Secondary battery

Abstract

To provide a highly reliable secondary battery.SOLUTION: One of a first current collector and a second current collector has a first main surface and a through hole or a recess formed in the first main surface, and the other of the first current collector and the second current collector has a second main surface and a protrusion protruding from the second main surface and disposed within the through hole or the recess, and the area of the first current collector located around the through hole or the recess is welded to the second current collector.SELECTED DRAWING: Figure 25

Description

[Technical Field]

[0001] The present technology relates to a secondary battery. [Background technology]

[0002] In a secondary battery, a current collecting structure is provided that is connected to an electrode body housed in a case. An example of a conventional current collecting structure is described in JP 2019-125492 A (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-125492 Summary of the Invention [Problem to be solved by the invention]

[0004] When assembling multiple components to form a current collection structure, it is necessary to improve the reliability of secondary batteries by connecting each component more stably. However, there is still room for improvement in conventional current collection structures.

[0005] An object of the present technology is to provide a highly reliable secondary battery. [Means for solving the problem]

[0006] The present technology provides the following secondary battery.

[0007] [1] A secondary battery comprising: an electrode assembly including a first electrode and a second electrode having a polarity opposite to that of the first electrode; a case accommodating the electrode assembly; and a first electrode terminal electrically connected to the first electrode, wherein the electrode assembly includes a first electrode tab electrically connected to the first electrode, and further includes a current collecting member electrically connecting the first electrode tab and the first electrode terminal, wherein the current collecting member includes a first current collector joined to the first electrode tab and a second current collector joined to the first current collector, wherein the first current collector is electrically connected to the first electrode terminal via the second current collector, wherein one of the first current collector and the second current collector has a first main surface and a through hole or a recess formed in the first main surface, and the other of the first current collector and the second current collector has a second main surface and a protrusion protruding from the second main surface and disposed within the through hole or the recess, and wherein a region of the first current collector positioned around the through hole or the recess is welded to the second current collector.

[0008] [2] The secondary battery according to [1], wherein the second current collector has a plurality of the protrusions spaced apart from each other, and the plurality of the protrusions are arranged within one of the through holes or one of the recesses.

[0009] [3] The secondary battery according to [1] or [2], wherein the first current collector has a thin portion formed around the through hole or the recess, and a thick portion formed at a position farther from the through hole or the recess than the thin portion and having a larger thickness than the thin portion, and the first current collector is welded to the second current collector at the thin portion.

[0010] [4] The secondary battery according to [3], wherein the thin portion is formed so as to reach the outer periphery of the first current collector when viewed from a direction perpendicular to the first main surface.

[0011] [5] The secondary battery according to any one of [1] to [4], further comprising an insulating member provided between the case and the second current collector, the insulating member having an area that does not face the second current collector, and a positioning mechanism for the insulating member and the first current collector being provided in the non-facing area.

[0012] [6] The secondary battery according to any one of [1] to [5], wherein the first current collector and the second current collector are plate-like members whose first and second main surfaces are the widest surfaces, the first current collector and the second current collector are stacked in a thickness direction so that the first and second main surfaces are in contact with each other, and the thickness of the first current collector and the second current collector is 5 mm or less.

[0013] [7] The secondary battery according to any one of [1] to [6], wherein, when viewed from a direction perpendicular to the first main surface, the through holes or the recesses are formed so as to open to the outer peripheral edge of the first current collector.

[0014] [8] The secondary battery according to any one of [1] to [6], wherein, when viewed from a direction perpendicular to the first main surface, at least a portion of the through holes or the recesses has an irregular shape, and the protrusions have portions that follow the irregular shape.

[0015] [9] The secondary battery according to any one of [1] to [6], wherein, when viewed from a direction perpendicular to the first main surface, the through hole or the recess has a shape that does not have an axis of symmetry or a point of symmetry, and the convex portion has a shape similar to the through hole or the recess.

[0016]

[10] The secondary battery according to any one of [1] to [9], wherein the first current collector and the second current collector are made of copper or a copper alloy. [Effects of the Invention]

[0017] According to the present technology, a highly reliable secondary battery can be obtained in which the components in the current collection structure are more stably connected to each other. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 2 is a front view showing the configuration of a secondary battery. [Figure 2] 2 is a diagram showing the secondary battery shown in FIG. 1 as viewed from the direction of arrow II. [Figure 3] 3 is a diagram showing the secondary battery shown in FIG. 1 as viewed from the direction of arrow III. [Figure 4] 4 is a diagram showing the secondary battery shown in FIG. 1 as viewed from the direction of arrow IV. FIG. [Figure 5] 2 is a diagram showing the secondary battery shown in FIG. 1 as viewed from the direction of arrow V. FIG. [Figure 6] FIG. 2 is a front cross-sectional view of the secondary battery shown in FIG. [Figure 7] 8 is a cross-sectional view of the negative electrode (a cross-sectional view taken along line VII-VII in FIG. 8). [Figure 8] FIG. [Figure 9] 11 is a cross-sectional view of the positive electrode (cross-sectional view taken along line IX-IX in FIG. 10). [Figure 10] FIG. [Figure 11] FIG. 2 is a diagram showing the peripheral configuration of a negative electrode current collector. [Figure 12] FIG. 2 is a diagram showing the configuration of the periphery of a positive electrode current collector. [Figure 13] 1 is a flowchart showing a method for manufacturing a secondary battery. [Figure 14] FIG. 2 is a diagram showing a state in which current collectors are joined to a first electrode body and a second electrode body. [Figure 15] FIG. 10 is a view showing a state in which a sealing plate is attached to a negative electrode-side current collector. [Figure 16] FIG. 2 is a diagram showing a state in which the first electrode body and the second electrode body are superimposed. [Figure 17] 10A and 10B are diagrams showing a process of inserting the first electrode body and the second electrode body into the case body. [Figure 18] FIG. 10 is a view showing a state in which a sealing plate is attached to a current collector on the positive electrode side. [Figure 19] FIG. 10 is a view showing a state in which the opening of the case body is sealed. [Figure 20] FIG. 2 is a diagram showing a metal plate constituting a current collector. [Figure 21] FIG. 2 is a perspective view showing the structure of a negative electrode current collector. [Figure 22] FIG. 2 is a view showing a state in which a first current collector has been removed from a negative electrode current collector. [Figure 23] FIG. 2 is a plan view showing a first current collector. [Figure 24] FIG. 4 is a plan view showing a second current collector. [Figure 25] FIG. 2 is a plan view showing a state in which the first current collector and the second current collector are combined. [Figure 26] FIG. 1 is a diagram (part 1) showing an example of a combination of through-holes in a first current collector and protrusions in a second current collector. [Figure 27] FIG. 10 is a diagram (part 2) showing an example of a combination of through-holes in a first current collector and protrusions in a second current collector. [Figure 28] FIG. 10 is a diagram (part 3) showing an example of a combination of through-holes in a first current collector and protrusions in a second current collector. [Figure 29] FIG. 10 is a diagram (part 4) showing an example of a combination of through-holes in a first current collector and protrusions in a second current collector. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, embodiments of the present technology will be described. Note that the same or corresponding parts are denoted by the same reference characters, and description thereof may not be repeated.

[0020] In the embodiments described below, when numbers, amounts, etc. are mentioned, the scope of the present technology is not necessarily limited to those numbers, amounts, etc., unless otherwise specified. Furthermore, in the following embodiments, each component is not necessarily essential to the present technology, unless otherwise specified. Furthermore, the present technology is not necessarily limited to those that achieve all of the effects mentioned in the present embodiments.

[0021] In this specification, the words "comprise," "include," and "have" are open-ended, meaning that when a certain feature is included, other features may or may not be included.

[0022] When geometric terms and terms expressing positional and directional relationships, such as "parallel," "orthogonal," "45° diagonal," "coaxial," and "along" are used in this specification, these terms allow for manufacturing errors and slight variations. When terms expressing relative positional relationships, such as "upper side" and "lower side," are used in this specification, these terms are used to indicate relative positional relationships in a single state, and the relative positional relationships can be reversed or rotated to any angle by changing the installation direction of each mechanism (for example, by turning the entire mechanism upside down).

[0023] In this specification, the term "secondary battery" may include not only lithium ion batteries but also nickel-metal hydride batteries, sodium ion batteries, etc. In this specification, the term "electrode" may collectively refer to positive electrodes and negative electrodes.

[0024] In the drawings, if the electrode body of the secondary battery is a laminated electrode body, the longitudinal direction of the laminated surface is the X direction, and if the electrode body is a wound electrode body, the direction along the winding axis is the X direction. The shorter side direction of the electrode body as viewed from the X direction is the Y direction, and the longer side direction of the electrode body as viewed from the X direction is the Z direction. To facilitate understanding of the invention, the dimensions of each component in the drawings may be slightly different from the actual dimensions.

[0025] In this specification, the X direction may be referred to as the "width direction" of the secondary battery 1, the electrode body 200, and the case body 110, the Z direction may be referred to as the "height direction" of the secondary battery 1, the electrode body 200, and the case body 110, and the Y direction may be referred to as the "thickness direction" of the secondary battery 1, the electrode body 200, and the case body 110.

[0026] (Overall battery configuration) Fig. 1 is a front view of a secondary battery 1 according to an embodiment. Figs. 2 to 5 are views of the secondary battery 1 shown in Fig. 1 as viewed from the directions of arrows II, III, IV, and V, respectively. Fig. 6 is a front cross-sectional view of the secondary battery 1 shown in Fig. 1.

[0027] The secondary battery 1 can be mounted in an electric vehicle (BEV: Battery Electric Vehicle), a plug-in hybrid electric vehicle (PHEV: Plug-in Hybrid Electric Vehicle), a hybrid electric vehicle (HEV: Hybrid Electric Vehicle), etc. However, the use of the secondary battery 1 is not limited to being mounted in a vehicle.

[0028] 1 to 6, the secondary battery 1 includes a case 100, an electrode assembly 200, an electrode terminal 300, and a current collector 400. The case 100 includes a case body 110, a sealing plate 120, and a sealing plate .

[0029] When configuring a battery pack including secondary batteries 1, multiple secondary batteries 1 are arranged in their thickness direction. The arranged secondary batteries 1 may be constrained in the arrangement direction (Y direction) by a constraining member to form a battery module, or the battery pack may be directly supported on the side surface of the battery pack case without using a constraining member.

[0030] The case body 110 is made of a cylindrical, preferably rectangular, member. This results in a rectangular secondary battery 1. The case body 110 is made of metal. Specifically, the case body 110 is made of aluminum, an aluminum alloy, iron, an iron alloy, or the like.

[0031] As shown in Figures 1 and 2, sealing plates 120 and 130 are provided at both ends of case body 110. Case body 110 can be formed into a rectangular tube shape, for example, by abutting the edges of bent plate-like members (joint 115 shown in Figure 2) and joining them together (for example, by laser welding). The corners of the "rectangular tube" may have an R shape. Furthermore, the secondary battery in the present technology is not necessarily limited to a rectangular secondary battery.

[0032] In this embodiment, the case body 110 is formed so that it is longer in the width direction (X direction) of the secondary battery 1 than in the thickness direction (Y direction) and height direction (Z direction) of the secondary battery 1. The dimension (width) of the case body 110 in the X direction is preferably about 30 cm or more. This allows for the construction of a relatively large (high-capacity) secondary battery 1. The dimension (height) of the case body 110 in the Z direction is preferably about 20 cm or less, more preferably about 15 cm or less, and even more preferably about 10 cm or less. This allows for the construction of a relatively low-height secondary battery 1, which improves, for example, the mountability in a vehicle.

[0033] The case main body 110 includes a pair of first side surface portions 111 and a pair of second side surface portions 112. The pair of first side surface portions 111 constitute part of the side surfaces of the case 100. The pair of second side surface portions 112 constitute the bottom surface portion and the top surface portion of the case 100. The pair of first side surface portions 111 and the pair of second side surface portions 112 are arranged to intersect with each other. The pair of first side surface portions 111 and the pair of second side surface portions 112 are connected at their respective ends. Each of the pair of first side surface portions 111 has a larger area than each of the pair of second side surface portions 112.

[0034] 5, a gas release valve 150 is provided on one second side surface portion 112A of the pair of second side surface portions 112. The gas release valve 150 extends in the width direction (X direction) of the secondary battery 1. The gas release valve 150 extends in the X direction from the center of the case body 110 in the X direction but does not reach both ends. The shape of the gas release valve 150 can be changed as appropriate.

[0035] The thickness of the plate-like member in the gas release valve 150 is thinner than the thickness of the plate-like members of the case body 110 other than the gas release valve 150. As a result, when the pressure inside the case 100 reaches or exceeds a predetermined value, the gas release valve 150 breaks preferentially compared to other parts of the case body 110, and releases gas inside the case 100 to the outside.

[0036] 2, a joint 115 is formed on the other second side surface portion 112B of the pair of second side surface portions 112. The joint 115 extends in the width direction (X direction) of the secondary battery 1. At the joint 115, the edges of the plate-like members that make up the case body 110 are joined together.

[0037] 3, an opening 113 (first opening) is provided at the end of case body 110 on the -X side in the X direction. Opening 113 is sealed with sealing plate 120 (first sealing plate). A joint 115 is formed in opening 113 to seal opening 113. Opening 113 and sealing plate 120 have a generally rectangular shape with the Y direction as the short side direction and the Z direction as the long side direction. The generally rectangular shape includes a rectangular shape or a substantially rectangular shape such as a rectangular shape with rounded corners.

[0038] A negative electrode terminal 301 (first electrode terminal) is provided on the sealing plate 120. The position of the negative electrode terminal 301 can be changed as appropriate. The negative electrode terminal 301 is exposed to the outside of the sealing plate 120.

[0039] 4, an opening 114 (second opening) is provided at the end of case body 110 on the +X side in the X direction. Opening 114 is located at the end opposite opening 113, and openings 113 and 114 face each other. Opening 114 is sealed with sealing plate 130 (second sealing plate). A joint 115 is formed in opening 114 to seal opening 114. Opening 114 and sealing plate 130 have a substantially rectangular shape with the Y direction as the short side direction and the Z direction as the long side direction.

[0040] A positive electrode terminal 302 (second electrode terminal) and a liquid injection hole 134 are provided on the sealing plate 130. The positions of the positive electrode terminal 302 and the liquid injection hole 134 can be changed as appropriate.

[0041] The sealing plates 120 and 130 are made of metal. Specifically, the sealing plates 120 and 130 are made of aluminum, an aluminum alloy, iron, an iron alloy, or the like.

[0042] The negative electrode terminal 301 is electrically connected to the negative electrode of the electrode body 200. The negative electrode terminal 301 is attached to the sealing plate 120, i.e., the case 100. The negative electrode terminal 301 is made of a conductive material (more specifically, a metal), and may be made of, for example, copper or a copper alloy. The outer surface of the negative electrode terminal 301 may be provided with a portion or layer made of aluminum or an aluminum alloy. The negative electrode terminal 301 is connected to a plate-shaped member 303.

[0043] The plate-shaped member 303 is located outside the sealing plate 120. The plate-shaped member 303 is arranged so as to fit along the sealing plate 120. The plate-shaped member 303 is conductive. The plate-shaped member 303 is arranged to ensure a connection area with a bus bar or the like that electrically connects the secondary battery 1 to other adjacent secondary batteries. The connection between the negative electrode terminal 301 and the plate-shaped member 303 can be formed by, for example, laser welding.

[0044] The positive electrode terminal 302 is electrically connected to the positive electrode of the electrode assembly 200. The positive electrode terminal 302 is attached to the sealing plate 130, i.e., the case 100. The positive electrode terminal 302 is made of a conductive material (more specifically, a metal), and may be made of, for example, aluminum or an aluminum alloy. The positive electrode terminal 302 is exposed to the outside of the sealing plate 130. The positive electrode terminal 302 is connected to a plate-shaped member 304.

[0045] The plate-shaped member 304 is located outside the sealing plate 130. The plate-shaped member 304 is arranged so as to fit along the sealing plate 130. The plate-shaped member 304 is conductive. The plate-shaped member 304 is arranged to ensure a connection area with a bus bar or the like that electrically connects the secondary battery 1 to other adjacent secondary batteries. The connection between the positive electrode terminal 302 and the plate-shaped member 304 can be formed by, for example, laser welding.

[0046] The liquid inlet hole 134 is sealed with a sealing member (not shown), which may be, for example, a blind rivet or other metal member.

[0047] The electrode assembly 200 is a flat-shaped electrode assembly in which positive electrodes and negative electrodes, which will be described later, are stacked. Specifically, the electrode assembly 200 is a laminated electrode assembly in which multiple positive electrodes and multiple negative electrodes are alternately stacked with a separator (not shown) interposed therebetween. However, in this specification, the term "electrode assembly" is not limited to a laminated electrode assembly, but may also be a wound electrode assembly in which a strip-shaped positive electrode and a strip-shaped negative electrode are wound together with a strip-shaped separator interposed therebetween. The separator may be formed, for example, of a polyolefin microporous film. When the electrode assembly is a laminated electrode assembly including multiple positive electrodes and multiple negative electrodes, the positive electrode tabs provided on each positive electrode may be stacked to form a positive electrode tab group, and the negative electrode tabs provided on each negative electrode may be stacked to form a negative electrode tab group.

[0048] As shown in Fig. 6, the case 100 houses the electrode assembly 200. Fig. 6 illustrates a first electrode assembly 201, which will be described later. The first electrode assembly 201 is housed in the case 100 so that its longitudinal direction is parallel to the X direction.

[0049] Specifically, one or more stacked electrode bodies are housed together with an electrolytic solution (electrolyte) (not shown) inside an insulating sheet (not shown) arranged in the case 100. A solid electrolyte may be used instead of the electrolytic solution.

[0050] The first electrode body 201 includes a substantially rectangular main body, a negative electrode tab group 220, and a positive electrode tab group 250. The negative electrode tab group 220 is located at the end of the main body on the -X side in the X direction. The positive electrode tab group 250 is located at the end of the main body on the +X side in the X direction.

[0051] The negative electrode tab group 220 and the positive electrode tab group 250 are formed so as to protrude from the center portion of the electrode body 200 toward the sealing plate 120 or the sealing plate 130, respectively.

[0052] The current collectors 400 include a negative electrode current collector 400 A and a positive electrode current collector 400 B. The electrode assembly 200 is electrically connected to a negative electrode terminal 301 and a positive electrode terminal 302 via the current collectors 400 .

[0053] The negative electrode current collector 400A is electrically connected to the negative electrode tab group 220 and the negative electrode terminal 301. The negative electrode current collector 400A can be made of a conductive material (more specifically, a metal such as copper or a copper alloy).

[0054] The positive electrode current collector 400B is electrically connected to the positive electrode tab group 250 and the positive electrode terminal 302. The positive electrode current collector 400B can be made of a conductive material (more specifically, a metal such as aluminum or an aluminum alloy).

[0055] (Configuration of electrode body 200) 8, the negative electrode 210 (first electrode) includes a negative electrode core 211 and a negative electrode active material layer 212. The negative electrode core 211 is a copper foil or a copper alloy foil. The negative electrode active material layer 212 is formed by applying a negative electrode active material layer slurry using a die coater.

[0056] A plurality of negative electrode tabs 230 each made of a negative electrode core 211 are provided at one end in the width direction of the negative electrode 210. When the negative electrodes 210 are stacked, the plurality of negative electrode tabs 230 are stacked to form a negative electrode tab group 220. The length in the protruding direction of each of the negative electrode tabs 230 in the plurality of negative electrodes 210 is adjusted as appropriate, taking into consideration the state in which the negative electrode tab group 220 is connected to the negative electrode current collector 400A. The shape of the negative electrode tab 230 is not limited to the example shown in FIG. 8.

[0057] As shown in Fig. 10, the positive electrode 240 (second electrode) has a polarity different from that of the negative electrode 210. The positive electrode 240 includes a positive electrode core 241, a positive electrode active material layer 242, and a positive electrode protective layer 243. The positive electrode core 241 is an aluminum foil or an aluminum alloy foil. The positive electrode active material layer 242 is formed on the positive electrode core 241 by applying a positive electrode active material layer slurry using a die coater.

[0058] A plurality of positive electrode tabs 260 each made of a positive electrode core 241 are provided at one end in the width direction of the positive electrode 240. When the positive electrodes 240 are stacked, the plurality of positive electrode tabs 260 are stacked to form a positive electrode tab group 250. The length of each of the positive electrode tabs 260 in the protruding direction of the plurality of positive electrodes 240 is adjusted as appropriate, taking into consideration the state in which the positive electrode tab group 250 is connected to the positive electrode current collector 400B. The shape of the positive electrode tab 260 is not limited to the example shown in FIG. 10.

[0059] The positive electrode protective layer 243 is provided at the base of the positive electrode tab 260. However, the positive electrode protective layer 243 does not necessarily have to be provided.

[0060] In a typical example, the thickness of the negative electrode tab 230 (one piece) is smaller than the thickness of the positive electrode tab 260 (one piece). In this case, the thickness of the negative electrode tab group 220 is smaller than the thickness of the positive electrode tab group 250.

[0061] (Connection structure between electrode body 200 and current collector 400) 11 and 12, the electrode assembly 200 includes a first electrode assembly 201 and a second electrode assembly 202. Each of the first electrode assembly 201 and the second electrode assembly 202 includes a positive electrode 240 and a negative electrode 210. The electrode assembly 200 may be composed of three or more electrode assemblies.

[0062] The electrode body 200 is formed by stacking a first electrode body 201 and a second electrode body 202. The first electrode body 201 and the second electrode body 202 are aligned in the thickness direction (Y direction) of the first electrode body 201 and the second electrode body 202.

[0063] The first electrode body 201 includes a positive electrode tab group 250 that is arranged at one end of the first electrode body 201 (FIG. 12) and electrically connected to the positive electrode 240, and a negative electrode tab group 220 (first electrode tabs) that is arranged at the other end of the first electrode body 201 (FIG. 11) and electrically connected to the negative electrode 210.

[0064] The second electrode body 202 includes a positive electrode tab group 280 that is arranged at one end of the second electrode body 202 (FIG. 12) and electrically connected to the positive electrode 240, and a negative electrode tab group 270 (second electrode tabs) that is arranged at the other end of the second electrode body 202 (FIG. 11) and electrically connected to the negative electrode 210.

[0065] 11 (negative electrode side structure), the negative electrode tab groups 220, 270 are electrically connected to a current collector 410 (negative electrode current collector 400A). The current collector 410 (first current collector) to which the negative electrode tab groups 220 and 270 are joined can be made of a metal plate-like member. The current collector 410 can also be made of a single member.

[0066] The negative electrode tab group 220 has a curved portion 221. The curved portion 221 is a curved portion of the negative electrode tab group 220. The negative electrode tab group 270 has a curved portion 271. The curved portion 271 is a curved portion of the negative electrode tab group 270.

[0067] Negative electrode tab group 220 and negative electrode tab group 270 are curved in opposite directions so that their leading ends approach each other.

[0068] Furthermore, in the embodiment, the tip portions of the negative electrode tab group 220 and the negative electrode tab group 270 are spaced apart from each other, but the present technology is not limited to this configuration, and the tip portions of the negative electrode tab group 220 and the negative electrode tab group 270 may be in contact with each other.

[0069] The current collector 410 electrically connects the negative electrode terminal 301 to the negative electrode tab group 220 and the negative electrode tab group 270. The current collector 410 has a longitudinal direction in the Z direction and a lateral direction in the Y direction.

[0070] Negative electrode tab group 220 and negative electrode tab group 270 are each joined to current collector 410 at joint 410A (see FIG. 14) described below. Joint 410A can be formed by, for example, ultrasonic bonding, resistance welding, laser welding, caulking, or the like.

[0071] An insulating member 510 is disposed between the plate-shaped member 303 and the sealing plate 120. An insulating member 530 is disposed between the current collector 410 and the sealing plate 120. However, the negative electrode terminal 301 may be electrically connected to the sealing plate 120, and the sealing plate 120 may serve as the negative electrode terminal 301.

[0072] A spacer (not shown) may be disposed between the sealing plate 120 and the main body of the electrode assembly 200 (excluding the negative electrode tab groups 220, 270). The spacer may be made of an insulating resin material. The negative electrode tab groups 220, 270 are protected by passing through the interior of the spacer.

[0073] 12 (structure on the positive electrode side), the positive electrode tab group 250 and the positive electrode tab group 280 are each electrically connected to a current collector 430 (positive electrode current collector 400B). More specifically, the positive electrode tab group 250 is joined to a current collector 431, and the positive electrode tab group 280 is joined to a current collector 432.

[0074] The lengths of the positive electrode tab groups 250, 280 can be changed as appropriate. The lengths of the positive electrode tab groups 250, 280 are preferably the same, but may be different. The lengths of the positive electrode tab groups 250, 280 may be shorter or longer than the negative electrode tab groups 220, 270.

[0075] Current collector 431 to which positive electrode tab group 250 is joined is made of a laminate in which a plurality of metal plates 4300 (see FIG. 20), which will be described later, are stacked. Similarly, current collector 432 to which positive electrode tab group 280 is joined is made of a laminate in which a plurality of metal plates 4300 (see FIG. 20) are stacked. In current collectors 431, 432, the number of stacked metal plates 4300 is two or more, preferably three or more, and more preferably five or more. Furthermore, for example, the number can be 20 or less, preferably 15 or less, and more preferably 10 or less.

[0076] The current collectors 431 and 432 electrically connect the positive electrode terminal 302 to the positive electrode tab group 250 and the positive electrode tab group 280. The current collectors 431 and 432 are each joined to the current collector 420 in a folded state, and are electrically connected to the positive electrode terminal 302.

[0077] A more stable current collection structure can be configured by dividing the current collector 430 into two current collectors 431 and 432. However, the scope of the present technology is not limited to this, and, for example, the positive electrode tab group 250 and the positive electrode tab group 280 may be joined to one current collector 430. By joining the positive electrode tab group 250 and the positive electrode tab group 280 to one current collector 430, the joining process can be simplified (reduced in number of times).

[0078] 12 , the current collectors 431 and 432 are joined to the current collector 420 at a portion where the current collectors 431 and 432 overlap each other (joint portion 420A in FIG. 18 ). However, the scope of the present technology is not limited thereto, and the current collectors 431 and 432 may be joined to the current collector 420 at positions spaced apart or adjacent to each other on the current collector 420.

[0079] Positive electrode tab group 250 and positive electrode tab group 280 are respectively joined to current collectors 431 and 432 at joints 431A and 432A (see FIG. 14) described below. Joints 431A and 432A can be formed by, for example, ultrasonic bonding, resistance welding, laser welding, caulking, or the like.

[0080] Joint portion 431A between current collector 431 and positive electrode tab group 250 and joint portion 432A between current collector 432 and positive electrode tab group 280 are formed at positions spaced apart from each other on the XY plane.

[0081] 12 , a positive electrode tab group 250 is disposed in the X direction between the end of the current collector 431 on the electrode body 200 side (left side in the figure) and the end of the current collector 432 on the electrode body 200 side (left side in the figure) (the gap between the current collectors 431, 432). A positive electrode tab group 280 may be disposed in the gap between the current collectors 431, 432, or both the positive electrode tab groups 250, 280 may be disposed in the gap between the current collectors 431, 432. This allows the gap between the current collectors 431, 432 to be used effectively.

[0082] An insulating member 520 is disposed between the plate-shaped member 304 and the sealing plate 130. An insulating member 540 is disposed between the positive electrode terminal 302 and the sealing plate 130. However, the positive electrode terminal 302 may be electrically connected to the sealing plate 130, and the sealing plate 130 may serve as the positive electrode terminal 302.

[0083] A spacer (not shown) may be disposed between the sealing plate 130 and the main body of the electrode assembly 200 (excluding the positive electrode tab groups 250, 280). The spacer may be made of an insulating resin material. The positive electrode tab groups 250, 280 are protected by passing through the interior of the spacer.

[0084] (Manufacturing process of secondary battery 1) A method for manufacturing the secondary battery according to this embodiment will now be described. Fig. 13 is a flowchart showing the method for manufacturing the secondary battery 1.

[0085] As shown in FIG. 13, the method for manufacturing the secondary battery 1 includes a step (S1) of preparing the first electrode body 201 and the second electrode body 202, a step (S2) of joining the negative electrode tab group 220 and the negative electrode tab group 270 to the current collector 410, a step (S3) of joining the positive electrode tab group 250 to the current collector 431, a step (S4) of joining the positive electrode tab group 280 to the current collector 432, a step (S5) of electrically connecting the current collector 410 joined to the negative electrode tab group 220 and the negative electrode tab group 270 to the negative electrode terminal 301, and a step (S6) of electrically connecting the first electrode body 201 and the second electrode body 202 to the negative electrode tab group 220. The process includes a step (S6) of overlapping the first electrode body 201 and the second electrode body 202, a step (S7) of assembling a spacer and an insulating sheet to the electrode body 200, a step (S8) of inserting the first electrode body 201 and the second electrode body 202 into the case body 110, a step (S9) of electrically connecting the current collectors 431, 432 joined to the positive electrode tab groups 250, 280 to the positive electrode terminal 302, a step (S10) of joining the sealing plates 120, 130 to the case body 110 to seal the openings 113, 114, and a step (S11) of conducting a leak test.

[0086] 14 to 19 are diagrams showing the steps in the method for manufacturing the secondary battery 1. FIG.

[0087] In the step (S1) of producing the first electrode body 201 and the second electrode body 202, it is preferable that a portion of the tip of each of the negative electrode tab group 220, the positive electrode tab group 250, the negative electrode tab group 270, and the positive electrode tab group 280 is cut off so that the lengths of the tips are the same when bundled.

[0088] As shown in FIG. 14, after the first electrode body 201 and the second electrode body 202 are fabricated, the negative electrode tab groups 220, 270 are joined to the current collector 410 (S2), the positive electrode tab group 250 is joined to the current collector 431 (S3), and the positive electrode tab group 280 is joined to the current collector 432 (S4).

[0089] The negative electrode tab groups 220 and 270 are joined to the current collector 410 at a joint 410A. The positive electrode tab group 250 is joined to the current collector 431 at a joint 431A. The positive electrode tab group 280 is joined to the current collector 432 at a joint 432A.

[0090] The current collector 431, the first electrode body 201, the current collector 410, the second electrode body 202, and the current collector 432 are arranged in this order in the direction of the arrow DR1.

[0091] 14 , in the height direction of the first electrode body 201 and the second electrode body 202, the current collector 410 and the current collectors 431, 432 are arranged to be biased to one side from the center of the first electrode body 201 and the second electrode body 202. In addition, in the height direction of the first electrode body 201 and the second electrode body 202, the negative electrode tab group 220, the positive electrode tab group 250, the negative electrode tab group 270, and the positive electrode tab group 280 are each arranged to be biased to one side from the center of the first electrode body 201 and the second electrode body 202.

[0092] However, the scope of the present technology is not limited thereto, and the current collector 410 and the current collectors 431, 432 may be disposed at the center of the first electrode body 201 and the second electrode body 202 in the height direction of the first electrode body 201 and the second electrode body 202. Furthermore, the negative electrode tab group 220, the positive electrode tab group 250, the negative electrode tab group 270, and the positive electrode tab group 280 may each be disposed at the center of the first electrode body 201 and the second electrode body 202 in the height direction of the first electrode body 201 and the second electrode body 202.

[0093] As shown in FIG. 15 , the current collector 410 joined to the negative electrode tab group 220 and the negative electrode tab group 270 is assembled to the sealing plate 120. A current collector 440 (second current collector) and a negative electrode terminal 301 are attached to the sealing plate 120 in advance. The current collector 410 is assembled to the sealing plate 120 via the current collector 440. The current collector 410 is joined to the current collector 440 at a joint 440A. The joint 440A can be formed by, for example, laser welding or the like. As a result of the above, the current collector 410 is electrically connected to the negative electrode terminal 301 (S5).

[0094] 16, the negative electrode tab group 220 and the negative electrode tab group 270 are folded in the thickness direction of the first electrode body 201 and the second electrode body 202 (a direction perpendicular to the DR1 direction in FIGS. 14 and 15), and the first electrode body 201 and the second electrode body 202 are overlapped (S6). Here, the negative electrode tab group 220 and the negative electrode tab group 270 are folded so that their leading ends face each other.

[0095] When the first electrode body 201 and the second electrode body 202 are "superimposed", the first electrode body 201 and the second electrode body 202 may be directly superimposed on each other, or another member may be disposed between the first electrode body 201 and the second electrode body 202. Furthermore, the first electrode body 201 and the second electrode body 202 may or may not be fixed by tape or the like.

[0096] The above-mentioned spacer and insulating sheet are assembled to the electrode assembly 200 (S7). However, the spacer and insulating sheet are not necessarily required components in the present technology. The insulating sheet does not necessarily need to cover the entire surface of the electrode assembly 200. When the electrode assembly 200 is covered with the insulating sheet, it is preferable that the spacer is also covered with the insulating sheet.

[0097] As shown in FIG. 17, the first electrode body 201 and the second electrode body 202 stacked on top of each other are inserted into the case body 110 with the current collector 430 side at the top (S8).

[0098] When inserting the electrode assembly 200 into the case body 110, the electrode assembly 200 may be pulled from the positive electrode side or pushed from the negative electrode side. When the electrode assembly 200 is pushed from the negative electrode side, the negative electrode tab group 220 and the negative electrode tab group 270 can be bent at the same time.

[0099] As shown in FIG. 18 , after the electrode assembly 200 is inserted into the case body 110, the current collector 430 joined to the positive electrode tab group 250 and the positive electrode tab group 280 is assembled to the sealing plate 130. The current collector 420 and the positive electrode terminal 302 are attached to the sealing plate 130 in advance. The current collector 430 is assembled to the sealing plate 130 via the current collector 420. The current collector 410 is joined to the current collector 420 at a joint 420A. The joint 420A can be formed by, for example, laser welding or the like. As a result of the above, the current collector 430 is electrically connected to the positive electrode terminal 302 (S9).

[0100] The current collectors 431, 432 joined to the positive electrode tab groups 250, 280 are electrically connected to the positive electrode terminal 302, and then bent together with the positive electrode tab groups 250, 280 into the shape shown in Fig. 12. It is preferable that the current collectors 431, 432 are bent simultaneously, but the current collectors 431, 432 may be bent sequentially.

[0101] 19, sealing plates 120 and 130 are joined to case body 110 (S10). Sealing plate 120 seals opening 113 of case body 110, and sealing plate 130 seals opening 114 of case body 110. In this way, first electrode body 201 and second electrode body 202 are housed in case 100.

[0102] After the above steps are completed, inspections such as a leak inspection are performed (S11). After the leak inspection, the secondary battery 1 is dried to remove moisture from inside the case 100. Then, electrolyte is injected into the inside of the case 100 through the liquid injection hole 134. When injecting the electrolyte, the case 100 is tilted with the sealing plate 130 facing up and the sealing plate 120 facing down, and the electrolyte is injected into the inside of the case 100 through the liquid injection hole 134 in the sealing plate 130. Then, degassing charging is performed. The liquid injection hole 134 may be temporarily sealed during degassing charging. The liquid injection hole 134 is then sealed, and the secondary battery 1 is completed.

[0103] The order of the electrode assembly 200 insertion step and the current collector connection step is not limited to the above example. For example, the order of the current collectors 410, 431, and 432 joining steps (S2 to S4) can be changed as appropriate.

[0104] In this embodiment, an example has been described in which, after the step (S8) of inserting the first electrode body 201 and the second electrode body 202 into the case 100 body is completed, the current collector 430 is electrically connected (S9) to the positive electrode terminal 302 with the first electrode body 201 and the second electrode body 202 completely positioned within the case body 110; however, the positive electrode terminal 302 and the electrode body 200 may also be electrically connected (S9) before the step (S8) of inserting the electrode body 200 into the case body 110 is completely completed (during the insertion step).

[0105] In this embodiment, an example has been described in which the current collectors 431, 432 are bent after the step (S9) of electrically connecting the current collectors 431, 432 to the positive electrode terminal 302, but the current collectors 431, 432 may be deformed before the step (S9) of electrically connecting the current collectors 431, 432 to the positive electrode terminal 302.

[0106] (Configuration of metal plate 4300) As shown in FIG. 20, the metal plate 4300 includes a first region 430A joined to the positive electrode tab groups 250, 280, a second region 430B joined to the current collector 420, and a connection portion 430C, a hole portion 430D, and a notch 430E provided between the first region 430A and the second region 430B.

[0107] When forming the current collector 430, the plurality of metal plates 4300 may be bonded to one another in the first region 430A and the second region 430B. The bonding of the plurality of metal plates 4300 is preferably performed by, for example, ultrasonic bonding, diffusion bonding, or the like. In the case of diffusion bonding, the metal plates 4300 are preferably bonded to one another by applying pressure to the stacked metal plates 4300 while being heated at a temperature lower than the melting point of the metal plates 4300. The bonding of the plurality of metal plates 4300 to one another is performed before other conductive members (positive electrode tab groups 250, 280 and the current collector 420) are bonded to the first region 430A and the second region 430B.

[0108] It is preferable that the connection portion 430C of the current collector 430 includes a region where the multiple metal plates 4300 are not joined to one another. This makes it easier to bend the current collector 430 at the connection portion 430C. It is preferable that the bent portion of the metal plate 4300 includes a region where the multiple metal plates 4300 are not joined to one another. It is also preferable that the multiple metal plates 4300 are not joined to one another over the entire bent portion of the metal plate 4300. There may also be portions in which the multiple metal plates 4300 are not joined to one another in regions other than the connection portion 430C (the first region 430A and the second region 430B).

[0109] In regions where the metal plates 4300 are not joined to each other, the metal plates 4300 may abut against each other. Also, a small gap may exist between the metal plates 4300. In regions where the metal plates 4300 are not joined to each other, the metal plates 4300 are not welded to each other, and a clear boundary exists between each metal plate 4300. For example, a natural oxide film may exist on the surface of each metal plate 4300.

[0110] By providing hole 430D and notch 430E in connection portion 430C, the cross-sectional area of ​​connection portion 430C can be reduced, making it easier to bend current collector 430 at connection portion 430C. Connection portion 430C can also function as a fuse portion.

[0111] Metal plate 4300 can be made of, for example, aluminum or an aluminum alloy. The thickness of one metal plate 4300 is preferably greater than the thickness of one positive electrode tab 260, and is preferably about three times or more (more preferably about five times or more) the thickness of one positive electrode tab 260.

[0112] (Structure of negative electrode current collector 400A) Next, the structure of the negative electrode current collector 400A will be described with reference to FIGS.

[0113] 21 to 25, the current collectors 410 and 440 constituting the negative electrode current collector 400A are each made of a plate-like member and are arranged on an insulating member 530, stacked in the thickness direction so that their respective main surfaces (first and second main surfaces) face each other. The thickness of the current collector 410 (thick portion 410C) and the current collector 440 is preferably about 5 mm or less (more preferably about 2 mm or less). However, the current collectors 410 and 440 according to the present technology may have an L-shape formed by bending a plate-like member.

[0114] As shown in FIGS. 21 and 23, a main surface of current collector 410 is formed with thin portion 410B, which has a relatively small thickness, and thick portion 410C, which is thicker than thin portion 410B. When viewed in the thickness direction of current collector 410 (a direction perpendicular to the first main surface), thin portion 410B is formed so as to reach the outer periphery of current collector 410. Thin portion 410B has through-holes 411 formed therein, which extend in a direction perpendicular to the plane of FIG. 23. The thickness of thin portion 410B is preferably approximately 0.1 mm or more, more preferably approximately 0.3 mm or more, and even more preferably approximately 0.5 mm or more. The thickness of thin portion 410B is preferably approximately 2 mm or less, more preferably approximately 1 mm or less, and even more preferably approximately 0.7 mm or less.

[0115] A step is provided between thin portion 410B and thick portion 410C. A protrusion 412 that protrudes toward insulating member 530 is formed at the end of thick portion 410C that is away from thin portion 410B.

[0116] 22 and 24, a through-hole 441 and a protrusion 442 are formed on the main surface of the current collector 440. The negative electrode terminal 301 is inserted into the through-hole 441. The protrusion 442 protrudes in a direction perpendicular to the paper surface of FIG. 24 (toward the viewer).

[0117] 25, when current collectors 410 and 440 are stacked, convex portions 442 of current collector 440 are disposed within through-holes 411 of current collector 410. This engagement prevents misalignment between current collectors 410 and 440. A fitting gap may be formed between convex portions 442 and through-holes 411. This fitting gap (shortest distance) is preferably about 1.0 mm or less, and more preferably about 0.5 mm or less.

[0118] 25, multiple (two) protrusions 442 spaced apart from each other are arranged in one through-hole 411. This makes it possible to suppress relative rotation between the current collectors 410 and 440. Furthermore, compared to the case where there is only one protrusion 442 with a relatively large diameter, it is possible to more easily fit the through-hole 411 and the protrusion 442.

[0119] The current collectors 410, 440 are welded to each other at a joint 440A located around the through hole 411 into which the protrusion 442 is inserted. More specifically, the joint 440A (laser welded portion) is formed on the thin portion 410B together with the through hole 411. The joint 440A extends linearly so as to be approximately parallel to the longitudinal direction of the through hole 411. Two joints 440A are formed in the lateral direction of the through hole 411 so as to sandwich the through hole 411 from both sides. Note that the formation form of the joint 440A is not limited to this.

[0120] Joint 440A is provided near through-hole 411. More specifically, joint 440A is arranged so as to form a gap of about 0.1 mm or more (more preferably about 0.3 mm or more, and even more preferably about 0.5 mm or more) and about 5 mm or less (more preferably about 3 mm or less) between joint 440A and the outer edge of through-hole 411.

[0121] As shown in FIG. 22 , insulating member 530 has region 531 that does not face current collector 440 and recessed portion 532 provided in region 531. Region 531 directly faces current collector 410. Note that through-holes may be provided instead of recessed portion 532. When current collectors 410 and 440 are assembled on insulating member 530, protrusions 412 of current collector 410 are disposed within recessed portion 532 of insulating member 530. The recessed portion 532 and protrusions 412 fit together to form a positioning mechanism that prevents misalignment between insulating member 530 and current collector 410. This allows current collectors 410 and 440 to be more stably positioned, resulting in more stable formation of joint 440A. Furthermore, even if shock or vibration is applied during use of the secondary battery, local stress on joint 440A can be more effectively prevented, thereby preventing damage to joint 440A.

[0122] 26 to 29, the shapes of through-hole 411 of current collector 410 and convex portion 442 of current collector 440 will be described. Figures 26 to 29 show through-hole 411 and convex portion 442 viewed from the protruding direction of convex portion 442.

[0123] 26, circular through-holes 411 and protrusions 442 are formed. According to the example shown in Fig. 26, it is easy to form through-holes 411 and protrusions 442. Furthermore, it is possible to suppress positional deviation evenly in all directions.

[0124] 27, rectangular through-hole 411 and protrusion 442 are formed. Through-hole 411 and protrusion 442 have similar shapes. According to the example shown in FIG. 27, the relative rotation of current collectors 410, 440 can be suppressed by simply forming one protrusion 442. Furthermore, when the current collectors 410, 440 are misaligned relative to each other, the inner wall of through-hole 411 and the side wall of protrusion 442 come into surface contact with each other, thereby suppressing an increase in local load and making it possible to suppress damage to joint 440A formed on current collectors 410, 440.

[0125] In the example of Fig. 28, through-hole 411 has an irregular shape. That is, through-hole 411 has a shape without an axis of symmetry or a point of symmetry (it is neither line-symmetric nor point-symmetric). Furthermore, protrusion 442 has a shape that follows the irregular shape of through-hole 411. According to the example shown in Fig. 28, one through-hole 411 and one protrusion 442 can perform positioning in multiple directions and restrict rotation. Furthermore, it is possible to prevent assembly errors when assembling current collectors 410 and 440.

[0126] 29, through-hole 411 is formed to open at the outer periphery of current collector 410. According to the example of Fig. 29, since the side of through-hole 411 is open, current collectors 410 and 440 can be slid relative to each other to fit through-hole 411 and protrusion 442 together.

[0127] In this specification, a hole with a partially open side, as in Figure 29, is also referred to as a "through hole" or a "recess." In addition, a combination of the examples shown in Figures 26 to 29 may be applied.

[0128] In the present embodiment, misalignment between multiple members in the current collecting structure can be suppressed by fitting through-hole 411 of current collector 410 into protrusion 442 of current collector 440. This allows current collector 410 and current collector 440 to be stably connected, forming joint 440A with higher reliability.

[0129] By providing through-hole 411 on the current collector 410 side, when current collectors 410 and 440 are combined, it is possible to visually confirm the state in which protrusion 442 is arranged in through-hole 411. Furthermore, the state in which current collector 410 and current collector 440 are in contact with each other can also be confirmed through through-hole 411.

[0130] Furthermore, by arranging the joint 440A near the through hole 411 that suppresses misalignment of the current collectors 410, 440, the joint 440A can be formed in an area where the relative amount of misalignment of the current collectors 410, 440 is small, thereby improving the reliability of the welded joint at the joint 440A and, as a result, improving the reliability of the secondary battery 1.

[0131] Furthermore, by arranging joint portion 440A in thin portion 410B of current collector 410, laser welding can be performed with a relatively low output, which can suppress the generation of spatter and the resulting damage to surrounding components.

[0132] Furthermore, by providing thin portion 410B and thick portion 410C on one side of current collector 410, it becomes easy to determine the front and back of current collector 410, thereby improving the efficiency of the assembly process of current collectors 410, 440. By forming thin portion 410B so as to reach the outer edge of current collector 410, it becomes easy to mold current collector 410 including thin portion 410B.

[0133] When current collectors 410, 440 are made of copper or a copper alloy, it is particularly necessary to improve the reliability of the welded joint at joint 440A. In this case, the effect of suppressing misalignment of current collectors 410, 440 and insulating member 530 is particularly significant. However, current collectors 410, 440 may be made of conductive members (preferably metal members), and the present technology does not limit their material to copper or a copper alloy.

[0134] Furthermore, by configuring the current collectors 410, 440 with plate-like members having a thickness of a predetermined value or less (approximately 5 mm or less or approximately 2 mm or less), it is possible to reduce the space occupied by the negative electrode current collector 400A in the thickness direction (X direction) of the current collectors 410, 440. As a result, the energy density of the secondary battery 1 is improved.

[0135] Furthermore, in the present embodiment, by using current collector 430 formed of a laminate of multiple metal plates 4300, it is possible to provide current collector 430 that can be easily and stably deformed while suppressing an increase in resistance. As a result, positive electrode current collector 400B can be made smaller, and the energy density of secondary battery 1 can be improved.

[0136] In the present embodiment, in the step (S2) of joining the current collector 410 to the negative electrode tab groups 220, 270, the first electrode body 201 is placed on one side of the current collector 410, and the second electrode body 202 is placed on the other side of the current collector 410, as shown in FIG. 14 , the negative electrode tab groups 220, 270 are joined to the current collector 410 in this state. In this state, the main bodies of the first electrode body 201 and the second electrode body 202 are positioned relatively far from the current collector 410, which provides many options for joining techniques and also allows the negative electrode tab groups 220, 270 to be made relatively short. By shortening the negative electrode tab groups 220, 270, the internal space of the case 100 can be effectively utilized, further improving the energy density of the secondary battery 1.

[0137] Furthermore, in the present embodiment, current collector 431 and current collector 432 are curved in the same direction when first electrode body 201 and second electrode body 202 are stacked together, so it is possible to arrange current collector 432 by efficiently utilizing the space on the inner periphery of the curved portion of current collector 431. As a result, positive electrode collector 400B can be further miniaturized, and the energy density of secondary battery 1 can be improved.

[0138] Furthermore, in the present embodiment, by joining the current collectors 431, 432 to the positive electrode tab groups 250, 280 in advance (S3, S4), it is possible to protect the positive electrode tab groups 250, 280 and suppress damage thereto (deformation, breakage, etc.) in the subsequent step (S6) of stacking the first electrode body 201 and the second electrode body 202 and the step (S8) of inserting the first electrode body 201 and the second electrode body 202 into the case body 110. As a result, it is possible to provide a highly reliable secondary battery 1.

[0139] (supplement) In the present embodiment, an example has been described in which a folded current collector 430 made of a metal plate laminate is used on the positive electrode side (FIG. 12) and a current collector 410 made of a single metal member is used on the negative electrode side (FIG. 11). However, the scope of the present technology is not limited to this, and the same structure as that on the negative electrode side may be adopted on the positive electrode side, or structures opposite to those described above may be adopted on the positive electrode side and the negative electrode side.

[0140] A recess with a bottom may be provided instead of the through-hole 411 (current collector 410) of this embodiment, and a through-hole may be provided instead of the recess 532 (insulating member 530) of this embodiment.

[0141] In the present embodiment, an example has been described in which through-holes 411 are provided in current collector 410 and convex portions 442 are provided in current collector 440, but these may be reversed, and a structure may be adopted in which convex portions are provided in current collector 410 and through-holes or concave portions are provided in current collector 440.

[0142] Similarly, instead of the convex portions 412 of the current collector 410 and the concave portions 532 of the insulating member 530, the current collector 410 may be provided with concave portions and the insulating member 530 may be provided with convex portions.

[0143] In this embodiment, an example has been described in which two negative electrode tab groups 220, 270 are joined to the current collector 410, but the number of electrode tab groups joined to the current collector 410 is not limited to two, and may be one, or three or more.

[0144] In the present embodiment, an example has been described in which an electrode tab group in which a plurality of electrode tabs are stacked is joined to a current collector, but the scope of the present technology is not limited to this, and a configuration in which a single electrode tab is joined to a current collector may also be used.

[0145] Although the embodiments of the present technology have been described above, the embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present technology is defined by the claims, and it is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0146] 1 secondary battery, 100 case, 110 case body, 111 first side portion, 112, 112A, 112B second side portion, 113, 114 opening, 115 joint portion, 120, 130 sealing plate, 134 liquid injection hole, 150 gas release valve, 200 electrode body, 201 first electrode body, 202 second electrode body, 210 negative electrode, 211 negative electrode core body, 212 negative electrode active material layer, 220 negative electrode tab group, 221 curved portion, 230 negative electrode tab, 240 positive electrode, 241 positive electrode core body, 242 positive electrode active material layer, 243 positive electrode protective layer, 250 positive electrode tab group, 260 positive electrode tab, 270 negative electrode tab group, 271 curved portion, 280 positive electrode tab group, 300 Electrode terminal, 301 negative electrode terminal, 302 positive electrode terminal, 303, 304 plate-shaped member, 400, 410, 420, 430, 431, 432, 440 current collector, 400A negative electrode collector, 400B positive electrode collector, 410A joint portion, 410B thin portion, 410C thick portion, 411, 441 through hole, 412, 442 convex portion, 420A, 431A, 432A, 440A joint portion, 430A first region, 430B second region, 430C connection portion, 430D hole portion, 510, 520, 530, 540 insulating member, 531 region, 532 concave portion, 4300 metal plate.

Claims

1. an electrode body including a first electrode and a second electrode having a polarity different from that of the first electrode; a case for accommodating the electrode assembly; a first electrode terminal electrically connected to the first electrode, the electrode body includes a first electrode tab electrically connected to the first electrode; a current collecting member electrically connecting the first electrode tab and the first electrode terminal; the current collecting member includes a first current collector joined to the first electrode tab and a second current collector joined to the first current collector, the first current collector is electrically connected to the first electrode terminal via the second current collector; one of the first current collector and the second current collector has a first main surface and a through-hole or a recess formed in the first main surface; the other of the first current collector and the second current collector has a second main surface and a protrusion protruding from the second main surface and disposed within the through hole or the recess, a region of the first current collector positioned around the through hole or the recess is welded to the second current collector.

2. the second current collector has a plurality of the protrusions spaced apart from one another, The secondary battery according to claim 1 , wherein a plurality of the protrusions are arranged in one of the through-holes or one of the recesses.

3. the first current collector has a thin portion formed around the through hole or the recess, and a thick portion that is formed at a position farther from the through hole or the recess than the thin portion and has a thickness greater than that of the thin portion, 3. The secondary battery according to claim 1, wherein the first current collector is joined to the second current collector by welding in the thin-walled portion.

4. The secondary battery according to claim 3 , wherein the thin portion is formed so as to reach an outer periphery of the first current collector when viewed from a direction perpendicular to the first main surface.

5. an insulating member provided between the case and the second current collector; the insulating member has a region that does not face the second current collector, The secondary battery according to claim 1 , wherein a positioning mechanism for positioning the insulating member and the first current collector is provided in the non-opposing region.

6. the first current collector and the second current collector are plate-like members, the first main surface and the second main surface of which are the widest surfaces, respectively; the first current collector and the second current collector are stacked in a thickness direction such that the first main surface and the second main surface are in contact with each other, 3. The secondary battery according to claim 1, wherein the first current collector and the second current collector have a thickness of 5 mm or less.

7. 3. The secondary battery according to claim 1, wherein the through-hole or the recess is formed so as to open to an outer periphery of the first current collector when viewed from a direction perpendicular to the first main surface.

8. 3. The secondary battery according to claim 1, wherein when viewed from a direction perpendicular to the first main surface, at least a portion of the through hole or the recess has an irregular shape, and the protrusion has a portion that follows the irregular shape.

9. 3. The secondary battery according to claim 1, wherein, when viewed from a direction perpendicular to the first main surface, the through hole or the recess has a shape that does not have an axis of symmetry or a point of symmetry, and the convex portion has a shape similar to the through hole or the recess.

10. 3. The secondary battery according to claim 1, wherein the first current collector and the second current collector are made of copper or a copper alloy.

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