Secondary battery and method for manufacturing secondary battery

Abstract

To provide a method for manufacturing a secondary battery with a configuration capable of suppressing occurrence of damage to a tab group.SOLUTION: The method for manufacturing a secondary battery 1 includes: a preparation step of preparing a current collector 53A as a first laminated body in which a plurality of metal plates are laminated, the current collector 53A including a first region 532A and a second region 532B, being configured such that a positive electrode tab group is joined to the first region 532A and a positive electrode current collecting portion is joined to the second region 532B, and having a first joint portion 532T in which the metal plates are partially joined to each other; a first tab group connecting step of joining the positive electrode tab group to the current collector 53A; and another conductive member connecting step of joining the positive electrode current collecting portion to the current collector 53A.SELECTED DRAWING: Figure 25

Description

[Technical Field]

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

[0002] Japanese Patent Laid-Open Publication No. 2021-099936 (Patent Document 1) relates to an invention of an electricity storage device, and discloses a configuration in which a group of tabs connected to a current collector are bent. Japanese Patent No. 5337586 (Patent Document 2) and Japanese Patent No. 4120353 (Patent Document 3) disclose using a metal plate laminate as a current collector. It is disclosed that a portion of the metal plate laminate that has been ultrasonically bonded in advance is laser welded to another conductive member. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-099936 [Patent Document 2] Patent No. 5337586 [Patent Document 3] Patent No. 4120353 Summary of the Invention [Problem to be solved by the invention]

[0004] To achieve a structure in which the tab group is bent, the length of the tab group needs to be increased, which may result in unintended folds or bends in the tab group during the secondary battery manufacturing process, etc., and may result in damage to the tab group.

[0005] An object of the present technology is to provide a secondary battery having a configuration capable of suppressing damage to a tab group, and a method for manufacturing the secondary battery. [Means for solving the problem]

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

[0007] [1] A method for manufacturing a secondary battery comprising: an electrode assembly including a first electrode and a second electrode having a polarity different from that of the first electrode; a case for accommodating the electrode assembly; a first tab group including a plurality of stacked first electrode tabs electrically connected to the first electrode; and a first current collector connected to the first tab group, wherein the first current collector is a first laminate including a plurality of stacked metal plates, and the first current collector includes a first region and a second region, the first tab group being joined to the first region and another conductive member being joined to the second region, the method comprising: a preparation step for preparing the first current collector having a joint where the metal plates are partially joined together; a first tab group connection step for joining the first tab group to the first region; and an other conductive member connection step for joining the other conductive member to the second region.

[0008] [2] The method for manufacturing a secondary battery according to [1], further comprising, after the first tab group connecting step and the other conductive member connecting step, a step of bending the first current collector between the first region and the second region.

[0009] [3] A method for manufacturing a secondary battery according to [1] or [2], comprising the step of irradiating the joint where the metal plates are joined in the first current collector with high-energy rays, thereby joining the first current collector and the other conductive member.

[0010] [4] The method for manufacturing a secondary battery according to [3], wherein the other conductive member has a convex portion, and the method includes a step of irradiating the first current collector, which is disposed on the convex portion, with the high-energy ray to bond the first current collector and the convex portion.

[0011] [5] The method for manufacturing a secondary battery according to any one of [1] to [4], further comprising the step of irradiating a region of the first current collector where the metal plates are not joined with high-energy rays, thereby joining the first current collector and the other conductive member.

[0012] [6] The method for manufacturing a secondary battery according to [5], further comprising a step of carrying out the process in a state in which the first current collector is pressed against the other conductive member by a jig around the area to be irradiated with the high-energy rays.

[0013] [7] A method for manufacturing a secondary battery according to any one of [1] to [6], comprising a step of abutting the first tab group against the joint portion of the first current collector where the metal plates are joined together, thereby joining the first current collector and the first tab group.

[0014] [8] A method for manufacturing a secondary battery according to any one of [1] to [7], comprising a step of abutting the first tab group against an area of ​​the first current collector where the metal plates are not joined to each other, thereby joining the first current collector and the first tab group.

[0015] [9] A secondary battery comprising: an electrode assembly including a first electrode and a second electrode having a polarity different from that of the first electrode; a case that houses the electrode assembly; a first tab group in which a plurality of first electrode tabs electrically connected to the first electrode are stacked; and a first current collector connected to the first tab group, wherein the first current collector is a first laminate in which a plurality of metal plates are stacked, the first current collector includes a first region and a second region, the first tab group is joined to the first region and another conductive member is joined to the second region, and the first current collector has a region in which the metal plates are joined to each other, other than a portion joined to the first tab group and a portion joined to the other conductive member.

[0016]

[10] The secondary battery described in [9], wherein the first current collector has a first bonding region where the metal plates are bonded together, and a second bonding region where the first current collector and the other conductive member are laser-welded, and when viewed along the stacking direction of the metal plates, the area of ​​the first bonding region is larger than the area of ​​the second bonding region.

[0017]

[11] The secondary battery according to

[10] , wherein the second junction region is provided within the first junction region.

[0018]

[12] The secondary battery according to any one of [9] to

[11] , wherein the first current collector has a plurality of first recesses on a first outer surface, which is one of the outer surfaces, and a joint between the first current collector and the other conductive member is formed linearly along the first recesses. [Effects of the Invention]

[0019] According to the present technology, a secondary battery having a configuration capable of suppressing damage to a group of tabs is provided. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a front view showing the configuration of a secondary battery according to a first embodiment. [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] FIG. 7 is a cross-sectional view of the negative electrode (cross-sectional view taken along VII-VII in FIG. 8). [Figure 8] FIG. [Figure 9] 11 is a cross-sectional view of the positive electrode (cross-sectional view taken along line IX-IX in FIG. 10). [Figure 10] FIG. [Figure 11] FIG. 2 is a diagram showing the peripheral configuration of a negative electrode current collector. [Figure 12] FIG. 2 is a diagram showing the configuration of the periphery of a positive electrode current collector. [Figure 13] 1 is a flowchart showing a method for manufacturing a secondary battery. [Figure 14] FIG. 2 is a diagram showing a state in which current collectors are joined to a first electrode body and a second electrode body. [Figure 15] FIG. 10 is a view showing a state in which a sealing plate is attached to a negative electrode-side current collector. [Figure 16] FIG. 2 is a diagram showing a state in which the first electrode body and the second electrode body are superimposed. [Figure 17] 10A and 10B are diagrams showing a process of inserting the first electrode body and the second electrode body into the case body. [Figure 18] FIG. 10 is a view showing a state in which a sealing plate is attached to a current collector on the positive electrode side. [Figure 19] FIG. 10 is a view showing a state in which the opening of the case body is sealed. [Figure 20] FIG. 2 is a diagram showing a metal plate constituting a current collector. [Figure 21] FIG. 10 is a development view of a current collector according to a second embodiment. [Figure 22] 22 is a cross-sectional view taken along the line XXII-XXII in FIG. 21. [Figure 23] 23 is a cross-sectional view taken along the line XXIII-XXIII in FIG. 21. [Figure 24] FIG. 24 is a cross-sectional view taken along the line XXIV-XXIV in FIG. 21. [Figure 25] FIG. 10 is a development view of a current collector according to a third embodiment. [Figure 26] FIG. 10 is a development view of a current collector according to a fourth embodiment. [Figure 27] FIG. 10 is a development view of a current collector according to a fifth embodiment. [Figure 28] FIG. 13 is a development view of a current collector according to a sixth embodiment. [Figure 29] FIG. 13 is a development view of a current collector according to a seventh embodiment. [Figure 30] FIG. 13 is a development view of a current collector according to an eighth embodiment. [Figure 31] FIG. 13 is a development view of a current collector according to a ninth embodiment. [Figure 32] FIG. 22 is a development view of the current collector of the tenth embodiment. [Figure 33] FIG. 22 is a development view of the current collector of the eleventh embodiment. [Figure 34] FIG. 23 is a development view of a current collector according to a twelfth embodiment. [Figure 35]FIG. 23 is a cross-sectional view showing a state during laser welding in accordance with the thirteenth embodiment. [Figure 36] FIG. 23 is a cross-sectional view showing the state during laser welding in accordance with the fourteenth embodiment. [Figure 37] FIG. 23 is a schematic plan view showing one ultrasonic bonding mark according to the fourteenth embodiment. [Figure 38] FIG. 23 is a plan view showing an example of ultrasonic bonding marks according to the fourteenth embodiment. [Figure 39] FIG. 23 is a plan view showing another example of ultrasonic bonding marks according to the fourteenth embodiment. [Figure 40] FIG. 23 is a plan view showing still another example of ultrasonic bonding marks according to the fourteenth embodiment. [Figure 41] FIG. 23 is a development view showing the joint between the second region of the current collector and the positive electrode tab group in the fifteenth embodiment. [Figure 42] FIG. 23 is a cross-sectional view of a bonding region provided in advance in a first region of a current collector according to a sixteenth embodiment. [Figure 43] FIG. 22 is a first schematic diagram showing a case where a positive electrode tab group is joined to a first region of a current collector in a sixteenth embodiment. [Figure 44] FIG. 23 is a second schematic diagram showing a case where a positive electrode tab group is joined to the first region of the current collector in the sixteenth embodiment. [Figure 45] FIG. 22 is a development view of a current collector according to a seventeenth embodiment. [Figure 46] FIG. 23 is a schematic diagram showing ultrasonic bonding between a positive electrode tab group and a first region according to a seventeenth embodiment. [Figure 47] FIG. 22 is a schematic diagram showing laser welding between the positive electrode current collector and the second region in the seventeenth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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).

[0025] 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.

[0026] 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.

[0027] 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.

[0028] (Embodiment 1: Overall Configuration of Battery) Fig. 1 is a front view of a secondary battery 1 according to embodiment 1. Figs. 2 to 5 are diagrams showing 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.

[0029] 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.

[0030] 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 .

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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 .

[0055] 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).

[0056] 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).

[0057] (Configuration of electrode body 200) 7 and 8, the negative electrode 210 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.

[0058] 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.

[0059] 9 and 10, the positive electrode 240 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] (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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] Negative electrode tab group 220 and negative electrode tab group 270 are curved in opposite directions so that their leading ends approach each other.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] 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 positive electrode current collecting portion 420 in a folded state, and are electrically connected to the positive electrode terminal 302.

[0079] 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).

[0080] 12, the current collectors 431, 432 are joined to the positive electrode current collecting part 420 at a portion where the current collectors 431, 432 overlap each other (joining region 420A in FIG. 18). However, the scope of the present technology is not limited thereto, and the current collectors 431, 432 may be joined to the positive electrode current collecting part 420 at positions spaced apart or adjacent to each other on the positive electrode current collecting part 420.

[0081] The positive electrode tab group 250 and the positive electrode tab group 280 are respectively joined to current collectors 431, 432 in a positive electrode joining region 200R (see FIG. 14) described later. The positive electrode joining region 200R can be formed by, for example, ultrasonic joining, resistance welding, laser welding, caulking, or the like.

[0082] The positive electrode bonding region 200R between the current collector 431 and the positive electrode tab group 250 and the positive electrode bonding region 200R between the current collector 432 and the positive electrode tab group 280 are formed at positions spaced apart from each other on the XY plane.

[0083] 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.

[0084] 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.

[0085] 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.

[0086] (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.

[0087] 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.

[0088] 14 to 19 are diagrams showing the steps in the method for manufacturing the secondary battery 1. FIG.

[0089] 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.

[0090] 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).

[0091] The negative electrode tab groups 220, 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 in the positive electrode joining region 200R. The positive electrode tab group 280 is joined to the current collector 432 in the positive electrode joining region 200R.

[0092] 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.

[0093] 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.

[0094] 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.

[0095] 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).

[0096] 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.

[0097] 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.

[0098] 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.

[0099] 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).

[0100] 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.

[0101] 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. A positive electrode current collecting part 420 and a 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 positive electrode current collecting part 420. The current collector 430 is joined to the positive electrode current collecting part 420 in a joining region 420A. The joining region 420A can be formed by, for example, laser welding. As a result of the above, the current collector 430 is electrically connected to the positive electrode terminal 302 (S9).

[0102] 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.

[0103] 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.

[0104] 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.

[0105] 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.

[0106] 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).

[0107] 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.

[0108] (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 positive electrode current collecting portion 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.

[0109] 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 positive electrode current collecting portion 420) are bonded to the first region 430A and the second region 430B.

[0110] 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.

[0111] 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.

[0112] 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.

[0113] The metal plate 4300 can be made of, for example, aluminum or an aluminum alloy. The metal plate 4300 can also be made of copper, a copper alloy, nickel, a nickel alloy, iron, or an iron alloy. The thickness of one metal plate 4300 is preferably greater than the thickness of one positive electrode tab 260, and is preferably about three times or more (more preferably about five times or more) the thickness of one positive electrode tab 260. The thickness of one metal plate 4300 is preferably, for example, 0.05 mm or more, and more preferably 0.08 mm or more. It is also preferably 0.5 mm or less, more preferably 0.3 mm or less, and even more preferably 0.2 mm or less. The thickness of one metal plate 4300 is preferably ½ or less, and more preferably ⅕ or less, of the thickness of the positive electrode current collecting part 420. The same can be applied when a current collector in which metal plates are stacked is used on the negative electrode side.

[0114] 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.

[0115] 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 and other than the positive electrode bonding region 200R.

[0116] 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.

[0117] 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.

[0118] 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.

[0119] 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.

[0120] 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.

[0121] (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.

[0122] 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.

[0123] 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.

[0124] 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.

[0125] Next, in the following embodiments, specific configurations of the current collectors used for the first and second current collectors described above will be described. Since the first and second current collectors have the same shape, the configuration of the first current collector will be described below.

[0126] (Embodiment 2: Configuration of current collector 53) In the above-described first embodiment, the length of the second region 430B joined to the positive electrode current collector 420 is longer than the length (vertical direction in the drawing) of the first region 430A joined to the positive electrode tab groups 250, 280, but this length relationship is not necessarily limited to this. The current collector described below is one in which the length (vertical direction in the drawing) of the first region 430A joined to the positive electrode tab groups 250, 280 is longer than the length of the second region 430B joined to the positive electrode current collector 420. Note that descriptions of parts common to the first embodiment will be omitted.

[0127] The configuration of current collector 53 will be described with reference to Figures 21 to 24. Figures 21 and 25 are developments showing the state of current collector 53 before it is folded.

[0128] The current collector 53 is formed by laminating a plurality of metal plates 4300. The current collector 53 includes a first region 532A connected to the positive electrode tab group 250 and a second region 532B connected to the positive electrode current collecting portion 420 as another conductive member.

[0129] A first fuse portion 532C and a second fuse portion 532D are provided between the first region 532A and the second region 532B as connections that melt when a current equal to or greater than a predetermined value flows. The widths of the first fuse portion 532C and the second fuse portion 532D are set smaller than the width of the second region 532B.

[0130] A first hole 532E is provided between the first fuse portion 532C and the second fuse portion 532D. Inwardly recessed, U-shaped first cutouts 532F are provided on both end sides of the first fuse portion 532C and the second fuse portion 532D.

[0131] (bonded state) Before being connected to the tab group of the electrode body 200, no bonding area between the metal plates is provided in advance in either the first region 532A or the second region 532B. The illustration shows a bonding portion 532R when the positive electrode tab groups 250, 280 are connected to the first region 532A, and a bonding portion 532S when the positive electrode current collector 420 is connected to the second region 532B.

[0132] In the case of current collector 53 in this embodiment, before being joined to positive electrode tab groups 250, 280 and positive electrode current collecting portion 420, there are no joints.

[0133] In the following, only the differences between the current collectors of Embodiments 3 to 17 and those of Embodiment 2 will be described.

[0134] (Embodiment 3: Current Collector 53A) With reference to FIG. 25, the bonding state of current collector 53A of the present embodiment will be described.

[0135] In the second region 532B of the current collector 53A, a joint 532T (first joint) between the metal plates is provided in advance by ultrasonic bonding, diffusion bonding, etc. The position where the joint 532T is provided is located at a position overlapping with the planned position of the joint 532S (second joint).

[0136] The joint portion 532S is provided inside the joint portion 532T, and the area of ​​the joint portion 532T is set to be larger than the area of ​​the joint portion 532S.

[0137] In this way, by providing the joint portion 532T in the second region 532B in advance, it is possible to facilitate handling of the current collector 53A on which the metal plate 4300 is laminated in the subsequent manufacturing process, as in the above embodiment.

[0138] Specifically, by including a process in which high-energy rays are irradiated to joint 532T where metal plates are joined in current collector 53A, and then current collector 53A and positive electrode current collecting part 420 are joined at joint 532S, current collector 53A and positive electrode current collecting part 420 can be stably joined.

[0139] In the joining process of the joint 532T, diffusion bonding is preferred because it is less likely to create multiple recesses on the surface of the joint. Diffusion bonding is a joining method in which metal plates are heated and pressurized at a temperature below their melting points. The thickness of the joint can be made (slightly) smaller than the sum of the thicknesses of the surrounding metal plates (total thickness of each metal plate).

[0140] Unlike ultrasonic bonding, diffusion bonding does not require the use of vibrations in the jigs that clamp the laminated metal sheets from both sides.Furthermore, ultrasonic bonding marks (irregularities) caused by the clamping action of the anvil and horn used in ultrasonic bonding are not produced, and the bonded surfaces can be made flat.

[0141] At joint 532T where the metal plates are joined together in advance, there is no gap between the metal plates, and therefore, when current collector 53A and positive electrode current collecting part 420 are welded by irradiating them with high-energy rays such as a laser, unintended damage (such as holes) to the metal plates is suppressed, and joint 532S can be stably formed.

[0142] In the third embodiment, the region of the first region 532A to which the positive electrode tab group 250 is joined (the portion that becomes the joint 532R) has no metal plate joined in advance before the first region 532A and the positive electrode tab group 250 are joined. As a result, when the positive electrode tab group 250 is ultrasonically joined to the first region 532A, when the first region 532A and the positive electrode tab group 250 are clamped between the anvil and the horn, the respective components are brought into contact in a more preferable state, and ultrasonic joining can be performed stably.

[0143] (Embodiment 4: Current Collector 53B) With reference to FIG. 26, the bonding state of current collector 53B of the present embodiment will be described.

[0144] In the second region 532B of the current collector 53B, a joint 532T between the metal plates is provided in advance by ultrasonic bonding, diffusion bonding, etc. The position where the joint 532T is provided is set at a position that does not overlap with the planned position of the joint 532S.

[0145] By providing bonding portion 532T in second region 532B in advance in this manner, current collector 53B on which metal plate 4300 is laminated can be easily handled in the subsequent manufacturing process.

[0146] Here, the surface of second region 532B is relatively flat in the region where the metal plates have not been previously joined together, which makes it easier for second region 532B and positive electrode current collecting portion 420 to abut against each other without any gaps, and joint portion 532S can be stably formed by laser welding or the like.

[0147] (Embodiment 5: Current Collector 53C) With reference to FIG. 27, the bonding state of current collector 53C of the present embodiment will be described.

[0148] In the first region 532A of the current collector 53C, a joint 532U (first joint region) between the metal plates is provided in advance by ultrasonic bonding, diffusion bonding, etc. The position where the joint 532U is provided is set at a position that does not overlap with the planned position of the joint 532R.

[0149] (Embodiment 6: Current Collector 53D) With reference to FIG. 28, the bonding state of current collector 53D of the present embodiment will be described.

[0150] In current collector 53D, first region 532A is provided with joint 532U between metal plates by ultrasonic bonding, diffusion bonding, or the like in advance. Joint 532U is provided at a position that does not overlap with the planned position of joint 532R. Second region 532B is provided with joint 532T between metal plates by ultrasonic bonding, diffusion bonding, or the like in advance. Joint 532T is provided at a position that does not overlap with the planned position of joint 532S.

[0151] (Embodiment 7: Current Collector 53E) Referring to FIG. 29, the bonding state of current collector 53E of the present embodiment will be described.

[0152] In the first region 532A of the current collector 53E, a joint 532U (first joint region) between the metal plates is provided in advance by ultrasonic bonding, diffusion bonding, etc. The position where the joint 532U is provided overlaps with the position where the joint 532R is planned to be provided.

[0153] The joint 532R (second joint region) is provided within the joint 532U (first joint region), and the area of ​​the joint 532U (first joint region) is set larger than the area of ​​the joint 532R (second joint region).

[0154] (Embodiment 8: Current Collector 53F) With reference to FIG. 30, the bonding state of current collector 53F of the present embodiment will be described.

[0155] In current collector 53F, first region 532A is provided with joint 532U between metal plates by ultrasonic bonding, diffusion bonding, or the like in advance. Joint 532U is provided at a position overlapping with a planned position for joint 532R. In second region 532B, joint 532T between metal plates is provided with ultrasonic bonding, diffusion bonding, or the like in advance. Joint 532T is provided at a position overlapping with a planned position for joint 532S.

[0156] (Summary of Embodiments 3 to 8) By forming a joint between the metal plates before joining other members (positive electrode tabs, positive electrode current collector, and other conductive members) to the current collector, which is a laminate of metal plates, handling in the subsequent manufacturing process can be facilitated. In addition, the joint between the current collector and other members can be stably formed, resulting in a secondary battery with high energy density and high reliability.

[0157] In addition, when the current collector is divided into regions at the boundary of a portion that will become a bent portion (e.g., a portion with a small cross-sectional area), it is preferable that the joint between only the metal laminates and the attachment portion to another conductive member (e.g., positive electrode current collecting portion 420) are located on the same region side.

[0158] (Embodiment 9: Current Collector 53G) The bonding state of current collector 53G of the present embodiment will be described with reference to Fig. 31. In current collector 53G, the area of ​​second region 532B is larger than the area of ​​first region 532A.

[0159] In current collector 53G, first region 532A is provided with joint 532U between metal plates by ultrasonic bonding, diffusion bonding, etc. Second region 532B is provided with joint 532T between metal plates by ultrasonic bonding, diffusion bonding, etc. Joint 532T is provided at a position that does not overlap with the planned position of joint 532S.

[0160] (Embodiment 10: Current Collector 53H) Referring to FIG. 32, the bonding state of current collector 53H of the present embodiment will be described.

[0161] In the first region 532A of the current collector 53H, a joint 532U between the metal plates is provided in advance by ultrasonic bonding, diffusion bonding, etc. The position where the joint 532U is provided is located at a position overlapping with the planned position of the joint 532R.

[0162] (Embodiment 11: Current Collector 53I) With reference to FIG. 33, the bonding state of current collector 53I of the present embodiment will be described.

[0163] In the first region 532A of the current collector 53I, a joint 532U between the metal plates is provided in advance by ultrasonic bonding, diffusion bonding, or the like. The position where the joint 532U is provided is a position overlapping with the planned position of the joint 532R. In the second region 532B, two joints 532T between the metal plates are provided in advance by ultrasonic bonding, diffusion bonding, or the like. One of the joints 532T is provided in a position overlapping with the planned position of the joint 532S.

[0164] (Summary of Embodiments 9 to 11) The method may include a step of ultrasonically joining the positive electrode tab group 250, 280 to form a joint 532R on one side of the joint 532T (first connection portion) where the metal plates are joined in the current collector, and then providing a joint 532S to which the positive electrode current collecting part 420 as another conductive member is joined by irradiating high-energy rays in a region in a different direction from the joint 532R where the positive electrode tab group 250, 280 is joined relative to the joint 532T.

[0165] It is preferable that no joint with the positive electrode current collecting portion 420 is provided between joint 532T, where the metal plates are previously joined together, and joint 532R, where the positive electrode tab groups 250, 280 are joined. It is preferable that joint 532T and joint 532S are aligned in the first direction, which is the longitudinal direction of the second region 532B.

[0166] Even if the metal plate constituting the current collector 53G is deformed or bent when the positive electrode tab groups 250, 280 are ultrasonically bonded to the current collector, the deformation and bending of the metal plate at the joint 532S where the positive electrode current collecting part 420 is bonded can be suppressed by irradiating high-energy rays, and therefore the current collector and the positive electrode current collecting part 420 can be stably bonded.

[0167] In the current collector, the joint 532R where the positive electrode tab groups 250, 280 are joined may be (1) metal plates joined together in advance (by ultrasonic bonding, etc.), or (2) metal plates may not be joined together in advance (by ultrasonic bonding, etc.).

[0168] In the current collector, the joint 532S to which the positive electrode current collecting part 420, which is another conductive member, is joined may be (1) metal plates joined together in advance (by ultrasonic bonding, etc.), or (2) metal plates may not be joined together in advance (by ultrasonic bonding, etc.).

[0169] When the current collector is unfolded (before being folded), the joint 532T (first connection portion) and the joint 532R where the positive electrode tab groups 250, 280 are joined may be arranged side by side in a second direction perpendicular to the first direction (within the plane in which the metal plate extends).

[0170] (Embodiment 12: Current Collector 53J) With reference to FIG. 34, the bonding state of current collector 53J of the present embodiment will be described.

[0171] Current collector 53J has joints 532U in first region 532A where metal plates are joined together by ultrasonic bonding, diffusion bonding, or the like. When forming joints 532U, the contours of joints 532U are elliptical, which makes it possible to suppress local stress concentration when force is applied to stacked current collectors 53J. This elliptical shape is also applicable to the above-described embodiments.

[0172] The manufacturing process of a secondary battery using current collectors 53A to 53J shown in the third to twelfth embodiments can include the following steps.

[0173] The manufacturing process for a secondary battery using current collectors 53A to 53J includes a preparation step of preparing a current collector (first current collector) having a joint where metal plates are partially joined together, a first tab group connection step of joining positive electrode tab groups 250, 280 (first tab group) to the first region, and an other conductive member connection step of joining positive electrode current collecting portion 420 (other conductive member) to the second region.

[0174] Furthermore, after the first tab group connecting step and the other conductive member connecting step, there is a step of bending the current collector between the first region and the second region.

[0175] The manufacturing process of a secondary battery using current collector 53A, current collector 53F, current collector 53H, and current collector 53I includes a step of irradiating a high-energy ray to the joint where the metal plates are joined in the current collector, thereby joining the current collector and positive electrode current collecting part 420.

[0176] The manufacturing process of a secondary battery using current collector 53B, current collector 53C, current collector 53D, current collector 53E, current collector 53G, and current collector 53H includes a step of irradiating a high-energy ray to an area where the metal plates are not joined together, thereby joining the second area of ​​the current collector and positive electrode current collecting portion 420.

[0177] The manufacturing process for a secondary battery using current collector 53E, current collector 53F, current collector 53H, current collector 53I, and current collector 53J includes a step of abutting positive electrode tab groups 250, 280 against the joint where the metal plates are joined, thereby joining the current collectors and positive electrode tab groups 250, 280.

[0178] The manufacturing process for a secondary battery using current collector 53B, current collector 53C, and current collector 53D includes a step of abutting positive electrode tab groups 250, 280 against the areas where the metal plates are not joined together, and joining the current collectors and positive electrode tab groups 250, 280.

[0179] (Embodiment 13) Next, with reference to FIG. 35, a case will be described in which a previously joined portion of a metal plate laminate is welded to another conductive member by irradiating it with a high-energy ray such as a laser.

[0180] 35, rib 700 is provided on positive current collecting part 420, and joint portion 532T of current collector 53F, which is a metal laminate, is pressed against positive current collecting part 420 including rib 700, and laser L is irradiated onto joint portion 532T, thereby improving the weldability between joint portion 532T of current collector 53F and positive current collecting part 420 including rib 700. At this time, current collector 53F located outside (around) rib 700 is pressed down with jig 800, thereby further improving the weldability.

[0181] The present invention is not limited to the current collector 53F, but can be applied to similar welding points of the current collectors shown in the above-described embodiments.

[0182] (Embodiment 14) Next, with reference to FIGS. 36 to 40, a modified example in which a portion of a metal plate laminate that has been ultrasonically bonded in advance is laser-welded to another conductive member will be described.

[0183] 36, a plurality of recesses 910 and recesses 920 are provided as ultrasonic bonding marks (anvil marks and horn marks) on the front and back surfaces of joint portion 532T of current collector 53F. Laser welding may be performed on the ultrasonic bonding marks.

[0184] As shown in Figure 37, when observing the recess 910 of one ultrasonic bonding mark in a planar view, the recess 910 can be irradiated with a laser beam L. In this case, by making the recess 910 circular and the laser beam L also circular, stress concentration areas are not generated in response to forces in any direction on the plane other than the direction of peeling the bonded portion (arrow F in the figure), and tearing of the metal plate can be suppressed. Note that the recesses 910 and 920 of the upper and lower ultrasonic bonding marks should not be positioned opposite each other, but should be offset so that there is no gap when viewed in a planar view. This can suppress poor bonding and tearing of the metal plate (foil tearing), which are likely to occur when there is a gap.

[0185] 38, the ultrasonic bonding processability can be improved by reducing the size of the ultrasonic bonding mark recesses 910. Furthermore, by arranging a plurality of circular ultrasonic bonding mark recesses 910 in a circular arrangement and arranging a plurality of recesses 910 within the circular arrangement, stress concentration areas are not generated, and breakage of the metal plate can be suppressed.

[0186] As shown in FIG. 39, it is expected that the occurrence of stress concentration portions can be suppressed simply by changing the circular arrangement of the recesses 910 of the ultrasonic bonding marks to a circular shape.

[0187] As shown in FIG. 40, the recesses 910 of the ultrasonic bonding marks may be rectangular and arranged offset on the upper and lower surfaces of the bonding portion 532T, and a laser beam L may be scanned along the recesses 910 lined up on the upper surface to perform linear welding.

[0188] (Embodiment 15) Next, with reference to FIG. 41, the ultrasonic bonding portion between the first region of the current collector and the positive electrode tab group will be described.

[0189] In the joint 532R, the ultrasonic vibration direction is preferably in the protruding direction of the positive electrode tab groups 250, 280 (the direction of arrow D1 in the figure). By vibrating in the D1 direction, stress concentration at the base of the tab is less likely to occur when the tab stretches during bonding, and tab breakage can be suppressed. As a result, the bonding quality of the secondary battery can be stabilized.

[0190] When ultrasonically bonding a region where metal plates have been previously bonded to each other with a positive electrode tab group, the metal plates are preferably bonded together by diffusion bonding. It is preferable that the surface of the metal plate stack that contacts the positive electrode tab group is smooth. Since the metal plates are bonded together and one metal plate stack (approximately a single metal plate) can be ultrasonically bonded to the tab group, stable bonding is possible.

[0191] When ultrasonically bonding an area where metal plates have not previously been bonded to a group of tabs, both outer surfaces are flat, so that the metal plate and the group of tabs can be abutted in a favorable state, which is preferable because it allows for stable bonding.

[0192] (Embodiment 16) Next, with reference to FIGS. 42 to 44, the orientation of each surface of the first region of the current collector when the positive electrode tab group is ultrasonically bonded to a pre-ultrasonic bonded bonding region in the first region will be described.

[0193] The sizes (area in a plan view) of recesses 910, 920 formed in horn surface 532a and anvil surface 532b can be freely set. The smaller the sizes of recesses 910, 920, the more stable the fixation of first region 532A can be.

[0194] In FIG. 43, recess 910 is larger in size than recess 920, and horn surface 532a on which recess 910 is formed is disposed so as to abut against first region 532A of current collector 53E.

[0195] In FIG. 44, the size of recess 910 is larger than the size of recess 920, and anvil surface 532b on which recess 920 is formed is disposed so as to abut against first region 532A of current collector 53E.

[0196] The bonding may be performed by either the method shown in Fig. 43 or the method shown in Fig. 44. Preferably, as shown in Fig. 44, ultrasonic bonding is performed in a state in which the surface of positive electrode tab group 250, 280 on the side where the formed recesses are smaller (for example, anvil surface 532b) is positioned so as to abut against first region 532A of current collector 53E.

[0197] Furthermore, when the recesses 920 are small in size and numerous, joining the anvil surface 532b to the positive electrode tab groups 250, 280 generates local stress during joining, making joining easier (it is expected that workability will improve and joining strength will increase).

[0198] (Embodiment 17) 45 to 47, a case will be described in which positive electrode tab groups 250, 280 are joined to a first region of a current collector that is not ultrasonically joined, and positive electrode current collecting portion 420 is joined to a second region. For example, current collector 53D described in the sixth embodiment can be cited as one example.

[0199] As shown in FIG. 45, the first region 532A includes a bonding region R1 between the stacked metal plates and a bonding region R2 intended to be bonded to the positive electrode tab groups 250, 280, and the second region 532B includes a bonding region R3 intended to be bonded to the positive electrode current collecting portion 420.

[0200] In the joining region R1 between the laminated metal plates, similar to the cross section shown in FIG. 42, ultrasonic pressure welding marks are formed with a horn surface 532a on the illustrated surface and an anvil surface 532b on the opposite surface.

[0201] As shown in FIG. 46, in the bonding region R2 to which the positive electrode tab groups 250, 280 are bonded, ultrasonic bonding marks are formed by clamping between the horn H1 and the anvil A1.

[0202] 47, in the second region 532B, it is preferable to press (in the direction of arrow F1 in the figure) with a jig 800 the area where the metal plates are not joined together (the area where there are no press marks from the anvil A1 and horn H1) and weld with a laser L. In the area irradiated with the laser L, it is preferable to press with the jig 800 so that no gaps are generated between the metal plates.

[0203] Preferably, the metal plates are joined together by a method such as diffusion bonding that does not create irregularities on the surface of the laminate of metal plates, and the joined portions are most preferably laser welded.

[0204] Although the above embodiment has been described taking the positive electrode side as an example, the same configuration can also be applied to the negative electrode side.

[0205] 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]

[0206] 1 secondary battery, 53, 53A, 53B, 53C, 53D, 53E, 53F, 53G, 53H, 53I, 53J, 53K, 400, 410, 430, 431, 432, 440 current collector, 100 case, 110 case body, 111 first side portion, 112, 112A, 112B second side portion, 113, 114 opening, 115, 410A, 431A, 440A, 532R, 532S, 532T, 532U joint portion, 120, 130 sealing plate, 134 liquid hole, 150 gas exhaust valve, 200 electrode body, 200R positive electrode joint area, 201 first electrode body, 202 second electrode body, 210 negative electrode, 211 Negative electrode core, 212 Negative electrode active material layer, 220, 270 Negative electrode tab group, 221, 271 Curved portion, 230 Negative electrode tab, 240 Positive electrode, 241 Positive electrode core, 242 Positive electrode active material layer, 243 Positive electrode protective layer, 250, 280 Positive electrode tab group, 260 Positive electrode tab, 300 Electrode terminal, 301 Negative electrode terminal, 302 Positive electrode terminal, 303, 304 Plate-shaped member, 400A Negative electrode current collector, 400B Positive electrode current collector, 420 Positive electrode current collector, 420A, R1, R2, R3 Bonding region, 430A, 532A First region, 430B, 532B Second region, 430C Connection portion, 430D Hole portion, 510, 520, 530, 540 Insulating member, 532C first fuse portion, 532D second fuse portion, 532E first hole portion, 532a horn surface, 532b anvil surface, 700 rib, 800 jig.

Claims

1. an electrode body including a first electrode and a second electrode having a polarity different from that of the first electrode; a case for accommodating the electrode assembly; a first tab group in which a plurality of first electrode tabs electrically connected to the first electrodes are stacked; a first current collector connected to the first group of tabs; Equipped with the first current collector is a first laminate in which a plurality of metal plates are laminated, the first current collector includes a first region and a second region; the first tab group is joined to the first region; Another conductive member is joined to the second region. A method for manufacturing a secondary battery, a preparation step of preparing the first current collector having a joint portion where the metal plates are partially joined together; a first tab group connecting step of joining the first tab group to the first region; another conductive member connecting step of joining the other conductive member to the second region; A method for manufacturing a secondary battery comprising:

2. After the first tab group connecting step and the other conductive member connecting step, bending the first current collector between the first region and the second region; The method for manufacturing the secondary battery according to claim 1 .

3. a step of irradiating a high-energy ray to the joint portion of the first current collector where the metal plates are joined together, thereby joining the first current collector and the other conductive member; The method for manufacturing the secondary battery according to claim 1 .

4. the other conductive member has a protrusion, a step of irradiating the first current collector disposed on the protrusion with the high-energy ray to bond the first current collector and the protrusion; The method for manufacturing a secondary battery according to claim 3 .

5. a step of irradiating a region of the first current collector where the metal plates are not joined with high-energy rays to join the first current collector and the other conductive member; The method for manufacturing the secondary battery according to claim 1 .

6. a step of performing the process in a state in which the first current collector is pressed against the other conductive member by a jig around the area to be irradiated with the high-energy beam, The method for manufacturing a secondary battery according to claim 5 .

7. a step of bringing the first tab group into contact with the joint portion of the first current collector where the metal plates are joined to each other, thereby joining the first current collector and the first tab group; The method for manufacturing the secondary battery according to claim 1 .

8. a step of bringing the first tab group into contact with an area of ​​the first current collector where the metal plates are not joined to each other, thereby joining the first current collector and the first tab group; The method for manufacturing the secondary battery according to claim 1 .

9. an electrode body including a first electrode and a second electrode having a polarity different from that of the first electrode; a case for accommodating the electrode assembly; a first tab group in which a plurality of first electrode tabs electrically connected to the first electrodes are stacked; a first current collector connected to the first group of tabs; Equipped with the first current collector is a first laminate in which a plurality of metal plates are laminated, the first current collector includes a first region and a second region; the first tab group is joined to the first region; Another conductive member is joined to the second region, the first current collector has a region where the metal plates are joined to each other, other than a portion joined to the first tab group and a portion joined to the other conductive member; Secondary battery.

10. the first current collector has a first joint portion where the metal plates are joined together, a second joint portion is provided at which the first current collector and the other conductive member are laser-welded; When viewed along the lamination direction of the metal plates, The area of ​​the first joint is larger than the area of ​​the second joint. The secondary battery according to claim 9.

11. The second joint portion is provided within the first joint portion. The secondary battery according to claim 10.

12. the first current collector has a plurality of first recesses on a first outer surface, which is one of the outer surfaces; a joint portion between the first current collector and the other conductive member is formed linearly along the first recess; The secondary battery according to claim 9.

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