Electrode assemblies, batteries, battery packs containing them, and automobiles

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 an automobile containing the same.

[0002] This application is related to 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 19, 2021, Korean Patent Application No. 10-2021-0024424 filed on February 23, 2021, and March 2021. Korean Patent Application No. 10-2021-0030300 filed on the 8th of the month, 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. Korean Patent Application No. 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 1, 2021, Korean Patent Application No. 10-2021-0137001 filed on October 14, 2021, Korean Patent Application No. 10-2021-0137001 filed on October 15, 2021 Korean Patent Application No. 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, 202 Priority is claimed based on Korean Patent Application No. 10-2021-0194612 filed on December 31, 2019, 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 all contents disclosed in the specifications and drawings of said applications are incorporated into this application. [Background technology]

[0003] Rechargeable batteries, which offer high applicability across different product groups and possess electrical characteristics such as high energy density, are universally applied not only to portable devices but also to electric vehicles (EVs) and hybrid electric vehicles (HEVs) powered by electric drive sources.

[0004] Such secondary batteries are attracting attention not only for their primary benefit of dramatically reducing the use of fossil fuels, but also because they are environmentally friendly in that they produce no by-products from energy use, making them a promising new energy source for improving energy efficiency.

[0005] Currently, rechargeable 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 a single rechargeable battery, i.e., a single battery, is approximately 2.5V to 4.5V. Therefore, when a higher output voltage is required, multiple batteries are connected in series to form a battery pack. Alternatively, multiple batteries may be connected in parallel to form a battery pack, depending on the required charge and discharge capacity. Thus, the number of batteries included in the battery pack and the electrical connection configuration can be set in various ways depending on the required output voltage and / or charge and discharge capacity.

[0006] On the other hand, known types of rechargeable batteries include cylindrical, prismatic, and pouch-type batteries. In the case of a cylindrical battery, an insulating separator membrane is interposed between the positive and negative electrodes, and this is wound up to form a jelly-roll type electrode assembly, which is then inserted into the battery housing to constitute the battery. The battery housing is called a battery can in this industry. Strip-shaped electrode tabs are connected to the blank portions of the positive and negative electrodes, and these electrode tabs electrically connect the electrode assembly to the electrode terminals exposed to the outside. For reference, the positive electrode terminal is the cap of the sealing body that seals the opening of the battery housing, and the negative electrode terminal is the battery housing. However, with conventional cylindrical batteries having such a structure, current is concentrated in the strip-shaped electrode tabs connected to the blank portion of the positive electrode and / or the blank portion of the negative electrode, resulting in high resistance, high heat generation, and poor current collection efficiency.

[0007] In small cylindrical batteries with form factors such as 1865 (diameter: 18mm, height: 65mm) and 2170 (diameter: 21mm, height: 70mm), resistance and heat generation are not significant problems. However, when increasing the form factor of cylindrical batteries for application in electric vehicles, a problem can arise where the cylindrical battery catches fire during the rapid charging process due to the large amount of heat generated around the electrode tabs.

[0008] To solve these problems, a cylindrical battery (a so-called tab-less cylindrical battery) has been proposed in which a blank positive electrode section and a blank negative electrode section are located at the upper and lower ends of a jelly roll-type electrode assembly, respectively, and a current collector is welded to these blank sections to improve current collection efficiency.

[0009] Figures 1 to 3 illustrate the manufacturing process of a tablet cylindrical battery. Figure 1 shows the structure of the electrodes, Figure 2 shows the electrode winding process, and Figure 3 shows the process of welding the current collector to the bent surface area of ​​the plain section.

[0010] Referring to Figures 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-like current collector 20, and include a plain portion 22 on one of the longer sides along the winding direction X. The longer side refers to the side that is parallel to the x-axis direction and has a relatively longer length.

[0011] Electrode assembly A is manufactured by sequentially stacking the positive electrode 10 and the negative electrode 11 together with two separation membranes 12 as shown in Figure 2, and then winding them in one direction (X-axis direction). At this time, the plain portion of the positive electrode 10 and the plain portion of the negative electrode 11 are positioned in opposite directions to each other.

[0012] After the winding process, the plain portion 10a of the positive electrode 10 and the plain portion 11a of the negative electrode 11 are bent towards the core. Subsequently, the current collectors 30 and 31 are welded and joined to the plain portions 10a and 11a, respectively.

[0013] The blank positive electrode section 10a and the blank negative electrode section 11a are not connected to separate electrode tabs, and the current collectors 30 and 31 are connected to external electrode terminals. As a result, the current path is formed with a large cross-sectional area along the winding axis direction of the electrode assembly A (see arrow), which has the advantage of reducing the battery's resistance. This is because resistance is inversely proportional to the cross-sectional area of ​​the path through which the current flows.

[0014] In a tablet cylindrical battery, in order to improve the welding characteristics between the plain sections 10a and 11a and the current collectors 30 and 31, strong pressure must be applied to the welding area of ​​the plain sections 10a and 11a to bend them as flat as possible.

[0015] However, when the welded areas of the plain sections 10a and 11a are bent, the patterns of the plain sections 10a and 11a may be irregularly distorted and deformed. In this case, the deformed parts may come into contact with electrodes of opposite polarity, causing an internal short circuit, or it may induce fine cracks in the plain sections 10a and 11a. Also, as the plain section 32 adjacent to the core of electrode assembly A is bent, it may block all or a substantial portion of the cavity 33 in the core of electrode assembly A. In this case, problems arise in the electrolyte injection process. That is, the cavity 33 in the core of electrode assembly A is used as a passage for electrolyte injection. However, if this passage is blocked, it becomes difficult to inject the electrolyte. Also, when the electrolyte injector is inserted into the cavity 33, it may interfere with the plain section 32 near the core, causing the plain section 32 to tear.

[0016] Furthermore, the bent portions of the plain sections 10a and 11a to which the current collectors 30 and 31 are welded overlap multiple times, and there should be no empty spaces (gaps). This ensures sufficient welding strength and prevents problems such as the laser penetrating the inside of the electrode assembly A and melting the separation membrane or active material when using advanced technologies such as laser welding.

[0017] On the other hand, in conventional tablet cylindrical batteries, a blank positive electrode portion 10a is formed on the upper part of the electrode assembly A. Therefore, when the outer peripheral surface of the upper end of the battery housing is pushed inward to form the beading portion, the upper edge region 34 of the electrode assembly A is compressed by the battery housing. Such compression causes partial deformation of the electrode assembly A, and at this time, the separator membrane 12 may rupture, potentially causing an internal short circuit. If a short circuit occurs inside the battery, it can cause the battery to overheat or explode. [Overview of the project] [Problems that the invention aims to solve]

[0018] The present invention was conceived against the background of the prior art described above, and aims to provide an electrode assembly having an improved plain section structure that can alleviate the stress applied to the plain section when the plain section exposed at both ends of the electrode assembly is bent.

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

[0020] Furthermore, another object of the present invention is to provide an electrode assembly that includes a structure capable of preventing the upper edge of the electrode assembly from coming into contact with the inner surface of the battery housing when the upper end of the battery housing is beaded.

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

[0022] Furthermore, the present invention aims to provide an electrode assembly with improved energy density and reduced resistance by applying a structure in which a current collector is welded over a wide area to a bent surface region formed by bending a segment.

[0023] Furthermore, another object of the present invention is to provide a battery including terminals and current collectors that have been improved in design for electrical wiring at the top.

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

[0025] The technical problems that this invention aims to solve are not limited to those described above, and other problems will be clearly understood by an ordinary person from the following description of the invention. [Means for solving the problem]

[0026] To achieve the above objectives, an electrode assembly according to one aspect of the present invention is an electrode assembly in which a core and an outer surface are defined by winding a first electrode, a second electrode, and a separation membrane interposed between them 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 plain portion not coated with an active material layer, at least a part of the first plain portion is defined as an electrode tab, and the first plain portion includes a first portion adjacent to the core of the electrode assembly, a second portion adjacent to the outer surface of the electrode assembly, and a third portion between the first and second portions, wherein in the winding axis direction, the first or second portion is lower in height than the third portion.

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

[0028] In other embodiments, the second and third portions may be defined as electrode tabs when bent along the radial direction of the electrode assembly.

[0029] Preferably, at least a portion of the third portion can be divided into a plurality of independently foldable sections.

[0030] Preferably, each of the multiple segments may have the form of a geometric figure formed by connecting one or more straight lines, one or more curves, or a combination thereof.

[0031] For example, each of the multiple segments may have a lower width that is wider than its upper width.

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

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

[0034] As yet another example, each of the multiple segments may decrease in width from bottom to top before increasing.

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

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

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

[0038] Preferably, each of the multiple segments may have sides that are straight, curved, or a combination of these.

[0039] For example, each of the multiple sections may have sides that are convex outward or convex inward.

[0040] As another example, each of the multiple sections may have a rounded shape at the top corner.

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

[0042] Preferably, the subsections may increase gradually or stepwise individually, in groups, or in units of multiple groups, in one direction parallel to the winding direction, with the lower interior angle being parallel to the winding direction.

[0043] In one embodiment, the subsections may be individually, in groups, or in units of multiple groups, gradually or stepwise, with the lower interior angle increasing in a range of 60° to 85° in one direction parallel to the winding direction.

[0044] In other forms, the lower interior angle of each segment belonging to a segment group may be even larger than the lower interior angle of each segment belonging to a segment group located closer to the core.

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

[0046]

number

[0047] In other forms, each of the multiple segments may have sides that are straight, curved, or a combination thereof.

[0048] In other forms, each of the multiple sections may have sides that are convex outward or convex inward.

[0049] In other forms, each of the multiple sections may have a rounded upper corner.

[0050] Preferably, cutting grooves are interposed between adjacent segments along the winding direction, and the lower part of the cutting groove may include a bottom and rounded portions connecting both ends of the bottom with the sides of the segments 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 less than or equal to 0.1 mm, more preferably 0.01 mm to 0.05 mm.

[0052] In other forms, the bottom may be flattened.

[0053] In yet another embodiment, the separation pitch, defined by the distance between two points where lines extending from the sides of the two segment pieces located on either side of the cutting groove intersect with a line extending from the bottom of the cutting groove, may be 0.05 mm to 1.00 mm.

[0054] In yet another embodiment, the plurality of segments are made of aluminum foil, and the spacing pitch, defined by the distance between two points where lines extending from the sides of two segments located on either side of the cutting groove intersect 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 separation pitch of the plurality of segments may vary along one direction parallel to the winding direction, defined by the distance between two points where lines extending from the sides of two segments located on either side of the cutting groove intersect with a line extending from the bottom of the cutting groove.

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

[0057] In yet another embodiment, the bottom of the cutting groove may be separated from the active material layer by a certain distance.

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

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

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

[0061] In yet another embodiment, each of the plurality of subsections may have an inscribed angle of 45° or less in the arc formed by the lower end of the subsection with respect to the core center of the electrode assembly.

[0062] Preferably, when the radius of the winding turn containing the segment is defined as r with respect to the core center of the electrode assembly, and the width of the segment in the winding direction is defined as D(r), then 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 subsections may have a winding width D(r) that increases gradually or in steps as the radius r of the winding turn in which the subsection is located increases with respect to the core center of the electrode assembly, or vice versa.

[0064] In yet another embodiment, each of the plurality of subsections may have a winding width D(r) that gradually or stepwise increases and then gradually or stepwise decreases, or vice versa, as the radius r of the winding turn in which the subsection is located increases with respect to the core center of the electrode assembly.

[0065] In other embodiments, each of the plurality of segments may have substantially the same inscribed angle with respect to the core center of the electrode assembly.

[0066] In yet another embodiment, the plurality of segments may increase in width in the winding direction along one direction parallel to the winding direction of the electrode assembly by a substantially the same or different ratio.

[0067] Preferably, each of the plurality of subsections may have a subsection width that increases gradually or stepwise within the range of 1 mm to 11 mm as the radius r of the winding turn in which the subsection is located increases with respect to the core center of the electrode assembly.

[0068] In yet another embodiment, at least a portion of the third portion may have a height in the winding axis direction that changes gradually or in steps in one direction parallel to the winding direction.

[0069] Preferably, in at least a portion of the third portion, the height in the winding axis direction may be gradually or stepwise increased 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 of different heights along one direction parallel to the winding direction, and the height of the plain portion in the plurality of regions may increase in steps along one direction parallel to the winding direction.

[0072] In one embodiment, the first plain section has a segment height of first height h1 to N-1 height h along one direction parallel to the winding direction. N-1 A height-variable interval that changes stepwise up to (where N is the height index and is a natural number greater than or equal to 2), and a height h of N. N (h N-1 It may include a uniform height section that is maintained uniformly (greater than).

[0073] Preferably, N can be 2 to 30.

[0074] In one form, the height h k (where k is a natural number from 1 to N) is plural in number for the segmented pieces, and the plurality of segmented pieces having the height h k can be arranged in one or more winding turns.

[0075] In another form, when defining the starting radius r of the winding turn containing the segmented piece having the height h k (where k is a natural number from 1 to N), more than 90% of the diameter of the core of the electrode assembly is not blocked by the bent portion of the segmented piece located at the r k . k

[0076] In yet another form, when the starting radius r of the winding turn containing the segmented piece having the height h k (where k is a natural number from 1 to N), and the radius of the core is r k , the height h c of the segmented piece may satisfy the following formula. k The height h satisfies 2 mm ≤ h k ≤ r k - α × r c (where α is from 0.90 to 1).

[0077] Preferably, the electrode assembly includes, based on the cross-section along the winding axis direction, in the radial direction, in sequence, a segment omission section where there are no segmented pieces, a height variable section where the height of the segmented pieces changes, and a height uniform section where the height of the segmented pieces is uniform. The plurality of segmented pieces are arranged in the height variable section and the height uniform section, and can form a bent surface region while being bent along the radial direction of the electrode assembly.

[0078] In one form, the first part is not divided into segmented pieces, and the segment omission section may correspond to the first part.

[0079] In another form, the third part is divided into a plurality of segmented pieces that can be independently bent, and the height variable section and the height uniform section may correspond to the third part.

[0080] In yet another embodiment, the second and third parts are divided into a plurality of independently foldable segments, and the height-variable section and the height-uniform section may correspond to the second and third parts.

[0081] Preferably, in the height-variable section and the height-uniform section, the maximum height h of the segment is max The following equation may be satisfied. h max ≤W foil -W scrap,min -W margin,min -W gap (W foil W is the width of the current collector foil before the segment is formed; scrap,min When cutting the current collector foil to form a segment, W is the width corresponding to the minimum cutting scrap margin; margin,min W is the minimum meandering margin of the separation membrane; gap (This corresponds to the width of the insulating gap between the end of the second electrode, which faces the first electrode via the separation membrane, and the end of the separation membrane.)

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

[0083] Preferably, the insulation gap W gap This can be 0.1 mm to 2 mm when the first electrode is the negative electrode.

[0084] Preferably, the minimum cutting scrap margin W scrap,min This can range from 1.5 mm to 8 mm. The minimum cutting scrap margin W depends on the method of cutting the section. scrap,min It can be 0.

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

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

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

[0088] In other embodiments, the ratio of the radial length of the height-variable section to the radial length corresponding to the height-variable section and the height-uniform section in the radial direction of the electrode assembly may be 1% to 50%.

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

[0090] In yet another embodiment, the ratio of the length of the electrode region corresponding to the height-adjustable section to the total length of the first electrode may be 1% to 40%.

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

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

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

[0094] In other embodiments, the plurality of subsections form a plurality of subsection groups along one direction parallel to the winding direction of the electrode assembly, and subsections belonging to the same subsection group may be substantially identical to one selected from the width in the winding direction, the height in the winding direction axis, and the lower interior angle of the subsection.

[0095] In other forms, multiple subsection groups may have different subsection shapes, either on a group basis or between two or more groups.

[0096] In other forms, multiple subsection groups may have different spacing between subsections, either on a group-by-group basis or between two or more groups.

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

[0098] In yet another embodiment, segments belonging to the same segment group may have at least one of their width in the winding direction and 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 widths in the winding direction for three consecutively adjacent segment groups in a direction parallel to the winding direction of the electrode assembly are W1, W2, and W3, respectively, the embodiment may include a combination of segment groups in which W3 / W2 is smaller than W2 / W1.

[0100] In other embodiments, the first portion is not divided into segments, and the first portion is not bent along the radial direction of the electrode assembly.

[0101] In other embodiments, 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 the boundary between the plain area in the section where the bottom of the cutting groove and the active material layer are separated, and the active material layer.

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

[0104] In other embodiments, the insulating coating layer may be formed to cover the boundary between the active material layer and the first plain portion along the winding direction.

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

[0106] In yet another embodiment, the edges of the insulating coating layer may be located in the range of -2 mm to 2 mm along the winding axis with respect to the edges of the separation film.

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

[0108] Preferably, the lower end of the cutting groove and the insulating coating layer can be separated 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 with respect to the lower end of the cutting groove.

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

[0112] As an example, the separation 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 along one direction parallel to the winding direction.

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

[0114] In yet another embodiment, the third portion and optionally the second portion are divided into a plurality of independently bendable segments, and the electrode assembly may include a bendable surface region formed as the plurality of segments are bent along the radial direction of the electrode assembly.

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

[0116] In one embodiment, the radial lengths of the uniform number of layers section and the decreasing number of layers section, with respect to the core center of the electrode assembly, may correspond to the radial length of the radial section in which the winding turns containing the plurality of subsections are located.

[0117] In other embodiments, the electrode assembly sequentially includes a section without segmentation segments, a height-variable section where the height of the segmentation segments changes, and a height-uniform section where the height of the segmentation segments is uniform, along the radial direction, and the radius at which the uniform stacking section begins with respect 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 layers of the segment in the uniform layering interval may be 10 to 35.

[0119] In one embodiment, the first electrode is a positive electrode, and the stacking thickness of the segment in the uniform stacking section can be 100 μm to 875 μm.

[0120] In other embodiments, the first electrode is a negative electrode, and the stacking thickness of the segment in the uniform stacking section may be 50 μm to 700 μm.

[0121] In other embodiments, the ratio of the radial length of the uniform stacking section to the radial length of the uniform stacking section and the decreasing stacking section may be 30% to 85%.

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

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

[0124] In other embodiments, the periphery of the current collector can be welded to the bent surface region while positioned on the bent surface region such that it covers the end of the bent portion of the outermost segment of the electrode assembly in the radial direction.

[0125] Preferably, the welding strength for the welding area of ​​the current collector is 2 kgf / cm². 2 It could be any of the above.

[0126] More preferably, the welding strength for the welding area of ​​the current collector is 4 kgf / cm². 2 It could be any of the above.

[0127] In yet another embodiment, the first plain portion is made of metal foil, the metal foil having an elongation ratio of 1.5% to 3.0% and a tensile strength of 25 kgf / mm². 2 ~35 kgf / mm 2 It is possible.

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

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

[0130] Preferably, in the first active material portion, 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 portion is preferably 1.0% to 4.0%.

[0131] In yet another embodiment, the height of the second portion may decrease in stages or gradually from the core side to the outer circumference side of the electrode assembly.

[0132] In yet another embodiment, the second and third parts are divided into a plurality of independently foldable segments, the segments included in the second part may have at least one of the width in the winding direction and the height in the winding direction greater than the segments included in the third part.

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

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

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

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

[0137] Preferably, the plurality of segments are arranged radially with respect to the core center of the electrode assembly, and the segments omitted may also be arranged radially with respect to the center of the electrode assembly.

[0138] Preferably, the plurality of segments may be located within a predetermined circular angle range with respect to 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 circumferentially with respect to the core center of the electrode assembly.

[0140] Preferably, the inscribed angle of the sector region may be 20° or greater.

[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 plain portion not coated with an active material layer, where at least a portion of the second plain portion is defined as an electrode tab, and the second plain portion includes a section divided into a plurality of independently bendable segments, the plurality of segments being bendable along the radial direction of the electrode assembly to form a bendable surface region.

[0142] To achieve the above objectives, an electrode assembly according to another aspect of the present invention is an electrode assembly in which a core and an outer surface are defined by winding a first electrode, a second electrode, and a separation membrane interposed between them 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 plain portion not coated with an active material layer, the first plain portion includes a section divided into a plurality of segments that can be independently bent from the core side to the outer periphery side of the electrode assembly, the plurality of segments bent along the radial direction of the electrode assembly to form a bent surface region, the bent surface region includes a uniform stacking section in which the number of stacked segments is 10 or more along the radial direction, and a decreasing stacking section located adjacent to the uniform stacking section, where the number of stacked segments decreases as it moves further away from the uniform stacking section.

[0143] To achieve the above objectives, an electrode assembly according to yet another aspect of the present invention is an electrode assembly in which a core and an outer surface are defined by winding a positive electrode, a negative electrode and a separation membrane interposed between them around a winding shaft, wherein the positive electrode includes a first active material portion coated with an active material layer along the winding direction and a first plain portion not coated with an active material layer, at least a portion of the first plain portion is used as an electrode tab, the first plain portion includes a plurality of segmental sections that can be independently bent from the core side to the outer surface side of the electrode assembly, the plurality of segmental sections are stacked in multiple layers while being bent along the radial direction of the electrode assembly to form a bent surface region, the bent surface region includes a uniform stacking section in which the number of stacked segmental sections is uniform along the radial direction, and a decreasing stacking section located adjacent to the uniform stacking section, where the number of stacked segmental sections decreases as it moves away from the uniform stacking section, and the stacking thickness of the segmental sections in the uniform stacking section may be 100 μm to 875 μm.

[0144] Preferably, the electrode assembly may further include a current collector welded to the uniform layer number section such that the uniform layer number section and at least a portion of the welded area overlap. The layer thickness of the segment in the welded area may be 100 μm to 875 μm.

[0145] To achieve the above objectives, an electrode assembly according to yet another aspect of the present invention is an electrode assembly in which a core and an outer surface are defined by winding a positive electrode, a negative electrode and a separation membrane interposed between them around a winding shaft, wherein the negative electrode includes a first active material portion coated with an active material layer along the winding direction and a first plain portion not coated with an active material layer, at least a portion of the first plain portion is used as an electrode tab, the first plain portion includes a plurality of segmental sections that can be independently bent from the core side to the outer surface side of the electrode assembly, the plurality of segmental sections are stacked in multiple layers while being bent along the radial direction of the electrode assembly to form a bent surface region, the bent surface region includes a uniform stacking section in which the number of stacked segmental sections is uniform along the radial direction, and a decreasing stacking section located adjacent to the uniform stacking section, where the number of stacked segmental sections decreases as it moves away from the uniform stacking section, and the stacking thickness of the segmental sections in the uniform stacking section may be 50 μm to 700 μm.

[0146] Preferably, the electrode assembly may further include a current collector welded to the uniform layer number section such that the uniform layer number section and at least a portion of the welded area overlap. The layer thickness of the segment in the welded area may be 50 μm to 700 μm.

[0147] To achieve the above objectives, a battery according to one aspect of the present invention is an electrode assembly in which a core and an outer surface are defined by winding a first electrode, a second electrode and a separator membrane interposed between them 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 blank portion not coated with an active material layer, at least a portion of the first blank portion is defined as an electrode tab, and the first blank portion includes a first portion adjacent to the core of the electrode assembly, a second portion adjacent to the outer surface of the electrode assembly, and The battery housing includes an electrode assembly having a first or second portion in the winding axis direction, wherein the first or second portion is lower in height than the third portion, and includes an open end and a bottom opposite to it, housing the electrode assembly in the space between the open end and the bottom, and electrically connected to one of the first or second electrodes to have a first polarity, a seal that seals the open end of the battery housing, and a terminal electrically connected to the other of the first or second electrode, with its surface exposed to the outside to have 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 includes a beading portion that is pushed inward in a region 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 can be separated by a predetermined distance.

[0149] Preferably, 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 can satisfy the relation D1 ≤ D2.

[0150] In other embodiments, the battery may further include a current collector electrically connected to the third portion, and an insulator covering the current collector, with its periphery interposed and fixed between the inner 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 surface of the beading portion, and the diameter of the current collector may be the same as or larger than the outermost diameter of the third portion.

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

[0153] In yet another embodiment, 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 inward into the battery housing and is bent to wrap around and secure the periphery of the cap together with the gasket, wherein 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 blank portion, and the terminal may be a rivet terminal having the second polarity, electrically connected to the first current collector, and insulatedly mounted in a through hole formed in the bottom of the battery housing.

[0155] In yet another embodiment, the battery may further include 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.

[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 includes a flat portion at its lower end, the insulator includes an opening that exposes the flat portion, and the flat portion can 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 blank portion not coated with an active material layer, the second electrode has the first polarity, and at least a portion of the second blank portion may be defined as an electrode tab. The battery may further include a second current collector electrically connected to the second blank portion and having at least a portion of its periphery coupled to the side wall 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 blank portion not coated with an active material layer, the second electrode has the first polarity, and at least a portion of the second blank portion may be defined as an electrode tab. The battery may further include a second current collector electrically connected to the second blank portion and having at least a portion of its periphery coupled to the side wall of the battery housing. Preferably, the first current collector may have the same outer diameter as or be larger than that of the second current collector.

[0160] Preferably, the first current collector and the second current collector are welded to the first blank portion and the second blank portion of the electrode assembly along the radial direction to form a weld pattern, and the length of the weld pattern of the first current collector may be even 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 located at substantially the same distance from the core center of the electrode assembly.

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

[0163] Preferably, the region in which the second current collector electrically contacts the second plain portion may be located inside the inner circumferential surface of the beading portion.

[0164] In yet another embodiment, the battery may include a cap whose periphery is supported by the beading portion and which is nonpolar; a gasket interposed between the periphery of the cap and the open end of the battery housing; and a crimping portion that extends inward from the open end of the battery housing, is bent, and wraps around and secures 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 can be welded to the beading portion.

[0166] To achieve the above objectives, a battery according to another aspect of the present invention is an electrode assembly in which a core and an outer surface are defined by winding a first electrode, a second electrode and a separator membrane interposed between them 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 plain portion not coated with an active material layer, the first plain portion includes a section divided into a plurality of segments that can be independently bent from the core side to the outer surface side of the electrode assembly, the plurality of segments being bent along the radial direction of the electrode assembly to form a bendable surface region, and the bendable surface region The battery housing includes an electrode assembly having a first polarity, electrically connected to one of the first and second electrodes, and a sealing body that seals the open end of the battery housing, and a terminal that has a second polarity, electrically connected to the other of the first and second electrodes, and whose surface is exposed to the outside.

[0167] To achieve the above objectives, a battery according to yet another aspect of the present invention is an electrode assembly in which a core and an outer surface are defined by winding a positive electrode, a negative electrode and a separator membrane interposed between them around a winding shaft, wherein the positive electrode includes a first active material portion coated with an active material layer along the winding direction and a first blank portion not coated with an active material layer, at least a portion of the first blank portion is used as an electrode tab, the first blank portion includes a plurality of segments that can be independently bent from the core side to the outer surface side of the electrode assembly, the plurality of segments are stacked in multiple layers while being bent along the radial direction of the electrode assembly to form a bendable surface region, and the bendable surface The surface region includes an electrode assembly having a uniform stacking section along the radial direction in which the number of stacked segments is uniform, and a decreasing stacking section located adjacent to the uniform stacking section, where the number of stacked segments decreases as it moves away from the uniform stacking section, and the stacking thickness of the segments in the uniform stacking section is 100 μm to 875 μm; a battery housing having an open end and a bottom opposite to it, housing the electrode assembly in the space between the open end and the bottom, and electrically connected to one of the positive electrode and the negative electrode to have a first polarity; a seal that seals the open end of the battery housing; and a terminal electrically connected to the other of the positive electrode and the negative electrode, with its surface exposed to the outside to have a second polarity.

[0168] Preferably, the battery according to the present invention may further include a current collector welded to the uniform layer number section such that the uniform layer number section and the welded area overlap. The layer thickness of the segment in the welded area may be 100 μm to 875 μm.

[0169] To achieve the above objectives, a battery according to yet another aspect of the present invention is an electrode assembly in which a core and an outer surface are defined by winding a positive electrode, a negative electrode and a separator membrane interposed between them around a winding shaft, wherein the negative electrode includes a first active material portion coated with an active material layer along the winding direction and a first plain portion not coated with an active material layer, at least a portion of the first plain portion is used as an electrode tab, the first plain portion includes a plurality of segments that can be independently bent from the core side to the outer surface side of the electrode assembly, the plurality of segments are stacked in multiple layers while being bent along the radial direction of the electrode assembly to form a bendable surface region, and the bending The surface region may include an electrode assembly having a uniform stacking section along the radial direction in which the number of stacked segments is uniform, and a decreasing stacking section located adjacent to the uniform stacking section, where the number of stacked segments decreases as it moves away from the uniform stacking section, and the stacking thickness of the segments in the uniform stacking section being 50 μm to 700 μm; a battery housing having an open end and a bottom opposite to it, housing the electrode assembly in the space between the open end and the bottom, and electrically connected to one of the positive electrode and the negative electrode to have a first polarity; a seal that seals the open end of the battery housing; and a terminal electrically connected to the other of the positive electrode and the negative electrode, with its surface exposed to the outside to have a second polarity.

[0170] Preferably, the battery according to the present invention may further include a current collector welded to the uniform layer number section such that the uniform layer number section and the welded area overlap. The layer thickness of the segment in the welded area may be 50 μm to 700 μm.

[0171] The above challenges are addressed by a battery pack containing multiple of the aforementioned batteries.

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

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

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

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

[0176] In other embodiments, the battery pack may include multiple busbars connecting multiple batteries in series and parallel.

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

[0178] The above challenges are addressed by a vehicle that includes the aforementioned battery pack. [Effects of the Invention]

[0179] According to one embodiment of the present invention, by using the plain portions protruding from the upper and lower parts of the electrode assembly as electrode tabs, the internal resistance of the battery can be reduced and the energy density increased.

[0180] According to another embodiment of the present invention, by improving the structure of the plain portion of the electrode assembly so that the electrode assembly and the inner circumferential surface of the battery housing do not interfere with each other during the beading portion formation process of the battery housing, it is possible to prevent internal short circuits in the cylindrical battery due to partial deformation of the electrode assembly.

[0181] According to yet another embodiment of the present invention, the structure of the plain portion of the electrode assembly can be improved to prevent the plain portion from tearing when bent, and the number of overlapping layers of the plain portion can be sufficiently increased to improve the welding strength of the current collector.

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

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

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

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

[0186] According to yet another embodiment of the present invention, it is possible to provide a cylindrical battery having a structure with low internal resistance, prevention of internal short circuits, and improved welding strength between the current collector and the blank portion, a battery pack including the same, and an automobile.

[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 an automobile.

[0188] The present invention also provides a variety of other effects, which will be described later with reference to examples. However, effects that can be easily inferred by an ordinary person will not be explained.

[0189] The following drawings accompanying this specification illustrate preferred embodiments of the invention and, together with the detailed description of the invention, serve to further illustrate the technical idea of ​​the invention; therefore, the invention should not be construed as being limited solely to what is shown in the drawings. [Brief explanation of the drawing]

[0190] [Figure 1] This is a plan view showing the structure of electrodes used in the manufacture of conventional tablet cylindrical batteries. [Figure 2] This diagram shows the electrode winding process for a conventional cylindrical tablet battery. [Figure 3] This diagram illustrates the process of welding a current collector to the bent surface area of ​​the plain section in a conventional tabletless cylindrical battery. [Figure 4] This is a plan view showing the structure of an electrode according to the first embodiment of the present invention. [Figure 5] This is a plan view showing the structure of an electrode according to a second embodiment of the present invention. [Figure 6] This is a plan view showing the structure of an electrode according to a third embodiment of the present invention. [Figure 7a] This is a plan view showing the structure of an electrode according to the fourth embodiment of the present invention. [Figure 7b] This figure shows the definitions of the width, height, and spacing pitch of the section according to an embodiment of the present invention. [Figure 7c] This figure shows the arc formed by the lower end of a segment, which defines the width of a segment, relative to the core center of the electrode assembly, when the electrode is wound according to an embodiment of the present invention. [Figure 7d] This figure schematically shows the relationship between the heights h1, h2, h3, h4 of the segment sections, the core radius rc, and the radii r1, r2, r3, r4 of the winding turns where the segment sections begin to appear, according to an embodiment of the present invention. [Figure 7e] This is a conceptual diagram for determining the maximum value hmax with respect to the subintercept height H in the subintercept height variable interval. [Figure 7f] This is a schematic diagram illustrating the formula for determining the lower interior angle θ of the segment. [Figure 7g] This is a plan view showing the deformed structure of an electrode according to a fourth embodiment of the present invention. [Figure 7h] This is a top view showing independent regions where multiple segments can be positioned when an electrode according to a modification of the present invention is wound up as an electrode assembly. [Figure 8a] This is a plan view showing the structure of an electrode according to the fifth embodiment of the present invention. [Figure 8b] This figure shows the definitions of the width, height, and spacing pitch of the section according to another embodiment of the present invention. [Figure 8c] This is a plan view showing the deformed structure of an electrode according to the fifth embodiment of the present invention. [Figure 9] This figure shows the segmented structure obtained by various modifications of the present invention. [Figure 10a] This is a schematic diagram showing a cross-section of a bent surface region formed as the section is folded toward the core side of the electrode assembly. [Figure 10b] This is a schematic perspective view of an electrode assembly with a bent surface region formed thereon. [Figure 10c] This graph shows the results of counting the number of stacked segments along the radial direction in the bent surface region 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. [Figure 10d] This graph shows the results of counting the number of stacked segments measured along the radial direction in the bent surface region of the positive electrode formed on the upper part of the electrode assemblies 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] This graph shows the results of counting the number of stacked segments measured along the radial direction in the bent surface region of the positive electrode formed on the upper part of the electrode assembly according to Examples 6-1 to 6-6 and Examples 7-1 to 7-6. [Figure 10f] This is a top view of an electrode assembly showing a uniform layer number section b1 and a decreasing layer number section b2 in the folded surface region of a section according to an embodiment of the present invention. [Figure 11] This is a cross-sectional view of a jelly roll-type electrode assembly, in which the electrodes of the first embodiment are applied to the first electrode (positive electrode) and the second electrode (negative electrode), cut along the Y-axis direction (winding axis direction). [Figure 12] This 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), cut along the Y-axis direction (winding axis direction). [Figure 13] This is a cross-sectional view of a jelly roll-type electrode assembly, cut along the Y-axis direction (winding axis direction), in which one of the electrodes from the 3rd to 5th embodiments (and their variations) is applied as the first electrode (positive electrode) and the second electrode (negative electrode). [Figure 14] This is a cross-sectional view of an electrode assembly according to yet another embodiment of the present invention, cut along the Y-axis direction (winding axis direction). [Figure 15] This is a cross-sectional view of an electrode assembly according to yet another embodiment of the present invention, cut along the Y-axis direction (winding axis direction). [Figure 16] This is a cross-sectional view of an electrode assembly according to yet another embodiment of the present invention, cut along the Y-axis direction (winding axis direction). [Figure 17] This is a cross-sectional view of a cylindrical battery according to one embodiment of the present invention, cut along the Y-axis. [Figure 18] This is a cross-sectional view of a cylindrical battery according to another embodiment of the present invention, cut along the Y-axis. [Figure 19] This is a cross-sectional view of a cylindrical battery according to yet another embodiment of the present invention, cut along the Y-axis. [Figure 20] This is a cross-sectional view of a cylindrical battery according to yet another embodiment of the present invention, cut along the Y-axis. [Figure 21] A cross-sectional view of a cylindrical battery according to another embodiment of the present invention, cut along the Y-axis direction. [Figure 22] A cross-sectional view of a cylindrical battery according to another embodiment of the present invention, cut along the Y-axis direction. [Figure 23] A cross-sectional view of a cylindrical battery according to another embodiment of the present invention, cut along the Y-axis direction. [Figure 24] A cross-sectional view of a cylindrical battery according to another embodiment of the present invention, cut along the Y-axis direction. [Figure 25] A cross-sectional view of a cylindrical battery according to another embodiment of the present invention, cut along the Y-axis direction. [Figure 26] A top view showing the structure of a first current collector according to an embodiment of the present invention. [Figure 27] A top view showing the structure of a second current collector according to an embodiment of the present invention. [Figure 28] A top view showing a state in which a plurality of cylindrical batteries are electrically connected. [Figure 29] A partially enlarged view of FIG. 28. [Figure 30] A diagram schematically showing the configuration of a battery pack according to an embodiment of the present invention. [Figure 31] A diagram schematically showing an automobile including a battery pack according to an embodiment of the present invention.

Embodiments for Carrying Out the Invention

[0191] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms and words used in this specification and the claims should not be construed as being limited to their ordinary and dictionary meanings. The inventor himself must interpret them in accordance with the meaning and concept corresponding to the technical idea of the present invention in accordance with the principle that he can appropriately define the concept of the terms in order to explain the invention in the best way.

[0192] Therefore, it should be understood that the embodiments described in this specification and the configurations shown in the drawings are only the most desirable embodiment of the present invention and do not represent all of the technical ideas of the present invention. Therefore, there may be various equivalents and modifications that can replace them at the time of this application.

[0193] Also, for the purpose of assisting in the understanding of the invention, the attached drawings are not illustrated at actual scale, and the dimensions of some components may be exaggerated. Also, the same reference numerals may be assigned to the same components in different embodiments.

[0194] The expression that two comparison targets are the same means "substantially the same". Therefore, "substantially the same" may include cases where there are deviations regarded as low levels in the industry, for example, deviations within 5%. Also, that a parameter is uniform in a given region means that it is uniform from an average perspective in the corresponding region.

[0195] [[ID=)1]] Also, although terms such as first, second, etc. are used to indicate various components, these terms are not for limiting the components. These terms are merely used 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 specified, each component can be singular or plural.

[0197] That any configuration is arranged "above (or below)" a component or "on (or under)" a component means not only that any configuration is arranged in contact with the upper surface (or lower surface) of the component, but also that other configurations may be interposed between the component and any configuration arranged above (or below) the component.

[0198] Furthermore, when one component is said to be “connected,” “joined,” or “linked” to another component, this includes not only cases where the components are directly connected to or linked to each other, but also cases where other components are “interposed” between each component, or where each component is “connected,” “joined,” or “linked” through other components.

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

[0200] In this specification, for the sake of explanation, 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 peripheral direction (X-axis direction). The direction that approaches or moves away from the winding shaft is referred to as the radial direction. Of these, the direction that approaches the winding shaft is referred to as the centripetal direction, and the direction that moves away from the winding shaft is referred to as the centrifugal direction.

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

[0202] Preferably, at least one of the first electrode and the second electrode includes a plain portion at the long edge in the winding direction that is not coated with the active material. At least a portion of the plain portion is used as an electrode tab. The plain portion includes a core-side plain portion adjacent to the core of the electrode assembly, an outer-circumferential plain portion adjacent to the outer surface of the electrode assembly, and an intermediate plain portion interposed between the core-side plain portion and the outer-circumferential plain portion.

[0203] Preferably, at least one of the plain core portion and the plain outer perimeter portion is relatively lower in height than the plain intermediate portion.

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

[0205] Referring to Figure 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 a conductive metal, such as aluminum or copper, and is appropriately selected according to the polarity of the electrode 40. The 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 a plain portion 43 at the long side end in the winding direction X. The plain portion 43 is a part of the current collector 41 that is not coated with the 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 short-side direction of the current collector 41 can be 50 mm to 120 mm, and the length of the active material portion in the long-side direction of the current collector 41 can be 3 m to 5 m. Therefore, the ratio of the short side to the long side of the active material portion can be 1.0% to 4.0%.

[0207] Preferably, in the electrode 40, the width of the active material portion in the short-side direction of the current collector 41 may be 60 mm to 70 mm, and the length of the active material portion in the long-side direction of the current collector 41 may be 3 m to 5 m. Therefore, the ratio of the short side to the long side 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%–11% level of the long-side-to-short-side ratio of the active material portion of electrodes used in cylindrical batteries with a 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 / mm². 2 ~35 kgf / mm 2This is possible. The elongation and tensile strength can be measured according to the IPC-TM-650 measurement method. The electrode 40 is manufactured by forming an active material layer 42 on the current collector 41 and then crimping it. During crimping, the elongation of the plain area 43 and the active material layer 42 area differs. Therefore, swell occurs in the electrode 40 after crimping, and the swell becomes more severe as the length of the electrode 40 increases.

[0210] Optimizing the elongation ratio and tensile strength of the current collector 41 reduces the camber length after crimping to less than 20 mm when the length of the electrode 40 is at a level of 4 m. The camber length is the maximum deflection of the electrode 40 in the winding direction X when the undulating electrode 40 is unfolded. The maximum deflection can be measured at the outer end. Because the electrode 40, for which the elongation ratio and tensile strength of the current collector 41 are optimized, has a short camber length, meandering defects do not occur during notching of the plain section 43 or during the winding process of the electrode 40.

[0211] The current collector 41 is more prone to breakage the smaller its elongation ratio. If the elongation ratio of the current collector 41 is less than 1.5%, the rolling processability of the current collector 41 decreases, and there is a risk of wire breakage in the current collector 41 when the electrode 40 coated with the active material layer 42 is crimped onto the current collector 41. 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 stretched, and the camber length increases significantly. The tensile strength of the current collector 41 is 25 kgf / mm². 2 Less than or 35 kgf / mm 2 If it exceeds this value, the electrode processability of electrode 40 decreases.

[0212] The camber phenomenon is particularly problematic in positive electrode current collectors made of aluminum foil. This invention achieves an elongation ratio of 1.5% to 3.0% and a tensile strength of 25 kgf / mm². 2 ~35 kgf / mm 2 By using 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 the positive electrode.

[0213] Preferably, an insulating coating layer 44 may be formed at the boundary between the active material layer 42 and the plain part 43. The insulating coating layer 44 is formed so that at least a part thereof overlaps with the boundary between the active material layer 42 and the plain part 43. The insulating coating layer 44 prevents a short circuit between two electrodes of opposite polarities facing each other with a separator interposed therebetween. The insulating coating layer 44 may cover the boundary portion between the active material layer 42 and the plain part 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 contains a polymer resin and may contain an inorganic filler such as Al2O3. The portion of the current collector 41 covered by the insulating coating layer 44 may be regarded as a plain part because it is not an area coated with the active material layer.

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

[0215] The core-side plain part B1, the outer-periphery-side plain part B3, and the intermediate plain part B2 may be defined as the plain part of the region adjacent to the core side, the plain part of the region adjacent to the outer periphery side, and the plain part of the other regions excluding these when the electrode 40 is wound as a jelly-roll type electrode assembly, respectively.

[0216] Hereinafter, the core-side plain part B1, the outer-periphery-side plain part B3, and the intermediate plain part B2 are referred to as the first part, the second part, and the third part, respectively.

[0217] As an example, the first part B1 may be the plain part of the electrode region including the innermost winding turn, and the second part may be the plain part of the electrode region including the outermost winding turn. The winding turns may be counted based on the core-side end of the electrode assembly.

[0218] As another example, the B1 / B2 boundary can be appropriately defined at the point where the height (or variation pattern) of the plain area substantially changes from the core side to the outer circumference of the electrode assembly, or at a predetermined percentage point relative to the radius of the electrode assembly (e.g., 5%, 10%, 15% of the radius).

[0219] The B2 / B3 boundary can be defined at the point where the height (or variation pattern) of the plain area substantially changes from the outer periphery of the electrode assembly toward the core, or at a predetermined percentage point relative to the radius of the electrode assembly (e.g., 85%, 90%, 95% of the radius). Once the B1 / B2 boundary and the B2 / B3 boundary are identified, the third portion B2 can 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 circumference of the electrode assembly. For example, the second portion can be defined as the plain area of ​​the electrode region constituting 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 plain area of ​​the electrode region constituting the innermost winding turn.

[0221] This does not rule out the possibility of other structures intervening between the first part B1 and the third part B2. Nor does it rule out the possibility of other structures intervening between the third part B2 and the second part B3.

[0222] In the first embodiment, the height of the plain section 43 is not constant and varies relatively in the winding direction X. That is, the height (length in the Y-axis direction) of the second section B3 is 0 or greater and is relatively lower than that of the first section B1 and the third section B2. Here, the height of each section may be the average height or the maximum height, and so on. In the winding direction, the length of the third section B2 is even longer than that of the first section B1 and the second section B3.

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

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

[0225] In one modified example, the second part B3 can be transformed into a stepped shape in which the height decreases in stages (see dotted line).

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

[0227] Referring to Figure 6, in the third embodiment, the electrode 50 has a height of 0 or greater for the first portion B1 and the second portion B3, and is relatively lower than the third portion B2. Also, 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 stepped shape that increases gradually from the core side to the outer circumference side.

[0229] Patterns 1 to 7 divide the third section B2 around the position where the height of the plain section 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 plain section 43. Stress distribution is to prevent the plain section 43 from tearing when it is bent towards the core side of the electrode assembly.

[0230] Width d of Part B1 B1 The design applies the condition that when the pattern of the third part B2 is folded towards the core, it does not block the core of the electrode assembly. The core refers to the cavity located at the winding center of the electrode assembly.

[0231] For example, the width dB1 of the first section B1 may increase in proportion to the fold length of pattern 1. The fold length corresponds to the height of the pattern relative to the fold point of the pattern.

[0232] Preferably, the width d of the first part B1. B1 The radial width of the winding turn formed by the first part B1 can be set to be greater than or equal to the bending length of pattern 1. In the modified example, the width d of the first part B1 B1 This can be set such that the value obtained by subtracting the radial width of the winding turn formed by the first part B1 from the bending length of pattern 1 is less than 0 or less than or equal to 10% of the core radius.

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

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

[0235] In one modified example, the height of the third portion B2 may have a stepped shape that increases from the core side to the outer circumference side and then decreases.

[0236] In other modifications, the second part B3 may be modified to have the same structure as in the second embodiment.

[0237] In further variations, the pattern structure applied to the third part B2 can be extended to the second part B3 (see dotted line).

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

[0239] Referring to Figure 7a, in the fourth embodiment, the electrode 60 has a height of 0 or greater in the winding axis (Y) direction for the first portion B1 and the second portion B3, and is relatively lower than the third portion B2. Also, the height of the first portion B1 and the height of the second portion B3 in the winding axis (Y) direction may be the same or different.

[0240] Preferably, the third part B2 may include a plurality of subsections 61 in at least a portion of its length. The subsections 61 may have a height that increases gradually from the core side to the outer periphery side. The subsections 61 have a geometric shape in which the width decreases from the bottom to the top. Preferably, the geometric shape is trapezoidal. As will be described later, the geometric shape can be deformed in various ways.

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

[0242] In the fourth embodiment, in order to prevent damage to the active material layer 42 and / or insulating coating layer 44 when bending the plain portion 43, it is desirable to provide a predetermined gap between the lower end of the cutting groove between the segment pieces 61 (G in Figure 7b) and the active material layer 42. This is because stress is concentrated near the lower end of the cutting groove 63 when the plain 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. By adjusting the gap to the above numerical range, it is possible to prevent damage to the active material layer 42 and / or insulating coating layer 44 near the lower end of the cutting groove 63 due to stress generated when bending the plain portion 43. In addition, the gap can prevent damage to the active material layer 42 and / or insulating coating layer 44 due to tolerances during notching or cutting of the segment pieces 61. In one direction parallel to the winding direction, the gap may be substantially the same or vary. In the latter case, the gaps between multiple segments can vary individually, in groups, or in groups of two or more along one direction parallel to the winding direction. The lower end of the cutting groove 63 and the insulating coating layer 44 can be separated by 0.5 mm to 2.0 mm. In one direction parallel to the winding direction, the separation distance between the lower end of the cutting groove 63 and the insulating coating layer 44 may be substantially the same or vary. In the latter case, the separation distances between multiple segments can vary individually, in groups, or in groups of two or more along one 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 in the range of -2 mm to 2 mm along the winding axis direction with respect to the end of the separation film. The insulating coating layer 44 can prevent short circuits between two electrodes of opposite polarity facing each other across the separation film and can support the bending point when the segment 61 is bent. To improve the short-circuit prevention effect between the two electrodes, the insulating coating layer 44 may be exposed to the outside of the separation film. Furthermore, to further maximize the short-circuit prevention effect 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 located 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 relative to 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 separation film.

[0243] In one embodiment, the multiple sections 61 may form multiple sections in groups, extending from the core side to the outer periphery. At least one of the width, height, and spacing pitch of sections belonging to the same section group may be substantially the same. Preferably, the width, height, and spacing pitch of sections belonging to the same section group may be the same as each other.

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

[0245] In other forms, the sections may be arranged in groups or in groups of two or more groups, with the spacing pitch gradually or steppedly increasing from the core side to the outer periphery side, or vice versa.

[0246] In yet another form, the multiple sections may, in groups or in groups of two or more, have a separation pitch that gradually or stepwise increases from the core side to the outer periphery side, then gradually or stepwise decreases, or vice versa.

[0247] In yet another embodiment, the multiple sections may have a gap between the lower end of the cutting groove 63 and the insulating coating layer 44 or active material layer 42 that increases gradually or stepwise from the core side to the outer circumference, or vice versa.

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

[0249] Figure 7b shows the definitions of the width D, height H, and separation pitch P of the trapezoidal segment 61.

[0250] Referring to Figure 7b, the width D, height H, and separation pitch P of the segment 61 are designed to prevent the plain section 43 from tearing near the bending point during bending and to ensure sufficient welding strength, while also preventing abnormal deformation of the plain section 43 by sufficiently increasing the number of overlapping layers of the plain section 43.

[0251] The folding of the segment 61 is performed along or above the line G passing through the lower end of the cutting groove 63. The cutting groove 63 allows for smooth and easy folding of the segment 61 in the radial direction of the electrode assembly.

[0252] The width D of the segment 61 is defined by the distance between two points where two straight lines extending from the 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 by the shortest distance between the uppermost edge of the segment 61 and the straight line extending from the bottom 63a of the cutting groove 63. The spacing pitch P of the segment 61 is defined by the distance between two points where a straight line extending from the bottom 63a of the cutting groove 63 intersects with straight lines extending from the two side edges 63b connected to the bottom 63a. When the side edges 63b and / or the bottom 63a are curves, the straight lines can be replaced by tangents extending from the side edges 63b and / or the bottom 63a at the intersection of the side edges 63b and the bottom 63a.

[0253] Preferably, the width D of the segment 61 is 1 mm or more. If D is less than 1 mm, when the segment 61 is bent toward the core, the segment 61 may not overlap to a sufficient extent to ensure sufficient welding strength, or a gap may be created.

[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, such that the segment 61 easily overlaps radially when the segment 61 is bent toward the core side of the electrode assembly.

[0255] Figure 7c shows the lower end of the segment 61 (line segment D in Figure 7b) where the width D of the segment 61 is defined when the electrode 60 is wound according to an embodiment of the present invention. ab This diagram shows the arcs A1A2 formed by the electrode assembly relative to the core center O.

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

[0257] When the lengths of the arcs A1 and A2 of the segment 61 are the same, the inscribed angle Φ decreases as the radius r of the winding turn in which the segment 61 is located increases. Conversely, when the inscribed angle Φ of the segment 61 is the same, the lengths of the arcs A1 and A2 increase proportionally as the radius r of the winding turn in which the segment 61 is located increases.

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

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

[0260] In one embodiment, the inscribed angle Φ of the segmentation section 61 may gradually or stepwise increase or decrease along the radial direction of the electrode assembly within the above numerical range. In another embodiment, the inscribed angle Φ of the segmentation section 61 may gradually or stepwise increase and then gradually or stepwise decrease along the radial direction of the electrode assembly within the above numerical range, and vice versa is also possible. In yet another embodiment, the inscribed angle Φ of the segmentation section 61 may be substantially the same along the radial direction of the electrode assembly within the above numerical range.

[0261] Experiments have shown that when the inscribed angle Φ of the segment 61 exceeds 45°, the folding pattern of the segment 61 becomes uneven. The difference in force applied to the central and side portions of the segment 61 becomes large, resulting in uneven pressure on the segment 61 in the circumferential direction. Furthermore, if the pressing force is increased to ensure folding uniformity, cracks may occur in the plain area 43 near the cutting groove 63.

[0262] In one example, the inscribed angles Φ of the segmental sections 61 contained within the electrode 60 are substantially identical, and the width of the segmental section 61 may increase proportionally as the radius r of the winding turn in which the segmental section 61 is located increases. Substantially identical means either completely identical or with a deviation of less than 5%.

[0263] For example, if the radius of the electrode assembly is 22 mm, the radius of the core is 4 mm, and the segment 61 is positioned from a winding turn located at a radius of 7 mm, and the inscribed angle Φ of the segment 61 is constant at 28.6°, then the width D of the segment 61 can increase proportionally with respect to the radius r of the winding turn in which the segment 61 is located, as shown in Table 1 below. That is, the width of the segment 61 can 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 at a winding turn with radius r relative to the core center O of the electrode assembly can be determined within the range that satisfies the following equation 1. [Formula 1] 1≦D(r)≦(2×π×r / 360°)×45°

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

[0266] In other embodiments, each of the multiple subsections 61 may have a winding width D(r) that increases gradually or in steps in the winding direction, ranging from 1 mm to 11 mm, as the radius r of the winding turn in which the subsection 61 is located increases with respect to the core center of the electrode assembly, or vice versa.

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

[0268] In yet another embodiment, each of the multiple subsections 61 may have a winding width D(r) 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 subsection 61 is located increases with respect to the core center of the electrode assembly, or vice versa.

[0269] In other configurations, 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 may be the same or different.

[0270] In other configurations, as the radius r of the winding turn in which the segment 61 is located increases, the rate at which the width D(r) of the segment 61 changes in the range of 1 mm to 11 mm may be the same or different.

[0271] Referring further to Figure 7b, the height H of the segment 61 may be 2 mm or more. If D2 is less than 2 mm, when the segment 61 is bent toward the core, the segment 61 may not overlap to a sufficient extent to ensure sufficient welding strength, or a gap may be created.

[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 it is folded toward the core. Preferably, the height H of the segment 61 can be adjusted so that 90% or more of the core's diameter is open to the outside.

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

[0274] In one example, the height H of the segment 61 increases from h1 to h as the radius of the winding turn increases. N If we assume that it increases stepwise over N steps, then the k-th height of the segment 61 is h k (k is a natural number from 1 to N), height h k The starting radius of the winding turn is r, which includes a segment 61 having a segment 61. k , the radius of the core is r c Therefore, the heights h1 to h of the segment 61 must satisfy equation 2 below. N This may be decided. [Formula 2] 2mm≦h k ≤r k -α×r c (Ideally, α should be 0.90-1)

[0275] Height h of segment 61 k If equation 2 is satisfied, then even if the segment 61 is bent toward the core, more than 90% of the core's diameter can be exposed to the outside.

[0276] For example, if the overall winding turn radius of electrode 60 is 22 mm, the height of the segment 61 starts at 3 mm, and for every 1 mm increase in the radius of the winding turn containing the segment 61, the height of the segment 61 increases sequentially to 3 mm, 4 mm, 5 mm, and 6 mm, and the height can be maintained substantially the same at 6 mm in the remaining winding turns. That is, of the radius of the overall winding turn, the radial width of the height-variable section of the segment 61 is 3 mm, and the remaining radial section corresponds to the height-uniform section.

[0277] In this case, the starting radii r1, r2, r3, and r4 of the winding turns, which include segment sections 61 having heights of 3 mm, 4 mm, 5 mm, and 6 mm depending on the radius rc of the electrode assembly core, 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 core is not blocked by the segment 61 even if it is bent towards the core. On the other hand, r1, r2, r3, and r4 shown in Table 2 can be shifted towards the core depending on the α value. In one example, when α is 0.90, r1, r2, r3, and r4 can be shifted towards the core by 10% of the core radius. In this case, when the segment 61 is bent towards 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 starting position of the segment 61. Therefore, the position of the segment 61 can be shifted by a predetermined distance towards the outer circumference from the radius shown in Table 2. Figure 7d shows the heights h1, h2, h3, and h4 of the segment 61, and the core radius r c This figure schematically shows the relationship between the radii r1, r2, r3, and r4 of the winding turn where the segment 61 begins to appear.

[0279] Referring to Table 2 and Figure 7d, for example, the radius r of core C cWhen the radius is 3m, the starting radii r1, r2, r3, and r4 of the winding turns containing segment sections 61 with heights of 3mm(h1), 4mm(h2), 5mm(h3), and 6mm(h4) can be 6mm, 7mm, 8mm, and 9mm, respectively, and the height of the segment section 61 can be maintained at 6mm from radius 9mm to the last winding turn. Also, winding turns with radii smaller than 6mm(r1) do not need to contain segment sections 61. In such an example, since the segment section 61 with a height of 3mm(h1) closest to the core C is located from a winding turn with a radius of 6mm, even if the segment section 61 is bent toward the core C, it will only cover the radius section from 3mm to 6mm and will not substantially block the core C. Depending on the α value in Equation 2, the position of the segment section 61 is determined by the core radius r c It can be shifted to the core C side by up to 10%.

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

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

[0282] Figure 7e shows the maximum value h with respect to the height H of the subsection 61 in the height-variable interval of the subsection 61. max This is a conceptual diagram for determining the outcome.

[0283] Referring to Figure 7e, in the wound structure of the electrode assembly, electrode E1, which includes the segment 61, faces electrode E2 of opposite polarity in the radial direction, with the separation membrane S in between. Active material layers E are present on both sides of electrode E1. 1,active The active material layer E is coated on both sides of electrode E2. 2,active It is coated. For electrical insulation, the edges S of the separator film S end This is the end of electrode E2. 2,end From the insulation gap W gapIt can be further extended outward by a length corresponding to the length. Also, the end of electrode E1 is not extended outward beyond the end of electrode E2 for electrical insulation. Therefore, there is an insulating gap W at the lower end of the plain section 43. gap A corresponding section must be secured. Also, when electrodes E1 and E2 and the separation membrane S are wound up, the end S of the separation membrane S end This causes meandering. Therefore, for the section 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 exposed. margin,min The blank section 43 must be allocated to it. Also, in order to cut the segment 61, a minimum cutting scrap margin W must be placed at the end of the current collector foil. scrap,min A value must be assigned. Therefore, the maximum height h of the subsection 61 in the height-variable section of the subsection 61. max This can be determined by the following equation 3. In equation 3, W foil This 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 insulation gap W gap The insulation gap W can be 0.2 mm to 6 mm when the first electrode is the positive electrode. gap This can be 0.1 mm to 2 mm when the first electrode is the negative electrode.

[0285] Preferably, the minimum cutting scrap margin W scrap,min This can be 1.5mm to 8mm. Minimum cutting scrap margin W scrap,min This does not have to be assigned by the process of forming the segment 61. For example, the cutting groove 63 can be formed so that the upper edge of the segment 61 coincides with the upper edge of the current collector wheel. In this case, in equation 3, W scrap,min It can be 0.

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

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

[0288] Referring to Table 3, the maximum height h of the subsection 61 in the height-variable section of the subsection 61 max The height can 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 can be increased stepwise or gradually along the radial direction of the electrode assembly in the 2 mm to 10 mm range. Referring further to Figure 7b, the separation pitch P of the segment 61 can be adjusted in the range of 0.05 to 1 mm. If the separation pitch P is less than 0.05 mm, when the electrode 60 runs during the winding process, etc., stress may cause cracks in the plain section 43 near the lower end of the cutting groove 63. On the other hand, if the separation pitch P exceeds 1 mm, when the segment 61 is bent, the segment 61 may not overlap to a degree that allows sufficient welding strength to be ensured, or gaps may be created.

[0289] On the other hand, if 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 runs at a speed of 100 mm / sec or more under a tension of 300 gf or more during the winding process, it is possible to prevent cracks from occurring at the bottom of the cutting groove 63.

[0290] According to experimental results, when the current collector 41 of the electrode 60 is 15 μm thick aluminum foil and the separation pitch P is 0.5 mm or more, no cracks occur at the bottom of the cutting groove 63 when the electrode 60 is running under the above-mentioned running conditions.

[0291] As shown in Figure 7b, a cutting groove 63 is interposed between two adjacent segment sections 61 in the winding direction X. The cutting groove 63 corresponds to the space created when the plain section 43 is removed. Preferably, the corners at both lower ends of the cutting groove 63 have a rounded shape. That is, the cutting groove 63 includes a substantially flat bottom 63a and a rounded portion 63c. The rounded portion 63c connects the bottom 63a to the side edge 63b of the segment section 61. In a modified example, the bottom 63a of the cutting groove 63 may be replaced with an arc shape. In this case, the side edge 63b of the segment section 61 can be smoothly connected by the arc shape of the bottom 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 between 0.01 mm and 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 at the bottom of the cutting groove 63 while the electrode 60 is running during the winding process or the like.

[0293] Multiple subsections 61 may have an increasing lower interior angle θ from the core side to the outer periphery. For example, the lower interior angle θ of multiple subsections 61 may increase gradually or in steps from the core side to the outer periphery. The lower interior angle θ is the angle between a straight line extending from the bottom 63a of the cutting groove 63 and a straight line extending from the side 63b of the subsection 61. When the subsection 61 is symmetrical, the lower interior angles θ on the left and right sides are substantially the same.

[0294] As the radius of the electrode assembly increases, the radius of curvature increases. If the lower interior angle θ of the segment 61 increases with the increase in the radius of the electrode assembly, the stress generated in the radial and circumferential directions when the segment 61 is bent can be relieved. 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 region.

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

[0296] Figure 7f is a schematic diagram illustrating the formula for determining the lower interior angle θ of the segment 61.

[0297] Referring to Figure 7f, ideally, the sides of the segment 61 coincide with the line segments AE and DE that connect A and D, which are the ends 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 refer Assuming that line segment EF is approximately equal to line segments AE and DE, the width D of the segment 61 and the radius r of the winding turn in which the segment 61 is located can be approximately determined using the following equation 4. [Equation 4]

number

[0299] The angle in equation 4 is the lower interior angle θ of the segment 61. referis the ideal reference angle. On the other hand, there is a separation pitch P between adjacent partial segments 61 located in the same winding turn. The length of the separation pitch P is denoted as p. Since the separation pitch P exists between adjacent partial segments 61, a tolerance of 50% of the separation pitch P can be given to the lower inner angle θ. That is, the width of the upper end side BC of the partial segment 61 can increase by a maximum of p / 2 up to the upper end side B'C'. The lower inner angle θ' reflecting the tolerance can be expressed by the following formula 5. Lower inner angle θ refer is the ideal reference angle ∠BAG, and the lower inner angle θ' is the angle ∠B'AG' reflecting the tolerance due to the separation pitch P. In formula 5, H is the height of the partial segment 61, and p corresponds to the separation pitch. [Formula 5]

Number

[0300] Preferably, the lower inner angle θ of the partial segment 61 located in each winding turn of the electrode assembly can satisfy the following formula 6. Thereby, when the partial segment 61 is bent toward the core center of the electrode assembly, the adjacent partial segments 61 in the circumferential direction do not interfere with each other, and smooth bending is possible. [Formula 6]

Number

[0301] As an example, when the electrode 60 forms a winding structure with a diameter of 22 mm and a core radius of 4 mm, the lower inner angle of the partial segment 61 can gradually or stepwise increase in the range of 60° to 85° in the height variable section. [[ID=……]]

[0302] [[ID=……]] As another example, the plurality of partial segments 61 can gradually or stepwise increase the lower inner angle θ from the core side toward the outer peripheral side in one or two or more group units.

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

[0304] Referring further to Figure 7a, the width d of the first part B1 is B1 The design is such that when the segment 61 of the third part B2 is bent toward the core, the core of the electrode assembly is exposed to the outside by more than 90% of its diameter. B1 The width d of the first part B1 may increase in proportion to the bend length of the segment 61 of group 1. The bend length corresponds to the length from the bend point to the upper edge of the segment 61. Preferably, when the electrode 60 is used to manufacture an electrode assembly of a cylindrical battery of form factor 4680, the width d B1 This can be set from 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 bending point of the segment 61 can be set on a line passing through the lower end of the cutting groove 63 or at a predetermined distance above that line. If the segment 61 is bent toward the core at a predetermined distance from the lower end of the cutting groove 63, the radial superposition of the segment 61 becomes easier. When the segment 61 is bent, the outer segment presses against the inner segment with respect to the center of the core. At this time, if the bending point is a predetermined distance from the lower end of the cutting groove 63, the superposition of the segment 61 becomes easier as the inner segment is pressed against the outer segment in the winding axis direction by the outer segment. The separation distance of the bending point is preferably 1 mm or less. Since the minimum height of the segment 61 is 2 mm, the ratio of the separation distance of the bending point to the minimum height may be 50% or less.

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

[0307] In other modifications, the width of each segment group may be designed to constitute at least one winding turn of the electrode assembly.

[0308] In further variations, the width and / or height and / or spacing of the sections 61 belonging to the same section group may increase or decrease gradually and / or stepwise and / or irregularly within the group or between adjacent groups.

[0309] Groups 1 to 8 are merely examples of segment groups included in the third part B2. The number of groups, the number of segment segments 61 included in each group, and the width of the groups can be preferably adjusted so that the segment segments 61 overlap in multiple layers, thereby maximally distributing stress during the bending process of the plain section 43 and ensuring sufficient welding strength with the current collector.

[0310] In other variations, the height of the second portion B3 may decrease gradually or in stages, as in the first and second embodiments.

[0311] In further variations, the segmentation structure of the third part B2 can be extended to the second part B3 (see dotted line). In this case, the second part B3, like the third part B2, may contain multiple segments. Preferably, the segmentation structure of the second part B3 may be substantially identical to the outermost group of segments in the third part B2. In this case, the segments contained in the second part B3 and the third part B2 may have substantially the same width, height, and spacing pitch. As a variation, the segments of the second part B3 may have a larger width and / or height and / or spacing pitch than those of the third part B2.

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

[0313] In other words, in the third part B2, the height of the segment 61 is h1~h N When it increases gradually up to h1~h N-1(N is a height index, a natural number of 2 or more) The section where the segmented slice 61 having a height is arranged corresponds to a height variable section, h N The section where the segmented slice 61 having a height of h N corresponds to a height uniform section. The ratio of the height variable section to the height uniform section with respect to the length of the electrode 60 in the winding direction will be described later by referring to specific examples.

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

[0315] The reason why the widths of groups 1 to 8 do not show a constant increase or decrease pattern is that the width of the segmented slice gradually increases from group 1 to group 8, but the number of segmented slices included in each group is limited to an integer, and the thickness of the electrode has a slight deviation in the winding direction. Therefore, the number of segmented slices can decrease in a specific segmented slice group. Therefore, the width of the group can show an irregular change pattern as exemplified above from the core side to the outer peripheral side.

[0316] That is, in the circumferential direction of the electrode assembly, when the widths in the winding direction for each of three continuously adjacent segmented slice groups are W1, W2, and W3, respectively, it may include a combination of segmented slice groups where W3 / W2 is smaller than W2 / W1.

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

[0318] In further variations, when the plain portion 43 of the electrode 60 has a segmented structure, the electrode 60 may include segmented section omission sections 64 in which some of the segments are regularly or irregularly omitted, as shown in Figure 7g.

[0319] Preferably, there may be multiple subsection omission sections 64. For example, the width of a subsection omission section 64 may be constant from the core side to the outer periphery side. As another example, the width of a subsection omission section 64 may increase or decrease regularly or irregularly from the core side to the outer periphery side. Preferably, the height of the blank area in a subsection omission section 64 may correspond to the height of the first section B1 and / or the second section B3.

[0320] The number of segmental segments 61 present in the segmental segment omission section 64 can be at least one. The electrode 60 may include blank sections, as shown in Figure 7g, where the number of segmental segments 61 present in the segmental segment omission section 64 increases from the core side to the outer circumference side.

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

[0322] In other words, when the electrode assembly 65 is viewed in the direction of the winding axis, the multiple segments 61 can be located within multiple independent regions 66 with respect to the core center C. The number of independent regions 66 can vary to two, three, four, five, or the like.

[0323] Preferably, the independent regions 66 may be sector-shaped. In this case, the angles between the independent regions 66 may be substantially the same. Also, the inscribed angle δ of the independent regions 66 may be 20° or more, selectively 25° or more, selectively 30° or more, selectively 35° or more, or selectively 40° or more.

[0324] In the modified example, the independent region 66 may have the form of a geometric figure such as a square, rectangle, parallelogram, or trapezoid.

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

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

[0327] Referring to Figure 8a, the electrode 70 of the fifth embodiment is substantially identical in its configuration to that of the above-described embodiment, except that the shape of the segment 61' differs. Therefore, unless otherwise specified, the configuration of the fourth embodiment can be similarly applied to the fifth embodiment.

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

[0329] Figure 8b shows the definitions of the width, height, and spacing pitch of the rectangular section 61'.

[0330] Referring to Figure 8b, the width D, height H, and separation pitch P of the segment 61' are set to sufficiently increase the number of overlapping layers of the plain section 43 and to prevent abnormal deformation of the plain section 43 in order to prevent the plain section 43 from tearing during bending and to improve the welding strength with the current collector. Abnormal deformation refers to the plain section below the bending point collapsing and deforming irregularly without being able to maintain a straight line.

[0331] The width D of the segment 61' is defined by the distance between two points where two straight lines extending from the side edges 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 by the shortest distance between the uppermost edge of the segment 61' and the straight line extending from the bottom 63a of the cutting groove 63. The spacing pitch P of the segment 61' is defined by the distance between two points where a straight line extending from the bottom 63a of the cutting groove 63 intersects with straight lines extending from two side edges 63b connected to the bottom 63a. When the side edges 63b and / or the bottom 63a are curves, the straight lines can be replaced by tangents extending from the side edges 63b and / or the bottom 63a at the intersection of the side edges 63b and the bottom 63a.

[0332] Preferably, the conditions relating to the width D, height H, and separation pitch P of the segment 61' are substantially the same as those of the fourth embodiment described above, so repeated explanations are omitted. However, since the segment 61' is rectangular, the lower interior angle of the segment 61' may be constant at 90°.

[0333] Similar to the electrode 60 of the fourth embodiment, the electrode 70 of the fifth embodiment may also include segment omission sections 64 in which some of the segments are omitted regularly or irregularly, as shown in Figure 8c.

[0334] Furthermore, when the electrode 70, which includes the segment omission section 64, is wound up as an electrode assembly, the segment may be located within a plurality of independent regions 66, as shown in Figure 7h.

[0335] As in the fourth and fifth embodiments, when the third portion B2 and the second portion B3 include multiple subsections 61, 61', the shape of each subsection 61, 61' can be varied in many ways.

[0336] Preferably, the sections can be deformed into a variety of shapes while satisfying at least one of the following conditions.

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

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

[0339] Condition 3: The width is maintained at a constant level from bottom to top.

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

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

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

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

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

[0345] Condition 9: The interior angle on one side of the lower section is the same as the interior angle on the other side.

[0346] Here, the interior angle can 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 a curve, the interior angle is defined as the angle between the tangent line drawn at the lowest point of the curve and the width direction of the lower part of the segment.

[0347] Condition 10: The interior angle on one side of the lower section is different from the interior angle on the other side.

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

[0349] Condition 12: It is symmetrical with respect to the winding axis direction.

[0350] Condition 13: It is asymmetrical with respect to the winding axis direction.

[0351] Condition 14: The sides are straight.

[0352] Condition 15: The sides are curved.

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

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

[0355] Condition 18: The upper and / or lower corners are structured as straight lines intersecting each other.

[0356] Condition 19: The upper and / or lower corners have a structure where a straight line and a curve intersect.

[0357] Condition 20: The upper and / or lower corners are structured in a way that curves intersect.

[0358] Condition 21: The upper and / or lower corners are rounded.

[0359] Figure 9 is an illustrative diagram showing the shape of a section obtained by a modification of the present invention.

[0360] As illustrated, the section can have a variety of geometric shapes with a dotted line connecting the bottoms of the cutting grooves on both sides as its base. The geometric shape has a structure in which at least one straight line, at least one curve, or a combination thereof is connected. As an example, the section can have a variety of shapes, such as polygons, round shapes, or combinations thereof.

[0361] Specifically, the segment may be a symmetrical trapezoid (a), an asymmetrical trapezoid (b), a parallelogram (c), a triangular (l), a pentagon (k), an arc (e), or an ellipse (f).

[0362] The shape of the section is not limited to that shown in Figure 9, and can be modified to other polygonal shapes, other round shapes, or combinations thereof, so as to satisfy at least one of the conditions 1 to 21 described above.

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

[0364] In the polygonal shapes (a), (b), (c), (k), and (l) of the segmental sections and the rounded shapes (e) and (f) of the segmental sections, the interior angles θ1 and θ2 on one side of the lower section may be the same or different, and the interior angles θ1 and θ2 on the other side of the lower section may be acute, right, or obtuse, respectively. An interior angle is the angle between the base and the sides of a geometric figure. When the sides are curves, straight lines may be replaced by tangents extending from the intersection of the base and the sides.

[0365] The shape of the sides of polygonal segments can be varied in many ways.

[0366] For example, the side of the segmental section morphology (a) can be transformed into a curve that bulges outward, as in morphology (d), or into a curve that is concave inward, as in morphology (g) or morphology (j).

[0367] As another example, the sides of segmental segment morphology (a) can be transformed into a broken line that is concave inward, as in morphology (h) or morphology (i). Although not shown, the sides of segmental segment morphology (a) can also be transformed into a broken line that bulges outward.

[0368] In the morphologies of the segment sections (d), (g), (j), (h), and (i) with variously deformed sides, the interior angles θ1 and θ2 on one side of the lower section may be the same or different, and the interior angles θ1 and θ2 on the other side of the lower section may be acute, right, or obtuse, respectively.

[0369] The width of the segment can exhibit diverse patterns of change from the bottom to the top.

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

[0371] On the other hand, among the segmental section shapes illustrated in Figure 9, the polygonal shape with a flattened top can be rotated by 180°. For example, when segmental section shapes (a), (b), (d), or (g) are rotated by 180°, the width of the segmental section may gradually increase from the bottom to the top. As another example, when segmental section shape (h) is rotated by 180°, the width of the segmental section may remain constant from the bottom to the top and then gradually increase.

[0372] In the above-described embodiment (modification), according to another embodiment of the present invention, it is also possible to change the shape of the subsections 61, 61' along the region of the third part B2. For example, a round shape (e.g., semicircular, elliptical, etc.) that is advantageous for stress distribution can be applied to sections where stress is concentrated, and a polygonal shape (e.g., square, trapezoidal, parallelogram, etc.) that maximizes the area can be applied to sections where the stress is relatively low.

[0373] In other embodiments, the multiple sections may have different shapes individually, in groups, or in groups of two or more, along one direction parallel to the winding direction of the electrode assembly.

[0374] In the above-described embodiment (modified version), the segmentation structure of the third part B2 may also be applied to the first part B1. However, if the segmentation structure is applied to the first part B1, there is a risk that a reverse forming phenomenon will occur, where the ends of the first part B1 bend outward when the segmented pieces 61, 61' of the third part B2 are bent due to the radius of curvature of the core. Therefore, it is desirable not to apply the segmentation structure to the first part B1, or, if the segmentation structure is applied, to adjust the width and / or height and / or spacing pitch of the segmented pieces 61, 61' to a level where reverse forming does not occur, taking into account the radius of curvature of the core.

[0375] According to yet another embodiment of the present invention, after the electrodes 60 and 70 are wound up as an electrode assembly, the segments exposed on the upper and lower parts of the electrode assembly can overlap in multiple layers along the radial direction of the electrode assembly to form a bent surface region.

[0376] Figure 10a is a schematic diagram showing a cross-section of the bent surface region F formed when the segment 61 is bent toward the core C side of the electrode assembly 80. In Figure 10a, the cross-section of the bent surface region F is shown only on the left side with respect to the winding axis of the electrode assembly 80. The bent surface region F can be formed on both the upper and lower parts of the electrode assembly 80. Figure 10b is a schematic perspective view showing the electrode assembly 80 on which the bent surface region F is formed.

[0377] Referring to Figures 10a and 10b, the bent surface region F has a structure in which the segmental segments 61 are superimposed in multiple layers in the winding axis direction. The superposition direction is the winding axis direction (Y axis direction). Section (1) is a segmental segment omitted section (first part B1) in which no segmental segments exist, and sections (2) and (3) are sections in which winding turns containing segmental segments 61 are located. Section (2) is a height variable section in which the height of the segmental segments 61 changes, and section (3) is a height uniform section in which the height of the segmental segments is maintained uniformly up to the outer circumference of the electrode assembly. As will be described later, the radial lengths of sections (2) and (3) may change. On the other hand, a plain section (second part B3) included in at least one winding turn, including the outermost winding turn, does not have to contain a segmental segment structure. In this case, the second part B3 can be excluded from section (3).

[0378] In section (2), the height of the segment 61 is equal to the radius r1~r of the electrode assembly 80. N Minimum height h1 (=h) in the interval min ) from maximum height h N ( = h max ) can change in stages up to r. The height-variable interval in which the height of the segment 61 changes is r1 to r N The radius is r. N From the radius R of the electrode assembly 80, the height of the segment 61 is h N It is maintained uniformly. Uniform height means that the height deviation is within 5%.

[0379] At any radial position in section (2) and section (3), the number of layers of the segment 61 varies depending on the radial position. The number of layers of the segment 61 is determined by the width of section (2) and the minimum height h1 and maximum height h in the variable height section of the segment 61. N Furthermore, it can vary depending on the change in height Δh of the segment 61. The number of stacked segment 61 is the number of segment segments that intersect a virtual line drawn in the winding axis direction from an arbitrary radial position of the electrode assembly 80.

[0380] Preferably, the height, width, and spacing pitch of the segmentation segments 61 can be adjusted according to the radius of the winding turn containing the segmentation segments 61, thereby optimizing the number of segments of the segmentation segments 61 at each position in the bent surface region F to match the required welding strength of the current collector.

[0381] First, when the minimum height h1 of the segment 61 is the same in the height-variable interval (interval (2)), the maximum height h of the segment 61 N The following will explain, with specific examples, how the number of layers of the segment 61 changes along the radial direction of the folded surface region F due to the change in [the specified parameter].

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

[0383] In each embodiment, the minimum height of the segment 61 was set to 3 mm, starting from a radius of 5 mm in the variable height section (section (2)) of the segment 61. In addition, in each embodiment, 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 varied from 4 mm to 10 mm.

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

[0385] Figure 10c is a graph showing the results of counting the number of layered 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 relative to the core center, and the vertical axis represents the number of layered segments counted at each radial point. The same applies to Figures 10d and 10e, which will be described later.

[0386] Referring to Figure 10c, the uniform number of stacked segments interval b1 appears in common in Examples 1-1 to 1-7 and Comparative Example 1. The uniform number of stacked segments interval b1 is the radius interval of the flattened region in each graph. The length of the uniform number of stacked segments interval b1 increases as the maximum height of the segment decreases, with the uniform number of stacked segments interval b1' in the Comparative Example being the longest. On the other hand, the number of stacked segments increases as the maximum height hN of the segment increases. That is, if the maximum height hN of the segment increases and the width of the variable height interval of the segment (interval (2)) increases, the number of stacked segments increases, while the width of the uniform number of stacked segments interval b1 decreases. Outside the uniform number of stacked segments interval b1, a decreasing number of stacked segments interval b2 appears where the number of stacked segments decreases as the radius increases. The decreasing number of stacked segments interval b2 is the radius interval where the number of stacked segments decreases as the radius of the electrode assembly increases. The uniform number of stacked segments interval b1 and the decreasing number of stacked segments interval b2 are adjacent in the radial direction and are complementary to each other. In other words, if the length of one section increases, the length of the other section decreases. Also, in the section b2 where the number of layers decreases, the amount of decrease in the number of layers is proportional to the distance from the section b1 where the number of layers is uniform.

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

[0388] In Examples 1-1 to 1-7, the uniform layering section b1 begins at the radius point where the variable-height section of the segment (section (2)) begins. That is, the variable-height section (section (2)) starts at a radius of 5 mm and extends outwards.

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

[0390] The negative electrode is substantially identical to the positive electrode in all other parameters, except that it shows a difference of 0.1-1.2% with respect to parameter h. The sum of ratios h, i, and j is slightly different from 100%. This is because there is a section without a segment in the second part B3, which corresponds to the plain outer circumference of the electrode. For example, in Example 1-1, there is no segment in the second part B3, which corresponds to approximately 4% of the total length of the electrode. In Table 4, a-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 as an electrode assembly. Also, the parameters corresponding to ratios (%) are values ​​rounded to the first decimal place. This is substantially the same in Tables 5 and 6 described later. [Table 4]

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

[0392] Cylindrical batteries with form factors 1865 and 2170 have an electrode assembly radius of approximately 9mm to 10mm. Therefore, compared to conventional cylindrical batteries, it is not possible to secure a radial length of 17mm for the segment section (f) as in Examples 1-1 to 1-7, and it is not possible to secure a length of 8mm to 14mm for the uniform number of stacked segments (e) where the number of stacked segments is 10 or more. In conventional cylindrical batteries, if the core radius is designed to be 2mm, the same as in Examples 1-1 to 1-7, the radial section in which segment sections can be placed is effectively only 7mm to 8mm. In addition, in conventional cylindrical batteries, the length of the electrodes in the winding direction is in the range of 600mm to 980mm. Such short electrode lengths are only about 15% to 24% of the electrode lengths used in Examples 1-1 to 1-7 (positive electrode 3948mm, negative electrode 4045mm). Therefore, the numerical ranges for parameters h, i, and j cannot be easily derived from the design specifications of conventional cylindrical batteries.

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

[0394] The electrode assemblies of Examples 2-1 to 2-5 have a radius of 22 mm and a core diameter of 4 mm. The minimum height h1 in the height-variable section of the segment 61 (section (2) in Figure 10a) is the same as 4 mm, and the maximum height h N The width 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 width of the variable section height section (section (2) in Figure 10a) is 2 mm, 3 mm, 4 mm, 5 mm, and 6 mm, respectively, and the section omitted section (section (1) in Figure 10a) is a radius section 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 core C diameter of 4 mm. The minimum height h1 in the height-variable section of the segment 61 (section (2) in Figure 10a) is the same as 5 mm, and the maximum height h N The width was varied from 7 mm to 10 mm in 1 mm increments. Therefore, in the electrode assemblies of Examples 3-1 to 3-4, the width of the variable section height section (section (2) in Figure 10a) is 2 mm, 3 mm, 4 mm, and 5 mm, respectively, and the section omitted section (section (1) in Figure 10a) is a radius section 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 core C diameter of 4 mm. The minimum height h1 in the height-variable section of the segment 61 (section (2) in Figure 10a) is the same as 6 mm, and the maximum height h N The width was varied from 8 mm to 10 mm in 1 mm increments. Therefore, in the electrode assemblies of Examples 4-1 to 4-3, the width of the variable section height section (section (2) in Figure 10a) is 2 mm, 3 mm, and 4 mm, respectively, and the section omitted section (section (1) in Figure 10a) is a radius section from 2 mm to 8 mm.

[0397] The electrode assemblies of Examples 5-1 to 5-2 have a radius of 22 mm and a core diameter of 4 mm. The minimum height h1 in the height-variable section of the segment 61 (section (2) in Figure 10a) is the same as 7 mm, and the maximum height h N The width was varied from 9 mm to 10 mm in 1 mm increments. Therefore, in the electrode assemblies of Examples 5-1 to 5-2, the width of the variable section height section (section (2) in Figure 10a) is 2 mm and 3 mm, respectively, and the section omitted section (section (1) in Figure 10a) is a radius section from 2 mm to 9 mm.

[0398] Figure 10d is a graph showing the results of counting the number of stacked segments measured radially in the bent surface region F of the positive electrode formed on the upper part of the electrode assemblies 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. The results are substantially the same for the bent surface region of the negative electrode.

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

[0400] Referring to Figure 10d, the uniform stacking interval b1 of the subsections appears in common in all examples. The uniform stacking interval b1 is the radius interval of the flattened region in the graph. The length of the uniform stacking interval b1 is equal to the maximum height h of the subsections when the minimum height h1 of the subsections is the same. N It increases as the decrease in the number of layers decreases. Also, the length of the uniform layering interval b1 is equal to the maximum height of the subsection h. N When these are the same, the number of layers of the subsection increases as the minimum height h1 of the subsection decreases. On the other hand, in the uniform layering interval b1, the number of layers of the subsection is equal to the maximum height h of the subsection. N The value increases as the value increases. In the example, a section b2 with a decreasing number of layers appears adjacent to a section b1 with a uniform number of layers.

[0401] In the example, the number of layers of the segment in the uniform layer number section b1 is 10 or more in all cases. The region where the number of layers of the segment is 10 or more can be set as a desirable welding target region.

[0402] In the examples, the uniform layering section b1 starts from the radius point where the variable height section of the segment (section (2) in Figure 10a) begins. In Examples 2-1 to 2-5, the variable height section of the segment (section (2) in Figure 10a) starts at 6 mm and extends outwards. In Examples 3-1 to 3-4, the variable height section of the segment (section (2) in Figure 10a) starts at 7 mm and extends outwards. In Examples 4-3 to 4-3, the variable height section of the segment (section (2) in Figure 10a) starts at 8 mm and extends outwards. In Examples 5-1 and 5-2, the variable height section of the segment (section (2) in Figure 10a) starts at 9 mm and extends outwards.

[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 layer count section to the length from the radius point where the uniform layer count section begins (6mm, 7mm, 8mm, 9mm) to the outermost point of the electrode assembly (22mm), and the ratio (d / f) of the length of the variable segment height section (section (2)) to the length from the radius point where the uniform layer count section begins (6mm, 7mm, 8mm, 9mm) to the outermost point of the electrode assembly (22mm). [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)) is the same at 10 mm, but the minimum height h1 of the segment increases by 1 mm each time, from 4 mm, 5 mm, 6 mm, to 7 mm, and the length of the variable height section (section (2)) decreases by 1 mm each time, from 6 mm, 5 mm, 4 mm, to 3 mm. In the four examples, the ratio (e / f) of the uniform number of layers section is highest in Example 2-5 at 69% and lowest in Example 5-2 at 38%, and the number of layers in the uniform number of layers section is the same in all examples. From the results shown in Table 5, the maximum height h of the segment N When these values ​​are the same, it can be seen that as the minimum height h1 of the subsection decreases and the width of the variable height subsection section (section (2)) increases, the width of the uniform stacking section also increases proportionally. The reason for this is that the smaller the minimum length h1 of the subsection, the closer the radius point where the subsection begins is to the core, and the region where the subsections are stacked expands towards the core.

[0405] Referring to Table 5, it can be seen that the number of layers of segmentation segments ranges from 16 to 26, the ratio (d / f) of the segmentation segment with variable height (section (2)) is 13% to 38%, and the ratio (e / f) of the segment with a uniform number of layers is 31% to 69%. Furthermore, the ratio (c / (ba)) of the segmentation segment omitted section (section (1)) to the radius (ba) of the electrode assembly excluding the core is 20% to 35%. In addition, the ratio of the length of the electrode region corresponding to the segmentation segment omitted section (section (1)) to the total 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 total length of the electrode is 6% to 25%, and the ratio of the length of the electrode region corresponding to the height-uniform section (section (3)) to the total length of the electrode is 62% to 81%.

[0406] Cylindrical batteries with form factors 1865 and 2170 have an electrode assembly radius of approximately 9mm to 10mm. Therefore, as in the embodiment, it is not possible to secure a radial length of 13mm to 16mm for the segment section (f), and it is not possible to secure a length of approximately 4mm to 7mm for the segment omitted section (c, section (1)) while simultaneously securing a length of 5mm to 11mm for the uniform number of stacked segments (e), where the number of stacked segments is 10 or more. In conventional cylindrical batteries, if the core radius is designed to be the same as in the embodiment (2mm), the radial section in which segment sections can be placed is effectively only 7mm to 8mm. Furthermore, in conventional cylindrical batteries, the length of the electrodes in the winding direction is approximately 600mm to 980mm. Such short electrode lengths are only about 15% to 24% of the electrode lengths in the embodiment (positive electrode 3948mm, negative electrode 4045mm). Therefore, the numerical ranges for parameters h, i, and j cannot be easily derived from the design specifications of conventional cylindrical batteries.

[0407] Next, in the section with variable segment height (section (2)), the minimum height h1 and maximum height h N When the core diameter C of the electrode assembly is the same, we will explain, with specific examples, how the number of stacked segments changes along the radial direction of the bent surface region F depending on the core diameter C of the electrode assembly.

[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 in the height-variable section (section (2)) of segment 61 is the same as 3 mm, and the maximum height h N The width was varied from 5 mm to 10 mm in 1 mm increments. Therefore, in the electrode assemblies of Examples 6-1 to 6-6, the width of the variable section height section (section (2)) is 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, and 7 mm, respectively, and the section omitted section (section (1)) is a radius section 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 in the height-variable section (section (2)) of segment 61 is the same as 3 mm, and the maximum height h N The width was varied from 5 mm to 10 mm in 1 mm increments. Therefore, in the electrode assemblies of Examples 7-1 to 7-6, the width of the variable section height section (section (2)) is 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, and 7 mm, respectively, and the section omitted section (section (1)) is the same as the radius section from 2 mm to 5 mm.

[0410] Figure 10e is a graph showing the results of counting the number of stacked segments measured along the radial direction in the bent 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 Examples 7-1 to 7-6. Substantially the same results are observed in the bent surface region of the negative electrode.

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

[0412] Referring to Figure 10e, the uniform stacking interval b1 of the subsections appears in common in all examples. The uniform stacking interval b1 is the radial interval of the flattened region in the graph. The radial length of the uniform stacking interval b1 is equal to the maximum height h of the subsections when the minimum height h1 of the subsections is the same. N The number of layers increases as the decrease in the number of layers decreases. On the other hand, in the uniform layering interval b1, the number of layers of the subsection is equal to the maximum height of the subsection h. N The value increases as the value increases. In the example, a section b2 with a decreasing number of layers is observed adjacent to a section b1 with a uniform number of layers.

[0413] In the example, the number of layers of the segment in the uniform layer number section b1 is 10 or more in all cases. The region where the number of layers of the segment is 10 or more can be set as a desirable welding target region.

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

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

[0416] Referring to Figure 10a and Examples 6-6 and 7-6 in Table 6, the minimum height h1 and maximum height h of the segment in the segment height variable section (section (2)) NThese are the same at 3 mm and 10 mm, respectively. However, the core radius of Example 6-6 is 2 mm larger than that of Example 7-6. Therefore, in Example 6-6, the uniform number of layers section (e) and the segment section (f) are 2 mm smaller than in Example 7-6, while the number of layers of segment sections in the uniform number of layers 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 height-variable section of segment sections (section (2)) is the same, the smaller the core radius (a), the smaller the ratio (d / f) of the height-variable section (section (2)), while the ratio (e / f) of the uniform number of layers section increases. Referring to Table 6, it can be seen that the number of layers of segment sections is 13 to 26, the ratio (d / f) of the height-variable section of segment sections (section (2)) is 12% to 47%, and the ratio (e / f) of the length of the uniform number of layers section is 40% to 76%. Furthermore, the ratio (c / (ba)) of the segment omission section (section (1)) to the radius (ba) of the electrode assembly excluding the core is 15% to 17%. Also, the ratio of the length of the electrode region corresponding to the segment omission section (section (1)) to the total 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 total 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 total length of the electrode is 59% to 83%.

[0417] Cylindrical batteries with form factors 1865 and 2170 have an electrode assembly radius of approximately 9 mm to 10 mm. Therefore, as in the embodiment, it is not possible to secure a radial length of 15 mm to 17 mm for the segment section (f), and it is not possible to secure a length of approximately 3 mm for the segment omitted section (section (1)) while simultaneously securing a length of 6 mm to 13 mm for the uniform number of stacked sections (e), where the number of stacked segments is 10 or more. In conventional cylindrical batteries, if the core radius is designed to be the same as in the embodiment (2 mm to 4 mm), the radial section in which segment sections can be placed is effectively only 5 mm to 8 mm. Furthermore, in conventional cylindrical batteries, the length of the electrodes in the winding direction is approximately 600 mm to 980 mm. Such short electrode lengths are only about 15% to 24% of the electrode lengths in the embodiment (positive electrode 3948 mm, negative electrode 4045 mm). Therefore, the numerical ranges for 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 layers of segmental segments in the uniform segmental segmental segment section can be 11 to 26. Also, the ratio (d / f) of the segmental segmental segment with variable height (section (2)) can be 6% to 47%. Also, the ratio (e / f) of the uniform segmental segmental segment can be 31% to 82%. Also, the ratio (c / (ba)) of the length of the segmental segmental segment omitted section (section (1)) to the radius of the electrode assembly excluding the core can be 15% to 35%. Also, the ratio of the length of the electrode region corresponding to the segmental segmental segment omitted section (section (1)) to the total length of the electrode (length in the winding direction) can be 6% to 20%. Also, the ratio of the length of the electrode region corresponding to the segmental segmental segment with variable height (section (2)) to the total length of the electrode can be 3% to 32%. Also, the ratio of the length of the electrode region corresponding to the segmental segmental segment with uniform height (section (3)) to the total length of the electrode can be 59% to 87%.

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

[0420] Therefore, the number of stacked segments in the uniform number of segmented segments section can be extended from 10 to 35. The ratio (d / f) of the variable height segmented segmented segment (section (2)) can be extended from 1% to 50%. The ratio (e / f) of the uniform number of stacked segments can be extended from 30% to 85%. The ratio (c / (ba)) of the length of the segmented segment omitted section (section (1)) to the radius of the electrode assembly excluding the core can be extended from 10% to 40%. The ratio of the length of the electrode region corresponding to the segmented segment omitted section (section (1)) to the total length of the electrode (length in the winding direction) can be extended from 1% to 30%. The ratio of the length of the electrode region corresponding to the variable height segmented segmented segment (section (2)) to the total length of the electrode can be extended from 1% to 40%. The ratio of the length of the electrode region corresponding to the uniform height segmented segmented segment (section (3)) to the total length of the electrode can be extended from 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)) N The height index N is 2 to 8. For example, referring to Table 4, the height index N for Example 1-1 and Example 1-7 are 2 and 8, respectively. However, the height index N can vary depending on the change in height Δh of the segmental section in the radial direction of the electrode assembly. When the radial length of the height-variable section (section (2)) is fixed, a decrease in the change in height Δh of the segmental section increases the height index N, and vice versa is also possible. Preferably, the height index N is 2 to 20, and optionally, it can be further extended to 2 to 30.

[0421] In the bent surface regions F formed on the upper and lower parts of the electrode assembly, the uniform layer count section can be used as a welding target region for the current collector.

[0422] Preferably, the welding area of ​​the current collector overlaps with the uniform layer number section of the electrode assembly by at least 50% in the radial direction, and a higher overlap ratio is even more desirable.

[0423] Preferably, other regions of the current collector's welding area that do not overlap with the uniform layer count section may overlap with the radially adjacent layer count reduction section.

[0424] More preferably, other regions of the current collector's welding area that do not overlap with the uniform layer count section may overlap with regions of the decreasing layer count section where the number of overlapping segments is 10 or more.

[0425] Welding a current collector to a region with 10 or more layers of segmentation is desirable in terms of weld strength and the ability to prevent damage to the separation film and active material layer during welding. This is particularly useful when welding a current collector using a high-power laser with high transmission characteristics.

[0426] When a current collector is welded with a laser to a section with a uniform number of layers, where 10 or more sections are stacked, even if the laser output is increased to improve welding quality, the section with a uniform number of layers absorbs almost all of the laser energy and forms weld beads. This prevents the separation film and active material layer below the bent surface region F from being damaged by the laser.

[0427] Furthermore, because the laser-irradiated area has 10 or more layers of segmented material, welding beads are formed with sufficient volume and thickness. Therefore, sufficient welding strength is ensured, and the resistance at the welding interface can be reduced to a level suitable for rapid charging.

[0428] The laser output during welding of the current collector can be determined by the desired welding strength between the bent surface region F and the current collector. The welding strength increases proportionally to the number of layers of segmentation. This is because the volume of welding beads formed by the laser increases as the number of layers increases. Welding beads are formed as the current collector material and the segmentation material are melted together. Therefore, a larger volume of welding beads results in a stronger bond between the current collector and the bent surface region, and a lower contact resistance at the welding interface.

[0429] Ideally, the weld strength should be 2 kgf / cm². 2 More preferably, 4 kgf / cm² 2 The above is possible. The maximum weld strength may vary depending on the output of the laser welding equipment. As an example, the weld strength is preferably 8 kgf / cm². 2 The following is more preferable: 6 kgf / cm² 2 The following settings may be used. However, the present invention is not limited thereto.

[0430] If the welding strength meets the above numerical range, the physical properties of the weld interface will not deteriorate even if the electrode assembly is subjected to severe vibration along the winding axis and / or radial direction, and the resistance of the weld interface can also be reduced because the volume of welding beads is sufficient.

[0431] The laser power 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 power specification provided by the device.

[0432] Weld strength is the tensile force per unit area (kgf / cm²) of the current collector at which the current collector begins to separate from the bent surface region F. 2 It can be defined as follows: Specifically, after the welding of the current collector is completed, a tensile force is applied to the current collector, and its magnitude is gradually increased. When the tensile force exceeds a critical value, the intercepts begin to separate from the weld interface. At this point, the value obtained by dividing the tensile force applied to the current collector by the area of ​​the current collector corresponds to the weld strength.

[0433] The bent surface region F is composed of multiple layers of segmented sections, and according to the embodiment described above, the number of layered segmented sections 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 plain portion 43 is 10 μm to 25 μm, and the thickness of the negative electrode current collector (foil) constituting the plain 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 stacking thickness of the segmented pieces is 100 μm to 875 μm. Also, the folded surface region F of the negative electrode may include a region where the total stacking thickness of the segmented pieces is 50 μm to 700 μm.

[0435] Figure 10f is a top view of an electrode assembly showing a uniform layer number section b1 and a decreasing layer number section b2 in the folded surface region F of the section 61 and 61' according to an embodiment of the present invention.

[0436] Referring to Figure 10f, the region between the two circles shown by the thick solid line corresponds to the folded surface region F of the segment, the region between the two circles shown by the dashed line corresponds to the uniform layer number section b1 where the number of layers of the segment is 10 or more, and the region outside the uniform layer number section b1 corresponds to the decreasing layer number section b2.

[0437] As an example, current collector P c If it is welded to the bent surface region F, the current collector P c Weld pattern W on the surface p This is generated. Weld pattern W p This can be an array of line patterns or dot patterns. Welding pattern W p This corresponds to the welding area and can overlap by 50% or more with the uniform layer number section b1 along the radial direction. Therefore, welding pattern W p A portion of the weld pattern is included in the uniform layer number section b1, and the remaining weld pattern W p This may be included in the layer count reduction section b2 outside the uniform layer count section b1. Of course, in order to maximize welding strength and reduce the resistance of the welding area, the welding pattern W p The entire structure can overlap with the uniform layering interval b1.

[0438] The area of ​​the folded surface region F can be defined as the sum of the area of ​​the uniform layer number section b1 and the area of ​​the decreasing layer number section b2 of the segment. Since the ratio (e / f) of the uniform layer number section b1 is 30% to 85%, preferably 31% to 82%, the ratio of the area of ​​the uniform layer 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, current collector P c The ends of the portion that contacts the bent surface region F may cover the ends of the segment 61, 61' that are bent towards the core C in the last winding turn of the uniform height section (section (3)). In this case, the segment 61, 61' cover the current collector P c Weld pattern W while pressed down p As a result of the formation of the current collector P c The folded surface region F is strongly bonded to the weld surface region. As a result, the segmented sections 61 and 61' stacked in the winding axis direction are tightly bonded to each other, which reduces the resistance at the welding interface and prevents the segmented sections 61 and 61' from lifting up.

[0440] On the other hand, the bending direction of the segment may be opposite to the direction described above. That is, the segment may be bent from the core side to the outer circumference side. In this case, the pattern in which the height of the segment changes along the winding direction (X-axis direction) may be opposite to that of the above-described embodiment (modification). For example, the height of the segment may decrease in stages from the core to the outer circumference side. Also, the structure applied to the first part B1 and the structure applied to the second part B3 may be switched. Preferably, the height change pattern of the segment may be designed so that the height of the segment decreases in stages from the core side to the outer circumference side, and when the segment closest to the outer circumference of the electrode assembly is bent to the outer circumference side, the end of the segment does not protrude outside the outer circumference of the electrode assembly.

[0441] The electrode structure of the above-described embodiment (modified version) can be applied to at least one of a first electrode and a second electrode with 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 (modified version) is applied to one of the first electrode and the second electrode, a conventional electrode structure may be applied to the other. In addition, the electrode structures applied to the first electrode and the second electrode may not be the same and may be different from each other.

[0442] For example, when the first electrode and the second negative electrode are the positive electrode and the negative electrode, respectively, one of the examples (modified versions) may be applied to the first electrode, and a conventional electrode structure (see Figure 1) may be applied to the second electrode.

[0443] As another example, when the first electrode and the second negative electrode are a positive electrode and a negative electrode, one of the embodiments (modified versions) may be selectively applied to the first electrode, and one of the embodiments (modified versions) 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 can be any active material known in the industry without limitation.

[0445] For example, the positive electrode active material is a material with the general chemical formula A(A x M y )O 2+z The compound may include alkali metal compounds represented as (A contains at least one element from Li, Na, and K; M contains 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; stoichiometric counts x, y, and z are selected so that the compound maintains electrical neutrality).

[0446] As another example, the positive electrode active material is an alkali metal compound xLiM disclosed in U.S. Patent No. 6,677,082, U.S. Patent 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; and 0 ≦ x ≦ 1).

[0447] As yet another example, the positive electrode active material has the general 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[[ID=二十九]] 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 Li3M (PO4) 3 [M contains at least one element selected from Ti, Si, Mn, Fe, Co, V, Cr, Mo, Ni, Al, Mg, and Al].[[ID=三十一]]

[0448] Desirably, the positive electrode active material may include primary particles and / or secondary particles formed by aggregating the primary particles.

[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. may be used. Metal oxides such as TiO2 and SnO2 having 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] As the separation membrane, porous polymer films, such as those made from polyolefin polymers like ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer, or ethylene / methacrylate copolymer, can be used alone or in laminated form. As another example, the separation membrane can be made from ordinary porous nonwoven fabrics, such as nonwoven fabrics made from high-melting-point glass fibers or polyethylene terephthalate fibers.

[0451] The separation membrane may include a coating layer of inorganic particles on at least one surface. Alternatively, the separation membrane itself may consist of a coating layer of inorganic particles. The particles constituting the coating layer may have a structure in which they are bound to a binder such that an interstitial volume exists between adjacent particles.

[0452] Inorganic particles may consist of inorganic materials with a dielectric constant of 5 or more. As an unrestricted example, the inorganic particles may be Pb(Zr,Ti)O3(PZT), Pb 1-x La x Zr 1-y Ti y O3(PLZT), PB(Mg3Nb) 2 / 3 It may contain at least one substance selected from the group consisting of O3-PbTiO3(PMN-PT), BaTiO3, hafnia (HfO2), SrTiO3, TiO2, Al2O3, ZrO2, SnO2, CeO2, MgO, CaO, ZnO, and Y2O3.

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

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

[0455] The electrode assembly 80 can be manufactured by the winding method described with reference to Figure 2. For the sake of explanation, the protruding structures of the first blank portion 43a and the second blank portion 43b extending to the outside of the separation membrane are shown in detail, while the illustration of the winding structure of the first electrode, the second electrode, and the separation membrane is omitted. The first blank portion 43a protruding upward is an extension from the first electrode, and the second blank portion 43b protruding downward is an extension from the second electrode.

[0456] The patterns of how the heights of the first blank section 43a and the second blank section 43b change are schematically illustrated. That is, the height of the blank section can change irregularly depending on the cutting position of the cross section. For example, if the sides of the trapezoidal subsections 61 and 61' or the cutting groove 63 are cut, the height of the blank section in the cross section will be lower than the height H of the subsections 61 and 61'. Therefore, the height of the blank section shown in the drawing of the cross section of the electrode assembly must be understood to correspond to the average height of the blank section included in each winding turn (H in Figures 7b and 8b).

[0457] Referring to Figure 11, the first blank 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 section B3 is relatively lower than the height of the third section B2. Therefore, it is possible to prevent the phenomenon of an internal short circuit occurring when the beading section of the battery housing comes into contact with the second section B3 during the process in which the beading section is pressurized near the second section B3.

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

[0460] The ends 81 of the first blank portion 43a and the ends 81 of the second blank portion 43b can be bent radially from the electrode assembly 80, for example, from the outer circumference to the core. In this case, the second portion B3 does not need to be bent substantially.

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

[0462] Referring to Figure 12, the first blank 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 section B3 is relatively lower than the height of the third section B2, and decreases gradually or in steps from the core side to the outer circumference. Therefore, it is possible to prevent the phenomenon of an internal short circuit occurring when the beading section of the battery housing comes into contact with the second section B3 during the process in which the beading section is pressurized near the second section B3.

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

[0465] The ends 91 of the first blank portion 43a and the ends 91 of the second blank portion 43b can be bent radially from the electrode assembly 90, for example, from the outer circumference to the core. In this case, the outermost part 92 of the second portion B3 does not need to be bent substantially.

[0466] Figure 13 is a cross-sectional view of a jelly roll-type electrode assembly 100, cut along the Y-axis direction (winding axis direction), in which one of the electrodes 50, 60, or 70 from the third to fifth embodiments (and their variations) is applied as the first electrode (positive electrode) and the second electrode (negative electrode).

[0467] Referring to Figure 13, the plain 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 part B1 is relatively lower than the height of the third part B2. Also, in the third part B2, the fold length of the innermost plain section 43a is the same as or shorter than the radial length R of the first part B1. The fold length H corresponds to the distance from the point where the plain section 43a is folded to the upper end of the plain section 43a. In the modified example, the fold length H may be smaller than the sum of the radial length R of the first part B1 and 10% of the radius of the core 102.

[0469] Therefore, even if the third part B2 is bent, more than 90% of the diameter of the core 102 of the electrode assembly 100 remains open to the outside. The core 102 is a cavity at the center of the electrode assembly 100. If the core 102 is not blocked, the electrolyte injection process is not hindered, and the efficiency of electrolyte injection is improved. In addition, a welding jig can be inserted through the core 102 to facilitate the welding process between the negative electrode (or positive electrode) current collector and the battery housing (or terminal).

[0470] The height of the second section B3 is relatively lower than the height of the third section B2. Therefore, it is possible to prevent the phenomenon of an internal short circuit occurring when the beading section of the battery housing comes into contact with the second section B3 during the process in which the beading section is pressurized near the second section B3.

[0471] In one modified example, the height of the second section B3 may decrease gradually or in stages, unlike in the illustration in Figure 13. Also, in Figure 13, the height of the third section B2 is equal in a portion of the outer perimeter, but the height of the third section B2 may increase gradually or in stages from the boundary between the first section B1 and the third section B2 to the boundary between the third section B2 and the second section B3. When the third section B2 is divided into multiple subsections, the section in which the height of the plain area 43a changes corresponds to the section with variable height (section (2) in Figure 10a).

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

[0473] The ends 101 of the first blank portion 43a and the second blank portion 43b can be bent radially from the electrode assembly 100, for example, from the outer circumference to the core. In this case, the first portion B1 and the second portion B3 are not substantially bent.

[0474] When the third section B2 includes multiple subsections, the bending stress is relieved, preventing the plain section 43a near the bending point from tearing or deforming abnormally. Furthermore, when the width and / or height and / or spacing pitch of the subsections are adjusted within the numerical range of the above-described embodiment, the subsections overlap in sufficient quantities to ensure sufficient welding strength while bending toward the core, without forming any gaps in the bending surface region.

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

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

[0477] Part B3 of the second section may include multiple segments. The configuration of the multiple segments is substantially the same as that of the fourth and fifth embodiments (modified versions) relating to electrodes.

[0478] In the electrode assembly 110, the height of the first portion B1 is relatively lower than the height of the third portion B2. Also, the fold length H of the plain portion located on the innermost side of the third portion B2 is the same as or shorter than the radial length R of the first portion B1. Preferably, the first portion B1 may be a segment-omitted section (section (1) in Figure 10a) where no segment segments exist. In a modified example, the fold 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, more than 90% of the diameter of the core 112 of the electrode assembly 110 remains open to the outside. If the core 112 is not blocked, the electrolyte injection process is not hindered, and the efficiency of electrolyte injection is improved. Furthermore, a welding jig can be inserted through the core 112 to facilitate the welding process between the negative electrode (or positive electrode) current collector and the battery housing (or terminal).

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

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

[0482] The ends 111 of the first blank section 43a and the second blank section 43b can be bent radially from the electrode assembly 110, for example, from the outer circumference to the core. In this case, the first section B1 is not substantially bent.

[0483] When the third part B2 and the second part B3 include multiple subsections, the bending stress is relieved, preventing the plain sections 43a and 43b near the bending point from tearing or deforming abnormally. Furthermore, when the width and / or height and / or spacing pitch of the subsections are adjusted within the numerical range of the above-described embodiment, the subsections overlap in sufficient quantities to ensure sufficient welding strength while bending toward the core, without forming any gaps in the bending surface region.

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

[0485] Referring to Figure 15, the electrode assembly 120 is substantially identical to the electrode assembly 100 in Figure 13, except that the height of the third portion B2 has a pattern in which it gradually or stepwise increases and then decreases. The radial section in which the height of the third portion B2 changes can be considered as the variable height section of the segment (section (2) in Figure 10a). In this case as well, the variable height section of the segment can be designed such that in the bent surface region F formed as the third portion B2 is bent, a uniform stacking section with 10 or more stacking sections appears within the desired numerical range described above.

[0486] Such height variations in the third section B2 can be realized by adjusting the height of the step pattern (see Figure 6) or the segment (see Figure 7a or Figure 8a) included in the third section B2.

[0487] In the electrode assembly 120, the height of the first part B1 is relatively lower than the height of the third part B2. Also, the fold length H of the plain section located on the innermost side of the third part B2 is the same as or shorter than the radial length R of the first part B1. The section corresponding to the first part B1 corresponds to the section without a subsection (section (1) in Figure 10a). In the modified example, the fold length H may be smaller than the sum of the radial length R of the first part B1 and 10% of the radius of the core 122.

[0488] Therefore, even if the third portion B2 is bent toward the core, the core 122 of the electrode assembly 120 remains open to the outside by more than 90% of its diameter. If the core 122 is not blocked, the electrolyte injection process is not hindered, and the efficiency of electrolyte injection is improved. Furthermore, a welding jig can be inserted through the core 122 to facilitate the welding process between the negative electrode (or positive electrode) current collector and the battery housing (or terminals).

[0489] Furthermore, the height of the second portion B3 is relatively lower than the height of the third portion B2, and preferably, no segment may be formed in the second portion B3. Therefore, it is possible to prevent the phenomenon of an internal short circuit occurring when the beading portion of the battery housing comes into contact with the second portion B3 during the process in which the beading portion of the battery housing is pressurized near the second portion B3. In one modified example, the height of the second portion B3 may decrease gradually or in steps toward the outer circumference.

[0490] The second blank portion 43b has the same structure as the first blank portion 43a. In modified examples, the second blank portion 43b may have a conventional electrode structure or an electrode structure of other embodiments (modified examples).

[0491] The end 121 of the first blank section 43a and the end 121 of the second blank section 43b can be bent from the outer circumference side of the electrode assembly 120 toward the core side. In this case, the first section B1 and the second section B3 are not substantially bent.

[0492] If the third section B2 includes multiple subsections, the bending stress can be relieved, preventing the plain sections 43a and 43b from tearing or deforming abnormally. Furthermore, if the width and / or height and / or spacing pitch of the subsections are adjusted within the numerical range of the above-described embodiment, the subsections will overlap in sufficient quantities while bending toward the core, ensuring sufficient welding strength and preventing the formation of gaps in the bent surface region.

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

[0494] Referring to Figure 16, the electrode assembly 130 is different from the electrode assembly 120 in Figure 15. The height of part B3 is from the boundary point between part B3 and part B2 to the top of electrode assembly 130. Except for having a pattern that gradually or gradually decreases toward the outer surface, the other configuration They are essentially identical.

[0495] Such a change in the height of the second part B3 can be realized by extending the step pattern included in the third part B2 (see Figure 6) to the second part B3, while simultaneously gradually or stepwise decreasing the height of the pattern toward the outer periphery. In other modifications, the change in the height of the second part B3 can also be realized by extending the segment structure of the third part B2 to the second part B3, while simultaneously gradually or stepwise decreasing the height of the segment toward the outer periphery.

[0496] In the electrode assembly 130, the height of the first part B1 is relatively lower than the height of the third part B2. Also, the fold length H of the plain section located on the innermost side of the third part B2 is the same as or shorter than the radial length R of the first part B1. The first part B1 corresponds to a segment omission section (section (1) in Figure 10a) where no segment segments exist. In the modified example, the fold length H may be smaller than the sum of the radial length R of the first part B1 and 10% of the radius of the core 132.

[0497] Therefore, even if the third portion B2 is bent toward the core, more than 90% of the diameter of the core 132 of the electrode assembly 130 remains open to the outside. If the core 132 is not blocked, the electrolyte injection process is not hindered, and the efficiency of electrolyte injection is improved. Furthermore, a welding jig can be inserted through the core 132 to facilitate the welding process between the negative electrode (or positive electrode) current collector and the battery housing (or terminal).

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

[0499] The end 131 of the first blank section 43a and the end 131 of the second blank section 43b can be bent from the outer circumference side of the electrode assembly 130 toward the core side. In this case, the first section B1 is not substantially bent.

[0500] When the third part B2 and the second part B3 include multiple subsections, the bending stress is relieved, preventing the plain sections 43a and 43b near the bending point from tearing or deforming abnormally. Furthermore, when the width and / or height and / or spacing pitch of the subsections are adjusted within the numerical range of the above-described embodiment, the subsections overlap in sufficient quantities to ensure sufficient welding strength while bending toward the core, without forming any gaps in the bending surface region.

[0501] On the other hand, in the above-described embodiment (modified version), the ends of the first blank portion 43a and the second blank portion 43b may be bent from the core side to the outer circumference. In this case, it is desirable that the second portion B3 is designed as a segment-omitted section (section (1) in Figure 10a) where no segment segments exist, and is not bent to the outer circumference. Also, the radial width of the second portion B3 may be the same as or greater than the length to which the outermost blank portion (or segment segment) of the third portion B2 is bent. This prevents the end of the bent portion from protruding beyond the outer surface of the electrode assembly toward the inner surface of the battery housing when the outermost blank portion (or segment segment) of the third portion B2 is bent toward the outer circumference. Furthermore, the pattern of change in the segment segment structure may be the opposite of that in the above-described embodiment (modified version). For example, the height of the segment segment may increase stepwise or gradually from the core side toward the outer circumference. In other words, by arranging sections with omitted segments (section (1) in Figure 10a), sections with variable segment height (section (2) in Figure 10a), and sections with uniform segment height (section (3) in Figure 10a) in order from the outer circumference of the electrode assembly toward the core, it is possible to make sections with a uniform number of layers, where the number of layered segments is 10 or more, appear in the folded surface region within a desirable numerical range.

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

[0503] Preferably, a cylindrical battery may be one in which the form factor ratio (defined as the ratio of the diameter to the height of the cylindrical battery, i.e., the ratio of height (H) to relative diameter (Φ)) is greater than approximately 0.4. Here, the form factor refers to the values ​​indicating 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 a cylindrical battery according to one embodiment may be, for example, 46110, 4875, 48110, 4880, or 4680. In the numerical representation of 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 with a tabless structure is applied to a cylindrical battery with a form factor ratio exceeding 0.4, the stress applied radially when bending the plain section is large, making the plain section prone to tearing. Furthermore, when welding a current collector to the bent surface region of the plain section, the number of layers of the plain section in the bent surface region must be sufficiently increased in order to ensure sufficient welding strength and reduce resistance. These requirements can be met by the electrode and electrode assembly according to the embodiment (modification) of the present invention.

[0506] An embodiment of the present invention may be a cylindrical battery that is substantially cylindrical in shape, having a diameter of approximately 46 mm, a height of approximately 110 mm, and a form factor ratio of 0.418.

[0507] The battery according to another embodiment may be a cylindrical battery that is roughly cylindrical in shape, with a diameter of approximately 48 mm, a height of approximately 75 mm, and a form factor ratio of 0.640.

[0508] Furthermore, another embodiment of the battery may be a cylindrical battery that is roughly cylindrical in shape, with a diameter of approximately 48 mm, a height of approximately 110 mm, and a form factor ratio of 0.436.

[0509] Furthermore, a battery according to another embodiment may be a cylindrical battery that is roughly cylindrical in shape, with a diameter of approximately 48 mm, a height of approximately 80 mm, and a form factor ratio of 0.600.

[0510] Furthermore, another embodiment of the battery may be a cylindrical battery that is roughly cylindrical in shape, with a diameter of approximately 46 mm, a height of approximately 80 mm, and a form factor ratio of 0.575.

[0511] Traditionally, 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. An 1865 battery has a diameter of approximately 18mm, a height of approximately 65mm, and a form factor ratio of 0.277. A 2170 battery has a diameter of approximately 21mm, a height of approximately 70mm, and a form factor ratio of 0.300.

[0512] A cylindrical battery according to one embodiment of the present invention will be described in detail below.

[0513] Figure 17 is a cross-sectional view of a cylindrical battery 140 according to one embodiment of the present invention, cut along the Y-axis.

[0514] Referring to Figure 17, a cylindrical battery 140 according to one embodiment of the present invention includes an electrode assembly 141 comprising a first electrode, a separator membrane, and a second electrode, a battery housing 142 housing the electrode assembly 141, and a sealant 143 sealing the open end of the battery housing 142.

[0515] The battery housing 142 is a cylindrical container with an opening formed at the top. The battery housing 142 is made of a conductive metallic material such as aluminum, steel, or stainless steel. The battery housing 142 may have a nickel coating layer formed on its surface. The battery housing 142 houses the electrode assembly 141 in its inner space through the upper opening, and also houses the electrolyte together with it.

[0516] Electrolytes are, A + B - It can be a salt with a structure like this. Here, A + Li + na + , K + It contains alkali metal cations such as, or ions consisting of combinations thereof. And, B - 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 - It contains one or more anions selected from the group consisting of the following.

[0517] Furthermore, electrolytes can be used after being dissolved in an organic solvent. Suitable organic solvents include 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 mixtures thereof.

[0518] The electrode assembly 141 may have a jelly-roll structure, but the present invention is not limited thereto. The electrode assembly 141 can be manufactured by winding a laminate formed by sequentially stacking a lower separation membrane, a first electrode, an upper separation membrane, and a second electrode at least once, with respect to a winding shaft C, as shown in Figure 2.

[0519] The first electrode and the second electrode have different polarities. That is, if one has positive polarity, the other has negative polarity. At least one of the first electrode and the second electrode may have the electrode structure according to the embodiment (modification) described above. The other of the first electrode and the second electrode may have a conventional electrode structure or the electrode structure according to the embodiment (modification). The electrode assembly 141 is not limited to one electrode pair, but may have two or more.

[0520] The first blank portion 146a of the first electrode and the second blank portion 146b of the second electrode protrude from the upper and lower parts of the electrode assembly 141, respectively. The first electrode has the electrode structure of the first embodiment (modified). Therefore, the height of the second portion B3 of the first blank portion 146a is lower than the height of the blank portions of the other parts. The second portion B3 is separated from the inner circumferential surface of the battery housing 142, particularly the beading portion 147, by a predetermined distance. Therefore, the second portion B3 of the first electrode does not come into contact with the battery housing 142 which is electrically connected to the second electrode, and an internal short circuit of the cylindrical battery 140 is prevented.

[0521] The second blank portion 146b of the second electrode may have the same structure as the first blank portion 146a. In other modifications, the second blank portion 146b may selectively have the structure of the blank 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 that provides airtightness and insulation between the cap 143a and the battery housing 142, and a connecting plate 143c electrically and mechanically coupled 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 blank portion 146a of the first electrode and electrically insulated from the battery housing 142 through the first gasket 143b. Thus, the cap 143a can function as the first electrode terminal (e.g., 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 secured 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 projection 143d that protrudes upward from its center.

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

[0526] The battery housing 142 is provided with a beading portion 147 and a crimping portion 148 at its upper end. The beading portion 147 is formed by pressing around the outer circumferential surface of the battery housing 142. The beading portion 147 prevents the electrode assembly 141 housed inside the battery housing 142 from coming out of the upper end opening of the battery housing 142 and can also function as a support portion on which the seal 143 is placed.

[0527] The inner surface of the beading portion 147 is separated from the second portion B3 of the first electrode by a predetermined distance. More specifically, the lower end of the inner surface of the beading portion 147 is separated from the second portion B3 of the first electrode by a predetermined distance. Furthermore, because the second portion B3 is low in height, it is not substantially affected when the battery housing 142 is pushed in 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, thereby preventing partial deformation of the electrode assembly 141 and preventing internal short circuits in the cylindrical battery 140.

[0528] Preferably, if D1 is the indentation 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 point between the second portion B3 and the third portion B2, then the relationship D1 ≤ D2 may be satisfied. In this case, when the battery housing 142 is pressed in to form the beading portion 147, damage to the second portion B3 is substantially prevented.

[0529] The crimping portion 148 is formed on the upper part of the beading portion 147. The crimping portion 148 has a shape that extends and bends to enclose the outer circumferential surface of the cap 143a, which is positioned on the beading portion 147, and a portion 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 metallic material such as aluminum, copper, steel, or nickel, and is electrically connected to the first blank 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 coupling plate 143c, or it 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 can be formed integrally 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 arranged protrusions (not shown) on its lower surface. If radial protrusions are provided, the first current collector 144 can be pressed against the protrusions to press the first blank portion 146a of the first electrode into the protrusions.

[0534] The first current collector 144 is coupled to the end of the first blank portion 146a. The coupling between the first blank portion 146a and the first current collector 144 can be performed, for example, by laser welding. Laser welding can be performed in a manner that partially melts the base material of the first current collector 144. In a modified example, the welding between the first current collector 144 and the first blank portion 146a can be performed with solder interposed. In this case, the solder may have a lower melting point than the first current collector 144 and the first blank portion 146a. Laser welding can be replaced by resistance welding, ultrasonic welding, spot welding, etc.

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

[0536] The plain sections 146a and 146b are not limited to the illustrated structures. Therefore, the plain sections 146a and 146b may selectively have not only the conventional plain section structure but also the plain section structure of the electrode according to the embodiment (modified version).

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

[0538] The insulator 146 is provided with a lead hole 151 through which a 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 connecting plate 143c or the lower surface of the cap 143a.

[0539] The peripheral region of the insulator 146 is interposed between the first current collector 144 and the beading portion 147, and can fix the connection between the electrode assembly 141 and the first current collector 144. As a result, the movement of the connection between the electrode assembly 141 and the first current collector 144 in the winding axis direction (Y axis direction) of the cylindrical battery 140 is restricted, and the assembly stability of the cylindrical battery 140 can be improved.

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

[0541] The battery housing 142 may further include a venting section 152 formed on its lower surface. The venting section 152 corresponds to a region on the lower surface of the battery housing 142 that is thinner than the surrounding area. The venting section 152 is structurally weaker than the surrounding area. Therefore, if an abnormality occurs in the cylindrical battery 140 and the internal pressure increases above a certain level, the venting section 152 may rupture, and the gas generated inside the battery housing 142 may be discharged to the outside. The internal pressure at which the venting section 152 ruptures is approximately 15 kgf / cm². 2 ~35 kgf / cm² 2 It is possible.

[0542] The venting portion 152 may be formed continuously or discontinuously in a circular pattern on the lower surface of the battery housing 142. In a variation, the venting portion 152 may be formed in a linear pattern or other patterns.

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

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

[0545] Referring to Figure 18, the first blank portion 146a of the first electrode may be in a form in which the height of the second portion B3 gradually or stepwise decreases toward the inner surface of the battery housing 142. Preferably, a hypothetical line connecting the uppermost ends of the second portion B3 may have the same or similar shape as the inner surface of the beading portion 147.

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

[0547] The other components of the cylindrical battery 150 are substantially the same as those of the above-described embodiment (modified version).

[0548] The plain sections 146a and 146b are not limited to the illustrated structures. Therefore, the plain sections 146a and 146b may selectively have not only the conventional plain section structure but also the plain section structure of the electrode according to the embodiment (modified version).

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

[0550] Referring to Figure 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 in close contact with the lower surface 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 minimum inner diameter of the battery housing 142. Also, the diameter of the first current collector 144 may 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 location 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 location where the beading portion 147 is formed. Also, 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 is interposed between the second portion B3 and the beading portion 147 in a folded state at the bottom, and can fix the assembly 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 have a form that is bent together in accordance with the bend shape of the beading portion 147. The insulator 146 can insulate the second portion B3 from the inner surface of the beading portion 147, and at the same time insulate the first current collector 144 from the inner 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 indentation depth D1 of the beading portion 147 is less than or equal to 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 to them, 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 portion of the battery housing 142 in which the electrode assembly 141 is housed and the beading portion 147.

[0555] Since the first part B1 and the third part 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, has been omitted. Therefore, the lead 149 of the first current collector 144 can be directly connected to the lower surface of the cap 143a. With this structure, the empty space within the battery is reduced, and the energy density can be maximized by the amount of the reduced empty space.

[0556] In the cylindrical battery 160, the first current collector 144 and the second current collector 145 can be welded to the ends of the first blank portion 146a and the second blank portion 146b, respectively, as in the embodiment described above.

[0557] The plain sections 146a and 146b are not limited to the illustrated structures. Therefore, the plain sections 146a and 146b may selectively have not only the conventional plain section structure but also the plain section structure of the electrode according to the embodiment (modified version).

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

[0559] Referring to Figure 20, the cylindrical battery 170 differs from the cylindrical battery 140 shown in Figure 17 in that the structure of the electrode assembly is substantially the same, and other structural changes have been made excluding the electrode assembly.

[0560] Specifically, the cylindrical battery 170 includes a battery housing 171 through which terminals 172 are mounted. Terminals 172 are installed through through holes formed in the closed surface (top surface in the drawing) of the battery housing 171. Terminals 172 are riveted into the through holes in the battery housing 171 with a second gasket 173 made of an insulating material interposed between them. Terminals 172 are exposed to the outside in the direction opposite to the direction of gravity.

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

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

[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 part of the first current collector 144 and the upper peripheral 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 opposite polarity, and causing a short circuit.

[0564] The thickness of the insulator 174 corresponds to or is slightly greater than the distance between the upper surface of the first current collector 144 and the inner surface of the closing portion of the battery housing 171. Therefore, the insulator 174 can come into contact with the upper surface of the first current collector 144 and the inner surface of the closing portion of the battery housing 171.

[0565] The terminal insertion portion 172b of the terminal 172 can 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 riveted portion at the bottom of the terminal insertion portion 172b. Preferably, 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, preventing the battery housing 171 and the terminal 172, which have opposite polarities, from making electrical contact. This allows the upper surface of the battery housing 171, which has a substantially flat shape, to function as the second electrode terminal (e.g., the negative electrode) of the cylindrical battery 170.

[0567] The second gasket 173 includes a gasket exposed portion 173a and a gasket inserted portion 173b. The gasket exposed portion 173a is interposed between the terminal exposed portion 172a of the terminal 172 and the battery housing 171. The gasket inserted portion 173b is interposed between the terminal inserted portion 172b of the terminal 172 and the battery housing 171. The gasket inserted portion 173b can be deformed together with the terminal inserted portion 172b during reveting to make it tightly adhere 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 exposed portion 173a of the second gasket 173 may have a shape that extends to cover the outer circumferential surface of the terminal exposed portion 172a of the terminal 172. When the second gasket 173 covers the outer circumferential surface of the terminal 172, it is possible to prevent short circuits from occurring during the process of coupling electrical connection components such as busbars to the upper surface of the battery housing 171 and / or the terminal 172. Although not shown, the gasket exposed portion 173a may have a shape that extends to cover not only the outer circumferential surface of the terminal exposed portion 172a but also a part of the upper surface.

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

[0570] On the upper surface of the battery housing 171, the area 175 other than the area occupied by terminal 172 and the second gasket 173 corresponds to the second electrode terminal having opposite polarity to 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 blank 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 can be fixed by interposing at least a portion of its periphery between the inner surface of the battery housing 171 and the first gasket 178b. For example, at least a portion of the periphery of the second current collector 176 can be fixed to the beading portion 180 formed at the lower end of the battery housing 171 by welding, supported by the lower end surface of the beading portion 180. In a modified example, at least a portion of the periphery of the second current collector 176 can be directly welded to the inner wall surface of the battery housing 171.

[0573] The second current collector 176 may have a plurality of radially formed bumps (not shown) on the surface facing the second blank portion 146b. If bumps are formed, the second current collector 176 can be pressed against the bumps to push the second blank portion 146b into the bumps.

[0574] Preferably, the second current collector 176 and the end of the second plain section 146b can be joined by welding, for example, laser welding. The welded portion between the second current collector 176 and the second plain section 146b can be spaced apart by a predetermined distance toward the core C with respect to the inner circumferential surface of the beading section 180.

[0575] The seal 178 that 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 and the first gasket 178b together. The cap 178a is provided with a vent portion 179. The configuration of the vent portion 179 is substantially the same as that of the above-described embodiment (modification). The lower surface of the cap 178a may be located above 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 so that the crimping portion 181 faces in 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 seal 178 mainly serves to seal the open end at the bottom of the battery housing 171 and to release gas when the internal pressure of the battery 170 increases above a critical value. The critical value of the internal pressure is 15 kgf / cm². 2 ~35 kgf / cm² 2 That is the case.

[0577] Preferably, the terminal 172 electrically connected to the first blank portion 146a of the first electrode is used as the first electrode terminal. In addition, the portion 175 of the upper surface of the battery housing 171, excluding the terminal 172, which is electrically connected to the second blank portion 146b of the second electrode through the second current collector 176, is used as the second electrode terminal with opposite polarity to the first electrode terminal. In this way, when the two electrode terminals are located on the top of the cylindrical battery 170, it is possible to place electrical connection components such as busbars on only one side of the cylindrical battery 170. This can lead to a simplification of the battery pack structure and an improvement in energy density. Furthermore, since the portion 175 used as the second electrode terminal has a substantially flattened shape, it is possible to secure a sufficient connection area for connecting electrical connection components such as busbars. As a result, the cylindrical battery 170 can reduce the resistance at the connection points of electrical connection components to a desirable level.

[0578] On the other hand, the structure of the electrode assembly 141 and the structure of the plain part are not limited to those shown in the figures, and can be replaced with the structures of the above-described embodiments (modified versions).

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

[0580] Referring to Figure 21, the cylindrical battery 180 has substantially the same structure as the cylindrical battery 150 shown in Figure 18 in terms of the electrode assembly 141, and the other components, excluding the electrode assembly 141, are substantially the same as the cylindrical battery 170 shown in Figure 20.

[0581] Therefore, the configurations of the embodiments (modified examples) 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 plain part are not limited to those shown in the figures, and can be replaced with the structures of the above-described embodiments (modified versions).

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

[0584] Referring to Figure 22, the cylindrical battery 190 includes the electrode assembly 110 shown in Figure 14, and the other components, excluding the electrode assembly 110, are substantially identical to those of the cylindrical battery 140 shown in Figure 17. Therefore, the configurations described with reference to Figures 14 and 17 can be applied substantially similarly to this embodiment as well.

[0585] Referring to Figures 10a and 22, the first blank portion 146a and the second blank portion 146b of the electrode assembly 110 are bent radially, for example, from the outer circumference to the core, forming a bent surface region F.

[0586] The first section B1 is shorter in height than the other sections and corresponds to the segment omission section a1 where no segment exists, so it cannot be folded toward the core.

[0587] Preferably, the bent surface region F may include a section a1 where the segment is omitted, a section a2 where the segment height is variable, and a section a3 where the segment height is uniform, from the core side to the outer circumference.

[0588] As shown in Figures 10c, 10d, and 10e, the folded surface region F includes a section a1 where the section is omitted and a section b1 with a uniform number of layers where the number of layers of section is 10 or more, adjacent to the section a1.

[0589] The bent surface region F may also include a layer count reduction section b2 adjacent to the outer circumference of the electrode assembly 110, where the number of layers of segmentation decreases toward the outer circumference. Preferably, a layer count 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 of the height variable section a2 (a2 / c) to the radius region (c) containing the segment, the ratio of the uniform number of layers section b1 (b1 / c) to the radius region (c) containing 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 can be laser-welded to the bent surface region F of the first plain section 146a, and the second current collector 145 can be laser-welded to the bent surface region F of the second plain section 146b. The welding method can be replaced with ultrasonic welding, resistance welding, spot welding, etc.

[0592] Preferably, more than 50% of the welding area W of the first current collector 144 and the second current collector 145 may overlap with the uniform layer number section b1 of the bent surface area F. Optionally, the remaining area of ​​the welding area W may overlap with the decreasing layer number section b2 of the bent surface area F. It is more desirable for the entire welding area W to overlap with the uniform layer number section b1 in terms of high welding strength, low resistance at the welding interface, and prevention of damage to the separation film and active material layer.

[0593] Preferably, in the uniform layer count section b1 overlapping the welding region W, and in the optionally decreasing layer count section b2, the number of layers of the segment may be 10 to 35.

[0594] Selectively, if the number of layers in the segment of the layer-reducing section b2 that overlaps the welding area W is less than 10, the laser output for welding the layer-reducing section b2 may be lower than the laser output for welding the layer-uniform section b1. That is, when the welding area W overlaps simultaneously with the layer-uniform section b1 and the layer-reducing section b2, the laser output can be varied according to the number of layers in the segment. In this case, the welding strength in the layer-uniform section b1 may be greater than the welding strength in the layer-reducing section b2.

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

[0596] In the electrode assembly 110, the height of the first part B1 is relatively lower than that of the other parts. Also, as shown in Figure 14, the bend length H of the plain section located on the innermost side of the third part B2 is smaller than the sum of the radial length R of the first part B1 and 10% of the radius of the core 112.

[0597] Therefore, even if the first blank portion 146a is bent toward the core, more than 90% 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, there is no interference with the electrolyte injection process, and the efficiency of electrolyte injection is improved. In addition, a welding jig can be inserted through the core 112 to facilitate the welding process between the second current collector 145 and the battery housing 142.

[0598] If the plain sections 146a and 146b have a segmented structure, adjusting the width and / or height and / or spacing pitch of the segmented pieces to satisfy the numerical range of the above-described embodiment will ensure that when the segmented pieces are bent, they overlap to a sufficient degree to guarantee sufficient welding strength, and do not form any gaps in the bent surface region 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 segmental sections (see 61, 61' in Figure 10f) that are bent in the last winding turn of the uniform height section a3 of the first and second electrodes. In this case, welding is possible with the segmental sections forming the bent surface region F uniformly pressed by the current collectors, and a tightly stacked state of the segmental sections can be maintained after welding. A tightly stacked state means that there is substantially no gap between the segmental sections, as shown in Figure 10a. A tightly stacked state contributes to reducing the resistance of the cylindrical battery 190 to a level suitable for rapid charging (e.g., 4 mΩ) or below.

[0600] The structure of the plain sections 146a and 146b can be changed to the structure according to the above-described embodiment (modified version). Furthermore, it is not limited that the conventional structure of the plain section may be applied to either one of the plain sections 146a or 146b.

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

[0602] Referring to Figure 23, the cylindrical battery 200 includes the electrode assembly 110 shown in Figure 14, and the other components, excluding the electrode assembly 110, are substantially identical to those of the cylindrical battery 180 shown in Figure 21. Therefore, the configurations described with reference to Figures 14 and 21 can be applied substantially similarly to this embodiment as well.

[0603] Referring to Figures 10a and 23, the first blank portion 146a and the second blank portion 146b of the electrode assembly 110 are bent radially, for example, from the outer circumference to the core, forming a bent surface region F.

[0604] The first section B1 is shorter in height than the other sections and corresponds to the segment omission section a1 where no segment exists, so it cannot be folded toward the core.

[0605] Preferably, the bent surface region F may include a section a1 where the segment is omitted, a section a2 where the segment height is variable, and a section a3 where the segment height is uniform, from the core side to the outer circumference.

[0606] As shown in Figures 10c, 10d, and 10e, the folded surface region F includes a section a1 where the section is omitted and a section b1 with a uniform number of layers where the number of layers of section is 10 or more, adjacent to the section a1.

[0607] The bent surface region F may also include a layer count reduction section b2 adjacent to the outer circumference of the electrode assembly 110, where the number of layers of segmentation decreases toward the outer circumference. Preferably, a layer count 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 of the height variable section a2 (a2 / c) to the radius region (c) containing the segment, the ratio of the uniform number of layers section b1 (b1 / c) to the radius region (c) containing 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 can be laser-welded to the bent surface region F of the first plain section 146a, and the second current collector 176 can be laser-welded to the bent surface region F of the second plain section 146b. The welding method can be replaced with ultrasonic welding, resistance welding, spot welding, etc. The welding region W between the second current collector 176 and the second plain section 146b can be separated from the inner surface of the beading section 180 by a predetermined distance.

[0610] Preferably, more than 50% of the welding area W of the first current collector 144 and the second current collector 176 may overlap with the uniform layer number section b1 of the bent surface area F. Optionally, the remaining area of ​​the welding area W may overlap with the decreasing layer number section b2 of the bent surface area F. It is more desirable for the entire welding area W to overlap with the uniform layer number section b1 in terms of high welding strength, low resistance at the welding interface, and prevention of damage to the separation film and active material layer.

[0611] Preferably, in the uniform layer count section b1 that overlaps with the welding region W, and in the selectively decreasing layer count section b2, the number of layers in the segment can be 10 to 35.

[0612] Selectively, if the number of layers in the segment of the layer-reducing section b2 that overlaps the welding area W is less than 10, the laser output for welding the layer-reducing section b2 may be lower than the laser output for welding the layer-uniform section b1. That is, when the welding area W overlaps simultaneously with the layer-uniform section b1 and the layer-reducing section b2, the laser output can be varied according to the number of layers in the segment. In this case, the welding strength in the layer-uniform section b1 may be even greater than the welding strength in the layer-reducing section b2.

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

[0614] In the electrode assembly 110, the height of the first part B1 is relatively lower than that of the other parts. Also, as shown in Figure 14, the bend length H of the plain section located on the innermost side of the third part B2 is smaller than the sum of the radial length R of the first part B1 and 10% of the radius of the core 112.

[0615] Therefore, even if the first blank portion 146a is bent toward the core, more than 90% 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, there is no interference with the electrolyte injection process, and the efficiency of electrolyte injection is improved. 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 plain section 146a and the second plain section 146b have a segmented structure, if the width and / or height and / or spacing pitch of the segmented pieces are adjusted to satisfy the numerical range of the above-described embodiment, when the segmented pieces are bent, they overlap in sufficient quantities to ensure sufficient welding strength, and do not form any gaps in the bent surface region F.

[0617] Preferably, the first current collector 144 and the second current collector 176 may have an outer diameter that covers the ends of the segmental sections (see 61, 61' in Figure 10f) that are bent in the last winding turn of the uniform height section a3 of the first and second electrodes, in the areas that contact the first blank section 146a and the second blank section 146b. In this case, welding is possible with the segmental sections forming the bent surface region F uniformly pressed by the current collector, and a tightly stacked state of the segmental sections can be maintained after welding. A tightly stacked state means that there is substantially no gap between the segmental sections, as shown in Figure 10a. A tightly stacked state contributes to reducing the resistance of the cylindrical battery 200 to a level suitable for rapid charging (e.g., 4 mΩ) or below.

[0618] The structure of the plain sections 146a and 146b can be changed to the structure according to the above-described embodiment (modified version). Furthermore, it is not limited that the conventional structure of the plain section may be applied to either one of the plain sections 146a or 146b.

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

[0620] Referring to Figure 24, the cylindrical battery 210 includes the electrode assembly 100 shown in Figure 13, and the other components, excluding the electrode assembly 100, are substantially identical to those of the cylindrical battery 140 shown in Figure 17. Therefore, the configurations described with reference to Figures 13 and 17 can be applied substantially similarly to this embodiment.

[0621] Preferably, the first blank portion 146a and the second blank portion 146b of the electrode assembly 100 are divided into a plurality of segments, and the plurality of segments are bent radially of the electrode assembly 100, for example from the outer circumference to the core. In this case, the first portion B1 and the second portion B3 of the first blank portion 146a are shorter in height than the other portions and do not contain segments, so they are not substantially bent. The same applies to the second blank portion 146b.

[0622] In this embodiment as well, the bent surface region F may include a section a1 where the segment is omitted, a section a2 where the height of the segment is variable, and a section a3 where the height of the segment is uniform, from the core side to the outer circumference. However, since the second portion B3 is not bent, the radial length of the bent surface region F may be shorter than in the embodiment described above.

[0623] As shown in Figures 10c, 10d, and 10e, the folded surface region F includes a section a1 where the section is omitted and a section b1 with a uniform number of layers where the number of layers of section is 10 or more, adjacent to the section a1.

[0624] The bent surface region F may also include a layer count reduction section b2 adjacent to the second portion B3 of the electrode assembly 110, where the number of layers of segmentation decreases toward the outer periphery. Preferably, a 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 of the height variable section a2 (a2 / c) to the radius region (c) containing the segmental section, the ratio of the uniform number of layers section b1 (b1 / c) to the radius region (c) containing the segmental section, 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 can be welded to the bent surface region F of the first blank portion 146a, and the second current collector 145 can be welded to the bent surface region F of the second blank portion 146b.

[0627] The overlapping relationship between the uniform layer number section b1 and the decreasing layer number 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 part B1 does not block more than 10% of the core diameter are essentially as described above.

[0628] On the other hand, the second part B3 does not contain any segmentation and is lower in height than the third part B2. Therefore, when the first plain part 146a is folded, the second part B3 is not substantially folded. Also, since the second part B3 is sufficiently separated from the beading part 147, the problem of the second part B3 being damaged during the process of the beading part 147 being pressed in can be solved.

[0629] The structure of the plain sections 146a and 146b can be changed to the structure according to the above-described embodiment (modified version). Furthermore, it is not limited that the conventional structure of the plain section may be applied to either one of the plain sections 146a or 146b.

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

[0631] Referring to Figure 25, the cylindrical battery 220 includes the electrode assembly 100 shown in Figure 24, and the other components, excluding the electrode assembly 100, are substantially the same as those of the cylindrical battery 180 shown in Figure 21. Therefore, the configurations described with reference to Figures 21 and 24 can be applied substantially similarly to this embodiment as well.

[0632] Preferably, the first blank portion 146a and the second blank portion 146b of the electrode assembly 100 are divided into multiple segments and bent from the outer circumference towards the core. In this case, the first portion B1 and the second portion B3 of the first blank portion 146a are lower in height than the other portions and do not contain a segment structure, so they are not substantially bent towards the core. The same applies to the second blank portion 146b.

[0633] Therefore, in this embodiment as well, similar to the embodiment in Figure 24, the bent surface region F may include a section a1 where the segment is omitted, a section a2 where the height of the segment is variable, and a section a3 where the height of the segment is uniform, from the core side to the outer circumference. However, since the second portion B3 is not bent, the radial length of the bent surface region F may be shorter than in the embodiment described above.

[0634] As shown in Figures 10c, 10d, and 10e, the folded surface region F includes a section a1 where the section is omitted and a section b1 with a uniform number of layers where the number of layers of section is 10 or more, adjacent to the section a1.

[0635] The bent surface region F may also include a layer count reduction section b2 adjacent to the second portion B3 of the electrode assembly 110, where the number of layers of segmentation decreases toward the outer periphery. Preferably, a 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 of the height variable section a2 (a2 / c) to the radius region (c) containing the segmental section, the ratio of the uniform number of layers section b1 (b1 / c) to the radius region (c) containing the segmental section, 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 can be welded to the bent surface region F of the first plain section 146a, and the second current collector 176 can be welded to the bent surface region F of the second plain section 146b.

[0638] The overlapping relationship between the uniform layer number section b1 and the decreasing layer number 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 part B1 does not block more than 10% of the core diameter are essentially as described above.

[0639] The structure of the plain sections 146a and 146b can be changed to the structure according to the above-described embodiment (modified version). Furthermore, it is not limited that the conventional structure of the plain section may be applied to either one of the plain sections 146a or 146b.

[0640] In the above-described embodiment (modified version), the first current collector 144 and the second current collector 176 included in the cylindrical batteries 170, 180, 200, and 220, which include 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 vibration resistance and energy density while reducing the resistance of the cylindrical battery. 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 greater than 0.4.

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

[0643] Referring to Figures 23 and 26, the first current collector 144 may include a peripheral portion 144a, a first blank portion connecting portion 144b, and a terminal connecting portion 144c. The peripheral portion 144a is positioned on the upper part of the electrode assembly 110. The peripheral portion 144a has an internal space S inside it. openIt may have a substantially rim shape in which the peripheral portion 144a is formed. The drawings only show the case where the peripheral portion 144a is substantially circular in shape, but this does not limit the present invention. The peripheral portion 144a may be substantially square, hexagonal, octagonal, or any other rim shape, contrary to the figures shown. The number of peripheral portions 144a may be increased to two or more. In this case, another peripheral portion of the rim shape may be included inside the peripheral portion 144a.

[0644] The terminal coupling portion 144c may have a diameter that is the same as or larger than the diameter of the flat portion 172c formed on the bottom surface of the terminal 172, in order to secure a welding area for coupling with the flat portion 172c formed on the bottom surface of the terminal 172.

[0645] The first plain portion joining portion 144b extends inward from the peripheral portion 144a and is joined to the first plain portion 146a by welding. The terminal joining portion 144c is located inside the peripheral portion 144a, separated from the first plain portion joining portion 144b. The terminal joining portion 144c can be joined to the terminal 172 by welding. The terminal joining portion 144c is located in an inner space S surrounded, for example, by the peripheral portion 144a. open It may be located approximately in the center. 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 is not exposed to the outside of the terminal coupling portion 144c. Therefore, the terminal coupling portion 144c may have a larger diameter or width than the hole formed in the core C of the electrode assembly 110.

[0646] The first blank portion connecting portion 144b and the terminal connecting portion 144c are not directly connected but are arranged separately and can be indirectly connected by the peripheral portion 144a. In this way, the first current collector 144 has a structure in which the first blank portion connecting portion 144b and the terminal connecting portion 144c are not directly connected but are connected through the peripheral portion 144a, so that when shock and / or vibration occurs in the cylindrical battery 200, the shock applied to the connection portion between the first blank portion connecting portion 144b and the first blank portion 146a and the connection portion between the terminal connecting portion 144c and the terminal 172 can be dispersed. Four of the first blank portion connecting portions 144b are shown in the drawing, but this does not limit the present invention. The number of the first blank portion connecting portions 144b is determined by 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 Various factors can be taken into consideration when making a decision.

[0647] The first current collector 144 may further include a bridge portion 144d that extends inward from the peripheral portion 144a and is connected to the terminal coupling portion 144c. The bridge portion 144d may be formed with a cross-sectional area smaller than that of the first plain portion coupling portion 144b and the peripheral portion 144a, at least in part. For example, the bridge portion 144d may be formed with a width and / or thickness that is even smaller than that of the first plain portion coupling portion 144b, at least in part. In this case, the electrical resistance of the bridge portion 144d increases, and as current flows through the bridge portion 144d, the relatively large resistance causes melting due to overcurrent heating in part of the bridge portion 144d, which irreversibly interrupts the overcurrent. The cross-sectional area of ​​the bridge portion 144d may be adjusted to an appropriate level to take such overcurrent interruption function into consideration.

[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. When the tapered portion 144e is provided, the rigidity of the component is improved at the connection point between the bridge portion 144d and the peripheral portion 144a. When the tapered portion 144e is provided, in the manufacturing process of the cylindrical battery 200, for example, a transfer device and / or an operator can easily and safely transfer the first current collector 144 and / or the assembly of the first current collector 144 and the electrode assembly 110 by gripping the tapered portion 144e. In other words, when the tapered portion 144e is provided, product defects that occur when gripping parts that are welded to other parts, such as the first plain portion coupling portion 144b and the terminal coupling portion 144c, can be prevented.

[0649] Multiple first plain portion joining portions 144b may be provided. Multiple first plain portion joining portions 144b may be arranged at equal intervals from one another along the extension direction of the peripheral portion 144a. The extended lengths of each of the multiple first plain portion joining portions 144b may be substantially the same. The first plain portion joining portions 144b may be joined to the bent surface region F of the first plain portion 146a by laser welding. Welding may be replaced by ultrasonic welding, spot welding, or the like.

[0650] The weld pattern 144f formed by welding the first plain joint portion 144b and the bent surface region F may have a structure that extends along the radial direction of the electrode assembly 110. The weld pattern 144f may be an arrangement of line patterns or dot patterns.

[0651] The welding pattern 144f corresponds to the welding area. Therefore, it is desirable that the welding pattern 144f overlaps with the uniform layer count section b1 of the bent surface area F by 50% or more. The welding pattern 144f that does not overlap with the uniform layer count section b1 may overlap with the decreasing layer count section b2. More preferably, the entire welding pattern 144f may overlap with the uniform layer count section b1 of the bent surface area F. It is desirable that the uniform layer count section b1 and selectively decreasing layer count section b2 of the bent surface area F below the point where the welding pattern 144f is formed have 10 or more layers per segment.

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

[0653] Although not shown in the figures, there may be multiple bridge portions 144d. Each of the multiple bridge portions 144d may be positioned between adjacent pairs of first plain portion connecting portions 144b. The multiple bridge portions 144d may be positioned at approximately equal intervals from one another along the extension direction of the peripheral portion 144a. The distance from each of the multiple bridge portions 144d to one of adjacent pairs of first plain portion connecting portions 144b along the extension direction of the peripheral portion 144a may be approximately the same as the distance to the other first plain portion connecting portion 144b.

[0654] As described above, when multiple first blank section connecting portions 144b and / or bridge portions 144d are provided, if the distance between the first blank section connecting portions 144b and / or the distance between the bridge portions 144d and / or the distance between the first blank section connecting portions 144b and bridge portions 144d is kept constant, then a smooth flow of current from the first blank section connecting portions 144b to the bridge portions 144d or from the bridge portions 144d to the first blank section connecting portions 144b will be formed.

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

[0656] The notched portion N is preferably provided in a region corresponding to the uniform layering section of the electrode assembly 110 in order to prevent foreign matter generated during fracture from flowing into the inside of the electrode assembly 110. This is because in this region the number of layers of the segment of the first blank portion 146a is maintained at its maximum, and the overlapping segment can function as a mask.

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

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

[0659] Referring to Figures 23 and 27, the second current collector 176 is positioned at the bottom of the electrode assembly 110. The second current collector 176 may also be configured to electrically connect the plain 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 plain 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 interposing its periphery between the inner surface of the battery housing 171 and the first gasket 178b. Specifically, the periphery of the second current collector 176 may be 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 alternatively, 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 positioned at the bottom of the electrode assembly 110, a second plain portion connecting portion 176b extending substantially radially from the support portion 176a and coupled to the bent surface region F of the plain portion 146b, and a housing connecting portion 176c extending inclined toward the inner surface of the battery housing 171 with respect to the radial direction of the electrode assembly 110 and coupled to the inner surface. The second plain portion connecting portion 176b and the housing connecting portion 176c are indirectly connected through the support portion 176a and are not directly connected to each other. Therefore, when an external impact is applied to the cylindrical battery 200 of the present invention, damage to the coupling portion between the second current collector 176 and the electrode assembly 110 and the coupling portion 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 blank portion coupling portion 176b and the housing coupling portion 176c are indirectly connected. For example, the second current collector 176 may have a structure in which there is no support portion 176a that indirectly connects the second blank portion coupling portion 176b and the housing coupling portion 176c, and / or a structure in which the blank portion 146b and the housing coupling portion 176c are directly connected.

[0661] The support portion 176a and the second plain portion connecting portion 176b are located at the bottom of the electrode assembly 110. The second plain portion connecting portion 176b is connected to the bent surface region F of the plain portion 146b. Not only the second plain portion connecting portion 176b, but the support portion 176a can also be connected to the plain portion 146b. The second plain portion connecting portion 176b and the bent surface region F of the plain portion 146b can be connected by laser welding. Welding can be replaced by ultrasonic welding, spot welding, etc. The support portion 176a and the second plain portion connecting portion 176b are located above the beading portion 180 if the beading portion 180 is formed on the battery housing 171.

[0662] The support portion 176a includes a current collector 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 collector hole 176d, which are in communication with each other, can function as a passage for inserting a welding rod for welding between the terminal 172 and the terminal coupling portion 144c of the first current collector 144, or for irradiating with a laser beam.

[0663] The current collector hole 176d is a hole formed in the core C of the electrode assembly 110 with radius r c 0.5r c It may have a radius greater than or equal to the above. The radius of the current collector plate hole 176d is 0.5r c ~1.0r c In this case, when venting occurs in the cylindrical battery 200, the venting pressure prevents the separation membrane and electrode winding structure near the core C of the electrode assembly 110 from being pushed outwards from the core C. The radius of the current collector hole 176d is 1.0r c If the value is larger than this, the core C is opened to its maximum extent, making it easier to inject the electrolyte during the electrolyte injection process.

[0664] When a plurality of the second blank portion connecting portions 176b are provided, the plurality of second blank portion connecting portions 176b may have a configuration in which they extend substantially radially from the support portion 176a of the second current collector 176 toward the side wall of the battery housing 171. Each of the plurality of second blank portion connecting portions 176b may be located spaced apart from each other along the perimeter of the support portion 176a.

[0665] Multiple housing coupling portions 176c may be provided. In this case, the multiple housing coupling portions 176c may have a configuration that extends substantially radially from the center of the second current collector 176 toward the side wall of the battery housing 171. This allows for electrical connection between the second current collector 176 and the battery housing 171 at multiple points. By performing coupling for electrical connection at multiple points in this way, the coupling area can be maximized and electrical resistance can be minimized. Each of the multiple housing coupling portions 176c may be located spaced apart from each other along the perimeter of the support portion 176a. At least one housing coupling portion 176c may be located between adjacent second plain portion coupling portions 176b. The multiple housing coupling portions 176c may be coupled to the inner surface of the battery housing 171, for example, the beading portion 180. The housing coupling portions 176c may be coupled to the lower surface of the beading portion 180 in particular by laser welding. Welding can be replaced by ultrasonic welding, spot welding, etc. By welding multiple housing coupling portions 176c onto the beading portion 180 in this manner, the current path can be distributed radially, limiting the resistance level of the cylindrical battery 200 to approximately 4 mΩ or less. Furthermore, by shaping the lower surface of the beading portion 180 to extend in a direction substantially parallel to the upper surface of the battery housing 171, that is, in a direction substantially perpendicular to the side wall of the battery housing 171, and shaping the housing coupling portions 176c to extend in the same direction, that is, 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 portion of the beading portion 180 in this manner, welding between the two parts is performed smoothly, thereby improving the bonding force between the two parts and minimizing the increase in resistance at the joint.

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

[0667] The contact portion 176e is coupled to the 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 have a form that extends for a predetermined length along the circumferential direction of the battery housing 171 in the beading portion 180.

[0668] The connecting portion 176f can be bent at an obtuse angle. The bending point may be above 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 is divided into a lower and upper part with respect to the bending point, and the length of the lower part may be greater than that of the upper part. Also, the inclination angle with respect to the surface of the support portion 176a may be even greater at the lower part of the bending point than at the upper part. When the connecting portion 176f is bent, it can buffer the 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 connecting portion 176f is deformed as the bending point of the connecting portion 176f moves upward, thereby buffering stress.

[0669] On the other hand, it is desirable that the maximum distance from the center of the second current collector 176 to the end of the second plain section connecting portion 176b along the radial direction of the electrode assembly 110 be the same as 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 plain section connecting portion 176b from pressing against the end of the electrode assembly 110 during the sizing process in which the battery housing 171 is compressed along the height direction.

[0670] The second plain joint 176b includes a hole 176g. The hole 176g can be used as a passage for the electrolyte to move. The weld pattern 176h formed by welding the second plain joint 176b to the bent surface region F may have a structure that extends along the radial direction of the electrode assembly 110. The weld pattern 176h may be an arrangement of line patterns or dot patterns.

[0671] The welding pattern 176h corresponds to the welding area. Therefore, it is desirable that the welding pattern 176h overlaps by 50% or more with the uniform layer count section b1 of the bent surface region F located below the electrode assembly 110. The welding pattern 176h that does not overlap with the uniform layer count section b1 may overlap with the decreasing layer count section b2. More preferably, the entire welding pattern 176h may overlap with the uniform layer count section b1 of the bent surface region F. It is desirable that the uniform layer count section b1 and selectively decreasing layer count section b2 of the bent surface region F located above the point where the welding pattern 176h is formed have 10 or more layers per segment.

[0672] The first current collector 144 and the second current collector 176 described above have different outer diameters. The outer diameter is the outer diameter of the outer edge of the contact area between the bent surface region F and the current collector. The outer diameter is defined as the maximum value of the distance between two points where a straight line passing through the center of the electrode assembly core C intersects with the edge of the contact area. Since the second current collector 176 is located inside the beading portion 180, its outer diameter is smaller than that of the first current collector 144. Also, the length of the welding pattern 144f of the first current collector 144 is even longer than the length of the welding pattern 176h of the second current collector 176. Preferably, the welding patterns 144f and 176h can be extended outward from substantially the same point with respect to the center of the core C.

[0673] The cylindrical batteries 170, 180, 200, and 220 according to embodiments of the present invention can be electrically connected at the top.

[0674] Figure 28 is a top view showing multiple cylindrical batteries 200 electrically connected, and Figure 29 is a partial enlargement of Figure 28. The cylindrical battery 200 can be replaced with cylindrical batteries 170, 180, and 220 of other structures.

[0675] Referring to Figures 28 and 29, multiple cylindrical batteries 200 can be connected in series and parallel at the top of the cylindrical batteries 200 using busbars 210. The number of cylindrical batteries 200 can be increased or decreased depending on the capacity of the battery pack.

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

[0677] Preferably, multiple cylindrical batteries 200 may be arranged in multiple columns and rows. In the drawing, columns are provided in the vertical direction and rows in the horizontal direction. Also, to maximize space efficiency, the cylindrical batteries 200 may be arranged in a closest packing structure. A closest packing structure is formed when the centers of the terminals 172 exposed to the outside of the battery housing 171 are connected to form an equilateral triangle. Preferably, the busbar 210 connects cylindrical batteries 200 arranged in the same column in parallel and connects cylindrical batteries 200 arranged in two adjacent columns in series.

[0678] Preferably, the busbar 210 may include a body 211, a plurality of first busbar terminals 212, and a plurality of second busbar terminals 213 for series and parallel connections.

[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 be regularly bent in a zigzag pattern.

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

[0681] Multiple second busbar terminals 213 can extend from the other side of the body portion 211 and be electrically connected to the flattened surface 171a around terminal 172 located on the other side. The electrical coupling between the second busbar terminals 213 and the flattened surface 171a can be performed by laser welding, ultrasonic welding, or the like.

[0682] Preferably, the body portion 211, the plurality of first busbar terminals 212, and the plurality of second busbar terminals 213 may be made of 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. As a modification, the body portion 211, the plurality of first busbar terminals 212, and the second busbar 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 increasing the welding area through the bent surface region F, doubling the current path using the second current collector 176, and minimizing the current path length. The AC resistance of the cylindrical battery 200, measured by a resistance meter between the positive electrode and the negative electrode, i.e., between the terminal 172 and the surrounding flattened surface 171a, can be 0.5 mΩ to 4 mΩ, preferably 1 mΩ to 4 mΩ, which is suitable for rapid charging.

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

[0685] Furthermore, because the terminals 172 of the cylindrical battery 200 and the surrounding flat surface 171a have a large surface area, sufficient bonding area for the busbar 210 can be secured, and the resistance of the battery pack including the cylindrical battery 200 can be sufficiently reduced.

[0686] Furthermore, 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 (modified version) is used in the manufacture of a battery pack.

[0688] Figure 30 is a schematic diagram showing the configuration of a battery pack according to one embodiment of the present invention.

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

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

[0691] Figure 31 is a diagram illustrating an automobile including the battery pack 300 shown in Figure 30.

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

[0693] According to the present invention, by using the plain parts protruding from the upper and lower parts of the electrode assembly as electrode tabs, the internal resistance of the battery can be reduced and the energy density can be increased.

[0694] According to another embodiment of the present invention, by improving the structure of the plain portion of the electrode assembly so that the electrode assembly and the inner circumferential surface of the battery housing do not interfere with each other during the beading portion formation process of the battery housing, it is possible to prevent internal short circuits in the cylindrical battery due to partial deformation of the electrode assembly.

[0695] According to yet another embodiment of the present invention, the structure of the plain portion of the electrode assembly can be improved to prevent the plain portion from tearing when bent, and the number of overlapping layers of the plain portion can be sufficiently increased to improve the welding strength of the current collector.

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

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

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

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

[0700] According to yet another embodiment of the present invention, it is possible to provide a cylindrical battery having a structure with low internal resistance, prevention of internal short circuits, and improved welding strength between the current collector and the blank portion, a battery pack including the same, and an automobile.

[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 an automobile.

[0702] As described above, the present invention has been explained with limited embodiments and drawings, but it goes without saying that the present invention is not limited thereto, and that various modifications and variations are possible within the equivalent scope of the technical concept and claims of the present invention by persons with ordinary skill in the art to which the present invention pertains.

Claims

1. An electrode assembly in which a core and an outer surface are defined by winding a first electrode, a second electrode, and a separation membrane interposed between them around a winding shaft, The first electrode includes a first active material portion coated with an active material layer along the winding direction, and a first plain portion not coated with an active material layer. At least a portion of the first blank portion is defined as an electrode tab, The first blank portion includes a first portion adjacent to the core of the electrode assembly, a second portion adjacent to the outer peripheral surface of the electrode assembly, and a third portion between the first portion and the second portion. The heights of the first part, the second part, and the third part are greater than 0. The first or second portion has a lower height than the third portion in the winding axis direction, The third portion is bent along the radial direction of the electrode assembly to define a bent surface region, The first or second portion has a height lower than the bent surface region, In the aforementioned bent surface region, the third portion forms a welding target region which is stacked as multiple superimposed layers along the winding axis direction. The welding target region includes an electrode assembly in which the number of superimposed layers intersecting a virtual line parallel to the winding axis direction is 10 or more.

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

3. The electrode assembly according to claim 2, wherein each of the multiple segments has the form of a geometric figure formed by connecting one or more straight lines, one or more curves, or a combination thereof.

4. Each of the multiple sections is, Is the width of the bottom wider than the width of the top? Is the width of the bottom equal to the width of the top? Does the width decrease from the bottom to the top? Does the width decrease from the bottom to the top and then increase again? Does the width increase from the bottom to the top and then decrease, The width increases from the bottom to the top and then remains constant, or, The electrode assembly according to claim 3, wherein the width decreases from the bottom to the top and then remains constant.

5. The electrode assembly according to claim 3, wherein the multiple segments increase individually, in groups, or in units of multiple groups, toward one direction parallel to the winding direction at the lower interior angle.

6. The electrode assembly according to claim 5, wherein the multiple segments are individually, group by group, or in units of multiple groups, with the lower inner angle increasing in a range of 60° to 85° in one direction parallel to the winding direction.

7. Each of the aforementioned subsections has a geometric shape in which the width decreases from the bottom to the top, and the lower interior angle θ of a subsection located in a winding turn with radius r centered on the core of the electrode assembly falls within the angle range of the following formula: [Math 1] The electrode assembly according to claim 2, wherein D is the width of the segment in the winding direction, r is the radius of the winding turn containing the segment, H is the height of the segment, and p is the spacing pitch of the segment.

8. Each of the multiple sections is, The sides consist of straight lines, curves, or a combination thereof. The sides are convex outwards or convex inwards, or The electrode assembly according to claim 3, wherein the upper corners have a rounded shape.

9. The electrode assembly according to claim 3, wherein the geometric shapes of the multiple segments change individually, in groups, or in groups of two or more groups along one direction parallel to the winding direction.

10. The electrode assembly according to claim 2, wherein cutting grooves are interposed between adjacent segmental sections along the winding direction, and the lower part of the cutting grooves includes a bottom portion and rounded portions that connect both ends of the bottom portion with the side edges of the segmental sections on both sides of the cutting grooves.

11. The electrode assembly according to claim 10, wherein the plurality of subsections have a separation pitch defined by the distance between two points where lines extending from the side edges of two subsections located on both sides of the cutting groove intersect with a line extending from the bottom of the cutting groove, and the separation pitch changes along one direction parallel to the winding direction.

12. The electrode assembly according to claim 11, wherein the separation pitch of the plurality of segments varies on a group basis or on a group basis of two or more groups.

13. The electrode assembly according to claim 10, wherein the bottom of the cutting groove is separated from the active material layer by a certain distance.

14. The electrode assembly according to claim 13, wherein the separation distance between the bottom of the cutting groove and the active material layer changes along one direction parallel to the winding direction.

15. The electrode assembly according to claim 14, wherein the separation distance between the bottom of the cutting groove and the active material layer varies individually, in groups, or in groups of two or more along one direction parallel to the winding direction.

16. The electrode assembly according to claim 10, wherein the plurality of subsections are bent radially in a 0-1 mm section above the bottom of the cutting groove.

17. When the radius of the winding turn containing the segment is defined as r, relative to the core center of the electrode assembly, and the width of the segment in the winding direction is defined as D(r), then D(r) is given by the following formula 1≦D(r)≦(2×π×r / 360°)×45° The electrode assembly according to claim 2, satisfying the requirements.

18. The electrode assembly according to claim 17, wherein each of the plurality of subsections has a winding width D(r) that gradually or stepwise increases or decreases as the radius r of the winding turn in which the subsection is located increases with respect to the core center of the electrode assembly.

19. The electrode assembly according to claim 17, wherein each of the plurality of subsections has a winding width D(r) that gradually or stepwise increases and then gradually or stepwise decreases, or vice versa, as the radius r of the winding turn in which the subsection is located increases with respect to the core center of the electrode assembly.

20. The electrode assembly according to claim 17, wherein each of the plurality of segments has substantially the same inscribed angle with respect to the core center of the electrode assembly.

21. The electrode assembly according to claim 17, wherein the plurality of segments increase in width in the winding direction by substantially the same ratio along one direction parallel to the winding direction of the electrode assembly.

22. The electrode assembly according to claim 2, wherein each of the plurality of subsections has a winding width that gradually or stepwise increases within the range of 1 mm to 11 mm as the radius r of the winding turn in which the subsection is located increases with respect to the core center of the electrode assembly.

23. The electrode assembly according to claim 1, wherein at least a portion of the third portion has a height in the winding axis direction that changes gradually or in steps in one direction parallel to the winding direction.

24. The electrode assembly according to claim 23, wherein at least a portion of the second and third portions has a height in the winding axis direction that gradually or in steps increases in one direction parallel to the winding direction.

25. The electrode assembly according to claim 23, wherein the third portion is divided into a plurality of regions of different heights along one direction parallel to the winding direction, and the height of the first plain portion in the plurality of regions increases in steps along one direction parallel to the winding direction.

26. The first plain section has a first height h along one direction parallel to the winding direction. １ ~N-1 height h Ｎ－１ A variable height interval that increases stepwise up to (where N is the height index and is a natural number greater than or equal to 3), and a height h of N. Ｎ (h Ｎ－１ The electrode assembly according to claim 2, comprising a height uniform section that is uniformly maintained at a greater than (or greater) level.

27. The electrode assembly according to claim 26, wherein N is 2 to 30.

28. The aforementioned height h ｋ The number of segmental intercepts (where k is a natural number from 1 to N) is multiple, and the height h ｋ The electrode assembly according to claim 26, wherein the plurality of segments having are arranged in one or more winding turns.

29. Height h ｋ Let r be the starting radius of the winding turn including the segment slice having (k is a natural number from 1 to N). ｋ Let r be the radius of the core ｃ When this is the case, the height h of the segment slice ｋ is given by the following formula 2 mm ≤ h ｋ ≤r ｋ -α × r ｃ (α is between 0.90 and 1) The electrode assembly according to claim 26, satisfying the requirements.

30. The electrode assembly according to claim 2, wherein the electrode assembly includes, sequentially along the radial direction with respect to a cross section along the winding axis direction, a section without a section, a height-variable section where the height of the section changes, and a height-uniform section where the height of the section is uniform, and the plurality of section pieces 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.

31. The electrode assembly according to claim 30, wherein the first portion is not divided into segments, and the segment-omitted section corresponds to the first portion.

32. The electrode assembly according to claim 30, wherein the third portion is divided into a plurality of independently foldable segments, and the height-variable section and the height-uniform section correspond to the third portion.

33. The electrode assembly according to claim 30, wherein the second and third parts are divided into a plurality of independently foldable segments, and the height-variable section and the height-uniform section correspond to the second and third parts.

34. The electrode assembly according to claim 30, wherein the height of the segment arranged in the height-variable section is gradually or stepwise increased within the range of 2 mm to 10 mm.

35. The aforementioned multiple sections are, At least one of the width in the winding direction and the height in the winding direction is increased stepwise or continuously in one direction parallel to the winding direction, or The electrode assembly according to claim 2, wherein at least one selected from the width in the winding direction and the height in the winding direction direction increases gradually or continuously and then decreases gradually or continuously in one direction parallel to the winding direction, or vice versa.

36. The plurality of segments form a plurality of segment groups along one direction parallel to the winding direction of the electrode assembly. Sections belonging to the same section group are: Are the width in the winding direction and the height in the winding direction substantially the same? At least one of the width in the winding direction and the height in the winding direction of the electrode assembly increases gradually or in steps, or, The electrode assembly according to claim 2, wherein the lower interior angle gradually or stepwise increases in one direction parallel to the winding direction of the electrode assembly, either in groups or in groups of two or more.

37. The electrode assembly according to claim 36, wherein when the widths in the winding direction for each of three continuously adjacent segment groups in one direction parallel to the winding direction of the electrode assembly are W1, W2, and W3, respectively, the combination of segment groups includes one in which W3 / W2 is smaller than W2 / W1.

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

39. The electrode assembly according to claim 1, wherein the second portion is not divided into segments, and the second portion is not bent along the radial direction of the electrode assembly.

40. The electrode assembly according to claim 10, wherein an insulating coating layer is formed at the boundary between the plain area in the section where the bottom of the cutting groove and the active material layer are separated, and the active material layer.

41. The end of the insulating coating layer is located in a range of -2 mm to 2 mm along the winding axis direction with respect to the end of the separation film. The insulating coating layer is exposed to the outside of the separation film, The lower end of the cutting groove and the insulating coating layer are separated by a distance of 0.5 mm to 2 mm, or The electrode assembly according to claim 40, wherein the end of the insulating coating layer in the winding axis direction is located within a range of -2 mm to +2 mm with respect to the lower end of the cutting groove.

42. The electrode assembly according to claim 40, wherein the separation distance between the lower end of the cutting groove and the insulating coating layer of the plurality of segments varies along one direction parallel to the winding direction.

43. The electrode assembly according to claim 1, wherein the third and second portions are divided into a plurality of independently bendable segments, and the plurality of segments define the bendable surface region as they are bent along the radial direction of the electrode assembly.

44. The electrode assembly according to claim 43, wherein, with respect to the core center of the electrode assembly, the number of segmental segments that intersect a virtual line parallel to the winding axis direction at any radial position in the bent surface region is defined as the number of stacked segmental segments at the corresponding radial position, and the bent surface region includes a uniform stacking section in which the number of stacked segmental segments is uniform from the core side toward the outer circumference, and a decreasing stacking section located outside the uniform stacking section in which the number of stacked segmental segments decreases toward the outer circumference.

45. The electrode assembly according to claim 44, wherein the radial lengths of the uniform number of layers section and the decreasing number of layers section correspond to the radial lengths of the radial sections in which the winding turns containing the plurality of subsections are located, with respect to the core center of the electrode assembly.

46. The electrode assembly according to claim 44, wherein the electrode assembly sequentially includes a section without a segment, a height-variable section where the height of the segment changes, and a height-uniform section where the height of the segment is uniform, along the radial direction, and the radius at which the uniform stacking section begins with respect to the core center of the electrode assembly corresponds to the radius at which the height-variable section begins.

47. The electrode assembly according to claim 44, wherein the number of layers of the segment in the uniform layering interval is 10 to 35.

48. The electrode assembly according to claim 44, wherein the first electrode is a positive electrode, and the stacking thickness of the segment in the uniform stacking section is 100 μm to 875 μm.

49. The electrode assembly according to claim 44, wherein the first electrode is a negative electrode, and the stacking thickness of the segment in the uniform stacking section is 50 μm to 700 μm.

50. The electrode assembly according to claim 44, wherein the ratio of the radial length of the uniform number of layers section to the radial length of the uniform number of layers section and the decreasing number of layers section is 30% to 85%.

51. The electrode assembly according to claim 44, further comprising a current collector welded to the bent surface region, wherein in the radial direction of the electrode assembly, the welded region of the current collector overlaps the uniform layering section by at least 50%.

52. The electrode assembly according to claim 51, wherein in the radial direction of the electrode assembly, the region of the welding area of ​​the current collector that does not overlap with the uniform layer number section overlaps with the decreasing layer number section.

53. The electrode assembly according to claim 51, wherein the periphery of the current collector is welded to the bent surface region in such a manner that it is positioned on the bent surface region to cover the end of the bent portion of the outermost segment of the electrode assembly in the radial direction.

54. The welding strength of the current collector in the welding area is 2 kgf / cm ２ The electrode assembly according to claim 51, wherein the pressure is 0.2 MPa or greater.

55. The electrode assembly according to claim 1, wherein the height of the second portion decreases in stages or gradually from the core side to the outer circumference side of the electrode assembly.

56. The electrode assembly according to claim 1, wherein the second and third parts are divided into a plurality of independently foldable segments, and the segments included in the second part have at least one greater width in the winding direction and height in the winding direction than the segments included in the third part.

57. The electrode assembly according to claim 2, wherein the third portion includes a segment-omitted section in which no segment segments exist along the winding direction of the electrode assembly.

58. The electrode assembly according to claim 57, wherein the third portion includes a plurality of segment omission sections along one direction parallel to the winding direction.

59. The electrode assembly according to claim 58, wherein the width of each of the plurality of segment omission sections increases or decreases along one direction parallel to the winding direction.

60. The electrode assembly according to claim 57, wherein the height of the blank portion of the section omitted is substantially the same as the height of the blank portion of the first portion or the blank portion of the second portion.

61. The electrode assembly according to claim 57, wherein the plurality of segments are located within a predetermined circular angle range with respect to the core center of the electrode assembly.

62. The electrode assembly according to claim 57, wherein the plurality of segments are located in two or more sector-shaped or polygonal regions arranged circumferentially with respect to the core center of the electrode assembly.

63. The electrode assembly according to claim 62, wherein the inscribed angle of the sector-shaped region is 20° or more.

64. An electrode assembly according to any one of claims 1 to 63, A battery housing having an open end and a bottom opposite to it, housing the electrode assembly in the space between the open end and the bottom, and electrically connected to one of the first electrode and the second electrode to have a first polarity, A sealing body that seals the open end of the battery housing, A battery comprising a terminal electrically connected to the other of the first electrode and the second electrode, with its surface exposed to the outside and having a second polarity.

65. The battery according to claim 64, wherein the second portion has a lower height in the winding axis direction than the third portion, the battery housing includes a beading portion pushed inward in a region 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 separated by a predetermined distance.

66. The battery according to claim 65, 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 relation D1 ≤ D2.

67. A current collector electrically connected to the third part, The battery according to claim 65, further comprising an insulator that covers the current collector and whose periphery is interposed and fixed between the inner surface of the beading portion and the current collector.

68. The battery according to claim 67, wherein 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 is the same as or larger than the outermost diameter of the third portion.

69. The battery according to claim 67, wherein the current collector is positioned higher than the beading portion in the winding axis direction.

70. The battery according to claim 64, 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 inward into 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.

71. The battery according to claim 64, further comprising a first current collector electrically connected to the first blank portion, wherein the terminal is a rivet terminal having the second polarity, insulatedly mounted in a through hole formed in the bottom of the battery housing and electrically connected to the first current collector.

72. The battery according to claim 71, 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.

73. The battery according to claim 72, wherein 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 is in close contact with the inner surface of the bottom of the battery housing and the upper surface of the first current collector.

74. The battery according to claim 72, wherein the terminal includes a flat portion at its lower end, the insulator includes an opening that exposes the flat portion, and the flat portion is welded to the first current collector through the opening.

75. The battery according to claim 64, wherein the second electrode includes a second active material portion coated with an active material layer along the winding direction and a second blank portion not coated with an active material layer, the second electrode has the first polarity, and at least a portion of the second blank portion is defined by itself as an electrode tab, and further includes a second current collector electrically connected to the second blank portion and having at least a portion of its periphery coupled to the side wall of the battery housing.

76. The battery according to claim 71, wherein the second electrode includes a second active material portion coated with an active material layer along the winding direction and a second blank portion not coated with an active material layer, the second electrode has the first polarity, and at least a portion of the second blank portion is defined by itself as an electrode tab, further including a second current collector electrically connected to the second blank portion and having at least a portion of its periphery bonded to the side wall of the battery housing, the outer diameter of the first current collector being the same as or larger than the outer diameter of the second current collector.

77. The battery according to claim 76, wherein the first current collector and the second current collector are welded to the first blank portion and the second blank portion of the electrode assembly along the radial direction to form a weld pattern, and the length of the weld pattern of the first current collector is even longer than the length of the weld pattern of the second current collector.

78. The battery according to claim 77, wherein the welding pattern of the first current collector and the welding pattern of the second current collector are located at substantially the same distance from the core center of the electrode assembly.

79. The battery according to claim 75, wherein the battery housing includes a beading portion pressed inward against the inner wall adjacent to the open end, and the periphery of the second current collector is electrically connected to the beading portion.

80. The battery according to claim 79, wherein the region in which the second current collector electrically contacts the second blank portion is located inward from the inner circumferential surface of the beading portion.

81. The battery according to claim 79, comprising: a cap whose periphery is supported by the beading portion; a gasket interposed between the periphery of the cap and the open end of the battery housing; and a crimping portion that extends inward from 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.

82. The battery according to claim 79, wherein the periphery of the second current collector is welded to the beading portion.

83. A battery pack comprising a plurality of batteries according to any one of claims 64 to 82.

84. The battery pack according to claim 83, wherein the battery has a height-to-diameter ratio greater than 0.

4.

85. The battery pack according to claim 84, wherein the form factor of the battery is 46110, 4875, 48110, 4880, or 4680.

86. The battery pack according to claim 83, wherein the resistance of the battery is 4 mΩ or less.

87. The battery pack according to claim 83, wherein multiple 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 positioned facing upward.

88. A battery pack according to claim 87, comprising a plurality of busbars connecting a plurality of batteries in series and parallel, wherein the plurality of busbars are positioned on top of the plurality of batteries, and each of the plurality of busbars includes a body portion extending between the terminals of adjacent batteries, a plurality of first busbar terminals extending to one side of the body portion and electrically coupled to the terminals of the battery located on that side, and a plurality of second busbar terminals extending to the other side of the body portion and electrically coupled to the outer surface of the bottom of the battery housing of the battery located on the other side.

89. An automobile comprising a battery pack according to any one of claims 83 to 88.

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