Battery manufacturing method

Abstract

This battery manufacturing method includes: preparation of a wound-type electrode group 2 formed by laminating and winding separators and electrode plates such that the electrode group 2 has recessed parts 70 in first regions R1, which continue from an inner edge at one end in an axial direction E, electrode plates being shorter at the recessed parts 70 than in second regions R2 positioned on the outer side of the first regions R1; bending of end parts of the electrode plates in the second regions R2 in a radial direction B of the electrode group 2; joining of the bent end parts with a collector plate; insertion of the electrode group 2 joined with the collector plate into an exterior can 4 so that the collector plate and a bottom surface of the exterior can 4 face each other; insertion of a press jig 72 into a center space of the electrode group 2; and pressing of the collector plate against the bottom surface to join the collector plate with the exterior can 4.

Description

[Technical Field]

[0001] The present disclosure relates to a battery manufacturing method and a battery. [Background Art]

[0002] Conventionally, there has been known a battery in which a wound electrode group and an electrolytic solution are housed in a cylindrical outer can. Regarding such a battery, Patent Document 1 discloses a method of bending an end portion of the electrode group to form a flat welding surface, and welding the welding surface and a current collector plate. [Prior Art Document] [Patent Document]

[0003] [Patent Document 1] Japanese Patent Laying-Open No. 2000-323117 [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] The present inventors have found that when the end portion of the electrode group is bent as in Patent Document 1, depending on the battery manufacturing method, the bent end portion of the electrode plate may hinder the performance of the battery manufacturing process. If the performance of the battery manufacturing process is hindered, this may lead to a decrease in the quality of the obtained battery.

[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 a battery. [Means for Solving the Problem]

[0006] One aspect of the present disclosure is a method for manufacturing a battery. This manufacturing method includes preparing a wound electrode group in which separators and electrode plates are stacked and wound, having an electrode group having a recess in a first region continuous from the inner edge of one end in the axial direction, in which the electrode plate is shorter than that of a second region located on the outer edge side of the first region, bending the end of the electrode plate in the second region in the radial direction of the electrode group, joining the bent end to a current collector plate, inserting the electrode group with the current collector plate joined to it into an outer casing, facing the current collector plate to the bottom surface of the outer casing, inserting a pressing device into the central space of the electrode group, and pressing the current collector plate to the bottom surface to join the current collector plate to the outer casing.

[0007] Another aspect of the present disclosure is a battery. This battery comprises a wound electrode group in which separators and electrode plates are stacked and wound, and a current collector plate. The electrode group has a recess in a first region continuous with the inner edge of one end in the axial direction, in which the electrode plates are shorter than those in a second region located on the outer edge side of the first region, and the ends of the electrode plates in the second region are bent radially in the electrode group, and the bent ends are joined 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 process of forming the electrode group. Figure 2(B) shows the process of joining the electrode group to the second current collector plate. [Figure 3] This is a plan view showing the first electrode plate before winding. [Figure 4] Figure 4(A) shows the joining process between the second current collector plate and the outer casing. Figure 4(B) shows the joining process between the electrode group and the first current collector plate. [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 type 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, but the polarity of the first electrode plate 6 and the second electrode plate 8 may be reversed. The separator 10 is, for example, made of a microporous film made of polypropylene resin or the like.

[0013] The first electrode plate 6 has a structure in which an electrode active material layer 6b is laminated on a current collector 6a. Similarly, the second electrode plate 8 has a structure in which an electrode active material layer 8b is laminated on a current collector 8a. In the case of a typical lithium-ion secondary battery, the current collectors 6a and 8a are made of aluminum foil or the like if they are the positive electrode, and copper foil or the like if they are the negative electrode. The electrode active material layers 6b and 8b can be formed by applying an electrode composite material to the surface of the current collectors 6a and 8a 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 in 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 if it is the positive electrode, and graphite if it is the negative electrode.

[0014] The first electrode plate 6 has a first uncoated portion 12 at one end in the width direction A, where the electrode composite material is not applied. The width direction A is the direction that intersects the longitudinal direction of the strip and is the direction in which the winding center C of the electrode group 2 extends, in other words, the same direction as the axial direction E of the electrode group 2. The first uncoated portion 12 is an exposed portion of the current collector 6a where the electrode active material layer 6b is not laminated. The second electrode plate 8 has a second uncoated portion 14 at the other end in the width direction A (axial direction E), 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 8a where the electrode active material layer 8b 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] The electrode group 2 has a recess 70 in a first region R1 that is continuous with the inner edge 68 at one end in the axial direction E (the end facing the bottom surface of the outer can 4), where the second electrode plate 8 is shorter than in the second region R2 located on the outer edge side of the first region R1. Specifically, the length of the current collector 8a (second uncoated portion 14) of the second electrode plate 8 located in the first region R1 is shorter than that of the second electrode plate 8 located in the second region R2. The end of the second electrode plate 8 in the second region R2 is bent in the radial direction B of the electrode group 2. In this embodiment, the end of each second electrode plate 8 is bent toward the winding center C. As an example, the second electrode plates 8 in the second region R2 are bent radially B at predetermined intervals in the circumferential direction of the electrode group 2.

[0017] Furthermore, the electrode group 2 has a recess 70 in a first region R1 that is continuous with the inner edge 68 at the other end in the axial direction E (the end facing the opening side of the outer can 4), where the first electrode plate 6 is shorter than in the second region R2 located on the outer edge side of the first region R1. Specifically, the length of the current collector 6a (first uncoated portion 12) of the first electrode plate 6 located in the first region R1 is shorter than that of the first electrode plate 6 located in the second region R2. The end of the first electrode plate 6 in the second region R2 is bent in the radial direction B of the electrode group 2. In this embodiment, the end of each first electrode plate 6 is bent toward the winding center C. As an example, the first electrode plate 6 in the second region R2 is bent radially B at predetermined intervals in the circumferential direction of the electrode group 2. Note that the electrode group 2 only needs to have a recess 70 at the end facing the bottom side of the outer can 4.

[0018] A first current collector plate 20 is positioned on the side of the electrode group 2 where the first uncoated portion 12 protrudes. The first current collector plate 20 is made of, for example, aluminum. The ends of the multiple first electrode plates 6 that are bent in the second region R2 are in surface contact with the first current collector plate 20. The bending of the ends of each first electrode plate 6 increases the contact area between each first electrode plate 6 and the first current collector plate 20. Then, each first electrode plate 6 and the first current collector plate 20 are joined to each other by laser welding or the like. As a result, the first electrode plates 6 and the first current collector plate 20 are electrically connected.

[0019] A second current collector plate 22 is arranged on the side of the electrode group 2 where 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 region R2 are in surface contact with the second current collector plate 22. Bending of the end portion of each second electrode plate 8 increases the contact area between each second electrode plate 8 and the second current collector plate 22. Then, each second electrode plate 8 and the second current collector plate 22 are joined to each other by laser welding or the like. Thereby, the second electrode plates 8 and the second current collector plate 22 are electrically connected to each other.

[0020] The electrode group 2 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, an alloy thereof, or the like. The second current collector plate 22 joined to the electrode group 2 is joined to the inner bottom surface of the outer can 4 by welding or the like. The first current collector plate 20 joined to the electrode group 2 is joined by welding or the like to a sealing plate 26 made of the same metal as that of the outer can 4. 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.

[0021] Next, a method for manufacturing the battery 1 will be described in more detail. Fig. 2(A) is a diagram showing a step of forming the electrode group 2. Fig. 2(B) is a diagram showing a step of joining the electrode group 2 and the second current collector plate 22. Fig. 4(A) is a diagram showing a step of joining the second current collector plate 22 and the outer can 4. Fig. 4(B) is a diagram showing a step of joining the electrode group 2 and the first current collector plate 20.

[0022] First, as shown in Figure 2(A), strip-shaped first electrode plate 6, second electrode plate 8, and separator 10 are prepared. Then, the separator 10, first electrode plate 6, separator 10, and second electrode plate 8 are stacked in this order. The resulting stack is wound in a spiral shape to form a wound electrode group 2. At this time, the first electrode plate 6 and second electrode plate 8, whose ends corresponding to the recess 70 have been pre-cut, and the separator 10 are wound together to form the electrode group 2. In other words, each electrode plate has its end in the width direction A cut out in a predetermined range corresponding to the first region R1 from the end on the winding start side in the longitudinal direction of the strip.

[0023] This makes it possible to obtain an electrode group 2 having a recess 70 in the first region R1 at the end in the axial direction E simply by winding each electrode plate and separator 10. Alternatively, the recess 70 may be formed by cutting off the ends of each electrode plate in the first region R1 after winding each electrode plate and separator 10. However, cutting before winding makes the processing easier and avoids the risk of chips and other debris getting mixed into the electrode group 2.

[0024] Here, the configuration of the first electrode plate 6 and the second electrode plate 8 before winding will be explained using Figure 3. Figure 3 is a plan view showing the first electrode plate 6 before winding. The vertical direction in Figure 3 corresponds to the width direction A described so far. In the first electrode plate 6 before winding, the current collector 6a is exposed from one end in the width direction of the strip-shaped electrode active material layer 6b. The first electrode plate 6 also includes a first region portion 6r1 that is included in the first region R1 when the first electrode plate 6 is wound, and a second region portion 6r2 that is included in the second region R2 when the first electrode plate 6 is wound. The length in the width direction of the first electrode plate 6 in the first region portion 6r1 is shorter than the length in the width direction of the first electrode plate 6 in the second region portion 6r2.

[0025] Furthermore, the length of the strip of the first electrode plate 6 in the longitudinal direction is shown as L, and the length of the first region portion 6r1 in the longitudinal direction of the strip of the first electrode plate 6 is L R1 It is shown that the length of the second region portion 6r2 in the longitudinal direction of the strip of the first electrode plate 6 is L R2 This is shown. L R1This is preferably 15% or less of L, and more preferably 10% or less of L. This suppresses the risk of insufficient electrical connection between the electrode plate and the current collector plate. The second electrode plate 8 has the same configuration as the first electrode plate 6. Return to Figure 2(A).

[0026] The recess 70 is formed by cutting off the exposed portion of the current collectors 6a and 8a on each electrode plate. At this time, as shown in Figures 1 and 3, it is preferable to cut off the exposed portion so that a part of the exposed portion remains. If the exposed portion is cut off right up to the point where the electrode active material layers 6b and 8b and the current collectors 6a and 8a overlap, the electrode active material layers 6b and 8b may become prone to peeling. In contrast, by leaving the exposed portion, peeling of the electrode active material layers 6b and 8b can be suppressed.

[0027] Next, as shown in Figure 2(B), the end of the second electrode plate 8 in the second region R2 is bent radially in the direction B. The end of the first electrode plate 6 in the second region R2 is also bent radially in the direction B. The method for bending the first electrode plate 6 and the second electrode plate 8 is not particularly limited. For example, the first electrode plate 6 and the second electrode plate 8 in the second region R2 can be bent by pressing a jig (not shown) having a plane perpendicular to the axial direction E against the end of the electrode group 2 in the axial direction E.

[0028] The jig may overlap the first region R1. Since the first electrode plate 6 and the second electrode plate 8 in the first region R1 are shorter than the first electrode plate 6 and the second electrode plate 8 in the second region R2, even if the jig overlaps the first region R1, the first electrode plate 6 and the second electrode plate 8 in the first region R1 will not be bent, or if they are bent, the amount of bending will be less than that in the second region R2. Preferably, the depth of the recess 70 is set so that the first electrode plate 6 and the second electrode plate 8 in the first region R1 do not come into contact with the jig. Furthermore, it is preferable that the radial dimension B from the inner edge 68 of the recess 70 is greater than or equal to the depth of the recess 70. This makes it possible to more reliably suppress the tip of the first electrode plate 6 and the second electrode plate 8 in the second region R2 from extending beyond the inner edge 68 towards the winding center C when they are bent.

[0029] Then, the end of the second electrode plate 8, which has been bent in the second region R2, and the second current collector plate 22 are joined by laser welding or the like. Next, as shown in Figure 4(A), the electrode group 2 to which the second current collector plate 22 has been joined is inserted into the outer casing 4. The electrode group 2 is inserted into the outer casing 4 from the side of the second current collector plate 22. As a result, the second current collector plate 22 and the bottom surface of the outer casing 4 face each other. Then, a rod-shaped pressing tool 72 is inserted into the central space of the electrode group 2 from the opening side of the outer casing 4, and the second current collector plate 22 is pressed against the bottom surface of the outer casing 4 by the pressing tool 72. In this state, the second current collector plate 22 and the outer casing 4 are joined by laser welding or the like.

[0030] The pressing device 72 can create a state in which the second current collector plate 22 and the bottom surface of the outer casing 4 are in close contact, thereby improving the quality of the bond between the second current collector plate 22 and the outer casing 4. In addition, the electrode group 2 has a recess 70 at the end facing the second current collector plate 22, adjacent to the pressing device 72. This prevents the bent end of the second electrode plate 8 from being pinched between the pressing device 72 and the second current collector plate 22 when the pressing device 72 is inserted into the central space of the electrode group 2. As a result, a state in which the second current collector plate 22 and the bottom surface of the outer casing 4 are in close contact can be created more stably.

[0031] Furthermore, as described above, the electrode group 2 of this embodiment also has a recess 70 on the other end side in the axial direction E, that is, on the opening side of the outer container 4. This makes it possible to suppress contact between the end of the first electrode plate 6 and the pressing tool 72 when the pressing tool 72 is inserted into the central space of the electrode group 2, thereby suppressing unintended bending of the first electrode plate 6 and the generation of dust due to contact between the two.

[0032] Next, as shown in Figure 4(B), the pressing tool 72 is removed, and the end of the first electrode plate 6, which is bent in the second region R2, is joined to the first current collector plate 20 by laser welding or the like. After that, as shown in Figure 1, the first current collector plate 20 and the sealing plate 26 are joined together, and after the electrolyte is poured into the outer casing 4, the sealing plate 26 is fitted into the opening of the outer casing 4 via the insulating gasket 24. This completes the battery 1. In the case of a battery with a liquid filling port, the electrolyte may be poured into the outer casing 4 after the sealing body has been fitted into the opening of the outer casing 4.

[0033] As described above, the manufacturing method of the battery 1 according to this embodiment includes preparing an electrode group 2 having a recess 70 in a first region R1 that is continuous with the inner edge 68 at one end in the axial direction E (the end on which the second uncoated portion 14 protrudes), in which the second electrode plate 8 is shorter than that of the second region R2 located on the outer edge side; bending the end of the second electrode plate 8 in the second region R2 in the radial direction B and joining the bent end with the second current collector plate 22; inserting the electrode group 2 with the second current collector plate 22 joined into the outer casing 4; facing the second current collector plate 22 with the bottom surface of the outer casing 4; inserting a pressing device 72 into the central space of the electrode group 2 and pressing the second current collector plate 22 against the bottom surface to join the second current collector plate 22 with the outer casing 4.

[0034] In general, during the manufacturing process of batteries, a current collector plate is welded to one end of the electrode group, and then the electrode group is inserted into the outer casing from the current collector plate side, with the current collector plate and the bottom surface of the outer casing facing each other. A pressing tool is then inserted into the central space of the electrode group to press the current collector plate against the bottom surface of the outer casing, joining them in a tightly sealed state. In such a manufacturing process, if the end of the electrode plate is bent to increase the bonding area between the electrode group and the current collector plate, the bent end may protrude into the central space into which the pressing tool 72 is inserted. When the electrode plate protrudes into this space, it gets caught between the pressing tool 72 and the second current collector plate 22, making the pressing of the second current collector plate 22 by the pressing tool 72 unstable, and making it difficult to stably create a tightly sealed state between the second current collector plate 22 and the bottom surface of the outer casing 4.

[0035] In contrast, in this embodiment, a recess 70 is provided in the first region R1 that is continuous with the inner edge 68. This prevents the electrode plate from protruding into the central space into which the pressing device 72 is inserted, even when the electrode plate is bent. Therefore, it becomes possible to create a more stable state in which the second current collector plate 22 and the bottom surface of the outer casing 4 are in close contact. As a result, the quality of the joint between the second current collector plate 22 and the outer casing 4 can be improved, and the quality of the battery 1 can be improved.

[0036] Furthermore, the electrode group 2 of this embodiment also has a recess 70 on the other end side in the axial direction E (the end side on which the first uncoated portion 12 protrudes). This makes it easier to insert the pressing tool 72 into the central space of the electrode group 2. Also, the radial dimension B from the inner edge 68 of the recess 70 is greater than or equal to the depth of the recess 70 (dimension in the axial direction E). This makes it possible to more reliably prevent the bent electrode plate from protruding into the central space of the electrode group 2. Furthermore, the electrode group 2 is formed by winding the first electrode plate 6 and the second electrode plate 8, whose ends corresponding to the recess 70 have been pre-cut, with the separator 10. This makes it easier to provide the recess 70 to the electrode group 2. In addition, the recess 70 is formed by cutting off the exposed portions of the current collectors 6a and 8a, and this includes cutting in a way that leaves some exposed portions. This makes it possible to prevent the electrode active material layers 6b and 8b from peeling off from the current collectors 6a and 8a.

[0037] 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.

[0038] 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), and the electrode group (2) is provided having a recess (70) in a first region (R1) that is continuous from the inner edge (68) at one end in the axial direction (E), in which the electrode plate (8) is shorter than in a second region (R2) located on the outer edge side of the first region (R1), The end of the electrode plate (8) in the second region (R2) is bent in the radial direction (B) of the electrode group (2), and the bent end is joined to the current collector plate (22). Insert the electrode group (2) to which the current collector plate (22) is attached into the outer casing (4), and position the current collector plate (22) and the bottom surface of the outer casing (4) opposite each other. This includes inserting a pressing device (72) into the central space of the electrode group (2) and pressing the current collector plate (22) against the bottom surface to join the current collector plate (22) and the outer casing (4), A method for manufacturing a battery (1). [Second item] The electrode group (2) also has a recess (70) on the other end side in the axial direction (E). A method for manufacturing the battery (1) described in item 1. [3rd item] The radial dimension (B) of the recess (70) from the inner edge (68) is greater than or equal to the depth of the recess (70). A method for manufacturing the battery (1) described in item 1 or item 2. [4th item] The method includes winding together electrode plates (6,8) whose ends corresponding to the recesses (70) have been pre-cut and a separator (10) to form an electrode group (2). A method for manufacturing a battery (1) as described in any of items 1 to 3. [Item 5] The electrode plate (6,8) has a current collector (6a,8a) and an electrode active material layer (6b,8b) laminated on the current collector (6a,8a). The current collector (6a, 8a) has an exposed portion at one end in the axial direction (E) where the electrode active material layer (6b, 8b) is not laminated. The recess (70) is formed by cutting away the exposed portion. When removing exposed tissue, this includes removing tissue in a way that leaves some exposed tissue behind. A method for manufacturing a battery (1) as described in any of items 1 through 4. [Item 6] A wound electrode group (2) is formed by stacking and winding a separator (10) and electrode plates (6,8), It is equipped with current collector plates (20, 22), The electrode group (2) has a first region (R1) that is continuous from the inner edge (68) at one end in the axial direction (E), and a recess (70) in which the electrode plates (6,8) are shorter than those in the second region (R2) located on the outer edge side of the first region (R1). The ends of the electrode plates (6,8) in the second region (R2) are bent in the radial direction (B) of the electrode group (2), and the bent ends are joined to the current collector plates (20,22). Batteries (1). [Industrial applicability]

[0039] This disclosure can be used in a method for manufacturing a battery and in a battery. [Explanation of Symbols]

[0040] 1 Battery, 2 Electrode group, 4 Outer casing, 6a Current collector, 6b Electrode active material layer, 8a Current collector, 8b Electrode active material layer, 10 Separator, 68 Inner edge, 70 Recess, 72 Pressing device, R1 First region, R2 Second region.

Claims

1. A wound electrode group in which separators and electrode plates are stacked and wound, wherein an electrode group is provided having a recess in a first region continuous from the inner edge of one end in the axial direction, in which the electrode plate is shorter than in a second region located on the outer edge side of the first region, The end of the electrode plate in the second region is bent in the radial direction of the electrode group, and the bent end is joined to the current collector plate. Insert the electrode group to which the current collector plate is attached into the outer can, and position the current collector plate and the bottom surface of the outer can facing each other. This includes inserting a pressing device into the central space of the electrode group, pressing the current collector plate against the bottom surface, and joining the current collector plate and the outer casing by laser bonding, The end of the electrode plate in the recess is either not bent at all when the end of the electrode plate in the second region is bent, or bent less than the end of the electrode plate in the second region, and the recess is formed after bending by the bending. The recessed portion after bending is positioned adjacent to the pressing device in the process of inserting the pressing device into the central space of the electrode group, while the pressing device is pressing the current collector plate against the bottom surface. Battery manufacturing method.

2. The electrode group also has the recess on the other end side in the axial direction. A method for manufacturing a battery according to claim 1.

3. The radial dimension of the recess from the inner edge is greater than or equal to the depth of the recess. A method for manufacturing a battery according to claim 1 or 2.

4. The process includes winding the electrode plate, whose end corresponding to the recess has been pre-cut, and the separator to form the electrode group, A method for manufacturing a battery according to claim 1 or 2.

5. The electrode plate comprises a current collector and an electrode active material layer laminated on the current collector. The current collector has an exposed portion at one end in the axial direction where the electrode active material layer is not laminated. The recess is formed by cutting away the exposed portion, When removing the exposed portion, the removal includes removing it in such a way that the exposed portion remains. A method for manufacturing a battery according to claim 1 or 2.

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