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: The secondary battery includes a first current collector to which a first electrode tab is joined and a second current collector to which a second electrode tab is joined, the first current collector being formed of a first laminated body in which a plurality of metal plates are laminated and having a first bent portion, and the second current collector being formed of a second laminated body in which a plurality of metal plates are laminated and having a second bent portion.SELECTED DRAWING: Figure 14

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 including a first electrode and a second electrode having a polarity opposite to that of the first electrode; and a case that houses the first electrode body, wherein the first electrode body includes a first electrode tab that is arranged at one end of the first electrode body and electrically connected to the first electrode, and a second electrode tab that is arranged at the other end of the first electrode body and electrically connected to the second electrode; a first current collector to which the first electrode tab is joined; and a second current collector to which the second electrode tab is joined; wherein the first current collector is made of a first laminate in which a plurality of metal plates are stacked and has a first bent portion; and the second current collector is made of a second laminate in which a plurality of metal plates are stacked and has a second bent portion.

[0009] [2] The secondary battery according to [1], further comprising a second electrode body including the first electrode and the second electrode and housed in the case, wherein the second electrode body includes a third electrode tab arranged at one end of the second electrode body and electrically connected to the first electrode, and a fourth electrode tab arranged at the other end of the second electrode body and electrically connected to the second electrode, and further comprising a third current collector to which the third electrode tab is joined and a fourth current collector to which the fourth electrode tab is joined, wherein the third current collector is made of a third laminate in which a plurality of metal plates are stacked and has a third bent portion, and the fourth current collector is made of a fourth laminate in which a plurality of metal plates are stacked and has a fourth bent portion.

[0010] [3] The secondary battery described in [2], wherein the first electrode body and the second electrode body are arranged in the case in a stacked state, the first current collector and the third current collector are connected to a first conductive member, and the second current collector and the fourth current collector are connected to a second conductive member.

[0011] [4] The secondary battery according to [2] or [3], wherein the first current collector and the third current collector are curved in the same direction as each other, and the second current collector and the fourth current collector are curved in the same direction as each other.

[0012] [5] The secondary battery according to any one of [2] to [4], wherein the first bent portion, the second bent portion, the third bent portion, and the fourth bent portion are formed along a first direction, and when viewed from the first direction, a portion of the first current collector to which the first electrode tab is joined and a portion of the third current collector to which the third electrode tab is joined are formed at positions spaced apart from each other, and when viewed from the first direction, a portion of the second current collector to which the second electrode tab is joined and a portion of the fourth current collector to which the fourth electrode tab is joined are formed at positions spaced apart from each other.

[0013] [6] The secondary battery according to any one of [1] to [5], wherein the first electrode is a negative electrode, the second electrode is a positive electrode, each of the plurality of metal plates constituting the first current collector has a first plate thickness, each of the plurality of metal plates constituting the second current collector has a second plate thickness, and the first plate thickness is equal to or less than (the same as or less than) the second plate thickness.

[0014] [7] The secondary battery according to any one of [1] to [6], wherein the first electrode is a negative electrode, the second electrode is a positive electrode, the first current collector has a first lamination thickness, the second current collector has a second lamination thickness, and the first lamination thickness is less than or equal to (the same as, or less than) the second lamination thickness.

[0015] [8] The secondary battery according to any one of [1] to [7], wherein the first electrode is a negative electrode, the second electrode is a positive electrode, the first current collector has a first portion with a locally small conductive area, the second current collector has a second portion with a locally small conductive area, and the conductive area of ​​the second portion is less than or equal to (the same as or less than) the conductive area of ​​the first portion.

[0016] [9] The secondary battery according to any one of [1] to [8], wherein the first electrode is a negative electrode, the second electrode is a positive electrode, and the minimum curvature of the second bend portion is less than (the same as, or less than) the minimum curvature of the second bend portion.

[0017]

[10] A method for manufacturing a secondary battery comprising: a first electrode assembly including a first electrode and a second electrode having a polarity opposite to that of the first electrode; and a case accommodating the first electrode assembly, wherein the first electrode assembly includes a first electrode tab disposed at one end of the first electrode assembly and electrically connected to the first electrode, and a second electrode tab disposed at the other end of the first electrode assembly and electrically connected to the second electrode; the secondary battery further comprising: a first current collector formed of a first laminate in which a plurality of metal plates are stacked and to which the first electrode tab is joined; a second current collector formed of a second laminate in which a plurality of metal plates are stacked and to which the second electrode tab is joined; a first conductive member joined to the first current collector; and a second conductive member joined to the second current collector. a step of joining the first electrode tab to the first current collector; a step of connecting the first current collector connected to the first electrode tab to the first conductive member; a step of bending the first current collector between a portion of the first current collector joined to the first electrode tab and a portion of the first current collector joined to the first conductive member; a step of joining the second electrode tab to the second current collector; a step of connecting the second current collector connected to the second electrode tab to the second conductive member; and a step of bending the second current collector between the portion of the second current collector joined to the second electrode tab and a portion of the second current collector joined to the second conductive member. [Effects of the Invention]

[0018] According to the present technology, it is possible to provide a secondary battery having high energy density and high reliability, 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. [Figure 21] 10A and 10B are diagrams for explaining the dimensional relationship around the joint between the electrode tab and the current collector. [Figure 22] FIG. 10 is a diagram for explaining the bending angle of the 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 (first opening) is provided at the end of case body 110 on the -X side in the X direction. Opening 113 is sealed with sealing plate 120 (first sealing plate). A joint 115 is formed in opening 113 to seal opening 113. Opening 113 and sealing plate 120 have a generally rectangular shape with the Y direction as the short side direction and the Z direction as the long side direction. The generally rectangular shape includes a rectangular shape or a substantially rectangular shape such as a rectangular shape with rounded corners.

[0039] A negative electrode terminal 301 (first electrode terminal) is provided on the sealing plate 120. The position of the negative electrode terminal 301 can be changed as appropriate. The negative electrode terminal 301 is exposed to the outside of the sealing plate 120.

[0040] 4, an opening 114 (second opening) is provided at the end of case body 110 on the +X side in the X direction. Opening 114 is located at the end opposite opening 113, and openings 113 and 114 face each other. Opening 114 is sealed with sealing plate 130 (second sealing plate). A joint 115 is formed in opening 114 to seal opening 114. Opening 114 and sealing plate 130 have a substantially rectangular shape with the Y direction as the short side direction and the Z direction as the long side direction.

[0041] A positive electrode terminal 302 (second electrode terminal) and a liquid injection hole 134 are provided on the sealing plate 130. The positions of the positive electrode terminal 302 and the liquid injection hole 134 can be changed as appropriate.

[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 (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.

[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 (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.

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

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

[0066] 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.

[0067] 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.

[0068] 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.

[0069] The current collector 431 (first current collector) to which the negative electrode tab group 220 is joined is made of a laminate (first laminate) in which a plurality of metal plates 4300 (see FIG. 20 ) described below are stacked. The current collector 441 (second current collector) to which the positive electrode tab group 250 is joined is made of a laminate (second laminate) in which a plurality of metal plates 4300 are stacked.

[0070] The current collector 432 (third current collector) to which the negative electrode tab group 270 is joined is made of a laminate (third laminate) in which a plurality of metal plates 4300 (see FIG. 20) are stacked. The current collector 442 (fourth current collector) to which the positive electrode tab group 280 is joined is made of a laminate (fourth laminate) in which a plurality of metal plates 4300 (see FIG. 20) are stacked.

[0071] 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 are joined to the current collectors 410, 420 in a folded state at folding portions (first to fourth folding portions) formed along the Z direction (first direction), and are electrically connected to the negative electrode terminal 301 and the positive electrode terminal 302.

[0072] 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).

[0073] 11, the current collectors 431, 432 are joined to the current collector 410 (first conductive member) at a portion where the current collectors 431, 432 overlap each other. In the example of Fig. 12, the current collectors 441, 442 are joined to the current collector 420 (second conductive member) at a portion where the current collectors 441, 442 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, 432, 441, 442 may be joined to the current collectors 410, 420 at positions spaced apart or adjacent to each other on the current collectors 410, 420.

[0074] The negative electrode tab group 220 and the negative electrode tab group 270 are joined to current collectors 431 and 432 at joints 431A and 432A (see FIG. 14) described below, respectively. The positive electrode tab group 250 and the positive electrode tab group 280 are joined to current collectors 441 and 442 at joints 441A and 442A (see FIG. 15) described below, respectively. The joints 431A, 432A, 441A, and 442A can be formed by, for example, ultrasonic bonding, resistance welding, laser welding, caulking, or the like.

[0075] 11, joint portion 431A between current collector 431 and negative electrode tab group 220 and joint portion 432A between current collector 432 and negative electrode tab group 270 are formed at positions spaced apart from each other on the XY plane. In other words, when viewed from the Z direction, joint portions 431A and 432A are spaced apart from each other.

[0076] 12, joint portion 441A between current collector 441 and positive electrode tab group 250 and joint portion 442A between current collector 442 and positive electrode tab group 280 are formed at positions spaced apart from each other on the XY plane. In other words, when viewed from the Z direction, joint portions 441A and 442A are spaced apart from each other.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] (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.

[0082] As shown in FIG. 13, the method for manufacturing the secondary battery 1 includes steps (S1, S2) of preparing the first electrode body 201 and the second electrode body 202, a step (S3) of joining the negative electrode tab group 220 and the negative electrode tab group 270 to the current collector 430, a step (S4) of joining the positive electrode tab group 250 and the positive electrode tab group 280 to the current collector 440, a step (S5) of overlapping the first electrode body 201 and the second electrode body 202, and a step (S6) of connecting the current collector 430 joined to the negative electrode tab group 220 and the negative electrode tab group 270 to the negative electrode terminal 3. 01 (S6), 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 collector 440 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 performing a leak test.

[0083] 14 to 19 are diagrams showing the steps in the method for manufacturing the secondary battery 1. FIG.

[0084] 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 lengths of the tips are the same when bundled.

[0085] 14 and 15, after the first electrode body 201 and the second electrode body 202 are fabricated, the negative electrode tab group 220 is joined to the current collector 431, and the negative electrode tab group 270 is joined to the current collector 432 (S3). In addition, the positive electrode tab group 250 is joined to the current collector 441, and the positive electrode tab group 280 is joined to the current collector 442 (S4).

[0086] The negative electrode tab group 220 is joined to the current collector 431 at a joint 431A. The negative electrode tab group 270 is joined to the current collector 432 at a joint 432A. The positive electrode tab group 250 is joined to the current collector 441 at a joint 441A. The positive electrode tab group 280 is joined to the current collector 442 at a joint 442A.

[0087] 14 and 15 , in the height direction of the first electrode body 201 and the second electrode body 202, the current collectors 431, 432, 441, 442 are arranged 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 biased to one side from the center of the first electrode body 201 and the second electrode body 202.

[0088] However, the scope of the present technology is not limited thereto, and the current collectors 431, 432, 441, 442 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.

[0089] As shown in FIG. 16, the first electrode body 201 and the second electrode body 202 are overlapped in the thickness direction of the first electrode body 201 and the second electrode body 202 (S5).

[0090] 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.

[0091] 16 , current collectors 431, 432 joined to negative electrode tab group 220 and negative electrode tab group 270 are assembled to sealing plate 120. Current collector 410 and negative electrode terminal 301 are attached to sealing plate 120 in advance. Current collectors 431, 432 are assembled to sealing plate 120 via current collector 410. The joints between current collectors 431, 432 and current collector 410 can be formed by, for example, laser welding. As a result of the above, current collector 430 is electrically connected to negative electrode terminal 301 (S6).

[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 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.

[0094] 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 440 side at the top (S8).

[0095] 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.

[0096] Furthermore, the electrode assembly 200 may be inserted into the case body 110 with the current collector 430 side (negative electrode side) first, inversely to the above example. In this case, the sealing plate 120 is assembled after the electrode assembly 200 is inserted into the case body 110.

[0097] As shown in FIG. 18 , after the electrode assembly 200 is inserted 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 current collector 440 is joined to the current collector 420 at a joint 420A. The joint 420A 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 (S9).

[0098] The current collectors 441, 442 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 441, 442 are bent simultaneously, but the current collectors 441, 442 may be bent sequentially.

[0099] 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.

[0100] 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.

[0101] 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 joining steps (S3, S4) of the current collectors 431, 432, 441, 442 can be changed as appropriate.

[0102] 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 440 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).

[0103] In this embodiment, an example has been described in which current collectors 431, 432 are bent after step (S6) of electrically connecting current collectors 431, 432 to negative electrode terminal 301, and current collectors 441, 442 are bent after step (S9) of electrically connecting current collectors 441, 442 to positive electrode terminal 302. However, current collectors 431, 432 may be deformed before step (S6) of electrically connecting current collectors 431, 432 to negative electrode terminal 301, or current collectors 441, 442 may be deformed before step (S9) of electrically connecting current collectors 441, 442 to positive electrode terminal 302.

[0104] (Configuration of metal plate 4300 and current collectors 430, 440) Although FIG. 20 exemplarily illustrates a metal plate 4300 constituting the negative electrode side current collector 430, a similar configuration can also be applied to the positive electrode side current collector 440.

[0105] As shown in FIG. 20, the metal plate 4300 includes a first region 430A joined to the negative electrode tab group 220, 270 (or the positive electrode tab group 250, 280), a second region 430B joined to the current collector 410, and a connection portion 430C, a hole portion 430D, and a notch 430E provided between the first region 430A and the second region 430B.

[0106] When forming the current collector 430, the plurality of metal plates 4300 may be bonded to one another in the first region 430A and the second region 430B. The bonding of the plurality of metal plates 4300 is preferably performed by, for example, ultrasonic bonding, diffusion bonding, or the like. In the case of diffusion bonding, the metal plates 4300 are preferably bonded to one another by applying pressure to the stacked metal plates 4300 while being heated at a temperature lower than the melting point of the metal plates 4300. The bonding of the plurality of metal plates 4300 to one another is performed before other conductive members (current collectors 410, 420) are bonded to the first region 430A and the second region 430B.

[0107] The connection portion 430C of the current collector 430 preferably includes a region where the multiple metal plates 4300 are not joined to one another. This makes it easier to bend the current collectors 430, 440 at the connection portion 430C. The bent portion of the metal plate 4300 preferably includes a region where the multiple metal plates 4300 are not joined to one another. Furthermore, it is 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 where the multiple metal plates 4300 are not joined to one another in regions other than the connection portion 430C (the first region 430A and the second region 430B).

[0108] 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.

[0109] 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 collectors 430, 440 at connection portion 430C. Connection portion 430C can also function as a fuse portion.

[0110] When used as a negative electrode current collector 430, metal plate 4300 can be made of, for example, copper or a copper alloy. When used as a positive electrode current collector 440, metal plate 4300 can be made of, for example, aluminum or an aluminum alloy. Metal plate 4300 can also be made of nickel, a nickel alloy, iron, or an iron alloy.

[0111] The thickness of one metal plate 4300 constituting the current collectors 430, 440 can be changed as appropriate. The thicker the metal plate 4300, the stronger the current collectors 430, 440 and the better the welding quality at the joints. On the other hand, the thinner the metal plate 4300, the easier it is to bend the current collectors 430, 440. 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. It is also 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.

[0112] It is preferable that the thickness (first plate thickness) of each metal plate 4300 included in the negative electrode side current collector 430 is equal to or less than (the same as or less than) the thickness (second plate thickness) of each metal plate 4300 included in the positive electrode side current collector 440.

[0113] The thickness of each metal plate 4300 included in the negative electrode current collector 430 is preferably, for example, about 0.05 mm or more, more preferably about 0.08 mm or more, and preferably about 0.2 mm or less, and more preferably about 0.12 mm or less. The thickness of each metal plate 4300 included in the positive electrode current collector 440 is, for example, preferably about 0.08 mm or more, more preferably about 0.12 mm or more, and preferably about 0.25 mm or less, and more preferably about 0.18 mm or less.

[0114] When used as the negative electrode side current collector 430, the thickness of one metal plate 4300 is preferably larger than the thickness of one negative electrode tab 230, and is preferably about three times or more (more preferably about five times or more) the thickness of one negative electrode tab 230.

[0115] When used as the positive electrode side current collector 440, the thickness of one metal plate 4300 is preferably larger 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.

[0116] The Young's modulus of copper or copper alloy used on the negative electrode side is greater than that of aluminum or aluminum alloy used on the positive electrode side. Furthermore, when a fuse portion is formed at the bent portion of metal plate 4300 on the positive electrode side, the cross-sectional area of ​​that portion is small, making current collectors 441 and 442 on the positive electrode side relatively easy to bend. Therefore, when the negative electrode side and positive electrode side have the same number of layers and the same plate thickness, current collectors 431 and 432 on the negative electrode side are more difficult to bend than current collectors 441 and 442 on the positive electrode side.

[0117] By making the thickness of one metal plate 4300 on the negative electrode side smaller than the thickness of one metal plate 4300 on the positive electrode side, it becomes easier to bend the current collector 430 on the negative electrode side. In addition, it is possible to prevent a large difference in the reaction force (the force trying to return to the original shape) of the current collectors 430, 440 stored in the case 100 in a bent state from occurring between the positive electrode side and the negative electrode side.

[0118] The number of layers of metal plates 4300 constituting current collectors 430, 440 can be changed as needed. The resistance can be kept low as the number of layers of metal plates 4300 increases. On the other hand, the current collectors 430, 440 can be easily bent as the number of layers of metal plates 4300 decreases.

[0119] The number of stacked metal plates 4300 in the negative electrode current collector 430 is two or more, preferably three or more, and more preferably four or more. It can be, for example, 20 or less, preferably 15 or less, and more preferably 10 or less. The number of stacked metal plates 4300 in the positive electrode current collector 440 is two or more, preferably three or more, and more preferably four or more. It can be, for example, 20 or less, preferably 15 or less, and more preferably 10 or less. The number of stacked metal plates 4300 (first stacking number) included in the negative electrode current collector 430 is preferably greater than or equal to the number of stacked metal plates 4300 (second stacking number) included in the positive electrode current collector 440.

[0120] The lamination thickness of current collector 430 (first thickness: T1) is preferably greater than the total thickness of negative electrode tab groups 220 and 270 joined to current collector 430 (second thickness: T2).

[0121] The lamination thickness of current collector 440 (first thickness: T1) is preferably greater than the total thickness of positive electrode tab groups 250, 280 joined to current collector 440 (second thickness: T2).

[0122] More preferably, T1 / T2 is about 1.5 or more, and even more preferably, T1 / T2 is about 2 or more. This results in a secondary battery with low resistance.

[0123] The "lamination thickness of the current collectors 430, 440" refers to the total thickness of the portions of the current collectors 430, 440 where there are no irregularities. The "total thickness of the negative electrode tab groups 220, 270 and the positive electrode tab groups 250, 280" refers to the total thickness of the portions where the negative electrode tab groups 220, 270 and the positive electrode tab groups 250, 280 are gathered together, excluding the joint portions 431A, 432A, 441A, 442A.

[0124] The lamination thickness (first lamination thickness) of each of the negative electrode side current collectors 431, 432 is preferably equal to or less than (the same as or less than) the lamination thickness (second lamination thickness) of each of the positive electrode side current collectors 441, 442.

[0125] Copper or copper alloy metal plate 4300 used on the negative electrode side is more difficult to weld to other conductive members than aluminum or aluminum alloy metal plate 4300 used on the positive electrode side. Here, by making the lamination thickness of negative electrode side current collector 430 smaller than the lamination thickness of positive electrode side current collector 440, it is possible to facilitate welding between negative electrode side current collector 430 and current collector 410.

[0126] Furthermore, since the resistivity of copper or copper alloy is lower than that of aluminum or aluminum alloy, even if the lamination thickness of the negative electrode side current collector 430 is small, the resistance value of the current collector 430 is prevented from becoming excessively high.

[0127] Furthermore, since the negative electrode tab groups 220, 270 are thinner than the positive electrode tab groups 250, 280, even if the lamination thickness of the negative electrode side current collector 430 is made smaller than the lamination thickness of the positive electrode side current collector 440, it is easy to keep the lamination thickness of the current collector 430 greater than that of the negative electrode tab groups 220, 270.

[0128] The shapes of the metal plate 4300 on the negative electrode side and the positive electrode side may be the same or different. Since the connection area of ​​the connection portion 430C of the metal plate 4300 is locally small, when the connection portion 430C is made to function as a fuse portion, it is preferable that the connection area of ​​the connection portion 430C (second portion) of the metal plate 4300 on the positive electrode side is equal to or less than the connection area of ​​the connection portion 430C (first portion) of the metal plate 4300 on the negative electrode side.

[0129] Metal plate 4300 made of aluminum or an aluminum alloy used on the positive electrode side tends to have a lower melting point and a higher resistance value than metal plate 4300 made of copper or a copper alloy used on the negative electrode side, and therefore, the fuse portion is preferably provided on positive electrode side current collector 440. Here, by reducing the conductive area of ​​connection portion 430C of metal plate 4300 on positive electrode side current collector 440, connection portion 430C on the positive electrode side can function stably as a fuse portion.

[0130] Note that the various points regarding the metal plate 4300 described with reference to Figure 20 can be applied similarly when the electrode body 200 is constructed from a single electrode body, i.e., when there is only one electrode tab group on the negative electrode side and one on the positive electrode side, and can also be applied similarly when the electrode body is constructed from three or more electrode bodies.

[0131] In FIG. 21, negative electrode tab group 220 and current collector 431 are in an unfolded state before being folded.

[0132] As shown in FIG. 21, current collector 431 is joined to current collector 410 at joint 410A, and is joined to negative electrode tab group 220 at joint 431A.

[0133] 21, when the distance between joint portion 410A and joint portion 431A in the vertical direction in the figure is L1 and the distance between the end of the main body portion of first electrode body 201 (the base portion of negative electrode tab group 220) and joint portion 410A is L2, it is preferable that L1>L2. A similar relationship of L1>L2 can also be established for other current collectors 432, 441, 442.

[0134] By making the distance between joint portion 410A and joint portion 431A relatively large, it is possible to reduce the tensile stress generated in negative electrode tab group 220 when current collector 431 is bent, and more effectively prevent breakage or damage to negative electrode tab group 220. As described above, by maintaining the relationship L1>L2, it is possible to protect negative electrode tab group 220.

[0135] In this embodiment, the negative electrode side current collector 430 is joined to the current collector 410 and bent before inserting the electrode assembly 200 into the case body 110, and the positive electrode side current collector 440 is joined to the current collector 420 and bent after inserting the electrode assembly 200 into the case body 110. For this reason, it is preferable that the positive electrode side current collector 440 has a slightly larger L1 than the negative electrode side current collector 430. That is, it is preferable that the separation distance L1 between the joint portion 410A and the joint portion 431A of the negative electrode side current collector 430 is smaller than that of the positive electrode side current collector 440. Similarly, it is preferable that the separation distance L2 between the base of the tab group and the joint portion of the negative electrode tab groups 220 and 270 is smaller than that of the positive electrode tab groups 250 and 280.

[0136] Furthermore, it is preferable that the length corresponding to L3 in FIG. 21 be shorter for the positive electrode side current collector 440 compared to the negative electrode side current collector 430. This is because the positive electrode side current collector 440 is joined to the current collector 420 (another conductive member) in a state in which the electrode assembly 200 is inserted into the case body 110, and therefore by making L3 relatively long, it is possible to more stably join the current collector 440 and the current collector 420. It is preferable that the current collector 440 is joined to the current collector 420 shifted toward the end side (lower side in terms of the positional relationship in FIG. 21) from the center.

[0137] Note that L1 and L2 in FIG. 21 are determined by the shortest metal plate 4300 among the multiple metal plates 4300 constituting the current collector 430 and the shortest negative electrode tab 230 among the multiple negative electrode tabs 230 constituting the negative electrode tab group 220.

[0138] 22 , the bending angle of current collector 431 can be defined as an intersection angle θ between plane A including joint portion 410A with current collector 410 and plane B including joint portion 431A with negative electrode tab group 220. The bending angles of other current collectors 432, 441, and 442 can be defined in the same way as current collector 431.

[0139] The bending angle (θ) of current collectors 430, 440 is preferably about 90° or less, more preferably about 45° or less, and even more preferably about 30° or less. The bending angle (first bending angle) of negative electrode side current collector 430 is preferably equal to or less than (the same as or less than) the bending angle (second bending angle) of positive electrode side current collector 440.

[0140] Furthermore, it is preferable that the minimum curvature of the bent portion (second bent portion) of the positive electrode side current collector 441 is equal to or less than the minimum curvature of the bent portion (first bent portion) of the negative electrode side current collector 431, and it is preferable that the minimum curvature of the bent portion (fourth bent portion) of the positive electrode side current collector 442 is equal to or less than the minimum curvature of the bent portion (third bent portion) of the negative electrode side current collector 432.

[0141] The current collector 440 on the positive electrode side tends to have a greater laminate thickness than the current collector 430 on the negative electrode side. Therefore, by reducing the minimum curvature of the folded portion of the current collector 440, it is possible to prevent the current collector 440 from becoming too long in the X direction after folding, thereby achieving space saving.

[0142] In the present embodiment, by using current collectors 430, 440 formed of a laminate of multiple metal plates 4300, 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.

[0143] Furthermore, in the present embodiment, in a state in which 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 curved in the same direction. This makes it possible to efficiently utilize the space inside the curved portions of the current collector 431 (negative electrode side) and the current collector 441 (positive electrode side) to arrange the current collectors 432 and 442. As a result, the negative electrode current collector 400A and the positive electrode current collector 400B can be further miniaturized, and the energy density of the secondary battery 1 can be improved.

[0144] Furthermore, in the present embodiment, when the negative electrode side current collector 430 is made of copper or a copper alloy, the negative electrode side current collector 430, which is relatively difficult to bend, can be bent at a stage before inserting the electrode assembly 200 into the case body 110. This allows the current collector 430 to be bent relatively stably without being hindered by the case body 110. As a result, the shape and bent state of the current collector 430 are stabilized. Furthermore, it is possible to prevent unintended loads from being applied to the negative electrode tab groups 220 and 270, thereby preventing damage to the negative electrode tab groups 220 and 270. On the other hand, when the positive electrode side current collector 440 is made of aluminum or an aluminum alloy, the positive electrode side current collector 440 is relatively easy to bend. Therefore, as exemplified in this embodiment, even when the current collector 440 is bent while the electrode assembly 200 is disposed in the case body 110, the current collector 440 can be bent stably, thereby preventing unintended loads from being applied to the positive electrode tab groups 250 and 280.

[0145] Furthermore, in the present embodiment, by previously joining the current collectors 430, 440 to the negative electrode tab groups 220, 270 and the positive electrode tab groups 250, 280 (S3, S4), it is possible to protect the negative electrode tab groups 220, 270 and the positive electrode tab groups 250, 280 and suppress damage thereto (deformation, tearing, etc.) in the subsequent step (S5) 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.

[0146] (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.

[0147] 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).

[0148] 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.

[0149] 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.

[0150] 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]

[0151] 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 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, 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, a first current collector to which the first electrode tab is joined; a second current collector to which the second electrode tab is joined, the first current collector is made of a first laminate in which a plurality of metal plates are laminated, and has a first bent portion; the second current collector is made of a second laminate in which a plurality of metal plates are stacked, and has a second folded portion.

2. a second electrode body including the first electrode and the second electrode and housed in the case; 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 third current collector to which the third electrode tab is joined; a fourth current collector to which the fourth electrode tab is joined, the third current collector is made of a third laminate in which a plurality of metal plates are laminated, and has a third folded portion; The secondary battery according to claim 1 , wherein the fourth current collector is made of a fourth laminate in which a plurality of metal plates are laminated, and has a fourth folded portion.

3. the first electrode body and the second electrode body are disposed in the case in a state where they are stacked on top of each other; the first current collector and the third current collector are connected to a first conductive member; The secondary battery according to claim 2 , wherein the second current collector and the fourth current collector are connected to a second conductive member.

4. the first current collector and the third current collector are curved in the same direction as each other, The secondary battery according to claim 2 or 3, wherein the second current collector and the fourth current collector are curved in the same direction as each other.

5. the first bent portion, the second bent portion, the third bent portion, and the fourth bent portion are formed along a first direction; when viewed from the first direction, a portion of the first current collector to which the first electrode tab is joined and a portion of the third current collector to which the third electrode tab is joined are formed at positions spaced apart from each other, 4. The secondary battery according to claim 2, wherein, when viewed from the first direction, a portion of the second current collector to which the second electrode tab is joined and a portion of the fourth current collector to which the fourth electrode tab is joined are formed at positions spaced apart from each other.

6. the first electrode is a negative electrode and the second electrode is a positive electrode; each of the plurality of metal plates constituting the first current collector has a first plate thickness; each of the plurality of metal plates constituting the second current collector has a second plate thickness; The secondary battery according to claim 1 , wherein the first plate thickness is smaller than the second plate thickness.

7. the first electrode is a negative electrode and the second electrode is a positive electrode; the first current collector has a first lamination thickness; the second current collector has a second lamination thickness; The secondary battery according to claim 1 , wherein the first laminate thickness is smaller than the second laminate thickness.

8. the first electrode is a negative electrode and the second electrode is a positive electrode; the first current collector has a first portion having a locally small conduction area; the second current collector has a second portion having a locally small conduction area; The secondary battery according to claim 1 , wherein a conductive area of ​​the second portion is smaller than a conductive area of ​​the first portion.

9. the first electrode is a negative electrode and the second electrode is a positive electrode; The secondary battery according to claim 1 , wherein the minimum curvature of the second bent portion is smaller than the minimum curvature of the second bent portion.

10. a first electrode body 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, 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, 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 including a second laminate in which a plurality of metal plates are laminated, to which the second electrode tab is joined; a first conductive member joined to the first current collector; a second conductive member joined to the second current collector, joining the first electrode tab to the first current collector; connecting the first current collector connected to the first electrode tab to the first conductive member; bending the first current collector between a portion of the first current collector joined to the first electrode tab and a portion of the first current collector joined to the first conductive member; joining the second electrode tab to the second current collector; connecting the second current collector connected to the second electrode tab to the second conductive member; bending the second current collector between a portion of the second current collector joined to the second electrode tab and a portion of the second current collector joined to the second conductive member.

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