Electrode assembly, battery, battery pack including the same, and motor vehicle

Abstract

The present invention discloses an electrode assembly, a battery, a battery pack including the same, and an automobile, in which an end surface of the electrode assembly includes a plurality of segment alignment portions in which a plurality of segment groups are aligned along a radial direction, and an electrolyte impregnation portion in which an end of an active material portion is exposed between adjacent segment alignment portions in a circumferential direction from a space between the wound turns of a separator, the segment included in the segment alignment portion forms a folded surface region, and the end of the separator is spaced apart by 30% or less of the minimum height of the segment forming the folded surface region from a reference line extending in the winding axis direction along a position corresponding to the cut groove between the segment.

Description

Technical Field

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

[0002] This application claims priority based on Korean Patent Application No. 10-2021-0160823 filed on November 19, 2021 and Korean Patent Application No. 10-2022-0005393 filed on January 13, 2022, and all of the content disclosed in the specifications and drawings of the applications is incorporated herein.

Background Art

[0003] Secondary batteries with high applicability for each product group and having electrical characteristics such as high energy density are generally applied not only to portable devices but also to electric vehicles (EVs) or hybrid electric vehicles (HEVs) driven by an electric drive source.

[0004] Such secondary batteries are attracting attention as a new energy source for improving energy efficiency because they have not only the primary advantage of significantly reducing the use of fossil fuels but also the point of being environmentally friendly in that no by-products are generated by the use of energy.

[0005] Currently, secondary batteries such as lithium-ion batteries, lithium polymer batteries, nickel cadmium batteries, nickel metal hydride batteries, and nickel zinc batteries are widely used. The operating voltage of such a unit secondary battery, that is, a unit battery, is about 2.5V to 4.5V. Therefore, when a higher output voltage is required, a plurality of batteries are connected in series to form a battery pack. Also, depending on the charge and discharge capacity required for the battery pack, a plurality of batteries may be connected in parallel to form a battery pack. Therefore, the number and electrical connection form of the batteries included in the battery pack can be variously set according to the required output voltage and / or charge and discharge capacity.

[0006] On the one hand, as types of unit secondary batteries, cylindrical, prismatic, and pouch-type batteries are known. In the case of a cylindrical battery, a separator, which is an insulator, is interposed between the positive electrode and the negative electrode, and this is wound up to form a jelly-roll type electrode assembly, which is inserted inside a battery housing to constitute the battery. The battery housing is called a battery can in the industry. And, strip-shaped electrode tabs are connected to the plain portions of the positive electrode and the negative electrode respectively, and the electrode tabs electrically connect between the electrode assembly and the electrode terminals exposed 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, according to the conventional cylindrical battery having such a structure, since current is concentrated on the strip-shaped electrode tab coupled to the positive electrode plain portion and / or the negative electrode plain portion, there is a problem that the resistance is large, heat generation is much, and the current collection efficiency is not good.

[0007] In the case of small cylindrical batteries having a form factor of 1865 (diameter: 18 mm, height: 65 mm) or 2170 (diameter: 21 mm, height: 70 mm), resistance and heat generation are not much of a problem. However, when increasing the form factor for applying the cylindrical battery to an electric vehicle, there may occur a problem that the cylindrical battery catches fire while a large amount of heat is generated around the electrode tab during the rapid charging process.

[0008] To solve such a problem, a cylindrical battery (so-called tab-less cylindrical battery) having a structure in which the positive electrode plain portion and the negative electrode plain portion are respectively located at the upper end and the lower end of the jelly-roll type electrode assembly, and a current collector is welded to such a plain portion to improve the current collection efficiency has been proposed.

[0009] FIGS. 1 to 3 are diagrams showing the manufacturing process of the tab-less cylindrical battery. FIG. 1 shows the structure of the electrode, FIG. 2 shows the winding process of the electrode, and FIG. 3 shows the process in which the current collector is welded to the bent surface region of the plain portion.

[0010] Referring to FIGS. 1 to 3, the positive electrode 10 and the negative electrode 11 have a structure in which the active material 21 is coated on the sheet-like current collector 20, and include a non-patterned portion 22 on one long side along the winding direction (X-axis). The long side is a direction parallel to the X-axis direction and means the side with a relatively long length.

[0011] The electrode assembly A is manufactured by laminating the positive electrode 10 and the negative electrode 11 in order together with two separator membranes 12 as shown in FIG. 2, and then winding them in one direction (X-axis direction). At this time, the non-patterned portion of the positive electrode 10 and the non-patterned portion of the negative electrode 11 are arranged in opposite directions.

[0012] After the winding process, the non-patterned portion 10a of the positive electrode 10 and the non-patterned portion 11a of the negative electrode 11 are bent toward the core side. Then, the current collectors 30 and 31 are welded and joined to the non-patterned portions 10a and 11a, respectively.

[0013] No separate electrode tabs are connected to the positive electrode non-patterned portion 10a and the negative electrode non-patterned portion 11a. The current collectors 30 and 31 are connected to external electrode terminals, and the current path is formed with a large cross-sectional area along the winding axis direction (see arrow) of the electrode assembly A. Therefore, there is an advantage that the resistance of the battery can be reduced. This is because the resistance is inversely proportional to the cross-sectional area of the path through which the current flows.

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

[0015] However, when bending the welding regions of the plain portions 10a and 11a, the patterns on the plain portions 10a and 11a may be deformed while being irregularly distorted. In this case, the deformed portion may come into contact with an electrode of the opposite polarity and cause an internal short circuit, or may induce fine cracks in the plain portions 10a and 11a. Further, while the plain portion 32 adjacent to the core of the electrode assembly A is being bent, all or a substantial part of the cavity 33 in the core of the electrode assembly A is blocked. In this case, problems occur in the electrolyte injection process. That is, the cavity 33 in the core of the electrode assembly A is used as a passage through which the electrolyte is injected. However, if the passage is blocked, it is difficult to inject the electrolyte. Also, in the process of inserting the electrolyte injector into the cavity 33, interference may occur between the plain portion 32 in the vicinity of the core, and there may be a problem that the plain portion 32 is torn.

[0016] Also, the bent portions of the plain portions 10a and 11a where the current collectors 30 and 31 are welded overlap multiple times, and there should be no empty space (gap). Thereby, sufficient welding strength can be obtained, and even when using state-of-the-art technologies such as laser welding, it is possible to prevent problems such as the laser penetrating inside the electrode assembly A and melting the separator or the active material.

[0017] On the other hand, in the bent surface region formed while the plain portions 10a and 11a of the electrode assembly A are being bent, there is almost no gap through which the electrolyte can pass in the winding axis direction. This is because, in the process of bending the plain portions 10a and 11a, the gap between the winding turns that existed immediately after winding almost disappears. Therefore, in the structure in which the entire ends of the plain portions 10a and 11a are bent, there is a possibility that the impregnation time of the electrolyte increases.

[0018] In addition, in a conventional tabless cylindrical battery, a positive electrode plain portion 10a is entirely formed on the upper side of the electrode assembly A. Therefore, when the outer peripheral surface at the upper end of the battery housing is pushed inward to form a beading portion, the peripheral edge region 34 at the upper end of the electrode assembly A is compressed by the battery housing. Such compression may partially deform the electrode assembly A, and at this time, an internal short circuit may occur while the separator 12 is broken. If a short circuit occurs inside the battery, there is a risk of the battery generating heat or exploding. Summary of the Invention Problems to be Solved by the Invention

[0019] The present invention was conceived under the background of the above-described prior art, and an object of the present invention is to provide an electrode assembly having an improved structure of a plain portion that can relieve the stress applied to the plain portion when the plain portions exposed at both ends of the electrode assembly are bent.

[0020] Another object 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.

[0021] Still another object of the present invention is to provide an electrode assembly including a structure capable of preventing contact between the upper end peripheral edge of the electrode assembly and the inner surface of the battery housing when the upper end of the battery housing is beaded.

[0022] Still another object of the present invention is to provide an electrode assembly in which the physical properties of the welding region are improved by applying a segmented structure to the plain portion of the electrode, optimizing the dimensions (width, height, separation pitch) of the segments, and sufficiently increasing the number of stacked segments in the region used as the welding target region.

[0023] Still another object of the present invention is to provide an electrode assembly in which the energy density is improved and the resistance is reduced by applying a structure in which a current collector is welded to a wide area on the bent surface region formed by bending the segments.

[0024] Another object of the present invention is to provide an electrode assembly having a structure that enables stable welding of a current collector to the electrode assembly.

[0025] Another object of the present invention is to provide an electrode assembly with improved electrolyte impregnation characteristics.

[0026] Another object of the present invention is to provide a battery including a terminal and a current collector with an improved design so that electrical wiring can be performed at the top.

[0027] Another object of the present invention is to provide a battery including an electrode assembly with an improved structure, a battery pack including the battery, and an automobile including the battery pack.

[0028] The technical problems to be solved by the present invention are not limited to the above problems, and other problems will be clearly understood by those of ordinary skill in the art from the following description of the invention.

Means for Solving the Problems

[0029] To achieve the above problems, an electrode assembly according to an aspect of the present invention is an electrode assembly in which a first electrode, a second electrode, and a separation membrane interposed between the first electrode and the second electrode are wound around a winding axis to define a core and an outer peripheral surface. At least one of the first electrode and the second electrode includes an active material portion coated with an active material layer along the winding direction and a plain portion not coated with the active material layer.

[0030] At least a part of the plain portion can itself be used as an electrode tab.

[0031] The plain portion may include an insulating layer formed along the winding direction at a base end portion that is a boundary region with the active material layer.

[0032] The non-patterned portion may include a section that is divided into a plurality of divided sections that can be independently bent by a plurality of cutting grooves provided along the winding direction.

[0033] The gap between the bottom of the cutting groove and the insulating layer may vary along the winding direction.

[0034] When bending the divided section, the insulating layer can prevent deformation of the base end portion of the non-patterned portion by supporting the base end portion of the non-patterned portion. Since the rigidity of the base end portion is reinforced, when bending the divided section, the divided section can be accurately bent with reference to the lower end portion of the divided section.

[0035] At least a part of the insulating layer may be exposed outside the separation membrane. By covering the portion of the non-patterned portion that protrudes outside the separation membrane when bending the divided section with the insulating layer, it is possible to prevent a short circuit from occurring between adjacent electrodes of different polarities.

[0036] The insulating layer formed on the non-patterned portion may be thinner than the active material layer and may be disposed at a distance from the separation membrane. That is, while the active material layer is in contact with the separation membrane, there may be a gap between the insulating layer on the non-patterned portion and the separation membrane. Thereby, the insulating layer can minimize the influence of the deformation amount on the separation membrane even if the base end portion of the non-patterned portion is slightly deformed by the bending force when bending the divided section.

[0037] In a predetermined region of the electrode, the gap may increase or decrease compared to other regions.

[0038] In a predetermined region of the electrode, the gap may be constant along a direction parallel to the winding direction, or may gradually or stepwise increase along a direction parallel to the winding direction.

[0039] The gap may be from 0.2 mm to 4 mm.

[0040] The slit piece has a geometric shape in which the width in the winding direction decreases from the lower part to the upper part, and its lower inner angle can gradually or stepwise increase from the core side toward the outer peripheral side.

[0041] A plurality of the slit pieces may include a plurality of groups of slit pieces in which the lower inner angles of adjacent slit pieces in the winding direction are the same. Grouping and managing the slit pieces makes design and manufacturing management easy.

[0042] The lower inner angle θ of each of the slit pieces belonging to a certain group of slit pieces can be the same as or larger than the lower inner angle of each of the slit pieces belonging to the group of slit pieces arranged closer to the core side than it. In the jelly roll type electrode assembly, the curvature decreases toward the outer periphery. Therefore, for the slit pieces arranged closer to the outer periphery, by increasing their lower inner angles, the gap between adjacent slit pieces in the circumferential direction of the electrode assembly can be minimized, which helps to ensure the welding strength of the current collector described later.

[0043] A plurality of the slit pieces may include a plurality of groups of slit pieces in which a first element selected from the lower inner angle θ, the axial height H of the slit piece, the width D of the slit piece in the winding direction, the shape of the slit piece, the height of the bottom of the cutting groove between two slit pieces, and the separation pitch P between two slit pieces is the same for adjacent slit pieces in the winding direction.

[0044] Here, for the slit pieces belonging to different groups of slit pieces, the first element may be different.

[0045] When the first element is the lower inner angle of the slit piece, the lower inner angle of each of the slit pieces belonging to a certain group of slit pieces can be larger than the lower inner angle of each of the slit pieces belonging to the group of slit pieces arranged closer to the core side than it.

[0046] When the first element is the height in the axial direction of the segment (the winding shaft of the jelly roll type), the height of each segment belonging to one segment group can be higher than the height of each segment belonging to the segment group arranged closer to the core side. Then, when the segments arranged on the outer peripheral side are bent, the number of overlapping segments with the segments arranged closer to the core side can be further increased. In the radial direction of the electrode assembly, by maintaining the number of overlapping segments of the bent segments uniformly, a bending surface area suitable for welding of the current collector and easy to weld can be ensured.

[0047] When the first element is the width in the winding direction of the segment, the width in the winding direction of each segment belonging to one segment group can be wider than the width in the winding direction of each segment belonging to the segment group arranged closer to the core side. The electrode assembly wound in a jelly roll shape has a larger radius of curvature toward the outer peripheral side. Therefore, it is preferable that the width in the winding direction gradually increases so that the segments can be bent smoothly.

[0048] Segments belonging to the same segment group may be the same not only in the first element but also in a second element selected so as not to overlap with the first element from the lower inner angle of the segment, the axial height of the segment, the width in the winding direction of the segment, the shape of the segment, the height of the bottom of the cutting groove between two segments, and the separation pitch between two segments.

[0049] For example, the lower inner angle of the segment, the axial height of the segment, the width in the winding direction of the segment, the shape of the segment, the height of the bottom of the cutting groove between two segments, and the separation pitch between two segments of the segments belonging to the same segment group can all be substantially the same.

[0050] The segments belonging to different segment groups may have different second elements. For example, the lower inner angle of the segment, the axial height of the segment, and the width in the winding direction of the segments belonging to different segment groups may be different.

[0051] There may be a group separation interval Db between the plurality of the divided segment groups, which is larger than the separation pitch between the divided segments within the same divided segment group.

[0052] The group separation interval Db may provide an electrolyte impregnated portion that is not covered by the divided segments bent on the surface perpendicular to the axial direction of the electrode assembly. The region corresponding to the electrolyte impregnated portion is not welded to the current collector, and the impregnability of the electrolyte can be improved.

[0053] The divided segment groups separated by the group separation interval may be arranged radially with respect to the center of the electrode assembly to form a plurality of divided segment alignment portions. Also, the electrolyte impregnated portion formed by the region where the group separation interval is wound may also be arranged radially with respect to the center of the electrode assembly. Thereby, while surely securing a welding region with the current collector, a passage through which the electrolyte can be impregnated can be secured.

[0054] The divided segments included in the divided segment alignment portion may be bent in the radial direction toward the core of the electrode assembly to form a bent surface region in a plurality of separation regions.

[0055] The circumferential angle between the adjacent divided segment alignment portions (or bent surface regions) in the circumferential direction may be approximately 30°, 40°, 45°, 60°, 72°, 90°, 120°, or 180°. When the line connecting the geometric center of each divided segment alignment portion (or bent surface region) from the core center of the electrode assembly is defined as the angle measurement line, the angle is the angle between the adjacent angle measurement lines in the circumferential direction. The geometric center is the geometric center of the figure approximately formed by the outer periphery of the divided segment alignment portion (or bent surface region) when viewed from the axial direction of the divided segment alignment portion (or bent surface region). The geometric center may be the centroid of the corresponding figure.

[0056] The current collector may be welded to a plurality of bent surface regions. The welding locations may be 12, 9, 8, 6, 5, 4, 3, or 2 at equal intervals in the circumferential direction.

[0057] At least one of the group separation interval and the width in the winding direction of the segmented group may gradually or stepwise increase from the core toward the outer peripheral side. Thereby, the shape of the bent surface region formed by bending the segmented piece and / or the axial surface of the electrode assembly not covered by the segmented piece may be a fan shape substantially without a central region.

[0058] The plain portion may include 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 interposed between the first portion and the second portion.

[0059] The third portion may include the segmented piece.

[0060] The second portion may not have a slitting structure.

[0061] Preferably, at least one of the first portion and the second portion may have a relatively lower height in the winding axis direction than the third portion.

[0062] The first portion and the third portion may be directly connected without an intervening section connecting them or may be connected via an intervening section connecting them.

[0063] The third portion and the second portion may be directly connected without an intervening section connecting them or may be connected via an intervening section connecting them.

[0064] In the winding direction, the section of the first portion may start from the core side end.

[0065] In the winding direction, the length of the third portion may be longer than the lengths of the first portion and the second portion.

[0066] In the winding direction, the second portion may include at least the outermost final turn exposed on the outermost contour of the electrode assembly.

[0067] The height of the blank portion in a given section may mean the average height of the corresponding section or may mean the maximum height in the corresponding section.

[0068] The height of the first part may be constant along the winding direction. That is, the first part may not include a segmented slice.

[0069] In at least a partial section of the third part, the height of the segmented slice may increase from the core side toward the outer peripheral side.

[0070] At this time, the height of the segmented slice may increase stepwise.

[0071] Also, as the height increases stepwise, the length (width) in the winding direction of the section corresponding to each height may increase stepwise.

[0072] The second part may also include the segmented slice.

[0073] The segmented slice may be bent in the radial direction of the electrode assembly.

[0074] The segmented slice may be bent toward the core side, that is, in the centripetal direction, toward the central axis of the electrode assembly.

[0075] The first part does not include a segmented slice and may not be bent.

[0076] The final one turn may not include the segmented slice. Also, the height of the final one turn may be lower than that of the third part. When forming a jelly roll type electrode assembly, if there is a segmented slice bent in the final one turn, unexpected deformation of the segmented slice must be prevented, which makes the handling of the electrode assembly complicated. By removing the segmented slice in the final one turn, such complexity can be reduced.

[0077] A hollow portion extending in the axial direction is provided at the center of the electrode assembly, and the bent segmented slice does not have to block the hollow portion in the core side direction.

[0078] The bent third portion can overlap in the axial direction.

[0079] The bent third portion and the second portion can overlap in the axial direction.

[0080] The plurality of divided segments can each be trapezoidal.

[0081] In one form, at least a partial section of the third portion can have a height that gradually increases in the winding axis direction from the core side toward the outer peripheral side.

[0082] In another form, at least a partial section of the third portion can be divided into a plurality of divided segments.

[0083] The plain portion can be divided by a cutting groove extending axially inward (in the direction from the axial end of the electrode assembly toward the axial center) from the axial end of the winding axis. The shape of the cutting groove is determined by the shape of the side portions of the divided segments located on both sides of the cutting groove. When the plain portion is simply cut without removing at least a part of the plain portion at the notched portion through notching of the plain portion, the cutting line can also be regarded as a cutting groove.

[0084] In still another form, each of the plurality of divided segments can have a shape of a quadrilateral, trapezoid, triangle, parallelogram, semi - circle, or semi - ellipse.

[0085] In one embodiment, the plurality of divided segments are each trapezoidal, and the lower inner angles of the trapezoids of the plurality of divided segments can increase individually or in groups from the core side toward the outer peripheral side.

[0086] By the slitting piece, the axial extension length of the plain portion can vary along the winding direction. For the sake of convenience in explanation, if the axial extension length (the distance reaching the tip in the axial direction) of the plain portion at a predetermined position in the winding direction is simply referred to as the height, it will be clearly understood what it means that the height of the plain portion at the first winding direction position is higher than the height of the plain portion at the second winding direction position.

[0087] In the embodiment, when explaining the height of the plain portion, since the relative value of the height of the plain portion measured at different winding direction positions has more meaning than the absolute value of the height of the plain portion, the regulation regarding the line (zero point) serving as the reference for the height measurement will be omitted in the measurement of the height of the plain portion.

[0088] The height of the plain portion can be different at the portion corresponding to the upper end of the slitting piece, the portion corresponding to the cutting groove provided to form the slitting piece, and the portion corresponding to the bottom of the cutting groove. That is, even if the shape and size of the slitting piece and the shape and size of the cutting groove are the same, the height of the plain portion measured in the axial direction can vary depending on the measurement position determined in the winding direction. For example, it will be obvious that, roughly, the height of the plain portion at the winding direction position corresponding to the apex of the slitting piece is higher than the height of the plain portion at the winding direction position corresponding to the bottom of the cutting groove.

[0089] Also, the height of the upper end of each slitting piece can be different, the shape of each cutting groove can be different, and the height of the bottom of the cutting groove can also be different. That is, since the shape and size of the slitting piece and the shape and size of the cutting groove can change, the height of the plain portion measured in the axial direction can vary depending on the measurement position determined along the winding direction.

[0090] On the other hand, the height of the slitting piece can be defined by the axial distance (H) from the bottom of the cutting groove defining the corresponding slitting piece to the tip of the corresponding slitting piece. When the heights of the bottoms of the cutting grooves on both sides are different with respect to the slitting piece as a reference, the height of the slitting piece can be defined by the axial distance from the average height point of the heights of the bottoms of the cutting grooves on both sides to the tip of the slitting piece.

[0091] Preferably, at least one of the height in the winding axis direction and the width in the winding direction of the plurality of the segmented slices may increase stepwise from the core side toward the outer peripheral side, either individually or for each group.

[0092] Preferably, each of the plurality of the segmented slices may satisfy at least one of the following conditions: a width condition of 1 mm to 11 mm in the winding direction, a height condition of 2 mm to 10 mm in the winding axis direction, and a separation pitch condition of 0.05 mm to 1 mm in the winding direction.

[0093] Preferably, there is a gap between the bottom of the cutting groove of the segmented slice and the active material layer, and the gap may be 0.2 mm to 4 mm.

[0094] Preferably, the plurality of the segmented slices form a plurality of segmented slice groups from the core side toward the outer peripheral side, and the segmented slices belonging to the same segmented slice group may have at least one of the width in the winding direction, the height in the winding axis direction, and the separation pitch in the winding direction being the same.

[0095] Preferably, in the radial direction of the electrode assembly, when the widths in the winding direction of three continuously adjacent segmented slice groups are W1, W2, and W3, respectively, it may include a combination of segmented slice groups in which W3 / W2 is smaller than W2 / W1.

[0096] Preferably, the segmented slices belonging to the same segmented slice group may have at least one of the width in the winding direction, the height in the winding axis direction, and the separation pitch in the winding direction increasing stepwise from the core side toward the outer peripheral side.

[0097] In one embodiment, at least a part of the plurality of segmented slice groups may be arranged in the same winding turn of the electrode assembly.

[0098] In another embodiment, the first part or the second part may not have a plain cutting structure.

[0099] The segmented slice may be bent in the radial direction.

[0100] All of the plurality of divided segments can be bent.

[0101] Some of the plurality of divided segments may not need to be bent.

[0102] Preferably, the plurality of divided segments can be multiply overlapped along the winding axis direction while being bent toward the core side.

[0103] Preferably, a cavity is provided in the core of the electrode assembly, and the cavity can be opened without being blocked by a plurality of divided segments bent toward the core side.

[0104] Therefore, the radial length R of the first portion and the bending length H of the innermost divided segment of the third portion can satisfy the relational expression "H≦R".

[0105] In one embodiment, the height of the second portion can gradually or stepwise decrease from the core side toward the outer peripheral side.

[0106] In one embodiment, the second portion is divided into a plurality of divided segments, and at least one of the width in the winding direction, the height in the winding axis direction, and the separation pitch in the winding direction of the plurality of divided segments included in the second portion can be larger than those of the plurality of divided segments included in the third portion.

[0107] Taking a virtual straight line drawn along the winding direction (outer peripheral direction) corresponding to the height of the bottom of the cutting groove as a reference line DL, the reference line can be a straight line parallel to the winding direction (X-axis) of the plain portion.

[0108] The reference line can be arranged at a position corresponding to the bottom of the cutting groove provided between two adjacent divided segments for forming the divided segments.

[0109] The heights of the bottoms of the plurality of cutting grooves can correspond to each other in the winding axis direction. In such a case, the position of the reference line can be defined at a position corresponding to the bottom of the cutting groove.

[0110] The heights of the bottoms of the plurality of the cutting grooves may be different.

[0111] When most (for example, 50% or more) of the bottoms of the plurality of cutting grooves are located at a specific height and only the heights of the bottoms of some of the cutting grooves are different from the specific height, the position of the reference line can be determined corresponding to the specific height. That is, in such a case, the reference line can be determined based on the height of the bottom of the cutting groove that occupies the maximum length in the winding direction. For example, if about 2 / 3 of the total length occupied by the bottoms of the cutting grooves in the winding direction is the first height and the height of the bottom of the cutting groove corresponding to the remaining 1 / 3 is different from the first height, the reference line can be defined at a position corresponding to the first height.

[0112] When the heights of the bottoms of the plurality of cutting grooves are not concentrated at a specific height (when the ratio of the non-patterned section where the cutting groove having the maximum frequency height is formed is less than 50% of the total length of the electrode), the reference line can be set to be located at the average height of the heights of the bottoms of the plurality of the cutting grooves. For example, when measuring the height with the boundary point between the active material layer and the non-patterned section as a reference, if the length occupied by the non-patterned section with the bottom height of the cutting groove being 2 mm is 30% of the total length of the electrode, the length occupied by the non-patterned section with the bottom height of the cutting groove being 3 mm in the winding direction is 30% of the total length of the electrode, and the length occupied by the non-patterned section with the bottom height of the cutting groove being 4 mm in the winding direction is 40% of the total length of the electrode, the reference line can be located at a height of 2×0.3 + 3×0.3 + 4×0.4, which is 3.1 mm.

[0113] The position of the end SL in the width direction (Y-axis) of the separation membrane can be regulated in relation to the reference line DL.

[0114] Among the plurality of the divided sections, the divided section with the lowest height is referred to as the minimum divided section.

[0115] When determining the lowest-height segment, segments that cannot be bent may be excluded. That is, the minimum segment may mean the segment with the lowest height among the bent segments included in the bent surface area. The bent surface area means the area of the end face of the electrode assembly where the segments are folded multiple times along the winding axis direction while being bent in the radial direction.

[0116] The minimum segment can be determined from among the segments that can be bent.

[0117] If the height of the segment is less than 2 mm, there is a risk that the segment cannot be smoothly bent due to interference between the separation membrane and the segment.

[0118] Therefore, the minimum segment can be determined from among the segments having a height of 2 mm or more.

[0119] If the height of the segment is less than 3 mm, there is a risk that it cannot be smoothly bent in the intended direction during the bending process, or that forming in an unintended direction may occur.

[0120] Therefore, the minimum segment can be determined from among the segments having a height of 3 mm or more.

[0121] If the height of the segment is less than 4 mm, there is a risk that the welding between the segments and / or the welding between the current collector and the segment may be incomplete.

[0122] Therefore, the minimum segment can be determined from among the segments having a height of 4 mm or more.

[0123] If the height of the segment is 5 mm or more, reliable bending is possible in the bending process even considering manufacturing errors and the like.

[0124] Therefore, the minimum segment can be determined from among the segments having a height of 5 mm or more.

[0125] The end SL in the width direction of the separation membrane is located in the outer direction of the electrode assembly within 30% of the height Ha of the minimum segmentation piece with reference to the reference line DL, or can be located in the inner direction of the electrode assembly within 30% of the height of the minimum segmentation piece.

[0126] That is, the position of the end in the width direction of the separation membrane can exist within the range of "DL ± 0.3Ha".

[0127] The end SL in the width direction of the separation membrane is located in the outer direction of the electrode assembly within 1.5 mm with reference to the reference line DL, or can be located in the inner direction of the electrode assembly within 1.5 mm.

[0128] That is, the position of the end SL in the width direction of the separation membrane can exist within the range of "DL ± 1.5 mm".

[0129] The end SL in the width direction of the separation membrane is located in the outer direction of the electrode assembly within 1.2 mm with reference to the reference line DL, or can be located in the inner direction of the electrode assembly within 1.2 mm.

[0130] That is, the position of the end SL in the width direction of the separation membrane can exist within the range of "DL ± 1.2 mm".

[0131] The end SL in the width direction of the separation membrane is located in the outer direction of the electrode assembly within 0.9 mm with reference to the reference line DL, or can be located in the inner direction of the electrode assembly within 0.9 mm.

[0132] That is, the position of the end SL in the width direction of the separation membrane can exist within the range of "DL ± 0.9 mm".

[0133] The end SL in the width direction of the separation membrane is located in the outer direction of the electrode assembly within 0.6 mm with reference to the reference line DL, or can be located in the inner direction of the electrode assembly within 0.6 mm.

[0134] That is, the position of the end SL in the width direction of the separation membrane may be within the range of "DL ± 0.6 mm".

[0135] The position of the end SL in the width direction of the separation membrane may be within the range of "DL ± 0.3 Ha" and "DL ± 1.5 mm".

[0136] The position of the end SL in the width direction of the separation membrane may be within the range of "DL ± 0.3 Ha" and "DL ± 1.2 mm".

[0137] The position of the end SL in the width direction of the separation membrane may be within the range of "DL ± 0.3 Ha" and "DL ± 0.9 mm".

[0138] The position of the end SL in the width direction of the separation membrane may be within the range of "DL ± 0.3 Ha" and "DL ± 0.6 mm".

[0139] The separation membrane may include a porous polymer substrate and a porous coating layer located on the surface of the porous polymer substrate and containing inorganic particles and a binder polymer.

[0140] The porous coating layer may be located on both surfaces of the porous polymer substrate.

[0141] The plurality of the divided sections may have a predetermined separation pitch.

[0142] The separation pitch may be defined by the distance between the lower end corners of two adjacent divided sections.

[0143] The separation pitch may be 0.5 mm or more. If the separation pitch is less than 0.5 mm, stress may be concentrated and cracks may occur at the bottom of the corresponding cutting groove during processes such as processing, winding, or bending.

[0144] The lower end corners of two divided sections may be directly connected. That is, the bottom part of the cutting groove may be a flat linear shape extending in the winding direction (X-axis).

[0145] A round reinforcing portion can be added to the lower end corner portion.

[0146] The radius r of the round reinforcing portion can be 0.02 mm or more. If the corresponding radius is 0.02 mm or more, the effect of stress dispersion can be surely brought about.

[0147] The radius of the round reinforcing portion can be 0.1 mm or less. If the corresponding radius exceeds 0.1 mm, the effect of stress dispersion will not increase further, and there is a possibility that the space near the bottom of the cutting groove will decrease and the impregnation property of the electrolyte will be inhibited.

[0148] The separation pitch can be 1 mm or less. If the separation pitch exceeds 1 mm, the impregnation property will not increase, and instead, there may be a gap between the bent segment pieces and the current collector may not be sufficiently welded.

[0149] The separation pitch can be determined in relation to the width measured in the winding direction of the adjacent segment pieces that define it.

[0150] For example, as the width in the winding direction of the segment pieces increases, the separation pitch between the segment pieces may tend to increase. Thereby, the impregnation property of the electrolyte can be made uniform.

[0151] The width in the winding direction of the segment pieces may tend to gradually increase from the core side to the outer peripheral side of the electrode assembly.

[0152] The width in the winding direction of the segment pieces can gradually or stepwise increase from the core side to the outer peripheral side of the electrode assembly.

[0153] Thereby, the separation pitch can also gradually or stepwise increase from the core side to the outer peripheral side of the electrode assembly.

[0154] To achieve the above object, a battery according to another aspect of the present invention includes a first electrode, a second electrode, and a separator interposed between the first electrode and the second electrode, which are wound around a winding axis to define a core and an outer peripheral surface, an electrode assembly; a battery housing that houses the electrode assembly and is electrically connected to one of the first electrode and the second electrode to have a first polarity; a sealing body that seals an open end of the battery housing; and a terminal that is electrically connected to the other of the first electrode and the second electrode and has a second polarity with its surface exposed to the outside.

[0155] Preferably, at least one of the first electrode and the second electrode may include a plain portion at a long-side end where the active material layer is not coated.

[0156] Preferably, at least a part of the plain portion itself is used as an electrode tab, and the plain 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 interposed between the first portion and the second portion, and at least one of the first portion and the second portion may be relatively lower in height in the winding axis direction than the third portion.

[0157] In one embodiment, the second portion is relatively lower in height in the winding axis direction than the third portion, the battery housing includes a beading portion pushed inward at an end adjacent to the open end, and an inner peripheral surface of the beading portion facing a peripheral edge of an upper end of the electrode assembly and the second portion may be separated by a predetermined distance.

[0158] Preferably, a pushing depth D1 of the beading portion and a distance D2 from an inner peripheral surface of the battery housing to a boundary point between the second portion and the third portion may satisfy the relational expression "D1 ≦ D2".

[0159] In one embodiment, a battery according to one aspect of the present invention may further include a current collector electrically coupled to the third portion, and an insulator covering the current collector and having a periphery fixed between the inner peripheral surface of the beading portion and the current collector.

[0160] In another embodiment, the diameter of the current collector and the outermost diameter of the third portion are smaller than the minimum inner diameter of the inner peripheral surface of the beading portion, and the diameter of the current collector can be the same as or larger than the outermost diameter of the third portion.

[0161] In yet another embodiment, the current collector can be positioned higher than the beading portion.

[0162] Preferably, at least a partial section of the third portion is bent from the outer peripheral side to the core side, a cavity is provided in the core of the electrode assembly, and the cavity can be open to the outside without being blocked by the bending structure of the third portion.

[0163] Therefore, the third portion includes a plurality of divided sections divided along the winding direction of the electrode assembly, the plurality of divided sections are bent from the outer peripheral side to the core side, and the radial length R of the first portion and the bending length H of the divided section located at the innermost side of the third portion can satisfy the relational expression "H≦R".

[0164] Preferably, each of the plurality of divided sections can have a shape of a quadrilateral, a trapezoid, a triangle, a parallelogram, a semi-circular shape, or a semi-elliptical shape.

[0165] Preferably, each of the plurality of divided sections can satisfy at least one of the conditions of a width condition of 1 mm to 11 mm in the winding direction, a height condition of 2 mm to 10 mm in the winding axis direction, and a separation pitch condition of 0.05 mm to 1 mm in the winding direction.

[0166] Preferably, a gap exists between the bottom of the cutting groove of the divided section and the active material layer, and the gap can be 0.2 mm to 4 mm.

[0167] Preferably, the plurality of the segmented pieces form a plurality of groups, and at least one of the width in the winding direction, the height in the winding axis direction, and the separation pitch in the winding direction of the segmented pieces belonging to each group is the same, and at least one of the plurality of groups can constitute the same winding turn of the electrode assembly.

[0168] Preferably, in the radial direction of the electrode assembly, when the widths in the winding direction of three continuously adjacent segmented piece groups are W1, W2, and W3 respectively, it may include a combination of segmented piece groups in which W3 / W2 is smaller than W2 / W1.

[0169] In one embodiment, the sealing body includes a cap that seals the open end of the battery housing and a gasket that wraps around the periphery of the cap and is crimped to the upper end portion of the battery housing, and the terminal having the second polarity can be the cap.

[0170] In another embodiment, the battery according to one aspect of the present invention may further include a current collector that is electrically connected to the non-coated portion of the second electrode having the first polarity and at least a part of the periphery of which is coupled to the side wall of the battery housing. In this case, the sealing body includes a non-polar cap and a gasket that wraps around the periphery of the cap and is crimped to the upper end portion of the battery housing, the battery housing is insulatingly attached to a through hole formed in the center of the closed surface, and includes a rivet terminal that is electrically connected to the first electrode and has the second polarity.

[0171] The technical problem according to the present invention is achieved by a battery pack including a plurality of the above-described batteries.

[0172] Preferably, the ratio of the height to the diameter of the battery can be greater than 0.4.

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

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

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

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

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

[0178] The technical problem according to the present invention is also achieved by an automobile including the above-described battery pack.

Advantages of the Invention

[0179] According to one aspect of the present invention, by using the plain portions protruding above and below the electrode assembly as electrode tabs, the internal resistance of the battery can be reduced and the energy density can be increased.

[0180] Also, according to one aspect of the present invention, by improving the structure of the plain portion of the electrode assembly, interference between the electrode assembly and the inner peripheral surface of the battery housing can be avoided during the process of forming the beading portion of the battery housing, and internal short circuits of the cylindrical battery due to partial deformation of the electrode assembly can be prevented.

[0181] Further, according to one aspect of the present invention, by improving the structure of the non-patterned portion of the electrode assembly, it is possible to prevent the non-patterned portion from being torn when bent, and to sufficiently increase the number of stacked layers of the non-patterned portion to improve the welding strength of the current collector.

[0182] Also, according to one aspect of the present invention, by applying a segmented structure to the non-patterned portion of the electrode and optimizing the dimensions (width, height, separation pitch) of the segments, the number of stacked layers of the segments in the region used as the welding target region can be sufficiently increased, thereby improving the physical properties of the region where the current collector is welded.

[0183] Further, according to one aspect of the present invention, by applying a structure in which the current collector is welded over a wide area to the bent surface region formed by bending the segments, it is possible to provide an electrode assembly with improved energy density and reduced resistance.

[0184] Also, according to one aspect of the present invention, it is possible to provide a cylindrical battery with an improved design so that electrical wiring can be performed at the top.

[0185] Further, according to one aspect of the present invention, by improving the structure of the non-patterned portion adjacent to the core of the electrode assembly, it is possible to prevent the cavity in the core of the electrode assembly from being blocked when the non-patterned portion is bent, and to easily perform the electrolyte injection process and the welding process between the battery housing (or terminal) and the current collector.

[0186] Also, according to one aspect of the present invention, by providing the bent surface region formed while the segments of the non-patterned portion are bent corresponding to the welding site with the current collector, the welding of the current collector can be stably performed and the impregnation property of the electrolyte can be ensured.

[0187] Also, according to one aspect of the present invention, even when the non-patterned portion of the electrode assembly is bent, the impregnation property of the electrolyte can be sufficiently ensured.

[0188] Further, according to one aspect of the present invention, it is possible to provide a cylindrical battery having a structure with low internal resistance, prevention of internal short circuit, and improved welding strength between the current collector and the plain portion, a battery pack including the cylindrical battery, and an automobile.

[0189] In particular, the present invention can provide a cylindrical battery having a ratio of height to diameter of 0.4 or more and a resistance of 4 mΩ or less, a battery pack including the cylindrical battery, and an automobile.

[0190] The present invention also has various other effects, which will be described later with reference to embodiments. However, effects that can be easily inferred by an ordinary technician will be omitted from the description.

[0191] The following drawings attached to this specification illustrate preferred embodiments of the present invention and are for the purpose of further understanding the technical idea of the present invention together with the detailed description of the invention. Therefore, the present invention should not be construed as being limited only to the matters described in the drawings.

Brief Description of the Drawings

[0192]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7a

Figure 7b

Figure 7c

Figure 7d

Figure 7e

Figure 7f

Figure 7g

Figure 7h

Figure 7i

Figure 7j

Figure 8a

Figure 8b

Figure 8c

Figure 9

Figure 10a

Figure 10b

Figure 10c

Figure 10d

Figure 10e

Figure 10f

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

Figure 18

Figure 19

Figure 20

Figure 21

Figure 22

Figure 23

Figure 24

Figure 25

Figure 26

Figure 27

Figure 28

Figure 29

Figure 30

Figure 31

Embodiments for Carrying out the Invention

[0193] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, the terms and words used in this specification and the claims are not to be construed as being limited to their ordinary and dictionary meanings, and the inventor himself interprets 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.

[0194] Therefore, it should be understood that the embodiments described in this specification and the configurations shown in the drawings are merely the most preferred embodiments of the present invention and do not represent all of the technical ideas of the present invention, and there may be various equivalents and modifications that can replace them at the time of this application.

[0195] Also, for the purpose of assisting in the understanding of the invention, the attached drawings are not illustrated to 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.

[0196] The expression that two comparison targets are the same means "substantially the same". Therefore, "substantially the same" may include cases having a deviation regarded as a low level in the industry, for example, a deviation within 5%. Also, the fact that a certain parameter is uniform in a predetermined region means that it is uniform from an average point of view in the corresponding region.

[0197] Also, terms such as "first", "second", etc. are used to indicate various components, but 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.

[0198] Throughout the specification, unless otherwise specified, each component can be in the singular or plural.

[0199] The statement that any configuration is disposed "above (or below)" a component or "on (or under)" a component means not only that any configuration is disposed in contact with the upper surface (or lower surface) of the component, but also that other configurations can be interposed between the component and any configuration disposed above (or below) the component.

[0200] Also, when it is stated that a certain component is "connected", "coupled", or "joined" to another component, it includes not only the case where the components are directly connected or joined to each other, but also the case where other components are "interposed" between the components, or the case where each component is "connected", "coupled", or "joined" through other components.

[0201] Also, the singular expressions used in this specification include plural expressions unless the context clearly indicates a different meaning. In this application, terms such as "configured" or "including" are not construed as necessarily including all of the many components or many steps described in the specification, and some of the components or steps may not be included, and additional components or steps may be further included.

[0202] Throughout the specification, unless otherwise specified, "A and / or B" means A, B, or A and B, and "C to D" means C or more and D or less.

[0203] In this specification, for convenience of explanation, the direction along the length direction of the winding axis of the electrode assembly wound in a jelly roll shape is referred to as the axial direction (Y-axis). Further, the direction surrounding the winding axis is referred to as the circumferential direction or the outer circumferential direction (X-axis). Further, the direction approaching or moving away from the winding axis is referred to as the radial direction or the radial direction. Among these, in particular, the direction approaching the winding axis is referred to as the centripetal direction, and the direction moving away from the winding axis is referred to as the centrifugal direction.

[0204] First, an electrode assembly according to an embodiment of the present invention will be described. The electrode assembly may be a jelly roll type electrode assembly having a structure in which a sheet-like first electrode, a second electrode, and a separation membrane interposed between the first electrode and the second electrode are wound in one direction. However, the present invention is not limited by the type of the electrode assembly.

[0205] Preferably, at least one of the first electrode and the second electrode includes a plain portion where the active material is not coated at the long side end portion in the winding direction. At least a part of the plain portion itself 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 peripheral side plain portion adjacent to the outer peripheral surface of the electrode assembly, and an intermediate plain portion interposed between the core side plain portion and the outer peripheral side plain portion.

[0206] Preferably, at least one of the core side plain portion and the outer peripheral side plain portion is relatively lower in height than the intermediate plain portion.

[0207] FIG. 4 is a plan view showing the structure of the electrode 40 according to the first embodiment of the present invention.

[0208] Referring to FIG. 4, the electrode 40 of the first embodiment includes a current collector 41 made of a metal foil and an active material layer 42. The metal foil can 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-axis). The electrode 40 includes a non-coated portion 43 at the long-side end in the winding direction (X-axis). The non-coated portion 43 is a partial region of the current collector 41 that is not coated with the active material. The region of the current collector 41 where the active material layer 42 is formed can be referred to as the active material portion.

[0209] In the 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%.

[0210] Preferably, in the electrode 40, the width of the active material portion in the short-side direction of the current collector 41 can be 60 mm to 70 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 1.2% to 2.3%.

[0211] The ratio of the short side to the long side of the active material portion is significantly smaller than 6% to 11%, which is the ratio of the short side to the long side of the active material portion of the electrode used in a cylindrical battery having a form factor of 1865 or 2170.

[0212] Preferably, the current collector 41 can have an elongation of 1.5% to 3.0% and a tensile strength of 25 gf / mm 2 ~35 kgf / mm 2 The elongation and tensile strength can be measured according to the measurement method of IPC-TM-650. The electrode 40 is manufactured by forming the active material layer 42 on the current collector 41 and then pressing. During pressing, the elongation rates of the non-coated portion 43 region and the active material layer 42 region are different. Therefore, after pressing, the electrode 40 has a swell, and the swell becomes more severe as the electrode 40 becomes longer.

[0213] When optimizing the elongation and tensile strength of the current collector 41, when the length of the electrode 40 is at the 4m level, the length of the canvas after crimping is reduced to less than 20 mm. The canvas length is the maximum amount of deflection of the electrode 40 in the winding direction (X-axis) when the wavy electrode 40 is expanded. The maximum amount of deflection can be measured at the outer peripheral side terminal. Since the electrode 40 with the optimized elongation and tensile strength of the current collector 41 has a short canvas length, no meandering defect occurs during the notching operation of the plain part 43 or the winding process of the electrode 40.

[0214] The lower the elongation of the current collector 41, the easier it is to break. When the elongation of the current collector 41 is less than 1.5%, the rolling processability of the current collector 41 decreases, and when crimping the electrode 40 coated with the active material layer 42 on the current collector 41, there is a risk of disconnection in the current collector 41. On the other hand, when the elongation of the current collector 41 exceeds 3.0%, the active material part of the electrode 40 is excessively stretched and the canvas length increases significantly. When the tensile strength of the current collector 41 is less than 25 kgf / mm 2 or exceeds 35 kgf / mm 2 the electrode processability of the electrode 40 decreases.

[0215] The canvas phenomenon becomes particularly problematic in the positive electrode current collector made of aluminum foil. By using an aluminum foil with an elongation of 1.5% to 3.0% and a tensile strength of 25 kgf / mm 2 to 35 kgf / mm 2 as the current collector according to the present invention, the canvas phenomenon can be suppressed. It is preferable to form an active material layer on such a current collector and use it as a positive electrode.

[0216] Preferably, an insulating coating layer 44 may be formed at the boundary between the active material layer 42 and the plain portion 43. Hereinafter, for convenience of explanation, the insulating coating layer 44 is also simply referred to as the insulating layer 44. The insulating coating layer 44 is formed so that at least a part thereof overlaps the boundary between the active material layer 42 and the plain portion 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 portion 43 with a width of 0.3 mm to 5 mm. The width of the insulating coating layer 44 may vary along the winding direction of the electrode 40. The insulating coating layer 44 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 portion because it is not an area coated with the active material layer.

[0217] The plain portion 43 includes a core-side plain portion B1 adjacent to the core side of the electrode assembly, an outer-periphery-side plain portion B3 adjacent to the outer periphery side of the electrode assembly, and an intermediate plain portion B2 interposed between the core-side plain portion B1 and the outer-periphery-side plain portion B3.

[0218] The core-side plain portion B1, the outer-periphery-side plain portion B3, and the intermediate plain portion B2 can be defined as the plain portion of the region adjacent to the core side, the plain portion of the region adjacent to the outer periphery side, and the plain portion of the other regions excluding these, respectively, when the electrode 40 is wound as a jelly-roll type electrode assembly.

[0219] Hereinafter, the core-side plain portion B1, the outer-periphery-side plain portion B3, and the intermediate plain portion B2 are respectively referred to as the first portion, the second portion, and the third portion.

[0220] As an example, the first portion B1 is the plain portion of the electrode region including the innermost winding turn, and the second portion may be the plain portion of the electrode region including the outermost winding turn. The winding turns can be counted based on the core-side end portion of the electrode assembly.

[0221] As another example, the boundary between B1 / B2 can be appropriately defined at a point where the height (or change pattern) of the blank portion substantially changes from the core side to the outer peripheral side of the electrode assembly, or at a point of a predetermined percentage (e.g., 5%, 10%, 15% of the radius, etc.) based on the radius of the electrode assembly.

[0222] The boundary between B2 / B3 can be defined at a point where the height (or change pattern) of the blank portion substantially changes from the outer peripheral side to the core side of the electrode assembly, or at a point of a predetermined percentage (e.g., 85%, 90%, 95% of the radius, etc.) based on the radius of the electrode assembly. Once the boundaries of B1 / B2 and B2 / B3 are specified, the third portion B2 can be automatically specified.

[0223] If only the boundary of B1 / B2 is specified, the boundary of B2 / B3 can be appropriately selected at a point near the outer peripheral side of the electrode assembly. As an example, the second portion can be defined as the blank portion of the electrode region constituting the outermost winding turn. On the other hand, if only the boundary of B2 / B3 is specified, the boundary of B1 / B2 can be appropriately selected at a point near the core side of the electrode assembly. As an example, the first portion can be defined as the blank portion of the electrode region constituting the innermost winding turn.

[0224] It does not exclude the presence of other structures between the first portion B1 and the third portion B2. Nor does it exclude the presence of other structures between the third portion B2 and the second portion B3.

[0225] In the first embodiment, the height of the blank portion 43 is not constant and is relatively different in the winding direction (X-axis). That is, the height (length in the Y-axis direction) of the second portion B3 is 0 or more and is relatively lower than that of the first portion B1 and the third portion B2. Here, the height of each portion can be the average height or the maximum height, and the same applies hereinafter. In the winding direction, the length of the third portion B2 is even longer than that of the first portion B1 and the second portion B3.

[0226] FIG. 5 is a plan view showing the structure of the electrode 45 according to the second embodiment of the present invention.

[0227] Referring to FIG. 5, the electrode 45 of the second embodiment is different from that of the first embodiment only in that the height of the second portion B3 gradually decreases toward the outer peripheral side, and other configurations are substantially the same.

[0228] In a modified form, the second portion B3 can be deformed into a stepped shape (refer to the dotted line) in which the height decreases stepwise.

[0229] FIG. 6 is a plan view showing the structure of an electrode 50 according to the third embodiment of the present invention.

[0230] Referring to FIG. 6, in the electrode 50 of the third embodiment, the heights of the first portion B1 and the second portion B3 are 0 or more, and are relatively lower than that of the third portion B2. Also, the height of the first portion B1 and the height of the second portion B3 may be the same or different.

[0231] Preferably, the height of the third portion B2 may be in a stepped shape that gradually increases from the core side toward the outer peripheral side.

[0232] Patterns 1 to 7 divide the third portion B2 centering on the position where the height of the blank portion 43 changes. Preferably, the number of patterns, the height (length in the Y-axis direction) and the width (length in the X-axis direction) of each pattern can be adjusted so as to maximize the dispersion of stress during the bending process of the blank portion 43. The dispersion of stress is for preventing the blank portion 43 from being broken when it is bent toward the core side of the electrode assembly.

[0233] The width d of the first portion B1 B1 is designed by applying the condition that the core of the electrode assembly is not blocked when the pattern of the third portion B2 is bent toward the core side. The core means a cavity existing at the winding center of the electrode assembly.

[0234] As an example, the width d of the first portion B1 B1 can increase in proportion to the bending length of Pattern 1. The bending length corresponds to the height of the pattern based on the bending point of the pattern.

[0235] Preferably, the width d of the first portion B1 B1 can be set such that the radial width of the winding turn formed by the first portion B1 is equal to or greater than the bending length of Pattern 1. In a modified example, the width d of the first portion B1 B1 can be set such that the value obtained by subtracting the radial width of the winding turn formed by the first portion B1 from the bending length of Pattern 1 is less than 0 or equal to 10% of the core radius.

[0236] In a specific example, when the electrode 50 is used to manufacture the electrode assembly of a cylindrical battery with a form factor of 4680, the width d of the first portion B1 B1 can be set to 180 mm to 350 mm according to the diameter of the core of the electrode assembly and the bending length of Pattern 1.

[0237] In one example, the width of each pattern can be designed to form one or more winding turns of the electrode assembly.

[0238] In another example, the height of the third portion B2 can be in a stepped shape that increases from the core side towards the outer peripheral side and then decreases.

[0239] In still another example, the second portion B3 can be deformed to have the same structure as that of the second embodiment.

[0240] In still another example, the pattern structure applied to the third portion B2 can be extended to the second portion B3 (refer to the dotted line).

[0241] The third portion B2 can be bent in the radial direction of the electrode assembly with respect to an imaginary line connecting the tip of the first portion B1 and the tip of the second portion B3 in the winding direction.

[0242] FIG. 7a is a plan view showing the structure of the electrode 60 according to the fourth embodiment of the present invention.

[0243] Referring to FIG. 7a, the electrode 60 of the fourth embodiment has a height in the winding axis (Y-axis) direction of the first portion B1 and the second portion B3 that is 0 or more, and is relatively lower than that of 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-axis) direction may be the same or different.

[0244] Preferably, at least a partial section of the third portion B2 may include a plurality of segmented slices 61. The plurality of segmented slices 61 may have a height that increases stepwise from the core side toward the outer peripheral side. The plurality of segmented slices 61 have the form of a geometric figure whose width decreases from the lower part to the upper part. Preferably, the geometric figure is a trapezoid. The corners of the trapezoid, i.e., the apex sites, may not be sharp ends but may be rounded or chamfered like a chamfer. As will be described later, the form of the geometric figure can be variously deformed.

[0245] The segmented slice 61 may be formed by laser notching. The segmented slice 61 can be formed by known metal foil cutting processes such as ultrasonic cutting or punching.

[0246] The third portion B2 can be bent in the radial direction of the electrode assembly with respect to a virtual line connecting the tip of the first portion B1 and the tip of the second portion B3 in the winding direction. At this time, the segmented slice 61 can be bent with respect to the bottom of the cutting groove. The height of the bottom of the cutting groove between the segmented slices can correspond to the height of the first portion B1 and / or the second portion B3.

[0247] In the fourth embodiment, when bending the plain portion 43, in order to prevent damage to the active material layer 42 and / or the insulating coating layer 44, it is preferable to provide a predetermined gap between the bottom of the cutting groove (G in FIG. 7b) between the segmented slices 61 and the active material layer 42. This is because when the plain portion 43 is bent, stress is concentrated near the bottom of the cutting groove 63.

[0248] The gap can vary along the winding direction of the electrode 60. The gap is 0.2 mm to 4 mm, preferably 1.5 mm to 2.5 mm.

[0249] When the electrode 60 is the negative electrode, it is more preferable that the gap is 1.0 mm or more, and when the electrode 60 is the positive electrode, it is more preferable that the gap is 2.0 mm or more.

[0250] By adjusting the gap within the above numerical range, it is possible to prevent the active material layer 42 and / or the insulating coating layer 44 near the bottom of the cutting groove 63 from being damaged by the stress generated during the bending process of the plain portion 43.

[0251] Preferably, when the electrode 40 is wound as an electrode assembly, at least a part of the insulating coating layer 44 can be exposed outside the separator. In this case, when the segmented piece 61 is bent, the insulating coating layer 44 can support the bending point.

[0252] The gap can prevent damage to the active material layer 42 and / or the insulating coating layer 44 due to the tolerance during the notching or cutting of the segmented piece 61. In one direction parallel to the winding direction, the gap can be substantially the same or variable. In the latter case, the plurality of segmented pieces can have variable gaps individually, in group units, or in two or more group units along one direction parallel to the winding direction.

[0253] The lower end portion of the segmented piece 61 formed by the cutting groove 63 can be a portion where bending is induced in the bending process of the segmented piece 61. That is, in the bending process, the bend resistance is almost constant from the lowermost end of the plain portion 43 to near the bottom of the cutting groove 63, rapidly decreases near the bottom of the cutting groove 63, and then is almost constant until reaching the upper end portion of the segmented piece 61.

[0254] The bottom of the cutting groove 63 and the insulating coating layer 44 can be separated by 0.2 mm to 2.0 mm. If the separation distance is less than 0.2 mm, the above-described damage prevention effect cannot be fully exerted. If the separation distance is greater than 2.0 mm, the damage prevention effect does not increase, and there is a possibility of reducing the bending support effect of the insulating coating layer 44.

[0255] In a direction parallel to the winding direction, the separation distance between the bottom of the cutting groove 63 and the insulating coating layer 44 may be substantially the same or variable. In the latter case, the separation distance of the plurality of divided segments may vary individually, in group units, or in two or more group units along a direction parallel to the winding direction.

[0256] When the electrode 60 is wound, the end portion of the insulating coating layer 44 in the winding axis (Y-axis) direction may be positioned in the range of -2 mm to 2 mm along the winding axis direction with reference to the end portion of the separation film. The insulating coating layer 44 can prevent a short circuit between two electrodes of opposite polarities facing each other with the separation film interposed therebetween, and support the bending point when the divided segment 61 is bent. To improve the short circuit prevention effect between the two electrodes, the insulating coating layer 44 may be exposed outside the separation film. Further, 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 portion of the insulating coating layer 44 in the winding axis (Y-axis) direction is positioned above the bottom of the cutting groove 63. In one example, the end portion of the insulating coating layer 44 in the winding axis direction may be positioned within the range of -2 mm to +2 mm with reference to the bottom of the cutting groove 63. The thickness of the insulating coating layer 44 may be thinner than the thickness of the active material layer 42. Thereby, when the electrode 60 is laminated with the separation film, the insulating coating layer 44 and the separation film may be in weak contact with each other, or a gap may be formed between the insulating coating layer 44 and the separation film as compared with the degree of adhesion between the active material layer 42 of the electrode 60 and the separation film.

[0257] The insulating coating layer 44 provides a supporting force so that the base end portion of the plain portion is not deformed during the bending process of the divided segment 61. However, even if the supporting force is weaker than the bending force and is slightly deformed, since there is a slight gap between the insulating coating layer 44 and the separation film, the deformation of the insulating coating layer 44 does not immediately and directly affect the separation film.

[0258] The plurality of segment pieces 61 may form a plurality of segment piece groups from the core side toward the outer peripheral side. In the segment piece group, at least one of the lower inner angles between adjacent segment pieces in the winding direction, the axial height of the segment piece, the width of the segment piece in the winding direction, the shape of the segment piece, the height of the bottom of the cutting groove between two segment pieces, and the separation pitch between two segment pieces may be the same.

[0259] FIG. 7a shows an embodiment in which the widths, heights, and separation pitches of the segment pieces belonging to the same segment piece group are substantially the same.

[0260] Among the segment pieces belonging to different segment piece groups, at least one of the elements that were the same within the same group may be different.

[0261] In other forms, for the plurality of segment pieces, in group units or in two or more group units, the separation pitch may gradually or stepwise increase or vice versa from the core side toward the outer peripheral side.

[0262] In still other forms, for the plurality of segment pieces, in group units or in two or more group units, the separation pitch may gradually or stepwise increase from the core side toward the outer peripheral side and then gradually or stepwise decrease, or vice versa.

[0263] In still other forms, for the plurality of segment pieces, the gap between the bottom of the cutting groove 63 and the insulating coating layer 44 or the active material layer 42 may gradually or stepwise increase or vice versa from the core side toward the outer peripheral side.

[0264] In still other forms, for the plurality of segment pieces, the gap between the bottom of the cutting groove 63 and the insulating coating layer 44 or the active material layer 42 may gradually or stepwise increase or gradually or stepwise decrease. Or, vice versa.

[0265] In the embodiment of FIG. 7a, the height of each segment group is different. In the electrode assembly, the separation membrane SP can face the active material layer 42 and / or the insulating coating layer 44 of the electrode 60. Preferably, the end position of the separation membrane SP can be adjusted to improve the impregnation property of the electrolyte.

[0266] In the electrode assembly, a line extending parallel to the winding direction (X-axis) with reference to the lowest point among the first portion B1, the second portion B3, and the third portion B2 is defined as the reference line DL. When the segment having the lowest height among the plurality of segments is defined as the minimum segment, the end SL in the width direction of the separation membrane SP can be located in the outer direction of the electrode assembly within 30% of the height Ha of the minimum segment with reference to the reference line DL. Here, the outer direction of the electrode assembly means the direction from the active material layer 42 of the electrode 60 toward the plain portion 43.

[0267] Alternatively, the end SL in the width direction of the separation membrane SP can be located in the inner direction of the electrode assembly within 30% of the height Ha of the minimum segment with reference to the reference line DL. Here, the inner direction of the electrode assembly means the direction from the plain portion 43 of the electrode 60 toward the active material layer.

[0268] Preferably, the height Ha of the minimum segment can substantially correspond to the minimum value among the heights of the segments bent in the radial direction of the electrode assembly.

[0269] The reference line DL, which is a line extending parallel to the winding direction (X-axis) from the lowest point among the first portion B1, the second portion B3, and the third portion B2, corresponds to the bottom of the cutting groove 63 between adjacent segments, and the bottom of the cutting groove can be referred to as a notching valley.

[0270] According to an embodiment of the present invention, by controlling the end in the width direction of the separation membrane SP to be positioned close to the reference line DL, the electrolyte flows into the electrode assembly along the notch valley (empty space), so the impregnation rate increases. Specifically, when the electrolyte is injected into the battery housing in which the electrode assembly is inserted, the electrolyte moves to the notch valley between the sliced portions of the plain portion of the electrode. Then, the electrolyte is impregnated into the notch valley between the sliced portions, that is, the end of the separation membrane positioned close to the reference line, and finally impregnated into the active material layer of the electrode. As a result, the uniformity of electrolyte impregnation in the electrode assembly increases.

[0271] The more the end SL in the width direction of the separation membrane SP is positioned in the outer direction of the electrode assembly, the more negative the effect on the welding characteristics. Conversely, the more the end SL in the width direction of the separation membrane SP is positioned in the inner direction of the electrode assembly, the higher the risk of short circuit between the positive electrode and the negative electrode can be.

[0272] Therefore, in one aspect of the present invention, the end SL in the width direction of the separation membrane SP is controlled to be positioned in the outer direction of the electrode assembly within 30% of the height of the minimum sliced portion or in the inner direction of the electrode assembly within 30% of the height of the minimum sliced portion with reference to the reference line DL.

[0273] According to an embodiment of the present invention, the end SL in the width direction of the separation membrane SP can be positioned in the outer direction of the electrode assembly within 1.5 mm or in the inner direction of the electrode assembly within 1.5 mm with reference to the reference line DL.

[0274] Figure 7b is a diagram showing the definitions of the width D, height H, and separation pitch P of the trapezoidal sliced portion 61.

[0275] Referring to Figure 7b, the width D, height H, and separation pitch P of the sliced portion 61 are designed to prevent the plain portion 43 near the bending point from being broken during the bending process of the plain portion 43 and to prevent abnormal deformation of the plain portion 43 while sufficiently increasing the number of overlapping layers of the plain portion 43 to ensure sufficient welding strength.

[0276] The bending of the segment 61 is performed at line G passing through the bottom of the cutting groove 63 or above it. The cutting groove 63 enables smooth and easy bending of the segment 61 in the radial direction of the electrode assembly.

[0277] The width D of the segment 61 is defined as the length between two points where two straight lines extending from the side edges 63b on both sides of the segment 61 and a straight line extending from the bottom 63a of the cutting groove 63 intersect. The height H of the segment 61 is defined as the shortest distance between the uppermost edge of the segment 61 and a straight line extending from the bottom 63a of the cutting groove 63. The separation pitch P of the segments 61 is defined as the length between two points where a straight line extending from the bottom 63a of the cutting groove 63 and straight lines extending from two side edges 63b connected to the bottom 63a intersect. When the side edge 63b and / or the bottom 63a is a curve, the straight line can be replaced by a tangent line extending from the intersection point of the side edge 63b and the bottom 63a to the side edge 63b and / or the bottom 63a.

[0278] 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 side, the segments 61 may not overlap to ensure sufficient welding strength, or there may be a generated empty space (gap).

[0279] Preferably, the width D of the segment 61 can be adaptively adjusted according to the radius of the winding turn where the segment 61 is located so that the segments 61 can easily overlap in the radial direction when the segment 61 is bent toward the core side of the electrode assembly.

[0280] FIG. 7c is a view showing, with respect to the center O of the core of the electrode assembly, an arc A1A2 formed by the lower end of the segment 61 (line segment D in FIG. 7b) defining the width D of the segment 61 when the electrode 60 is wound according to an embodiment of the present invention. ab )

[0281] Referring to FIG. 7c, the arc A1A2 has a length corresponding to the width D of the segment 61 and has a circumferential angle Φ with respect to the center of the core of the electrode assembly. The circumferential angle Φ can be defined as the angle between two line segments connecting both ends of the arc A1A2 and the center O of the core on a plane perpendicular to the winding axis passing through the arc A1A2.

[0282] When the lengths of the arcs A1A2 of the segment 61 are the same, the circumferential angle Φ decreases as the radius r of the winding turn where the segment 61 is located increases. Conversely, when the circumferential angle Φ of the segment 61 is the same, the length of the arc A1A2 increases proportionally as the radius r of the winding turn where the segment 61 is located increases.

[0283] The circumferential angle Φ affects the bending quality of the segment 61. In the drawing, the solid-line arrow indicates the direction of the force applied to bend the segment 61, and the dotted-line arrow indicates the direction in which the segment 61 is bent. The bending direction is the direction toward the center O of the core.

[0284] The circumferential angle Φ of the segment 61 can be 45° or less, preferably 30° or less, depending on the radius r of the winding turn where the segment 61 is located, in order to improve the uniformity of bending and prevent the occurrence of cracks.

[0285] In one form, the circumferential angle Φ of the segment 61 can gradually or stepwise increase or decrease along the radial direction of the electrode assembly within the above numerical range. In another form, the circumferential angle Φ of the segment 61 can 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 still another form, the circumferential angle Φ of the segment 61 can be substantially the same along the radial direction of the electrode assembly within the above numerical range.

[0286] According to experiments, when the circumferential angle Φ of the segment 61 exceeds 45°, the bending pattern of the segment 61 becomes non-uniform. The difference in the forces applied to the central portion and the side portion of the segment 61 increases, and the pressing of the segment 61 in the circumferential direction becomes non-uniform. Also, if the pressing force is increased for the sake of bending uniformity, there is a risk of cracks occurring in the plain portion 43 near the cutting groove 63.

[0287] In one example, the circumferential angles Φ of the segments 61 included in the electrode 60 are substantially the same, and the width of the segment 61 can increase proportionally as the radius r of the winding turn where the segment 61 is located increases. Substantially the same means either completely the same or having a deviation of less than 5%.

[0288] For example, when the radius of the electrode assembly is 22 mm, the radius of the core is 4 mm, and the segment 61 is arranged from the winding turn located at the point with a radius of 7 mm, when the circumferential angle Φ of the segment 61 is constant at 28.6°, the width D of the segment 61 can increase proportionally according to the radius r of the winding turn where the segment 61 is located as shown in Table 1 below. That is, the width of the segment 61 can increase at substantially the same ratio by 0.5 mm each time the radius r of the winding turn increases by 1 mm.

[0289]

Table 1

[0290] Preferably, the width D(r) of the segment 61 located in the winding turn with a radius r based on the center O of the core of the electrode assembly can be determined within a range that satisfies the following mathematical formula 1.

[0291] [Mathematical formula 1] 1 ≦ D(r) ≦ (2 × π × r / 360°) × 45° Preferably, for each of the plurality of segments 61, as the radius r of the winding turn where the segment 61 is located increases based on the center of the core of the electrode assembly, the width D(r) in the winding direction can gradually or stepwise increase, or vice versa.

[0292] In other forms, for each of the plurality of segmented pieces 61, as the radius r of the winding turn in which the segmented piece 61 is located increases with respect to the center of the core of the electrode assembly, the width D(r) in the winding direction may gradually or stepwise increase within the range of 1 mm to 11 mm, or vice versa.

[0293] In still other forms, for each of the plurality of segmented pieces 61, as the radius r of the winding turn in which the segmented piece 61 is located increases with respect to the center of the core of the electrode assembly, the width D(r) in the winding direction may gradually or stepwise increase and then gradually or stepwise decrease, or vice versa.

[0294] In still other forms, for each of the plurality of segmented pieces 61, as the radius r of the winding turn in which the segmented piece 61 is located increases with respect to the center of the core of the electrode assembly, the width D(r) in the winding direction may gradually or stepwise increase within the range of 1 mm to 11 mm and then gradually or stepwise decrease, or vice versa.

[0295] In still other forms, as the radius r of the winding turn in which the segmented piece 61 is located increases, the ratio at which the width D(r) of the segmented piece 61 changes may be the same or different.

[0296] In still other forms, as the radius r of the winding turn in which the segmented piece 61 is located increases, the ratio at which the width D(r) of the segmented piece 61 changes within the range of 1 mm to 11 mm may be the same or different.

[0297] Further referring to FIG. 7b, the height H of the segmented piece 61 may be 2 mm or more. If D2 is less than 2 mm, when the segmented piece 61 is bent toward the core side, there is a possibility that the segmented pieces 61 may not overlap to ensure sufficient welding strength, or a void (gap) may occur.

[0298] The height H of the slit piece 61 can be determined by applying the condition that the core is not blocked when the slit piece 61 is bent toward the core side. Preferably, the height H of the slit piece 61 can be adjusted so that 90% or more of the diameter of the core is opened to the outside.

[0299] Preferably, the height H of the slit piece 61 can gradually increase from the core side to the outer peripheral side according to the radius of the winding turn where the slit piece 61 is located and the radius of the core.

[0300] In one example, if the height H of the slit piece 61 increases stepwise in N steps from h1 to h as the radius of the winding turn increases N up to, then for the k-th height h k (k is a natural number from 1 to N) of the slit piece 61, the starting radius r k of the winding turn including the slit piece 61 having the height h k , and the radius r c of the core, the heights h1 to h N of the slit piece 61 can be determined so that the following Equation 2 is satisfied.

[0301] [Equation 2] 2 mm ≤ h k ≤ r k - α × r c (preferably, α is 0.90 to 1) When the height h k of the slit piece 61 satisfies Equation 2, even if the slit piece 61 is bent toward the core side, 90% or more of the diameter of the core can be opened to the outside.

[0302] As an example, the overall winding turn radius of the electrode assembly is 22 mm, the height of the slit piece 61 starts from 3 mm, and the height of the slit piece 61 increases in order of 3 mm, 4 mm, 5 mm, 6 mm each time the radius of the winding turn including the slit piece 61 increases by 1 mm, and the height can be substantially maintained at 6 mm in the remaining winding turns. That is, among the overall winding turn radii, the radial width of the variable height section of the slit piece 61 is 3 mm, and the remaining radius section corresponds to the uniform height section.

[0303] In this case, the radius r cThe starting radii r1, r2, r3, r3 of the winding turns including the segmented slices 61 having heights of 3 mm, 4 mm, 5 mm, and 6 mm according to the following are as shown in Table 2 below when α is 1 and the equality condition is applied in the right - hand inequality.

[0304]

Table 2

[0305] When the segmented slice 61 is arranged at the radius positions shown in Table 2, even if the segmented slice 61 is bent toward the core side, the core is not blocked by the segmented slice 61. On the other hand, r1, r2, r3, r3 shown in Table 2 can be shifted toward the core side according to the α value. In one example, when α is 0.90, r1, r2, r3, r3 can be shifted toward the core side by 10% of the core radius. In this case, when the segmented slice 61 is bent toward the core side, 10% of the core radius is blocked by the segmented slice 61. r1, r2, r3, r3 shown in Table 2 are the limit values of the position where the segmented slice 61 starts. Therefore, the position of the segmented slice 61 can be shifted by a predetermined distance to the outer peripheral side from the radius shown in Table 2. FIG. 7d is a diagram schematically showing the relationship between the heights h1, h2, h3, h4 of the segmented slice 61, the core radius r c , and the radii r1, r2, r3, r3 of the winding turns at which the segmented slice 61 starts to appear.

[0306] Referring to Table 2 and FIG. 7d, for example, the radius r of the core C cWhen it is 3 m, the starting radii r1, r2, r3, and r3 of the winding turns including the segmented pieces 61 having heights of 3 mm (h1), 4 mm (h2), 5 mm (h3), and 6 mm (h4) can be 6 mm, 7 mm, 8 mm, and 9 mm respectively, and the height of the segmented piece 61 can be maintained at 6 mm from a radius of 9 mm to the last winding turn. Also, the winding turns having a radius smaller than 6 mm (r1) may not include the segmented piece 61. In such an example, since the segmented piece 61 with a height of 3 mm (h1) closest to the core C is located from the winding turn with a radius of 6 mm, even if the corresponding segmented piece 61 is bent toward the core C side, it only covers the radius interval of 3 mm to 6 mm and does not substantially block the core C. Depending on the α value in Equation 2, the position of the segmented piece 61 can be shifted toward the core C side within 10% of the core radius r c and can be shifted by within 10% of the core radius r toward the core C side.

[0307] In other forms, the height of the segmented piece 61 can increase at the same or different ratios as the starting radius r of the winding turn where the segmented piece 61 is located increases with reference to the center of the core of the electrode assembly.

[0308] Preferably, the height H of the segmented piece 61 satisfies Equation 2 and the maximum height of the segmented piece 61 can be limited.

[0309] FIG. 7e is a conceptual diagram for determining the maximum value h with respect to the height H of the segmented piece 61 in the variable height interval of the segmented piece 61. max and is a conceptual diagram for determining the maximum value h with respect to the height H of the segmented piece 61 in the variable height interval of the segmented piece 61.

[0310] Referring to FIG. 7e, in the winding structure of the electrode assembly, the electrode E1 including the segmented piece 61 faces the electrode E2 of the opposite polarity with the separation film S interposed therebetween in the radial direction. Active material layers E 1,active are coated on both sides of the electrode E1, and active material layers E 2,active are also coated on both sides of the electrode E2. For electrical insulation, the end S end of the separation film S is insulated from the end E 2,end of the electrode E2 by an insulating gap W gapIt can further extend outward by a length corresponding thereto. Also, the end of the electrode E1 does not extend outside the end of the electrode E2 for electrical insulation. Therefore, an insulating gap W gap corresponding section must be ensured at the lower end of the plain portion 43. Also, when the electrodes E1, E2 and the separation membrane S are wound, the end S end of the separation membrane S meanders. Therefore, in order for the segment 61 to be exposed outside the separation membrane S, the section W margin,min corresponding to the minimum meandering margin of the separation membrane S must be allocated to the plain portion 43. Also, in order to cut the segment 61, a minimum cutting scrap margin W scrap,min must be allocated to the end of the current collector foil. Therefore, the maximum height h max of the segment 61 in the height variable section of the segment 61 can be determined by the following Equation 3. In Equation 3, W foil corresponds to the width of the current collector foil before the current collector foil is cut.

[0311] [Equation 3] h max =W foil -W scrap,min -W margin,min -W gap Preferably, the insulating gap W gap can be 0.2 mm to 6 mm when the first electrode is the positive electrode. Also, the insulating gap W gap can be 0.1 mm to 2 mm when the first electrode is the negative electrode.

[0312] Preferably, the minimum cutting scrap margin W scrap,min can be 1.5 mm to 8 mm. The minimum cutting scrap margin W scrap,min may not be allocated depending on the process of forming the segment 61. For example, a cutting groove 63 can be formed such that the upper side of the segment 61 coincides with the upper side of the current collector foil. In this case, in Equation 3, W scrap,min can be 0.

[0313] Preferably, the minimum meandering margin W of the separation membrane margin,min can be 0 to 1 mm.

[0314] As an example, the minimum cutting scrap margin W scrap,min is 1.5 mm, and the minimum meandering margin W of the separation membrane S margin,min can be 0.5 mm. Under such conditions, the current collector foil width W foil before forming the segment 61 is 8 mm to 12 mm, and when the insulation gap W gap is 0.6 mm, 0.8 mm, and 1.0 mm, the maximum height h of the segment 61 is calculated using Equation 3 max and the results are as shown in Table 3 below.

[0315]

Table 3

[0316] Referring to Table 3, the maximum height h of the segment 61 max in the height variable range of the segment 61 can be set to 10 mm. Therefore, the height of the segment 61 in the height variable range of the segment 61 satisfies Equation 2 and can increase stepwise or gradually along the radial direction of the electrode assembly in the range of 2 mm to 10 mm. Design conditions where the height of the segment 61 exceeds 10 mm may cause undulations in the non-patterned portion and reduce the flatness of the non-patterned portion. Further referring to FIG. 7b, the separation pitch P of the segment 61 can be adjusted in the range of 0.05 to 1.0 mm. If the separation pitch P is less than 0.05 mm, when the electrode 60 travels during a winding process or the like, cracks may occur in the non-patterned portion 43 near the bottom of the cutting groove 63 due to stress. On the other hand, if the separation pitch P exceeds 1 mm, when the segment 61 is bent, there is a possibility that the segment 61 may not overlap to ensure sufficient welding strength, or an empty space (gap) may be generated.

[0317] On the other hand, when the current collector 41 of the electrode 60 is made of aluminum, it is more preferable to set the separation pitch P to 0.5 mm or more. When the separation pitch P is 0.5 mm or more, even if the electrode 60 travels at a speed of 100 mm / sec or more under a tension of 300 gf or more in a winding process or the like, it is possible to prevent cracks from occurring at the lower part of the cutting groove 63.

[0318] According to the experimental results, when the current collector 41 of the electrode 60 is an aluminum foil with a thickness of 15 μm and the separation pitch P is 0.5 mm or more, no cracks occur at the lower part of the cutting groove 63 when the electrode 60 travels under the above running conditions.

[0319] As shown in Fig. 7b, a cutting groove 63 is interposed between two adjacent segments 61 in the winding direction (X axis). The cutting groove 63 corresponds to the space generated while the plain part 43 is removed. Preferably, the corner portions at both ends of the bottom of the cutting groove 63 are rounded. 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 and the side 63b of the segment 61. In a modified example, the bottom 63a of the cutting groove 63 may be replaced with an arc shape. In this case, the sides 63b of the segment 61 can be smoothly connected by the arc shape of the bottom 63a.

[0320] The radius of curvature of the rounded portion 63c can be more than 0 and 0.5 mm or less, preferably more than 0 and 0.1 mm or less, and more preferably 0.01 mm to 0.05 mm. When the radius of curvature of the rounded portion 63c satisfies the above numerical range, it is possible to prevent cracks from occurring at the lower part of the cutting groove 63 when the electrode 60 travels during a winding process or the like. If the radius of curvature of the rounded portion 63c exceeds the upper limit of the above numerical range, the space at the bottom of the cutting groove 63 may decrease, which may have an adverse effect on the impregnation property of the electrolyte.

[0321] The plurality of segment pieces 61 may have an increasing lower inner angle θ from the core side toward the outer peripheral side. As an example, the plurality of segment pieces 61 may have a gradually or stepwise increasing lower inner angle θ from the core side toward the outer peripheral side. The lower inner angle θ is an angle between a straight line extending from the bottom 63a of the cutting groove 63 and a straight line extending from the side portion 53b of the segment piece 61. When the segment piece 61 is symmetric about the left and right, the lower inner angles θ on the left and right sides are substantially the same.

[0322] If the radius of the electrode assembly increases, the radius of curvature increases. If the lower inner angle θ of the segment piece 61 increases as the radius of the electrode assembly increases, when the segment piece 61 is bent, the stress generated in the radial direction and the circumferential direction can be relaxed. Further, if the lower inner angle θ increases, when the segment piece 61 is bent, both the area overlapping with the inner segment piece 61 and the number of overlapping layers increase, so that the welding strength can be ensured uniformly in the radial direction and the circumferential direction, and the bent surface region can be formed flat.

[0323] Preferably, the lower inner angle θ can be determined by the radius of the winding turn where the segment piece 61 is located and the width D of the segment piece 61.

[0324] FIG. 7f is a schematic diagram for explaining a mathematical formula for determining the lower inner angle θ of the segment piece 61.

[0325] Referring to FIG. 7f, it is ideal that the sides of the segment piece 61 coincide with the line segments AE and DE that connect the center E of the core with A and D, which are the two ends of the line segment AD corresponding to the width D of the segment piece 61.

[0326] When the sides of the segment piece 61 extend in the most ideal direction, the lower inner angle θ of the segment piece 61 refer can be approximately determined from the width D of the segment piece 61 and the radius r of the winding turn where the segment piece 61 is located using the following mathematical formula 4, assuming that the line segment EF is approximately equal to the line segments AE and DE.

[0327] [Mathematical formula 4]

[0328] [Number]

[0329] The angle in Equation 4 is the lower interior angle θ of the segment 61 refer is an ideal reference angle. Meanwhile, there is a separation pitch P between adjacent segment pieces 61 located on the same winding turn. The length of the separation pitch P is indicated as p. Since the separation pitch P exists between adjacent segment pieces 61, a tolerance of only 50% of the separation pitch P can be given to the lower interior angle θ. In other words, the width of the upper end side BC of the segment piece 61 can increase by a maximum of p / 2 to the upper end side B'C'. The lower interior angle θ' reflecting the tolerance can be expressed by the following Equation 5. Lower interior angle θ refer is the ideal reference angle ∠BAG, and the lower interior angle θ' is the angle ∠B'AG' reflecting the tolerance due to the separation pitch P. In Equation 5, H is the height of the component segment 61, and p corresponds to the separation pitch.

[0330] [Formula 5]

[0331]

number

[0332] Preferably, the lower interior angle θ of the segment 61 located at each winding turn of the electrode assembly may satisfy the following formula 6. As a result, when the segment 61 is bent toward the center of the core of the electrode assembly, the segment 61 adjacent to each other in the circumferential direction do not interfere with each other, and the segment 61 can be bent smoothly.

[0333] [Formula 6]

[0334]

number

[0335] 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 interior angle of the segment 61 may increase gradually or stepwise in the range of 60° to 85° in the height variable section.

[0336] As another example, the plurality of segments 61 may have the lower inner angle θ gradually or stepwise increasing from the core side toward the outer peripheral side in one or two or more group units.

[0337] On the other hand, the lower left inner angle and the lower right inner angle of the segment 61 may not be equal. Still, at least one of the lower inner angles θ can be designed to satisfy the above-described formula 6.

[0338] Referring further to FIG. 7a, the width d of the first portion B1 B1 is designed such that when the segment 61 of the third portion B2 is bent toward the core side, the core of the electrode assembly is opened outward by 90% or more based on its diameter. The width d of the first portion B1 B1 can increase in proportion to the bending length of the segment 61 of group 1. The bending length corresponds to the length from the bending point to the upper end side of the segment 61. Preferably, when the electrode 60 is used to manufacture an electrode assembly of a cylindrical battery with a form factor 4680, the width d of the first portion B1 B1 can be set to 180 mm to 350 mm according to the diameter of the core of the electrode assembly and the height of the segment 61 included in group 1.

[0339] The bending point of the segment 61 can be set at a line passing through the bottom of the cutting groove 63 or a point separated from that line by a predetermined distance upward. If the segment 61 is bent toward the core side at a point separated from the bottom of the cutting groove 63 by a predetermined distance, the overlapping of the segments in the radial direction becomes easier. When the segment 61 is bent, the segment on the outer side presses the segment on the inner side with respect to the center of the core. At this time, if the bending point is separated from the bottom of the cutting groove 63 by a predetermined distance, the overlapping of the segments is more easily performed while the inner segment is pressed in the winding axis direction by the outer segment. The separation distance of the bending point can preferably be 1 mm or less. Since the minimum height of the segment is 2 mm, the ratio of the separation distance of the bending point to the minimum height can be 50% or less.

[0340] In one example, the width of each group of divided sections can be designed to constitute the same winding turn of the electrode assembly. Here, the winding turn can be counted based on the end of the first portion B1 in a state where the electrode 60 is wound.

[0341] In other variations, the width of each group of divided sections can be designed to constitute at least one winding turn of the electrode assembly.

[0342] In yet another variation, the width and / or height and / or separation pitch of the divided sections 61 belonging to the same group of divided sections can increase or decrease gradually and / or stepwise and / or irregularly within the group or between adjacent groups.

[0343] Groups 1 to 8 are merely an example of the groups of divided sections included in the third portion B2. The number of groups, the number of divided sections 61 included in each group, and the width of the groups can be preferably adjusted so that the divided sections 61 overlap multiplicatively to maximize the dispersion of stress during the bending process of the plain portion 43 and sufficiently ensure the welding strength with the current collector.

[0344] In other variations, the height of the second portion B3 can decrease gradually or stepwise as in the first and second embodiments.

[0345] In yet another variation, the divided structure of the third portion B2 can be extended to the second portion B3 (see the dotted line). In this case, the second portion B3 can also include a plurality of divided sections, similar to the third portion B2. Preferably, the divided structure of the second portion B3 can be substantially the same as the outermost group of divided sections of the third portion B2. In this case, the divided sections included in the second portion B3 and the third portion B2 can have substantially the same width, height, and separation pitch. As a variation, the divided sections of the second portion B3 can have a width and / or height and / or separation pitch larger than that of the third portion B2. Optionally, the final one winding turn of the second portion B3 can be in a form where the divided sections are removed.

[0346] In the third part B2, with respect to the winding direction of the electrode 60, the section where the height of the segment 61 increases stepwise (groups 1 to 7) is defined as the variable height section of the segment, and the last segment group (group 8) can be defined as the uniform height section where the height of the segment is maintained uniformly.

[0347] That is, in the third part B2, when the height of the segment 61 increases stepwise from h1 to h N up to, the section where the segments 61 with a height of h1 to h N-1 (N is a high index and a natural number of 2 or more) corresponds to the variable height section, and the section where the segments 61 with a height of h N corresponds to the uniform height section. The ratio of the variable height section to the uniform height section with respect to the length of the electrode 60 in the winding direction will be described later with reference to specific embodiments.

[0348] When the electrode 60 is used to manufacture the electrode assembly of a cylindrical battery with a form factor of 4680, the width d B1 of the first part 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 B3 of the second part B3 can be 180 to 350 mm, similar to the width of the first part B1.

[0349] In an embodiment, the widths of Group 1 to Group 8 do not show a constant increase or decrease pattern. The reason is that although the width of the segmented piece gradually increases from Group 1 to Group 8, the number of segmented pieces included in each group is limited to an integer, and the thickness of the electrode has a slight deviation in the winding direction. Therefore, in a specific segmented piece group, the number of segmented pieces can decrease. Accordingly, the width of the group can show an irregular change pattern as exemplified above from the core side to the outer peripheral side. Of course, by decreasing the width of the segmented piece, it is also possible to design such that the widths of Group 1 to Group 8 show a constant increase pattern.

[0350] That is, in the circumferential direction of the electrode assembly, when the widths in the winding direction for each of three continuously adjacent segmented piece groups are W1, W2, and W3 respectively, it may include a combination of segmented piece groups in which W3 / W2 is smaller than W2 / W1.

[0351] In the specific example described above, Groups 4 to 6 correspond to the above case. The width ratio of Group 5 to Group 4 is 120 to 130%, and the width ratio of Group 6 to Group 5 is 100 to 120%, and the value is smaller than 120 to 130%.

[0352] According to still another modification, when the non-patterned portion 43 of the electrode 60 has a plurality of segmented piece groups, the segmented piece groups G k-1 , G k , G k+1 may be arranged to be spaced apart from each other in the winding direction (X-axis) with an inter-group spacing Db interposed therebetween, as shown in FIG. 7g. The height of the non-patterned portion corresponding to the inter-group spacing Db may be substantially the same as the first portion B1 or the second portion B3.

[0353] In one form, from the core side to the outer peripheral side, the width D in the winding direction of the segmented piece 61 belonging to each segmented piece group increases stepwise for each group, the height H of the segmented piece 61 also increases stepwise for each group, and the lower inner angle θ may also increase stepwise for each group.

[0354] In other forms, the width Dg in the winding direction of the segment group may gradually or stepwise increase from the core side toward the outer peripheral side. The width Dg in the winding direction may increase for each segment group or may increase for every two or more segment groups.

[0355] In still other forms, the interval (group separation interval Db) between segment groups may gradually or stepwise increase from the core side toward the outer peripheral side. The group separation interval Db may increase for each segment group or may increase for every two or more segment groups.

[0356] When the width Dg in the winding direction of the segment group and the group separation interval Db are adjusted, as shown in FIGS. 7h and 7i, the segments 61 are radially arranged in a partial region to form one or more segment alignment portions 61g. The segment alignment portion 61g is an assembly of segment groups G k-1 , G k , G k+1 aligned along the radial direction of the electrode assembly JR.

[0357] As shown in FIG. 7j, when the two side ends of the segment groups G k-1 , G k , G k+1 included in the segment alignment portion 61g and the center O of the core C are connected by a line, it becomes a sector shape for each segment group.

[0358] Preferably, the sector shapes of the segment groups G k-1 , G k , G k+1 included in the segment alignment portion 61g may have substantially the same circumferential angle δ and range of the circumferential angle δ. If there is a thickness tolerance in the electrode, the sector shapes of the segment groups G k-1 , G k , G k+1 included in the segment alignment portion 61g may have substantially the same circumferential angle δ, and the ranges of the circumferential angle δ may be different.

[0359] The circumferential angle δ can be 20° or more, optionally 25° or more, optionally 30° or more, optionally 35° or more, or optionally 40° or more.

[0360] When the segment 61 included in the segment alignment portion 61g is bent around the core C, as shown in FIGS. 7h and 7i, a bending surface region F is formed on a plane substantially perpendicular to the winding axis. Further, an electrolyte impregnation portion Ep is formed between adjacent bending surface regions F in the circumferential direction.

[0361] Since the bending structure of the segment 61 does not exist in the electrolyte impregnation portion Ep, the end portion of the separation membrane and the active material layer of the electrode are exposed to the outside when viewed from the winding axis direction (i.e., the direction in which the electrolyte is injected). Therefore, when the electrolyte is injected from the winding axis direction of the electrode assembly JR, the electrolyte quickly penetrates into the electrode assembly JR while directly contacting the end portions of the separation membrane and the active material layer, so that the impregnation rate of the electrolyte can be improved.

[0362] Also, as described above with reference to FIG. 7a, in order to further improve the impregnation rate of the electrolyte, it is preferable that the end SL in the width direction of the separation membrane SP is separated from the reference line DL by a distance corresponding to 30% or less of the height Ha of the minimum segment. In this case, since the electrolyte is impregnated through the bottom of the cutting groove 63, the impregnation rate of the electrolyte can be further improved and the uniformity of the electrolyte impregnation can also be improved.

[0363] FIG. 7h is an illustration of a structure in which the bending surface regions F are arranged at 90° intervals, and FIG. 7i is an illustration of a structure in which the bending surface regions F are arranged at 180° intervals. Here, the arrangement angle of the bending surface region F can be defined as the angle between straight lines passing through the geometric centers of figures approximately corresponding to the peripheral shapes of the bending surface regions F. That is, when a line connecting the center of the core of the electrode assembly and the geometric center of a figure approximately corresponding to the bending surface region F is defined as an angle measurement line, the angle measured using the angle measurement lines of adjacent bending surface regions F in the circumferential direction can be regarded as the arrangement angle of the bending surface region F. As an example, the geometric center of the figure corresponding to the periphery of the bending surface region F can be the centroid.

[0364] The segmented group that constitutes the bent surface region F can be arranged radially from the center of the core of the electrode assembly JR. Also, the plain part of the winding turn portion that constitutes the electrolyte impregnated portion Ep can be arranged radially from the center of the core of the electrode assembly JR. The circumferential length of the segmented group included in the bent surface region F can gradually increase from the core toward the outer peripheral side. And the plain part of the winding turn portion that constitutes the electrolyte impregnated portion Ep also increases in circumferential length from the core toward the outer peripheral side. The figure formed by the periphery of the bent surface region F is a shape similar to a sector with the central part removed generally.

[0365] The electrode assembly JR shown in FIG. 7h is suitable for welding a current collector in which four welding regions are designed radially at 90° intervals, and the electrode assembly JR shown in FIG. 7i is suitable for welding a current collector in which two welding regions are designed radially at 180° intervals.

[0366] In the embodiment, a structure in which four bent surface regions F (welding regions) exist at 90° intervals or two bent surface regions F exist at 180° intervals is exemplified, but the present invention is not limited thereto. For example, various radial arrangements are possible, such as arranging 12 bent surface regions at 30° intervals, 8 bent surface regions at 45° intervals, 6 bent surface regions at 60° intervals, 5 bent surface regions at 72° intervals, and 3 bent surface regions at 120° intervals.

[0367] In other modifications, the bent surface region F may not be arranged radially and may be formed in various patterns at positions corresponding to the regions where the current collector is welded. The bent surface region F can be in the form of geometric figures such as a square, a rectangle, a parallelogram, or a trapezoid. Such various shapes of the bent surface region F can be determined by adjusting the width Dg in the winding direction of the segmented group and the separation interval Db between the segmented groups.

[0368] On the one hand, when the segmented slice groups are arranged at intervals along the winding direction (X-axis) so that the bent surface region F is not formed in a partial region, due to the thickness tolerance of the electrodes, displacement of the segmented slice groups may occur from the core toward the outer peripheral side. Such displacement of the segmented slice groups accumulates as the outer peripheral turns are made.

[0369] According to an embodiment of the present invention, even if the displacement of the segmented slice groups accumulates as the outer peripheral turns are made, in order to secure a region where the current collector can be welded, the width of the segmented slice groups gradually or stepwise increases from the core toward the outer peripheral side, and as a result, a bent surface region F in the shape of a sector is formed.

[0370] Therefore, even if the displacement of the segmented slice groups accumulates more and more toward the outer peripheral side and the shape of the bent surface region F is deformed (referring to FIG. 7i, the shape of the bent surface region F is also deformed clockwise as the electrode assembly is wound clockwise), as can be confirmed in the deformed region indicated by the arrow in FIG. 7i, a predetermined welding region w can still be sufficiently secured.

[0371] The circumferential angle of the sector shape (refer to δ in FIG. 7j) in which the bent surface region F is formed can be determined by the amount of accumulated displacement. In the embodiment, a sector shape having a circumferential angle of about 30° is exemplified. The larger the circumferential angle of the sector shape, the greater the accumulated amount of allowable displacement. On the other hand, the area of the electrolyte impregnated portion Ep where the bent surface region F is not formed tends to decrease.

[0372] On the other hand, when the region corresponding to the width of the segmented slice groups consists of one segmented slice, the larger the circumferential angle of the sector shape corresponding to the bent surface region F, the more deformation occurs in the circumferential direction when the segmented slice is bent, and smooth bending becomes impossible. Therefore, in an embodiment of the present invention, when designing the bent surface region F in a sector shape, a plain portion section of the winding turn region corresponding to the sector shape is formed by the segmented slice groups, and each segmented slice belonging to the corresponding group is bent so that the bending process of the plain portion is performed smoothly.

[0373] According to the embodiment, when the circumferential angle of the winding turn portion located within the sector corresponding to the bent surface region F exceeds 30°, the plain portion of the winding turn portion is divided into at least two segments, and the circumferential angle of the winding turn portion corresponding to each segment is set to be 30° or less.

[0374] In one embodiment of the present invention, the shape of the segment 61 can be deformed in various ways.

[0375] FIG. 8a is a plan view showing the structure of the electrode 70 according to the fifth embodiment of the present invention.

[0376] Referring to FIG. 8a, the electrode 70 of the fifth embodiment has substantially the same configuration as that of the above-described embodiment except that the shape of the segment 61' is different. Therefore, unless otherwise specified, the configuration of the fourth embodiment can be similarly applied to the fifth embodiment.

[0377] The segment 61' has a form of a geometric figure in which the upper width and the lower width are substantially the same. Preferably, the segment 61' can be square-shaped.

[0378] The corners of the square shape, i.e., the vertex portions, are not sharp ends but can be rounded or chamfered like a chamfering process.

[0379] FIG. 8b is a diagram showing the definition of the width, height, and separation pitch of the square segment 61'.

[0380] Referring to FIG. 8b, the width D, height H, and separation pitch P of the segment 61' are set so as to sufficiently increase the number of overlapping layers of the plain portion 43 and prevent abnormal deformation of the plain portion 43 in order to prevent the plain portion 43 from being torn during the bending process of the plain portion 43 and improve the welding strength with the current collector. Abnormal deformation means that the plain portion below the bending point cannot maintain a straight state and collapses and is deformed irregularly.

[0381] The width D of the segment 61’ is defined as the length between two points where two straight lines extending from the side edges on both sides of the segment 61’ intersect with a straight line extending from the bottom 63a of the cutting groove 63. The height H of the segment 61’ is defined as the shortest distance between the uppermost edge of the segment 61’ and a straight line extending from the bottom 63a of the cutting groove 63. The separation pitch P of the segment 61’ is defined as the length between two points where a straight line extending from the bottom 63a of the cutting groove 63 intersects with two straight lines extending from the two side edges 63b connected to the bottom 63a. When the side edge 63b and / or the bottom 63a is curved, the straight line can be replaced by a tangent line extending from the intersection of the side edge 63b and the bottom 63a to the side edge 63b and / or the bottom 63a.

[0382] Preferably, the conditions regarding 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 square-shaped, the lower inner angle of the segment 61’ can be a constant 90°.

[0383] Also, the electrode 70 according to the fifth embodiment can also be arranged in the winding direction (X-axis) with a plurality of segment groups G k-1 , G k , G k+1 intervening with a separation interval Db. In this case, the embodiments described above with reference to FIGS. 7h, 7i, and 7j can also be substantially applied to the electrode assembly manufactured by winding the electrode 70 shown in FIG. 8c. That is, the only difference is that the shape of the segments included in the segment group is changed from trapezoidal to square, and other features can be substantially applied in the same way as the embodiments described with reference to FIGS. 7h, 7i, and 7j.

[0384] When the third part B2 and the second part B3 include a plurality of segments 61, 61’ as in the fourth and fifth embodiments, the shape of each segment 61, 61’ can be variously deformed.

[0385] Preferably, the segments can be deformed in various forms while satisfying at least one of the following conditions.

[0386] Condition 1: The width of the lower part is wider than the width of the upper part.

[0387] Condition 2: The width of the lower part is equal to the width of the upper part.

[0388] Condition 3: The width is maintained the same from the lower part to the upper part.

[0389] Condition 4: The width decreases from the lower part to the upper part.

[0390] Condition 5: The width decreases from the lower part to the upper part and then increases.

[0391] Condition 6: The width increases from the lower part to the upper part and then decreases.

[0392] Condition 7: The width increases from the lower part to the upper part and then is maintained constant.

[0393] Condition 8: The width decreases from the lower part to the upper part and then is maintained constant.

[0394] Condition 9: One inner angle on one side of the lower part is the same as the other inner angle on the other side.

[0395] Here, the inner 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. When the side is a curve, the inner 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.

[0396] Condition 10: One inner angle on one side of the lower part is different from the other inner angle on the other side.

[0397] Condition 11: One inner angle on one side of the lower part and the other inner angle on the other side of the lower part each have an acute angle, a right angle, or an obtuse angle.

[0398] Condition 12: It is symmetric about the winding axis direction.

[0399] Condition 13: It is asymmetric about the winding axis direction.

[0400] Condition 14: The side is linear.

[0401] Condition 15: The side is curved.

[0402] Condition 16: The side is convex outward.

[0403] Condition 17: The side is convex inward.

[0404] Condition 18: The upper and / or lower corners have a structure where a straight line intersects with another straight line.

[0405] Condition 19: The upper and / or lower corners have a structure where a straight line intersects with a curve.

[0406] Condition 20: The upper and / or lower corners have a structure where a curve intersects with another curve.

[0407] Condition 21: The upper and / or lower corners have a round structure.

[0408] FIG. 9 is a diagram exemplarily showing the form of a segmented piece according to a modified form of the present invention.

[0409] As shown in the drawing, the segmented piece may have the form of various geometric figures with a dotted line connecting the bottoms of the cutting grooves on both sides as the base. The geometric figure has a structure in which at least one straight line, at least one curve, or a combination thereof is connected. As an example, the segmented piece may have a polygonal shape, a round pattern, or various forms in which these are combined.

[0410] Specifically, the segmented piece may be a trapezoid with left-right symmetry (circle a); a trapezoid with non-left-right symmetry (circle b); a parallelogram shape (circle c); a triangle shape (circle l); a pentagon shape (circle k); an arc shape (circle e); or an ellipse shape (circle f).

[0411] The form of the segmented piece is not limited to that shown in FIG. 9, and may be deformed into other polygonal shapes, other round shapes, or combinations thereof so as to satisfy at least one of the above-described Conditions 1 to 21.

[0412] In the polygonal round shapes a, b, c, k, and l of the segments, the upper corners and / or the lower corners can be in the shape where straight lines intersect or in a round shape (refer to the enlargement of the upper corner and the lower corner of round shape a).

[0413] In the polygonal round shapes a, b, c, k, and l of the segments and the round shapes e and f of the segments, the lower one-side interior angle θ1 and the other-side interior angle θ2 can be the same or different, and the lower one-side interior angle θ1 and the other-side interior angle θ2 can be acute, right, or obtuse angles respectively. The interior angle is the angle formed by the base and the side of a geometric figure. When the side is a curve, the straight line can be replaced by a tangent line extending from the intersection point of the base and the side.

[0414] The shape of the side of the polygonal segment can be deformed in various ways.

[0415] As an example, the side of the segment in the form of round shape a can be deformed into a curve bulging outward like round shape d, or into a curve concave inward inside the segment like round shape g or j.

[0416] As another example, the side of the segment in the form of round shape a can be deformed into a broken line concave inward inside the segment like round shape h or i. Although not shown, the side of the segment in the form of round shape a can be deformed into a broken line bulging outward.

[0417] In the segments in the form of round shapes d, g, j, h, and i where the sides are deformed in various ways, the lower one-side interior angle θ1 and the other-side interior angle θ2 are the same or different, and the lower one-side interior angle θ1 and the other-side interior angle θ2 can be acute, right, or obtuse angles respectively.

[0418] The width of the segment can have various change patterns from the lower part to the upper part.

[0419] As an example, the width of the segmented slice can be maintained constant from the lower part to the upper part (Form round c). As another example, the width of the segmented slice can gradually decrease from the lower part to the upper part (Forms round a, round b, round d, round e, round f, and round g). As yet another example, the width of the segmented slice 61 can gradually decrease from the lower part to the upper part and then increase (Forms round i and round j). As yet another example, the width of the segmented slice can gradually increase from the lower part to the upper part and then decrease (Form round k). As yet another example, the width of the segmented slice can gradually decrease from the lower part to the upper part and then be maintained constant (Form round h). Although not shown, the width of the segmented slice can gradually increase from the lower part to the upper part and then be maintained constant.

[0420] On the other hand, among the forms of the segmented slices illustrated in FIG. 9, the upper flat polygonal shape can be rotated 180°. As an example, when Form round a, round b, round d, or round g of the segmented slice is rotated 180°, the width of the segmented slice can gradually increase from the lower part to the upper part. As another example, when Form round h of the segmented slice is rotated 180°, the width of the segmented slice can be maintained constant from the lower part to the upper part and then gradually increase.

[0421] In the above-described embodiments (deformed forms), according to another form of the present invention, it is also possible to change the shapes of the segmented slices 61 and 61' along the region of the third part B2. As an example, a round shape (e.g., semi-circular, semi-elliptical, etc.) advantageous for stress dispersion can be applied to the section where stress is concentrated, and a polygonal shape with the largest possible area (e.g., quadrilateral, trapezoid, parallelogram, etc.) can be applied to the section where stress is relatively low.

[0422] In yet another form, the plurality of segmented slices can have different forms individually, in group units, or in two or more group units along a direction parallel to the winding direction of the electrode assembly.

[0423] In the above-described embodiments (modifications), the slitting structure of the third portion B2 can also be applied to the first portion B1. However, if the slitting structure is applied to the first portion B1, depending on the curvature radius of the core, when the slit pieces 61, 61' of the third portion B2 are bent, there may be a reverse forming phenomenon in which the end of the first portion B1 bends to the outer peripheral side. Therefore, it is preferable not to apply the slitting structure to the first portion B1, or, even if the slitting structure is applied, to consider the curvature radius of the core and adjust the width and / or height and / or separation pitch of the slit pieces 61, 61' to a level at which reverse forming does not occur.

[0424] The height of the slit piece where reverse forming may occur can be less than about 3 mm. Also, if the height of the slit piece is less than 2 mm, the slit piece and the separation film may interfere with each other and it may become difficult to bend. Furthermore, if the height of the slit piece is less than 4 mm, there is a possibility that the welding process of the slit piece may not be performed smoothly. Preferably, the minimum height H of the slit piece designed for bending min can be 5 mm.

[0425] Referring to FIGS. 8a and 9a, with reference to the reference line DL, the minimum height H that can be bent in the plain portion min (for example, 2 mm, 3 mm, 4 mm or 5 mm described above) or more, if the end SL in the width direction of the separation film exists within the range of ±30% of the minimum height Ha of the minimum slit piece, the impregnation property can be significantly improved. That is, when determining the minimum slit piece that defines the position of the end SL in the width direction of the separation film, slit pieces that may cause reverse forming or slit pieces that are not bent can be excluded.

[0426] Explaining from another perspective, with reference to the reference line DL, if the end SL in the width direction of the separation film exists within the range of ±30% of the larger height {max(Ha, H min )} of the minimum height Ha of the minimum slit piece existing in the plain portion and the minimum height H that can be bent min , the impregnation property can be significantly improved.

[0427] Explaining from another perspective, with reference to the reference line DL, the minimum foldable height H min If the end SL in the width direction of the separator film exists within the range of ±30% of min , the impregnation property of the electrolyte can be significantly enhanced. This can be in the range of reference line DL ±1.5 mm, reference line DL ±1.2 mm, reference line DL ±0.9 mm, or reference line DL ±0.6 mm.

[0428] Moreover, according to yet another aspect of the present invention, after the electrodes 60 and 70 are wound as an electrode assembly, the cut pieces exposed on the upper and lower sides of the electrode assembly can form a folded surface region while overlapping multiple times along the radial direction of the electrode assembly.

[0429] It is clarified in advance that the following description of the folded surface region can be substantially similarly applied to the folded surface region formed while the cut pieces in the cut piece alignment portion are folded.

[0430] FIG. 10a is a schematic diagram showing a cross-section of the folded surface region F formed while the cut piece 61 is folded toward the core C side of the electrode assembly 80. In FIG. 10a, only the left side of the cross-section of the folded surface region F is shown with reference to the winding axis of the electrode assembly 80. The folded surface region F can be formed on both the upper and lower portions of the electrode assembly 80. FIG. 10b is a perspective view schematically showing the electrode assembly 80 on which the folded surface region F is formed.

[0431] Referring to FIGS. 10a and 10b, the folded surface region F has a structure in which the cut piece 61 overlaps in a plurality of layers in the winding axis direction. The overlapping direction is the winding axis direction (Y-axis). Section circle 1 is a cut piece omission section (first part B1) without a cut piece, and section circles 2 and 3 are sections where the winding turns including the cut piece are located. Section circle 2 is a height variable section where the height of the cut piece 61 changes, and section circle 3 is a height uniform section where the height of the cut piece is maintained uniformly up to the outer periphery of the electrode assembly. As will be described later, the radial lengths of section circle 2 and section circle 3 can vary. On the other hand, at least one winding turn including the outermost winding turn may not include a cut piece structure. In this case, section circle 3 to the second part B3 can be excluded.

[0432] In section circle 2, the height of the segment 61 is from the radius r1 to r of the electrode assembly 80 N in the section where the minimum height h1 (= h min ) to the maximum height h N (= h max ) can change step by step. The height variable section where the height of the segment 61 changes is r1 to r N . From the radius r N to the radius R of the electrode assembly 80, the height of the segment 61 is maintained uniformly at h N . That the height is uniform means that the deviation of the height is within 5%.

[0433] At any radius position in section circle 2 and section circle 3, the number of layers of the segment 61 changes depending on the radius position. Also, the number of layers of the segment 61 can change depending on the width of section circle 2, the minimum height h1 and the maximum height h of the segment in the height variable section of the segment 61 N , and the amount of change Δh in the height of the segment 61. The number of layers of the segment 61 is the number of segments that intersect the virtual line when a virtual line is drawn in the winding axis direction from any radius position of the electrode assembly 80

[0434] Preferably, by adjusting the height, width and separation pitch of the segment 61 according to the radius of the winding turn including the segment 61, the number of layers of the segment 61 at each position in the bent surface region F can be optimized according to the required welding strength of the current collector

[0435] First, when the minimum height h1 of the segment is the same in the height variable section (circle 2) of the segment 61, how the number of layers of the segment 61 changes along the radial direction of the bent surface region F due to the change in the maximum height h of the segment 61 N will be described with specific examples

[0436] Electrode assemblies of Examples 1-1 to 1-7 were prepared. The electrode assembly of the example had a radius of 22 mm and a core diameter of 4 mm. The positive electrode and the negative electrode included in the electrode assembly had the electrode structure shown in FIG. 7a. That is, the form of the segmented piece was trapezoidal. The second part B3 of the positive electrode and the negative electrode did not include the segmented piece. The length of the second part B3 was 3% to 4% of the total length of the electrode. The positive electrode, the negative electrode, and the separator were wound by the method described with reference to FIG. 2. The number of winding turns was between 48 turns and 56 turns, and the number of winding turns in the example was 51 turns. The thicknesses of the positive electrode, the negative electrode, and the separator were 149 μm, 193 μm, and 13 μm, respectively. The thicknesses of the positive electrode and the negative electrode were the thicknesses including the thickness of the active material layer. The thicknesses of the positive electrode current collector and the negative electrode current collector were 15 μm and 10 μm, respectively. The lengths of the positive electrode and the negative electrode in the winding direction were 3948 mm and 4045 mm, respectively.

[0437] In each example, the height variable section (circle 2) of the segmented piece 61 was set such that the minimum height of the segmented piece 61 started from a radius of 5 mm and was 3 mm. Also, in each example, the height of the segmented piece 61 was increased by 1 mm each time the radius increased by 1 mm, and the maximum height of the segmented piece 61 was varied from 4 mm to 10 mm.

[0438] Specifically, in Example 1-1, the height variable range (circle 2) of the segmented slice 61 is 5 mm to 6 mm, and the height of the segmented slice 61 changes from a radius of 3 mm to 4 mm. In Example 1-2, the height variable range (circle 2) of the segmented slice 61 is 5 mm to 7 mm, and the height of the segmented slice 61 changes from 3 mm to 5 mm. In Example 1-3, the height variable range (circle 2) of the segmented slice 61 is 5 mm to 8 mm, and the height of the segmented slice 61 changes from 3 mm to 6 mm. In Example 1-4, the height variable range (circle 2) of the segmented slice 61 is 5 mm to 9 mm, and the height of the segmented slice 61 changes from 3 mm to 7 mm. In Example 1-5, the height variable range (circle 2) of the segmented slice 61 is 5 mm to 10 mm, and the height of the segmented slice 61 changes from 3 mm to 8 mm. In Example 1-6, the height variable range (circle 2) of the segmented slice 61 is 5 mm to 11 mm, and the height of the segmented slice 61 changes from 3 mm to 9 mm. In Example 1-7, the height variable range (circle 2) of the segmented slice 61 is 5 mm to 12 mm, and the height of the segmented slice 61 changes from 3 mm to 10 mm. In Examples 1-1 to 1-7, the height of the segmented slice 61 is uniform from the radius corresponding to the upper limit of the height variable range (circle 2) to the outer circumference. As an example, in Example 1-7, the height of the segmented slice 61 is uniform at 10 mm from a radius of 12 mm to 22 mm. On the other hand, in the electrode assembly of the comparative example, the height of the segmented slice 61 was maintained at a single height of 3 mm from a radius of 5 mm to a radius of 22 mm.

[0439] Figure 10c is a graph showing the result of counting the number of stacked segmented slices 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 1-1 to 1-7 and the comparative example. Substantially the same result is shown in the bent surface region of the negative electrode. The horizontal axis of the graph is the radius with respect to the center of the core, and the vertical axis of the graph is the number of stacked segmented slices counted at each radius point. The same applies to FIGS. 10d and 10e described later.

[0440] Referring to Fig. 10c, the number-average layer interval b1 of the segmented slices commonly appears in Examples 1-1 to 1-7 and Comparative Example 1. The number-average layer interval b1 is the radius interval of the flat region in each graph. The length of the number-average layer interval b1 increases as the maximum height of the segmented slice decreases, and the number-average layer interval b1' of the comparative example is the longest. On the other hand, the number of layers of the segmented slice increases as the maximum height h N of the segmented slice increases. That is, if the maximum height h N of the segmented slice increases and the width of the height variable interval (circle 2) of the segmented slice increases, the number of layers of the segmented slice increases while the width of the number-average layer interval b1 decreases. Outside the number-average layer interval b1, a layer number decrease interval b2 appears where the number of layers of the segmented slice decreases as the radius increases. The layer number decrease interval b2 is the radius interval where the number of layers of the segmented slice decreases as the radius of the electrode assembly increases. The number-average layer interval b1 and the layer number decrease interval b2 are adjacent in the radial direction and are complementary to each other. That is, if the length of one interval increases, the length of the other interval decreases. Also, in the layer number decrease interval b2, the amount of decrease in the number of layers is proportional to the distance from the number-average layer interval b1.

[0441] From the side of the number of layers of the segmented slice, in Examples 1-1 to 1-7, the number of layers of the segmented slice in the number-average layer interval b1 of the segmented slice is 10 or more. The region where the number of layers of the segmented slice is 10 or more can be set as a preferable welding target region. The welding target region is the section where at least a part of the current collector is welded.

[0442] In Examples 1-1 to 1-7, the number-average layer interval b1 starts from the radius point where the height variable interval (circle 2) of the segmented slice starts. That is, the height variable interval (circle 2) starts from a radius of 5 mm and extends to the outer peripheral side.

[0443] Table 4 below shows the results of calculating, in Examples 1-1 to 1-7 and Comparative Example 1, the ratio of the length of the segment omission section (c, circle 1 in Fig. 10a) to the radius (b - a) of the electrode assembly excluding the core with respect to the positive electrode, the ratio (e / f) of the length of the layer number average section b1 to the length (f) from the radius point (5 mm) where the layer number average section starts to the outermost point (22 mm) of the electrode assembly, the ratio (d / f) of the length of the height variable section (d) of the segment to the length (f) from the radius point (5 mm) where the layer number average section starts to the outermost point (22 mm) of the electrode assembly, the ratio (h) of the length 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 length 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.

[0444] The negative electrode is substantially the same as the positive electrode in other parameters, except that it shows a difference of 0.1 to 1.2% with respect to the parameter h. The sum of the ratios h, i, and j is slightly different from 100%. The reason is that there is a section without a segment in the second part B3 corresponding to the non-coated part on the outer peripheral side of the electrode. For example, in the case of Example 1-1, there is no segment in the second part B3 corresponding to about 4% of the total length of the electrode. In Table 4, a to f are parameters based on the length in the radial direction, and h, i, and j are parameters based on the longitudinal direction of the electrode before the electrode is wound as an electrode assembly. Also, the parameters corresponding to the ratio (%) are values obtained by rounding off the first decimal place. These are substantially the same in Tables 5 and 6 described later.

[0445]

Table 4

[0446] Referring to Examples 1-1 to 1-7 in Table 4, the number of laminated segments is 11 to 26, and the ratio (d / f) of the height variable interval (d) to the radius interval (f) including the segmented slices is 6% to 41%. Also, the ratio (e / f) of the number-of-layers uniform interval (e) to the radius interval (f) including the segmented slices is 47% to 82%. Further, the ratio (c / (b-a)) of the segmented-slice omission interval (c, circle 1 in Fig. 10a) to the radius (b-a) of the electrode assembly excluding the core is 15%. Also, the ratio of the length of the electrode region corresponding to the segmented-slice omission interval (first part B1) to the overall length of the electrode is 6%, the ratio of the length of the electrode region corresponding to the height variable interval to the overall length of the electrode is 3% to 32%, and the ratio of the length of the electrode region corresponding to the height uniform interval to the overall length of the electrode is 59% to 87%. The number of laminations (g) in the number-of-layers uniform interval is 10 or more for all of Examples 1-1 to 1-7. The number-of-layers uniform interval (e) decreases as the height variable interval (d) of the segmented slices increases, but the number of laminated segments (g) of the segmented slices increases in the number-of-layers uniform interval (e). Preferably, the number-of-layers uniform interval (e) in which the number of laminated segments (g) of the segmented slices is 10 or more can be set as the welding target region.

[0447] Cylindrical batteries having form factors of 1865 and 2170 have a radius of the electrode assembly of about 9 mm to 10 mm. Therefore, for conventional cylindrical batteries, as in Examples 1-1 to 1-7, the radial length of the segmented region (f) cannot be ensured at a level of 17 mm, and the length of the number-of-layers uniform interval (e) in which the number of laminated segments is 10 or more cannot be ensured at a level of 8 mm to 14 mm. In a conventional cylindrical battery, when the radius of the core is designed to be 2 mm, the same as in Examples 1-1 to 1-7, the radius interval where the segmented slices can be arranged is only substantially 7 mm to 8 mm. Also, in a conventional cylindrical battery, the length in the winding direction of the electrode is at a level of 600 mm to 980 mm. Such a short electrode length is only about 15% to 24% of the electrode lengths (positive electrode 3948 mm, negative electrode 4045 mm) used in Examples 1-1 to 1-7. Therefore, the numerical ranges for parameters h, i, and j cannot be easily derived from the design specifications of conventional cylindrical batteries.

[0448] Next, when the maximum height h of the segment in the variable height interval of the segment (circle 2 in FIG. 10a) is the same, with a specific example, how the number of stacked segments changes along the radial direction of the bent surface region F due to the change in the minimum height h1 of the segment will be described. N When the maximum height h of the segment in the variable height interval of the segment (circle 2 in FIG. 10a) is the same, with a specific example, how the number of stacked segments changes along the radial direction of the bent surface region F due to the change in the minimum height h1 of the segment will be described.

[0449] The electrode assemblies of Examples 2-1 to 2-5 have a radius of 22 mm and the core C has a diameter of 4 mm. The minimum height h1 in the variable height interval of the segment 61 (circle 2 in FIG. 10a) is the same as 4 mm, and the maximum height h N was changed in 1 mm increments from 6 mm to 10 mm. Therefore, the electrode assemblies of Examples 2-1 to 2-5 have widths of the variable height intervals of the segments (circle 2 in FIG. 10a) of 2 mm, 3 mm, 4 mm, 5 mm, and 6 mm respectively, and the segment omission interval (circle 1 in FIG. 10a) is a radius interval from a radius of 2 mm to 6 mm.

[0450] The electrode assemblies of Examples 3-1 to 3-4 have a radius of 22 mm and the core C has a diameter of 4 mm. The minimum height h1 in the variable height interval of the segment 61 (circle 2 in FIG. 10a) is the same as 5 mm, and the maximum height h N was changed in 1 mm increments from 7 mm to 10 mm. Therefore, the electrode assemblies of Examples 3-1 to 3-4 have widths of the variable height intervals of the segments (circle 2 in FIG. 10a) of 2 mm, 3 mm, 4 mm, and 5 mm respectively, and the segment omission interval (circle 1 in FIG. 10a) is a radius interval from a radius of 2 mm to 7 mm.

[0451] The electrode assemblies of Examples 4-1 to 4-3 have a radius of 22 mm and the core C has a diameter of 4 mm. The minimum height h1 in the variable height interval of the segment 61 (circle 2 in FIG. 10a) is the same as 6 mm, and the maximum height h N was changed in 1 mm increments from 8 mm to 10 mm. Therefore, the electrode assemblies of Examples 4-1 to 4-3 have widths of the variable height intervals of the segments (circle 2 in FIG. 10a) of 2 mm, 3 mm, and 4 mm respectively, and the segment omission interval (circle 1 in FIG. 10a) is a radius interval from a radius of 2 mm to 8 mm.

[0452] The electrode assemblies of Examples 5-1 to 5-2 have a radius of 22 mm and the core C has a diameter of 4 mm. The minimum height h1 in the height variable section of the segment (circle 2 in Fig. 10a) is the same as 7 mm, and the maximum height h N was changed in 1 mm increments from 9 mm to 10 mm. Therefore, the electrode assemblies of Examples 5-1 to 5-2 have widths of 2 mm and 3 mm, respectively, in the height variable section of the segment (circle 2 in Fig. 10a), and the segment omission section (circle 1 in Fig. 10a) is a radial section from a radius of 2 mm to 9 mm.

[0453] Fig. 10d is a graph showing the result 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 2-1 to 2-5, Examples 3-1 to 3-4, Examples 4-1 to 4-3, Examples 5-1 and 5-2. Substantially the same results are shown in the bent surface region of the negative electrode.

[0454] In Fig. 10d, graph (a) is for Examples 2-1 to 2-5, graph (b) is for Examples 3-1 to 3-4, graph (c) is for Examples 4-1 to 4-3, and graph (d) is for Examples 5-1 and 5-2, showing the result of counting the number of stacked segments along the radial direction in the bent surface region F.

[0455] Referring to Fig. 10d, a stacked segment number uniform section b1 commonly appears in all examples. The stacked segment number uniform section b1 is a radial section of the flat region in the graph. The length of the stacked segment number uniform section b1 increases as the maximum height h of the segment decreases when the minimum height h1 of the segment is the same. Also, the length of the stacked segment number uniform section b1 increases as the minimum height h1 of the segment decreases when the maximum height h of the segment is the same. On the other hand, in the stacked segment number uniform section b1, the number of stacked segments increases as the maximum height h of the segment increases. In the examples, a stacked segment number decreasing section b2 also appears adjacent to the stacked segment number uniform section b1. N of the segment decreases. Also, the length of the stacked segment number uniform section b1 increases as the minimum height h1 N of the segment decreases when the maximum height h of the segment is the same. On the other hand, in the stacked segment number uniform section b1, the number of stacked segments increases as the maximum height h N of the segment increases. In the examples, a stacked segment number decreasing section b2 also appears adjacent to the stacked segment number uniform section b1.

[0456] In the embodiments, the number of laminations of the sliced sections in the lamination number uniform interval b1 is all 10 or more. Preferably, the region where the number of laminations of the sliced sections is 10 or more can be set as a preferable welding target region.

[0457] In the embodiments, the lamination number uniform interval b1 starts from the radial point where the height variable interval of the sliced section (circle 2 in Fig. 10a) starts. In Examples 2-1 to 2-5, the height variable interval of the sliced section (circle 2 in Fig. 10a) starts from 6 mm and extends to the outer peripheral side. In Examples 3-1 to 3-4, the height variable interval of the sliced section (circle 2 in Fig. 10a) starts from 7 mm and extends to the outer peripheral side. In Examples 4-3 to 4-3, the height variable interval of the sliced section (circle 2 in Fig. 10a) starts from 8 mm and extends to the outer peripheral side. In Examples 5-1 and 5-2, the height variable interval of the sliced section (circle 2 in Fig. 10a) starts from 9 mm and extends to the outer peripheral side.

[0458] In Table 5 below, 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, the ratio (e / f) of the length of the lamination number uniform interval to the length from the radial point (6 mm, 7 mm, 8 mm, 9 mm) where the lamination number uniform interval starts to the outermost point (22 mm) of the electrode assembly, the ratio (d / f) of the length of the height variable interval (circle 2) of the sliced section to the length from the radial point (6 mm, 7 mm, 8 mm, 9 mm) where the lamination number uniform interval starts to the outermost point (22 mm) of the electrode assembly, and other various parameters are shown as the calculated results.

[0459]

Table 5

[0460] Referring to Examples 2-5, 3-4, 4-3, and 5-2 in Table 5 together with Figs. 10a and 10d, the maximum height h of the sliced section in the height variable interval (circle 2) of the sliced section Nis the same at 10 mm, but the minimum height h1 of the segmented slice increases by 1 mm each for 4 mm, 5 mm, 6 mm, and 7 mm, and the length of the height variable section (circle 2) decreases by 1 mm each for 6 mm, 5 mm, 4 mm, and 3 mm. In the four embodiments, the ratio (e / f) of the layer number uniform section is the largest at 69% for Embodiments 2 - 5 and the smallest at 38% for Embodiment 5 - 2, and the number of layers in the layer number uniform section is all equal. From the results shown in Table 5, the maximum height h of the segmented slice N is the same, it can be seen that as the minimum height h1 of the segmented slice decreases and the width of the height variable section (circle 2) of the segmented slice increases, the width of the layer number uniform section also increases proportionally. The reason is that the smaller the minimum length h1 of the segmented slice, the closer the radius point where the segmented slice starts is to the core side, and the area where the segmented slices are stacked expands towards the core side.

[0461] Referring to Table 5, it can be seen that the number of layers of the segmented slices is 16 - 26, the ratio (d / f) of the height variable section (circle 2) of the segmented slice is 13% - 38%, and the ratio (e / f) of the layer number uniform section is 31% - 69%. Also, the ratio (c / (b - a)) of the segmented slice omission section (circle 1) to the radius (b - a) of the electrode assembly excluding the core is 20% - 35%. Also, the ratio of the length of the electrode region corresponding to the segmented slice omission section (circle 1) to the total length of the electrode is 10% - 20%, the ratio of the length of the electrode region corresponding to the height variable section (circle 2) to the total length of the electrode is 6% - 25%, and the ratio of the length of the electrode region corresponding to the height uniform section (circle 3) to the total length of the electrode is 62% - 81%.

[0462] Cylindrical batteries having form factors of 1865 and 2170 have an electrode assembly with a radius of approximately 9 mm to 10 mm. Therefore, as in the embodiments, the radial length of the slitting section (f) cannot be ensured at the level of 13 mm to 16 mm, and while ensuring that the length of the slitting section omission section (c, circled 1) is about 4 mm to 7 mm, it is not possible to ensure that the length of the evenly laminated section (e) with 10 or more layers of slitting sections is at the level of 5 mm to 11 mm. In a conventional cylindrical battery, when the radius of the core is designed to be 2 mm as in the embodiments, the radial section where the slitting sections can be arranged is only substantially 7 mm to 8 mm. Also, in a conventional cylindrical battery, the length in the winding direction of the electrodes is at the level of 600 mm to 980 mm. Such a short electrode length is only about 15% to 24% of the electrode lengths in the embodiments (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.

[0463] Next, when the minimum height h1 and the maximum height h of the slitting sections are the same in the height variable section (circled 2) of the slitting sections, it will be described with specific examples how the number of layers of the slitting sections changes along the radial direction of the bent surface region F according to the diameter of the core C of the electrode assembly. N When they are the same, it will be described with specific examples how the number of layers of the slitting sections changes along the radial direction of the bent surface region F according to the diameter of the core C of the electrode assembly.

[0464] 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 slitting sections in the height variable section (circled 2) of the slitting sections 61 is the same as 3 mm, and the maximum height h of the slitting sections N was changed in 1 mm increments from 5 mm to 10 mm. Therefore, the electrode assemblies of Examples 6-1 to 6-6 have widths of 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, and 7 mm respectively in the height variable section (circled 2) of the slitting sections, and the slitting section omission section (circled 1) is a radial section from a radius of 4 mm to 7 mm.

[0465] 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 slitting sections in the height variable section (circled 2) of the slitting sections 61 is the same as 3 mm, and the maximum height h of the slitting sectionsN It was changed in 1 mm increments from 5 mm to 10 mm. Therefore, in the electrode assemblies of Examples 7-1 to 7-6, the widths of the height variable sections (circle 2) of the segmented slices are 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, and 7 mm respectively, and the segmented slice omission section (circle 1) is the same as the radius section from a radius of 2 mm to 5 mm.

[0466] Figure 10e is a graph showing the result of counting the number of stacked segmented slices 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 result appears in the bent surface region of the negative electrode.

[0467] In Figure 10e, graph (a) shows the result of counting the number of stacked segmented slices measured along the radial direction in the bent surface region F for Examples 6-1 to 6-6, and graph (b) shows the result for Examples 7-1 to 7-6.

[0468] Referring to Figure 10e, a stacked number uniform section b1 of the segmented slices commonly appears in all the examples. The stacked number uniform section b1 is the radius section of the flat region in the graph. The length in the radial direction of the stacked number uniform section b1 increases as the maximum height h of the segmented slice decreases when the minimum height h1 of the segmented slice is the same. On the other hand, in the stacked number uniform section b1, the number of stacked segmented slices increases as the maximum height h of the segmented slice increases. In the examples, a stacked number decreasing section b2 is confirmed adjacent to the stacked number uniform section b1. N N increases. In the examples, a stacked number decreasing section b2 is confirmed adjacent to the stacked number uniform section b1.

[0469] In the examples, the number of stacked segmented slices in the stacked number uniform section b1 is all 10 or more. Preferably, the region where the number of stacked segmented slices is 10 or more can be set as a preferable welding target region.

[0470] ​In the examples, the stacked number average section b1 starts from the radial position where the height variable section (circle 2) of the sliced section begins. In the cases of Examples 6-1 to 6-6, the radius where the height variable section (circle 2) of the sliced section begins is 7 mm, and in the cases of Examples 7-1 to 7-6, the radius where the height variable section (circle 2) of the sliced section begins is 5 mm.

[0471] In Table 6 below, for Examples 6-1 to 6-6 and Examples 7-1 to 7-6, the ratio (e / f) of the length of the stacked number average section to the length from the radial position (7 mm, 5 mm) where the stacked number average section begins to the outermost position (22 mm) of the electrode assembly, the ratio (d / f) of the length of the height variable section (circle 2) of the sliced section to the length from the radial position (7 mm, 5 mm) where the stacked number average section begins to the outermost position (22 mm) of the electrode assembly, and other calculation results of various parameters are shown.

[0472]

Table 6

[0473] Referring to FIG. 10a and Examples 6-6 and 7-6 in Table 6, the minimum height h1 and the maximum height h of the sliced section in the height variable section (circle 2) of the sliced section NThey are the same at 3 mm and 10 mm respectively. However, in Example 6-6, the radius of the core is 2 mm larger than that in Example 7-6. Therefore, compared with Example 7-6, the lamination number average section (e) and the cut section (f) in Example 6-6 are 2 mm smaller, and the number of laminations of the cut sections in the lamination number average section is the same. Such a result is due to the difference in the radius of the core. From the results shown in Table 6, when the width of the height variable section (round 2) of the cut section is the same, it can be seen that the smaller the radius (a) of the core, the smaller the ratio (d / f) of the height variable section (round 2), while the ratio (e / f) of the lamination number average section increases. Referring to Table 6, it can be seen that the number of laminations of the cut section is 13 to 26, the ratio (d / f) of the height variable section (round 2) of the cut section is 12% to 47%, and the ratio (e / f) of the length of the lamination number average section is 40% to 76%. Also, the ratio (c / (b - a)) of the cut section omission section (round 1) to the radius (b - a) of the electrode assembly excluding the core is 15% to 17%. Further, the ratio of the length of the electrode region corresponding to the cut section omission section (round 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 (round 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 (round 3) to the total length of the electrode is 59% to 83%.

[0474] Cylindrical batteries having form factors of 1865 and 2170 have a radius of the electrode assembly of approximately 9 mm to 10 mm. Therefore, as in the embodiment, the radial length of the cut section interval (f) cannot be ensured at the level of 15 mm to 17 mm, and while ensuring the length of the cut section omission interval (circle 1) to be about 3 mm, the length of the number-of-layers uniform interval (e) where the number of layers of the cut sections is 10 or more cannot be ensured at the level of 6 mm to 13 mm. In a conventional cylindrical battery, when the radius of the core is designed to be the same as 2 mm to 4 mm in the embodiment, the radius interval where the cut sections can be arranged is only substantially 5 mm to 8 mm. Also, in a conventional cylindrical battery, the length in the winding direction of the electrode is at the level of 600 mm to 980 mm. Such a short electrode length is only at the level of about 15% to 24% compared to the electrode lengths in the embodiment (the positive electrode is 3948 mm and the negative electrode is 4045 mm). Therefore, the numerical ranges for parameters h, i, and j cannot be easily derived from the design specifications of the conventional cylindrical battery.

[0475] Taking into comprehensive consideration the data in Tables 4 to 6, the number of layers of the cut sections in the number-of-layers uniform interval of the cut sections can be 11 to 26. Also, the ratio (d / f) of the height variable interval (circle 2) of the cut sections can be 6% to 47%. Also, the ratio (e / f) of the number-of-layers uniform interval can be 31% to 82%. Also, the ratio (c / (b - a)) of the length of the cut section omission interval (circle 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 cut section omission interval (circle 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 height variable interval (circle 2) of the cut sections 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 height uniform interval (circle 3) of the cut sections to the total length of the electrode can be 59% to 87%.

[0476] On the other hand, the parameters described through Tables 4 to 6 are the radius of the core (a); the radius of the electrode assembly (b); the minimum height h1 and the maximum height h in the height variable interval (circle 2) of the cut sections N; The change amount Δh of the height of the sub-slice per 1 mm increase in radius; It can vary depending on design factors including the thicknesses of the positive electrode, negative electrode, and separator.

[0477] Therefore, the number of stacked sub-slices in the stacked number average interval of the sub-slices can be extended from 10 to 35. The ratio (d / f) of the height variable interval (circle 2) of the sub-slices can be extended from 1% to 50%. Also, the ratio (e / f) of the stacked number average interval can be extended from 30% to 85%. Also, the ratio of the length of the sub-slice omission interval (circle 1) to the radius of the electrode assembly excluding the core (c / (b - a)) can be extended from 10% to 40%. Also, the ratio of the length of the electrode region corresponding to the sub-slice omission interval (circle 1) to the total length of the electrode (length in the winding direction) can be extended from 1% to 30%. Also, the ratio of the length of the electrode region corresponding to the height variable interval (circle 2) of the sub-slices to the total length of the electrode can be extended from 1% to 40%. Also, the ratio of the length of the electrode region corresponding to the height uniform interval (circle 3) of the sub-slices to the total length of the electrode can be extended from 50% to 90%. In the above-described embodiments, the maximum height h of the sub-slices included in the height variable interval (circle 2) and the height uniform interval (circle 3) N The height index N is 2 to 8. For example, referring to Table 4, the height indices 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 amount Δh of the height of the sub-slices in the radial direction of the electrode assembly. When the radial length of the height variable interval (circle 2) is fixed, as the change amount Δh of the height of the sub-slices decreases, the height index N increases accordingly, and vice versa is also possible. Preferably, the height index N can be further extended from 2 to 20, and optionally from 2 to 30.

[0478] In the bent surface region F formed at the upper and lower parts of the electrode assembly, the stacked number average interval can be used as the welding target region of the current collector.

[0479] Preferably, the welding region of the current collector preferably overlaps with the stacked number average interval by at least 50% in the radial direction of the electrode assembly, and the higher the overlapping ratio, the more preferable.

[0480] Preferably, other regions of the welding region of the current collector that do not overlap with the uniform lamination number interval may overlap with the lamination number decreasing interval adjacent to the uniform lamination number interval in the radial direction.

[0481] More preferably, other regions of the welding region of the current collector that do not overlap with the uniform lamination number interval may overlap with the region where the number of overlapping segments in the lamination number decreasing interval is 10 or more.

[0482] Welding the current collector to the region where the number of laminations of the segment is 10 or more is preferable in terms of the welding strength and preventing damage to the separation film and the active material layer during welding. In particular, it is useful when welding the current collector using a high-output laser with high transmission characteristics.

[0483] If the uniform lamination number interval with 10 or more segments laminated and the current collector are welded by laser, even if the output of the laser is increased to improve the welding quality, since the uniform lamination number interval mostly absorbs the energy of the laser to form a weld bead, it is possible to prevent the phenomenon that the separation film and the active material layer below the bent surface region F are damaged by the laser.

[0484] In addition, since the number of laminations of the segments in the region irradiated with the laser is 10 or more, a weld bead is formed with sufficient volume and thickness. Therefore, the welding strength is sufficiently ensured, and the resistance of the welding interface can be reduced to a level suitable for rapid charging.

[0485] The output of the laser 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 in proportion to the number of laminations of the segments. This is because as the number of laminations increases, the volume of the weld bead formed by the laser becomes larger. The weld bead is formed while the material of the current collector and the material of the segment are melted together. Therefore, when the volume of the weld bead is large, the current collector and the bent surface region are more strongly bonded, and the contact resistance of the welding interface becomes lower.

[0486] Preferably, the welding strength is 2 kgf / cm 2 or more, more preferably 4 kgf / cm 2 or more. The maximum welding strength can vary depending on the output of the laser welding apparatus. As an example, the welding strength is preferably 8 kgf / cm 2 or less, more preferably 6 kgf / cm 2 or less. However, the present invention is not limited thereto.

[0487] When the welding strength satisfies the above numerical range, even if intense vibration is applied to the electrode assembly along the winding axis direction and / or the radial direction, the physical properties of the welding interface do not deteriorate, and since the volume of the weld bead is sufficient, the resistance of the welding interface can also be reduced.

[0488] The output of the laser for satisfying the conditions of the welding strength varies depending on the laser apparatus, but can be appropriately adjusted in the range of 250 W to 320 W or in the range of 40% to 100% of the maximum laser output specification provided by the corresponding apparatus.

[0489] The welding strength can be defined as the tensile force per unit area (kgf / cm 2 ) of the current collector when the current collector begins to separate from the bent surface region F. 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 the critical value, the segmented piece begins to separate from the welding interface. At this time, the value obtained by dividing the tensile force applied to the current collector by the area of the current collector corresponds to the welding strength.

[0490] In the bent surface region F, the segmented pieces are laminated in a plurality of layers. According to the above-described embodiment, the number of laminated segmented pieces can increase from a minimum of 10 to a maximum of 35.

[0491] The thickness of the positive current collector (foil) constituting the non-patterned portion 43 is 10 μm to 25 μm, and the thickness of the negative current collector (foil) constituting the non-patterned portion 43 can be 5 μm to 20 μm. Therefore, the bent surface region F of the positive electrode may include a region where the total lamination thickness of the segmented pieces is 100 μm to 875 μm. Also, the bent surface region F of the negative electrode may include a region where the total lamination thickness of the segmented pieces is 50 μm to 700 μm.

[0492] FIG. 10f is a top view of an electrode assembly showing a lamination number average section b1 and a lamination number decreasing section b2 in the bent surface region F of the segmented pieces 61, 61' according to an embodiment of the present invention.

[0493] Referring to FIG. 10f, the region between the two circles indicated by the thick solid line corresponds to the bent surface region F of the segmented piece, the region between the two circles indicated by the dashed-dotted line corresponds to the lamination number average section b1 where the lamination number of the segmented piece is 10 or more, and the outer region of the lamination number average section b1 corresponds to the lamination number decreasing section b2.

[0494] As an example, if the current collector P c is welded to the bent surface region F, a welding pattern W c is generated on the surface of the current collector P p . The welding pattern W p can be an array of a line pattern or a dot pattern. The welding pattern W p corresponds to the welding region and can overlap with the lamination number average section b1 of the segmented piece by 50% or more along the radial direction. Therefore, a part of the welding pattern W p is included in the lamination number average section b1, and the remaining welding pattern W p can be included in the lamination number decreasing section b2 outside the lamination number average section b1. Of course, in order to maximize the welding strength and reduce the resistance of the welding region, the entire welding pattern W p can overlap with the lamination number average section b1.

[0495] The area of the bent surface region F can be defined as the sum of the area of the uniform lamination number section b1 of the segment and the area of the lamination number decreasing section b2. Since the ratio (e / f) of the uniform lamination number section b1 is 30% to 85%, preferably 31% to 82%, the ratio of the area of the uniform lamination number section b1 to the area of the bent surface region F is 9% (30 2 / 100 2 ) to 72% (85 2 / 100 2 ), preferably 10% (31 2 / 100 2 ) to 67% (82 2 / 100 2 ).

[0496] Preferably, the end of the portion where the current collector P c contacts the bent surface region F can cover the ends of the segments 61, 61' bent toward the core C side at the last winding turn of the uniform height section (circle 3). In this case, with the segments 61, 61' pressed by the current collector P c , a welding pattern W p is formed, so that the current collector P c and the bent surface region F are strongly bonded. As a result, the segments 61, 61' laminated in the winding axis direction are closely adhered to each other, so that the resistance at the welding interface is also reduced, and the phenomenon of the segments 61, 61' rising can be prevented.

[0497] On the other hand, the bending direction of the segment may be opposite to the above-described direction. That is, the segment may be bent from the core side to the outer peripheral side. In this case, the pattern in which the height of the segment changes along the winding direction (X-axis direction) can be opposite to the above-described embodiment (deformed form). For example, the height of the segment can gradually decrease from the core to the outer peripheral side. Also, the structure applied to the first part B1 and the structure applied to the second part B3 can be replaced with each other. Preferably, the height of the segment is gradually decreased from the core side to the outer peripheral side, and when the segment closest to the outer periphery of the electrode assembly is bent to the outer peripheral side, the height change pattern of the segment is designed so that the end of the segment does not protrude outside the outer periphery of the electrode assembly.

[0498] The electrode structure of the above-described embodiment (variant form) can be applied to at least one of the first electrode and the second electrode having different polarities included in a jelly roll type or other types of electrode assemblies well-known in the art. Further, when the electrode structure of the embodiment (variant form) is applied to one of the first electrode and the second electrode, a conventional electrode structure can be applied to the other. Further, the electrode structures applied to the first electrode and the second electrode may not be the same and may be different.

[0499] As an example, when the first electrode and the second electrode are a positive electrode and a negative electrode, respectively, any one of the embodiments (variant forms) can be applied to the first electrode, and a conventional electrode structure (see FIG. 1) can be applied to the second electrode.

[0500] As another example, when the first electrode and the second electrode are a positive electrode and a negative electrode, respectively, any one of the embodiments (variant forms) can be selectively applied to the first electrode, and any one of the embodiments (variant forms) can be selectively applied to the second electrode.

[0501] In one embodiment of 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 used without limitation as long as they are active materials known in the art.

[0502] As an example, the positive electrode active material may include an alkali metal compound represented by the general chemical formula A[A x M y O 2+z (A includes at least one element of Li, Na, and K; M includes at least one element selected from Ni, Co, Mn, Ca, Mg, Al, Ti, Si, Fe, Mo, V, Zr, Zn, Cu, Al, Mo, Sc, Zr, Ru, and Cr; x≧0, 1≦x + y≦2, -0.1≦z≦2; the stoichiometric coefficients x, y, and z are selected so that the compound maintains electrical neutrality).

[0503] 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. 1O2-(1-x)Li2M 2 O3(M 1 contains at least one element having an average oxidation state of 3; M 2 contains at least one element having an average oxidation state of 4; 0 ≦ x ≦ 1).

[0504] 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 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 a lithium metal phosphate represented by Li3M2(PO4)3 [M contains at least one element selected from Ti, Si, Mn, Fe, Co, V, Cr, Mo, Ni, Al, Mg and Al].

[0505] As yet another example, the positive electrode active material is a layered compound such as lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), or a compound substituted with one or more transition metals; the chemical formula Li 1+x Mn 2-x O4 (x = 0 to 0.33), lithium manganese oxides such as LiMnO3, LiMn2O3, LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O5, LiV3O4, V2O5, Cu2V2O7; the chemical formula LiNi 1-x M xNickel-site type lithium nickel oxide represented by O2 (M = Co, Mn, Al, Cu, Fe, Mg, B or Ga, x = 0.01 to 0.3); chemical formula LiMn 2-x M x Lithium manganese composite oxide represented by O2 (M = Co, Ni, Fe, Cr, Zn or Ta, x = 0.01 to 0.1) or Li2Mn3MO8 (M = Fe, Co, Ni, Cu or Zn); LiMn2O4 in which part of the lithium in the chemical formula is substituted with alkaline earth metal ions; disulfide compound; a lithium intercalation material such as a composite oxide formed by Fe2(MoO4)3 or a combination thereof may be used as the main component.

[0506] The positive electrode current collector has, for example, a thickness of 3 μm to 500 μm. Such a positive electrode current collector is not particularly limited as long as it has conductivity without inducing a chemical change in the battery. For example, stainless steel, aluminum, nickel, titanium, fired carbon, or those obtained by surface treatment of aluminum or stainless steel with carbon, nickel, titanium, silver, etc. can be used. The positive electrode current collector may form fine irregularities on its surface to enhance the adhesive force of the positive electrode active material, and can be used in various forms such as films, sheets, foils, nets, porous bodies, foams, and non-woven fabrics.

[0507] A conductive material may be further mixed with the positive electrode active material particles. Such a conductive material is added, for example, in an amount of 1 to 50% by weight based on the total weight of the mixture containing the positive electrode active material. Such a conductive material is not particularly limited as long as it has high conductivity without inducing a chemical change in the battery. For example, graphite such as natural graphite and artificial graphite; carbon blacks such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black; conductive fibers such as carbon fibers and metal fibers; metal powders such as carbon fluoride, aluminum, and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives can be used.

[0508] Preferably, the positive electrode active material may include primary particles and / or secondary particles formed by aggregation of the primary particles.

[0509] The negative electrode is manufactured by applying and drying negative electrode active material particles on a negative electrode current collector, and may further contain components such as the above-described conductive material, binder, solvent, etc., as necessary.

[0510] The negative electrode current collector has a thickness of, for example, 3 μm to 500 μm. Such a negative electrode current collector is not particularly limited as long as it has conductivity without inducing a chemical change in the battery, and examples include copper, stainless steel, aluminum, nickel, titanium, fired carbon, those obtained by surface treatment of the surface of copper or stainless steel with carbon, nickel, titanium, silver, etc., aluminum-cadmium alloy, etc. can be used. Also, similar to the positive electrode current collector, fine irregularities may be formed on the surface to strengthen the bonding force of the negative electrode active material, and it can be used in various forms such as films, sheets, foils, nets, porous bodies, foams, non-woven bodies, etc.

[0511] As an example, as the negative electrode active material, a carbon material, lithium metal or lithium metal compound, silicon or silicon compound, tin or tin compound, etc. can be used. Metal oxides such as TiO2 and SnO2 with a potential of less than 2V can also be used as the negative electrode active material. As the carbon material, both low-crystalline carbon and high-crystalline carbon can be used.

[0512] As another example, the negative electrode active material is, for example, carbon such as graphitizable carbon, graphite-based carbon; Li x Fe2O3 (0 ≦ x ≦ 1), Li x WO2 (0 ≦ x ≦ 1), Sn x Me 1-x Me’ y O zMetal composite oxides of (Me: Mn, Fe, Pb, Ge; Me’: Al, B, P, Si, Group 1, Group 2, Group 3 elements of the periodic table, halogen; 0 < x ≤ 1; 1 ≤ y ≤ 3; 1 ≤ z ≤ 8); lithium metal; lithium alloy; silicon-based alloy; tin-based alloy; oxides such as SnO, SnO2, PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, Bi2O5; conductive polymers such as polyacetylene; Li-Co-Ni-based materials, etc. can be used.

[0513] The binder polymer that can be used for the electrode is a component that assists the binding of the electrode active material particles and the conductive material, etc., and the binding to the electrode current collector, and is added, for example, at 1 to 50% by weight based on the total weight of the mixture containing the electrode active material. Examples of such binder polymers include any one binder polymer selected from the group consisting of polyvinylidene fluoride - hexafluoropropylene, polyvinylidene fluoride - trichloroethylene, polymethyl methacrylate, polybutyl acrylate, polyacrylonitrile, polyvinyl pyrrolidone, polyvinyl acetate, ethylene vinyl acetate copolymer, polyethylene oxide, polyarylate, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl pullulan, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, cyanoethyl sucrose, pullulan, and carboxymethyl cellulose, or a mixture of two or more of these, but is not limited thereto.

[0514] Non-limiting examples of the solvent used in the manufacture of the electrode include acetone, tetrahydrofuran, methylene chloride, chloroform, dimethylformamide, N-methyl-2-pyrrolidone (NMP), cyclohexane, water, or a mixture thereof, etc. Such a solvent provides an appropriate level of viscosity so that a slurry coating layer is formed at a desired level on the surface of the electrode current collector.

[0515] The negative electrode includes a current collector and a negative electrode active material layer located on at least one surface of the current collector, the negative electrode active material layer containing a negative electrode active material, a binder polymer, and a conductive material. The negative electrode active material layer is composed of a lower layer region that is in surface contact with the current collector and an upper layer region that extends to the surface of the negative electrode active material layer while being in surface contact with the lower layer region. The lower layer region and the upper layer region may each independently contain at least one or more of graphite and silicon-based compounds as the negative electrode active material.

[0516] The lower layer region contains natural graphite as the negative electrode active material, and the upper layer region may contain artificial graphite as the negative electrode active material.

[0517] The lower layer region and the upper layer region may each independently further contain a silicon-based compound as the negative electrode active material.

[0518] The silicon-based compound may contain one or more of SiOx (0 ≤ x ≤ 2) and SiC.

[0519] According to one embodiment of the present invention, the negative electrode can be manufactured by applying and drying a lower layer slurry containing a lower layer negative electrode active material to a current collector to form a lower layer region, and then applying and drying an upper layer slurry containing an upper layer negative electrode active material on the lower layer region to form an upper layer region.

[0520] Alternatively, according to one embodiment of the present invention, the negative electrode includes the steps of preparing a lower layer slurry containing a lower layer negative electrode active material and an upper layer slurry containing an upper layer negative electrode active material, coating the lower layer slurry on one surface of a negative electrode current collector, and simultaneously or with a predetermined time difference, coating the upper layer slurry on the lower layer slurry, and simultaneously drying the coated lower layer slurry and upper layer slurry to form an active material layer. It can also be manufactured by a method including these steps.

[0521] When manufactured by the latter method, in the portion where the lower layer region and the upper layer region abut in the negative electrode, there may be a mixed region (intermixing) where these different types of active materials are mixed. This is because when forming the active material layer in such a way that the lower slurry containing the lower negative electrode active material and the upper slurry containing the upper negative electrode active material are continuously coated on the current collector simultaneously or with a very short time difference and then dried simultaneously, a predetermined mixing section occurs on the interface where the lower slurry and the upper slurry abut before drying, and then such a mixing section is formed in the layer form of the mixed region while being dried.

[0522] In the negative electrode active material layer according to an embodiment of the present invention, the weight ratio (or the ratio of the loading amount per unit area) of the upper layer region to the lower layer region may be 20:80 to 50:50, specifically 25:75 to 50:50.

[0523] The thicknesses of the lower layer region and the upper layer region of the negative electrode active material layer according to an embodiment of the present invention may not completely match the thicknesses of the coated lower slurry and the coated upper slurry. However, as a result of undergoing a drying or selective rolling process, the thickness ratio of the lower layer region to the upper layer region of the finally obtained negative electrode active material layer according to an embodiment of the present invention may match the thickness ratio of the coated lower slurry to the coated upper slurry.

[0524] According to an embodiment of the present invention, a first slurry (lower slurry) is coated, and a second slurry (upper slurry) is coated on the first slurry simultaneously or with a predetermined time difference, and the predetermined time difference may be a time difference of 0.6 seconds or less, 0.02 seconds to 0.6 seconds, 0.02 seconds to 0.06 seconds, or 0.02 seconds to 0.03 seconds. Since such a time difference during the coating of the first slurry and the second slurry is caused by the coating apparatus, it is more preferable that the first slurry and the second slurry can be coated simultaneously. The second slurry can be coated on the first slurry using an apparatus such as a double slot die.

[0525] In the step of forming the active material layer, after the drying step, a step of rolling the active material layer may be further included. At this time, the rolling may be performed by a method commonly used in the art such as a roll press, and for example, it may be performed at a pressure of 1 to 20 MPa and a temperature of 15 to 30 °C.

[0526] The step of simultaneously drying the slurry for the coated lower layer and the slurry for the upper layer to form the active material layer may be performed by a method commonly used in the art using a device in which a hot air drying device and an infrared drying device are combined.

[0527] The weight percentage of the first binder polymer in the solid content of the lower layer slurry may be the same as or greater than the weight percentage of the second binder polymer in the solid content of the upper layer slurry. According to an embodiment of the present invention, the weight percentage of the first binder polymer in the solid content of the lower layer slurry may be 1.0 to 4.2 times, 1.5 to 3.6 times, or 1.5 to 3 times the weight percentage of the second binder polymer in the solid content of the upper layer slurry.

[0528] When the ratio of the weight percentage of the first binder in the coated lower layer slurry to the weight percentage of the second binder in the coated upper layer slurry satisfies such a range, the binder in the lower layer region will not be excessively reduced, so that detachment of the electrode layer will not occur, and the binder in the upper layer region will not be excessively increased, so that the resistance of the upper part of the electrode is reduced, which is advantageous for rapid charging performance.

[0529] The weight percentage of the first binder polymer in the solid content of the lower layer slurry may be 2 to 30% by weight, or 5 to 20% by weight, and the ratio (% by weight) of the second binder polymer in the solid content of the upper layer slurry may be 0.5 to 20% by weight, 1 to 15% by weight, 1 to 10% by weight, or 2 to 5% by weight.

[0530] The total ratio (% by weight) of the first binder polymer and the second binder polymer in the total solid content of the lower layer slurry and the upper layer slurry may be 2 to 20% by weight, or 5 to 15% by weight.

[0531] The separation membrane has a porous polymer substrate and porous coating layers located on both surfaces of the porous polymer substrate and containing inorganic particles and a binder polymer.

[0532] The porous polymer substrate may be a polyolefin-based porous substrate.

[0533] The polyolefin-based porous substrate may be in the form of a film or a non-woven web. By having such a porous structure, the electrolyte movement between the positive electrode and the negative electrode becomes smooth, the electrolyte impregnation property of the substrate itself is also increased, excellent ionic conductivity can be ensured, and an increase in the resistance inside the electrochemical element is prevented, thereby preventing a performance degradation of the electrochemical element.

[0534] Any planar porous substrate commonly used in electrochemical elements can be used as the polyolefin-based porous substrate used in the present invention, and its material and form can be variously selected according to the purpose.

[0535] The polyolefin-based porous substrate can be, without limitation, a film or a non-woven web formed of high-density polyethylene, low-density polyethylene, linear low-density polyethylene, ultra-high molecular weight polyethylene, polypropylene, or a mixture of two or more of these, but is not limited thereto.

[0536] The polyolefin-based porous substrate may have a thickness of 8 to 30 μm, but this is merely an example, and a thickness outside the above range can also be adopted in consideration of mechanical physical properties and the high-rate charge / discharge characteristics of the battery.

[0537] The non-woven fabric sheet according to an embodiment of the present invention can be formed of polyethylene (PE), polypropylene (PP), or a mixture thereof. For example, the non-woven fabric sheet can be manufactured by fiber spinning. For example, it can be manufactured by using a melt blown method to make the fibers of the material into a fiber-spun shape above the melting point and then performing co-spinning.

[0538] The non-woven fabric sheet may have an elongation rate of 200 to 400%, more preferably 300 to 400%. When the elongation rate is less than 200%, the possibility of contact between the electrodes during nail penetration increases. When it exceeds 400%, during nail penetration, the peripheral portion also stretches and the separation film becomes thinner, resulting in a decrease in barrier properties (blocking properties).

[0539] A large number of pores having an average diameter of 0.1 to 10 μm are formed in the non-woven fabric sheet. When the pore size is less than 0.1 μm, lithium ions and / or electrolytes cannot move smoothly. When the pore size is larger than 10 μm, due to the stretching of the non-woven fabric sheet during nail penetration, there is a possibility that the effect according to an embodiment of the present invention to prevent contact between the positive electrode and the negative electrode cannot be achieved.

[0540] In addition, the non-woven fabric sheet may have a porosity of 40 to 70%. When the porosity is less than 40%, lithium ions and / or electrolytes cannot move smoothly. When the porosity is larger than 70%, due to the stretching of the non-woven fabric sheet during nail penetration, there is a possibility that the effect according to an embodiment of the present invention to prevent contact between the positive electrode and the negative electrode cannot be achieved. The non-woven fabric sheet manufactured in this way may have an air permeability of 1 to 20 seconds / 100 mL.

[0541] In addition, the non-woven fabric sheet may have a thickness of 10 to 20 μm, but this is merely an example and is not limited thereto. A non-woven fabric sheet having a thickness outside the above range can also be adopted according to the permeability of the non-woven fabric sheet.

[0542] The non-woven fabric sheet can be bonded to the separation film component below the non-woven fabric sheet by lamination. Lamination can be performed in a temperature range of 100 to 150 °C. However, when lamination is performed at a temperature lower than 100 °C, the lamination effect is not achieved, and when lamination is performed at a temperature higher than 150 °C, there is a possibility that a part of the non-woven fabric melts.

[0543] Under the above conditions, the separation membrane according to one embodiment of the present invention joined by lamination has improved resistance to nail penetration compared to a separation membrane made of a conventional non-woven fabric sheet and also compared to a separation membrane having a layer containing inorganic particles formed on at least one surface of a film or a non-woven fabric sheet.

[0544] In the porous coating layer, the inorganic particles are filled and in contact with each other and are bound by the binder polymer, whereby an interstitial volume is formed between the inorganic particles, and the interstitial volume between the inorganic particles can become a void space to form pores.

[0545] As the inorganic particles used for forming the porous coating layer, inorganic particles, that is, inorganic particles in which oxidation and / or reduction reactions do not occur in the operating voltage range of the electrochemical element (for example, 0 to 5 V based on Li / Li + can be further added and used. In particular, when using inorganic particles having ion conductivity, the ion conductivity in the electrochemical element can be increased to improve the performance. Also, when using inorganic particles having a high dielectric constant as the inorganic particles, it can contribute to an increase in the dissociation degree of electrolyte salts in the liquid electrolyte, such as lithium salts, and improve the ion conductivity of the electrolyte.

[0546] For the reasons described above, the inorganic particles preferably include inorganic particles having a dielectric constant of 5 or more, preferably 10 or more, inorganic particles having lithium ion conductivity, or a mixture thereof.

[0547] Non-limiting examples of inorganic particles having a dielectric constant of 5 or more include BaTiO3, Pb(Zr,Ti)O3 (PZT), Pb 1-x La x Zr 1-y Ti y O3 (PLZT), PB(Mg 1 / 3 Nb 2 / 3)Examples include O3-PbTiO3 (PMN-PT), hafnia (HfO2), SrTiO3, SnO2, CeO2, MgO, NiO, CaO, ZnO, ZrO2, Y2O3, Al2O3, TiO2, SiC, or a mixture thereof.

[0548] In particular, the above-mentioned BaTiO3, Pb(Zr,Ti)O3 (PZT), Pb 1-x La x Zr 1-y Ti y O3 (PLZT), PB(Mg 1 / 3 Nb 2 / 3 )O3-PbTiO3 (PMN-PT) and inorganic particles such as hafnia (HfO2) not only exhibit a high dielectric constant characteristic with a dielectric constant of 100 or more, but also have piezoelectricity in which charges are generated and a potential difference is generated between both sides when a certain pressure is applied for tension or compression, thereby preventing internal short circuits from occurring at both electrodes due to external shocks and improving the safety of the electrochemical device. Further, when the above-mentioned high-dielectric-constant inorganic particles and inorganic particles having lithium-ion transfer ability are mixed, these synergistic effects are multiplied.

[0549] Inorganic particles having lithium-ion transfer ability refer to inorganic particles that contain lithium elements but do not store lithium and have a function of moving lithium ions. Inorganic particles having lithium-ion transfer ability can transfer and move lithium ions due to a kind of defect existing inside the particle structure, so that the lithium-ion conductivity in the battery is improved, and thereby the battery performance can be improved. Non-limiting examples of the inorganic particles having lithium-ion transfer ability include lithium phosphate (Li3PO4), lithium titanium phosphate (Li x Ti y (PO4)3, 0 < x < 2, 0 < y < 3), lithium aluminum titanium phosphate (Li x Al y Ti z(PO4)3, where 0 < x < 2, 0 < y < 1, 0 < z < 3, such as 14Li2O - 9Al2O3 - 38TiO2 - 39P2O5, (LiAlTiP) x O y series glass (0 < x < 4, 0 < y < 13), lithium lanthanum titanate (Li x La y TiO3, where 0 < x < 2, 0 < y < 3), Li 3.25 Ge 0.25 P 0.75 such as lithium germanium thiophosphate (Li x Ge y P z S w , where 0 < x < 4, 0 < y < 1, 0 < z < 1, 0 < w < 5), lithium nitride (Li x N y , where 0 < x < 4, 0 < y < 2), SiS2 series glass (Li x Si y S z , where 0 < x < 3, 0 < y < 2, 0 < z < 4), P2S5 series glass (Li x P y S z , where 0 < x < 3, 0 < y < 3, 0 < z < 7) or mixtures thereof, etc. can be mentioned.

[0550] There is no limit to the size of the inorganic particles in the porous coating layer, but for the formation of a coating layer with a uniform thickness and an appropriate porosity, it is preferably 0.001 - 10 μm. If it is less than 0.001 μm, the dispersibility of the inorganic particles decreases. If it exceeds 10 μm, the thickness of the porous coating layer increases, resulting in a decrease in mechanical properties and an overly large pore size, increasing the possibility of internal short - circuit during charging and discharging of the battery.

[0551] As the binder polymer for forming the porous coating layer, any one binder polymer selected from the group consisting of polyvinylidene fluoride - hexafluoropropylene, polyvinylidene fluoride - trichloroethylene, polymethyl methacrylate, polybutyl acrylate, polyacrylonitrile, polyvinyl pyrrolidone, polyvinyl acetate, ethylene vinyl acetate copolymer, polyethylene oxide, polyarylate, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl pullulan, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, cyanoethyl sucrose, pullulan and carboxymethyl cellulose, or a mixture of two or more of these can be used, but it is not limited thereto.

[0552] The composition ratio of the inorganic particles and the binder polymer used in the porous coating layer is preferably in the range of, for example, 50:50 to 99:1, more preferably 70:30 to 95:5. When the content of the inorganic particles relative to the binder polymer is less than 50 parts by weight, the content of the binder polymer increases, and the improvement of the thermal safety of the separation membrane may be reduced. Also, due to the reduction of the empty spaces formed between the inorganic particles, the pore size and porosity decrease, and the final battery performance may decrease. When the content of the inorganic particles exceeds 99 parts by weight, the content of the binder polymer is too small, and the peel resistance of the porous coating layer may be weakened. The thickness of the porous coating layer is not particularly limited, but preferably 0.01 to 20 μm. Also, the pore size and porosity are not particularly limited, but the pore size is preferably 0.001 to 10 μm, and the porosity is preferably 10 to 90%. The pore size and porosity mainly depend on the size of the inorganic particles. For example, when using inorganic particles with a particle size of 1 μm or less, the formed pores will also be about 1 μm or less. Such a pore structure is filled with the electrolyte injected later, and the filled electrolyte plays a role in ion transfer. When the pore size and porosity are less than 0.001 μm and 10%, it acts as a resistance layer, and when they exceed 10 μm and 90%, the mechanical properties may decrease.

[0553] The porous coating layer can be formed by dissolving or dispersing a binder polymer in a dispersion medium, adding inorganic particles to obtain a slurry for forming the porous coating layer, and coating and drying such a slurry on at least one surface of a substrate. As the dispersion medium, those having a solubility index similar to the binder polymer to be used and a low boiling point are preferable. This is to facilitate uniform mixing and subsequent removal of the dispersion medium. Non-limiting examples of the dispersion medium that can be used include acetone, tetrahydrofuran, methylene chloride, chloroform, dimethylformamide, N-methyl-2-pyrrolidone (NMP), cyclohexane, water, or a mixture thereof.

[0554] It is preferable to add inorganic particles to the dispersion in which the binder polymer is dispersed in a dispersion medium and then crush the inorganic particles. At this time, the crushing time is appropriately 1 hour to 20 hours, and the size of the crushed inorganic particles is preferably 0.001 to 10 μm as described above. As the crushing method, a normal method can be used, and particularly the ball mill method is preferable.

[0555] Thereafter, the binder polymer dispersion in which the inorganic particles are dispersed is coated and dried on at least one surface of the porous polymer substrate under humidity conditions of 10 to 80%. As the method for coating the dispersion on the porous polymer substrate, a normal coating method well known in the art can be used, and for example, various methods such as dip coating, die coating, roll coating, comma coating, or a mixed method thereof can be applied.

[0556] As components of the porous coating layer, in addition to the above-described inorganic particles and binder polymer, other additives such as a conductive material may be further included.

[0557] The separation membrane finally fabricated according to an embodiment of the present invention may have a thickness of 1 to 100 μm or 5 to 50 μm. If the thickness is less than 1 μm, the function of the separation membrane cannot be fully exerted, and the mechanical properties deteriorate. If it exceeds 100 μm, the characteristics of the battery may deteriorate during high-rate charge and discharge. Further, it may have a porosity of 40 to 60% and an air permeability of 150 to 300 seconds / 100 mL.

[0558] According to an embodiment of the present invention, the porous polymer substrate may use polyethylene or polypropylene. Also, in the porous coating layer, as the inorganic particles, a coating material of Al oxide or Si oxide system may be used.

[0559] When using the separation membrane according to an embodiment of the present invention, since the porous coating layers are provided on both sides of the porous polymer substrate, a uniform solid electrolyte interface layer can be formed by improving the impregnation performance with respect to the electrolyte, and an excellent air permeability can be ensured compared to the conventional single-sided inorganic-coated separation membrane. For example, it may be within 120 s / 100 cc. Also, even when inorganic porous coating layers are provided on both sides, a thickness at the level of the conventional single-sided inorganic-coated separation membrane can be realized. For example, it may be within 15.0 μm.

[0560] Also, when using the separation membrane according to an embodiment of the present invention, the stability of the separation membrane is improved, and heat resistance and compression resistance characteristics can be ensured. Specifically, heat resistance characteristics with a heat shrinkage characteristic of within 5% based on 180 °C can be ensured, and physical properties of a puncture strength of 550 gf or more can be ensured. When core deformation occurs during the cycle of a battery employing such a separation membrane, damage or penetration of the separation membrane at the step portion of the core can be prevented.

[0561] As the separation membrane, a porous polymer film, for example, a porous polymer film made of a polyolefin polymer such as a homopolymer of ethylene, a homopolymer of propylene, an ethylene / butene copolymer, an ethylene / hexene copolymer, an ethylene / methacrylate copolymer, etc., can be used alone or by laminating these. As another example, as the separation membrane, a normal porous nonwoven fabric, for example, a nonwoven fabric made of high melting point glass fibers, polyethylene terephthalate fibers, etc., can be used.

[0562] Hereinafter, the structure of the electrode assembly according to an embodiment of the present invention will be described in detail.

[0563] FIG. 11 is a cross-sectional view of a jelly roll type electrode assembly 80 in which the electrode 40 of the first embodiment is applied to a first electrode (positive electrode) and a second electrode (negative electrode), cut along the Y-axis direction (winding axis direction).

[0564] The electrode assembly 80 can be manufactured by the winding method described with reference to FIG. 2. For convenience of explanation, the protruding structures of the first plain part 43a and the second plain part 43b extending outside the separation membrane are shown in detail, and the illustration of the winding structure of the first electrode, the second electrode, and the separation membrane is omitted. The first plain part 43a protruding upward extends from the first electrode, and the second plain part 43b protruding downward extends from the second electrode.

[0565] A pattern in which the heights of the first plain part 43a and the second plain part 43b change is schematically shown. That is, the height of the plain part can change irregularly depending on the cutting position of the cross section. As an example, if the sides of the trapezoidal segments 61, 61' or the cutting groove 63 are cut, the height of the plain part in the cross section becomes lower than the height H of the segments 61, 61'. Therefore, it should be understood that the height of the plain part shown in the drawing showing the cross section of the electrode assembly corresponds to the average of the heights of the plain parts (H in FIGS. 7b and 8b) included in each winding turn.

[0566] Referring to FIG. 11, the first non-patterned 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.

[0567] The height (length in the Y-axis direction) of the second portion B3 is relatively lower than the height of the third portion B2. Therefore, it is possible to prevent a phenomenon in which the beading portion of the battery housing comes into contact with the second portion B3 during the process of being pressed near the second portion B3, resulting in an internal short circuit.

[0568] The second non-patterned portion 43b has the same structure as the first non-patterned portion 43a. In one variant form, the second non-patterned portion 43b may have a conventional electrode structure or an electrode structure of other embodiments (variant forms).

[0569] The end portions 81 of the first non-patterned portion 43a and the second non-patterned portion 43b can be bent from the radial direction of the electrode assembly 80, for example, from the outer peripheral side to the core side. At this time, the second portion B3 may not be substantially bent.

[0570] FIG. 12 is a cross-sectional view taken along the Y-axis direction (winding axis direction) of a jelly roll type electrode assembly 90 in which the electrode 45 of the second embodiment is applied to a first electrode (positive electrode) and a second electrode (negative electrode).

[0571] Referring to FIG. 12, the first non-patterned 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.

[0572] The height of the second portion B3 is relatively lower than the height of the third portion B2 and gradually or stepwise decreases from the core side toward the outer peripheral side. Therefore, it is possible to prevent a phenomenon in which the beading portion of the battery housing comes into contact with the second portion B3 during the process of being pressed near the second portion B3, resulting in an internal short circuit.

[0573] The second non-coated portion 43b has the same structure as the first non-coated portion 43a. In one variant, the second non-coated portion 43b may have a conventional electrode structure or the electrode structure of other embodiments (variants).

[0574] The ends 91 of the first non-coated portion 43a and the second non-coated portion 43b can be bent from the radial direction of the electrode assembly 90, for example, from the outer peripheral side to the core side. At this time, the outermost side 92 of the second portion B3 may not be substantially bent.

[0575] FIG. 13 is a cross-sectional view of a jelly roll type electrode assembly 100 in which any one of the electrodes 50, 60, 70 of the third to fifth embodiments (these variants) is applied to the first electrode (positive electrode) and the second electrode (negative electrode), cut along the Y-axis direction (winding axis direction).

[0576] Referring to FIG. 13, the non-coated 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.

[0577] The height of the first portion B1 is relatively lower than the height of the third portion B2. Also, in the third portion B2, the bending length of the non-coated portion 43a located innermost is the same as or shorter than the radial length R of the first portion B1. The bending length H corresponds to the distance from the point where the non-coated portion 43a is bent to the upper end of the non-coated portion 43a. In a variant, the bending length H can be smaller than the value obtained by adding the radial length R of the first portion B1 and 10% of the radius of the core 102.

[0578] Therefore, even if the third portion B2 is bent, 90% or more of the diameter of the core 102 of the electrode assembly 100 is open to the outside. The core 102 is a cavity at the center of the electrode assembly 100. If the core 102 is not blocked, there is no problem in the electrolyte injection process, and the efficiency of electrolyte injection is improved. Also, a welding jig can be inserted through the core 102 to easily perform the welding process between the current collector on the negative electrode (or positive electrode) side and the battery housing (or terminal).

[0579] The height of the second part B3 is relatively lower than the height of the third part B2. Therefore, it is possible to prevent a phenomenon in which the beading part and the second part B3 come into contact with each other and cause an internal short circuit during the process in which the beading part of the battery housing is pressed near the second part B3.

[0580] In a modified form, the height of the second part B3 may decrease gradually or stepwise, different from the illustration in FIG. 13. Further, in FIG. 13, the height of the third part B2 is equal in a part on the outer peripheral side, but the height of the third part B2 may increase gradually or stepwise from the boundary between the first part B1 and the third part B2 to the boundary between the third part B2 and the second part B3. When the third part B2 is divided into a plurality of segmented pieces, the section where the height of the plain part 43a changes corresponds to the height variable section of the segmented piece (circle 2 in FIG. 10a).

[0581] The second plain part 43b has the same structure as the first plain part 43a. In a modified form, the second plain part 43b may have a conventional electrode structure or an electrode structure of other embodiments (modified forms).

[0582] The end portions 101 of the first plain part 43a and the second plain part 43b may be bent from the radial direction of the electrode assembly 100, for example, from the outer peripheral side to the core side. At this time, the first part B1 and the second part B3 are not substantially bent.

[0583] When the third part B2 includes a plurality of segmented pieces, since the bending stress is relaxed, it is possible to prevent the plain part 43a near the bending point from being torn or abnormally deformed. Further, when the width and / or height and / or separation pitch of the segmented piece are adjusted within the numerical range of the above-described embodiment, the segmented pieces overlap multiple times to ensure sufficient welding strength while being bent toward the core side, and do not form a space (gap) in the bent surface area.

[0584] FIG. 14 is a cross-sectional view of an electrode assembly 110 according to still another embodiment of the present invention cut along the Y-axis direction (winding axis direction).

[0585] Referring to FIG. 14, the electrode assembly 110 has substantially the same configuration as the electrode assembly 100 of FIG. 13, except that the height of the second portion B3 is substantially the same as the outermost height of the third portion B2.

[0586] The second portion B3 may include a plurality of segmented slices. The configuration of the plurality of segmented slices is substantially the same as that of the fourth and fifth embodiments (modifications) regarding the electrodes.

[0587] 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 bending length H of the plain portion located innermost in 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 segmented slice omission section (circle 1 in FIG. 10a) without segmented slices. In a modification, the bending length H may be smaller than the value obtained by adding the radial length R of the first portion B1 and 10% of the radius of the core 112.

[0588] Therefore, even when the third portion B2 is bent, 90% or more of the diameter of the core 112 of the electrode assembly 110 is open to the outside. If the core 112 is not blocked, there is no problem in the electrolyte injection process, and the efficiency of electrolyte injection is improved. Also, a welding jig can be inserted through the core 112 to easily perform the welding process between the current collector on the negative electrode (or positive electrode) side and the battery housing (or terminal).

[0589] In a modification, the structure in which the height of the third portion B2 gradually or stepwise increases from the core side to the outer peripheral side may be extended to the second portion B3. In this case, the height of the plain portion 43a may gradually or stepwise increase from the boundary between the first portion B1 and the third portion B2 to the outermost surface of the electrode assembly 110.

[0590] The second plain portion 43b has the same structure as the first plain portion 43a. In a modification, the second plain portion 43b may have a conventional electrode structure or an electrode structure of other embodiments (modifications).

[0591] The ends 111 of the first landless part 43a and the second landless part 43b can be bent from the radial direction of the electrode assembly 110, for example, from the outer peripheral side to the core side. At this time, the first part B1 is not substantially bent.

[0592] When the third part B2 and the second part B3 include a plurality of divided segments, the bending stress is relaxed, so that it is possible to prevent the landless parts 43a and 43b near the bending point from being torn or abnormally deformed. Further, when the width and / or height and / or separation pitch of the divided segments are adjusted within the numerical range of the above-described embodiments, the divided segments are overlapped multiple times to such an extent that sufficient welding strength can be ensured while being bent toward the core side, and no space (gap) is formed in the bent surface region.

[0593] FIG. 15 is a cross-sectional view of an electrode assembly 120 according to still another embodiment of the present invention, taken along the Y-axis direction (winding axis direction).

[0594] Referring to FIG. 15, the electrode assembly 120 is different from the electrode assembly 100 of FIG. 13 only in that the height of the third part B2 has a pattern of gradually increasing or stepwise increasing and then decreasing, and other configurations are substantially the same. The radius section in which the height of the third part B2 changes can be regarded as a height variable section of the divided segments (circle 2 in FIG. 10a). Also in this case, the height variable section of the divided segments can be designed such that a stacked number uniform section in which the number of stacked divided segments is 10 or more appears in the bent surface region F formed while the third part B2 is bent, within the above-described preferred numerical range.

[0595] Such a change in the height of the third part B2 can be realized by adjusting the height of the stepped pattern (see FIG. 6) or the divided segments (see FIG. 7a or FIG. 8a) included in the third part B2.

[0596] In the electrode assembly 120, the height of the first portion B1 is relatively lower than the height of the third portion B2. Also, the bending length H of the plain portion located innermost in the third portion B2 is the same as or shorter than the radial length R of the first portion B1. The section corresponding to the first portion B1 corresponds to a section omission section without a segment (circle 1 in Fig. 10a). In a modified example, the bending length H can be smaller than the value obtained by adding the radial length R of the first portion B1 and 10% of the radius of the core 102.

[0597] Therefore, even when the third portion B2 is bent toward the core side, the core 122 of the electrode assembly 120 is opened to the outside by 90% or more of its diameter. If the core 122 is not blocked, there is no problem in the electrolyte injection process, and the efficiency of electrolyte injection is improved. Also, a welding jig can be inserted through the core 122, and the welding process between the current collector on the negative electrode (or positive electrode) side and the battery housing (or terminal) can be easily performed.

[0598] Also, 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, in the process of pressing the beading portion of the battery housing near the second portion B3, it is possible to prevent the phenomenon of internal short circuit occurring while the beading portion and the second portion B3 come into contact with each other. In a modified example, the height of the second portion B3 can gradually or stepwise decrease toward the outer peripheral side.

[0599] The second plain portion 43b has the same structure as the first plain portion 43a. In a modified example, the second plain portion 43b may have a conventional electrode structure or an electrode structure of other embodiments (modified forms).

[0600] The end portions 121 of the first plain portion 43a and the second plain portion 43b can be bent from the outer peripheral side to the core side of the electrode assembly 120. At this time, the first portion B1 and the second portion B3 are not substantially bent.

[0601] When the third part B2 includes a plurality of segmented pieces, the bending stress is relaxed, so that it is possible to prevent the plain portions 43a and 43b from being torn or abnormally deformed. Further, when the width and / or height and / or separation pitch of the segmented pieces are adjusted within the numerical ranges of the above-described embodiments, the segmented pieces are multiply overlapped to such an extent that sufficient welding strength can be ensured while being bent toward the core side, and no space (gap) is formed in the bent surface region.

[0602] FIG. 16 is a cross-sectional view of the electrode assembly 130 according to still another embodiment of the present invention, cut along the Y-axis direction (winding axis direction).

[0603] Referring to FIG. 16, the electrode assembly 130 is different from the electrode assembly 120 of FIG. 15 in that the height of the second part B3 has a pattern in which the height gradually or stepwise decreases from the boundary point between the second part B3 and the third part B2 toward the outermost surface of the electrode assembly 130, and other configurations are substantially the same.

[0604] Such a change in the height of the second part B3 can be realized by extending the stepped pattern (see FIG. 6) included in the third part B2 up to the second part B3 and gradually or stepwise decreasing the height of the pattern toward the outer peripheral side. Further, in other modified examples, the change in the height of the second part B3 can be realized by extending the segmented piece structure of the third part B2 up to the second part B3 and gradually or stepwise decreasing the height of the segmented pieces toward the outer peripheral side.

[0605] In the electrode assembly 130, the height of the first part B1 is relatively lower than the height of the third part B2. Further, the bending length H of the plain portion located innermost in 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 segmented piece omission section (circle 1 in FIG. 10a) without segmented pieces. In a modified example, the bending length H can be smaller than the value obtained by adding the radial length R of the first part B1 and 10% of the radius of the core 102.

[0606] Therefore, even if the third portion B2 is bent toward the core side, at least 90% of the diameter of the core 132 of the electrode assembly 130 is open to the outside. If the core 132 is not blocked, there is no problem in the electrolyte injection process, and the efficiency of electrolyte injection is improved. Further, a welding jig can be inserted through the core 132 to easily perform the welding process between the current collector on the negative electrode (or positive electrode) side and the battery housing (or terminal).

[0607] The second non-textured portion 43b has the same structure as the first non-textured portion 43a. In one variant form, the second non-textured portion 43b may have a conventional electrode structure or an electrode structure of other embodiments (variant forms).

[0608] The ends 131 of the first non-textured portion 43a and the second non-textured portion 43b can be bent from the outer peripheral side of the electrode assembly 130 toward the core side. At this time, the first portion B1 is not substantially bent.

[0609] When the third portion B2 and the second portion B3 include a plurality of segmented pieces, since the bending stress is relaxed, it is possible to prevent the non-textured portions 43a and 43b near the bending point from being torn or abnormally deformed. Further, when the width and / or height and / or separation pitch of the segmented pieces are adjusted within the numerical range of the above-described embodiments, the segmented pieces are overlapped multiple times to such an extent that sufficient welding strength can be ensured while being bent toward the core side, and no space (gap) is formed in the bent surface region.

[0610] On the one hand, in the above-described embodiments (modification forms), the ends of the first non-patterned portion 43a and the second non-patterned portion 43b can be bent from the core side to the outer peripheral side. In this case, the second portion B3 is designed as a segment-omitted section (circle 1 in FIG. 10a) without segments and preferably is not bent to the outer peripheral side. Also, the radial width of the second portion B3 can be the same as or larger than the length by which the outermost non-patterned portion (or segment) of the third portion B2 is bent. Thereby, when the outermost non-patterned portion (or segment) of the third portion B2 is bent to the outer peripheral side, the end of the bent portion does not protrude beyond the outer peripheral surface of the electrode assembly toward the inner surface of the battery housing. Also, the change pattern of the segment structure may be opposite to that of the above-described embodiments (modification forms). For example, the height of the segments can increase stepwise or gradually from the core side to the outer peripheral side. That is, by arranging a segment-omitted section (circle 1 in FIG. 10a), a segment height variable section (circle 2 in FIG. 10a), and a segment height uniform section (circle 3 in FIG. 10a) in order from the outer peripheral side to the core side of the electrode assembly, a stacked number uniform section in which the number of stacked segments in the bent surface region is 10 or more may appear within a preferable numerical range.

[0611] The structures of various electrode assemblies according to embodiments of the present invention are applicable to cylindrical batteries.

[0612] Preferably, the cylindrical battery can be a cylindrical battery having a form factor ratio (a value obtained by dividing the diameter of the cylindrical battery by the height, that is, a ratio of the height (H) to the diameter (Φ)) greater than about 0.4. Here, the form factor means a value indicating the diameter and height of the cylindrical battery.

[0613] Preferably, the diameter of the cylindrical battery can be 40 mm to 50 mm, and the height can be 60 mm to 130 mm. The form factor of the cylindrical battery according to one embodiment can be, for example, 46110, 4875, 48110, 4880, or 4680. In the numerical value indicating the form factor, the first two digits in front indicate the diameter of the battery, and the remaining digits indicate the height of the battery.

[0614] When applying an electrode assembly having a tabless structure to a cylindrical battery whose form factor ratio exceeds 0.4, the stress applied in the radial direction during bending of the plain portion is large, and the plain portion is likely to break. Further, when welding a current collector to the bent surface region of the plain portion, in order to sufficiently ensure the welding strength and reduce the resistance, the number of laminations of the plain portion in the bent surface region must be sufficiently increased. Such requirements can be achieved by the electrodes and electrode assemblies according to embodiments (modifications) of the present invention.

[0615] A battery according to an embodiment of the present invention can be a substantially cylindrical battery having a diameter of about 46 mm, a height of about 110 mm, and a form factor ratio of 0.418.

[0616] A battery according to another embodiment can be a substantially cylindrical battery having a diameter of about 48 mm, a height of about 75 mm, and a form factor ratio of 0.640.

[0617] A battery according to still another embodiment can be a substantially cylindrical battery having a diameter of about 48 mm, a height of about 110 mm, and a form factor ratio of 0.436.

[0618] A battery according to still another embodiment can be a substantially cylindrical battery having a diameter of about 48 mm, a height of about 80 mm, and a form factor ratio of 0.600.

[0619] A battery according to still another embodiment can be a substantially cylindrical battery having a diameter of about 46 mm, a height of about 80 mm, and a form factor ratio of 0.575.

[0620] Conventionally, batteries with a form factor ratio of about 0.4 or less have been used. That is, conventionally, for example, 1865 batteries, 2170 batteries, etc. have been used. In the case of an 1865 battery, its diameter is about 18 mm, its height is about 65 mm, and the form factor ratio is 0.277. In the case of a 2170 battery, the diameter is about 21 mm, the height is about 70 mm, and the form factor ratio is 0.300.

[0621] Hereinafter, a cylindrical battery according to an embodiment of the present invention will be described in detail.

[0622] FIG. 17 is a cross-sectional view of a cylindrical battery 140 according to an embodiment of the present invention cut along the Y-axis direction.

[0623] Referring to FIG. 17, a cylindrical battery 140 according to an embodiment of the present invention includes an electrode assembly 141 including a first electrode, a separator, and a second electrode, a battery housing 142 that houses the electrode assembly 141, and a sealing body 143 that seals an open end of the battery housing 142.

[0624] The battery housing 142 is a cylindrical container having an opening formed upward. The battery housing 142 is made of a conductive metal material such as aluminum, steel, or stainless steel. A nickel coating layer may be formed on the surface of the battery housing 142. The battery housing 142 houses the electrode assembly 141 in the inner space through the upper end opening, and also houses the electrolyte together.

[0625] The electrolyte may be a salt having a structure such as A + B - . Here, A + includes alkali metal cations such as Li + , Na + , K + , or ions composed of a combination 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 any one or more anions selected from the group consisting of.

[0626] Also, the electrolyte can be used by dissolving it in an organic solvent. As the organic solvent, propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, tetrahydrofuran, N-methyl-2-pyrrolidone (NMP), ethyl methyl carbonate (EMC), γ-butyrolactone, or a mixture thereof can be used.

[0627] The electrode assembly 141 may have a jelly-roll structure, but the present invention is not limited thereto. As shown in FIG. 2, the electrode assembly 141 can be manufactured by winding a laminate formed by laminating at least once in sequence a lower separator, a first electrode, an upper separator, and a second electrode around a winding shaft C.

[0628] The first electrode and the second electrode have different polarities. That is, if one has a positive polarity, the other has a negative polarity. At least one of the first electrode and the second electrode may have an electrode structure according to the above-described embodiment (modified form). Further, the other of the first electrode and the second electrode may have a conventional electrode structure or an electrode structure according to an embodiment (modified form). The number of electrode pairs included in the electrode assembly 141 is not limited to one and may be two or more.

[0629] From the upper and lower portions of the electrode assembly 141, a first non-patterned portion 146a of the first electrode and a second non-patterned portion 146b of the second electrode protrude, respectively. The first electrode has an electrode structure of the first embodiment (modified form). Therefore, the height of the second portion B3 of the first non-patterned portion 146a is lower than that of the non-patterned portions of the other portions. The second portion B3 is spaced apart from the inner peripheral surface of the battery housing 142, particularly the beading portion 147, by a predetermined distance. Therefore, since the second portion B3 of the first electrode does not contact the battery housing 142 electrically connected to the second electrode, an internal short circuit of the cylindrical battery 140 is prevented.

[0630] The second non-patterned portion 146b of the second electrode may have the same structure as the first non-patterned portion 146a. In other modified forms, the second non-patterned portion 146b may selectively have the structure of the non-patterned portion of the electrode according to the embodiment (modified form).

[0631] The sealing body 143 may include a cap 143a having a plate shape, a first gasket 143b that provides airtightness between the cap 143a and the battery housing 142 and has insulating properties, and a connection plate 143c electrically and mechanically coupled to the cap 143a.

[0632] The cap 143a is a component made of a conductive metal material and covers the upper end opening of the battery housing 142. The cap 143a is electrically connected to the first non-textured portion 146a of the first electrode and is electrically insulated from the battery housing 142 through the first gasket 143b. Therefore, the cap 143a can function as the first electrode terminal (e.g., the positive electrode) of the cylindrical battery 140.

[0633] The cap 143a is placed on the beading portion 147 formed on the battery housing 142 and fixed by the crimping portion 148. A first gasket 143b may be interposed between the cap 143a and the crimping portion 148 to ensure the airtightness of the battery housing 142 and the electrical insulation between the battery housing 142 and the cap 143a. The cap 143a may include a protruding portion 143d formed to protrude upward from the center thereof.

[0634] The battery housing 142 is electrically connected to the second non-textured portion 146b of the second electrode. Therefore, the battery housing 142 has the same polarity as the second electrode. If the second electrode has a negative polarity, the battery housing 142 also has a negative polarity.

[0635] The battery housing 142 includes a beading portion 147 and a crimping portion 148 at the upper end. The beading portion 147 is formed by pushing in around the outer peripheral surface of the battery housing 142. The beading portion 147 can function as a support portion on which the sealing body 143 is placed so that the electrode assembly 141 housed inside the battery housing 142 does not come out from the upper end opening of the battery housing 142.

[0636] The inner peripheral surface of the beading portion 147 is spaced apart from the second portion B3 of the first electrode by a predetermined distance. More specifically, the lower end of the inner peripheral surface of the beading portion 147 is spaced apart from the second portion B3 of the first electrode by a predetermined distance. Also, since the second portion B3 has a low height, it is not substantially affected even 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 the occurrence of partial deformation of the electrode assembly 141 and preventing an internal short circuit of the cylindrical battery 140.

[0637] Preferably, when the pushing depth of the beading portion 147 is D1 and the radial length from the inner peripheral surface of the battery housing 142 to the boundary point between the second portion B3 and the third portion B2 is D2, the relational expression "D1 ≦ D2" can be satisfied. In this case, when the battery housing 142 is pushed in to form the beading portion 147, damage to the second portion B3 is substantially prevented.

[0638] The crimping portion 148 is formed above the beading portion 147. The crimping portion 148 has a form that extends and is bent so as to wrap the outer peripheral surface of the cap 143a disposed on the beading portion 147 and a part of the upper surface of the cap 143a.

[0639] The cylindrical battery 140 may further include a first current collector 144 and / or a second current collector 145 and / or an insulator 146.

[0640] 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 metal material having conductivity such as aluminum, copper, steel, nickel, etc., and is electrically connected to the first non-coated portion 146a of the first electrode. The electrical connection can be made through 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 connection plate 143c, or may be directly coupled to the lower surface of the cap 143a. The connection between the lead 149 and other components can be made through welding.

[0641] Preferably, the first current collector 144 can be integrally formed with the lead 149. In this case, the lead 149 can have a long plate shape extending outward from near the center of the first current collector 144.

[0642] The first current collector 144 can be provided with a plurality of irregularities (not shown) formed radially on its lower surface. When the radial irregularities are provided, the first current collector 144 can be pressed to push the first non-coated portion 146a of the first electrode into the irregularities.

[0643] The first current collector 144 is coupled to the end of the first non-coated portion 146a. The coupling between the first non-coated 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 non-coated portion 146a can be performed with solder interposed therebetween. In this case, the solder can have a melting point lower than that of the first current collector 144 and the first non-coated portion 146a. Laser welding can be replaced with resistance welding, ultrasonic welding, spot welding, etc.

[0644] A second current collector 145 can be coupled to the lower surface of the electrode assembly 141. One surface of the second current collector 145 can be coupled to the second non-coated portion 146b by welding, and the other surface can be coupled to the inner bottom surface of the battery housing 142 by welding. The coupling structure between the second current collector 145 and the second non-coated portion 146b can be substantially the same as the coupling structure between the first current collector 144 and the first non-coated portion 146a.

[0645] The non-coated portions 146a and 146b are not limited to the illustrated structures. Therefore, the non-coated portions 146a and 146b may selectively have not only the structure of the conventional non-coated portion but also the structure of the non-coated portion of the electrode according to the embodiment (deformed form).

[0646] The insulator 146 can cover the first current collector 144. By covering the first current collector 144 on the upper surface of the first current collector 144, direct contact between the first current collector 144 and the inner peripheral surface of the battery housing 142 can be prevented.

[0647] The insulator 146 is provided with a lead hole 151 so that a lead 149 extending upward from the first current collector 144 can be drawn out. The lead 149 is drawn out upward through the lead hole 151 and is coupled to the lower surface of the connection plate 143c or the lower surface of the cap 143a.

[0648] The peripheral region of the insulator 146 is interposed between the first current collector 144 and the beading portion 147, and can fix the combined body of the electrode assembly 141 and the first current collector 144. Thereby, the movement of the combined body of 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.

[0649] The insulator 146 can be made of an insulating polymer resin. As an example, the insulator 146 can be made of polyethylene, polypropylene, polyimide, or polybutylene terephthalate.

[0650] The battery housing 142 may further include a vent portion 152 formed on its lower surface. The vent portion 152 corresponds to a region having a thickness thinner than that of the peripheral region on the lower surface of the battery housing 142. The vent portion 152 is structurally weaker than the peripheral region. Therefore, if an abnormality occurs in the cylindrical battery 140 and the internal pressure increases above a certain level, the vent portion 152 may rupture and the gas generated inside the battery housing 142 can be discharged to the outside. The internal pressure at which the vent portion 152 ruptures is about 15 kgf / cm 2 ~35 kgf / cm 2 and can be.

[0651] The vent portion 152 can be formed continuously or discontinuously while drawing a circle on the lower surface of the battery housing 142. As a modified example, the vent portion 152 can be formed in a straight line pattern or other patterns other than that.

[0652] FIG. 18 is a cross-sectional view of a cylindrical battery 150 cut along the Y-axis direction according to another embodiment of the present invention.

[0653] Referring to FIG. 18, the cylindrical battery 150 is substantially the same in other configurations as the cylindrical battery 140 in FIG. 17, except that the electrode structure of the second embodiment (deformed form) is adopted for the first non-coated portion 146a of the first electrode.

[0654] Referring to FIG. 18, the first non-coated 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 peripheral surface of the battery housing 142. Preferably, the virtual line connecting the uppermost ends of the second portion B3 may have the same or a similar shape as the inner peripheral surface of the beading portion 147.

[0655] The second portion B3 forms an inclined surface. Therefore, when the battery housing 142 is pushed in to form the beading portion 147, it is possible to prevent the second portion B3 from being compressed and damaged by the beading portion 147. In addition, it is possible to suppress the phenomenon that the second portion B3 comes into contact with the battery housing 142 of the opposite polarity and causes an internal short circuit.

[0656] Other configurations of the cylindrical battery 150 are substantially the same as those of the above-described embodiment (deformed form).

[0657] The non-coated portions 146a and 146b are not limited to the illustrated structures. Therefore, the non-coated portions 146a and 146b may selectively have the structures of the non-coated portions of the electrodes according to the conventional non-coated portion structures as well as the embodiments (deformed forms).

[0658] FIG. 19 is a cross-sectional view of a cylindrical battery 160 cut along the Y-axis direction according to still another embodiment of the present invention.

[0659] Referring to FIG. 19, the cylindrical battery 160 has a structure in which the lead 149 connected to the first current collector 144 passes through the lead hole 151 of the insulator 146 and is directly connected to the cap 143a of the sealing body 143, and the other configurations are substantially the same except that the insulator 146 and the first current collector 144 are in close contact with the lower surface of the cap 143a, compared with the cylindrical batteries 140 and 150 described above.

[0660] 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 can be the same as or larger than the outermost diameter of the third portion B2.

[0661] Specifically, the minimum inner diameter of the battery housing 142 may correspond to the inner diameter of the battery housing 142 at the position where the beading portion 147 is formed. At this time, the outermost diameter of the first current collector 144 and the third portion B2 is smaller than the inner diameter of the battery housing 142 at the position where the beading portion 147 is formed. Also, the diameter of the first current collector 144 can be the same as or larger than the outermost diameter of the third portion B2. The peripheral region of the insulator 146 is interposed between the second portion B3 and the beading portion 147 in a state of being bent downward, and the combined body of the electrode assembly 141 and the first current collector 144 can be fixed.

[0662] 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 bent together corresponding to the bent shape of the beading portion 147. The insulator 146 can insulate the second portion B3 from the inner peripheral surface of the beading portion 147 and at the same time insulate the first current collector 144 from the inner peripheral surface of the beading portion 147.

[0663] 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. At this time, the pushing depth D1 of the beading portion 147 is smaller 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 thereto may be positioned higher than the lower end of the beading portion 147. The lower end of the beading portion 147 means the bending point B between the portion of the battery housing 142 where the electrode assembly 141 is accommodated and the beading portion 147.

[0664] Since the first portion B1 and the third portion B2 occupy the radially inner space of the beading portion 147, the empty space between the electrode assembly 141 and the cap 143a is minimized. Also, the connection plate 143c that was located in the empty space between the electrode assembly 141 and the cap 143a is omitted. Therefore, the lead 149 of the first current collector 144 can be directly coupled to the lower surface of the cap 143a. According to such a structure, the empty space in the battery is reduced, and the energy density can be maximized by only the reduced empty space.

[0665] 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 non-textured portion 146a and the second non-textured portion 146b, respectively, in the same manner as in the above-described embodiment.

[0666] The non-textured portions 146a and 146b are not limited to only the illustrated structure. Therefore, the non-textured portions 146a and 146b may selectively have not only the structure of the conventional non-textured portion but also the structure of the non-textured portion of the electrode according to the embodiment (deformed form).

[0667] FIG. 20 is a cross-sectional view of a cylindrical battery 170 according to still another embodiment of the present invention, cut along the Y-axis direction.

[0668] Referring to FIG. 20, the cylindrical battery 170 has substantially the same structure of the electrode assembly as the cylindrical battery 140 shown in FIG. 17, and is different in that other structures except for the electrode assembly are changed.

[0669] Specifically, the cylindrical battery 170 includes a battery housing 171 through which a terminal 172 is penetratingly provided. The terminal 172 is attached through a through hole formed in a closing surface (the upper surface in the drawing) of the battery housing 171. The terminal 172 is riveted to the through hole of the battery housing 171 with a second gasket 173 made of an insulating material interposed therebetween. The terminal 172 is exposed outward in the direction opposite to the gravitational direction.

[0670] The terminal 172 includes a terminal exposed portion 172a and a terminal insertion portion 172b. The terminal exposed portion 172a is exposed outside the closing surface of the battery housing 171. The terminal exposed portion 172a may be located at a substantially central portion of the closing surface of the battery housing 171. The maximum diameter of the terminal exposed portion 172a may be formed to be even larger than the maximum diameter of the through hole formed in the battery housing 171. The terminal insertion portion 172b may penetrate through a substantially central portion of the closing surface of the battery housing 171 and be electrically connected to the first non-coated portion 146a of the first electrode. The periphery of the bottom of the terminal insertion portion 172b may be riveted to the inner surface of the battery housing 171. That is, the periphery of the bottom of the terminal insertion portion 172b may have a form bent toward the inner surface of the battery housing 171. A flat portion 172c is included inside the periphery of the bottom 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 of the battery housing 171.

[0671] The flat portion 172c of the terminal insertion portion 172b may be welded to the central portion of the first current collector 144 connected to the first non-coated portion 146a of the first electrode. As the welding method, laser welding is preferable, but other welding methods such as ultrasonic welding can be substituted.

[0672] 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 edge portion of the electrode assembly 141. Thereby, it is possible to prevent the second portion B3 of the electrode assembly 141 from contacting the inner surface of the battery housing 171 having an opposite polarity and causing a short circuit.

[0673] The thickness of the insulator 174 corresponds to or is slightly larger 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 may contact the upper surface of the first current collector 144 and the inner surface of the closing portion of the battery housing 171.

[0674] The terminal insertion portion 172b of the terminal 172 may be welded to the first current collector 144 through the through hole of the insulator 174. The diameter of the through hole formed in the insulator 174 may be larger than the diameter of the rivet 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.

[0675] The second gasket 173 is interposed between the battery housing 171 and the terminal 172 to prevent the battery housing 171 and the terminal 172 having opposite polarities from being in electrical contact. Thereby, the upper surface of the battery housing 171 having a substantially flat shape can function as the second electrode terminal (for example, the negative electrode) of the cylindrical battery 170.

[0676] The second gasket 173 includes a gasket exposed portion 173a and a gasket insertion 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 insertion portion 173b is interposed between the terminal insertion portion 172b of the terminal 172 and the battery housing 171. The gasket insertion portion 173b can be deformed together during riveting of the terminal insertion portion 172b and be in close contact with the inner surface of the battery housing 171. The second gasket 173 may be made of, for example, an insulating polymer resin.

[0677] The gasket exposed portion 173a of the second gasket 173 may have a form that extends to cover the outer peripheral surface of the terminal exposed portion 172a of the terminal 172. When the second gasket 173 covers the outer peripheral surface of the terminal 172, it is possible to prevent a short circuit from occurring during the process of coupling an electrical connection component such as a bus bar to the upper surface of the battery housing 171 and / or the terminal 172. Although not shown, the gasket exposed portion 173a may have a form that extends to cover not only the outer peripheral surface of the terminal exposed portion 172a but also a part of the upper surface.

[0678] When the second gasket 173 is made of a polymer resin, the second gasket 173 can be coupled to the battery housing 171 and the terminal 172 by thermal fusion. In this case, the airtightness at the coupling interface between the second gasket 173 and the terminal 172 and at the coupling 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 has a form that extends to the upper surface of the terminal exposed portion 172a, the terminal 172 may be integrally coupled to the second gasket 173 by insert injection molding.

[0679] On the upper surface of the battery housing 171, another region 175 excluding the regions occupied by the terminal 172 and the second gasket 173 corresponds to a second electrode terminal having a polarity opposite to that of the terminal 172.

[0680] 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, nickel, etc., and is electrically connected to the second non-coated portion 146b of the second electrode.

[0681] Preferably, the second current collector 176 is electrically connected to the battery housing 171. Therefore, at least a part of the peripheral portion of the second current collector 176 can be interposed and fixed between the inner surface of the battery housing 171 and the first gasket 178b. As an example, at least a part of the peripheral portion of the second current collector 176 can be fixed to the beading portion 180 by welding while being supported by the lower end surface of the beading portion 180 formed at the lower end of the battery housing 171. In a modified example, at least a part of the peripheral portion of the second current collector 176 can be directly welded to the inner wall surface of the battery housing 171.

[0682] The second current collector 176 may include a plurality of irregularities (not shown) radially formed on the surface facing the second plain portion 146b. When the irregularities are formed, the second current collector 176 can be pressed to press the second plain portion 146b into the irregularities.

[0683] Preferably, the second current collector 176 and the end of the second plain portion 146b can be joined by welding, for example, laser welding. Also, the welding portion between the second current collector 176 and the second plain portion 146b can be separated by a predetermined distance toward the core C side with respect to the inner peripheral surface of the beading portion 180.

[0684] The sealing body 178 that seals the lower open end of the battery housing 171 includes a cap 178a having a plate shape and a first gasket 178b. The first gasket 178b electrically separates the cap 178a and the battery housing 171. The crimping portion 181 fixes 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 (modified form). The lower surface of the cap 178a can be located above the lower end of the crimping portion 181. In this case, a space is formed below the cap 178a and venting is smoothly performed. In particular, this is useful when the cylindrical battery 170 is installed such that the crimping portion 181 faces the direction of gravity.

[0685] 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 has no electrical polarity. The seal 178 seals the open end at the bottom of the battery housing 171 and mainly functions to discharge gas when the internal pressure of the battery 170 increases above the critical value. The critical value of the internal pressure is 15 kgf / cm 2 ~35 kgf / cm 2 is.

[0686] Preferably, the terminal 172 electrically connected to the first non-textured portion 146a of the first electrode is used as the first electrode terminal. Also, among the upper surface of the battery housing 171 electrically connected to the second non-textured portion 146b of the second electrode through the second current collector 176, the portion 175 excluding the terminal 172 is used as the second electrode terminal having the opposite polarity to the first electrode terminal. In this way, when the two electrode terminals are located at the upper part of the cylindrical battery 170, it is possible to arrange electrical connection components such as bus bars only on one side of the cylindrical battery 170. This can lead to the simplification of the battery pack structure and the improvement of the energy density. In addition, since the portion 175 used as the second electrode terminal has a substantially flat shape, a sufficient connection area can be secured to connect electrical connection components such as bus bars. Thereby, the cylindrical battery 170 can reduce the resistance at the joint portion of the electrical connection components to a preferable level.

[0687] On the other hand, the structure of the electrode assembly 141 and the structure of the non-textured portion are not limited to those shown, and can be replaced with the structures of the above-described embodiments (deformed forms).

[0688] FIG. 21 is a cross-sectional view of a cylindrical battery 180 cut along the Y-axis direction according to still another embodiment of the present invention.

[0689] Referring to FIG. 21, the cylindrical battery 180 has a structure of the electrode assembly 141 that is substantially the same as that of the cylindrical battery 150 shown in FIG. 18, and other configurations except for the electrode assembly 141 are substantially the same as those of the cylindrical battery 170 shown in FIG. 20.

[0690] Therefore, the configurations of the embodiments (modified forms) of the cylindrical batteries 150 and 170 can be similarly applied to the cylindrical battery 180.

[0691] Also, the structure of the electrode assembly 141 and the structure of the plain portion are not limited to those shown, and can be replaced with the structures of the above-described embodiments (modified forms).

[0692] FIG. 22 is a cross-sectional view of a cylindrical battery 190 according to still another embodiment of the present invention, cut along the Y-axis direction.

[0693] Referring to FIG. 22, the cylindrical battery 190 includes the electrode assembly 110 shown in FIG. 14, and other configurations except for the electrode assembly 110 are substantially the same as those of the cylindrical battery 140 shown in FIG. 17. Therefore, the configurations described with reference to FIGS. 14 and 17 can be substantially similarly applied in this embodiment.

[0694] Referring to FIGS. 10a and 22, the first plain portion 146a and the second plain portion 146b of the electrode assembly 110 form a bending surface region F while being bent from the radial direction of the electrode assembly 110, for example, from the outer peripheral side to the core side.

[0695] The first portion B1 is lower in height than the other portions and corresponds to the section omission section a1 where there is no section, so it is not bent toward the core side.

[0696] Preferably, the bending surface region F may include a section omission section a1, a section height variable section a2, and a section height uniform section a3 from the core side to the outer peripheral side.

[0697] As shown in FIGS. 10c, 10d, and 10e, the bent surface region F includes a layer number uniform region b1 adjacent to the segment omission section a1 and having 10 or more layers of segments stacked therein.

[0698] The bent surface region F may also include a layer number decreasing region b2 adjacent to the outer periphery of the electrode assembly 110 and having the number of segments stacked decreasing toward the outer peripheral side. Preferably, the layer number uniform region b1 can be set as a welding target region.

[0699] In the bent surface region F, the preferred numerical ranges of the ratio (a2 / c) of the height variable section a2 to the radius region (c) including the segments, the ratio (b1 / c) of the layer number uniform region b1 to the radius region (c) including the segments, and the ratio of the area of the layer number uniform region b1 to the area of the bent surface region F have been described above, and repeated explanations are omitted.

[0700] The first current collector 144 can be laser welded to the bent surface region F of the first plain portion 146a, and the second current collector 145 can be laser welded to the bent surface region F of the second plain portion 146b. The welding method can be replaced with ultrasonic welding, resistance welding, spot welding, etc.

[0701] Preferably, 50% or more of the area of the welding regions W of the first current collector 144 and the second current collector 145 can overlap with the layer number uniform region b1 of the bent surface region F. Optionally, the remaining area of the welding region W can overlap with the layer number decreasing region b2 of the bent surface region F. In terms of high welding strength, low resistance at the welding interface, and prevention of damage to the separator and the active material layer, it is more preferable that the entire welding region W overlaps with the layer number uniform region b1.

[0702] Preferably, in the layer number uniform region b1 overlapping with the welding region W, and optionally in the layer number decreasing region b2, the number of segments stacked can be 10 to 35.

[0703] Alternatively, when the number of laminations of the segmented section in the lamination number reduction section b2 that overlaps with the welding region W is less than 10, the laser output for welding the lamination number reduction section b2 can be reduced compared to the laser output for welding the lamination number uniform section b1. That is, when the welding region W overlaps with the lamination number uniform section b1 and the lamination number reduction section b2 simultaneously, the output of the laser can be changed according to the number of laminations of the segmented section. In this case, the welding strength of the lamination number uniform section b1 can be greater than the welding strength of the lamination number reduction section b2.

[0704] In the bent surface region F formed at the upper and lower portions of the electrode assembly 110, the radial lengths of the segmented section omission section a1 and / or the segmented section height variable section a2 and / or the segmented section height uniform section a3 can be the same or different.

[0705] The height of the first portion B1 of the electrode assembly 110 is relatively lower than that of the other portions. Also, as shown in FIG. 14, the bending length H of the plain portion located innermost in the third portion B2 is smaller than the value obtained by adding the radial length R of the first portion B1 and 10% of the radius of the core 112.

[0706] Therefore, even when the first plain portion 146a is bent toward the core side, 90% or more of the diameter of the core 112 of the electrode assembly 110 can be opened to the outside. If the core 112 is not blocked, there is no problem in the electrolyte injection process, and the efficiency of electrolyte injection is improved. Also, a welding jig can be inserted through the core 112 to easily perform the welding process between the second current collector 145 and the battery housing 142.

[0707] When the plain portions 146a and 146b have a segmented structure, if the width and / or height and / or separation pitch of the segmented sections are adjusted to satisfy the numerical ranges of the above-described embodiments, when the segmented sections are bent, the segmented sections overlap multiple times to such an extent that sufficient welding strength can be ensured, and no space (gap) is formed in the bent surface region F.

[0708] Preferably, the first current collector 144 and the second current collector 145 may have an outer diameter that covers the ends of the slit pieces (see 61 and 61' in FIG. 10f) bent at the last winding turn of the height uniform section a3 of the first electrode and the second electrode. In this case, welding is possible with the slit pieces forming the bent surface region F pressed uniformly by the current collectors, and the tight stacked state of the slit pieces can be maintained even after welding. The tight stacked state means a state where there is substantially no gap between the slit pieces, as shown in FIG. 10a. The tight stacked state contributes to reducing the resistance of the cylindrical battery 190 to a level suitable for rapid charging (for example, 4 mΩ) or less.

[0709] The structure of the plain portions 146a and 146b may be changed to the structure according to the above-described embodiment (deformed form). Also, the application of the structure of the conventional plain portion to either one of the plain portions 146a and 146b is not restricted.

[0710] FIG. 23 is a cross-sectional view of a cylindrical battery 200 according to still another embodiment of the present invention, cut along the Y-axis direction.

[0711] Referring to FIG. 23, the cylindrical battery 200 includes the electrode assembly 110 shown in FIG. 14, and the other configurations except for the electrode assembly 110 are substantially the same as those of the cylindrical battery 180 shown in FIG. 21. Therefore, the configurations described with reference to FIGS. 14 and 21 can be applied substantially in the same manner also in this embodiment.

[0712] Referring to FIGS. 10a and 23, the first plain portion 146a and the second plain portion 146b of the electrode assembly 110 form a bent surface region F while being bent from the radial direction of the electrode assembly 110, for example, from the outer peripheral side to the core side.

[0713] The first portion B1 is lower in height than the other portions and corresponds to the slit omission section a1 where no slit pieces exist, so it is not bent toward the core side.

[0714] Preferably, the bent surface region F may include a segment omission section a1, a segment height variable section a2, and a segment height uniform section a3 from the core side to the outer peripheral side.

[0715] As shown in FIGS. 10c, 10d, and 10e, the bent surface region F includes a lamination number uniform section b1 adjacent to the segment omission section a1 where the number of laminated segments is 10 or more.

[0716] The bent surface region F may also include a lamination number decreasing section b2 adjacent to the outer periphery of the electrode assembly 110 where the number of laminated segments decreases toward the outer peripheral side. Preferably, the lamination number uniform section b1 can be set as a welding target region.

[0717] In the bent surface region F, the preferred numerical ranges of the ratio (a2 / c) of the height variable section a2 to the radius region (c) including the segments, the ratio (b1 / c) of the lamination number uniform section b1 to the radius region (c) including the segments, and the ratio of the area of the lamination number uniform section b1 to the area of the bent surface region F have been described above, so repeated explanations are omitted.

[0718] The first current collector 144 may be laser welded to the bent surface region F of the first plain portion 146a, and the second current collector 176 may be laser welded to the bent surface region F of the second plain portion 146b. The welding method can be replaced by ultrasonic welding, resistance welding, spot welding, etc. The welding region W between the second current collector 176 and the second plain portion 146b can be separated from the inner surface of the beading portion 180 by a predetermined distance.

[0719] Preferably, 50% or more of the regions of the welding regions W of the first current collector 144 and the second current collector 176 may overlap with the lamination number uniform section b1 of the bent surface region F. Optionally, the remaining regions of the welding region W may overlap with the lamination number decreasing section b2 of the bent surface region F. In terms of high welding strength, low resistance at the welding interface, and prevention of damage to the separation membrane and the active material layer, it is more preferable that the entire we...

Claims

1. An electrode assembly in which a first electrode, a second electrode, and a separation membrane interposed between the first electrode and the second electrode are wound around a winding shaft to define a core and an outer peripheral surface, 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 the active material layer, the first plain portion includes a slit section divided into a plurality of independently bendable slit pieces by a plurality of cutting grooves provided along the winding direction, the slit section includes a plurality of slit piece groups arranged at intervals between groups along the winding direction, one end face of the electrode assembly includes a plurality of slit piece alignment portions in which the plurality of slit piece groups are aligned along the radial direction, and an electrolyte impregnation portion in which an end portion of the first active material portion is exposed from between the winding turns of the separation membrane between adjacent slit piece alignment portions in the circumferential direction, the slit pieces included in the slit piece alignment portion are bent toward the core to form a bent surface region, an end portion of the separation membrane is separated within a preset distance from a reference line extending in the winding shaft direction along a position corresponding to the plurality of cutting grooves, the preset distance is 30% of the minimum height of the slit piece forming the bent surface region, the electrode assembly.

2. The electrode assembly according to claim 1, wherein the bent surface region is fan-shaped.

3. The electrode assembly according to claim 2, wherein the width in the winding direction of each slit piece group arranged in the bent surface region increases stepwise or gradually from the core side toward the outer peripheral side.

4. The electrode assembly according to claim 2, wherein the number of slit pieces included in each slit piece group arranged in the bent surface region increases gradually or stepwise from the core side toward the outer peripheral side.

5. The electrode assembly according to claim 1, wherein one or more selected from the width in the winding direction, the height in the winding shaft direction, the lower inner angle, and the separation pitch in the winding direction of the slit pieces included in the same slit piece group are the same.

6. The slit pieces included in the slit piece group located in the first winding turn are smaller in one or more selected from the width in the winding direction, the height in the winding shaft direction, the lower inner angle, and the separation pitch in the winding direction than the slit pieces included in the slit piece group located in the second winding turn located outside the first winding turn, the electrode assembly according to claim 1.

7. One or more selected from the width in the winding direction, the height in the winding axis direction, the lower inner angle, and the separation pitch in the winding direction of the segments included in the segment groups located at different winding turns gradually or stepwise increase as the radius of the winding turn increases, The electrode assembly according to claim 1.

8. The electrode assembly according to claim 1, wherein the bent surface region has a shape of a quadrilateral, a trapezoid, or a parallelogram.

9. The electrode assembly according to claim 1, wherein the bent surface region and the electrolyte impregnated portion extend radially with respect to the core.

10. When a line connecting the center of the core and the geometric center of a figure approximately corresponding to the bent surface region is defined as an angle measurement line, the angles between the angle measurement lines of adjacent bent surface regions in the circumferential direction are substantially equal, The electrode assembly according to claim 1.

11. The electrode assembly according to claim 10, wherein the angle is substantially 30°, 40°, 45°, 60°, 72°, 90°, 120°, or 180°.

12. At least a part of the segment group included in the segment alignment portion is in a state of rotating clockwise or counterclockwise with respect to the winding axis as the radius of the winding turn increases, The electrode assembly according to claim 1.

13. The electrode assembly according to claim 12, wherein the amount of rotation of the segment group in a state of rotating clockwise or counterclockwise with respect to the winding axis increases as the radius of the winding turn increases.

14. Further comprising an insulating layer covering a boundary region between the first plain portion and the active material layer along the winding direction, A gap is provided between the insulating layer and the cutting groove, The electrode assembly according to claim 1.

15. The electrode assembly according to claim 14, wherein the gap varies along the winding direction.

16. In a predetermined region of the first electrode, the gap increases or decreases more than in other regions, The electrode assembly according to claim 15.

17. In a predetermined region of the first electrode, the gap gradually or stepwise increases along a direction parallel to the winding direction, The electrode assembly according to claim 15.

18. The electrode assembly according to claim 14, wherein the gap is 0.2 mm to 4 mm.

19. The electrode assembly according to claim 14, wherein the insulating layer is exposed outside the separator along the winding axis direction.

20. The electrode assembly according to claim 15, wherein the insulating layer is thinner than the active material layer and is disposed separately from the separator membrane.

21. The sliced element alignment section includes a height variable section where the height of the sliced elements gradually increases from the core side to the outer peripheral side of the electrode assembly from the first height h １ to the (N - 1)-th height h Ｎ－１ (N is a natural number of 3 or more), and a height uniform section maintained uniformly at the N-th height h Ｎ (greater than h Ｎ－１ ), the electrode assembly according to claim 1.

22. Height h ｋ When defining the starting radius r of the winding turn including the segmented slice having (k is a natural number from 1 to N), ｋ the core of the electrode assembly is such that when defined as r, ｋ The electrode assembly according to claim 21, wherein 90% or more of the diameter is not blocked by the bent portion of the segmented slice located at r.

23. Height h ｋ Let r be the start 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 that 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 0.90 to 1) The electrode assembly according to claim 21, which satisfies

24. When the number of separators intersecting with an imaginary line parallel to the winding axis direction at an arbitrary radial position in the bent surface region is defined as the number of stacked separators at the corresponding radial position with reference to the center of the core of the electrode assembly, the bent surface region includes a stacked number uniform region where the number of stacked separators is uniform from the core side toward the outer peripheral side, and a stacked number decreasing region located outside the stacked number uniform region, where the number of stacked separators decreases toward the outer peripheral side. The electrode assembly according to claim 24.

25. The electrode assembly according to claim 25, wherein the number of stacked separators in the stacked number uniform region is 10 to 35.

26. The electrode assembly according to claim 25, wherein the first electrode is a positive electrode, and the stacked thickness of the separators in the stacked number uniform region is 100 μm to 875 μm.

27. The electrode assembly according to claim 25, wherein the first electrode is a negative electrode, and the stacked thickness of the separators in the stacked number uniform region is 50 μm to 700 μm.

28. 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 the active material layer.

29. The second plain portion includes a slitting section divided into a plurality of independently bendable slitting pieces by a plurality of cutting grooves provided along the winding direction. The slitting section of the second plain portion includes a plurality of slitting piece groups arranged with an inter-group separation interval along the winding direction. The other end face of the electrode assembly includes a plurality of slitting piece alignment portions where the plurality of slitting piece groups of the second plain portion are aligned along the radial direction, and an electrolyte impregnation portion where an end portion of the second active material portion is exposed from between the winding turns of the separator membrane between the slitting piece alignment portions of the second plain portion adjacent in the circumferential direction. ​ The sliced segments included in the sliced segment alignment portion of the second non-coated portion are bent toward the core to form a bent surface region. The end portion of the separation membrane is separated within a preset distance from a reference line extending in the winding axis direction along positions corresponding to the plurality of cutting grooves of the second non-coated portion. The preset distance is 30% of the minimum height of the sliced segments of the second non-coated portion that form the bent surface region. The electrode assembly according to claim 1.

30. An electrode assembly in which a first electrode, a second electrode, and a separation membrane interposed between the first electrode and the second electrode are wound around a winding axis to define a core and an outer peripheral surface. The first electrode includes a first active material portion coated with an active material layer along the winding direction and a first non-coated portion not coated with an active material layer. The first non-coated portion includes a sliced segment section divided into a plurality of independently bendable sliced segments by a plurality of cutting grooves provided along the winding direction. The sliced segment section includes a plurality of sliced segment groups arranged with an inter-group separation interval along the winding direction. One end surface of the electrode assembly includes a plurality of sliced segment alignment portions in which the plurality of sliced segment groups are aligned along the radial direction, and an electrolyte impregnation portion in which an end portion of the first active material portion is exposed from between turns of the winding of the separation membrane between adjacent sliced segment alignment portions in the circumferential direction. The sliced segments included in the sliced segment alignment portion are bent toward the core to form a bent surface region. The end portion of the separation membrane is separated within a preset distance from a reference line extending in the winding axis direction along positions corresponding to the plurality of cutting grooves. The preset distance is 30% of the minimum height of the sliced segments that form the bent surface region. An electrode assembly, A battery housing that houses the electrode assembly and is electrically connected to one of the first electrode and the second electrode to have a first polarity. A sealing body that seals an open end of the battery housing. A battery including a terminal that is electrically connected to the other of the first electrode and the second electrode and has a second polarity with its surface exposed to the outside.

31. A beading portion formed by pushing a peripheral edge region of an open end of the battery housing into the inside of the battery housing. A current collector electrically coupled to the bent surface region. The battery according to claim 30, further comprising an insulator covering the current collector and having a periphery fixed with an inner peripheral surface of the beading portion interposed therebetween and the current collector.

32. A cavity is provided in the core of the electrode assembly, The battery according to claim 30, wherein the cavity is open to the outside without being blocked by the bent surface region.

33. The sealing body includes a cap that seals an open end of the battery housing and a gasket that wraps around a periphery of the cap and is crimped to an upper end portion of the battery housing, The battery according to claim 30, wherein the terminal having the second polarity is the cap.

34. The battery according to claim 30, further comprising a current collector that is electrically connected to a non-textured portion of the second electrode having the first polarity and at least a part of the periphery of which is coupled to a side wall of the battery housing. The sealing body includes a cap without a polarity and a gasket that wraps around a periphery of the cap and is crimped to an upper end portion of the battery housing, The battery housing is insulatingly attached to a through hole formed in a central portion of a closed surface and includes a rivet terminal that is electrically connected to the first electrode and has the second polarity.

35. A battery pack including a plurality of the batteries according to any one of claims 30 to 34.

36. An automobile including the battery pack according to claim 35.

Images