Secondary battery and manufacturing method thereof

Abstract

To provide a highly reliable secondary battery and a manufacturing method thereof.SOLUTION: A secondary battery includes an electrode body including a first electrode, a second electrode having a polarity different from that of the first electrode, and an electrode tab electrically connected to the first electrode, a case for accommodating the electrode body; a current collector consisting of a stack of multiple metal plates electrically connected to the electrode tab, another conductive member connected to the current collector, and a metal member having a length, width, or thickness different from each of the multiple metal plates in the current collector, and joined to the other conductive member together with the current collector.SELECTED DRAWING: Figure 16

Description

[Technical Field]

[0001] The present technology relates to a secondary battery and a manufacturing method thereof. [Background technology]

[0002] Japanese Patent No. 5337586 (Patent Document 1) and Japanese Patent No. 4120353 (Patent Document 2) disclose current collectors made of a laminate of metal plates. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5337586 [Patent Document 2] Patent No. 4120353 Summary of the Invention [Problem to be solved by the invention]

[0004] When a current collector and another conductive member are melted and joined together, it is necessary to prevent gaps from being generated at the joint due to differences in the solidification rates of the two.

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

[0006] The present technology provides the following secondary battery and method for manufacturing the same.

[0007] [1] A secondary battery comprising: an electrode assembly including a first electrode, a second electrode having a polarity different from that of the first electrode, and an electrode tab electrically connected to the first electrode; a case for accommodating the electrode assembly; a current collector made of a laminate of multiple metal plates electrically connected to the electrode tab; another conductive member connected to the current collector; and a metal member having a length, width, or thickness different from that of each of the multiple metal plates in the current collector, and joined to the other conductive member together with the current collector.

[0008] [2] The secondary battery described in [1], wherein the current collector includes a first region, a second region, and a folded portion, the electrode tab is joined to the first region, the other conductive member is joined to the second region, and the folded portion is disposed between the first region and the second region.

[0009] [3] The secondary battery according to [1] or [2], wherein the current collector has a first surface facing the other conductive member and a second surface located opposite the first surface, and the metal members are disposed on the first surface and the second surface.

[0010] [4] The secondary battery according to any one of [1] to [3], wherein the current collector includes at least a first bonding region where the plurality of metal plates are bonded together and do not reach the other conductive members, and a second bonding region where the current collector, the metal member, and the other conductive members are bonded to each other.

[0011] [5] The secondary battery according to [4], wherein the area of ​​the second bonding region is smaller than the area of ​​the first bonding region when viewed from the stacking direction of the plurality of metal plates.

[0012] [6] The secondary battery according to [4] or [5], wherein the first bonding region and the second bonding region overlap when viewed from the stacking direction of the plurality of metal plates.

[0013] [7] The secondary battery according to [4] or [5], wherein the first bonding region and the second bonding region are spaced apart when viewed from the stacking direction of the plurality of metal plates.

[0014] [8] A secondary battery described in any one of [1] to [7], wherein the thickness of one of the plurality of metal plates is greater than the thickness of one of the electrode tabs, and the thickness of the metal member is greater than the thickness of one of the plurality of metal plates.

[0015] [9] The secondary battery according to any one of [1] to [8], wherein a first tab group and a second tab group each including a plurality of the electrode tabs are provided, two current collectors are provided, one current collector is connected to the first tab group, and the other current collector is connected to the second tab group, and the two current collectors are stacked and joined to the other conductive member together with the metal member.

[0016]

[10] A method for manufacturing a secondary battery comprising: an electrode assembly including a first electrode, a second electrode having a polarity different from that of the first electrode, and an electrode tab electrically connected to the first electrode; a case for accommodating the electrode assembly; a current collector formed of a stack of multiple metal plates; another conductive member connected to the current collector; and a metal member having a length, width, or thickness different from that of each of the multiple metal plates in the current collector and joined to the other conductive member together with the current collector, the method comprising the steps of: joining the electrode tab to the current collector; and joining the current collector and the metal member to the other conductive member by irradiating a high-energy ray to a portion where the current collector and the metal member are overlapped.

[0017]

[11] The method for manufacturing a secondary battery according to

[10] , further comprising the step of bending the current collector after joining the current collector and the metal member to the other conductive member.

[0018]

[12] The method for manufacturing a secondary battery according to

[10] or

[11] , further comprising a step of joining the plurality of metal plates in the current collector to each other, in which the electrode tab is joined to the current collector after the plurality of metal plates are joined to each other.

[0019]

[13] The method for manufacturing a secondary battery according to any one of

[10] to

[12] , wherein the current collector has a first surface facing the other conductive member and a second surface located opposite the first surface, and the metal member is placed on at least one of the first surface and the second surface, and high-energy rays are irradiated to the portion where the metal member is placed, thereby joining the current collector and the metal member to the other conductive member.

[0020]

[14] The method for manufacturing a secondary battery according to any one of

[10] to

[13] , further comprising a step of joining the plurality of metal plates in the current collector to each other, wherein after the plurality of metal plates are joined to each other, high-energy rays are irradiated to an area where the plurality of metal plates are not joined to each other, thereby joining the current collector and the metal member to the other conductive member.

[0021]

[15] The method for manufacturing a secondary battery according to any one of

[10] to

[13] , further comprising a step of joining the plurality of metal plates in the current collector to each other, in which after the plurality of metal plates are joined to each other, a high-energy ray is irradiated onto the area where the plurality of metal plates are joined to each other, thereby joining the current collector and the metal member to the other conductive member. [Effects of the Invention]

[0022] According to the present technology, it is possible to provide a highly reliable secondary battery and a method for manufacturing the same. [Brief explanation of the drawings]

[0023] [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] 10A and 10B are diagrams showing modified examples of the peripheral configuration of the negative electrode current collector. [Figure 14] 1 is a flowchart showing a method for manufacturing a secondary battery. [Figure 15] 10A and 10B are plan views showing examples of the joining structure between the laminated current collector and another conductive member. [Figure 16] FIG. 1 is a cross-sectional view (part 1) showing an example of a joint structure between a laminated current collector and another conductive member. [Figure 17] FIG. 2 is a cross-sectional view (part 2) showing an example of a joint structure between a laminated current collector and another conductive member. [Figure 18] FIG. 10 is a cross-sectional view (part 3) showing an example of a joint structure between a laminated current collector and another conductive member. [Figure 19] FIG. 10 is a cross-sectional view (part 4) showing an example of a joint structure between a laminated current collector and another conductive member. [Figure 20] FIG. 5 is a cross-sectional view (part 5) showing an example of a joint structure between a laminated current collector and another conductive member. [Figure 21] FIG. 21 is a plan view showing the example of the joint structure shown in FIG. 20. [Figure 22] FIG. 6 is a cross-sectional view (part 6) showing an example of a joint structure between a laminated current collector and another conductive member. [Figure 23] 10A and 10B are plan views showing examples of the joining structure between the laminated current collector and another conductive member. [Figure 24]FIG. 10 is a cross-sectional view (part 7) showing an example of a joint structure between a laminated current collector and another conductive member. [Figure 25] FIG. 8 is a cross-sectional view (part 8) showing an example of a joint structure between a laminated current collector and another conductive member. [Figure 26] FIG. 9 is a cross-sectional view showing an example of a joint structure between a laminated current collector and another conductive member. [Figure 27] 10A and 10B are diagrams schematically showing modified examples of the laminated current collector and the metal body. [Figure 28] 28 is a diagram showing a state in which the laminated current collector and the metal body according to the modified example shown in FIG. 27 are bent. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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).

[0028] 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.

[0029] 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.

[0030] 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.

[0031] (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.

[0032] 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.

[0033] 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 .

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 3, an opening 113 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. 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 and a substantially rectangular shape such as a rectangular shape with rounded corners.

[0043] A negative electrode terminal 301 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.

[0044] 4, an opening 114 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. 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.

[0045] A positive electrode terminal 302 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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 .

[0058] 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).

[0059] 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).

[0060] (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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] (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.

[0067] 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.

[0068] The first electrode body 201 includes a negative electrode tab group 220 that is arranged at one end of the first electrode body 201 (FIG. 11) and is electrically connected to the negative electrode 210, and a positive electrode tab group 250 that is arranged at the other end of the first electrode body 201 (FIG. 12) and is electrically connected to the positive electrode 240.

[0069] The second electrode body 202 includes a negative electrode tab group 270 that is arranged at one end of the second electrode body 202 (FIG. 11) and electrically connected to the negative electrode 210, and a positive electrode tab group 280 that is arranged at the other end of the second electrode body 202 (FIG. 12) and electrically connected to the positive electrode 240.

[0070] 11 (negative electrode side structure), the negative electrode tab group 220 and the negative electrode tab group 270 are each electrically connected to a current collector 430 (negative electrode current collector 400A). More specifically, the negative electrode tab group 220 is joined to a current collector 431, and the negative electrode tab group 270 is joined to a current collector 432. The negative electrode tab group 220 and the current collector 431 curve in opposite directions, and the negative electrode tab group 270 and the current collector 432 curve in opposite directions.

[0071] 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 440 (positive electrode current collector 400B). More specifically, the positive electrode tab group 250 is joined to a current collector 441, and the positive electrode tab group 280 is joined to a current collector 442. The positive electrode tab group 250 and the current collector 441 are curved in opposite directions, and the positive electrode tab group 280 and the current collector 442 are curved in opposite directions.

[0072] The lengths of the negative electrode tab groups 220, 270 and the positive electrode tab groups 250, 280 can be changed as appropriate. The lengths of the negative electrode tab groups 220, 270 are preferably the same, but may be different. 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.

[0073] Current collector 431 to which negative electrode tab group 220 is joined is made of a laminate in which multiple metal plates are stacked. Current collector 441 to which positive electrode tab group 250 is joined is made of a laminate in which multiple metal plates are stacked.

[0074] The current collector 432 to which the negative electrode tab group 270 is joined is made of a laminate in which a plurality of metal plates are stacked, and the current collector 442 to which the positive electrode tab group 280 is joined is made of a laminate in which a plurality of metal plates are stacked.

[0075] The current collectors 431, 432 electrically connect the negative electrode terminal 301 to the negative electrode tab group 220 and the negative electrode tab group 270. The current collectors 441, 442 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, 432, 441, 442 (current collectors) are joined to the current collectors 410, 420 (other conductive members) in a state where they are folded at folding portions formed along the Z direction, and are electrically connected to the negative electrode terminal 301 and the positive electrode terminal 302.

[0076] A more stable current collection structure can be configured by dividing each of the current collectors 430, 440 into two current collectors 431, 432 and two current collectors 441, 442. However, the scope of the present technology is not limited to this, and for example, the negative electrode tab groups 220, 270 may be joined to one current collector 430, and the positive electrode tab groups 250, 280 may be joined to one current collector 440. In this way, the joining process can be simplified (reduced in number of times).

[0077] 11 , the current collectors 431 and 432 are joined to the current collector 410 at a portion where the current collectors 431 and 432 overlap each other. In the example of Fig. 12 , the current collectors 441 and 442 are joined to the current collector 420 at a portion where the current collectors 441 and 442 overlap each other. However, the scope of the present technology is not limited thereto, and the current collectors 431, 432, 441, and 442 may be joined to the current collectors 410 and 420 at positions spaced apart from or adjacent to each other on the current collectors 410 and 420.

[0078] The negative electrode tab group 220 and the negative electrode tab group 270 are respectively joined to current collectors 431 and 432. The positive electrode tab group 250 and the positive electrode tab group 280 are respectively joined to current collectors 441 and 442. These joints can be formed by, for example, ultrasonic bonding, resistance welding, laser welding, caulking, or the like.

[0079] 11 , a negative electrode tab group 220 is disposed in the X direction between the end of the current collector 431 on the electrode body 200 side (the right side in the figure) and the end of the current collector 432 on the electrode body 200 side (the right side in the figure) (the gap between the current collectors 431, 432). A negative electrode tab group 270 may be disposed in the gap between the current collectors 431, 432, or both the negative electrode tab groups 220, 270 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.

[0080] 12 , a positive electrode tab group 250 is disposed in the X direction between the end of the current collector 441 on the electrode body 200 side (left side in the figure) and the end of the current collector 442 on the electrode body 200 side (left side in the figure) (the gap between the current collectors 441, 442). A positive electrode tab group 280 may be disposed in the gap between the current collectors 441, 442, or both the positive electrode tab groups 250, 280 may be disposed in the gap between the current collectors 441, 442. This allows the gap between the current collectors 441, 442 to be used effectively.

[0081] 11 and 12 , insulating members 510 and 520 are disposed between the plate-like members 303 and 304 and the sealing plates 120 and 130. An insulating member 530 is disposed between the negative electrode terminal 301 and the sealing plate 120. An insulating member 540 is disposed between the positive electrode terminal 302 and the sealing plate 130. However, the negative electrode terminal 301 and the positive electrode terminal 302 may be electrically connected to the sealing plates 120 and 130, and the sealing plates 120 and 130 may serve as the negative electrode terminal 301 or the positive electrode terminal 302.

[0082] A spacer (not shown) may be disposed between the sealing plates 120, 130 and the main body of the electrode assembly 200 (excluding the negative electrode tab groups 220, 270 and the positive electrode tab groups 250, 280). The spacer may be made of an insulating resin material. The negative electrode tab groups 220, 270 and the positive electrode tab groups 250, 280 are protected by passing through the interior of the spacer.

[0083] Fig. 13 is a diagram showing a modified example of the configuration around the negative electrode current collector 400A. Note that the modified structure shown in Fig. 13 may be adopted not on the negative electrode current collector 400A side but on the positive electrode current collector 400B side.

[0084] 13, the negative electrode tab groups 220, 270 are electrically connected to a current collector 410 (negative electrode current collector 400A). The current collector 410 is electrically connected to the negative electrode terminal 301 via a current collector 450. An insulating member 530 is disposed between the current collector 450 and the sealing plate 120.

[0085] The negative electrode tab group 220 has a curved portion 221. The curved portion 221 is a portion where the negative electrode tab group 220 is curved. The negative electrode tab group 270 has a curved portion 271. The curved portion 271 is a portion where the negative electrode tab group 270 is curved. The negative electrode tab group 220 and the negative electrode tab group 270 are curved in opposite directions so that their tip ends approach each other.

[0086] In the modified example of FIG. 13, 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.

[0087] 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 joints between the negative electrode tab group 220 and the negative electrode tab group 270 and the current collector 410 can be formed by, for example, ultrasonic welding, resistance welding, laser welding, caulking, or the like.

[0088] (Manufacturing process of secondary battery 1) A method for manufacturing the secondary battery according to this embodiment will now be described. Fig. 14 is a flowchart showing the method for manufacturing the secondary battery 1.

[0089] As shown in FIG. 14, the method for manufacturing the secondary battery 1 includes the steps of: (S1) preparing the first electrode body 201; (S2) preparing the second electrode body 202; (S3) electrically connecting the negative electrode 210 to the negative electrode terminal 301 via the current collectors 410, 430; (S4) overlapping the first electrode body 201 and the second electrode body 202; (S5) inserting the first electrode body 201 and the second electrode body 202 into the case body 110; (S6) electrically connecting the positive electrode 240 to the positive electrode terminal 302 via the current collectors 420, 440; (S7) joining the sealing plates 120, 130 to the case body 110 to seal the openings 113, 114; and (S8) conducting a leak test.

[0090] In the steps (S1, S2) 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 tip lengths are the same when bundled. Current collectors 430, 440 are joined to 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.

[0091] The current collector 430 joined to the negative electrode tab group 220 and the negative electrode tab group 270 is assembled to the sealing plate 120. The current collector 410 and the negative electrode terminal 301 are attached to the sealing plate 120 in advance. The current collector 430 is assembled to the sealing plate 120 via the current collector 410. The joint between the current collectors 410 and 430 can be formed by, for example, laser welding. As a result of the above, the current collector 430 is electrically connected to the negative electrode terminal 301 (S3).

[0092] After being electrically connected to the negative electrode terminal 301, the current collectors 431, 432 are bent together with the negative electrode tab groups 220, 270 into the shape shown in Fig. 11. It is preferable that the current collectors 431, 432 are bent simultaneously, but the current collectors 431, 432 may be bent sequentially.

[0093] 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, and the first electrode body 201 and the second electrode body 202 are overlapped (S4).

[0094] 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.

[0095] The first electrode body 201 and the second electrode body 202, which are stacked on top of each other, are inserted into the case body 110 with the current collector 430 side first (S5). When inserting the electrode body 200 into the case body 110, the electrode body 200 may be pulled from the positive electrode side or pushed from the negative electrode side.

[0096] After inserting the electrode assembly 200 into the case body 110, the current collector 440 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 440 is assembled to the sealing plate 130 via the current collector 420. The joint between the current collectors 420 and 440 can be formed by, for example, laser welding. As a result of the above, the current collector 440 is electrically connected to the positive electrode terminal 302 (S6).

[0097] After being electrically connected to the positive electrode terminal 302, the current collectors 441, 442 are bent together with the positive electrode tab groups 250, 280 into the shape shown in Fig. 12. It is preferable that the current collectors 441, 442 are bent simultaneously, but the current collectors 441, 442 may be bent sequentially.

[0098] The sealing plates 120 and 130 are joined to the case body 110 (S7). The sealing plate 120 seals the opening 113 of the case body 110, and the sealing plate 130 seals the opening 114 of the case body 110. This allows the first electrode body 201 and the second electrode body 202 to be housed in the case 100.

[0099] After the above steps are completed, inspections such as a leak test are performed (S8). After the leak test, the secondary battery 1 is dried to remove moisture from inside the case 100. Then, electrolyte is poured into the inside of the case 100 through the liquid filling hole 134. When pouring 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 poured into the inside of the case 100 through the liquid filling hole 134 in the sealing plate 130. Then, degassing charging is performed. The liquid filling hole 134 may be temporarily sealed during degassing charging. The liquid filling hole 134 is then sealed, and the secondary battery 1 is completed.

[0100] In this embodiment, an example has been described in which, after the step (S5) of inserting the first electrode body 201 and the second electrode body 202 into the case 100 body is completed, the current collector 440 is electrically connected (S6) 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 (S6) before the step (S5) of inserting the electrode body 200 into the case body 110 is completely completed (during the insertion step).

[0101] In the present embodiment, an example has been described in which the current collectors 430, 440 are bent after being electrically connected to the negative electrode terminal 301 and the positive electrode terminal 302, but the current collectors 430, 440 may be deformed before being electrically connected to the negative electrode terminal 301 and the positive electrode terminal 302.

[0102] (Joint structure between current collectors 430, 440 and other conductive members) Next, the joining structure between current collectors 430, 440 and other conductive members will be described with reference to Figures 15 to 28. For convenience of illustration and explanation, current collector 431 is mainly shown in Figures 15 to 28, but a similar joining structure can also be applied to current collectors 432, 441, and 442. Furthermore, the joining target of current collector 431 is not limited to current collector 410; for example, current collector 431 may be directly joined to an electrode terminal.

[0103] 15, the current collector 431 is joined to the negative electrode tab group 220 at a joint 431A formed in the first region 10, joined to the current collector 410 at a joint 410A formed in the second region 20, and folded at a third region 30 (folded portion) located between the first region 10 and the second region 20. However, the current collector 431 does not necessarily have to be folded.

[0104] 16, current collector 431 is joined to current collector 410 together with metal member 600. Metal member 600 may be formed of a plate-like member having a different length, width, or thickness from each of the multiple metal plates that make up current collector 431. It is particularly preferable that the thickness of one metal member 600 is greater than the thickness of a single metal plate.

[0105] At joint 431A overlapping with the negative electrode tab group 220, the multiple metal plates constituting the current collector 431 are joined together. Although one joint 431A is illustrated in Fig. 16, the joint 431A may be formed in multiple steps (for example, two steps). Specifically, it is preferable to join the multiple metal plates of the current collector 431 together (forming joint 431A in the current collector 431) and then join the negative electrode tab group 220 to the current collector 431 (forming joint 431A that extends from the current collector 431 to the negative electrode tab group 220).

[0106] The multiple metal plates constituting current collector 431 are bonded together at joint 431B (first bonding region) that overlaps metal member 600 and current collector 410. Joint 431B is formed inside current collector 431 and does not reach metal member 600 or current collector 410. Joints 431A and 431B are preferably formed by ultrasonic bonding or diffusion bonding. In the case of diffusion bonding, the metal plates are preferably bonded together by applying pressure to the stacked metal plates while heating them at a temperature lower than the melting point of the metal plates.

[0107] 16, metal members 600 are arranged on the lower surface (first surface) of current collector 431 facing current collector 410, and on the upper surface (second surface) of current collector 431. Joint portion 410A (second joint region) penetrates joint portion 431B of current collector 431 and the pair of metal members 600, and reaches current collector 410. This joins current collector 431, metal members 600, and current collector 410 to one another.

[0108] Joint 410A can be formed by irradiating a high-energy ray such as a laser beam onto the overlapping portion of current collector 431, metal member 600, and current collector 410. It is preferable to form joint 431B to join multiple metal plates together before forming joint 410A.

[0109] In this way, it is preferable to form joint portions 431A and 431B in current collector 431 before placing current collector 431 on negative electrode tab group 220 and current collector 410. However, the scope of the present technology is not limited to this, and in a state before current collector 431 is joined to negative electrode tab group 220 and current collector 410, the multiple metal plates constituting current collector 431 do not necessarily have to be joined together.

[0110] 16, when viewed from the stacking direction of the multiple metal plates of current collector 431 (the vertical direction in FIG. 16), joint portion 410A and joint portion 431B overlap, and joint portion 410A is included within joint portion 431B. In other words, the area of ​​joint portion 410A is smaller than the area of ​​joint portion 431B.

[0111] The area (S1) of the joint 431B is preferably at least 1.2 times, and more preferably at least 2.5 times, the area (S2) of the joint 410A. S1 is preferably at most 5 times, and more preferably at most 3.5 times, the area (S2) of the joint 410A.

[0112] Note that the areas of the joints 410A and 431B can each vary in the vertical direction in the figure, but the "area of ​​the joint 410A" and the "area of ​​the joint 431B" referred to here refer to the maximum values ​​of the areas that can each vary in the vertical direction in the figure.

[0113] 17 (cross-sectional view), joints 410A and 431B are spaced apart when viewed from the stacking direction (vertical direction in FIG. 17) of the multiple metal plates of current collector 431. More specifically, joint 410A is formed in a region surrounded by joints 431B or a region sandwiched between multiple joints 431B.

[0114] 16, by forming joint 410A in the area enclosed by joint 431B, it is possible to eliminate or minimize gaps between the metal plates before the laser welding process for forming joint 410A, thereby improving the quality of the laser welding.

[0115] 17, by forming the joint 431A in advance around the joint 410A, the stress caused by solidification shrinkage that occurs during laser welding to form the joint 410A can be absorbed by the joint 431A, which can improve the quality of the laser welding.

[0116] However, the scope of the present technology is not limited to an example in which joint 410A is completely contained within joint 431B (FIG. 16) or an example in which joint 410A and joint 431B are completely separated (FIG. 17), and may also include an example in which a portion of joint 410A overlaps a portion of joint 431B.

[0117] In the example shown in Figures 18 and 19 (cross-sectional views), before the current collector 431 and the metal member 600 are joined to the current collector 410, i.e., before the joint 410A is formed, the current collector 431 and the metal member 600 are joined by the joint 431B.

[0118] 20 (cross-sectional view), 21 (plan view), and 22 (cross-sectional view), metal member 600 is disposed beyond the longitudinal end of current collector 431. Metal member 600 shown in Fig. 20 to Fig. 22 can be formed, for example, by bending a plate-shaped member.

[0119] In the example shown in FIG. 23 (plan view), metal member 600 is disposed beyond the end of current collector 431 in the width direction.

[0120] In the example shown in Figure 24 (cross-sectional view), metal member 600 is arranged only on the upper surface of current collector 431, and in the example shown in Figure 25 (cross-sectional view), metal member 600 is arranged only on the lower surface of current collector 431.

[0121] In the example shown in FIG. 26 (cross-sectional view), a metal member 600 is disposed between a current collector 431 connected to the negative electrode tab group 220 (first tab group) and a current collector 432 connected to the positive electrode tab group 250 (second tab group), and the two current collectors 431, 432 are joined to the current collector 410 at a joint 410A together with the metal member 600 while overlapping each other.

[0122] 26, by joining two current collectors 431, 432 together with a metal member 600 to the current collector 410 in a stacked state, it is not necessary to provide one metal member 600 for each of the current collectors 431, 432, and space can be saved in the current collecting structure. As a result, the energy density of the secondary battery 1 can be improved. Note that three or more current collectors may be joined together with one metal member 600 to the current collector 410 in a stacked state. Alternatively, three or more current collectors may be joined together with two or more metal members 600 to the current collector 410 in a stacked state.

[0123] As shown in FIGS. 24 to 26 , the thickness (T2) of one of the multiple metal plates constituting the current collectors 431, 432 is preferably greater than the thickness (T1) of one of the negative electrode tabs 230 and positive electrode tabs 260 constituting the negative electrode tab group 220 and positive electrode tab group 250. More preferably, the thickness (T2) of one of the multiple metal plates constituting the current collectors 431, 432 is approximately 5 times or more, and even more preferably, approximately 8 times or more, the thickness (T1) of one of the negative electrode tabs 230 and positive electrode tabs 260 constituting the negative electrode tab group 220 and positive electrode tab group 250. More preferably, T2 is approximately 20 times or less, and even more preferably, approximately 12 times or less, of T1. The thickness (T2) of the metal plate is preferably, for example, approximately 0.05 mm or more, and more preferably, approximately 0.08 mm or more. Also, it is preferably about 0.5 mm or less, more preferably about 0.3 mm or less, and even more preferably about 0.2 mm or less.

[0124] The thickness (T3) of the metal member 600 is preferably larger than the thickness (T1) of each of the negative electrode tabs 230 and positive electrode tabs 260 constituting the negative electrode tab group 220 and the positive electrode tab group 250. The thickness (T3) of the metal member 600 is also preferably larger than the thickness (T2) of each of the multiple metal plates constituting the current collectors 431 and 432. More preferably, the thickness (T3) of the metal member 600 is approximately 1.5 times or more the thickness (T2) of each of the multiple metal plates constituting the current collectors 431 and 432. More preferably, T3 is approximately 5 times or less, and even more preferably, approximately 3 times or less, of T2. The thickness (T4) of the current collector 410 is preferably larger than the thickness (T3) of the metal member 600.

[0125] The metal member 600 is preferably made of the same material as the current collectors 410, 420, 430, and 440. For example, on the negative electrode side, the metal member 600 can be made of copper or a copper alloy, and on the positive electrode side, the metal member 600 can be made of aluminum or an aluminum alloy. However, the material of the metal member 600 may be different from that of the current collectors 410, 420, 430, and 440; for example, the metal member 600 on the negative electrode side can be made of nickel. The metal member 600 made of nickel has a high laser light absorption rate and is therefore easily melted during laser welding.

[0126] When metal member 600 is placed on the upper surface of current collector 431, the final stage of solidification and shrinkage occurs inside metal member 600 when joint 410A is formed. Therefore, even if a recess occurs in metal member 600 due to solidification and shrinkage, the conduction area of ​​current collector 431 is prevented from being impaired.

[0127] When metal member 600 is placed between current collector 431 and current collector 410, it buffers the difference in the rate of solidification and shrinkage between current collector 431 and current collector 410, and can prevent a gap from occurring at the joint between current collector 431 and current collector 410.

[0128] In the secondary battery 1 according to the present embodiment, by using current collectors 430, 440 made of a laminate of multiple metal plates, it is possible to provide current collectors 430, 440 that are easy to deform stably while suppressing an increase in resistance. As a result, it is possible to reduce the size of negative electrode current collector 400A and positive electrode current collector 400B, and improve the energy density of secondary battery 1.

[0129] Furthermore, in the secondary battery 1 according to this embodiment, by providing a metal member 600 that is joined to the current collectors 410, 420 (other conductive members) together with the current collectors 430, 440, it is possible to stably ensure electrical conduction when joining the current collectors 430, 440 to the current collectors 410, 420, thereby improving the reliability of the secondary battery 1.

[0130] Furthermore, by joining the metal plates of current collectors 431, 432 together before forming joint 410A by welding with irradiation of high-energy rays such as laser light, it is possible to prevent holes or voids from forming between the metal plates during welding with irradiation of high-energy rays, thereby improving the reliability of joint 410A and further improving the reliability of secondary battery 1.

[0131] Furthermore, by joining the negative electrode tab group 220 and the positive electrode tab group 250 to the current collectors 430, 440 before electrically connecting the negative electrode tab group 220 and the positive electrode tab group 250 to the current collectors 410, 420, the negative electrode tabs 230 and the positive electrode tabs 260, which have a relatively small thickness (T1), can be effectively protected and unintended deformation or damage can be suppressed, thereby further improving the reliability of the secondary battery 1.

[0132] Next, modified examples of the current collector 431 and the metal member 600 will be described with reference to FIGS. 27 and 28. As shown in FIG. 27, in this modified example, the metal member 600 is provided so as to cover the outer surface of the current collector 431. The metal member 600 is provided so as to extend from above the joint 410A with the current collector 410 toward the negative electrode tab group 220. As shown in FIG. 28, the metal member 600 is folded together with the current collector 431 between the joint 410A and the joint 431A. Here, for example, the length of the metal member 600 can be set to be approximately 1.2 times or more, preferably approximately 1.5 times or more, and more preferably approximately 2 times or more the length of the longest metal plate among the metal plates constituting the current collector 431.

[0133] However, the metal member 600 does not necessarily have to reach above the negative electrode tab group 220. Moreover, the metal member 600 does not necessarily have to reach the vicinity of the negative electrode tab group 220. The metal member 600 may terminate midway in the bent portion.

[0134] 27 and 28, the number of metal plates constituting the current collector 431 may be different between the current collector 410 side and the negative electrode tab group 220 side. More specifically, it is preferable to make the number of metal plates (M1) on the current collector 410 side greater than the number of metal plates (M2) on the negative electrode tab group 220 side. By increasing the number of metal plates on the current collector 410 side (for example, M1 = 8 plates, M2 = 4 plates), even if the conduction path is interrupted in some metal plates of the current collector 431 when forming the joint 410A, it is possible to ensure a predetermined conduction area for the current collector 431 as a whole.

[0135] 27 and 28, by providing metal member 600 so as to cover the outer surface of current collector 431, even if fragments are generated from a metal plate of current collector 431 during the formation of joint 410A, the fragments can be prevented from moving within case 100 of secondary battery 1. Furthermore, by sandwiching current collector 431 between metal members 600, the shape of current collector 431 can be stabilized. As a result of the above, the reliability of secondary battery 1 can be improved.

[0136] (supplement) In this embodiment, as shown in Figures 11 and 12, when the first electrode body 201 and the second electrode body 202 are overlapped, the current collectors 431 and 432 are curved in the same direction and the current collectors 441 and 442 are bent so as to be curved in the same direction, but the current collectors 431 and 432 may be curved in opposite directions and the current collectors 441 and 442 may be bent so as to be curved in opposite directions.

[0137] In the present embodiment, an example has been described in which, in the state shown in FIG. 11 , the current collectors 431, 432 are joined to the negative electrode tab groups 220, 270 from the same side (both are on the right side in the figure relative to the negative electrode tab groups 220, 270), and, in the state shown in FIG. 12 , the current collectors 431, 432 are joined to the positive electrode tab groups 250, 280 from the same side (both are on the left side in the figure relative to the positive electrode tab groups 250, 280).

[0138] However, the scope of the present technology is not limited to the above, and in the state shown in FIG. 11, the current collectors 431, 432 may be joined to the negative electrode tab groups 220, 270 from different sides, and in the state shown in FIG. 12, the current collectors 441, 442 may be joined to the positive electrode tab groups 250, 280 from different sides.

[0139] 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.

[0140] 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]

[0141] 1 secondary battery, 10 first region, 20 second region, 30 third region, 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 inlet, 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, 270 negative electrode tab group, 221, 271 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, 280 positive electrode tab group, 260 Positive electrode tab, 300 electrode terminal, 301 negative electrode terminal, 302 positive electrode terminal, 303, 304 plate-shaped member, 400, 410, 420, 430, 431, 432, 440, 441, 442, 450 current collector, 400A negative electrode current collector, 400B positive electrode current collector, 410A, 431A, 431B, 432A, 432B joint, 510, 520, 530, 540 insulating member.

Claims

1. an electrode body including a first electrode, a second electrode having a polarity different from that of the first electrode, and an electrode tab electrically connected to the first electrode; a case for accommodating the electrode assembly; a current collector electrically connected to the electrode tab, the current collector being a laminate of a plurality of metal plates; Another conductive member connected to the current collector; A secondary battery comprising: a metal member having a length, width, or thickness different from each of the plurality of metal plates in the current collector, and joined to the other conductive member together with the current collector.

2. the current collector includes a first region, a second region, and a folded portion; the electrode tab is bonded to the first region; the other conductive member is joined to the second region; The secondary battery according to claim 1 , wherein the bent portion is disposed between the first region and the second region.

3. the current collector has a first surface facing the other conductive member and a second surface located opposite to the first surface, The secondary battery according to claim 1 , wherein the metal members are disposed on the first surface and the second surface.

4. 3. The secondary battery according to claim 1, wherein the current collector includes at least a first bonding region where the plurality of metal plates are bonded together and do not reach the other conductive member, and a second bonding region where the current collector, the metal member, and the other conductive member are bonded to one another.

5. The secondary battery according to claim 4 , wherein an area of ​​the second joint region is smaller than an area of ​​the first joint region when viewed from the stacking direction of the plurality of metal plates.

6. The secondary battery according to claim 4 , wherein the first bonding region and the second bonding region overlap when viewed from the stacking direction of the plurality of metal plates.

7. The secondary battery according to claim 4 , wherein the first bonding region and the second bonding region are spaced apart when viewed from the stacking direction of the plurality of metal plates.

8. a thickness of one of the plurality of metal plates is greater than a thickness of one of the electrode tabs; 3. The secondary battery according to claim 1, wherein the thickness of the metal member is greater than the thickness of one of the plurality of metal plates.

9. a first tab group and a second tab group each including a plurality of the electrode tabs are provided; two current collectors are provided, one of the current collectors is connected to the first tab group, and the other current collector is connected to the second tab group; 3. The secondary battery according to claim 1, wherein two of the current collectors are stacked and joined together with the metal member to the other conductive member.

10. an electrode body including a first electrode, a second electrode having a polarity different from that of the first electrode, and an electrode tab electrically connected to the first electrode; a case for accommodating the electrode assembly; a current collector formed of a laminate of a plurality of metal plates; Another conductive member connected to the current collector; a metal member having a length, width, or thickness different from each of the plurality of metal plates in the current collector, and joined to the other conductive member together with the current collector, joining the electrode tab to the current collector; and joining the current collector and the metal member to the other conductive member by irradiating a portion where the current collector and the metal member are overlapped with high-energy rays.

11. The method for manufacturing a secondary battery according to claim 10 , further comprising the step of bending the current collector after joining the current collector and the metal member to the other conductive member.

12. further comprising a step of joining the plurality of metal plates of the current collector to each other, The method for manufacturing a secondary battery according to claim 10 or 11, wherein the electrode tab is joined to the current collector after the plurality of metal plates are joined to each other.

13. the current collector has a first surface facing the other conductive member and a second surface located opposite to the first surface, 12. The method for manufacturing a secondary battery according to claim 10, wherein the metal member is disposed on at least one of the first surface and the second surface, and a high-energy ray is irradiated to a portion where the metal member is disposed, thereby joining the current collector and the metal member to the other conductive member.

14. further comprising a step of joining the plurality of metal plates of the current collector to each other, 12. The method for manufacturing a secondary battery according to claim 10 or 11, wherein, after the plurality of metal plates are joined to each other, high-energy rays are irradiated onto an area where the plurality of metal plates are not joined to each other, thereby joining the current collector and the metal member to the other conductive member.

15. further comprising a step of joining the plurality of metal plates of the current collector to each other, 12. The method for manufacturing a secondary battery according to claim 10 or 11, wherein after the plurality of metal plates are joined to each other, a region where the plurality of metal plates are joined to each other is irradiated with high-energy rays, thereby joining the current collector and the metal member to the other conductive member.

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