Secondary battery and method for manufacturing the same

Abstract

To provide a secondary battery having high energy density and high reliability, and a method for manufacturing the secondary battery.SOLUTION: In the secondary battery, a first electrode assembly and a second electrode assembly are stacked. A first electrode tab and a third electrode tab connected to a first electrode in the first electrode assembly and the second electrode assembly are joined to a first current collector. The first current collector is formed of a first laminated body in which a plurality of metal plates are laminated. A second electrode of each of the first electrode assembly and the second electrode assembly has a polarity different from that of the first electrode. A second electrode tab and a fourth electrode tab connected to the second electrode are joined to a second current collector.SELECTED DRAWING: Figure 12

Description

[Technical Field]

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

[0002] Japanese Patent No. 4537353 (Patent Document 1) discloses a prismatic battery in which a positive electrode terminal is provided on one side of the battery case and a negative electrode terminal is provided on the other end.

[0003] Japanese Patent Application Laid-Open Publication No. 2021-099936 (Patent Document 2) discloses a battery in which a group of tabs connected to a current collector are bent. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 4537353 [Patent Document 2] Patent Publication No. 2021-099936 Summary of the Invention [Problem to be solved by the invention]

[0005] There is a demand for increasing the energy density of secondary batteries. There is also a demand for improving the reliability of secondary batteries. From these perspectives, there is still room for improvement in conventional secondary batteries.

[0006] An object of the present technology is to provide a secondary battery having high energy density and high reliability, and a method for manufacturing the same. [Means for solving the problem]

[0007] The present technology provides the following secondary battery and method for manufacturing the same.

[0008] [1] A secondary battery comprising: a first electrode body and a second electrode body, each including a first electrode and a second electrode having a polarity opposite to that of the first electrode; a case accommodating the first electrode body and the second electrode body; and a first electrode terminal electrically connected to the first electrode, wherein the first electrode body includes a first electrode tab disposed at one end of the first electrode body and electrically connected to the first electrode, and a second electrode tab disposed at the other end of the first electrode body and electrically connected to the second electrode, and the second electrode body includes a third electrode tab disposed at one end of the second electrode body and electrically connected to the first electrode, and a fourth electrode tab disposed at the other end of the second electrode body and electrically connected to the second electrode, and the battery is made of a first laminate in which a plurality of metal plates are stacked, and further comprising: a first current collector to which the first electrode tab is joined; and a second current collector to which the second electrode tab and the fourth electrode tab are joined. a step of joining the first electrode tab to the first current collector after the first electrode body and the second electrode body are fabricated; a step of electrically connecting the second electrode tab and the fourth electrode tab to the second current collector in a state in which the first electrode body is disposed on one side of the second current collector and the second electrode body is disposed on the other side of the second current collector after the first electrode body and the second electrode body are fabricated; a step of folding the second electrode tab and the fourth electrode tab to overlap the first electrode body and the second electrode body after the second electrode tab and the fourth electrode tab are electrically connected to the second current collector; and a step of electrically connecting the first current collector joined to the first electrode tab to the first electrode terminal after the first electrode body and the second electrode body are overlapped.

[0009] [2] The method for manufacturing a secondary battery described in [1], wherein the secondary battery is made of a second laminate in which a plurality of metal plates are stacked, and further includes a third current collector to which the third electrode tab is joined, and further includes a step of electrically connecting the third current collector joined to the third electrode tab to the first electrode terminal after overlapping the first electrode body and the second electrode body.

[0010] [3] The method for manufacturing a secondary battery according to [1], further comprising the step of joining the third electrode tab to the first current collector after the first electrode body and the second electrode body are stacked together.

[0011] [4] The method for manufacturing a secondary battery according to any one of [1] to [3], further comprising a step of bending the first current collector after electrically connecting the first current collector joined to the first electrode tab to the first electrode terminal.

[0012] [5] The method for manufacturing a secondary battery according to any one of [1] to [4], wherein the secondary battery further comprises a second electrode terminal electrically connected to the second electrode, and the case includes a case main body including a first opening located at one end of the case and a second opening located at the other end of the case, a first sealing plate that seals the first opening, and a second sealing plate that seals the second opening, the first electrode terminal being provided on the first sealing plate and the second electrode terminal being provided on the second sealing plate, the method comprising the steps of: electrically connecting the second current collector joined to the second electrode tab and the fourth electrode tab to the second electrode terminal; and inserting the first electrode body and the second electrode body into the case main body, with the first current collector side leading, after electrically connecting the second current collector to the second electrode terminal.

[0013] [6] The method for manufacturing a secondary battery described in [5], wherein the step of electrically connecting the first current collector to the first electrode terminal is performed after the first electrode body and the second electrode body are inserted into the case body, with the first electrode body and the second electrode body disposed within the case body.

[0014] [7] The method for manufacturing a secondary battery according to any one of [1] to [6], wherein the first current collector includes a first region where the plurality of metal plates are joined to one another and a second region where the plurality of metal plates are not joined to one another, and the first current collector is bent in the second region.

[0015] [8] The method for manufacturing a secondary battery according to any one of [2] and [4] to [7], wherein the first current collector and the third current collector are curved in the same direction when the first electrode body and the second electrode body are stacked together.

[0016] [9] A method for manufacturing a secondary battery according to any one of [1] to [8], wherein a first electrode tab group is provided in which a plurality of the first electrode tabs are stacked, and the total thickness of the first current collector is greater than the total thickness of the first electrode tab group.

[0017]

[10] A device comprising: a first electrode body and a second electrode body, each including a first electrode and a second electrode having a polarity different from that of the first electrode; a case for accommodating the first electrode body and the second electrode body; and a first electrode terminal electrically connected to the first electrode, wherein the first electrode body is disposed at one end of the first electrode body and includes a first electrode tab electrically connected to the first electrode, and a second electrode tab is disposed at the other end of the first electrode body and electrically connected to the second electrode; and the second electrode body is disposed at one end of the second electrode body and includes a first electrode tab electrically connected to the first electrode. a third electrode tab electrically connected to the second electrode, and a fourth electrode tab arranged at the other end of the second electrode body and electrically connected to the second electrode, the secondary battery being made of a first laminate in which a plurality of metal plates are stacked, the secondary battery further comprising a first current collector to which the first electrode tab is joined, and a second current collector to which the second electrode tab and the fourth electrode tab are joined, the first current collector and the second current collector being arranged to overlap, the second electrode tab and the fourth electrode tab being curved in directions such that their respective tips approach each other, and the first current collector being bent. [Effects of the Invention]

[0018] According to the present technology, it is possible to provide a secondary battery with high energy density and a method for manufacturing the same. [Brief explanation of the drawings]

[0019] [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. DETAILED DESCRIPTION OF THE INVENTION

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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).

[0024] 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.

[0025] 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.

[0026] 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.

[0027] (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.

[0028] 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.

[0029] 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 .

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 3, an opening 113 (second 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 (second 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.

[0039] A negative electrode terminal 301 (second 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.

[0040] 4, an opening 114 (first 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 (first 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.

[0041] A positive electrode terminal 302 (first 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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 .

[0054] 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).

[0055] 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).

[0056] (Configuration of electrode body 200) 8, the negative electrode 210 (second 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.

[0057] 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.

[0058] As shown in Fig. 10, the positive electrode 240 (first 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] (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.

[0063] 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.

[0064] The first electrode body 201 includes a positive electrode tab group 250 (first electrode tabs) that are arranged at one end of the first electrode body 201 (FIG. 12) and are electrically connected to the positive electrode 240, and a negative electrode tab group 220 (second electrode tabs) that are arranged at the other end of the first electrode body 201 (FIG. 11) and are electrically connected to the negative electrode 210.

[0065] The second electrode body 202 includes a positive electrode tab group 280 (third electrode tabs) that are arranged at one end of the second electrode body 202 (FIG. 12) and are electrically connected to the positive electrode 240, and a negative electrode tab group 270 (fourth electrode tabs) that are arranged at the other end of the second electrode body 202 (FIG. 11) and are electrically connected to the negative electrode 210.

[0066] 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 (second 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.

[0067] 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.

[0068] Negative electrode tab group 220 and negative electrode tab group 270 are curved in opposite directions so that their leading ends approach each other.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] The current collector 431 (first current collector) to which the positive electrode tab group 250 is joined is made of a laminate (first laminate) in which a plurality of metal plates 4300 (see FIG. 20) described below are stacked. Similarly, the current collector 432 (third current collector) to which the positive electrode tab group 280 is joined is made of a laminate (second laminate) in which a plurality of metal plates 4300 (see FIG. 20) are stacked. In the current collectors 431 and 432, the number of stacked metal plates 4300 is two or more, preferably three or more, and more preferably five or more. Also, for example, the number can be 20 or less, preferably 15 or less, and more preferably 10 or less. Note that the same can be applied when a current collector in which metal plates are stacked is used on the negative electrode side.

[0077] 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.

[0078] 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).

[0079] 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.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] 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.

[0084] 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.

[0085] (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.

[0086] 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.

[0087] 14 to 19 are diagrams showing the steps in the method for manufacturing the secondary battery 1. FIG.

[0088] 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.

[0089] 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).

[0090] 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.

[0091] 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.

[0092] 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.

[0093] 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.

[0094] 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 and a negative electrode terminal 301 have been 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. As a result of the above, the current collector 410 is electrically connected to the negative electrode terminal 301 (S5).

[0095] 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.

[0096] 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.

[0097] 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.

[0098] 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).

[0099] 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.

[0100] 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).

[0101] 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.

[0102] 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.

[0103] 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.

[0104] 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.

[0105] 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).

[0106] 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.

[0107] (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.

[0108] 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 (first portion). 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 current collector 420) are bonded to the first region 430A and the second region 430B.

[0109] It is preferable that the connection portion 430C (second portion) 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 regions other than the connection portion 430C (the first region 430A and the second region 430B) where the multiple metal plates 4300 are not joined to one another.

[0110] 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.

[0111] 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.

[0112] Metal plate 4300 can be made of, for example, aluminum or an aluminum alloy. Metal plate 4300 can also be made of copper, a copper alloy, nickel, a nickel alloy, iron, or an iron alloy.

[0113] 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. The thickness of one metal plate 4300 is preferably, for example, about 0.05 mm or more, and more preferably about 0.08 mm or more. Furthermore, the thickness of one metal plate 4300 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.

[0114] The thickness of one metal plate 4300 is preferably about 1 / 2 or less, and more preferably about 1 / 5 or less, of the thickness of current collector 420 on the positive electrode side.

[0115] The same can be applied when a current collector having a metal plate laminated thereon is used on the negative electrode side.

[0116] The number of metal plates 4300 constituting the current collectors 431, 432 can be changed as appropriate. The total thickness (first thickness: T1) of the current collectors 431, 432 is preferably greater than the total thickness (second thickness: T2) of the positive electrode tab groups 250, 280 joined to the current collectors 431, 432. More preferably, T1 / T2 is approximately 1.5 or greater, and even more preferably, T1 / T2 is approximately 2 or greater.

[0117] The "total thickness of the current collectors 431, 432" refers to the total thickness of the portions of the current collectors 431, 432 where there are no irregularities. The "total thickness of the positive electrode tab groups 250, 280" refers to the total thickness of the portions where the positive electrode tab groups 250, 280 are gathered together, excluding the joint portions 431A, 432A.

[0118] 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 is easy to deform stably 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.

[0119] In a state in which the first electrode body 201 and the second electrode body 202 are disposed in the case body 110, the current collector 430 connected to the positive electrode tab groups 250, 280 is electrically connected to the positive electrode terminal 302, and then the current collector 430 is folded, a secondary battery 1 with high energy density and high reliability can be manufactured more stably and efficiently by configuring the current collector 430 as a laminate of multiple metal plates 4300. In this case, it is particularly preferable that the negative electrode tab groups 220, 270 are configured so that they are each joined to one surface of the current collector 410 in a curved state, as shown in FIG. 11 . Note that the positive and negative electrode sides may be configured in reverse.

[0120] 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.

[0121] 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.

[0122] 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.

[0123] (supplement) In this embodiment, as shown in FIG. 12, when the first electrode body 201 and the second electrode body 202 are stacked together, the current collectors 431 and 432 are bent so as to curve in the same direction, but the current collectors 431 and 432 may also be bent so as to curve in opposite directions.

[0124] In the present embodiment, an example has been described in which 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 with respect to the positive electrode tab groups 250, 280) in the state shown in Fig. 12. In this case, in the state before the first electrode body 201 and the second electrode body 202 are superimposed (Figs. 14 and 15), the current collectors 431, 432 are joined to the positive electrode tab groups 250, 280 from different sides.

[0125] However, the scope of the present technology is not limited to the above, and the current collectors 431, 432 may be joined to the positive electrode tab groups 250, 280 from different sides in the state shown in Fig. 12. In this case, in the state before the first electrode body 201 and the second electrode body 202 are superimposed (Figs. 14 and 15), the current collectors 431, 432 are joined to the positive electrode tab groups 250, 280 from the same side.

[0126] 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), but the scope of the present technology is not limited to this, and the positive electrode side and the negative electrode side may have opposite structures to the above. Also, instead of a single member, a current collector 410 made of an integrated plurality of members may be used.

[0127] 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 one electrode tab is joined to a current collector may also be used.

[0128] 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]

[0129] 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 current collector, 400B positive electrode current collector, 410A, 420A, 431A, 432A, 440A joint portion, 430A first region, 430B second region, 430C connection portion, 430D hole portion, 510, 520, 530, 540 insulating member, 4300 metal plate.

Claims

1. a first electrode body and a second electrode body each including a first electrode and a second electrode having a polarity different from that of the first electrode; a case that houses the first electrode body and the second electrode body; a first electrode terminal electrically connected to the first electrode, the first electrode body includes a first electrode tab disposed at one end of the first electrode body and electrically connected to the first electrode, and a second electrode tab disposed at the other end of the first electrode body and electrically connected to the second electrode, the second electrode body includes a third electrode tab disposed at one end of the second electrode body and electrically connected to the first electrode, and a fourth electrode tab disposed at the other end of the second electrode body and electrically connected to the second electrode, a first current collector including a first laminate in which a plurality of metal plates are stacked, to which the first electrode tab is joined; a second current collector to which the second electrode tab and the fourth electrode tab are joined, fabricating the first electrode body and the second electrode body; a step of joining the first electrode tab to the first current collector after fabricating the first electrode body and the second electrode body; a step of electrically connecting the second electrode tab and the fourth electrode tab to the second current collector in a state in which the first electrode body is disposed on one side of the second current collector and the second electrode body is disposed on the other side of the second current collector after the first electrode body and the second electrode body are fabricated; a step of folding the second electrode tab and the fourth electrode tab after electrically connecting the second electrode tab and the fourth electrode tab to the second current collector, and overlapping the first electrode body and the second electrode body; and after the first electrode body and the second electrode body are stacked together, electrically connecting the first current collector joined to the first electrode tab to the first electrode terminal.

2. the secondary battery further includes a third current collector formed of a second stack of a plurality of metal plates and to which the third electrode tab is joined; 2. The method for manufacturing a secondary battery according to claim 1, further comprising the step of electrically connecting the third current collector joined to the third electrode tab to the first electrode terminal after the first electrode body and the second electrode body are overlapped.

3. The method for manufacturing a secondary battery according to claim 1 , further comprising the step of joining the third electrode tab to the first current collector after the first electrode body and the second electrode body are stacked together.

4. 4. The method for manufacturing a secondary battery according to claim 1, further comprising the step of bending the first current collector after electrically connecting the first current collector joined to the first electrode tab to the first electrode terminal.

5. the secondary battery further includes a second electrode terminal electrically connected to the second electrode; the case includes a case body including a first opening located at one end of the case and a second opening located at the other end of the case, a first sealing plate that seals the first opening, and a second sealing plate that seals the second opening; the first electrode terminal is provided on the first sealing plate, the second electrode terminal is provided on the second sealing plate, electrically connecting the second current collector joined to the second electrode tab and the fourth electrode tab to the second electrode terminal; 4. The method for manufacturing a secondary battery according to claim 1, further comprising the steps of: electrically connecting the second current collector to the second electrode terminal; and then inserting the first electrode body and the second electrode body into the case body, starting with the first current collector.

6. 6. The method for manufacturing a secondary battery according to claim 5, wherein the step of electrically connecting the first current collector to the first electrode terminal is performed after the first electrode body and the second electrode body are inserted into the case body, with the first electrode body and the second electrode body being disposed within the case body.

7. the first current collector includes a first region where the plurality of metal plates are joined to one another and a second region where the plurality of metal plates are not joined to one another, The method for manufacturing a secondary battery according to claim 1 , wherein the first current collector is bent in the second region.

8. The method for manufacturing a secondary battery according to claim 2 , wherein the first current collector and the third current collector are curved in the same direction with the first electrode body and the second electrode body overlapped.

9. a first electrode tab group is provided in which a plurality of the first electrode tabs are stacked; The method for manufacturing a secondary battery according to claim 1 , wherein a total thickness of the first current collector is greater than a total thickness of the first electrode tab group.

10. a first electrode body and a second electrode body each including a first electrode and a second electrode having a polarity different from that of the first electrode; a case that houses the first electrode body and the second electrode body; a first electrode terminal electrically connected to the first electrode, the first electrode body includes a first electrode tab disposed at one end of the first electrode body and electrically connected to the first electrode, and a second electrode tab disposed at the other end of the first electrode body and electrically connected to the second electrode, the second electrode body includes a third electrode tab disposed at one end of the second electrode body and electrically connected to the first electrode, and a fourth electrode tab disposed at the other end of the second electrode body and electrically connected to the second electrode, a first current collector including a first laminate in which a plurality of metal plates are stacked, to which the first electrode tab is joined; a second current collector to which the second electrode tab and the fourth electrode tab are joined, the first current collector and the second current collector are arranged to overlap each other, the second electrode tab and the fourth electrode tab are curved such that their respective tip portions approach each other, The secondary battery, wherein the first current collector is folded.

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