Battery

Abstract

We aim to improve battery quality. [Solution] The battery 1 comprises a wound electrode group 2 in which a separator 10 and electrode plates are stacked and wound, and a current collector plate. The electrode group 2 has multiple electrode plates arranged in the radial direction B, the ends of which are bent in the radial direction B, and the bent ends are joined to the current collector plate. The bent ends have a first region 74 that bends to one side in the radial direction B, and a second region 76 that bends from the tip of the first region 74 to the other side in the radial direction B.

Description

[Technical Field]

[0001] The present disclosure relates to a battery including an electrode group and a current collector plate, and a method for joining the electrode group and the current collector plate. [Background Art]

[0002] Conventionally, batteries in which a wound electrode group and an electrolyte are housed in a cylindrical outer can are known. Regarding such a battery, Patent Document 1 discloses a method in which an end portion of an electrode group is bent to form a flat welding surface, and the welding surface and a current collector plate are welded together. [Prior Art Literature] [Patent Literature]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-106613 [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] When the end portion of the electrode group is bent, an excessive load may be applied to the root of the end portion when the current collector plate is pressed against the end portion. When a force is applied to the root of the end portion, peeling of the electrode active material layer or the like may occur, which can lead to deterioration in battery quality.

[0005] The present disclosure has been made in view of such circumstances, and one object thereof is to provide a technique for improving the quality of batteries. [Means for Solving the Problem]

[0006] One aspect of the present disclosure is a battery. The battery includes a wound electrode group in which separators and electrode plates are stacked and wound, and a current collector plate. In the electrode group, ends of a plurality of electrode plates arranged in a radial direction are bent in the radial direction, and the plurality of bent ends are joined to the current collector plate. The bent end portion has a first region that bends toward one side in the radial direction, and a second region that bends from the tip of the first region toward the other side in the radial direction.

[0007] Another aspect of the present disclosure is a method for joining a wound electrode group, in which separators and electrode plates are stacked and wound together, to a current collector plate. This joining method includes pressing a radially rotatable roller of the electrode group against the ends of a plurality of electrode plates arranged radially, displacing the roller to one side in the radial direction to bend the plurality of ends to one side, and rotating the roller so that the contact portion with the ends on the roller is displaced to the other side in the radial direction to bend the tips of the plurality of ends to the other side, thereby joining the bent plurality of ends to the current collector plate.

[0008] Any combination of the above components, as well as any conversion of the expressions of this disclosure between methods, apparatus, systems, etc., are also valid forms of this disclosure. [Effects of the Invention]

[0009] According to this disclosure, it is possible to improve the quality of batteries. [Brief explanation of the drawing]

[0010] [Figure 1] This is a cross-sectional view of a battery. [Figure 2] Figure 2(A) shows the electrode group formation process. Figure 2(B) shows the electrode group processing process. [Figure 3] Figures 3(A) to 3(C) show how the edges of the electrode plates deform during the manufacturing process of the electrode group. [Figure 4] This figure shows the electrode group and current collector plate after they have been joined together. [Modes for carrying out the invention]

[0011] The present disclosure will be described below with reference to the drawings, based on preferred embodiments. The embodiments are illustrative and not limiting, and not all features or combinations thereof described in the embodiments are necessarily essential to the present disclosure. The same or equivalent components, members, and processes shown in each drawing are denoted by the same reference numerals, and redundant descriptions are omitted where appropriate. The scale and shape of each part shown in each drawing are set for convenience to facilitate explanation and are not to be interpreted restrictively unless otherwise specified. Furthermore, where terms such as "first," "second," etc. are used in this specification or claims, unless otherwise specified, these terms do not indicate any order or importance, but are used to distinguish one configuration from another. In addition, some components that are not important for explaining the embodiments are omitted in each drawing.

[0012] Figure 1 is a cross-sectional view of battery 1. Battery 1 is a rechargeable secondary battery such as a lithium-ion battery, nickel-metal hydride battery, or nickel-cadmium battery. Battery 1 as an example has a structure in which an electrode group 2 is housed in an outer casing 4 together with an electrolyte (not shown). The electrode group 2 is, for example, cylindrical and has a wound structure in which a strip-shaped first electrode plate 6 and a strip-shaped second electrode plate 8 are stacked with a strip-shaped separator 10 in between and wound in a spiral shape (see also Figure 2(A)). In this embodiment, the first electrode plate 6 is the positive electrode plate and the second electrode plate 8 is the negative electrode plate. The separator 10 is, for example, made of a microporous film made of polypropylene resin or the like.

[0013] The first electrode plate 6 and the second electrode plate 8 have a structure in which an electrode active material layer is laminated onto a current collector. In the case of a typical lithium-ion secondary battery, the current collector is made of aluminum foil or the like if it is the positive electrode, and copper foil or the like if it is the negative electrode. The electrode active material layer can be formed by applying an electrode composite material to the surface of the current collector using a known coating device, drying, and rolling. The electrode composite material is obtained by kneading materials such as electrode active material, binder, and conductive material into a dispersion medium and dispersing them uniformly. In the case of a typical lithium-ion secondary battery, the electrode active material is lithium cobalt oxide or lithium iron phosphate for the positive electrode, and graphite for the negative electrode.

[0014] The first electrode plate 6 has a first uncoated portion 12 at one end in the width direction A (the direction intersecting the longitudinal direction of the strip) where the electrode composite material is not applied. The first uncoated portion 12 is an exposed portion of the current collector of the first electrode plate 6 where the electrode active material layer is not laminated. The second electrode plate 8 also has a second uncoated portion 14 at the other end in the width direction A, that is, the end opposite to the side from which the first uncoated portion 12 protrudes, where the electrode composite material is not applied. The second uncoated portion 14 is an exposed portion of the current collector of the second electrode plate 8 where the electrode active material layer is not laminated.

[0015] As described above, electrode group 2 has a structure in which the first electrode plate 6 and the second electrode plate 8 are wound together. Therefore, the ends of the first electrode plate 6 and the second electrode plate 8 in the width direction A are arranged in multiple locations in the radial direction B of electrode group 2. Thus, electrode group 2 has multiple first uncoated portions 12 and multiple second uncoated portions 14 arranged in the radial direction B.

[0016] Electrode group 2 has first bonding regions 46 formed by the ends of multiple first electrode plates 6 arranged in the radial direction B, i.e., the first uncoated portions 12, which are bent in the radial direction B. As an example, electrode group 2 has multiple first bonding regions 46 spaced at predetermined intervals in the circumferential direction of electrode group 2. For example, electrode group 2 has four first bonding regions 46 spaced at 90° intervals in the circumferential direction. Similarly, electrode group 2 has second bonding regions 48 formed by the ends of multiple second electrode plates 8 arranged in the radial direction B, i.e., the second uncoated portions 14, which are bent in the radial direction B. As an example, electrode group 2 has multiple second bonding regions 48 spaced at predetermined intervals in the circumferential direction of electrode group 2. For example, electrode group 2 has four second bonding regions 48 spaced at 90° intervals in the circumferential direction.

[0017] By providing a first bonding region 46 and a second bonding region 48 in a portion of the circumferential region of the electrode group 2, the circumferential deflection caused by bending of each uncoated portion can be absorbed in the non-bending region. This improves the welding quality between the electrode group 2 and the current collector plate, thereby improving the quality of the battery 1. Note that the electrode group 2 may have only one of the first bonding region 46 and the second bonding region 48.

[0018] Each end of the first electrode plate 6 bent in the first bonding region 46 has a first region 74 and a second region 76. The first region 74 is bent to one side in the radial direction B, and the second region 76 is bent from the tip of the first region 74 to the other side in the radial direction B. Similarly, each end of the second electrode plate 8 bent in the second bonding region 48 also has a first region 74 and a second region 76. The first region 74 is bent to one side in the radial direction B, and the second region 76 is bent from the tip of the first region 74 to the other side in the radial direction B. Note that only one of the first uncoated portion 12 and the second uncoated portion 14 may have both the first region 74 and the second region 76.

[0019] In the present embodiment, one side in the radial direction B is the inner side in the radial direction B, and the other side in the radial direction B is the outer side in the radial direction B. That is, the first region 74 is bent toward the winding center C of the electrode group 2 on the center side in the width direction A relative to the second region 76. The winding center C is, for example, the geometric center of the outer shape of the electrode group 2 when viewed from the width direction A, in other words, the geometric center of the outer shape of the projection shape of the electrode group 2 in the width direction A. The second region 76 is bent and extends from the outer end of the first region 74 in the width direction A toward the outer side in the radial direction B. It should be noted that one side in the radial direction B may be the outer side in the radial direction B, and the other side in the radial direction B may be the inner side in the radial direction B.

[0020] A first current collector plate 20 is disposed on the side of the electrode group 2 from which the first uncoated portions 12 protrude. The first current collector plate 20 is made of, for example, aluminum or the like. End portions of the plurality of first electrode plates 6 bent in the first joining region 46 are in surface contact with the first current collector plate 20. Bending the end portion of each first electrode plate 6 increases the contact area between each first uncoated portion 12 and the first current collector plate 20. Then, laser welding or the like is performed at a position where the first joining region 46 and the first current collector plate 20 overlap each other. Thereby, the first electrode plates 6 of each winding layer and the first current collector plate 20 are joined to each other. At the end portion of the first electrode plate 6, mainly the second region 76 is joined to the first current collector plate 20.

[0021] A second current collector plate 22 is disposed on the side of the electrode group 2 from which the second uncoated portions 14 protrude. The second current collector plate 22 is made of, for example, copper, nickel, nickel-plated copper, nickel-plated iron, or the like. End portions of the plurality of second electrode plates 8 bent in the second joining region 48 are in surface contact with the second current collector plate 22. Bending the end portion of each second electrode plate 8 increases the contact area between each second uncoated portion 14 and the second current collector plate 22. Then, laser welding or the like is performed at a position where the second joining region 48 and the second current collector plate 22 overlap each other. Thereby, the second electrode plates 8 of each winding layer and the second current collector plate 22 are joined to each other. At the end portion of the second electrode plate 8, mainly the second region 76 is joined to the second current collector plate 22.

[0022] The electrode group 2, to which the first current collector plate 20 and the second current collector plate 22 are joined, is housed together with an electrolytic solution in a bottomed cylindrical outer can 4. The outer can 4 is made of, for example, copper, nickel, iron, or an alloy thereof. The second current collector plate 22 is joined to the inner bottom surface of the outer can 4 by welding or the like. The first current collector plate 20 is joined to a sealing plate 26 made of the same metal as the outer can 4 by welding or the like. The sealing plate 26 is fitted into the opening of the outer can 4 via an insulating gasket 24. Thereby, the electrode group 2 and the electrolytic solution are sealed inside the outer can 4.

[0023] Next, a method for joining the electrode group 2 and the current collector plates will be described. Hereinafter, the method for joining the electrode group 2 and the current collector plates will be described taking the joining of the first joining region 46 and the first current collector plate 20 as an example. The joining of the second joining region 48 and the second current collector plate 22 is the same as that of the first joining region 46. Note that only one of the first joining region 46 and the second joining region 48 may be formed by the method according to the present embodiment and joined to the current collector plate.

[0024] Fig. 2(A) is a diagram showing the forming step of the electrode group 2. In Fig. 2(A), illustration of the first uncoated portion 12 and the second uncoated portion 14 is omitted. Fig. 2(B) is a diagram showing the processing step of the electrode group 2. Figs. 3(A) to 3(C) are diagrams showing how end portions of electrode plates are deformed in the processing step of the electrode group 2. Fig. 4 is a diagram showing a state after the electrode group 2 and the current collector plates are joined.

[0025] First, as shown in Fig. 2(A), a belt-shaped first electrode plate 6, a belt-shaped second electrode plate 8, and a separator 10 are prepared respectively. Then, the separator 10, the first electrode plate 6, the separator 10, and the second electrode plate 8 are stacked in this order. The obtained laminate is spirally wound to form the wound-type electrode group 2.

[0026] Next, as shown in Figure 2(B), the electrode group 2 is set in the processing device 28. The processing device 28 comprises a stage 30, a pair of processing tools 78, a roller rotation mechanism 80, and a frame 36. As an example, the stage 30 has a circular groove 30b into which the ends of the electrode group 2 fit, and the electrode group 2 is fixed by fitting the ends into this groove 30b. The method of fixing the electrode group 2 is not particularly limited. The electrode group 2 is positioned so that the winding center C extends in the direction normal to the stage 30. In Figure 2(B), the electrode group 2 is positioned so that the first uncoated portion 12 faces away from the stage 30. The stage 30 can rotate the electrode group 2 around the winding center C.

[0027] A pair of workpieces 78 are positioned opposite the stage 30, with the electrode group 2 in between. Each workpiece 78 is supported by the frame 36 so as to be slidable in the radial direction B. The frame 36 also supports a drive unit (not shown) that slides each workpiece 78 in the radial direction B. The drive unit can be composed of, for example, a motor or a cam mechanism. Each workpiece 78 has a roller 82 facing the electrode group 2. Each roller 82 is supported by each workpiece 78 so as to be rotatable in the radial direction B. Each roller 82 is pressed against the end of a plurality of electrode plates (the first uncoated portion 12 in Figure 2(B)).

[0028] The roller rotation mechanism 80 is supported by the frame 36. As an example, the roller rotation mechanism 80 is configured similarly to a rack and pinion mechanism, and includes a rack rail 84, a first pinion 86, and a second pinion 88. The rack rail 84 is supported by the frame 36 and extends radially B. The first pinion 86 engages with the rack rail 84 and is supported by the workpiece 78. The second pinion 88 engages with the first pinion 86 and is supported by the workpiece 78. The second pinion 88 and the roller 82 are connected by a rotating shaft 90 that extends perpendicular to the radial direction B. When the second pinion 88 rotates, torque is transmitted to the roller 82 via the rotating shaft 90, causing the roller 82 to rotate. In this embodiment, the first pinion 86 and the second pinion 88 are provided for the roller 82 of each workpiece 78, and the rack rail 84 is common to all rollers 82.

[0029] Each processing tool 78 slides toward one side of the radial direction B with the roller 82 pressed against a plurality of first uncoated portions 12 arranged in the radial direction B. As a result, the entire roller 82 is displaced to one side of the radial direction B. In addition, each roller 82 rotates so that the contact portion of the roller 82 with the end of the electrode plate (the first uncoated portion 12 in Figure 2(B)), that is, the portion of the roller 82 facing the stage 30, is displaced to the other side of the radial direction B.

[0030] As an example, with each workpiece 78 positioned at the outermost end of the radial direction B, the roller 82 is pressed against the first uncoated area 12. Then, each workpiece 78 slides inward in the radial direction B. As a result, the entire roller 82 is displaced inward in the radial direction B. Due to this displacement of the roller 82, as shown in Figure 3(A), the end of the first uncoated area 12 is bent inward, forming the first region 74.

[0031] The first pinion 86 and the second pinion 88, supported by each workpiece 78, are also displaced inward in the radial direction B along with the roller 82. At this time, the first pinion 86 moves along the rack rail 84 and rotates due to its meshing with the rack rail 84. The first pinion 86 rotates such that the part facing the stage 30 is displaced inward in the radial direction B. The second pinion 88 rotates due to its meshing with the first pinion 86. The second pinion 88 rotates in the opposite direction to the first pinion 86, that is, the part facing the stage 30 is displaced outward in the radial direction B. The rotational torque of the second pinion 88 is transmitted to the roller 82 via the rotating shaft 90, causing the roller 82 to rotate as well.

[0032] Each roller 82 rotates such that the contact portion of the roller 82 with the first uncoated portion 12, that is, the portion of the roller 82 facing the stage 30, is displaced outward in the radial direction B. Friction occurs between the circumferential surface of the roller 82 and the first uncoated portion 12. As a result of the rotation of the roller 82, as shown in Figure 3(B), the tip of the first uncoated portion 12 is bent outward in the radial direction B, and a second region 76 is formed at the tip of the first region 74.

[0033] Each roller 82 is rotated at a faster speed than when it is driven by contact with the ends of the multiple electrode plates when the entire roller 82 is displaced to one side in the radial direction B by the sliding of the workpiece 78. This makes it easier to raise the leading edge of the first region 74. Preferably, the roller 82 is made of resin. This increases the frictional force against the first uncoated portion 12 and the second uncoated portion 14, which are made of metal. Thus, it is easier to form the second region 76. Urethane is an example of a resin that makes up the roller 82.

[0034] Such active rotation of the rollers 82 can be achieved by adjusting the reduction ratio (gear ratio) of the rack rail 84, the first pinion 86, and the second pinion 88. If the roller rotation mechanism 80 is not provided, each roller 82 rotates in a driven manner along with the slide of the workpiece 78 due to friction with the first uncoated portion 12. When the rotational speed of the rollers 82 at this time (the amount of rotation of the rollers 82 per unit displacement of the workpiece 78) is taken as 1, the roller rotation mechanism 80 rotates the rollers 82 so that the rotational speed is greater than 1, for example, 1.25 or more.

[0035] Next, as shown in Figure 3(C), each processing tool 78 slides further inward in the radial direction B, forming a first region 74 on the adjacent first uncoated portion 12. This operation is repeated thereafter, forming a first region 74 and a second region 76 at the tip of the first uncoated portion 12 over the entire radial direction B. In other words, each first uncoated portion 12 is pressed in a straight line passing through the winding center C when viewed from the extending direction of the winding center C, forming the first region 74 and the second region 76. This is the first stage of the processing process, and in the subsequent second stage, the electrode group 2 is rotated 90° around the winding center C, and the pair of processing tools 78 again press each first uncoated portion 12 in a straight line passing through the winding center C. As a result, a first bonding region 46 is formed in a cross shape on the electrode group 2.

[0036] After the first joining region 46 is formed, the first current collector plate 20 is pressed against the electrode group 2. Then, as shown in Figure 4, laser welding or the like is performed at the position where the first joining region 46 and the first current collector plate 20 overlap to form a joint 44. As a result, the multiple bent first uncoated portions 12 in the first joining region 46 are joined to the first current collector plate 20. The electrode group 2 to which the first current collector plate 20 has been joined is positioned so that the second uncoated portions 14 face away from the stage 30 and fixed to the stage 30. Then, the above-described processing is performed on the second uncoated portions 14 using a pair of processing tools 78. As a result, a cross-shaped second joining region 48 is formed on the electrode group 2. Then, the multiple bent second uncoated portions 14 in the second joining region 48 are joined to the second current collector plate 22 by laser welding or the like.

[0037] The electrode group 2, to which the first current collector plate 20 and the second current collector plate 22 are joined, is housed in the outer casing 4 along with the electrolyte. Further processing, such as joining the second current collector plate 22 to the outer casing 4, joining the first current collector plate 20 to the sealing plate 26, and fitting the sealing plate 26 into the opening of the outer casing 4, is performed to obtain the battery 1. The order of processing, such as joining the parts, housing in the outer casing 4, and fitting the sealing plate 26, can be changed as appropriate. For example, if the sealing plate 26 has an injection port, the electrolyte may be injected into the outer casing 4 after the sealing plate 26 has been fitted into the opening of the outer casing 4.

[0038] As described above, the electrode group 2 of the battery 1 according to this embodiment has multiple electrode plates arranged in the radial direction B, the ends of which are bent in the radial direction B, and the bent ends are joined to the current collector plate. The bent ends have a first region 74 that bends to one side in the radial direction B, and a second region 76 that bends from the tip of the first region 74 to the other side in the radial direction B.

[0039] When a current collector plate is joined to the end of an electrode plate, a load is applied to the end of the electrode plate when the current collector plate is pressed against the electrode group 2. If the end of the electrode plate only has a first region 74, this load is concentrated in the portion of the electrode plate where the electrode active material layer is laminated, which may cause buckling in that portion and lead to delamination of the electrode active material layer. In contrast, in this embodiment, a second region 76 is provided at the tip of the first region 74, which is folded back to the opposite side, and the current collector plate is pressed against this second region 76. This allows the load applied to the electrode plate when the current collector plate is pressed to be concentrated in the region including the connection between the first region 74 and the second region 76. As a result, delamination of the electrode active material layer can be suppressed, and the quality of the battery 1 can be improved.

[0040] Furthermore, in this embodiment, the first region 74 is tilted inward in the radial direction B, and the second region 76 is tilted outward in the radial direction B. This makes it easier and more stable to form the first region 74 and the second region 76 compared to the case where the first region 74 is tilted outward and the second region 76 is tilted inward. Thus, the bonding stability between the electrode plate and the current collector plate of each winding layer can be improved, and the quality of the battery 1 can be improved.

[0041] Furthermore, the method for joining the electrode group 2 and the current collector plate according to this embodiment includes pressing a roller 82 rotatable in the radial direction B against the ends of a plurality of electrode plates, displacing the roller 82 to one side in the radial direction B to bend the plurality of ends to one side, and rotating the roller 82 so that the contact portion of the roller 82 with the end of the electrode plate is displaced to the other side in the radial direction B to bend the tips of the plurality of ends to the other side, thereby joining the bent plurality of ends to the current collector plate.

[0042] By pressing the roller 82 against the edge of the electrode plate and sliding it radially in direction B, a first region 74 can be formed at the edge of the electrode plate. Furthermore, by rotating the roller 82 along with this sliding motion, a second region 76 can be formed at the tip of the first region 74. Therefore, according to this embodiment, the first region 74 and the second region 76 can be easily formed at the edge of the electrode plate.

[0043] Furthermore, in this embodiment, the roller 82 is rotated at a faster speed than when it is driven by contact with the edge of the electrode plate when the roller 82 is displaced to one side in the radial direction B. This makes it easier to fold back the tip of the first region 74. Therefore, the second region 76 can be formed more easily, thereby improving the quality of the battery 1. Also, the roller 82 is made of resin. This allows for increased friction against the uncoated portion made of metal foil compared to when the roller 82 is made of metal, making it easier to form the second region 76. Therefore, the quality of the battery 1 can be improved.

[0044] The embodiments of this disclosure have been described in detail above. The embodiments described above are merely examples of how to implement this disclosure. The content of the embodiments does not limit the technical scope of this disclosure, and many design changes, such as changes, additions, and deletions of components, are possible as long as they do not depart from the spirit of the invention as defined in the claims. A new embodiment with design changes will have the combined effects of both the embodiment and the variation. In the embodiments described above, the content in which such design changes are possible is emphasized with notations such as "of this embodiment" or "in this embodiment," but design changes are also permitted even if there are no such notations. Furthermore, any combination of components included in each embodiment is also valid as an embodiment of this disclosure. The hatching applied to the cross-section in the drawings does not limit the material of the object to which the hatching is applied.

[0045] The embodiments may be specified by the items described below. [1st item] A wound electrode group (2) is formed by stacking and winding a separator (10) and electrode plates (6,8), Equipped with current collector plates (20, 22), The electrode group (2) consists of multiple electrode plates (6,8) arranged radially (B), with their ends bent radially (B), and these bent ends are joined to the current collector plates (20,22). The bent end has a first region (74) that bends to one side in the radial direction (B), and a second region (76) that bends to the other side in the radial direction (B) from the tip of the first region (74). Batteries (1). [Second item] One side is on the inside in the radial direction (B), The other side is the outer side in the radial direction (B), The battery (1) described in item 1. [3rd item] A method for joining a wound-type electrode group (2) in which separators (10) and electrode plates (6,8) are stacked and wound together, to current collector plates (20,22), A roller (82) of the electrode group (2) that is rotatable in the radial direction (B) is pressed against the ends of multiple electrode plates (6,8) arranged in the radial direction (B), and the roller (82) is displaced to one side in the radial direction (B) to bend the multiple ends to one side, and the roller (82) is rotated so that the contact portion of the roller (82) with the ends is displaced to the other side in the radial direction (B) to bend the tips of the multiple ends to the other side. This includes joining multiple bent ends to the current collector plates (20, 22), Joining method. [4th item] The roller (82) is rotated at a faster speed when displaced to one side than when it is driven by contact with multiple ends. The joining method described in item 3. [Item 5] The ends of the electrode plates (6,8) are made of metal. The roller (82) is made of resin. The joining method described in item 3 or item 4. [Industrial applicability]

[0046] This disclosure can be used for a battery comprising an electrode group and a current collector plate, and for a method of joining the electrode group and the current collector plate. [Explanation of Symbols]

[0047] 1 Battery, 2 Electrode groups, 6 First electrode plate, 8 Second electrode plate, 10 Separator, 20 First current collector plate, 22 Second current collector plate, 46 First junction region, 48 Second junction region, 74 First region, 76 Second region, 82 Roller.

Claims

1. A group of electrodes is formed by stacking separators and electrode plates and winding them around a winding center, The electrode plate is connected to a current collector plate, The electrode plate has electrode plate ends in the width direction of the electrode group where no electrode active material layer is formed. The electrode plate end portion has a first region and a second region adjacent to the first region. battery.

2. The first region is folded toward the winding center, The battery according to claim 1.

3. The second region extends from the outer end of the first region in the width direction toward the winding center, The battery according to claim 2.

4. The current collector plate is joined to the second region. The battery according to any one of claims 1 to 3.

5. Between the first region and the second region, there is a bent portion in which the direction in which the electrode plate end extends is switched. The battery according to claim 3.

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