Secondary battery

Abstract

The invention relates to a secondary battery. In the secondary battery, the current collector is a first laminated body in which a plurality of metal plates are laminated, the current collector includes a first region and a second region, the positive electrode tab group is joined to the first region, the positive electrode current collector is joined to the second region, and the current collector includes a current collector bent portion bent between the first region and the second region. According to this secondary battery, the occurrence of damage in the tab group can be suppressed.

Description

TECHNICAL FIELD

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

[0002] In Japanese Patent Application Publication No. 2021-099936, regarding an invention of a power storage device, a configuration is disclosed in which a tab group connected to a current collector is bent. In Japanese Patent No. 5337586 and Japanese Patent No. 4120353, the use of a metal plate laminate for a current collector is disclosed. It is disclosed that a portion of the metal plate laminate that is to be ultrasonically joined in advance is laser-welded to another conductive member.

[0003] In order to be a configuration in which a tab group is bent, it is necessary to increase the length of the tab group. In the case where the length of the tab group is long, in a manufacturing process of a secondary battery or the like, it is possible that an unexpected breakage, bending, or the like occurs in the tab group and the tab group is damaged. SUMMARY

[0004] An object of the present technology is to provide a secondary battery that has a configuration capable of suppressing the occurrence of damage in a tab group.

[0005] The present technology provides the following secondary battery.

[0006] [1] A secondary battery characterized by comprising: an electrode body including a first electrode and a second electrode having a polarity different from that of the first electrode; a case that houses the electrode body; a first tab group in which a plurality of first electrode tabs electrically connected to the first electrode are laminated; and a first current collector connected to the first tab group, the first current collector being a first laminate in which a plurality of metal plates are laminated, the first current collector including a first region in which the first tab group is joined and a second region in which another conductive member is joined, the first current collector including a current collector bent portion that is bent between the first region and the second region.

[0007] [2] The secondary battery according to [1], characterized in that, in the current collector bent portion, the length of the metal plate located on the outermost side is longer than the length of at least one or more metal plates disposed on the inner side thereof.

[0008] [3] The secondary battery according to [1] or [2], characterized in that, in the first laminate, at a first end portion opposite to the first tab group, an end portion of the metal plate has a wall thickness portion having a thickness greater than that of the inner side thereof.

[0009] [4] The secondary battery according to any one of [1] to [3], characterized in that, in the first laminate, at a first end portion opposite to the first tab group, an end portion of the metal plate has a stepped portion.

[0010] [5] The secondary battery according to [4], characterized in that, in the first stack, the metal plate closest to the first tab group protrudes more than the other metal plates.

[0011] [6] The secondary battery according to any one of [1] to [5], characterized in that, in the first stack, at the first end portion opposite to the first tab group, the end portion of the metal plate is bent in a direction away from the tab group.

[0012] [7] The secondary battery according to any one of [1] to [6], characterized in that the first tab group has a tab group bent portion bent in a direction opposite to the bending direction of the first stack.

[0013] [8] The secondary battery according to any one of [1] to [7], characterized in that, at the end portion of the first end side of the second region of the first stack, the end portion of the metal plate abutting against the other conductive member protrudes more toward the first end side than the end portion of the other metal plates.

[0014] [9] The secondary battery according to any one of [1] to [8], characterized in that, at the end portion of the first end side of the second region of the first stack, the end portion of each of the metal plates gradually protrudes from the metal plate farthest from the other conductive member to the metal plate abutting against the other conductive member.

[0015] The above and other objects, features, aspects and advantages of the present application will become more apparent from the following detailed description of the present application taken in conjunction with the accompanying drawings, in which: BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is a front view showing the configuration of the secondary battery of Embodiment 1.

[0017] Figure 2 is a view showing the state of the secondary battery shown in Figure 1 from the direction of arrow II.

[0018] Figure 3 is a view showing the state of the secondary battery shown in Figure 1 from the direction of arrow III.

[0019] Figure 4 is a view showing the state of the secondary battery shown in Figure 1 from the direction of arrow IV.

[0020] Figure 5 is a view showing the state of the secondary battery shown in Figure 1 from the direction of arrow V.

[0021] Figure 6 is a front cross-sectional view of a secondary battery. Figure 1

[0022] Figure 7 is a cross-sectional view of a negative electrode (VII-VII cross-sectional view in FIG. 7). Figure 8

[0023] Figure 8 is a front view showing a negative electrode.

[0024] Figure 9 is a cross-sectional view of a positive electrode (IX-IX cross-sectional view in FIG. 9). Figure 10

[0025] is a front view showing a positive electrode. Figure 10

[0026] Figure 11 is a view showing the configuration of the periphery of a negative electrode current collector.

[0027] Figure 12 is a view showing the configuration of the periphery of a positive electrode current collector.

[0028] Figure 13 is a flowchart showing a manufacturing method of a secondary battery.

[0029] Figure 14 is a view showing a state in which a current collector is joined to a first electrode body and a second electrode body.

[0030] Figure 15 is a view showing a state in which a sealing plate is assembled to the current collector on the negative electrode side.

[0031] Figure 16 is a view showing a state in which the first electrode body and the second electrode body are overlapped.

[0032] Figure 17 is a view showing a process of inserting the first electrode body and the second electrode body into a case main body.

[0033] Figure 18 is a view showing a state in which a sealing plate is assembled to the current collector on the positive electrode side.

[0034] Figure 19 is a view showing a state in which an opening of the case main body is sealed.

[0035] Figure 20 is a view showing a metal plate constituting a current collector.

[0036] Figure 21 is a plan view of a current collector (first current collector) of Embodiment 2.

[0037] ​​​Figure 22 is a side view of the current collector representing the state before joining of Embodiment 2.

[0038] Figure 23 is a side view of the current collector representing the state after joining of Embodiment 2.

[0039] Figure 24 is a view representing the manufacturing method of the current collector using a metal sheet of Embodiment 3.

[0040] Figure 25 is a side view representing the 1st lamination state of the single layer metal sheet punched into a prescribed shape of Embodiment 3.

[0041] Figure 26 is a side view representing the 2nd lamination state of the single layer metal sheet punched into a prescribed shape of Embodiment 3.

[0042] Figure 27 is a side view representing the 3rd lamination state of the single layer metal sheet punched into a prescribed shape of Embodiment 3.

[0043] Figure 28 is a view representing the configuration in the case where the current collector of Embodiment 4 is joined to the positive electrode tab group and the positive electrode current collecting portion.

[0044] Figure 29 is a 1st view representing the joining configuration of the current collector of Embodiment 4 to the positive electrode tab group.

[0045] Figure 30 is a 2nd view representing the joining configuration of the current collector of Embodiment 4 to the positive electrode tab group.

[0046] Figure 31 is a 1st view representing the joining configuration of the current collector of Embodiment 4 to the positive electrode current collecting portion.

[0047] Figure 32 is a 2nd view representing the joining configuration of the current collector of Embodiment 4 to the positive electrode current collecting portion.

[0048] Figure 33 is a 3rd view representing the joining configuration of the current collector of Embodiment 4 to the positive electrode current collecting portion.

[0049] Figure 34 is a 4th view representing the joining configuration of the current collector of Embodiment 4 to the positive electrode current collecting portion.

[0050] Figure 35 is a view explaining the bending of the current collector of Embodiment 5.

[0051] Figure 36 is a view explaining the bending of the positive electrode tab group of Embodiment 5.

[0052] Figure 37 is a view showing a current collector in a case where single-layer metal sheets of which the collapse and burr have been generated are stacked, according to Embodiment 6.

[0053] Figure 38 is a view showing a state where the current collector shown in Figure 37 is provided with a joint region.

[0054] Figure 39 is a first view showing a current collector in a case where single-layer metal sheets of which the collapse and burr have been removed are stacked, according to Embodiment 6.

[0055] Figure 40 is a second view showing a current collector in a case where single-layer metal sheets of which the collapse and burr have been removed are stacked, according to Embodiment 6. DETAILED DESCRIPTION

[0056] Hereinafter, an embodiment of the present technology will be described. In this embodiment, there are cases where the same reference signs are attached to the same or corresponding portions and the description thereof is not repeated.

[0057] In the embodiment described below, the range of the present technology is not necessarily limited to the number, the amount, and the like, unless otherwise specifically described. In addition, in the embodiment described below, each of the constituent elements is not necessarily essential for the present technology, unless otherwise specifically described. In addition, the present technology is not limited to a technology that necessarily functions to achieve all the functional effects mentioned in the present embodiment.

[0058] In the present specification, the description of "comprise", and "include", "have" is open. That is, it can include other constituents than the constituent, or can not include it.

[0059] When a term of geometry and a term indicating a positional / directional relationship, such as a term of "parallel", "orthogonal", "inclined by 45°", "coaxial", "along", and the like are used in the present specification, these terms allow a manufacturing error or a slight variation. In the present specification, when a term indicating a relative positional relationship, such as "upper side", "lower side", and the like is used, these terms are used as a term indicating a relative positional relationship in one state, and the relative positional relationship is reversed or rotated to an arbitrary angle according to the setting direction of each mechanism (for example, reversing the entire mechanism upside down, and the like).

[0060] In the present specification, "secondary battery" can include a nickel-hydrogen battery and a sodium-ion battery, in addition to a lithium-ion battery. In the present specification, "electrode" can collectively refer to a positive electrode and a negative electrode.

[0061] In the drawings, when the electrode body possessed by the secondary battery is a laminated electrode body, the long side direction of the laminated surface is taken as the X direction, and when the electrode body is a wound electrode body, the direction along the winding axis thereof is taken as the X direction. In addition, the short side direction of the electrode body as viewed from the X direction is taken as the Y direction, and the long side direction of the electrode body as viewed from the X direction is taken as the Z direction. In order to facilitate understanding of the invention, there are portions in the drawings in which the dimensions of the respective components are changed from the actual dimensions.

[0062] In the present specification, there are cases in which the X direction is referred to as the "width direction" of the secondary battery 1, the electrode body 200, and the case main body 110, the Z direction is referred to as the "height direction" of the secondary battery 1, the electrode body 200, and the case main body 110, and the Y direction is referred to as the "thickness direction" of the secondary battery 1, the electrode body 200, and the case main body 110.

[0063] (Embodiment 1: Overall configuration of battery)

[0064] Figure 1 is a front view of the secondary battery 1 according to Embodiment 1. Figures 2-5 are views showing the secondary battery 1 as viewed from the directions of arrows II, III, IV, and V, respectively. Figure 1 is a view showing the state of the secondary battery 1. Figure 6 is a front view of the secondary battery 1. Figure 1 is a front cross-sectional view of the secondary battery 1.

[0065] The secondary battery 1 can be mounted on 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), and the like. However, the use of the secondary battery 1 is not limited to vehicle-mounted use.

[0066] As shown in Figures 1-6 , the secondary battery 1 includes a case 100, an electrode body 200, an electrode terminal 300, and a current collector 400. The case 100 includes a case main body 110, a sealing plate 120, and a sealing plate 130.

[0067] When a battery pack including the secondary battery 1 is configured, a plurality of secondary batteries 1 are arranged in the thickness direction thereof. The arranged secondary batteries 1 can be constrained by a constraint member in the arrangement direction (Y direction) to become a battery module, or can be directly supported by the side surface of the case of the battery pack without using a constraint member.

[0068] The housing main body 110 is composed of a cylindrical member, preferably a square cylindrical member. Thus, a square secondary battery 1 can be obtained. The housing main body 110 is made of metal. Specifically, the housing main body 110 is composed of aluminum, an aluminum alloy, iron, or an iron alloy, or the like.

[0069] As shown in FIG. 1, a sealing plate 120 and a sealing plate 130 are provided at both ends of the housing main body 110, respectively. The housing main body 110 can be formed into a square cylindrical shape, for example, by butting the end edges of plate-shaped members subjected to bending processing against each other (at the joint portion 115 exemplified in FIG. 2) and joining them to each other (e.g., laser welding). The corner portions of the "square cylindrical shape" can also have a circular arc shape. In addition, the secondary battery in the present technology is not necessarily limited to a square secondary battery. Figure 1 Figure 2 Figure 2 In the present embodiment, the housing main body 110 is formed longer in the width direction (X direction) of the secondary battery 1 than in the thickness direction (Y direction) and the height direction (Z direction) of the secondary battery 1. The size (width) of the housing main body 110 in the X direction is preferably about 30 cm or more. Thus, a relatively large (high-capacity) secondary battery 1 can be configured. The size (height) of the housing main body 110 in the Z direction is preferably about 20 cm or less, more preferably about 15 cm or less, and further preferably about 10 cm or less. Thus, a secondary battery 1 having a relatively low height (low height) can be configured, and, for example, mountability to a vehicle is improved.

[0070] The housing 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 constitutes a part of the side surface of the housing 100. The pair of second side surface portions 112 constitutes a bottom surface portion and an upper surface portion of the housing 100. The pair of first side surface portions 111 and the pair of second side surface portions 112 are provided so as to intersect each other. The pair of first side surface portions 111 and the pair of second side surface portions 112 are connected at the respective end portions. The area of each of the pair of first side surface portions 111 is larger than the area of each of the pair of second side surface portions 112.

[0071] As shown in FIG. 1, a sealing plate 120 and a sealing plate 130 are provided at both ends of the housing main body 110, respectively. The housing main body 110 can be formed into a square cylindrical shape, for example, by butting the end edges of plate-shaped members subjected to bending processing against each other (at the joint portion 115 exemplified in FIG. 2) and joining them to each other (e.g., laser welding). The corner portions of the "square cylindrical shape" can also have a circular arc shape. In addition, the secondary battery in the present technology is not necessarily limited to a square secondary battery.

[0072] As shown in FIG. 1, a sealing plate 120 and a sealing plate 130 are provided at both ends of the housing main body 110, respectively. The housing main body 110 can be formed into a square cylindrical shape, for example, by butting the end edges of plate-shaped members subjected to bending processing against each other (at the joint portion 115 exemplified in FIG. 2) and joining them to each other (e.g., laser welding). The corner portions of the "square cylindrical shape" can also have a circular arc shape. In addition, the secondary battery in the present technology is not necessarily limited to a square secondary battery. Figure 5

[0073] ​​​The thickness of the plate-shaped component in the gas discharge valve 150 is thinner than the thickness of the plate-shaped components other than the gas discharge valve 150 in the housing body 110. As a result, when the pressure inside the housing 100 becomes above a predetermined value, the gas discharge valve 150 ruptures first than other parts in the housing body 110, thus discharging the gas inside the housing 100 to the outside.

[0074] like Figure 2 As shown, a joining portion 115 is formed on another second side surface portion 112B of a pair of second side surface portions 112. The joining portion 115 extends along the width direction (X direction) of the secondary battery 1. In the joining portion 115, the end edges of the plate-shaped members constituting the outer casing body 110 are joined together.

[0075] like Figure 3 As shown, an opening 113 (second opening) is provided at the end of the outer casing 110 on the -X side in the X direction. The opening 113 is sealed by a sealing plate 120 (second sealing plate). A joint 115 is formed in the opening 113 to seal the opening 113. The opening 113 and the sealing plate 120 have a generally rectangular shape with the short side in the Y direction and the long side in the Z direction. The generally rectangular shape includes a rectangular shape or a shape with rounded corners, etc., that is substantially rectangular.

[0076] A negative terminal 301 (second electrode terminal) is provided on the sealing plate 120. The position of the negative terminal 301 can be changed appropriately. The negative terminal 301 is exposed on the outside of the sealing plate 120.

[0077] like Figure 4 As shown, an opening 114 (first opening) is provided at the end of the outer casing 110 on the +X side in the X direction. The opening 114 is located at the end opposite to the opening 113, and the openings 113 and 114 are opposite to each other. The opening 114 is sealed by a sealing plate 130 (first sealing plate). A joint 115 is formed in the opening 114 to seal it. The opening 114 and the sealing plate 130 have a generally rectangular shape with the short side in the Y direction and the long side in the Z direction.

[0078] A positive terminal 302 (first electrode terminal) and a liquid injection hole 134 are provided on the sealing plate 130. The positions of the positive terminal 302 and the liquid injection hole 134 can be changed appropriately.

[0079] Sealing plates 120 and 130 are made of metal. Specifically, sealing plates 120 and 130 are made of aluminum, aluminum alloy, iron, or iron alloy.

[0080] The negative terminal 301 is electrically connected to the negative terminal of the electrode body 200. The negative terminal 301 is mounted on the sealing plate 120, i.e., the housing 100. The negative terminal 301 is made of a conductive material (more specifically, a metal), such as copper or a copper alloy. A portion or layer of aluminum or an aluminum alloy may also be provided on the outer surface of the negative terminal 301. The negative terminal 301 is connected to the plate-shaped component 303.

[0081] The plate-shaped member 303 is located on the outside of the sealing plate 120. The plate-shaped member 303 is configured along the sealing plate 120. The plate-shaped member 303 is conductive. The plate-shaped member 303 is configured to ensure the connection area of ​​the busbar, etc., which electrically connects the secondary battery 1 and other adjacent secondary batteries. The connection between the negative terminal 301 and the plate-shaped member 303 can be formed, for example, by laser welding.

[0082] The positive terminal 302 is electrically connected to the positive terminal of the electrode body 200. The positive terminal 302 is mounted on the sealing plate 130, i.e., the housing 100. The positive terminal 302 is made of a conductive material (more specifically, a metal), such as aluminum or an aluminum alloy. The positive terminal 302 is exposed on the outside of the sealing plate 130. The positive terminal 302 is connected to the plate-shaped component 304.

[0083] The plate-shaped member 304 is located on the outside of the sealing plate 130. The plate-shaped member 304 is configured along the sealing plate 130. The plate-shaped member 304 is conductive. The plate-shaped member 304 is configured to ensure the connection area of ​​the busbar, etc., which electrically connects the secondary battery 1 and other adjacent secondary batteries. The connection between the positive terminal 302 and the plate-shaped member 304 can be formed, for example, by laser welding.

[0084] The injection port 134 is sealed by a sealing component (not shown). Such sealing components can be, for example, blind-hole rivets or other metal parts.

[0085] Electrode body 200 is a flat electrode body having a positive electrode and a negative electrode (described later) stacked on top of each other. Specifically, electrode body 200 is a stacked electrode body in which multiple positive electrodes and multiple negative electrodes are alternately stacked with a diaphragm (not shown). However, in this specification, "electrode body" is not limited to a stacked electrode body, and may also be a wound electrode body in which strip-shaped positive electrodes and strip-shaped negative electrodes are wound together with a strip-shaped diaphragm. The diaphragm may, for example, be made of a polyolefin microporous membrane. When the electrode body is a stacked electrode body including multiple positive electrodes and multiple negative electrodes, positive electrode tabs disposed on each positive electrode can be stacked to form a positive electrode tab group, and negative electrode tabs disposed on each negative electrode can be stacked to form a negative electrode tab group.

[0086] like Figure 6 As shown, the outer casing 100 houses the electrode body 200.Figure 6 In the following section, the first electrode 201, which will be described later, will be illustrated. The first electrode 201 is housed within the outer casing 100 with its long side parallel to the X direction.

[0087] Specifically, inside the insulating sheet (not shown) disposed within the housing 100, one or more stacked electrode bodies are housed together with an electrolyte (not shown). A solid electrolyte may also be used instead of the electrolyte.

[0088] The first electrode 201 includes a generally 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.

[0089] The negative electrode tab group 220 and the positive electrode tab group 250 are formed to protrude from the central part of the electrode body 200 toward the sealing plate 120 or the sealing plate 130, respectively.

[0090] The current collector 400 includes a negative current collector 400A and a positive current collector 400B. The electrode body 200 is electrically connected to the negative terminal 301 and the positive terminal 302 via the current collector 400.

[0091] The negative current collector 400A is electrically connected to the negative electrode tab assembly 220 and the negative terminal 301. The negative current collector 400A can be made of a conductive material (more specifically, a metal such as copper or a copper alloy).

[0092] The positive current collector 400B is electrically connected to the positive electrode tab assembly 250 and the positive terminal 302. The positive current collector 400B can be made of a conductive material (more specifically, a metal such as aluminum or an aluminum alloy).

[0093] (Composition of electrode body 200)

[0094] like Figure 7 and Figure 8 As shown, 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 coating a negative electrode active material layer slurry using a die coater.

[0095] A negative electrode tab 230, composed of a negative electrode core 211, is provided at one end of the negative electrode 210 in the width direction. When the negative electrodes 210 are stacked, multiple negative electrode tabs 230 are stacked to form a negative electrode tab group 220. The length of each negative electrode tab 230 in the protruding direction among the multiple negative electrodes 210 can be appropriately adjusted considering the connection state between the negative electrode tab group 220 and the negative current collector 400A. The shape of the negative electrode tab 230 is not limited to...Figure 8 The shape illustrated.

[0096] As Figure 9 and Figure 10 illustrated, the positive electrode 240 has a different polarity from 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 coating a positive electrode active material layer slurry with a die coater.

[0097] A positive electrode tab 260 composed of the positive electrode core 241 is provided at one end portion in the width direction of the positive electrode 240. When the positive electrode 240 is laminated, a plurality of positive electrode tabs 260 are laminated to become a positive electrode tab group 250. The length of the protruding direction of each of the positive electrode tabs 260 in the plurality of positive electrodes 240 can be appropriately adjusted in consideration of 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 Figure 10 The shape illustrated.

[0098] The positive electrode protective layer 243 is provided at the root portion of the positive electrode tab 260. However, the positive electrode protective layer 243 does not necessarily have to be provided.

[0099] In a typical example, the thickness of the negative electrode tab 230 (1 piece) is smaller than the thickness of the positive electrode tab 260 (1 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.

[0100] (Connection structure of the electrode body 200 and the current collector 400)

[0101] As Figure 11 , Figure 12 illustrated, the electrode body 200 includes a first electrode body 201 and a second electrode body 202. The first electrode body 201 and the second electrode body 202 each include the positive electrode 240 and the negative electrode 210. The electrode body 200 can also be composed of three or more electrode bodies.

[0102] The electrode body 200 is formed by overlapping the first electrode body 201 and the second electrode body 202. The first electrode body 201 and the second electrode body 202 are arranged in the thickness direction (Y direction) of the first electrode body 201 and the second electrode body 202.

[0103] The first electrode body 201 includes: the positive electrode tab group 250 (first electrode tab), which is disposed at the end portion (Y1) of one side of the first electrode body 201 and is electrically connected to the positive electrode 240; and the negative electrode tab group 220 (second electrode tab), which is disposed at the end portion (Y2) of the other side of the first electrode body 201 and is electrically connected to the negative electrode 210. Figure 12 Figure 11 The second electrode body 202 includes: the positive electrode tab group 250 (third electrode tab), which is disposed at the end portion (Y3) of one side of the second electrode body 202 and is electrically connected to the positive electrode 240; and the negative electrode tab group 220 (fourth electrode tab), which is disposed at the end portion (Y4) of the other side of the second electrode body 202 and is electrically connected to the negative electrode 210.​

[0104] The second electrode body 202 includes a positive tab group 280 (third electrode tab) disposed at an end portion of one side of the second electrode body 202 and electrically connected to the positive electrode 240, and a negative tab group 270 (fourth electrode tab) disposed at an end portion of the other side of the second electrode body 202 and electrically connected to the negative electrode 210. Figure 12 Figure 11

[0105] As shown in FIG. 2B (configuration of the negative electrode side), the negative tab group 220 and the negative tab group 270 are electrically connected to the current collector 410 (negative electrode current collector 400A). The current collector 410 (second current collector) to which the negative tab group 220 and the negative tab group 270 are joined can be composed of a plate-shaped member made of metal. In addition, the current collector 410 can be composed of a single member. Figure 11

[0106] The negative tab group 220 has a bent portion 221. The bent portion 221 is a portion in which the negative tab group 220 is bent. The negative tab group 270 has a bent portion 271. The bent portion 271 is a portion in which the negative tab group 270 is bent.

[0107] The negative tab group 220 and the negative tab group 270 are bent in opposite directions with their front end portions approaching each other, respectively.

[0108] In addition, in the embodiment, the front end portions of the negative tab group 220 and the negative tab group 270 are separated from each other, but the present technology is not limited to this configuration, and the front end portions of the negative tab group 220 and the negative tab group 270 can also be in contact with each other.

[0109] The current collector 410 electrically connects the negative terminal 301 to the negative tab group 220 and the negative tab group 270. The current collector 410 has a long side direction in the Z direction and a short side direction in the Y direction.

[0110] The negative tab group 220 and the negative tab group 270 are joined to the current collector 410 at a joining portion 410A (see FIG. 2B) described later, respectively. The joining portion 410A can be formed, for example, by ultrasonic joining, resistance welding, laser welding, caulking, or the like. Figure 14 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 terminal 301 can also be electrically connected to the sealing plate 120, and the sealing plate 120 can also function as the negative terminal 301.

[0111]

[0112] ​​​​A separator (not shown) can also be provided between the sealing plate 120 and the main body portion of the electrode body 200 (excluding the negative electrode tab groups 220, 270). The separator can be composed of a resin member having insulating properties. The negative electrode tab groups 220, 270 are protected by passing inside the separator.

[0113] As shown in Figure 12 , the positive electrode tab group 250 and the positive electrode tab group 280 are electrically connected to the current collector 430 (positive electrode current collector 400B), respectively. More specifically, the positive electrode tab group 250 is joined to the current collector 431, and the positive electrode tab group 280 is joined to the current collector 432.

[0114] The lengths of the positive electrode tab groups 250, 280 can be appropriately changed. It is preferable that the lengths of the positive electrode tab groups 250, 280 are the same as each other, but they can be different from each other. There are cases where the lengths of the positive electrode tab groups 250, 280 are shorter than those of the negative electrode tab groups 220, 270, and cases where they are longer than those of the negative electrode tab groups 220, 270.

[0115] The current collector 431 (first current collector) for joining the positive electrode tab group 250 is composed of a laminate (first laminate) in which a plurality of metal plates 4300 (refer to Figure 20 ) are laminated. Similarly, the current collector 432 (third current collector) for joining the positive electrode tab group 280 is composed of a laminate (second laminate) in which a plurality of metal plates 4300 (refer to Figure 20 ) are laminated. In the current collectors 431, 432, the number of the laminated metal plates 4300 is two or more, and is preferably three or more, and more preferably five or more, for example. In addition, it can be 20 or less, and is preferably 15 or less, and more preferably 10 or less, for example. Further, the same can apply when a current collector in which metal plates are laminated is used on the negative electrode side.

[0116] The current collectors 431, 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, 432 are joined to the positive electrode current collecting portion 420 in a state of being bent, and are electrically connected to the positive electrode terminal 302.

[0117] The current collector 430 is composed of two current collectors 431, 432, and a more stable current collecting structure can be constituted. 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 can 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 (the number of times can be reduced).

[0118] In the example of Figure 12 , the portions where the current collectors 431, 432 overlap each other (the portions indicated by the arrows in FIG. 7) are joined to the positive electrode current collecting portion 420.Figure 18 The current collectors 431 and 432 are joined to the positive current collector 420 in the bonding region 420A. However, the scope of this technology is not limited to this, and the current collectors 431 and 432 can also be joined to the positive current collector 420 at positions that are separated or adjacent to each other in the positive current collector 420.

[0119] Positive electrode tab group 250 and positive electrode tab group 280 are respectively located in the positive electrode junction region 200R (see below) Figure 14 It is joined with current collectors 431 and 432. The positive electrode joining region 200R can be formed, for example, by ultrasonic joining, resistance welding, laser welding, seam sealing, etc.

[0120] The positive junction region 200R of the current collector 431 and the positive electrode tab group 250, and the positive electrode junction region 200R of the current collector 432 and the positive electrode tab group 280 are formed at positions that are separated from each other in the XY plane.

[0121] like Figure 12 As shown, in the X direction, a positive electrode tab assembly 250 is disposed 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 current collectors 431 and 432). A positive electrode tab assembly 280 can be disposed in the gap between current collectors 431 and 432, or both positive electrode tab assemblies 250 and 280 can be disposed in the gap between current collectors 431 and 432. Therefore, the gap between current collectors 431 and 432 can be effectively utilized.

[0122] An insulating component 520 is disposed between the plate-shaped component 304 and the sealing plate 130. An insulating component 540 is disposed between the positive terminal 302 and the sealing plate 130. However, the positive terminal 302 can also be electrically connected to the sealing plate 130, and the sealing plate 130 can also function as the positive terminal 302.

[0123] Alternatively, a spacer (not shown) may be disposed between the sealing plate 130 and the main body of the electrode body 200 (excluding the positive electrode tabs 250 and 280). The spacer may be made of an insulating resin component. The positive electrode tabs 250 and 280 are protected by passing through the spacer.

[0124] (Manufacturing process of secondary battery 1)

[0125] The manufacturing method of the secondary battery according to this embodiment will be described below. Figure 13 This is a flowchart illustrating the manufacturing method of secondary battery 1.

[0126] like Figure 13As shown, the method of manufacturing the secondary battery 1 includes a process of producing the first electrode body 201 and the second electrode body 202 (S1), a process of joining the negative tab group 220 and the negative tab group 270 to the current collector 410 (S2), a process of joining the positive tab group 250 to the current collector 431 (S3), a process of joining the positive tab group 280 to the current collector 432 (S4), a process of electrically connecting the current collector 410 to which the negative tab group 220 and the negative tab group 270 are joined to the negative terminal 301 (S5), a process of overlapping the first electrode body 201 and the second electrode body 202 (S6), a process of assembling the separator and the insulating sheet to the electrode body 200 (S7), a process of inserting the first electrode body 201 and the second electrode body 202 into the case main body 110 (S8), a process of electrically connecting the current collectors 431 and 432 to which the positive tab groups 250 and 280 are joined to the positive terminal 302 (S9), a process of joining the sealing plates 120 and 130 to the case main body 110 to seal the openings 113 and 114 (S10), and a process of performing a leak test (S11).

[0127] Figures 14-19 is a view showing each process in the method of manufacturing the secondary battery 1.

[0128] In the process of producing the first electrode body 201 and the second electrode body 202 (S1), it is preferable that the negative tab group 220, the positive tab group 250, the negative tab group 270, and the positive tab group 280 are each cut by a portion of the leading end so that the length of the leading end becomes the same length at the time of bundling.

[0129] As shown in Figure 14 After the first electrode body 201 and the second electrode body 202 are produced, the negative tab groups 220 and 270 are joined to the current collector 410 (S2), the positive tab group 250 is joined to the current collector 431 (S3), and the positive tab group 280 is joined to the current collector 432 (S4).

[0130] The negative tab groups 220 and 270 are joined to the current collector 410 at the joining portion 410A. The positive tab group 250 is joined to the current collector 431 at the positive joining region 200R. The positive tab group 280 is joined to the current collector 432 at the positive joining region 200R.

[0131] 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 arrow DR1 direction.

[0132] In Figure 14In this example, in the height direction of the first electrode 201 and the second electrode 202, the current collector 410 and current collectors 431 and 432 are configured to be offset to one side from the center of the first electrode 201 and the second electrode 202. Furthermore, in the height direction of the first electrode 201 and the second electrode 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 respectively configured to be offset to one side from the center of the first electrode 201 and the second electrode 202.

[0133] However, the scope of this technology is not limited thereto. Current collectors 410 and 431, 432 may also be disposed at the center of the first electrode 201 and the second electrode 202 in the height direction of the first electrode 201 and the second electrode 202. In addition, in the height direction of the first electrode 201 and the second electrode 202, negative electrode tab group 220, positive electrode tab group 250, negative electrode tab group 270 and positive electrode tab group 280 may also be disposed at the center of the first electrode 201 and the second electrode 202, respectively.

[0134] like Figure 15 As shown, the current collector 410, which is connected to the negative electrode tab group 220 and the negative electrode tab group 270, is assembled onto the sealing plate 120. A current collector 440 and a negative terminal 301 are pre-installed on the sealing plate 120. The current collector 410 is assembled onto the sealing plate 120 via the current collector 440. The current collector 410 is connected to the current collector 440 at a joint 440A. The joint 440A can be formed, for example, by laser welding. The result is that the current collector 410 is electrically connected to the negative terminal 301 (S5).

[0135] like Figure 16 As shown, in the thickness direction of the first electrode body 201 and the second electrode body 202 (with... Figure 14 and Figure 15 The negative electrode tab group 220 and the negative electrode tab group 270 are bent in a direction orthogonal to the DR1 direction so that the first electrode body 201 overlaps with the second electrode body 202 (S6). Here, the negative electrode tab group 220 and the negative electrode tab group 270 are bent in such a way that their front ends face each other.

[0136] When the first electrode 201 and the second electrode 202 are "overlapped", the first electrode 201 and the second electrode 202 can overlap directly, or other components can be arranged between the first electrode 201 and the second electrode 202. In addition, the first electrode 201 and the second electrode 202 can be fixed by tape or the like, or they can be left unfixed.

[0137] The separator and the insulating sheet (S7) described above are assembled to the electrode body 200. However, in the present technology, the separator and the insulating sheet are not necessarily essential components. The insulating sheet does not necessarily need to cover the entire surface of the electrode body 200. In the case where the electrode body 200 is covered with the insulating sheet, it is preferable that the separator is also covered with the insulating sheet.

[0138] As shown in Figure 17 , the first electrode body 201 and the second electrode body 202 that overlap each other are inserted into the case main body 110 with the current collector 430 side as the front end (S8).

[0139] At the time of insertion of the electrode body 200 into the case main body 110, the electrode body 200 can be pulled from the positive electrode side, or the electrode body 200 can be pressed from the negative electrode side. In the case where the electrode body 200 is pressed 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.

[0140] As shown in Figure 18 , after the electrode body 200 is inserted into the case main body 110, the current collector 430 that is joined to the positive electrode tab group 250 and the positive electrode tab group 280 is assembled to the sealing plate 130. The positive electrode current collecting portion 420 and the positive electrode terminal 302 are pre-installed to the sealing plate 130. The current collector 430 is assembled to the sealing plate 130 via the positive electrode current collecting portion 420. The current collector 410 is joined to the positive electrode current collecting portion 420 at the joining region 420A. The joining region 420A can be formed, for example, by laser welding or the like. As a result of the above, the current collector 430 is electrically connected to the positive electrode terminal 302 (S9).

[0141] After the current collector 431, 432 that is joined to the positive electrode tab group 250, 280 and the positive electrode terminal 302 are electrically connected, the current collector 431, 432 is bent together with the positive electrode tab group 250, 280 into the shape shown in Figure 12 . It is preferable that the current collector 431, 432 is bent at the same time, but the current collector 431, 432 can be bent sequentially.

[0142] As shown in Figure 19 , the sealing plates 120, 130 are joined to the case main body 110 (S10). The sealing plate 120 seals the opening 113 of the case main body 110, and the sealing plate 130 seals the opening 114 of the case main body 110. Thereby, the first electrode body 201 and the second electrode body 202 are housed in the case 100.

[0143] After the above-described procedures, a leak check and other inspections are performed (S11). After the leak check, the secondary battery 1 is dried to remove moisture from the casing 100. Then, electrolyte is injected into the interior of the casing 100 through the injection hole 134. During electrolyte injection, the casing 100 is tilted with the sealing plate 130 on top and the sealing plate 120 on the bottom, and electrolyte is injected into the interior of the casing 100 through the injection hole 134 of the sealing plate 130. Then, vacuum charging is performed. During vacuum charging, the injection hole 134 may be temporarily sealed. Then, the injection hole 134 is sealed, and the secondary battery 1 is completed.

[0144] The order of the insertion process of electrode 200 and the connection process of current collector is not limited to the example above. For example, the order of the joining process (S2 to S4) of current collectors 410, 431, and 432 can be appropriately changed.

[0145] In this embodiment, an example is described in which the current collector 430 is electrically connected to the positive terminal 302 in a state where the first electrode 201 and the second electrode 202 are completely disposed within the housing body 110 after the process of inserting the first electrode 201 and the second electrode 202 into the housing body 100 (S8) is completed (S9). However, it is also possible to electrically connect the positive terminal 302 to the electrode 200 before the insertion process (S8) of the electrode 200 into the housing body 110 is completely completed (midway through the insertion process) (S9).

[0146] In this embodiment, an example of bending the current collectors 431 and 432 after the step (S9) of electrically connecting the current collectors 431 and 432 to the positive terminal 302 is described. However, it is also possible to deform the current collectors 431 and 432 before the step (S9) of electrically connecting the current collectors 431 and 432 to the positive terminal 302.

[0147] (Composition of metal plate 4300)

[0148] like Figure 20 As shown, the metal plate 4300 includes a first region 430A that is engaged with the positive electrode tabs 250 and 280, a second region 430B that is engaged with the positive electrode current collector 420, and a connecting portion 430C, a hole 430D, and a cutout 430E disposed between the first region 430A and the second region 430B.

[0149] In forming the current collector 430, the plurality of metal plates 4300 can be joined to each other in the first region 430A and the second region 430B (first portion). The joining of the plurality of metal plates 4300 to each other is preferably performed, for example, by ultrasonic joining, diffusion joining, or the like. In the case of diffusion joining, the plurality of metal plates 4300 are preferably joined to each other by applying pressure to the stacked metal plates 4300 in a state where the stacked metal plates 4300 are heated at a temperature lower than the melting point of the metal plates 4300. The joining of the plurality of metal plates 4300 to each other is performed before the other conductive members (the positive electrode tab groups 250, 280, and the positive electrode current collector 420) are joined to the first region 430A and the second region 430B.

[0150] The connection portion 430C (second portion) of the current collector 430 preferably includes a region in which the plurality of metal plates 4300 are not joined to each other. Thus, the current collector 430 is easily bent at the connection portion 430C. The portion of the metal plates 4300 that is bent preferably includes a region in which the plurality of metal plates 4300 are not joined to each other. In addition, the plurality of metal plates 4300 are preferably not joined to each other in the entirety of the portion of the metal plates 4300 that is bent. There can also be a portion in which the plurality of metal plates 4300 are not joined to each other in regions other than the connection portion 430C (the first region 430A and the second region 430B).

[0151] In the region in which the plurality of metal plates 4300 are not joined to each other, the metal plates 4300 can abut each other. In addition, there can be a slight gap between the metal plates 4300. In the region in which the plurality of metal plates 4300 are not joined to each other, the metal plates 4300 are not welded or the like to each other, and a clear boundary is present between the metal plates 4300. For example, there is a natural oxide film on the surface of each metal plate 4300.

[0152] By providing the hole portion 430D and the notch 430E in the connection portion 430C, the cross-sectional area of the connection portion 430C can be reduced, and the current collector 430 is easily bent at the connection portion 430C. In addition, the connection portion 430C can function as a fuse portion.

[0153] The metal sheet 4300 can be composed of, for example, aluminum or an aluminum alloy. In addition, the metal sheet 4300 can also be composed of copper, a copper alloy, nickel, a nickel alloy, iron, or an iron alloy. The thickness of one metal sheet 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 sheet 4300 is preferably, for example, 0.05 mm or more, and more preferably 0.08 mm or more. In addition, the thickness is preferably 0.5 mm or less, more preferably 0.3 mm or less, and further preferably 0.2 mm or less. In this case, the thickness of one metal sheet 4300 is preferably 1 / 2 or less, and more preferably 1 / 5 or less, the thickness of the positive electrode current collecting portion 420. In addition, on the negative electrode side, the same configuration can be used in the case where a current collector in which metal sheets are laminated is used.

[0154] The number of metal sheets 4300 that make up the current collector 431, 432 can be appropriately changed. The total thickness (first thickness: T1) of the current collector 431, 432 is preferably greater than the total thickness (second thickness: T2) of the positive electrode tab group 250, 280 that is joined to the current collector 431, 432. More preferably, T1 / T2 is about 1.5 or more, and further preferably T1 / T2 is about 2 or more.

[0155] In this case, the "total thickness of the current collector 431, 432" refers to the total thickness of the portions of the current collector 431, 432 that do not have irregularities. In addition, the "total thickness of the positive electrode tab group 250, 280" refers to the total thickness at portions of the positive electrode tab group 250, 280 that are collected, other than the positive electrode joining region 200R.

[0156] In the present embodiment, by using a current collector 430 composed of a laminate of a plurality of metal sheets 4300, a current collector 430 that suppresses an increase in resistance and easily stably deforms can be provided. As a result, the positive electrode current collector 400B can be miniaturized, and the energy density of the secondary battery 1 can be increased.

[0157] When the current collector 430 connected to the positive electrode tab group 250, 280 and the positive electrode terminal 302 are electrically connected in a state where the first electrode body 201 and the second electrode body 202 are disposed inside the case main body 110, and then the current collector 430 is bent, by the current collector 430 being composed of a laminate of a plurality of metal sheets 4300, a secondary battery 1 that has a high energy density and high reliability can be more stably and efficiently manufactured. In this case, with respect to the negative electrode tab group 220, 270, as shown in FIG. 17, a configuration in which one face of the current collector 410 is joined in a state where the negative electrode tab group 220, 270 is bent is particularly preferable. In addition, the positive electrode side and the negative electrode side can be reversed. Figure 11

[0158] ​Furthermore, in this embodiment, during the process (S2) of connecting the current collector 410 to the negative electrode tabs 220 and 270, as follows: Figure 14 As shown, the negative electrode tabs 220 and 270 are joined to the current collector 410 with the first electrode 201 positioned on one side and the second electrode 202 positioned on the other side. In this configuration, since the main bodies of the first electrode 201 and the second electrode 202 are relatively far from the current collector 410, there are multiple options for joining them, and the negative electrode tabs 220 and 270 can be made relatively short. By shortening the negative electrode tabs 220 and 270, the internal space of the casing 100 can be effectively utilized to further increase the energy density of the secondary battery 1.

[0159] Furthermore, in this embodiment, since the current collectors 431 and 432 are bent in the same direction while the first electrode 201 and the second electrode 202 are overlapping, the space on the inner periphery of the bent portion of the current collector 431 can be efficiently utilized to arrange the current collector 432. As a result, the positive electrode current collector 400B can be further miniaturized to increase the energy density of the secondary battery 1.

[0160] Furthermore, in this embodiment, by pre-attaching the current collectors 431 and 432 to the positive electrode tabs 250 and 280 (S3, S4), the positive electrode tabs 250 and 280 can be protected and their damage (deformation, breakage, etc.) can be suppressed during the subsequent overlapping process (S6) of the first electrode 201 and the second electrode 202, and the insertion process (S8) of the first electrode 201 and the second electrode 202 into the outer casing 110. As a result, a highly reliable secondary battery 1 can be provided.

[0161] (Replenish)

[0162] In this embodiment, such as Figure 12 As shown, the current collectors 431 and 432 can be bent in the same direction when the first electrode 201 and the second electrode 202 are overlapped, but the current collectors 431 and 432 can also be bent in opposite directions.

[0163] In this embodiment, for in Figure 12 The example shown illustrates an instance where the current collectors 431 and 432 are joined to the positive electrode tabs 250 and 280 from the same side (from the left side of the diagram for both positive electrode tabs 250 and 280). In this case, the state before the first electrode body 201 and the second electrode body 202 overlap is described. Figure 14 , Figure 15 Under these conditions, for the positive electrode tabs 250 and 280, the current collectors 431 and 432 are connected from different sides.

[0164] However, the scope of the present technology is not limited to the above, and Figure 12 In the state shown, the current collectors 431, 432 can also be joined to the positive tab group 250, 280 from mutually different sides. In this case, the current collectors 431, 432 are joined to the positive tab group 250, 280 from mutually different sides in a state in which the first electrode body 201 and the second electrode body 202 are overlapped (before the first electrode body 201 and the second electrode body 202 are overlapped). Figure 14 、 Figure 15 ) in which the first electrode body 201 and the second electrode body 202 are overlapped.

[0165] In the present embodiment, an example in which a bent current collector 430 composed of a metal plate laminate is used on the positive side (A side) and a current collector 410 composed of a single member made of metal is used on the negative side (B side) is described, but the scope of the present technology is not limited thereto, and a configuration opposite to the above can also be adopted on the positive side and the negative side. In addition, a current collector 410 in which a plurality of members are integrated can also be used instead of a single member. Figure 12 Figure 11 In the present embodiment, an example in which a bent current collector 430 composed of a metal plate laminate is used on the positive side (A side) and a current collector 410 composed of a single member made of metal is used on the negative side (B side) is described, but the scope of the present technology is not limited thereto, and a configuration opposite to the above can also be adopted on the positive side and the negative side. In addition, a current collector 410 in which a plurality of members are integrated can also be used instead of a single member.

[0166] (Embodiment 2: Configuration of current collector)

[0167] The configuration of the current collector 431, 432 used in the secondary battery described above will be described with reference to Figures 21-23 The current collector 431 (first current collector) is connected to the positive tab group 250, and the current collector 432 (second current collector) is connected to the positive tab group 280. Since the current collector 431 and the current collector 432 have the same configuration, the configuration of the current collector 431 will be described in the following description.

[0168] The current collector 431 has, for example, a plurality of metal plates 4300 (the number of sheets is omitted in the drawing) each having a thickness of about 0.1 mm laminated by 15 or so. The current collector 431 includes a first region 431A connected to the positive tab group 250 and a second region 431B connected to the positive current collecting portion 420 as another conductive member.

[0169] The width W1 of the first region 431A and the second region 431B is set to be the same.

[0170] In the current collector 431, between the first region 431A and the second region 431B, a first fuse portion 431C and a second fuse portion 431D are provided as connection portions that are fused when a current of a prescribed value or more flows. The width W2 of the first fuse portion 431C and the second fuse portion 431D is set to be smaller than the width W1 of the first region 431A and the second region 431B.

[0171] ​A first hole portion 431E is provided between the first fuse portion 431C and the second fuse portion 431D. A first notch 431F of a U shape which is recessed toward the inside is provided on both end sides of the first fuse portion 431C and the second fuse portion 431D. The shape of the first hole portion 431E is not limited to an elliptical shape, and can be a rectangular shape, a circular shape, or the like. The shape of the first notch 431F is not limited to a U shape.

[0172] (Embodiment 3: Method for manufacturing current collector 431)

[0173] Next, with reference to Figures 24-26 , a method for manufacturing the current collector 431 having the above-described configuration will be described.

[0174] As shown in Figure 24 , a cutting step of cutting a raw sheet of the long strip-shaped metal sheet 4300 into a prescribed shape CA of the current collector 431 at a plurality of prescribed positions is implemented. As a method of cutting, a method of using a die, a tool, or the like to punch, or cutting using irradiation of an energy ray such as a laser, or the like can be cited.

[0175] A plurality of single-layer metal sheets 431f cut into the prescribed shape CA are stacked, and the single-layer metal sheets 431f are joined to each other to form a joining region 431R of the stack.

[0176] In the cutting step, the outer peripheral portion including the first notch 431F and the first hole portion 431E can be cut at once. Alternatively, the portion of the first hole portion 431E can be cut after the outer peripheral portion including the first notch 431F is cut.

[0177] As shown in Figure 25 , it is preferable that the cutting in the cutting step be performed by irradiation of an energy ray such as a laser, and a wall thickness portion 431r having a thickness thicker than the inside be formed at the end portion (rim portion) of the cut single-layer metal sheet 431f. As the shape of the wall thickness portion 431r, it is preferable that the outer surface be curved with a degree of roundness.

[0178] As shown in Figure 25 , a plurality of single-layer metal sheets 431f can be stacked in a manner in which the respective wall thickness portions 431r overlap. In the configuration described below in Figure 26 and Figure 27 , a single-layer metal sheet 431f having a wall thickness portion 431r at the end portion can be used.

[0179] When the current collector 431 has the wall thickness portion 431r at the end portion, the strength of the end portion is improved, so in the step of stacking the single-layer metal sheets 431f, the single-layer metal sheets 431f become easy to handle, and the productivity is improved.

[0180] As shown in Figure 26As shown, single-layer metal plates 431f with the same shape are stacked with their ends offset by a distance S. Since the current collector 431 is imagined to be bent, the offset direction is from the first region towards the second region (the left-right direction shown in the diagram). By offsetting the ends of the single-layer metal plates 431f in this way, gaps between the single-layer metal plates 431f caused by burrs and cutting marks that sometimes occur at the ends of the current collector 431 can be reduced.

[0181] It can also be like Figure 27 As shown, single-layer metal plates 431f of different sizes are prepared and stacked in a manner that creates a stepped difference at the ends (distance S). The staggered direction is... Figure 26 The directions shown are the same. In this configuration, the gaps between the single-layer metal plates 431f caused by burrs and cutting marks that sometimes occur at the end of the current collector 431 can also be reduced.

[0182] (Implementation Method 4)

[0183] Next, refer to Figures 28-37 The structure of the current collector 431 having the above configuration is described in connection with the positive electrode tab group 250 and the positive electrode current collector 420 (other conductive parts).

[0184] In the following description, the current collector 431, which is the first current collector, will be described, but the connection of the current collector 432, which is the second current collector, to the positive electrode tab group 280 and the positive electrode current collector 420 is also the same.

[0185] (Joint structure of current collector 431 to positive current collector 420)

[0186] Reference Figures 28-30 The joining structure of the current collector 431 to the positive current collector 420 will be described. The diagram shown in the figure, enclosed by X, illustrates an example of the fixed state of the current collector 431 and the positive current collector 420. The joining region 431R provided in the second region 431B of the current collector 431 is fixed to the positive current collector 420 by laser welding L.

[0187] At this time, at the front end of the second region 431B of the current collector 431 surrounded by X1 (the end away from the first region 431A), the single-layer metal plate 431f that abuts against the positive current collector 420 can protrude towards the front end of the other single-layer metal plates 431f.

[0188] exist Figure 28 In the configuration shown, the following can be used Figure 26 or Figure 27The end portion of each single-layer metal plate 431f gradually protrudes toward the front end side from the single-layer metal plate 431f farthest from the positive electrode current collecting portion 420 to the single-layer metal plate 431f abutting against the positive electrode current collecting portion 420.

[0189] On the other hand, in Figure 29 In the illustrated configuration, only the single-layer metal plate 431f abutting against the positive electrode current collecting portion 420 protrudes toward the front end side with respect to the end portion of the other single-layer metal plates 431f.

[0190] According to Figure 28 (the region surrounded by X) and Figure 29 In the illustrated configuration, since the positional relationship of the current collector 431 with respect to the positive electrode current collecting portion 420 and the position of the joining region 431R can be accurately grasped, the current collector 431 and the positive electrode current collecting portion 420 can be stably joined.

[0191] As illustrated, the end portions of the current collector 431 can be aligned. In this case, the management of the positional relationship of all the single-layer metal plates 431f with respect to the positive electrode current collecting portion 420 becomes easy. Also, in the process of forming the joining region 431R, the operation of the current collector 431 becomes easy. Figure 30

[0192] (Joining configuration of the current collector 431 to the positive electrode tab group 250)

[0193] Referring again to Figure 28 , the joining configuration of the current collector 431 to the positive electrode tab group 250 will be described. The drawing illustrated in the region surrounded by Y in the figure represents one example of the fixed state of the current collector 431 to the positive electrode tab group 250. The first region 431A of the current collector 431 is fixed to the positive electrode tab group 250 with the aid of the positive electrode joining region 200A.

[0194] In the first end portion of the first region 431A of the current collector 431 opposed to the positive electrode tab group 250, surrounded by Y1, a wall thickness portion 431r having a thickness thicker than the inside thereof is provided. Figure 25 and Figure 26 The current collector 431 combined with the configuration of the wall thickness portion 431r provided at the end portion of the single-layer metal plate 431f having a thickness thicker than the inside thereof. Also, the end portion of the single-layer metal plate 431f has a step difference, and the single-layer metal plate 431f located farthest from the positive electrode tab group 250 is located at the foremost end side.

[0195] Thus, when the current collector 431 having the wall thickness portion 431r at the end portion of the single-layer metal plate 431f is used, in the case where the positive electrode tab group 250 is bent (in the direction of the arrow B2 in the figure), even if the end portion of the current collector 431 abuts against the positive electrode tab group 250, the generation of damage to the positive electrode tab group 250 can be suppressed. ​

[0196] Furthermore, by setting a step difference at the end of the current collector 431, the positive electrode tab group 250 abuts against the ends of the multiple single-layer metal plates 431f, which can disperse the load during contact and suppress the damage to the positive electrode tab group 250.

[0197] like Figure 31 As shown in the configuration of the current collector 431, the effect of setting a step difference can be obtained even without the wall thickness portion 431r.

[0198] exist Figure 32 At the end of the first region 431A of the current collector 431 shown, the single-layer metal plate 431f closest to the positive electrode tab group 250 protrudes more than the other single-layer metal plates 431f. The protrusion length L1 of the single-layer metal plate 431f closest to the positive electrode tab group 250 relative to the other single-layer metal plates 431f can be equivalent to the thickness of the current collector 431.

[0199] In this configuration, when the positive electrode tab assembly 250 is bent, the positive electrode tab assembly 250 abuts against the end of a single-layer metal plate 431f. However, since the single-layer metal plate 431f is relatively soft, it is bent together with the positive electrode tab assembly 250 (in the direction of arrow B2 in the figure), thus suppressing the occurrence of damage to the positive electrode tab assembly 250.

[0200] exist Figure 33 The end of the first region 431A of the current collector 431 shown, which faces the positive electrode tab group 250, is pre-bent in a direction separating it from the positive electrode tab group 250 (arrow B4 in the figure). In this configuration, since the positive electrode tab group 250 abuts against the pre-bent area of ​​the first region 431A when the positive electrode tab group 250 is bent, damage to the positive electrode tab group 250 can also be suppressed.

[0201] exist Figure 34 At the end of the first region 431A of the current collector 431 shown, opposite the positive electrode tab group 250, a single-layer metal plate 431f that is in contact with the positive electrode tab group 250 is pre-bent in a direction separate from the positive electrode tab group 250 so as to cover the ends of other stacked single-layer metal plates 431f. (In the direction of arrow B5 in the figure). In this configuration, since the positive electrode tab group 250 abuts against the pre-bent single-layer metal plate 431f when the positive electrode tab group 250 is bent, damage to the positive electrode tab group 250 can also be suppressed.

[0202] (Implementation Method 5)

[0203] Next, refer to Figure 35 andFigure 36 The bending of the current collector 431 and the bending of the positive tab group 250 will be described. In the following description, the relationship between the current collector 431 (first current collector) and the positive tab group 250 (first tab group) will be described, but the relationship between the current collector 432 (second current collector) and the positive tab group 280 is the same.

[0204] In the case where the current collector 431 is bent (arrow R1 in the drawing), the length of the outermost metal plate 4300 (the length in the direction in which the first region 431A and the second region 431B are connected when the current collector 431 is unfolded) can be set to be longer than the length of at least one metal plate 4300 disposed on the inner side thereof.

[0205] In the present embodiment, the current collector 431 shown in FIG. 13 is used, in which the length of the metal plate 4300 located on the outermost circumferential side is the longest, and the length gradually decreases from the outer side to the inner side. Figure 27

[0206] By using the current collector 431 having this configuration, when the current collector 431 is bent, the end portions of the current collector 431 are aligned, and the metal plates 4300 can be prevented from being largely misaligned with each other. In addition, the shape of the bent current collector 431 is stable, and the current collector 431 can be stably disposed in a limited space.

[0207] Referring to FIG. 14, Figure 36 The tab group bent portion of the positive tab group 250 will be described. With respect to the bent portion of the positive tab group 250, the tab group bent portion 250R (region surrounded by X2 in the drawing) can be bent in a direction opposite to the bending direction of the bent portion of the current collector 431 (R1 direction of the region surrounded by X1 in the drawing). It is preferable that the positive tab group 250 and the current collector 431 be welded in a direction in which they are in contact with each other on the inner side of the bending (region in which W1 is in contact in the drawing).

[0208] In this configuration, since the bent portions of the positive tab group 250 and the current collector 431 (region surrounded by X1 in the drawing) do not overlap in the thickness direction of the sealing plate 130, the space around the sealing portion can be reduced. In addition, when a force is applied in the thickness direction of the sealing plate 130, the load applied to the joint portion of the positive tab group 250 and the current collector 431 can be reduced.

[0209] (Embodiment 6)

[0210] Next, referring to FIG. 15, Figures 37-40 The burr MD2 (protruding portion) and the collapse MD1 (curved portion) generated on the outer periphery of the current collector 431 in the manufacturing process of the current collector 431 will be described.

[0211] As shown in FIG. 15,​Figure 24 As shown, in a case where the single-layer metal plates 431f are punched out from the original plate of the metal plate 4300, a burr MD2 and a collapse MD1 along the punching direction can be generated. The burr MD2 is a convex portion toward the punching direction, and the collapse MD1 is a curved portion along the punching direction.

[0212] As shown, in a case where the single-layer metal plates 431f are stacked in a state where the burrs MD2 and the collapses MD1 remain, the single-layer metal plates 431f are difficult to be tightly joined to each other, and a slight gap is likely to be generated between the single-layer metal plates 431f other than the joint portions of the single-layer metal plates 431f to each other. As a result, the current collector bending portion of the current collector 431 can be easily provided. Figure 37 As shown, in the stack in which the single-layer metal plates 431f are stacked, for the region to be joined to the positive electrode current collecting portion 420 (other conductive member), the joint region 431R can be provided in advance by diffusion joining, ultrasonic joining, or the like.

[0213] Figure 38 Even if the joint region 431R is provided, a slight gap remains between the single-layer metal plates 431f other than the joint region 431R. As a result, since the current collector 431 is concentrated in the joint region 431R, the operation at the time of joining to the positive electrode tab group 250 and the positive electrode current collecting portion 420 can be made easy, and the current collector bending portion of the current collector 431 can also be easily formed.

[0214] In the current collector 431, the region to be joined to the positive electrode tab group 250 is preferably joined in a state where the current collector 431 and the positive electrode tab group 250 are strongly clamped by a joining jig (for example, an anvil and a horn in the case of ultrasonic welding) at the time of joining. When a gap is present in the current collector 431, since the current collector 431 is strongly clamped by the joining jig, the joining can also be performed in a state where the gap is eliminated.

[0215] In the current collector 431, the current collector bending portion is preferably located away from the joint region of the single-layer metal plates 431f to each other, the joint portion to the positive electrode current collecting portion 420, or the joint portion to the positive electrode tab group 250, and the single-layer metal plates 431f are not joined to each other.

[0216] As shown, by flattening the lower surface of the single-layer metal plate 431f by removing at least the burr MD2 of the single-layer metal plate 431f (region surrounded by T1 in the drawing), the single-layer metal plates 431f can be stacked without generating a gap. In this case, a plurality of recessed portions are formed in the side surface portion of the current collector 431, respectively, in the stacking direction of the single-layer metal plates 431f.

[0217] As shown, by flattening the lower surface of the single-layer metal plate 431f by removing at least the burr MD2 of the single-layer metal plate 431f (region surrounded by T1 in the drawing), the single-layer metal plates 431f can be stacked without generating a gap. In this case, a plurality of recessed portions are formed in the side surface portion of the current collector 431, respectively, in the stacking direction of the single-layer metal plates 431f. Figure 39

[0218] ​​like Figure 40 As shown, by removing the collapsed edges MD1 and burrs MD2 generated in the single-layer metal plate 431f and chamfering the ends of the single-layer metal plate 431f (the area surrounded by T2 in the figure), the single-layer metal plate 431f can be stacked without gaps. In this case, multiple recesses are also formed, which are separated in the stacking direction of the single-layer metal plate 431f.

[0219] In this way, by forming the current collector 431 in a manner that does not create gaps in the single-layer metal plate 431f, the connection between the positive electrode tab group 250 and the positive electrode current collector 420 can be stabilized.

[0220] In the above description of the implementation method, the positive electrode side was used as an example, but the same configuration can also be used for the negative electrode side.

[0221] Embodiments of the present invention have been described; however, all points of the embodiments disclosed herein should be considered illustrative and not intended to limit the invention. The scope of the invention is defined by the technical solutions and is intended to include equivalents and all modifications within the scope thereof.

Claims

1. A secondary battery, characterized in that, The secondary battery has the following features: An electrode body includes a first electrode and a second electrode with a polarity different from that of the first electrode; The outer casing houses the electrode body; The first electrode tab group has multiple first electrode tabs stacked together and electrically connected to the first electrode; as well as The first current collector is connected to the first electrode group. The first current collector is a first stack of multiple metal plates. The first current collector includes a first region and a second region. The first electrode assembly is engaged in the first region. Other conductive components are joined in the second region. The first current collector includes a current collector bend that is bent between the first region and the second region.

2. The secondary battery according to claim 1, characterized in that, In the current collector bending section, the length of the outermost metal plate is longer than the length of at least one of the metal plates disposed inside it.

3. The secondary battery according to claim 1, characterized in that, In the first laminate, at the first end opposite to the first tab group, the end of the metal plate has a wall thickness portion that is thicker than its inner side.

4. The secondary battery according to claim 1, characterized in that, In the first laminate, at the first end opposite to the first tab group, the end of the metal plate has a stepped portion.

5. The secondary battery according to claim 4, characterized in that, In the first layer, the metal plate closest to the first tab group protrudes beyond the other metal plates.

6. The secondary battery according to claim 1, characterized in that, In the first layer, at the first end opposite to the first tab group, the end of the metal plate is bent in a direction separating from the tab group.

7. The secondary battery according to claim 1, characterized in that, The first tab group has a tab group bending portion that is bent in the opposite direction to the bending direction of the first laminate.

8. The secondary battery according to claim 1, characterized in that, At the front end of the second region of the first laminate, the metal plate that abuts against the other conductive components protrudes further towards the front end than the ends of the other metal plates.

9. The secondary battery according to claim 1, characterized in that, At the front end of the second region of the first stack, from the metal plate furthest from the other conductive components to the metal plate abutting against the other conductive components, the ends of each metal plate gradually protrude.

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