided segment. The ratio (e / f) of the uniform lamination number section b1 is 30% to 85%, preferably 31% to 82%, so the ratio of the area of the uniform lamination number section b1 to the area of the folded surface region F can be 9% (302 / 1002) to 72% (852 / 1002), preferably 10% (312 / 1002) to 67% (822 / 1002).

[0439] Preferably, the current collector P c The ends of the portions in contact with the folded surface region F may cover the ends of the partial segments 61, 61' bent toward the core C in the final winding turn of the uniform height section (section (3)). In this case, the partial segments 61, 61' are bent toward the current collector P. c The welding pattern W is pressed by p is formed, the current collector P c and the folded surface region F are strongly bonded. As a result, the divided pieces 61, 61' stacked in the winding axis direction are tightly adhered to each other, which reduces the resistance at the welding interface and prevents the divided pieces 61, 61' from lifting up.

[0440] Meanwhile, the bending direction of the segment pieces may be opposite to the above-described direction. That is, the segment pieces may be bent from the core side toward the outer periphery. In this case, the pattern in which the height of the segment pieces changes along the winding direction (X-axis direction) may be opposite to that of the above-described embodiment (variant). For example, the height of the segment pieces may decrease stepwise from the core side toward the outer periphery. In addition, the structure applied to the first portion B1 and the structure applied to the second portion B3 may be switched. Preferably, the height of the segment pieces may be gradually decreased from the core side toward the outer periphery, and the height change pattern of the segment pieces may be designed so that when the segment piece closest to the outer periphery of the electrode assembly is bent toward the outer periphery, the end of the segment piece does not protrude outside the outer periphery of the electrode assembly.

[0441] The electrode structure of the above-described embodiment (variant) may be applied to at least one of the first and second electrodes of different polarities included in a jelly roll type or other type of electrode assembly known in the art. Furthermore, when the electrode structure of the embodiment (variant) is applied to one of the first and second electrodes, a conventional electrode structure may be applied to the other. Furthermore, the electrode structures applied to the first and second electrodes may not be the same, but may be different.

[0442] As an example, when the first electrode and the second negative electrode are a positive electrode and a negative electrode, respectively, any one of the embodiments (variants) may be applied to the first electrode, and a conventional electrode structure (see FIG. 1) may be applied to the second electrode.

[0443] As another example, when the first electrode and the second electrode are a positive electrode and a negative electrode, respectively, any one of the embodiments (variants) may be selectively applied to the first electrode, and any one of the embodiments (variants) may be selectively applied to the second electrode.

[0444] In the present invention, the positive electrode active material coated on the positive electrode and the negative electrode active material coated on the negative electrode may be any active material known in the art without any limitation.

[0445] As an example, the positive electrode active material may be represented by the general chemical formula A (A x M y )O 2+z (A includes at least one element of Li, Na, and K; M includes at least one element selected from Ni, Co, Mn, Ca, Mg, Al, Ti, Si, Fe, Mo, V, Zr, Zn, Cu, Al, Mo, Sc, Zr, Ru, and Cr; x≧0, 1≦x+y≦2, −0.1≦z≦2; the stoichiometric coefficients x, y, and z are selected to maintain electroneutrality of the compound).

[0446] As another example, the positive electrode active material may be an alkali metal compound xLiM disclosed in U.S. Pat. No. 6,677,082, U.S. Pat. No. 6,680,143, etc. 1 O2-(1-x)Li2M 2 O3(M1 contains at least one element having an average oxidation state of 3; M 2 contains at least one element having an average oxidation state of 4; 0 ≦ x ≦ 1) can be.

[0447] As another example, the positive electrode active material is generally represented by the chemical formula Li a M 1 x Fe 1-x M 2 y P 1-y M 3 z O 4-z (M 1 contains at least one element selected from Ti, Si, Mn, Co, Fe, V, Cr, Mo, Ni, Nd, Al, Mg and Al; M 2 contains at least one element selected from Ti, Si, Mn, Co, Fe, V, Cr, Mo, Ni, Nd, Al, Mg, Al, As, Sb, Si, Ge, V and S; M 3 contains a halogen group element selectively containing F; 0 < a ≦ 2, 0 ≦ x ≦ 1, 0 ≦ y < 1, 0 ≦ z < 1; the stoichiometric coefficients a, x, y and z are selected so that the compound maintains electrical neutrality), or it can be a lithium metal phosphate represented by Li3M2(PO4)3 [M contains at least one element selected from Ti, Si, Mn, Fe, Co, V, Cr, Mo, Ni, Al, Mg and Al].

[0448] Preferably, the positive electrode active material may contain primary particles and / or secondary particles in which the primary particles are aggregated.

[0449] As an example, as the negative electrode active material, a carbon material, a lithium metal or a lithium metal compound, silicon or a silicon compound, tin or a tin compound, etc. can be used. Metal oxides such as TiO2 and SnO2 with a potential of less than 2V can also be used as the negative electrode active material. As the carbon material, both low-crystalline carbon and high-crystalline carbon can be used.

[0450] The separator may be a porous polymer film, for example, a porous polymer film made of a polyolefin polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, an ethylene / methacrylate copolymer, etc., either alone or in a laminate. Alternatively, the separator may be a conventional porous nonwoven fabric, for example, a nonwoven fabric made of high-melting-point glass fiber, polyethylene terephthalate fiber, etc.

[0451] At least one surface of the separator may include a coating layer of inorganic particles. Alternatively, the separator itself may be made of a coating layer of inorganic particles. The particles constituting the coating layer may have a structure in which they are bound with a binder so that there is interstitial volume between adjacent particles.

[0452] The inorganic particles may be made of an inorganic material having a dielectric constant of 5 or more. Non-limiting examples of the inorganic particles include Pb(Zr,Ti)O3 (PZT), Pb 1-x La x Zr 1-y Ti y O3(PLZT), PB(Mg3Nb 2 / 3 )O3-PbTiO3 (PMN-PT), BaTiO3, hafnia (HfO2), SrTiO3, TiO2, Al2O3, ZrO2, SnO2, CeO2, MgO, CaO, ZnO, and Y2O3.

[0453] Hereinafter, the structure of an electrode assembly according to an embodiment of the present invention will be described in detail.

[0454] FIG. 11 is a cross-sectional view of a jelly-roll type electrode assembly 80 in which the electrode 40 of the first embodiment is applied to a first electrode (positive electrode) and a second electrode (negative electrode), taken along the Y-axis direction (winding axis direction).

[0455] The electrode assembly 80 can be manufactured using the winding method described with reference to Figure 2. For ease of explanation, the protruding structures of the first uncoated portion 43a and the second uncoated portion 43b extending outward from the separator are shown in detail, and the winding structures of the first electrode, the second electrode, and the separator are not shown. The first uncoated portion 43a protruding upward extends from the first electrode, and the second uncoated portion 43b protruding downward extends from the second electrode.

[0456] The varying heights of the first and second uncoated regions 43a and 43b are shown only schematically. That is, the height of the uncoated regions may vary irregularly depending on the cutting position of the cross section. For example, if the sides of the trapezoidal segments 61 and 61' or the cutting grooves 63 are cut, the height of the uncoated regions in the cross section will be lower than the height H of the segments 61 and 61'. Therefore, it should be understood that the height of the uncoated regions shown in the cross-sectional views of the electrode assembly corresponds to the average height (H in FIGS. 7b and 8b) of the uncoated regions included in each winding turn.

[0457] Referring to FIG. 11, the first uncoated portion 43a includes a first portion B1 adjacent to the core of the electrode assembly 80, a second portion B3 adjacent to the outer peripheral surface of the electrode assembly 80, and a third portion B2 interposed between the first portion B1 and the second portion B3.

[0458] The height (length in the Y-axis direction) of the second portion B3 is relatively shorter than the height of the third portion B2, which prevents the beading portion and the second portion B3 from coming into contact with each other and causing an internal short circuit when the beading portion of the battery housing is pressurized near the second portion B3.

[0459] The second uncoated portion 43b has the same structure as the first uncoated portion 43a. In one variation, the second uncoated portion 43b may have a conventional electrode structure or an electrode structure of another embodiment (variation).

[0460] The end 81 of the first uncoated portion 43a and the end 81 of the second uncoated portion 43b may be bent in the radial direction of the electrode assembly 80, for example, from the outer periphery toward the core. In this case, the second portion B3 may not be substantially bent.

[0461] FIG. 12 is a cross-sectional view of a jelly roll type electrode assembly 90 in which the electrode 45 of the second embodiment is applied to the first electrode (positive electrode) and the second electrode (negative electrode), taken along the Y-axis direction (winding axis direction).

[0462] Referring to FIG. 12, the first uncoated portion 43a of the first electrode includes a first portion B1 adjacent to the core of the electrode assembly 90, a second portion B3 adjacent to the outer peripheral surface of the electrode assembly 90, and a third portion B2 interposed between the first portion B1 and the second portion B3.

[0463] The height of the second portion B3 is relatively lower than the height of the third portion B2, and decreases gradually or in steps from the core side to the outer periphery side, thereby preventing the beading portion and the second portion B3 from coming into contact with each other and causing an internal short circuit when the beading portion of the battery housing is compressed near the second portion B3.

[0464] The second uncoated portion 43b has the same structure as the first uncoated portion 43a. In one variation, the second uncoated portion 43b may have a conventional electrode structure or an electrode structure of another embodiment (variation).

[0465] The end 91 of the first uncoated portion 43a and the end 91 of the second uncoated portion 43b may be bent in the radial direction of the electrode assembly 90, for example, from the outer periphery toward the core. In this case, the outermost portion 92 of the second portion B3 may not be substantially bent.

[0466] FIG. 13 is a cross-sectional view of a jelly roll-type electrode assembly 100 in which any one of the electrodes 50, 60, and 70 of the third to fifth embodiments (modifications thereof) is used as the first electrode (positive electrode) and the second electrode (negative electrode) along the Y-axis direction (winding axis direction).

[0467] Referring to FIG. 13, the uncoated portion 43a of the first electrode includes a first portion B1 adjacent to the core of the electrode assembly 100, a second portion B3 adjacent to the outer peripheral surface of the electrode assembly 100, and a third portion B2 interposed between the first portion B1 and the second portion B3.

[0468] The height of the first portion B1 is relatively shorter than the height of the third portion B2. The bending length of the innermost uncoated portion 43a in the third portion B2 is equal to or shorter than the radial length R of the first portion B1. The bending length H corresponds to the distance from the point where the uncoated portion 43a is bent to the upper end of the uncoated portion 43a. In a modified example, the bending length H may be smaller than the sum of the radial length R of the first portion B1 and 10% of the radius of the core 102.

[0469] Therefore, even if the third portion B2 is bent, 90% or more of the diameter of the core 102 of the electrode assembly 100 is open to the outside. The core 102 is a cavity in the center of the electrode assembly 100. If the core 102 is not blocked, the electrolyte injection process can be performed without any problems, improving the efficiency of the electrolyte injection. In addition, a welding jig can be inserted through the core 102 to easily perform the welding process between the negative electrode (or positive electrode) side current collector and the battery housing (or terminal).

[0470] The height of the second portion B3 is relatively lower than the height of the third portion B2, which prevents the beading portion of the battery housing from coming into contact with the second portion B3 and causing an internal short circuit when the beading portion is pressurized near the second portion B3.

[0471] In one variation, the height of the second portion B3 may decrease gradually or in steps, unlike the illustration in Figure 13. Also, in Figure 13, the height of the third portion B2 is uniform along a portion of the outer periphery, but the height of the third portion B2 may increase gradually or in steps from the boundary between the first portion B1 and the third portion B2 to the boundary between the third portion B2 and the second portion B3. When the third portion B2 is divided into multiple segments, the section where the height of the uncoated portion 43a changes corresponds to the height-variable section of the segment (section (2) in Figure 10a).

[0472] The second uncoated portion 43b has the same structure as the first uncoated portion 43a. In one variation, the second uncoated portion 43b may have a conventional electrode structure or an electrode structure of another embodiment (variation).

[0473] The end 101 of the first uncoated portion 43a and the end 101 of the second uncoated portion 43b may be bent in the radial direction of the electrode assembly 100, for example, from the outer periphery toward the core. At this time, the first portion B1 and the second portion B3 are not substantially bent.

[0474] When the third portion B2 includes a plurality of segments, bending stress is alleviated, preventing tearing or abnormal deformation of the uncoated portion 43a near the bending point. In addition, when the width and / or height and / or spacing pitch of the segments are adjusted within the ranges of the above-mentioned embodiments, the segments are overlapped to an extent that sufficient welding strength can be ensured when they are bent toward the core, and no open spaces (gaps) are formed in the bent surface area.

[0475] FIG. 14 is a cross-sectional view of an electrode assembly 110 according to yet another embodiment of the present invention, taken along the Y-axis direction (winding axis direction).

[0476] Referring to FIG. 14, the electrode assembly 110 is substantially identical in configuration to the electrode assembly 100 of FIG. 13, except that the height of the second portion B3 is substantially the same as the outermost height of the third portion B2.

[0477] The second portion B3 may include a plurality of segments, the configuration of which is substantially the same as that of the fourth and fifth embodiments (variations) of the electrode.

[0478] In the electrode assembly 110, the height of the first portion B1 is relatively shorter than the height of the third portion B2. The bent length H of the innermost uncoated portion of the third portion B2 is equal to or shorter than the radial length R of the first portion B1. Preferably, the first portion B1 may be a segment-free section (section (1) in FIG. 10a) in which no segment exists. In a variant, the bent length H may be smaller than the sum of the radial length R of the first portion B1 and 10% of the radius of the core 102.

[0479] Therefore, even if the third portion B2 is bent, 90% or more of the diameter of the core 112 of the electrode assembly 110 is open to the outside. If the core 112 is not blocked, the electrolyte injection process can be carried out without any problems, improving the efficiency of the electrolyte injection. In addition, a welding jig can be inserted through the core 112 to easily perform the welding process between the negative electrode (or positive electrode) side current collector and the battery housing (or terminal).

[0480] In one variation, the structure in which the height of the third portion B2 increases gradually or in steps from the core side toward the outer periphery may be extended to the second portion B3. In this case, the height of the uncoated portion 43a may increase gradually or in steps from the boundary between the first portion B1 and the third portion B2 to the outermost surface of the electrode assembly 110.

[0481] The second uncoated portion 43b has the same structure as the first uncoated portion 43a. In one variation, the second uncoated portion 43b may have a conventional electrode structure or an electrode structure of another embodiment (variation).

[0482] The end 111 of the first uncoated portion 43a and the end 111 of the second uncoated portion 43b may be bent in the radial direction of the electrode assembly 110, for example, from the outer periphery toward the core. At this time, the first portion B1 is not substantially bent.

[0483] When the third portion B2 and the second portion B3 include a plurality of segments, bending stress is alleviated, preventing tearing or abnormal deformation of the uncoated portions 43a, 43b near the bending points. Furthermore, when the width and / or height and / or spacing pitch of the segments are adjusted within the ranges of the above-mentioned embodiments, the segments are overlapped to an extent that sufficient welding strength is ensured when they are bent toward the core, and no open spaces (gaps) are formed in the bent surface area.

[0484] FIG. 15 is a cross-sectional view of an electrode assembly 120 according to yet another embodiment of the present invention, taken along the Y-axis direction (winding axis direction).

[0485] 15, the electrode assembly 120 is substantially identical in configuration to the electrode assembly 100 of FIG. 13, except that the height of the third portion B2 gradually or stepwise increases and then decreases. The radius section where the height of the third portion B2 varies may be considered a variable-height section of the segment (section (2) in FIG. 10a). In this case, the variable-height section of the segment may be designed so that a uniform section with a number of layered segments of 10 or more appears in the bending surface region F formed as the third portion B2 is bent, within the desired numerical range described above.

[0486] The change in height of the third portion B2 can be achieved by adjusting the height of the step pattern (see FIG. 6) or the segment (see FIG. 7a or FIG. 8a) included in the third portion B2.

[0487] In the electrode assembly 120, the height of the first portion B1 is relatively shorter than the height of the third portion B2. The bent length H of the innermost uncoated portion of the third portion B2 is equal to or shorter than the radial length R of the first portion B1. The section corresponding to the first portion B1 corresponds to a segment-free section (section (1) in FIG. 10a) where no segment exists. In a modified example, the bent length H may be smaller than the sum of the radial length R of the first portion B1 and 10% of the radius of the core 122.

[0488] Therefore, even if the third portion B2 is bent toward the core side, the core 122 of the electrode assembly 120 is open to the outside by 90% or more of its diameter. If the core 122 is not blocked, the electrolyte injection process can be performed without any problems, improving the efficiency of the electrolyte injection. In addition, a welding jig can be inserted through the core 122 to easily perform the welding process between the negative (or positive) electrode current collector and the battery housing (or terminal).

[0489] The height of the second portion B3 is relatively lower than the height of the third portion B2, and preferably the second portion B3 does not need to have a dividing piece formed therein. This prevents the beading portion of the battery housing from coming into contact with the second portion B3 and causing an internal short circuit when the beading portion is pressurized near the second portion B3. In one variation, the height of the second portion B3 may decrease gradually or in stages toward the outer periphery.

[0490] The second uncoated portion 43b has the same structure as the first uncoated portion 43a. In a modified example, the second uncoated portion 43b may have a conventional electrode structure or an electrode structure of another embodiment (modified example).

[0491] The end 121 of the first uncoated portion 43a and the end 121 of the second uncoated portion 43b may be bent from the outer periphery toward the core of the electrode assembly 120. At this time, the first portion B1 and the second portion B3 are not substantially bent.

[0492] When the third portion B2 includes a plurality of segments, bending stress is alleviated, preventing tearing or abnormal deformation of the uncoated portions 43a, 43b. In addition, when the width and / or height and / or spacing pitch of the segments are adjusted within the ranges of the above-described embodiments, the segments are folded toward the core, overlapping each other to an extent that sufficient welding strength is ensured, and no open spaces (gaps) are formed in the folded surface area.

[0493] FIG. 16 is a cross-sectional view of an electrode assembly 130 according to yet another embodiment of the present invention, taken along the Y-axis direction (winding axis direction).

[0494] Referring to FIG. 16, the electrode assembly 130 has the following advantages compared to the electrode assembly 120 of FIG. The height of the second portion B3 is from the boundary between the second portion B3 and the third portion B2 to the top of the electrode assembly 130. Other configurations except that the pattern has a gradual or stepwise decrease toward the outer surface. are substantially identical.

[0495] The height change of the second portion B3 can be realized by extending the step pattern (see FIG. 6) included in the third portion B2 to the second portion B3 while gradually or stepwise decreasing the height of the pattern toward the outer periphery. In another modification, the height change of the second portion B3 can be realized by extending the segment structure of the third portion B2 to the second portion B3 while gradually or stepwise decreasing the height of the segment toward the outer periphery.

[0496] In the electrode assembly 130, the height of the first portion B1 is relatively shorter than the height of the third portion B2. The bent length H of the innermost uncoated portion of the third portion B2 is equal to or shorter than the radial length R of the first portion B1. The first portion B1 corresponds to a segment-free section (section (1) in FIG. 10a) where no segment exists. In a modified example, the bent length H may be smaller than the sum of the radial length R of the first portion B1 and 10% of the radius of the core 132.

[0497] Therefore, even if the third portion B2 is bent toward the core side, 90% or more of the diameter of the core 132 of the electrode assembly 130 is open to the outside. If the core 132 is not blocked, the electrolyte injection process can be performed without any problems, improving the efficiency of the electrolyte injection. In addition, a welding jig can be inserted through the core 132 to easily perform the welding process between the negative (or positive) electrode current collector and the battery housing (or terminal).

[0498] The second uncoated portion 43b has the same structure as the first uncoated portion 43a. In one variation, the second uncoated portion 43b may have a conventional electrode structure or an electrode structure of another embodiment (variation).

[0499] The end 131 of the first uncoated portion 43a and the end 131 of the second uncoated portion 43b may be bent from the outer periphery toward the core of the electrode assembly 130. At this time, the first portion B1 is not substantially bent.

[0500] When the third portion B2 and the second portion B3 include a plurality of segments, bending stress is alleviated, preventing tearing or abnormal deformation of the uncoated portions 43a, 43b near the bending points. Furthermore, when the width and / or height and / or spacing pitch of the segments are adjusted within the ranges of the above-mentioned embodiments, the segments are overlapped to an extent that sufficient welding strength is ensured when they are bent toward the core, and no open spaces (gaps) are formed in the bent surface area.

[0501] Meanwhile, in the above-described embodiment (variant), the ends of the first uncoated region 43a and the second uncoated region 43b may be bent from the core side toward the outer periphery. In this case, the second portion B3 is preferably designed as a segment-free section (section (1) in FIG. 10a) without any segment, and is not bent toward the outer periphery. The radial width of the second portion B3 may be equal to or greater than the length of the bent outermost uncoated region (or segment) of the third portion B2. Therefore, when the outermost uncoated region (or segment) of the third portion B2 is bent toward the outer periphery, the end of the bent portion does not protrude beyond the outer periphery of the electrode assembly toward the inner surface of the battery housing. The change pattern of the segment structure may be opposite to that of the above-described embodiment (variant). For example, the height of the segment may increase stepwise or gradually from the core side toward the outer periphery. That is, by sequentially arranging a section where segment pieces are omitted (section (1) in Figure 10a), a section where segment piece height is variable (section (2) in Figure 10a), and a section where segment piece height is uniform (section (3) in Figure 10a) from the outer periphery side of the electrode assembly toward the core side, a uniform number of segment piece stacks section, where the number of segment piece stacks is 10 or more, may appear in a desired numerical range in the folded surface region.

[0502] Various electrode assembly structures according to embodiments of the present invention can be applied to cylindrical batteries.

[0503] Desirably, the cylindrical battery may have a form factor ratio (defined as the diameter divided by the height of the cylindrical battery, i.e., the ratio of height (H) to diameter (Φ)) of greater than about 0.4, where form factor refers to the diameter and height of the cylindrical battery.

[0504] Preferably, the diameter of the cylindrical battery may be 40mm to 50mm, and the height may be 60mm to 130mm. The form factor of the cylindrical battery according to one embodiment may be, for example, 46110, 4875, 48110, 4880, or 4680. In the number indicating the form factor, the first two digits indicate the diameter of the battery, and the remaining digits indicate the height of the battery.

[0505] When an electrode assembly having a tabless structure is applied to a cylindrical battery with a form factor ratio exceeding 0.4, the uncoated portion is easily torn due to the large radial stress applied when the uncoated portion is bent. Furthermore, when welding a current collector to the bent surface area of the uncoated portion, the number of layers of the uncoated portion in the bent surface area must be increased to ensure sufficient welding strength and reduce resistance. These requirements can be met by the electrode and electrode assembly according to an embodiment (variant) of the present invention.

[0506] A battery according to one embodiment of the present invention may be a cylindrical battery having a substantially cylindrical shape with a diameter of about 46 mm, a height of about 110 mm, and a form factor ratio of 0.418.

[0507] Another example battery may be a cylindrical battery having a generally cylindrical shape with a diameter of about 48 mm, a height of about 75 mm, and a form factor ratio of 0.640.

[0508] In yet another embodiment, the battery may be a generally cylindrical battery having a diameter of about 48 mm, a height of about 110 mm, and a form factor ratio of 0.436.

[0509] In yet another embodiment, the battery may be a generally cylindrical battery having a diameter of about 48 mm, a height of about 80 mm, and a form factor ratio of 0.600.

[0510] In yet another embodiment, the battery may be a generally cylindrical battery having a diameter of about 46 mm, a height of about 80 mm, and a form factor ratio of 0.575.

[0511] Conventionally, batteries with a form factor ratio of approximately 0.4 or less have been used. For example, 1865 batteries and 2170 batteries have been used. 1865 batteries have a diameter of approximately 18 mm and a height of approximately 65 mm, resulting in a form factor ratio of 0.277. 2170 batteries have a diameter of approximately 21 mm and a height of approximately 70 mm, resulting in a form factor ratio of 0.300.

[0512] Hereinafter, a cylindrical battery according to an embodiment of the present invention will be described in detail.

[0513] FIG. 17 is a cross-sectional view of a cylindrical battery 140 according to an embodiment of the present invention taken along the Y-axis direction.

[0514] Referring to FIG. 17, a cylindrical battery 140 according to one embodiment of the present invention includes an electrode assembly 141 including a first electrode, a separator, and a second electrode, a battery housing 142 that houses the electrode assembly 141, and a seal 143 that seals the open end of the battery housing 142.

[0515] The battery housing 142 is a cylindrical container with an opening at the top. The battery housing 142 is made of a conductive metal material such as aluminum, steel, or stainless steel. A nickel coating layer may be formed on the surface of the battery housing 142. The battery housing 142 accommodates the electrode assembly 141 in the inner space through the opening at the top, along with the electrolyte.

[0516] The electrolyte is A + B - where A + Li + , Na + , K. + or a combination thereof. - is F - , Cl - , Br - , I - , NO3 - , N(CN)2 - , BF4 - , ClO4 - , AlO4 - , AlCl4 - , PF6 - , SbF6 - , AsF6 - , BF2C2O4 - , BC4O8 - , (CF3)2PF4 - , (CF3)3PF3 - , (CF3)4PF2 - , (CF3)5PF - , (CF3)6P - , CF3SO3 - , C4F9SO3 - , CF3CF2SO3 - , (CF3SO2)2N - , (FSO2)2N - , CF3CF2(CF3)2CO - , (CF3SO2)2CH - , (SF5)3C - , (CF3SO2)3C - , CF3(CF2)7SO3, CF3CO2 - , CH3CO2- , SCN - and (CF3CF2SO2)2N - The anion comprises one or more anions selected from the group consisting of:

[0517] The electrolyte may be dissolved in an organic solvent such as propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, tetrahydrofuran, N-methyl-2-pyrrolidone (NMP), ethyl methyl carbonate (EMC), γ-butyrolactone, or a mixture thereof.

[0518] The electrode assembly 141 may have a jelly-roll structure, but the present invention is not limited thereto. The electrode assembly 141 may be manufactured by sequentially stacking a lower separator, a first electrode, an upper separator, and a second electrode at least once, and winding the stack around a winding shaft C, as shown in FIG.

[0519] The first electrode and the second electrode have opposite polarities. That is, if one has a positive polarity, the other has a negative polarity. At least one of the first electrode and the second electrode may have an electrode structure according to the above-described embodiment (variant). Furthermore, the other of the first electrode and the second electrode may have a conventional electrode structure or an electrode structure according to the embodiment (variant). The number of electrode pairs included in the electrode assembly 141 is not limited to one, but may be two or more.

[0520] A first uncoated portion 146a of the first electrode and a second uncoated portion 146b of the second electrode protrude from the top and bottom of the electrode assembly 141, respectively. The first electrode has the electrode structure of the first embodiment (variant). Therefore, in the first uncoated portion 146a, the height of the second portion B3 is lower than the height of the uncoated portions of other portions. The second portion B3 is spaced a predetermined distance from the inner circumferential surface of the battery housing 142, particularly the beading portion 147. Therefore, the second portion B3 of the first electrode does not contact the battery housing 142, which is electrically connected to the second electrode, preventing an internal short circuit of the cylindrical battery 140.

[0521] The second uncoated portion 146b of the second electrode may have the same structure as the first uncoated portion 146a. In another modification, the second uncoated portion 146b may selectively have the structure of the uncoated portion of the electrode according to the embodiment (modification).

[0522] The sealing body 143 may include a plate-shaped cap 143a, a first gasket 143b having insulating properties and providing airtightness between the cap 143a and the battery housing 142, and a connecting plate 143c electrically and mechanically connected to the cap 143a.

[0523] The cap 143a is a component made of a conductive metal material and covers the upper opening of the battery housing 142. The cap 143a is electrically connected to the first uncoated portion 146a of the first electrode and is electrically insulated from the battery housing 142 via the first gasket 143b. Therefore, the cap 143a can function as a first electrode terminal (e.g., a positive electrode) of the cylindrical battery 140.

[0524] The cap 143a is placed on a beading portion 147 formed on the battery housing 142 and fixed by a crimping portion 148. A first gasket 143b may be interposed between the cap 143a and the crimping portion 148 to ensure airtightness of the battery housing 142 and to provide electrical insulation between the battery housing 142 and the cap 143a. The cap 143a may have a protrusion 143d formed to protrude upward from the center thereof.

[0525] The battery housing 142 is electrically connected to the second uncoated portion 146b of the second electrode. Therefore, the battery housing 142 has the same polarity as the second electrode. If the second electrode has a negative polarity, the battery housing 142 also has a negative polarity.

[0526] The battery housing 142 has a beading portion 147 and a crimping portion 148 at its upper end. The beading portion 147 is formed by pressing in around the outer periphery of the battery housing 142. The beading portion 147 prevents the electrode assembly 141 housed inside the battery housing 142 from slipping out of the upper opening of the battery housing 142, and can also function as a support portion on which the sealing body 143 is placed.

[0527] The inner circumferential surface of the beading portion 147 is spaced a predetermined distance from the second portion B3 of the first electrode. More specifically, the lower end of the inner circumferential surface of the beading portion 147 is spaced a predetermined distance from the second portion B3 of the first electrode. In addition, because the second portion B3 has a low height, it is not substantially affected when the battery housing 142 is pressed from the outside to form the beading portion 147. Therefore, the second portion B3 is not compressed by other components such as the beading portion 147, which prevents partial deformation of the electrode assembly 141 and prevents internal short circuits in the cylindrical battery 140.

[0528] Preferably, the relationship D1≦D2 is satisfied, where D1 is the pressing depth of the beading portion 147 and D2 is the radial length from the inner circumferential surface of the battery housing 142 to the boundary between the second portion B3 and the third portion B2. In this case, damage to the second portion B3 is substantially prevented when the battery housing 142 is pressed to form the beading portion 147.

[0529] The crimping portion 148 is formed on the upper portion of the beading portion 147. The crimping portion 148 is extended and bent to enclose the outer circumferential surface of the cap 143a disposed on the beading portion 147 and a part of the upper surface of the cap 143a.

[0530] The cylindrical battery 140 may further include a first current collector 144 and / or a second current collector 145 and / or an insulator 146 .

[0531] The first current collector 144 is coupled to the upper part of the electrode assembly 141. The first current collector 144 is made of a conductive metal material such as aluminum, copper, steel, or nickel, and is electrically connected to the first uncoated portion 146a of the first electrode. The electrical connection may be made by welding. A lead 149 may be connected to the first current collector 144. The lead 149 may extend above the electrode assembly 141 and be coupled to the connecting plate 143c, or may be directly coupled to the lower surface of the cap 143a. The lead 149 may be coupled to other components by welding.

[0532] Preferably, the first current collector 144 may be integrally formed with the lead 149. In this case, the lead 149 may have a long plate shape extending outward from near the center of the first current collector 144.

[0533] The first current collector 144 may have a plurality of radially formed concaves and convexes (not shown) on its lower surface. When the radial concaves and convexes are provided, the first current collector 144 may be pressed against the concaves and convexes to press the first uncoated portion 146a of the first electrode into the concaves and convexes.

[0534] The first current collector 144 is bonded to an end of the first uncoated portion 146a. The first uncoated portion 146a and the first current collector 144 may be bonded together by, for example, laser welding. Laser welding may be performed by partially melting the base material of the first current collector 144. In a modified example, the first current collector 144 and the first uncoated portion 146a may be welded together using solder. In this case, the solder may have a lower melting point than the first current collector 144 and the first uncoated portion 146a. Laser welding may be replaced by resistance welding, ultrasonic welding, spot welding, etc.

[0535] A second current collector 145 may be coupled to the bottom surface of the electrode assembly 141. One surface of the second current collector 145 may be coupled to the second uncoated portion 146b by welding, and the other surface may be coupled to the inner bottom surface of the battery housing 142 by welding. The coupling structure between the second current collector 145 and the second uncoated portion 146b may be substantially the same as the coupling structure between the first current collector 144 and the first uncoated portion 146a.

[0536] The uncoated portions 146a and 146b are not limited to the structure shown in the drawings. Therefore, the uncoated portions 146a and 146b may selectively have the structure of the uncoated portions of the electrodes according to the embodiment (variant) as well as the structure of the conventional uncoated portions.

[0537] The insulator 146 can cover the first current collector 144. By covering the first current collector 144 on the upper surface of the first current collector 144, the insulator 146 can prevent direct contact between the first current collector 144 and the inner circumferential surface of the battery housing 142.

[0538] The insulator 146 has a lead hole 151 through which the lead 149 extending upward from the first current collector 144 is drawn out. The lead 149 is drawn out upward through the lead hole 151 and coupled to the lower surface of the connection plate 143c or the lower surface of the cap 143a.

[0539] The peripheral region of the insulator 146 may be interposed between the first current collector 144 and the beading portion 147 to fix the combination of the electrode assembly 141 and the first current collector 144. This limits movement of the combination of the electrode assembly 141 and the first current collector 144 in the winding axis direction (Y-axis direction) of the cylindrical battery 140, thereby improving the assembly stability of the cylindrical battery 140.

[0540] The insulator 146 may be made of an insulating polymer resin. As an example, the insulator 146 may be made of polyethylene, polypropylene, polyimide, or polybutylene terephthalate.

[0541] The battery housing 142 may further include a venting portion 152 formed on its bottom surface. The venting portion 152 corresponds to a region on the bottom surface of the battery housing 142 that is thinner than the surrounding region. The venting portion 152 is structurally weaker than the surrounding region. Therefore, if an abnormality occurs in the cylindrical battery 140 and the internal pressure increases above a certain level, the venting portion 152 may burst, allowing the gas generated inside the battery housing 142 to be released to the outside. The internal pressure at which the venting portion 152 bursts is approximately 15 kgf / cm. 2 ~35kgf / cm 2 It could be.

[0542] The vents 152 may be formed continuously or discontinuously in a circular pattern on the underside of the battery housing 142. Alternatively, the vents 152 may be formed in a linear pattern or other patterns.

[0543] FIG. 18 is a cross-sectional view of a cylindrical battery 150 according to another embodiment of the present invention, taken along the Y-axis direction.

[0544] Referring to FIG. 18, the cylindrical battery 150 is substantially identical in configuration to the cylindrical battery 140 of FIG. 17 except that the electrode structure of the second embodiment (variant) is adopted for the first uncoated portion 146a of the first electrode.

[0545] 18, the first uncoated portion 146a of the first electrode may have a shape in which the height of the second portion B3 gradually or stepwise decreases toward the inner circumferential surface of the battery housing 142. Preferably, an imaginary line connecting the uppermost ends of the second portion B3 may have the same or similar shape as the inner circumferential surface of the beading portion 147.

[0546] The second portion B3 forms an inclined surface. Therefore, when the battery housing 142 is pressed to form the beading portion 147, the second portion B3 is prevented from being compressed and damaged by the beading portion 147. In addition, the second portion B3 is prevented from coming into contact with the battery housing 142 of the opposite polarity, which may cause an internal short circuit.

[0547] Other configurations of the cylindrical battery 150 are substantially the same as those of the above-described embodiment (modification).

[0548] The uncoated portions 146a and 146b are not limited to the structure shown in the drawings. Therefore, the uncoated portions 146a and 146b may selectively have the structure of the uncoated portions of the electrodes according to the embodiment (variant) as well as the structure of the conventional uncoated portions.

[0549] FIG. 19 is a cross-sectional view of a cylindrical battery 160 according to yet another embodiment of the present invention, taken along the Y-axis direction.

[0550] Referring to FIG. 19, the cylindrical battery 160 is substantially identical in configuration to the cylindrical batteries 140 and 150 described above, except that the lead 149 connected to the first current collector 144 is directly connected to the cap 143a of the sealing body 143 through the lead hole 151 of the insulator 146, and the insulator 146 and the first current collector 144 are closely attached to the underside of the cap 143a.

[0551] In the cylindrical battery 160, the diameter of the first current collector 144 and the outermost diameter of the third portion B2 are smaller than the smallest inner diameter of the battery housing 142. Also, the diameter of the first current collector 144 can be the same as or larger than the outermost diameter of the third portion B2.

[0552] Specifically, the minimum inner diameter of the battery housing 142 may correspond to the inner diameter of the battery housing 142 at the position where the beading portion 147 is formed. In this case, the outermost diameters of the first current collector 144 and the third portion B2 are smaller than the inner diameter of the battery housing 142 at the position where the beading portion 147 is formed. In addition, the diameter of the first current collector 144 may be the same as or larger than the outermost diameter of the third portion B2. The peripheral region of the insulator 146 may be bent downward and interposed between the second portion B3 and the beading portion 147, thereby fixing the combination of the electrode assembly 141 and the first current collector 144.

[0553] Preferably, the insulator 146 includes a portion covering the second portion B3 and a portion covering the first current collector 144, and the portion connecting these two portions may be curved together to correspond to the curved shape of the beading portion 147. The insulator 146 may insulate the second portion B3 from the inner circumferential surface of the beading portion 147, and may also insulate the first current collector 144 from the inner circumferential surface of the beading portion 147.

[0554] The first current collector 144 may be positioned higher than the lower end of the beading portion 147 and may be coupled to the first portion B1 and the third portion B2. In this case, the pressing depth D1 of the beading portion 147 is equal to or smaller than the distance D2 from the inner circumferential surface of the battery housing 142 to the boundary between the second portion B3 and the third portion B2. Therefore, the first portion B1 and the third portion B2 and the first current collector 144 coupled thereto may be positioned higher than the lower end of the beading portion 147. The lower end of the beading portion 147 refers to the bending point B between the beading portion 147 and the portion of the battery housing 142 that houses the electrode assembly 141.

[0555] Because the first portion B1 and the third portion B2 occupy the radially inner space of the beading portion 147, the empty space between the electrode assembly 141 and the cap 143a is minimized. In addition, the connecting plate 143c, which was located in the empty space between the electrode assembly 141 and the cap 143a, is omitted. Therefore, the lead 149 of the first current collector 144 can be directly connected to the bottom surface of the cap 143a. This structure reduces the empty space within the battery, allowing the energy density to be maximized by the reduced empty space.

[0556] In the cylindrical battery 160, the first current collector 144 and the second current collector 145 may be welded to the ends of the first uncoated portion 146a and the second uncoated portion 146b, respectively, similar to the above-described embodiments.

[0557] The uncoated portions 146a and 146b are not limited to the structure shown in the drawings. Therefore, the uncoated portions 146a and 146b may selectively have the structure of the uncoated portions of the electrodes according to the embodiment (variant) as well as the structure of the conventional uncoated portions.

[0558] FIG. 20 is a cross-sectional view of a cylindrical battery 170 according to yet another embodiment of the present invention, taken along the Y-axis direction.

[0559] Referring to FIG. 20, the cylindrical battery 170 differs from the cylindrical battery 140 shown in FIG. 17 in that the structure of the electrode assembly is substantially the same, but other structures except for the electrode assembly have been changed.

[0560] Specifically, the cylindrical battery 170 includes a battery housing 171 through which a terminal 172 is inserted. The terminal 172 is attached through a through-hole formed on the closed surface (top surface in the drawing) of the battery housing 171. The terminal 172 is riveted into the through-hole of the battery housing 171 with a second gasket 173 made of an insulating material interposed therebetween. The terminal 172 is exposed to the outside in the direction opposite to the direction of gravity.

[0561] The terminal 172 includes a terminal exposing portion 172a and a terminal inserting portion 172b. The terminal exposing portion 172a is exposed to the outside of the closed surface of the battery housing 171. The terminal exposing portion 172a may be located approximately at the center of the closed surface of the battery housing 171. The maximum diameter of the terminal exposing portion 172a may be larger than the maximum diameter of the through-hole formed in the battery housing 171. The terminal inserting portion 172b may penetrate approximately the center of the closed surface of the battery housing 171 to be electrically connected to the first uncoated portion 146a of the first electrode. The bottom edge of the terminal inserting portion 172b may be rivet-connected to the inner surface of the battery housing 171. That is, the bottom edge of the terminal inserting portion 172b may be bent toward the inner surface of the battery housing 171. A flat portion 172c may be included on the inside of the bottom edge of the terminal inserting portion 172b. The maximum diameter of the bottom of the riveted terminal insertion portion 172b may be even larger than the maximum diameter of the through hole of the battery housing 171.

[0562] The flat portion 172c of the terminal insertion portion 172b may be welded to the center of the first current collector 144 connected to the first uncoated portion 146a of the first electrode. Laser welding is a preferred welding method, but other welding methods such as ultrasonic welding may be used instead.

[0563] An insulator 174 made of an insulating material may be interposed between the first current collector 144 and the inner surface of the battery housing 171. The insulator 174 covers the upper portion of the first current collector 144 and the upper peripheral edge portion of the electrode assembly 141. This prevents the second portion B3 of the electrode assembly 141 from coming into contact with the inner surface of the battery housing 171, which has the opposite polarity, and causing a short circuit.

[0564] The thickness of the insulator 174 corresponds to or is slightly larger than the distance between the top surface of the first current collector 144 and the inner surface of the closed portion of the battery housing 171. Thus, the insulator 174 can contact the top surface of the first current collector 144 and the inner surface of the closed portion of the battery housing 171.

[0565] The terminal insertion portion 172b of the terminal 172 may be welded to the first current collector 144 through a through hole in the insulator 174. The diameter of the through hole formed in the insulator 174 may be larger than the diameter of the riveting portion at the bottom of the terminal insertion portion 172b. Desirably, the through hole may expose the bottom of the terminal insertion portion 172b and the second gasket 173.

[0566] The second gasket 173 is interposed between the battery housing 171 and the terminal 172 to prevent electrical contact between the battery housing 171 and the terminal 172, which have opposite polarities. This allows the upper surface of the battery housing 171, which has a substantially flat shape, to function as a second electrode terminal (e.g., a negative electrode) of the cylindrical battery 170.

[0567] The second gasket 173 includes a gasket exposing portion 173a and a gasket inserting portion 173b. The gasket exposing portion 173a is interposed between the terminal exposing portion 172a of the terminal 172 and the battery housing 171. The gasket inserting portion 173b is interposed between the terminal inserting portion 172b of the terminal 172 and the battery housing 171. The gasket inserting portion 173b may be deformed when the terminal inserting portion 172b is riveted, thereby adhering closely to the inner surface of the battery housing 171. The second gasket 173 may be made of, for example, an insulating polymer resin.

[0568] The gasket exposing portion 173a of the second gasket 173 may extend to cover the outer peripheral surface of the terminal exposing portion 172a of the terminal 172. When the second gasket 173 covers the outer peripheral surface of the terminal 172, it is possible to prevent a short circuit from occurring during the process of connecting an electrical connection component, such as a bus bar, to the upper surface of the battery housing 171 and / or the terminal 172. Although not shown, the gasket exposing portion 173a may extend to cover not only the outer peripheral surface of the terminal exposing portion 172a but also a portion of the upper surface.

[0569] When second gasket 173 is made of a polymer resin, second gasket 173 can be joined to battery housing 171 and terminal 172 by heat sealing. In this case, the airtightness at the joining interface between second gasket 173 and terminal 172 and at the joining interface between second gasket 173 and battery housing 171 is strengthened. On the other hand, when gasket exposed portion 173a of second gasket 173 extends to the upper surface of terminal exposed portion 172a, terminal 172 may be joined integrally with second gasket 173 by insert injection molding.

[0570] The remaining area 175 on the top surface of the battery housing 171 excluding the area occupied by the terminal 172 and the second gasket 173 corresponds to a second electrode terminal having a polarity opposite to that of the terminal 172 .

[0571] The second current collector 176 is coupled to the lower part of the electrode assembly 141. The second current collector 176 is made of a conductive metal material such as aluminum, steel, copper, or nickel, and is electrically connected to the second uncoated portion 146b of the second electrode.

[0572] Preferably, the second current collector 176 is electrically connected to the battery housing 171. Therefore, the second current collector 176 may be fixed with at least a portion of its periphery interposed between the inner surface of the battery housing 171 and the first gasket 178b. As an example, at least a portion of the periphery of the second current collector 176 may be fixed to the beading portion 180 by welding while being supported on the lower end surface of the beading portion 180 formed at the lower end of the battery housing 171. In a modified example, at least a portion of the periphery of the second current collector 176 may be directly welded to the inner wall surface of the battery housing 171.

[0573] The second current collector 176 may have a plurality of projections and recesses (not shown) formed radially on the surface facing the second uncoated portion 146b. When the projections and recesses are formed, the second current collector 176 may be pressed against the second uncoated portion 146b to press the projections and recesses into the projections and recesses.

[0574] Preferably, the second current collector 176 and the end of the second uncoated portion 146b may be joined by welding, for example, laser welding. In addition, the welded portion between the second current collector 176 and the second uncoated portion 146b may be spaced a predetermined distance from the inner circumferential surface of the beading portion 180 toward the core C.

[0575] The sealing body 178, which seals the lower open end of the battery housing 171, includes a plate-shaped cap 178a and a first gasket 178b. The first gasket 178b electrically isolates the cap 178a from the battery housing 171. The crimping portion 181 secures the periphery of the cap 178a to the first gasket 178b. The cap 178a is provided with a vent portion 179. The configuration of the vent portion 179 is substantially the same as in the above-described embodiment (variant). The lower surface of the cap 178a may be located higher than the lower end of the crimping portion 181. In this case, a space is formed below the cap 178a, allowing for smooth venting. This is particularly useful when the cylindrical battery 170 is installed with the crimping portion 181 facing the direction of gravity.

[0576] Preferably, the cap 178a is made of a conductive metal material. However, since the first gasket 178b is interposed between the cap 178a and the battery housing 171, the cap 178a does not have electrical polarity. The sealing body 178 seals the open end of the lower part of the battery housing 171 and mainly functions to release gas when the internal pressure of the battery 170 exceeds a critical value. The critical value of the internal pressure is 15 kgf / cm. 2 ~35kgf / cm 2 is.

[0577] Preferably, the terminal 172 electrically connected to the first uncoated portion 146a of the first electrode is used as the first electrode terminal. Furthermore, a portion 175 of the upper surface of the battery housing 171, excluding the terminal 172, electrically connected to the second uncoated portion 146b of the second electrode via the second current collector 176 is used as the second electrode terminal, which has the opposite polarity to the first electrode terminal. When two electrode terminals are located on the upper portion of the cylindrical battery 170, electrical connection components such as bus bars can be disposed on only one side of the cylindrical battery 170. This simplifies the battery pack structure and improves energy density. Furthermore, the portion 175 used as the second electrode terminal has a substantially flat shape, ensuring a sufficient connection area for connecting electrical connection components such as bus bars. This allows the cylindrical battery 170 to reduce resistance at the connection points of electrical connection components to a desired level.

[0578] Meanwhile, the structure of the electrode assembly 141 and the structure of the uncoated portion are not limited to those shown in the drawings, and may be replaced with the structures of the above-described embodiment (variations).

[0579] FIG. 21 is a cross-sectional view of a cylindrical battery 180 according to yet another embodiment of the present invention, taken along the Y-axis direction.

[0580] Referring to FIG. 21, the structure of the electrode assembly 141 of the cylindrical battery 180 is substantially the same as that of the cylindrical battery 150 shown in FIG. 18, and other configurations except for the electrode assembly 141 are substantially the same as that of the cylindrical battery 170 shown in FIG. 20.

[0581] Therefore, the configurations of the embodiments (variations) of the cylindrical batteries 150 and 170 can be similarly applied to the cylindrical battery 180.

[0582] Furthermore, the structure of the electrode assembly 141 and the structure of the uncoated portion are not limited to those shown in the drawings, and may be replaced with the structures of the above-described embodiments (variations).

[0583] FIG. 22 is a cross-sectional view of a cylindrical battery 190 according to yet another embodiment of the present invention, taken along the Y-axis direction.

[0584] 22, a cylindrical battery 190 includes the electrode assembly 110 shown in FIG. 14, and other configurations except for the electrode assembly 110 are substantially identical to the cylindrical battery 140 shown in FIG. 17. Therefore, the configurations described with reference to FIGS. 14 and 17 can be applied substantially in the same manner to this embodiment.

[0585] 10a and 22, the first uncoated portion 146a and the second uncoated portion 146b of the electrode assembly 110 are bent in the radial direction of the electrode assembly 110, for example, from the outer periphery to the core, to form a bent surface region F.

[0586] The first portion B1 is shorter than the other portions and corresponds to the segment omission section a1 where no segment exists, and therefore cannot be bent toward the core side.

[0587] Preferably, the folded surface region F may include, from the core side to the outer periphery, a segment-free section a1, a segment-height variable section a2, and a segment-height uniform section a3.

[0588] As shown in FIGS. 10c, 10d, and 10e, the folded surface region F includes a section a1 where no segment is present and a section b1 where the number of stacked segments is uniform and where the number of stacked segments is 10 or more.

[0589] The folded surface region F may also include a layer number decreasing section b2 adjacent to the outer periphery of the electrode assembly 110, where the number of layers of the segment decreases toward the outer periphery. Preferably, the layer number uniform section b1 may be set as a welding target region.

[0590] In the folded surface region F, the desirable numerical ranges for the ratio (a2 / c) of the height variable section a2 to the radius region (c) including the segment, the ratio (b1 / c) of the uniform number of layers section b1 to the radius region (c) including the segment, and the ratio of the area of the uniform number of layers section b1 to the area of the folded surface region F have been described above, so repeated explanations will be omitted.

[0591] The first current collector 144 may be laser welded to the bent surface region F of the first uncoated portion 146a, and the second current collector 145 may be laser welded to the bent surface region F of the second uncoated portion 146b. The welding method may be ultrasonic welding, resistance welding, spot welding, or the like.

[0592] Preferably, 50% or more of the welding region W of the first current collector 144 and the second current collector 145 may overlap with the uniform lamination number section b1 of the folded surface region F. Optionally, the remaining region of the welding region W may overlap with the reduced lamination number section b2 of the folded surface region F. It is more preferable that the entire welding region W overlaps with the uniform lamination number section b1 in terms of high welding strength, low resistance at the welding interface, and prevention of damage to the separator and active material layer.

[0593] Preferably, the number of layers of the divided pieces may be 10 to 35 in the uniform layer number section b1 overlapping the welding area W and optionally in the reduced layer number section b2.

[0594] Alternatively, if the number of layers in the divided section of the layer count reduction section b2 overlapping the welding area W is less than 10, the laser power for welding the layer count reduction section b2 can be lower than the laser power for welding the uniform layer count section b1. That is, if the welding area W overlaps the uniform layer count section b1 and the layer count reduction section b2 at the same time, the laser power can be changed depending on the number of layers in the divided section. In this case, the weld strength of the uniform layer count section b1 can be greater than the weld strength of the layer count reduction section b2.

[0595] In the folded surface region F formed on the upper and lower parts of the electrode assembly 110, the radial lengths of the segment-omitted section a1 and / or the segment-height variable section a2 and / or the segment-height uniform section a3 may be the same or different.

[0596] The height of the first portion B1 of the electrode assembly 110 is relatively lower than the other portions. Also, as shown in Fig. 14, the bending length H of the innermost uncoated portion of the third portion B2 is smaller than the sum of the radial length R of the first portion B1 and 10% of the radius of the core 112.

[0597] Therefore, even if the first uncoated portion 146a is bent toward the core, 90% or more of the diameter of the core 112 of the electrode assembly 110 can be exposed to the outside. If the core 112 is not blocked, the electrolyte injection process can be performed without any problems, improving the efficiency of the electrolyte injection. In addition, a welding jig can be inserted through the core 112 to easily perform the welding process between the second current collector 145 and the battery housing 142.

[0598] When the plain portions 146a, 146b have a divided structure, if the width and / or height and / or spacing pitch of the divided pieces are adjusted to satisfy the numerical range of the above-mentioned embodiment, when the divided pieces are bent, the divided pieces overlap each other to an extent that sufficient welding strength can be ensured, and no open space (gap) is formed in the folded surface area F.

[0599] Preferably, the first current collector 144 and the second current collector 145 may have an outer diameter that covers the ends of the folded segments (see 61 and 61' in FIG. 10f) at the final winding turn of the uniform-height section a3 of the first and second electrodes. In this case, the folded segments forming the folded surface area F can be welded while being uniformly pressed by the current collectors, and the tightly stacked state of the segments can be maintained even after welding. A tightly stacked state means that there are substantially no gaps between the segments, as shown in FIG. 10a. The tightly stacked state contributes to reducing the resistance of the cylindrical battery 190 to a level suitable for fast charging (e.g., 4 mΩ) or less.

[0600] The structure of the uncoated portions 146a and 146b may be modified to the structure according to the above-described embodiment (variation), and there is no restriction that the conventional uncoated portion structure may be applied to either one of the uncoated portions 146a and 146b.

[0601] FIG. 23 is a cross-sectional view of a cylindrical battery 200 according to yet another embodiment of the present invention, taken along the Y-axis direction.

[0602] 23, a cylindrical battery 200 includes the electrode assembly 110 shown in FIG. 14, and other configurations except for the electrode assembly 110 are substantially the same as the cylindrical battery 180 shown in FIG. 21. Therefore, the configurations described with reference to FIGS. 14 and 21 can be applied substantially in the same manner to this embodiment.

[0603] 10a and 23, the first uncoated portion 146a and the second uncoated portion 146b of the electrode assembly 110 are bent in the radial direction of the electrode assembly 110, for example, from the outer periphery to the core, to form a bent surface region F.

[0604] The first portion B1 is shorter than the other portions and corresponds to the segment omission section a1 where no segment exists, and therefore cannot be bent toward the core side.

[0605] Preferably, the folded surface region F may include, from the core side to the outer periphery, a segment-free section a1, a segment-height variable section a2, and a segment-height uniform section a3.

[0606] As shown in FIGS. 10c, 10d, and 10e, the folded surface region F includes a section a1 where no segment is present and a section b1 where the number of stacked segments is uniform and where the number of stacked segments is 10 or more.

[0607] The folded surface region F may also include a layer number decreasing section b2 adjacent to the outer periphery of the electrode assembly 110, where the number of layers of the segment decreases toward the outer periphery. Preferably, the layer number uniform section b1 may be set as a welding target region.

[0608] In the folded surface region F, the desirable numerical ranges for the ratio (a2 / c) of the height variable section a2 to the radius region (c) including the segment, the ratio (b1 / c) of the uniform number of layers section b1 to the radius region (c) including the segment, and the ratio of the area of the uniform number of layers section b1 to the area of the folded surface region F have been described above, so repeated explanations will be omitted.

[0609] The first current collector 144 may be laser welded to the folded surface region F of the first uncoated portion 146a, and the second current collector 176 may be laser welded to the folded surface region F of the second uncoated portion 146b. The welding method may be ultrasonic welding, resistance welding, spot welding, or the like. The weld region W between the second current collector 176 and the second uncoated portion 146b may be spaced a predetermined distance from the inner surface of the beading portion 180.

[0610] Preferably, 50% or more of the welding region W of the first current collector 144 and the second current collector 176 may overlap with the uniform lamination number section b1 of the folded surface region F. Optionally, the remaining region of the welding region W may overlap with the reduced lamination number section b2 of the folded surface region F. It is more preferable that the entire welding region W overlap with the uniform lamination number section b1 in terms of high welding strength, low resistance at the welding interface, and prevention of damage to the separator and active material layer.

[0611] Preferably, the number of layers of the divided pieces may be 10 to 35 in the uniform layer number section b1 overlapping the welding area W and optionally in the reduced layer number section b2.

[0612] Alternatively, if the number of layers in the divided section of the layer count reduction section b2 overlapping the welding area W is less than 10, the laser power for welding the layer count reduction section b2 may be lower than the laser power for welding the uniform layer count section b1. That is, if the welding area W overlaps the uniform layer count section b1 and the layer count reduction section b2 at the same time, the laser power may be changed depending on the number of layers in the divided section. In this case, the weld strength of the uniform layer count section b1 may be greater than the weld strength of the layer count reduction section b2.

[0613] In the folded surface region F formed on the upper and lower parts of the electrode assembly 110, the radial lengths of the segment-omitted section a1 and / or the segment-height variable section a2 and / or the segment-height uniform section a3 may be the same or different from each other.

[0614] The height of the first portion B1 of the electrode assembly 110 is relatively lower than the other portions. Also, as shown in Fig. 14, the bending length H of the innermost uncoated portion of the third portion B2 is smaller than the sum of the radial length R of the first portion B1 and 10% of the radius of the core 112.

[0615] Therefore, even if the first uncoated portion 146a is bent toward the core, 90% or more of the diameter of the core 112 of the electrode assembly 110 can be exposed to the outside. If the core 112 is not blocked, the electrolyte injection process can be performed without any problems, improving the efficiency of the electrolyte injection. In addition, a welding jig can be inserted through the core 112 to easily perform the welding process between the first current collector 144 and the terminal 172.

[0616] When the first uncoated portion 146a and the second uncoated portion 146b have a divided structure, if the width and / or height and / or spacing pitch of the divided pieces are adjusted to satisfy the numerical range of the above-mentioned embodiment, when the divided pieces are bent, the divided pieces overlap each other to an extent that sufficient welding strength can be ensured, and no empty space (gap) is formed in the folded surface area F.

[0617] Preferably, the first current collector 144 and the second current collector 176 have outer diameters such that the contact areas with the first uncoated portion 146a and the second uncoated portion 146b cover the ends of the folded segments (see 61 and 61' in FIG. 10f) at the final winding turn of the uniform height section a3 of the first and second electrodes. In this case, the folded segments forming the folded surface area F can be welded while being uniformly pressed by the current collectors, and the tightly stacked state of the segments can be maintained even after welding. A tightly stacked state means that there are substantially no gaps between the segments, as shown in FIG. 10a. The tightly stacked state contributes to reducing the resistance of the cylindrical battery 200 to a level suitable for fast charging (e.g., 4 mΩ) or less.

[0618] The structure of the uncoated portions 146a and 146b may be modified to the structure according to the above-described embodiment (variation), and there is no restriction that the conventional uncoated portion structure may be applied to either one of the uncoated portions 146a and 146b.

[0619] FIG. 24 is a cross-sectional view of a cylindrical battery 210 according to yet another embodiment of the present invention, taken along the Y-axis direction.

[0620] 24, a cylindrical battery 210 includes the electrode assembly 100 shown in FIG. 13, and other configurations except for the electrode assembly 100 are substantially the same as the cylindrical battery 140 shown in FIG. 17. Therefore, the configurations described with reference to FIGS. 13 and 17 can be applied substantially in the same manner to this embodiment.

[0621] Preferably, the first uncoated region 146a and the second uncoated region 146b of the electrode assembly 100 are divided into a plurality of segments, and the segments are bent in the radial direction of the electrode assembly 100, for example, from the outer periphery toward the core. In this case, the first portion B1 and the second portion B3 of the first uncoated region 146a are lower in height than the other portions and do not include any segments, so they are not actually bent. The same is true for the second uncoated region 146b.

[0622] In this embodiment, the folded surface region F may also include a segment-free section a1, a segment-height variable section a2, and a segment-height uniform section a3 from the core side to the outer periphery side. However, because the second portion B3 is not folded, the radial length of the folded surface region F may be shorter than in the above-described embodiment.

[0623] As shown in FIGS. 10c, 10d, and 10e, the folded surface region F includes a section a1 where no segment is present and a section b1 where the number of stacked segments is uniform and where the number of stacked segments is 10 or more.

[0624] The folded surface region F may also include a layer count decreasing section b2 adjacent to the second portion B3 of the electrode assembly 110, where the layer count of the segment decreases toward the outer periphery. Preferably, the layer count uniform section b1 may be set as a welding target region.

[0625] In the folded surface region F, the desirable numerical ranges for the ratio (a2 / c) of the height variable section a2 to the radius region (c) including the segment, the ratio (b1 / c) of the uniform number of layers section b1 to the radius region (c) including the segment, and the ratio of the area of the uniform number of layers section b1 to the area of the folded surface region F have been described above, so repeated explanations will be omitted.

[0626] The first current collector 144 may be welded to the bent surface area F of the first non-coating portion 146a, and the second current collector 145 may be welded to the bent surface area F of the second non-coating portion 146b.

[0627] The overlapping relationship between the uniform stack count section b1 and the reduced stack count section b2 and the welding area W, the outer diameters of the first current collector 144 and the second current collector 145, and the configuration in which the first portion B1 does not block more than 10% of the core diameter are essentially as described above.

[0628] On the other hand, the second portion B3 does not include a dividing piece and is shorter in height than the third portion B2. Therefore, when the first uncoated portion 146a is bent, the second portion B3 is not substantially bent. In addition, the second portion B3 is sufficiently spaced apart from the beading portion 147, which solves the problem of the second portion B3 being damaged when the beading portion 147 is pressed in.

[0629] The structure of the uncoated portions 146a and 146b may be modified to the structure according to the above-described embodiment (variation), and there is no restriction that the conventional uncoated portion structure may be applied to either one of the uncoated portions 146a and 146b.

[0630] FIG. 25 is a cross-sectional view of a cylindrical battery 220 according to yet another embodiment of the present invention, taken along the Y-axis direction.

[0631] 25, a cylindrical battery 220 includes the electrode assembly 100 shown in FIG. 24, and other configurations except for the electrode assembly 100 are substantially the same as the cylindrical battery 180 shown in FIG. 21. Therefore, the configurations described with reference to FIGS. 21 and 24 can be applied substantially in the same manner to this embodiment.

[0632] Preferably, the first uncoated region 146a and the second uncoated region 146b of the electrode assembly 100 are divided into a plurality of segments that are bent from the outer periphery toward the core. In this case, the first portion B1 and the second portion B3 of the first uncoated region 146a are shorter than the other portions and do not include a segment structure, so they are not actually bent toward the core. The same is true for the second uncoated region 146b.

[0633] 24, the folded surface region F may include, from the core side to the outer periphery, a segment-free section a1, a segment-height variable section a2, and a segment-height uniform section a3. However, because the second portion B3 is not folded, the radial length of the folded surface region F may be shorter than in the above-described embodiment.

[0634] As shown in FIGS. 10c, 10d, and 10e, the folded surface region F includes a section a1 where no segment is present and a section b1 where the number of stacked segments is uniform and where the number of stacked segments is 10 or more.

[0635] The folded surface region F may also include a layer count decreasing section b2 adjacent to the second portion B3 of the electrode assembly 110, where the layer count of the segment decreases toward the outer periphery. Preferably, the layer count uniform section b1 may be set as a welding target region.

[0636] In the folded surface region F, the desirable numerical ranges for the ratio (a2 / c) of the height variable section a2 to the radius region (c) including the segment, the ratio (b1 / c) of the uniform number of layers section b1 to the radius region (c) including the segment, and the ratio of the area of the uniform number of layers section b1 to the area of the folded surface region F have been described above, so repeated explanations will be omitted.

[0637] The first current collector 144 may be welded to the bent surface area F of the first non-coating portion 146a, and the second current collector 176 may be welded to the bent surface area F of the second non-coating portion 146b.

[0638] The overlapping relationship between the uniform stack count section b1 and the reduced stack count section b2 and the welding area W, the outer diameters of the first current collector 144 and the second current collector 176, and the configuration in which the first portion B1 does not block more than 10% of the core diameter are essentially as described above.

[0639] The structure of the uncoated portions 146a and 146b may be modified to the structure according to the above-described embodiment (variation), and there is no restriction that the conventional uncoated portion structure may be applied to either one of the uncoated portions 146a and 146b.

[0640] In the above-described embodiment (variant), the first current collector 144 and the second current collector 176 included in the cylindrical batteries 170, 180, 200, 220 including the terminal 172 may have an improved structure as shown in Figures 26 and 27.

[0641] The improved structure of the first current collector 144 and the second current collector 176 can contribute to improving the energy density by reducing the resistance of the cylindrical battery and improving vibration resistance. In particular, the first current collector 144 and the second current collector 176 are effective when applied to large cylindrical batteries with a height-to-diameter ratio of greater than 0.4.

[0642] FIG. 26 is a top view showing the structure of a first current collector 144 according to an embodiment of the present invention.

[0643] 23 and 26, the first current collector 144 may include a peripheral portion 144a, a first non-coating portion coupling portion 144b, and a terminal coupling portion 144c. The peripheral portion 144a is disposed on the upper portion of the electrode assembly 110. The peripheral portion 144a has an inner space S therein. openThe peripheral portion 144a may have a substantially rim shape formed thereon. Although the drawings only show the case where the peripheral portion 144a has a substantially circular rim shape, the present invention is not limited thereto. Unlike the illustrations, the peripheral portion 144a may have a substantially square rim shape, a hexagonal rim shape, an octagonal rim shape, or other rim shapes. The number of peripheral portions 144a may be increased to two or more. In this case, another rim-shaped peripheral portion may be included inside the peripheral portion 144a.

[0644] The terminal coupling portion 144c may have a diameter equal to or larger than the diameter of the flat portion 172c formed on the bottom surface of the terminal 172 to ensure a welding area for coupling with the flat portion 172c formed on the bottom surface of the terminal 172.

[0645] The first uncoated portion coupling portion 144b extends inward from the peripheral portion 144a and is coupled to the first uncoated portion 146a by welding. The terminal coupling portion 144c is spaced apart from the first uncoated portion coupling portion 144b and is positioned inside the peripheral portion 144a. The terminal coupling portion 144c may be coupled to a terminal 172 by welding. The terminal coupling portion 144c may be positioned within an inner space S surrounded by the peripheral portion 144a, for example. open The terminal coupling portion 144c may be provided at a position corresponding to a hole formed in the core C of the electrode assembly 110. The terminal coupling portion 144c may cover the hole formed in the core C of the electrode assembly 110 so that the hole formed in the core C of the electrode assembly 110 is not exposed to the outside of the terminal coupling portion 144c. Therefore, the terminal coupling portion 144c may have a diameter or width larger than the hole formed in the core C of the electrode assembly 110.

[0646] The first uncoated portion coupling portion 144b and the terminal coupling portion 144c may be spaced apart and indirectly coupled via the peripheral portion 144a. In this manner, the first current collector 144 has a structure in which the first uncoated portion coupling portion 144b and the terminal coupling portion 144c are not directly coupled but are coupled via the peripheral portion 144a. This allows for dispersion of impacts applied to the coupling portion between the first uncoated portion coupling portion 144b and the first uncoated portion 146a and the coupling portion between the terminal coupling portion 144c and the terminal 172 when shock and / or vibration occurs to the cylindrical battery 200. While four first uncoated portion coupling portions 144b are illustrated in the drawings, the present invention is not limited thereby. The number of first uncoated portion coupling portions 144b may be determined based on the inner space S of the peripheral portion 144a, taking into consideration the difficulty of manufacturing due to the complexity of the shape, electrical resistance, and electrolyte impregnation. open It can be determined in various ways, taking into consideration the above.

[0647] The first current collector 144 may further include a bridge portion 144d extending inward from the peripheral portion 144a and connecting to the terminal coupling portion 144c. The bridge portion 144d may have a cross-sectional area smaller than that of the first non-coating portion coupling portion 144b and the peripheral portion 144a. For example, the bridge portion 144d may have a width and / or thickness smaller than that of the first non-coating portion coupling portion 144b. In this case, electrical resistance increases in the bridge portion 144d. As a result, when current flows through the bridge portion 144d, the relatively large resistance causes a portion of the bridge portion 144d to melt due to overcurrent heating, thereby irreversibly blocking the overcurrent. The cross-sectional area of the bridge portion 144d may be adjusted to an appropriate level in consideration of this overcurrent blocking function.

[0648] The bridge portion 144d may include a tapered portion 144e whose width gradually narrows from the inner surface of the peripheral portion 144a toward the terminal coupling portion 144c. The tapered portion 144e improves the rigidity of the component at the connection portion between the bridge portion 144d and the peripheral portion 144a. The tapered portion 144e allows, for example, a transfer device and / or a worker to grip the tapered portion 144e during the manufacturing process of the cylindrical battery 200, thereby allowing the first current collector 144 and / or the combination of the first current collector 144 and the electrode assembly 110 to be easily and safely transported. That is, the tapered portion 144e can prevent product defects caused by gripping portions to be welded to other components, such as the first uncoated portion coupling portion 144b and the terminal coupling portion 144c.

[0649] The first non-coating portion joining portions 144b may be provided in plurality. The first non-coating portion joining portions 144b may be disposed at equal intervals along the extension direction of the peripheral portion 144a. The extension lengths of the first non-coating portion joining portions 144b may be approximately the same. The first non-coating portion joining portions 144b may be joined to the folded surface region F of the first non-coating portion 146a by laser welding. The welding may be substituted by ultrasonic welding, spot welding, etc.

[0650] The welding pattern 144f formed by welding the first non-coating portion joining portion 144b and the bent surface region F may have a structure extending along the radial direction of the electrode assembly 110. The welding pattern 144f may be an array of lines or dots.

[0651] The welding pattern 144f corresponds to a welding region. Therefore, it is preferable that the welding pattern 144f overlaps with the uniform layer count section b1 of the folded surface region F by 50% or more. The welding pattern 144f that does not overlap with the uniform layer count section b1 may overlap with the reduced layer count section b2. More preferably, the entire welding pattern 144f may overlap with the uniform layer count section b1 of the folded surface region F. It is preferable that the uniform layer count section b1 and optionally the reduced layer count section b2 of the folded surface region F below the point where the welding pattern 144f is formed have a number of laminated sections of 10 or more.

[0652] The terminal coupling portion 144c may be disposed to be surrounded by the plurality of first uncoated portion coupling portions 144b. The terminal coupling portion 144c may be coupled to the flat portion 172c of the terminal 172 by welding. The bridge portion 144d may be located between a pair of adjacent first uncoated portion coupling portions 144b. In this case, the distance from the bridge portion 144d to one of the pair of first uncoated portion coupling portions 144b along the extension direction of the peripheral portion 144a may be approximately the same as the distance from the bridge portion 144d to the other of the pair of first uncoated portion coupling portions 144b along the extension direction of the peripheral portion 144a. The cross-sectional area of each of the plurality of first uncoated portion coupling portions 144b may be approximately the same. The width and thickness of each of the plurality of first uncoated portion coupling portions 144b may be approximately the same.

[0653] Although not shown, a plurality of bridge portions 144d may be provided. Each of the plurality of bridge portions 144d may be disposed between an adjacent pair of first non-coating portion joining portions 144b. The plurality of bridge portions 144d may be disposed at substantially equal intervals from one another along the extension direction of the peripheral portion 144a. The distance from each of the plurality of bridge portions 144d to one of the adjacent pair of first non-coating portion joining portions 144b along the extension direction of the peripheral portion 144a may be substantially the same as the distance to the other first non-coating portion joining portion 144b.

[0654] As described above, when a plurality of first uncoated portion joining portions 144b and / or bridge portions 144d are provided, if the distance between the first uncoated portion joining portions 144b and / or the distance between the bridge portions 144d and / or the distance between the first uncoated portion joining portions 144b and the bridge portions 144d are constant, a current can smoothly flow from the first uncoated portion joining portions 144b to the bridge portions 144d or from the bridge portions 144d to the first uncoated portion joining portions 144b.

[0655] The bridge portion 144d may include a notch N formed to partially reduce the cross-sectional area of the bridge portion 144d. The adjustment of the cross-sectional area of the notch N may be achieved, for example, by partially reducing the width and / or thickness of the bridge portion 144d. When the notch N is provided, the electrical resistance in the region where the notch N is formed increases, thereby enabling rapid current interruption when an overcurrent occurs.

[0656] The notched portion N is preferably provided in a region corresponding to a uniform lamination section of the electrode assembly 110 to prevent foreign matter generated during breakage from entering the electrode assembly 110. This is because the number of laminations of the first uncoated portion 146a is maximized in this region, allowing the overlapping laminations to function as a mask.

[0657] The notched portion N may be wrapped with insulating tape, so that heat generated at the notched portion N is not dissipated to the outside, and therefore the notched portion N breaks more quickly when an overcurrent flows through the bridge portion 144d.

[0658] FIG. 27 is a top view showing the structure of a second current collector 176 according to an embodiment of the present invention.

[0659] 23 and 27, the second current collector 176 is disposed at the bottom of the electrode assembly 110. The second current collector 176 may be configured to electrically connect the uncoated portion 146b of the electrode assembly 110 to the battery housing 171. The second current collector 176 is made of a conductive metal material and is electrically connected to the bent surface region F of the uncoated portion 146b. The second current collector 176 is also electrically connected to the battery housing 171. The second current collector 176 may be fixed by having its periphery interposed between the inner surface of the battery housing 171 and the first gasket 178b. Specifically, the second current collector 176 may be fixed by having its periphery interposed between the lower surface of the beading portion 180 of the battery housing 171 and the first gasket 178b. However, this does not limit the present invention, and instead, the periphery of the second current collector 176 may be welded to the inner wall surface of the battery housing 171 in an area where the beading portion 180 is not formed.

[0660] The second current collector 176 may include a support portion 176a disposed under the electrode assembly 110, a second non-coating portion coupling portion 176b extending from the support portion 176a substantially along the radial direction of the electrode assembly 110 and coupled to the bent surface region F of the non-coating portion 146b, and a housing coupling portion 176c extending from the support portion 176a at an angle toward the inner surface of the battery housing 171 relative to the radial direction of the electrode assembly 110 and coupled to the inner surface. The second non-coating portion coupling portion 176b and the housing coupling portion 176c are indirectly coupled to each other via the support portion 176a and are not directly coupled to each other. Therefore, when an external impact is applied to the cylindrical battery 200 of the present invention, damage to the coupling portions between the second current collector 176 and the electrode assembly 110 and between the second current collector 176 and the battery housing 171 can be minimized. However, the second current collector 176 of the present invention is not limited to having a structure in which the second uncoated portion coupling portion 176b and the housing coupling portion 176c are indirectly coupled. For example, the second current collector 176 may have a structure without the support portion 176a that indirectly couples the second uncoated portion coupling portion 176b and the housing coupling portion 176c and / or a structure in which the uncoated portion 146b and the housing coupling portion 176c are directly coupled.

[0661] The support portion 176a and the second non-coating portion coupling portion 176b are disposed at the bottom of the electrode assembly 110. The second non-coating portion coupling portion 176b is coupled to the folded surface region F of the non-coating portion 146b. Not only the second non-coating portion coupling portion 176b but also the support portion 176a may be coupled to the non-coating portion 146b. The second non-coating portion coupling portion 176b and the folded surface region F of the non-coating portion 146b may be coupled by laser welding. Welding may be replaced by ultrasonic welding, spot welding, or the like. If a beading portion 180 is formed on the battery housing 171, the support portion 176a and the second non-coating portion coupling portion 176b are located above the beading portion 180.

[0662] The support portion 176a includes a current collecting plate hole 176d formed at a position corresponding to a hole formed in the core C of the electrode assembly 110. The core C of the electrode assembly 110 and the current collecting plate hole 176d, which are connected to each other, can function as a passage for inserting a welding rod or irradiating a laser beam for welding between the terminal 172 and the terminal coupling portion 144c of the first current collector 144.

[0663] The current collecting plate hole 176d has a radius r c 0.5r c The radius of the current collecting plate hole 176d may be 0.5r or more. c ~1.0r c In this case, when venting occurs in the cylindrical battery 200, the separator and the electrode winding structure near the core C of the electrode assembly 110 are prevented from being pushed out of the core C by the vent pressure. c When the thickness is larger than 1 / 2 mm, the core C is opened to the maximum extent, which makes it easier to inject the electrolyte in the electrolyte injection step.

[0664] When a plurality of second uncoated portion coupling portions 176b are provided, the plurality of second uncoated portion coupling portions 176b may extend radially from the support portion 176a of the second current collector 176 toward the sidewall of the battery housing 171. The plurality of second uncoated portion coupling portions 176b may be spaced apart from one another along the periphery of the support portion 176a.

[0665] A plurality of the housing coupling portions 176c may be provided. In this case, the plurality of housing coupling portions 176c may extend radially from the center of the second current collector 176 toward the sidewall of the battery housing 171. This allows electrical connection between the second current collector 176 and the battery housing 171 at multiple points. By coupling for electrical connection at multiple points, the coupling area can be maximized and electrical resistance can be minimized. The plurality of housing coupling portions 176c may be spaced apart from one another along the periphery of the support portion 176a. At least one housing coupling portion 176c may be located between adjacent second non-coating portion coupling portions 176b. The plurality of housing coupling portions 176c may be coupled to the inner surface of the battery housing 171, for example, to the beading portion 180. The housing coupling portion 176c may be coupled to the lower surface of the beading portion 180 by laser welding. The welding may be substituted by ultrasonic welding, spot welding, or the like. By welding a plurality of housing coupling portions 176c onto the beading portion 180 in this manner, the current path is dispersed radially, thereby limiting the resistance level of the cylindrical battery 200 to approximately 4 mΩ or less. In addition, by forming the lower surface of the beading portion 180 to extend in a direction approximately parallel to the upper surface of the battery housing 171, i.e., in a direction approximately perpendicular to the sidewall of the battery housing 171, and forming the housing coupling portions 176c to extend in the same direction, i.e., in the radial and circumferential directions, the housing coupling portions 176c can be stably contacted onto the beading portion 180. In addition, because the housing coupling portions 176c are stably contacted onto the flat portions of the beading portion 180 in this manner, welding between the two components is performed smoothly, thereby improving the bonding strength between the two components and minimizing an increase in resistance at the bonding locations.

[0666] The housing coupling portion 176c may include a contact portion 176e coupled to the inner surface of the battery housing 171, and a coupling portion 176f connecting the support portion 176a and the contact portion 176e.

[0667] The contact portion 176e is coupled to an inner surface of the battery housing 171. If a beading portion 180 is formed in the battery housing 171, the contact portion 176e may be coupled to the beading portion 180 as described above. More specifically, the contact portion 176e may be electrically connected to a flat portion formed on the lower surface of the beading portion 180 formed in the battery housing 171, and may be interposed between the lower surface of the beading portion 180 and the first gasket 178b. In this case, for stable contact and coupling, the contact portion 176e may extend a predetermined length in the beading portion 180 along the circumferential direction of the battery housing 171.

[0668] The connecting portion 176f may be bent at an obtuse angle. The bending point may be higher than the middle of the connecting portion 176f. When the connecting portion 176f is bent, the contact portion 176e is stably supported on the flat surface of the beading portion 180. The connecting portion 176f may be divided into a lower portion and an upper portion based on the bending point, and the length of the lower portion may be greater than that of the upper portion. In addition, the inclination angle based on the surface of the support portion 176a may be greater at the lower portion at the bending point than at the upper portion. When the connecting portion 176f is bent, it can buffer pressure (force) applied vertically to the battery housing 171. For example, when pressure is transmitted to the contact portion 176e during the sizing process of the battery housing 171 and the contact portion 176e moves vertically toward the support portion 176a, the bending point of the connecting portion 176f moves upward, deforming the connecting portion 176f, thereby buffering stress.

[0669] Meanwhile, the maximum distance from the center of the second current collector 176 to the end of the second uncoated portion joining portion 176b along the radial direction of the electrode assembly 110 is preferably equal to or smaller than the inner diameter of the battery housing 171 in the region where the beading portion 180 is formed, i.e., the minimum inner diameter of the battery housing 171. This is to prevent the end of the second uncoated portion joining portion 176b from pressing against the end of the electrode assembly 110 during a sizing process in which the battery housing 171 is compressed in the height direction.

[0670] The second non-coating portion joining portion 176b includes holes 176g. The holes 176g can be used as passages for electrolyte movement. A welding pattern 176h formed by welding the second non-coating portion joining portion 176b to the folded surface region F can have a structure extending along the radial direction of the electrode assembly 110. The welding pattern 176h can be an array of lines or dots.

[0671] The welding pattern 176h corresponds to a welding region. Therefore, it is preferable that the welding pattern 176h overlaps the uniform layer count section b1 of the folded surface region F located at the bottom of the electrode assembly 110 by 50% or more. The welding pattern 176h that does not overlap the uniform layer count section b1 may overlap the reduced layer count section b2. More preferably, the entire welding pattern 176h may overlap the uniform layer count section b1 of the folded surface region F. The uniform layer count section b1 and, optionally, the reduced layer count section b2 of the folded surface region F located above the point where the welding pattern 176h is formed preferably have a number of laminated sections of 10 or more.

[0672] The first current collector 144 and the second current collector 176 have different outer diameters. The outer diameter is the outer diameter of the outer edge of the contact area between the folded surface region F and the current collector. The outer diameter is defined as the maximum distance between two points where a line passing through the center of the core C of the electrode assembly intersects with the edge of the contact area. The second current collector 176 is located inside the beading portion 180, so its outer diameter is smaller than that of the first current collector 144. In addition, the length of the welding pattern 144f of the first current collector 144 is longer than the length of the welding pattern 176h of the second current collector 176. Preferably, the welding pattern 144f and the welding pattern 176h may extend radially outward from substantially the same point relative to the center of the core C.

[0673] The cylindrical batteries 170, 180, 200, and 220 according to the present invention may have electrical connections at the top.

[0674] Figure 28 is a top view showing a state in which a plurality of cylindrical batteries 200 are electrically connected, and Figure 29 is a partially enlarged view of Figure 28. The cylindrical battery 200 can be replaced with cylindrical batteries 170, 180, 220 of other structures.

[0675] 28 and 29, a plurality of cylindrical batteries 200 may be connected in series and parallel at the top of the cylindrical batteries 200 using bus bars 210. The number of cylindrical batteries 200 may be increased or decreased depending on the capacity of the battery pack.

[0676] In each cylindrical battery 200, the terminal 172 may have a positive polarity, and the flat surface 171a of the battery housing 171 around the terminal 172 may have a negative polarity. Of course, the opposite is also possible.

[0677] Preferably, a plurality of cylindrical batteries 200 may be arranged in a plurality of rows and columns. In the drawing, columns are provided in the vertical direction, and rows are provided in the horizontal direction. Furthermore, to maximize space efficiency, the cylindrical batteries 200 may be arranged in the closest packing structure. The closest packing structure is formed when an equilateral triangle is drawn when the centers of the terminals 172 exposed to the outside of the battery housing 171 are connected to each other. Preferably, the bus bars 210 connect the cylindrical batteries 200 arranged in the same column in parallel with each other, and connect the cylindrical batteries 200 arranged in two adjacent columns in series with each other.

[0678] Preferably, bus bar 210 may include a body portion 211, a plurality of first bus bar terminals 212, and a plurality of second bus bar terminals 213 for series and parallel connection.

[0679] The body portion 211 may extend along the row of cylindrical batteries 200 between adjacent terminals 172. Alternatively, the body portion 211 may extend along the row of cylindrical batteries 200 but may be bent regularly, such as in a zigzag shape.

[0680] The plurality of first bus bar terminals 212 may extend from one side of the body portion 211 and be electrically coupled to the terminals 172 of the cylindrical battery 200 located on the one side. The electrical coupling between the first bus bar terminals 212 and the terminals 172 may be performed by laser welding, ultrasonic welding, or the like.

[0681] A plurality of second bus bar terminals 213 may extend from the other side of the body portion 211 and be electrically connected to the flat surface 171a around the terminals 172 located on the other side. The electrical connection between the second bus bar terminals 213 and the flat surface 171a may be performed by laser welding, ultrasonic welding, or the like.

[0682] Preferably, the body portion 211, the plurality of first bus bar terminals 212, and the plurality of second bus bar terminals 213 may be formed from a single conductive metal plate. The metal plate may be, for example, an aluminum plate or a copper plate, but the present invention is not limited thereto. Alternatively, the body portion 211, the plurality of first bus bar terminals 212, and the second bus bar terminals 213 may be manufactured as separate pieces and then joined together by welding or the like.

[0683] The cylindrical battery 200 of the present invention described above has a structure in which resistance is minimized by expanding the welding area through the bent surface area F, multiple current paths using the second current collector 176, and minimizing the length of the current paths. The AC resistance of the cylindrical battery 200 measured by a resistance meter between the positive and negative electrodes, i.e., between the terminal 172 and the surrounding flat surface 171a, may be 0.5mΩ to 4mΩ, and preferably 1mΩ to 4mΩ, which is suitable for fast charging.

[0684] In the cylindrical battery 200 according to the present invention, the terminal 172 having a positive polarity and the flat surface 171a having a negative polarity are positioned in the same direction, so that electrical connection between the cylindrical batteries 200 can be easily realized using the bus bar 210.

[0685] In addition, since the terminal 172 of the cylindrical battery 200 and the surrounding flat surface 171a have a large area, the connection area of the bus bar 210 can be sufficiently secured, thereby sufficiently reducing the resistance of the battery pack including the cylindrical battery 200.

[0686] In addition, since electrical wiring can be performed on the top of the cylindrical battery 200, the energy density per unit volume of the battery module / pack can be maximized.

[0687] The cylindrical battery according to the above-described embodiment (variant) is used to manufacture a battery pack.

[0688] FIG. 30 is a diagram schematically illustrating the configuration of a battery pack according to an embodiment of the present invention.

[0689] 30, a battery pack 300 according to an embodiment of the present invention includes an assembly of electrically connected cylindrical batteries 301 and a pack housing 302 that accommodates the assembly. The cylindrical batteries 301 may be any one of the batteries according to the above-described embodiments (variants). For convenience of illustration, components such as bus bars for electrical connection of the cylindrical batteries 301, a cooling unit, and external terminals are not shown.

[0690] The battery pack 300 is mounted on a vehicle. The vehicle may be, for example, an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle. The vehicle may be a four-wheeled vehicle or a two-wheeled vehicle.

[0691] FIG. 31 is a diagram illustrating a vehicle including the battery pack 300 of FIG.

[0692] 31, a vehicle V according to an embodiment of the present invention includes a battery pack 300 according to an embodiment of the present invention. The vehicle V operates by receiving power from the battery pack 300 according to an embodiment of the present invention.

[0693] According to the present invention, the uncoated portions protruding from the upper and lower portions of the electrode assembly are used as electrode tabs, thereby reducing the internal resistance of the battery and increasing the energy density.

[0694] According to another aspect of the present invention, the structure of the uncoated portion of the electrode assembly is improved to prevent interference between the electrode assembly and the inner surface of the battery housing during the process of forming the beading portion of the battery housing, thereby preventing internal short circuits in a cylindrical battery due to partial deformation of the electrode assembly.

[0695] According to yet another aspect of the present invention, the structure of the uncoated portion of the electrode assembly is improved to prevent the uncoated portion from being torn when bent, and the number of overlapping layers of the uncoated portion is sufficiently increased to improve the welding strength of the current collector.

[0696] According to yet another aspect of the present invention, by applying a segment structure to the uncoated portion of the electrode and optimizing the dimensions (width, height, and spacing pitch) of the segments, the number of segments stacked in the area used as the welding target area can be sufficiently increased, thereby improving the physical properties of the area where the current collector is welded.

[0697] According to yet another aspect of the present invention, an electrode assembly having improved energy density and reduced resistance can be provided by applying a structure in which a current collector is welded over a wide area to a folded surface region formed by folding a segment.

[0698] According to yet another aspect of the present invention, a cylindrical battery having an improved design for electrical wiring at the top can be provided.

[0699] According to yet another aspect of the present invention, the structure of the uncoated portion adjacent to the core of the electrode assembly is improved to prevent the cavity in the core of the electrode assembly from being blocked when the uncoated portion is bent, thereby facilitating the electrolyte injection process and the welding process between the battery housing (or terminal) and the current collector.

[0700] According to yet another aspect of the present invention, there can be provided a cylindrical battery having a structure in which internal resistance is low, internal short circuits are prevented, and welding strength between a current collector and a non-coating portion is improved, as well as a battery pack and a vehicle including the same.

[0701] In particular, the present invention can provide a cylindrical battery having a height-to-diameter ratio of 0.4 or more and a resistance of 4 mΩ or less, a battery pack including the same, and a vehicle.

[0702] As described above, the present invention has been described using limited embodiments and drawings, but the present invention is not limited thereto, and it goes without saying that various modifications and variations can be made by a person having ordinary skill in the art to which the present invention pertains within the technical spirit of the present invention and the equivalent scope of the claims.

Claims

1. An electrode assembly in which a first electrode, a second electrode, and a separator interposed therebetween are wound around a winding shaft to define a core and an outer circumferential surface, The first electrode includes a first active material portion coated with an active material layer along a winding direction, and a first uncoated portion not coated with an active material layer, At least a portion of the first uncoated portion is defined as an electrode tab; the first uncoated portion includes a first portion adjacent to the core of the electrode assembly, a second portion adjacent to an outer peripheral surface of the electrode assembly, and a third portion between the first portion and the second portion, The electrode assembly, wherein the first portion or the second portion has a height that is lower than the third portion in the winding axis direction.

2. The electrode assembly according to claim 1 , wherein the third portion is defined as the electrode tab when folded along the radial direction of the electrode assembly.

3. The electrode assembly according to claim 1 , wherein the second portion and the third portion are defined as the electrode tabs when folded along a radial direction of the electrode assembly.

4. The electrode assembly according to claim 1 , wherein at least a portion of the third portion is divided into a plurality of independently bendable segments.

5. The electrode assembly according to claim 4 , wherein each of the plurality of segments has a geometric shape formed by connecting one or more straight lines, one or more curved lines, or a combination thereof.

6. 6. The electrode assembly of claim 5, wherein each of the plurality of segments has a lower width greater than an upper width.

7. 6. The electrode assembly according to claim 5, wherein each of the plurality of segments has a lower width equal to an upper width.

8. 6. The electrode assembly of claim 5, wherein each of the plurality of segments decreases in width from bottom to top.

9. 6. The electrode assembly of claim 5, wherein each of the plurality of segments decreases in width and then increases in width from bottom to top.

10. 6. The electrode assembly of claim 5, wherein each of the plurality of segments increases and then decreases in width from bottom to top.

11. 6. The electrode assembly of claim 5, wherein each of the plurality of segments increases in width from bottom to top and then remains constant.

12. 6. The electrode assembly of claim 5, wherein each of the plurality of segments has a width that decreases from bottom to top and then remains constant.

13. The electrode assembly according to claim 5 , wherein the lower interior angles of the plurality of segments increase individually, in groups, or in units of a plurality of groups in one direction parallel to the winding direction.

14. 14. The electrode assembly of claim 13, wherein the lower interior angles of the plurality of segments increase individually, in groups, or in units of multiple groups in a range of 60° to 85° in one direction parallel to the winding direction.

15. Each of the plurality of segments has a geometric shape whose width decreases from bottom to top. and the electrode assembly is wound around the core with a radius of r. The lower interior angle θ of the intercept falls within the angle range of the following formula: [Equation 1] 5. The electrode assembly of claim 4, wherein D is the width of the segment in the winding direction, r is the radius of the winding turn including the segment, H is the height of the segment, and p is the spacing pitch of the segment.

16. The electrode assembly according to claim 5 , wherein each of the plurality of segments has a side that is straight, curved, or a combination thereof.

17. 6. The electrode assembly according to claim 5, wherein each of the plurality of segments has a side that is convex outward or convex inward.

18. The electrode assembly according to claim 5 , wherein each of the plurality of segments has a rounded upper corner.

19. The electrode assembly according to claim 5 , wherein the geometric shapes of the plurality of segments vary individually, in groups, or in groups of two or more groups along a direction parallel to the winding direction.

20. 20. The electrode assembly according to claim 4, wherein a cutting groove is interposed between adjacent segments along the winding direction, and a lower portion of the cutting groove includes a bottom portion and rounded portions connecting both ends of the bottom portion to side edges of the segments on both sides of the cutting groove.

21. The electrode assembly according to claim 20, wherein the radius of curvature of the rounded portion is greater than 0 mm and not greater than 0.1 mm.

22. The electrode assembly according to claim 20, wherein the radius of curvature of the rounded portion is 0.01 mm to 0.05 mm.

23. 23. The electrode assembly of claim 20, wherein the bottom is flat.

24. 24. The electrode assembly of claim 20, wherein a separation pitch defined as a distance between two points where a line extending from the side edges of the two segment pieces located on both sides of the kerf intersects with a line extending from the bottom of the kerf is 0.05 mm to 1.00 mm.

25. 24. The electrode assembly of claim 20, wherein the plurality of segments are made of aluminum foil, and a spacing pitch defined as a distance between two points where a line extending from a side edge of each of the segments located on either side of the cutting groove intersects with a line extending from a lower end of the cutting groove is 0.5 mm to 1.00 mm.

26. 26. The electrode assembly of claim 20, wherein the spacing pitch of the plurality of segments, defined as the distance between two points where a line extending from the side edges of the two segments located on either side of the cutting groove intersects with a line extending from the bottom of the cutting groove, varies along one direction parallel to the winding direction.

27. 27. The electrode assembly of claim 26, wherein the separation pitch of the plurality of segments varies by group or by two or more groups.

28. 28. The electrode assembly according to claim 20, wherein the bottom of the cutting groove is spaced a predetermined distance from the active material layer.

29. The electrode assembly of claim 28, wherein a distance between the bottom of the cutting groove and the active material layer is 0.2 mm to 4 mm.

30. 29. The electrode assembly of claim 28, wherein a distance between the bottom of the cut groove and the active material layer varies along a direction parallel to the winding direction.

31. The electrode assembly of claim 30 , wherein a distance between the bottom of the cut groove and the active material layer varies individually, in groups, or in two or more groups along a direction parallel to the winding direction.

32. 32. The electrode assembly according to claim 20, wherein the plurality of segments are bent in a radial direction of the electrode assembly in a section of 0 to 1 mm above the bottom of the cutting groove.

33. 33. The electrode assembly according to claim 4, wherein each of the plurality of segments has an arc formed by the lower end of the segment with an inclination angle of 45° or less relative to the core center of the electrode assembly.

34. When the radius of the winding turn including the segment based on the core center of the electrode assembly is defined as r and the width of the segment in the winding direction is defined as D(r), D(r) can be calculated by the following equation: 1≦D(r)≦(2×π×r / 360°)×45° The electrode assembly according to any one of claims 4 to 33, wherein

35. 35. The electrode assembly of claim 34, wherein the width D(r) of each of the plurality of segments in the winding direction increases or decreases gradually or stepwise as the radius r of the winding turn in which the segment is located increases relative to the core center of the electrode assembly.

36. 35. The electrode assembly of claim 34, wherein the width D(r) of each of the plurality of segments in the winding direction gradually or stepwise increases and then gradually or stepwise decreases as the radius r of the winding turn in which the segment is located increases relative to the core center of the electrode assembly, or vice versa.

37. 34. The electrode assembly of claim 33, wherein each of the plurality of segments has a substantially identical circumferential angle relative to a core center of the electrode assembly.

38. 34. The electrode assembly of claim 33, wherein the widths of the plurality of segments increase at substantially the same rate in a direction parallel to the winding direction of the electrode assembly.

39. 39. The electrode assembly of claim 4, wherein the width of each of the plurality of segments in the winding direction increases gradually or stepwise within a range of 1 mm to 11 mm as the radius r of the winding turn on which the segment is located increases relative to the core center of the electrode assembly.

40. The electrode assembly of claim 1 , wherein the height of at least a section of the third portion in the winding axis direction changes gradually or stepwise in one direction parallel to the winding direction.

41. The electrode assembly of claim 40 , wherein the height of at least a portion of the second portion and the third portion in the winding axial direction increases gradually or stepwise in one direction parallel to the winding direction.

42. 41. The electrode assembly of claim 40, wherein the third portion is divided into a plurality of regions having different heights along a direction parallel to the winding direction, and the heights of the uncoated portions in the plurality of regions increase stepwise along the direction parallel to the winding direction.

43. The first uncoated portion has a first height h along a direction parallel to the winding direction. １ ~ N-1th height h Ｎ－１ (N is a height index and is a natural number equal to or greater than 2) Ｎ (h Ｎ－１ 5. The electrode assembly of claim 4, further comprising a uniform height section that is maintained uniformly over a range of heights (larger than the width of the electrode).

44. 44. The electrode assembly of claim 43, wherein N is 2 to 30.

45. The height h ｋ (k is a natural number from 1 to N) and the number of segments having a height h ｋ 45. The electrode assembly of claim 43 or 44, wherein the plurality of segments having the same are arranged in one or more winding turns.

46. Height h ｋ (k is a natural number from 1 to N) The starting radius of the winding turn including the segment having the above-mentioned shape is defined as r ｋ When the core of the electrode assembly is defined as ｋ 46. The electrode assembly of claim 43, wherein 90% or more of the diameter is not obstructed by the bent portion of the segment located at .

47. Height h ｋ (k is a natural number from 1 to N) The starting radius of the winding turn containing the segment is r ｋ , the radius of the core is r ｃ Then, the height of the segment h ｋ is the following formula 2 mm ≦ h ｋ ≦r ｋ -α×r ｃ (α is between 0.90 and 1) 47. The electrode assembly according to any one of claims 43 to 46, wherein

48. 5. The electrode assembly of claim 4, wherein the electrode assembly includes, in a cross section taken along the winding axis, a segment-free section in which no segments are present, a height-variable section in which the height of the segments varies, and a height-uniform section in which the height of the segments is uniform, and the segments are arranged in the height-variable section and the height-uniform section, and are bent along the radial direction of the electrode assembly to form a bent surface region.

49. 49. The electrode assembly of claim 48, wherein the first portion is not divided into segments, and the segment-omitted section corresponds to the first portion.

50. 49. The electrode assembly of claim 48, wherein the third portion is divided into a plurality of independently bendable segments, and the variable height section and the uniform height section correspond to the third portion.

51. 49. The electrode assembly of claim 48, wherein the second portion and the third portion are divided into a plurality of sections that can be bent independently, and the variable height section and the uniform height section correspond to the second portion and the third portion.

52. In the variable height section and the uniform height section, the maximum height h of the segment ｍａｘ satisfies the following formula, h ｍａｘ ≦W ｆｏｉｌ -W ｓｃｒａｐ，ｍｉｎ -W ｍａｒｇｉｎ，ｍｉｎ -W ｇａｐ W ｆｏｉｌ is the width of the current collector foil before the segments are formed, and W ｓｃｒａｐ，ｍｉｎ is the width corresponding to the minimum cutting scrap margin when cutting the current collector foil to form cut pieces, and W ｍａｒｇｉｎ，ｍｉｎ is the width corresponding to the minimum meandering margin of the separation membrane, and W ｇａｐ 52. The electrode assembly of claim 48, wherein ∇ is a width corresponding to an insulating gap between an end of the second electrode facing the first electrode across the separator and an end of the separator.

53. When the first electrode is a positive electrode, the insulating gap W ｇａｐ 53. The electrode assembly of claim 52, wherein is 0.2 mm to 6 mm.

54. When the first electrode is a negative electrode, the insulating gap W ｇａｐ 53. The electrode assembly of claim 52, wherein is 0.1 mm to 2 mm.

55. The minimum cutting scrap margin W ｓｃｒａｐ，ｍｉｎ 53. The electrode assembly of claim 52, wherein is 1.5 mm to 8 mm.

56. The minimum meandering margin W of the separation membrane ｍａｒｇｉｎ，ｍｉｎ 53. The electrode assembly of claim 52, wherein is 0 to 1 mm.

57. 53. The electrode assembly of claim 52, wherein the minimum cutting scrap margin is zero.

58. 58. The electrode assembly of claim 48, wherein the height of the segments arranged in the height-variable section increases gradually or stepwise within a range of 2 mm to 10 mm.

59. 59. The electrode assembly of claim 48, wherein the ratio of the radial length of the segment-omitted section to the radius of the electrode assembly excluding the core is 10% to 40% in the radial direction of the electrode assembly.

60. 60. The electrode assembly of claim 48, wherein a ratio of the radial length of the variable height section to the radial lengths corresponding to the variable height section and the uniform height section in the radial direction of the electrode assembly is 1% to 50%.

61. 61. The electrode assembly according to claim 48, wherein a ratio of a length of the electrode region corresponding to the segment-omitted section to an entire length of the first electrode is 1% to 30%.

62. 62. The electrode assembly of claim 48, wherein a ratio of a length of the electrode region corresponding to the height variable section to an entire length of the first electrode is 1% to 40%.

63. 63. The electrode assembly of claim 48, wherein a ratio of a length of the electrode region corresponding to the uniform height section to an entire length of the first electrode is 50% to 90%.

64. The electrode assembly of claim 4 , wherein at least one of a width in the winding direction and a height in the winding axial direction of the plurality of segments increases stepwise or continuously in one direction parallel to the winding direction.

65. 5. The electrode assembly of claim 4, wherein at least one of a width in the winding direction and a height in the winding axial direction of the plurality of segments increases stepwise or continuously and then decreases stepwise or continuously, or vice versa, in one direction parallel to the winding direction.

66. 5. The electrode assembly of claim 4, wherein the plurality of segments form a plurality of segment groups along a direction parallel to the winding direction of the electrode assembly, and the segments belonging to the same segment group have substantially the same width in the winding direction and height in the winding axis direction.

67. 67. The electrode assembly of claim 66, wherein at least one of the width in the winding direction and the height in the winding axis direction of the segments belonging to the same segment group increases gradually or stepwise toward a direction parallel to the winding direction of the electrode assembly.

68. 62. The electrode assembly of claim 61, wherein the lower interior angles of the segments belonging to the same segment group increase gradually or stepwise in a group or in two or more groups in a direction parallel to the winding direction of the electrode assembly.

69. The electrode assembly of claim 66, comprising a combination of sub-segment groups in which W3 / W2 is smaller than W2 / W1, where W1, W2, and W3 are the winding direction widths for each of three sub-segment groups that are consecutively adjacent in one direction parallel to the winding direction of the electrode assembly.

70. 70. The electrode assembly of claim 1, wherein the first portion is not divided into segments and the first portion is not bent along a radial direction of the electrode assembly.

71. 70. The electrode assembly of claim 1, wherein the second portion is not divided into segments and the second portion is not bent along a radial direction of the electrode assembly.

72. 21. The electrode assembly of claim 20, wherein an insulating coating layer is formed at a boundary between the active material layer and an uncoated region present in a section where the bottom of the cut groove and the active material layer are separated.

73. 73. The electrode assembly of claim 72, wherein the insulating coating layer comprises a polymeric resin and an inorganic filler dispersed in the polymeric resin.

74. 74. The electrode assembly according to claim 72 or 73, wherein the insulating coating layer is formed to cover a boundary portion between the active material layer and the first uncoated portion along the winding direction.

75. 75. The electrode assembly of claim 74, wherein the insulating coating layer is formed to cover a boundary portion between the active material layer and the first uncoated portion with a width of 0.3 to 5 mm along the winding axis.

76. 76. The electrode assembly according to claim 72, wherein an end of the insulating coating layer is located within a range of −2 mm to 2 mm along the winding axis direction relative to an end of the separator.

77. 77. The electrode assembly of claim 76, wherein the insulating coating layer is exposed to the exterior of the separator.

78. 78. The electrode assembly of any one of claims 72 to 77, wherein the lower end of the cutting groove and the insulating coating layer are spaced apart by a distance of 0.5 mm to 2 mm.

79. 79. The electrode assembly according to claim 78, wherein an end of the insulating coating layer in the winding axis direction is located within a range of −2 mm to +2 mm from a lower end of the cutting groove.

80. 80. The electrode assembly of claim 72, wherein the distance between the lower end of the cutting groove and the insulating coating layer of the plurality of cut pieces varies along a direction parallel to the winding direction.

81. 81. The electrode assembly of claim 80, wherein the separation distances of the plurality of segments vary individually, in groups, or in groups of two or more.

82. 82. The electrode assembly of claim 72, wherein the second electrode includes a second active material portion coated with an active material layer along the winding direction, and an end of the second active material portion is located between an upper end and a lower end of the insulating coating layer in the winding axis direction.

83. 83. The electrode assembly of claim 1, wherein the third portion and, optionally, the second portion are divided into a plurality of segments that can be bent independently, and the electrode assembly includes a folded surface region formed by bending the plurality of segments along a radial direction of the electrode assembly.

84. 84. The electrode assembly of claim 83, wherein the number of laminations of the segment pieces at a radial position of the folded surface region is defined as the number of laminations of the segment pieces that intersect with a virtual line parallel to the winding axis direction at the radial position of the folded surface region relative to the core center of the electrode assembly, and the folded surface region includes a uniform lamination number section in which the number of laminations of the segment pieces is uniform from the core side to the outer periphery, and a decreasing lamination number section located outside the uniform lamination number section in which the number of laminations of the segment pieces decreases toward the outer periphery.

85. 85. The electrode assembly of claim 84, wherein radial lengths of the uniform lamination number section and the reduced lamination number section with respect to a core center of the electrode assembly correspond to a radial length of a radial section in which a winding turn including the plurality of division segments is located.

86. 85. The electrode assembly of claim 84, wherein the electrode assembly includes, sequentially along the radial direction, a segment-free section where no segments are present, a height-variable section where the height of the segments varies, and a uniform height section where the height of the segments is uniform, and the radius at which the uniform stack number section starts relative to a core center of the electrode assembly corresponds to the radius at which the height-variable section starts.

87. The electrode assembly according to any one of claims 84 to 86, wherein the number of stacked segments in the uniform stacking section is 10 to 35.

88. 88. The electrode assembly of claim 84, wherein the first electrode is a positive electrode, and the thickness of the divided pieces in the uniform stacking number section is 100 μm to 875 μm.

89. 88. The electrode assembly of claim 84, wherein the first electrode is a negative electrode, and the thickness of the divided pieces in the uniform stacking number section is 50 μm to 700 μm.

90. 90. The electrode assembly of claim 84, wherein a ratio of the radial length of the uniform lamination number section to the radial lengths of the uniform lamination number section and the decreasing lamination number section is 30% to 85%.

91. 91. The electrode assembly of claim 84, further comprising a current collector welded to the bent surface region, wherein the welded region of the current collector overlaps with the uniform stack number section by at least 50% in the radial direction of the electrode assembly.

92. 92. The electrode assembly of claim 91, wherein a region of the welding region of the current collector that does not overlap with the uniform lamination number section overlaps with the reduced lamination number section in the radial direction of the electrode assembly.

93. 93. The electrode assembly of claim 91 or 92, wherein the peripheral edge of the current collector is welded to the folded surface region while being disposed on the folded surface region so as to cover an end of the folded portion of the radially outermost portion of the electrode assembly.

94. The welding strength of the welded area of the current collector is 2 kgf / cm ２ 94. The electrode assembly according to any one of claims 91 to 93.

95. The welding strength of the welded area of the current collector is 4 kgf / cm ２ 94. The electrode assembly according to any one of claims 91 to 93.

96. the first uncoated portion is made of metal foil, The metal foil has an elongation ratio of 1.5% to 3.0% and a tensile strength of 25 kgf / mm ２ ~35 kgf / mm ２ 96. The electrode assembly of any one of claims 1 to 95, wherein:

97. 97. The electrode assembly of claim 96, wherein the metal foil is aluminum foil.

98. 97. The electrode assembly of claim 96, wherein the camber length of the first electrode is less than 20 mm.

99. 99. The electrode assembly of claim 1, wherein the ratio of the length of the short side parallel to the winding axis direction to the length of the long side parallel to the winding direction of the first active material part is 1% to 4%.

100. 100. The electrode assembly of claim 1, wherein the second portion has a height that decreases stepwise or gradually from the core side to the outer periphery side of the electrode assembly.

101. 101. The electrode assembly of claim 1, wherein the second portion and the third portion are divided into a plurality of segments that can be bent independently, and the segments included in the second portion are larger than the segments included in the third portion in at least one of width in the winding direction and height in the winding axis direction.

102. The electrode assembly according to claim 4 , wherein the third portion includes a section in which no segment is present along the winding direction of the electrode assembly.

103. The third portion includes a plurality of segment-omitted sections along one direction parallel to the winding direction.

103. The electrode assembly of claim 102.

104. 104. The electrode assembly of claim 103, wherein the width of each of the plurality of segment-omitted sections increases or decreases along one direction parallel to the winding direction.

105. 105. The electrode assembly of claim 102, wherein the height of the uncoated portion of the segment-omitted section is substantially the same as the height of the uncoated portion of the first portion or the uncoated portion of the second portion.

106. 106. The electrode assembly of claim 102, wherein the plurality of segments are positioned within a predetermined circumferential angle range relative to the core center of the electrode assembly.

107. 107. The electrode assembly of claim 102, wherein the plurality of segments are located in two or more sector-shaped or polygonal regions arranged circumferentially relative to the core center of the electrode assembly.

108. 108. The electrode assembly of claim 107, wherein the circular angle of the sectorial region is 20° or greater.

109. 109. The electrode assembly of claim 1, wherein the second electrode includes a second active material portion coated with an active material layer along the winding direction and a second uncoated portion not coated with an active material layer, at least a portion of the second uncoated portion being defined as an electrode tab, the second uncoated portion including a section divided into a plurality of segments that can be bent independently, and the plurality of segments are bent along a radial direction of the electrode assembly to form a bent surface region.

110. An electrode assembly in which a first electrode, a second electrode, and a separator interposed therebetween are wound around a winding shaft to define a core and an outer circumferential surface, The first electrode includes a first active material portion coated with an active material layer along a winding direction, and a first uncoated portion not coated with an active material layer, The first uncoated portion includes a section divided into a plurality of segments that can be independently bent from a core side toward an outer periphery side of the electrode assembly, the plurality of segments are bent along a radial direction of the electrode assembly to form bent surface regions; The folded surface region includes a uniform stacking number section in which the number of stacked segments of the segment is 10 or more along the radial direction, and a decreasing stacking number section located adjacent to the uniform stacking number section, in which the number of stacked segments of the segment decreases as the section moves away from the uniform stacking number section.

111. The electrode assembly of claim 110, comprising, sequentially along the radial direction of the electrode assembly, a segment-free section where no segments exist, a height-variable section where the height of the segments increases stepwise, and a height-uniform section where the height of the segments is uniform, and the starting radius of the uniform stack number section relative to the core center of the electrode assembly corresponds to the starting radius of the height-variable section.

112. The electrode assembly of claim 111, wherein the first uncoated area adjacent to the core side is not divided into segments and is arranged in the winding turn of the segment-omitted section.

113. The electrode assembly of claim 111 or 112, wherein a ratio of the radial length of the uniform lamination number section to the radial lengths of the uniform lamination number section and the decreasing lamination number section is 30% to 85%.

114. The electrode assembly of any one of claims 111 to 113, wherein the ratio of the length of the electrode region corresponding to the segment-omitted section to the entire length of the first electrode along the winding direction is 1% to 30%.

115. The electrode assembly of any one of claims 111 to 114, wherein a ratio of the length of the electrode region corresponding to the height variable section to the entire length of the first electrode along the winding direction is 1% to 40%.

116. The electrode assembly of any one of claims 111 to 115, wherein a ratio of a length of the electrode region corresponding to the uniform height section to an entire length of the first electrode along the winding direction is 50% to 90%.

117. 117. The electrode assembly of claim 110, wherein in the sections divided into the plurality of segments, at least one selected from the width in the winding direction of the segment, the height in the winding axial direction, and the lower interior angle increases stepwise along a direction parallel to the winding direction.

118. 118. The electrode assembly of claim 110, wherein a height of a first uncoated region adjacent to a core side or an outer periphery side of the electrode assembly is lower than a height of the plurality of segment pieces.

119. An electrode assembly as described in any one of claims 110 to 118, wherein the plurality of segments are bent toward the core side of the electrode assembly, and 90% or more of the diameter of the core of the electrode assembly is not blocked by the bent portion of the segment located closest to the core side of the electrode assembly.

120. An electrode assembly in which a positive electrode, a negative electrode, and a separator interposed therebetween are wound around a winding shaft to define a core and an outer circumferential surface, The positive electrode includes a first active material portion coated with an active material layer along a winding direction, and a first uncoated portion not coated with an active material layer, At least a part of the first uncoated portion is used as an electrode tab, The first uncoated portion includes a plurality of segments that can be independently bent from the core side toward the outer periphery of the electrode assembly, The plurality of segments are folded along the radial direction of the electrode assembly and stacked in multiple layers to form a folded surface region; The folded surface region includes a uniform lamination number section in which the number of laminations of the divided segments is uniform along the radial direction, and a decreasing lamination number section located adjacent to the uniform lamination number section, in which the number of laminations of the divided segments decreases as the distance from the uniform lamination number section increases, The thickness of the laminated pieces in the uniform laminated number section is 100 μm to 875 μm.

121. An electrode assembly in which a positive electrode, a negative electrode, and a separator interposed therebetween are wound around a winding shaft to define a core and an outer circumferential surface, The negative electrode includes a first active material portion coated with an active material layer along a winding direction, and a first uncoated portion not coated with an active material layer, At least a part of the first uncoated portion is used as an electrode tab, The first uncoated portion includes a plurality of segments that can be independently bent from the core side toward the outer periphery of the electrode assembly, The plurality of segments are folded along the radial direction of the electrode assembly and stacked in multiple layers to form a folded surface region; The folded surface region includes a uniform lamination number section in which the number of laminations of the divided segments is uniform along a radial direction, and a decreasing lamination number section located adjacent to the uniform lamination number section, in which the number of laminations of the divided segments decreases as the distance from the uniform lamination number section increases, The thickness of the laminated pieces in the uniform laminated number section is 50 μm to 700 μm.

122. an electrode assembly in which a core and an outer circumferential surface are defined by winding a first electrode, a second electrode, and a separator interposed therebetween around a winding shaft, the first electrode including a first active material portion coated with an active material layer along the winding direction and a first uncoated portion not coated with the active material layer, at least a portion of the first uncoated portion itself being defined as an electrode tab, the first uncoated portion including a first portion adjacent to the core of the electrode assembly, a second portion adjacent to the outer circumferential surface of the electrode assembly, and a third portion between the first and second portions, the first portion or the second portion having a lower height in the winding axis direction than the third portion; a battery housing including an open end and a bottom portion facing the open end, the battery housing accommodating the electrode assembly in a space between the open end and the bottom, the battery housing being electrically connected to one of the first electrode and the second electrode and having a first polarity; a seal that seals the open end of the battery housing; a terminal electrically connected to the other of the first electrode and the second electrode, the terminal having a surface exposed to the outside and a second polarity.

123. 123. The battery of claim 122, wherein the second portion is lower in height in the winding axial direction than the third portion, the battery housing has a beading portion pressed inward in an area adjacent to the open end, and the inner circumferential surface of the beading portion facing the upper end of the electrode assembly and the second portion are spaced apart by a predetermined distance.

124. 124. The battery of claim 123, wherein the indentation depth D1 of the beading portion and the distance D2 from the inner circumferential surface of the battery housing to the boundary point between the second portion and the third portion satisfy the relationship D1≦D2.

125. a current collector electrically connected to the third portion; 125. The battery of claim 123 or 124, further comprising an insulator covering the current collector and having a periphery interposed and fixed between the inner circumferential surface of the beading portion and the current collector.

126. 126. The battery of claim 125, wherein the diameter of the current collector is smaller than the smallest inner diameter of the inner circumferential surface of the beading portion, and the diameter of the current collector is the same as or larger than the outermost diameter of the third portion.

127. 126. The battery of claim 125, wherein the current collector is positioned higher than the beading portion in the winding axis direction.

128. A battery described in any one of claims 122 to 127, wherein the sealing body includes a cap that seals the open end of the battery housing, a gasket interposed between the periphery of the cap and the open end of the battery housing, and a crimping portion that extends inside the battery housing and is bent to wrap around and secure the periphery of the cap together with the gasket, and the terminal having the second polarity is the cap.

129. 129. The battery of any one of claims 122 to 128, further comprising a first current collector electrically connected to the first plain portion, wherein the terminal is a rivet terminal insulatively attached to a through hole formed in the bottom of the battery housing, electrically connected to the first current collector, and having the second polarity.

130. 130. The battery of claim 129, further comprising an insulator interposed between the inner surface of the bottom of the battery housing and the upper surface of the first current collector to electrically insulate the inner surface of the bottom of the battery housing from the first current collector.

131. 131. The battery of claim 130, wherein the insulator has a thickness corresponding to the distance between the inner surface of the bottom of the battery housing and the top surface of the first current collector, and is in close contact with the inner surface of the bottom of the battery housing and the top surface of the first current collector.

132. 131. The battery of claim 130, wherein the terminal includes a flat portion at a bottom end, the insulator includes an opening exposing the flat portion, and the flat portion is welded to the first current collector through the opening.

133. The battery of any one of claims 122 to 132, wherein the second electrode includes a second active material portion coated with an active material layer along the winding direction and a second uncoated portion not coated with an active material layer, the second electrode having the first polarity, at least a portion of the second uncoated portion being defined as an electrode tab, and further including a second current collector electrically connected to the second uncoated portion and having at least a portion of its periphery attached to a side wall of the battery housing.

134. 130. The battery of claim 129, wherein the second electrode includes a second active material portion coated with an active material layer along the winding direction and a second uncoated portion not coated with an active material layer, the second electrode having the first polarity, at least a portion of the second uncoated portion being defined as an electrode tab, and further including a second current collector electrically connected to the second uncoated portion and having at least a portion of its periphery attached to a side wall of the battery housing, and wherein an outer diameter of the first current collector is the same as or larger than an outer diameter of the second current collector.

135. 135. The battery of claim 134, wherein the first current collector and the second current collector are welded to the first uncoated portion and the second uncoated portion, respectively, along the radial direction of the electrode assembly to form a weld pattern, and the length of the weld pattern of the first current collector is longer than the length of the weld pattern of the second current collector.

136. 136. The battery of claim 135, wherein the weld pattern of the first current collector and the weld pattern of the second current collector are located at substantially the same distance from the core center of the electrode assembly.

137. 137. A battery as described in any one of claims 133 to 136, wherein the battery housing includes a beading portion pressed inwardly into the inner wall adjacent the open end, and the periphery of the second current collector is electrically connected to the beading portion.

138. 138. The battery of claim 137, wherein the area of the second current collector in electrical contact with the second plain portion is located inside the inner circumferential surface of the beading portion.

139. 139. The battery of claim 137 or 138, comprising: a cap whose periphery is supported by the beading portion and has no polarity; a gasket interposed between the periphery of the cap and the open end of the battery housing; and a crimping portion that extends inside the open end of the battery housing and is bent to wrap around and secure the periphery of the cap together with the gasket, wherein the periphery of the second current collector is interposed and secured between the beading portion and the gasket by the crimping portion.

140. 140. The battery of any one of claims 137 to 139, wherein the periphery of the second current collector is welded to the beading portion.

141. The third portion and optionally the second portion are divided into a plurality of segments that can be bent independently, and the first uncoated portion is divided into a plurality of segments, and the height of the segments is a first height h along one direction parallel to the winding direction. １ ~ N-1th height h Ｎ－１ (N is a height index and is a natural number equal to or greater than 2) Ｎ (h Ｎ－１ 141. The battery of any one of claims 122 to 140, comprising a uniform height section that is maintained uniformly at a constant height (greater than 1 / 2 mm).

142. 142. The battery of claim 141, wherein N is 2 to 30.

143. The height h ｋ (k is a natural number from 1 to N) and the number of segments having a height h ｋ 143. The battery of claim 141 or 142, wherein the plurality of minute segments having the same are arranged in one or more winding turns.

144. Height h ｋ (k is a natural number from 1 to N) The starting radius of the winding turn containing the segment is r ｋ When the core of the electrode assembly is defined as ｋ 144. The battery of any one of claims 141 to 143, wherein the battery is not blocked by a bent portion of the section located at the

145. Height h ｋ (k is a natural number from 1 to N) The starting radius of the winding turn containing the segment is r ｋ , the radius of the core is r ｃ Then, the height of the segment h ｋ is the following formula 2 mm ≦ h ｋ ≦r ｋ -α×r ｃ (α is between 0.90 and 1) 145. The battery of any one of claims 141 to 144, wherein

146. When the radius of the winding turn including the segment based on the core center of the electrode assembly is defined as r and the width of the segment in the winding direction is defined as D(r), D(r) can be calculated by the following equation: 1≦D(r)≦(2×π×r / 360°)×45° 146. The battery of any one of claims 141 to 145, wherein

147. 147. The battery of any one of claims 141 to 146, wherein the height of the plurality of segments gradually or stepwise increases or decreases in width in the winding direction of the segments as the radius r of the winding turn on which the segments are located increases relative to the core center of the electrode assembly.

148. 148. The battery of any one of claims 141 to 147, wherein the height of the plurality of segments gradually or stepwise increases and then gradually or stepwise decreases as the radius r of the winding turn on which the segments are located increases relative to the core center of the electrode assembly, or vice versa.

149. Each of the plurality of segments has a geometric shape in which a width at a bottom is wider than a width at an top, and a bottom interior angle θ of the segment located at a winding turn having a radius r around the core of the electrode assembly falls within an angle range of the following formula: [Equation 2] 142. The battery of claim 141, wherein D is the width of the segment in the winding direction, r is the radius of the winding turn in which the segment is included, H is the height of the segment, and p is the spacing pitch of the segment.

150. 150. The battery of claim 149, wherein the plurality of segments have lower interior angles that increase individually or in groups in a range of 60° to 85° in one direction parallel to the winding direction.

151. In the variable height section and the uniform height section, the maximum height h of the segment ｍａｘ satisfies the following formula, h ｍａｘ ≦W ｆｏｉｌ -W ｓｃｒａｐ，ｍｉｎ -W ｍａｒｇｉｎ，ｍｉｎ -W ｇａｐ W ｆｏｉｌ is the width of the current collector foil before the segments are formed, and W ｓｃｒａｐ，ｍｉｎ is the width corresponding to the minimum cutting scrap margin when cutting the current collector foil to form cut pieces, and W ｍａｒｇｉｎ，ｍｉｎ is the width corresponding to the minimum meandering margin of the separation membrane, and W ｇａｐ 151. The battery of any one of claims 141 to 150, wherein ∇ is a width corresponding to an insulating gap between an end of the second electrode facing the first electrode across the separator and an end of the separator.

152. When the first electrode is a positive electrode, the insulating gap W ｇａｐ 152. The battery of claim 151, wherein is between 0.2 mm and 6 mm.

153. When the first electrode is a negative electrode, the insulating gap W ｇａｐ 152. The battery of claim 151, wherein is between 0.1 mm and 2 mm.

154. The minimum cutting scrap margin W ｓｃｒａｐ，ｍｉｎ 152. The battery of claim 151, wherein is 1.5 mm to 8 mm.

155. The minimum meandering margin W of the separation membrane ｍａｒｇｉｎ，ｍｉｎ 152. The battery of claim 151, wherein is 0 to 1 mm.

156. 152. The battery of claim 151, wherein the minimum cutting scrap margin is 0.

157. 157. A battery as described in any one of claims 151 to 156, wherein the height of the segments arranged in the height variable section increases gradually or stepwise within a range of 2 mm to 10 mm.

158. The battery of any one of claims 122 to 157, wherein the third portion and, optionally, the second portion are divided into a plurality of segments that can be bent independently, and the electrode assembly includes, in sequence along a radial direction based on a cross section along the winding axis direction, a segment-free section where no segments exist, a height-variable section where the height of the segments varies, and a height-uniform section where the height of the segments is uniform, and the plurality of segments are arranged in the height-variable section and the height-uniform section and form a folded surface region as they are folded along the radial direction of the electrode assembly.

159. 159. The battery of claim 158, wherein the first portion is not divided into segments, and the segment-omitted section corresponds to the first portion.

160. A battery as described in claim 158 or 159, wherein, in the radial direction of the electrode assembly, the ratio of the radial length of the segment-omitted section to the radius of the electrode assembly excluding the core is 10% to 40%.

161. A battery as described in any one of claims 158 to 160, wherein in the radial direction of the electrode assembly, the ratio of the radial length of the height variable section to the radial lengths corresponding to the height variable section and the height uniform section is 1% to 50%.

162. A battery as described in any one of claims 158 to 161, wherein the ratio of the length of the electrode area corresponding to the segment-omitted section to the entire length of the first electrode is 1% to 30%.

163. A battery as described in any one of claims 158 to 162, wherein the ratio of the length of the electrode region corresponding to the height-variable section to the overall length of the first electrode is 1% to 40%.

164. A battery as described in any one of claims 158 to 163, wherein the ratio of the length of the electrode region corresponding to the uniform height section to the entire length of the first electrode is 50% to 90%.

165. The battery of claim 141, wherein the plurality of segments form a plurality of segment groups along a direction parallel to the winding direction of the electrode assembly, and the segments belonging to the same segment group have substantially the same width in the winding direction and height in the winding axis direction.

166. The battery of claim 165, wherein the segments belonging to the same segment group have at least one of a width in the winding direction and a height in the winding axis direction that increase stepwise toward one direction parallel to the winding direction of the electrode assembly.

167. The battery of claim 165, comprising a combination of sub-segment groups in which W3 / W2 is smaller than W2 / W1, where W1, W2, and W3 are the winding direction widths for each of three sub-segment groups that are consecutively adjacent in one direction parallel to the winding direction of the electrode assembly.

168. 159. The battery of claim 158, wherein the number of laminations of the segment at a radial position of the folded surface region is defined as the number of laminations of the segment at the corresponding radial position, the number of laminations of the segment being equal from the core side to the outer periphery side, and the folded surface region includes a uniform lamination number section in which the number of laminations of the segment is uniform from the core side to the outer periphery side, and a decreasing lamination number section located adjacent to the uniform lamination number section and in which the number of laminations of the segment decreases with increasing distance from the uniform lamination number section.

169. The battery of claim 168, wherein the uniform stacking number section has 10 or more stacked pieces.

170. The battery of claim 168, wherein the uniform stacking number section has a stacking number of the section pieces of 10 to 35.

171. 171. The battery of any one of claims 168 to 170, wherein a starting radius of the uniform stacking number section relative to the core center of the electrode assembly corresponds to a starting radius of the variable height section.

172. A battery as described in any one of claims 168 to 171, wherein the ratio of the radial length of the uniform stack number section to the radial lengths of the uniform stack number section and the decreasing stack number section is 30% to 85%.

173. The battery of any one of claims 168 to 172, wherein the first electrode is a positive electrode and the stacking thickness of the divided pieces in the uniform stacking number section is 100 μm to 875 μm.

174. The battery of any one of claims 168 to 173, further comprising a current collector welded to the uniform stacking number section so that at least a portion of the uniform stacking number section and the welding region overlap, the first electrode being a positive electrode, and the stacking thickness of the divided piece in the welding region being 100 μm to 875 μm.

175. The battery of any one of claims 168 to 174, wherein the first electrode is a negative electrode and the stacking thickness of the divided pieces in the uniform stacking number section is 50 μm to 700 μm.

176. The battery of any one of claims 168 to 175, further comprising a current collector welded to the uniform stacking number section so that at least a portion of the uniform stacking number section and the welding region overlap, the first electrode being a negative electrode, and the stacking thickness of the divided piece in the welding region is 50 μm to 700 μm.

177. The battery of claim 122, wherein the third portion and, optionally, the second portion are divided into a plurality of segments that can be bent independently, a cutting groove is interposed between adjacent segments along the winding direction, and a lower portion of the cutting groove includes a bottom and rounded portions that connect both ends of the bottom to the side edges of the segments on both sides of the cutting groove.

178. 178. The battery of claim 177, wherein the radius of curvature of the rounded portion is greater than 0 and less than or equal to 0.1 mm.

179. The battery of claim 177 or 178, wherein the radius of curvature of the rounded portion is 0.01 mm to 0.05 mm.

180. 178. The battery of claim 177, wherein the bottom is flat.

181. A battery as described in any one of claims 177 to 179, wherein a separation pitch defined as the distance between two points where a line extended from the side edges of the two segments located on both sides of the cutting groove intersects with a line extended from the bottom of the cutting groove is 0.05 mm to 1.00 mm.

182. The battery of any one of claims 177 to 181, wherein the plurality of segments are made of aluminum foil, and a spacing pitch defined as the distance between two points where a line extending from the side edges of two segments located on either side of the cutting groove intersects with a line extending from the lower end of the cutting groove is 0.5 mm to 1.00 mm.

183. 183. The battery of any one of claims 177 to 182, wherein the bottom of the cutting groove is spaced a fixed distance from the active material layer.

184. The battery of claim 183, wherein the distance between the bottom of the cutting groove and the active material layer is 0.2 mm to 4 mm.

185. A battery as described in any one of claims 177 to 184, wherein the plurality of sections are bent radially of the electrode assembly in a section of 0 to 1 mm above the bottom of the cutting groove.

186. A battery as described in any one of claims 177 to 185, wherein an insulating coating layer is formed at the boundary between the active material layer and an uncoated area present in the section where the bottom of the cutting groove and the active material layer are separated.

187. 187. The battery of claim 186, wherein the insulating coating layer comprises a polymeric resin and an inorganic filler dispersed in the polymeric resin.

188. 188. The battery of claim 186 or 187, wherein the insulating coating layer is formed to cover the boundary portion between the active material layer and the first uncoated portion along the winding direction.

189. The battery of claim 188, wherein the insulating coating layer is formed so as to cover the boundary portion between the active material layer and the first uncoated portion with a width of 0.3 mm to 5 mm along the winding axis.

190. The battery of any one of claims 186 to 189, wherein the end of the insulating coating layer is located in a range of -2 mm to 2 mm along the winding axis direction relative to the end of the separator.

191. 191. The battery of claim 190, wherein the insulating coating layer is exposed to the outside of the separator.

192. 192. The battery of any one of claims 186 to 191, wherein the lower end of the cutting groove and the insulating coating layer are spaced apart by a distance of 0.5 mm to 2 mm.

193. The battery of claim 192, wherein the end of the insulating coating layer in the winding axis direction is located within a range of -2 mm to +2 mm relative to the lower end of the cutting groove.

194. 169. The battery of claim 168, further comprising a current collector welded to the folded surface region, wherein the welded region of the current collector overlaps the stack number uniform section by at least 50% in the radial direction of the electrode assembly.

195. 195. The battery of claim 194, wherein, in the radial direction of the electrode assembly, the welding region of the current collector that does not overlap with the uniform lamination number section overlaps with the reduced lamination number section.

196. A battery as described in claim 194 or 195, wherein the peripheral edge of the current collector is welded to the folded surface area while being positioned on the folded surface area so as to cover the end of the folded portion of the radially outermost outer section of the electrode assembly.

197. The welding strength of the welded area of the current collector is 2 kgf / cm ２ The battery of any one of claims 194 to 196.

198. The welding strength of the welded area of the current collector is 4 kgf / cm ２ 197. The battery of any one of claims 194 to 196.

199. the first uncoated portion is made of metal foil, The metal foil has an elongation ratio of 1.5% to 3.0% and a tensile strength of 25 kgf / mm ２ ~35 kgf / mm ２ 123. The battery of claim 122, wherein:

200. 200. The battery of claim 199, wherein the metal foil is aluminum foil.

201. 201. The battery of claim 199 or 200, wherein the camber length of the first electrode is less than 20 mm.

202. The battery of claim 122, wherein the ratio of the length of the short side parallel to the winding axis direction to the length of the long side parallel to the winding direction of the first active material part is 1% to 4%.

203. an electrode assembly in which a core and an outer circumferential surface are defined by winding a first electrode, a second electrode, and a separator interposed therebetween around a winding shaft, the first electrode including a first active material portion coated with an active material layer along the winding direction and a first uncoated portion not coated with the active material layer, the first uncoated portion including a section divided into a plurality of segments that can be independently bent from a core side toward an outer circumferential side of the electrode assembly, the plurality of segments being bent along a radial direction of the electrode assembly to form a bent surface region, the bent surface region including a uniform stack number section in which the number of stacked segments is 10 or more along the radial direction, and a decreasing stack number section located adjacent to the uniform stack number section, the number of stacked segments decreasing as the distance from the uniform stack number section increases; a battery housing including an open end and a bottom portion facing the open end, the battery housing accommodating the electrode assembly in a space between the open end and the bottom, the battery housing being electrically connected to one of the first electrode and the second electrode and having a first polarity; a seal that seals the open end of the battery housing; a terminal electrically connected to the other of the first electrode and the second electrode, the terminal having a surface exposed to the outside and a second polarity.

204. an electrode assembly in which a positive electrode, a negative electrode, and a separator interposed therebetween are wound around a winding shaft to define a core and an outer circumferential surface, the positive electrode including a first active material portion coated with an active material layer along the winding direction and a first uncoated portion not coated with the active material layer, at least a portion of the first uncoated portion itself being used as an electrode tab, the first uncoated portion including a plurality of segments that can be independently bent from a core side toward an outer circumferential side of the electrode assembly, the plurality of segments being stacked in multiple layers while being folded along a radial direction of the electrode assembly to form a folded surface region, the folded surface region including a uniform stack number section in which the number of stacked segments is uniform along the radial direction, and a decreasing stack number section located adjacent to the uniform stack number section and in which the number of stacked segments decreases with increasing distance from the uniform stack number section, the stack thickness of the segments in the uniform stack number section being 100 μm to 875 μm; a battery housing including an open end and a bottom portion facing the open end, the battery housing containing the electrode assembly in a space between the open end and the bottom, the battery housing being electrically connected to one of the positive electrode and the negative electrode and having a first polarity; a seal that seals the open end of the battery housing; a terminal electrically connected to the other of the positive electrode and the negative electrode, the terminal having a surface exposed to the outside and a second polarity.

205. The battery of claim 204, wherein the electrode assembly further includes a current collector welded to the uniform stacking number section so that the uniform stacking number section and the welding area overlap, and the stacking thickness of the divided piece in the welding area is 100 μm to 875 μm.

206. an electrode assembly in which a positive electrode, a negative electrode, and a separator interposed therebetween are wound around a winding shaft to define a core and an outer circumferential surface, the negative electrode including a first active material portion coated with an active material layer along the winding direction and a first uncoated portion not coated with the active material layer, at least a portion of the first uncoated portion itself being used as an electrode tab, the first uncoated portion including a plurality of segments that can be independently bent from a core side toward an outer circumferential side of the electrode assembly, the plurality of segments being stacked in multiple layers while being folded along a radial direction of the electrode assembly to form a folded surface region, the folded surface region including a uniform stack number section in which the number of stacked segments is uniform along the radial direction, and a decreasing stack number section located adjacent to the uniform stack number section and in which the number of stacked segments decreases with increasing distance from the uniform stack number section, the stack thickness of the segments in the uniform stack number section being 50 μm to 700 μm; a battery housing including an open end and a bottom portion facing the open end, the battery housing containing the electrode assembly in a space between the open end and the bottom, the battery housing being electrically connected to one of the positive electrode and the negative electrode and having a first polarity; a seal that seals the open end of the battery housing; a terminal electrically connected to the other of the positive electrode and the negative electrode, the terminal having a surface exposed to the outside and a second polarity.

207. The battery of claim 206, wherein the electrode assembly further includes a current collector welded to the uniform lamination number section so that the uniform lamination number section and the welding region overlap, and the lamination thickness of the divided piece in the welding region is 50 μm to 700 μm.

208. A battery pack comprising a plurality of batteries according to any one of claims 122 to 207.

209. 209. The battery pack of claim 208, wherein the battery has a height-to-diameter ratio of greater than 0.

4.

210. 210. The battery pack of claim 209, wherein the battery form factor is 46110, 4875, 48110, 4880 or 4680.

211. 209. The battery pack of claim 208, wherein the resistance of the battery is 4 mΩ or less.

212. 209. A battery pack as described in claim 208, wherein the plurality of batteries are arranged in a predetermined number of rows, and the terminals of each battery and the outer surface of the bottom of the battery housing are arranged facing upward.

213. 213. The battery pack of claim 212, comprising a plurality of bus bars connecting a plurality of batteries in series and parallel, the plurality of bus bars being disposed on top of the plurality of batteries, each of the plurality of bus bars comprising: a body portion extending between terminals of adjacent batteries; a plurality of first bus bar terminals extending to one side of the body portion and electrically connecting to the terminals of the batteries located on the one side; and a plurality of second bus bar terminals extending to the other side of the body portion and electrically connecting to an outer surface of the bottom of the cell housing of the batteries located on the other side.

214. A motor vehicle comprising a battery pack according to any one of claims 208 to 213.

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