Secondary battery

Abstract

To increase the energy density of a secondary battery.SOLUTION: A first sealing plate 120 has a first end portion 121 and a second end portion 122 located opposite to each other in a second direction orthogonal to a first direction. A negative electrode tab group 220 has a first bent portion 222, and a first tip side region 223 located on a tip side with respect to the first bent portion 222. The negative electrode tab group 220 is bent at a first bent portion 222 such that a tip side with respect to the first bent portion 222 is directed to the second end portion 122 side. The first tip side region 223 is electrically connected to a negative electrode terminal 301. The first sealing plate 120 is provided with a first through hole 123 in which the negative electrode terminal 301 is inserted in the first direction. The first bent portion 222 is located on the first end portion 121 side with respect to a center C of the first sealing plate 120 in the second direction. A center C1 of the first through hole 123 is located on the second end portion 122 side with respect to the center C of the first sealing plate 120 in the second direction.SELECTED DRAWING: Figure 17

Description

[Technical field]

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

[0002] Japanese Patent No. 4537353 (Patent Document 1) is a prior art document that discloses the configuration of a secondary battery. The secondary battery described in Patent Document 1 includes an electrode group, a case, and a current collecting portion. The electrode group is built into the case. The electrode group includes a positive electrode and a negative electrode having uncoated portions where no active material is applied. The uncoated portions of the positive electrode and the negative electrode are provided at the respective ends in the axial direction of the winding of the wound electrode group. The current collecting portion includes an uncoated portion contact portion and a flange portion. The uncoated portion contact portion is fitted into and connected to the uncoated portion. The flange portion is coupled to an electrode terminal to support the electrode terminal. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4537353 Summary of the Invention [Problem to be solved by the invention]

[0004] In the current collector of the secondary battery described in Patent Document 1, the uncoated contact portion and the flange portion are aligned in the winding axis direction of the electrode group, so the width of the current collector for connecting the electrode group and the electrode terminal in the winding axis direction is large. This makes it difficult to ensure a large volume occupied by the electrode body in the battery case, making it difficult to increase the energy density of the secondary battery.

[0005] Furthermore, even when a group of electrode tabs for connecting the electrode body and the current collector is provided at the end of the electrode body, the width occupied by the current collector may become large, so there is room to increase the energy density of the secondary battery.

[0006] The present technology has been made to solve the above-mentioned problems, and has an object to provide a secondary battery that can increase the energy density. [Means for solving the problem]

[0007] The present technology provides the following secondary battery. [1] 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 electrode terminal electrically connected to the first electrode and provided on the case; the electrode body includes a first electrode tab group electrically connected to the first electrode and located at an end of a first side of the electrode body in a first direction, and a second electrode tab group electrically connected to the second electrode and located at an end of a second side opposite to the first side in the first direction, the case includes a case body having a first opening located at an end of the first side in the first direction, and a first sealing plate that seals the first opening, the first sealing plate has a first end and a second end positioned opposite to each other in a second direction perpendicular to the first direction, the first electrode tab group has a first curved portion that is bundled and curved, and a first tip side region that is located on a tip side of the first curved portion, the first electrode tab group is curved at the first curved portion such that a tip side of the first curved portion faces the second end side, the first tip side region is electrically connected to the first electrode terminal, the first sealing plate is provided with a first through hole through which the first electrode terminal is inserted in the first direction, the first curved portion is located closer to the first end portion than a center of the first sealing plate in the second direction, a center of the first through hole is located closer to the second end than a center of the first sealing plate in the second direction. [2] a second electrode terminal electrically connected to the second electrode and provided on the case; the case includes a second sealing plate, the case body has a second opening located at an end of the second side in the first direction, the second sealing plate seals the second opening, the second sealing plate has a third end and a fourth end positioned opposite to each other in the second direction, the second electrode tab group has a second curved portion that is bundled and curved, and a second tip side region that is located on the tip side of the second curved portion, the second electrode tab group is curved at the second curved portion such that a tip side of the second curved portion is directed toward the second end portion, the second tip side region is electrically connected to the second electrode terminal, the second sealing plate is provided with a second through hole through which the second electrode terminal is inserted in the first direction, the second curved portion is located closer to the third end portion than a center of the second sealing plate in the second direction, The secondary battery according to [1], wherein a center of the second through hole is located closer to the fourth end portion than a center of the second sealing plate in the second direction. [3] The secondary battery according to [2], wherein in the second direction, the first end and the third end are located on the same end side. [4] a first current collecting member electrically connecting the first electrode terminal and the first electrode tab group; the first current collecting member includes a first component and a second component, the second component is connected to the first electrode terminal; the first component has a first region connected to the second component and a second region connected to the first electrode tab group, a step portion is provided between the first region and the second region, which makes the first region and the second region different in position in the first direction; The secondary battery according to any one of [1] to [3], wherein the step portion extends along a third direction perpendicular to the first direction and the second direction. [5] The secondary battery according to [4], wherein the second region of the first component is disposed along the first sealing plate. [6] a resin member disposed between the first electrode terminal and the first sealing plate, the first sealing plate further has a covering portion that covers the end portion of the first side of the case body from the first direction, The secondary battery according to any one of [1] to [5], wherein the covering portion and the case body are joined by welding. Effect of the Invention

[0008] According to the present technology, it is possible to increase the energy density of a secondary battery. [Brief description of the drawings]

[0009] [Figure 1] 1 is a front view showing a configuration of a secondary battery according to an embodiment of the present technology; [Diagram 2] 2 is a diagram showing the secondary battery shown in FIG. 1 as viewed from the direction of arrow II. [Diagram 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. [Diagram 5] 2 is a front cross-sectional view of the secondary battery shown in FIG. [Figure 6] FIG. 2 is a front view showing a negative electrode original plate before the negative electrode plate is formed. [Figure 7] 7 is a cross-sectional view taken along the line VII-VII of the negative electrode original plate shown in FIG. 6. [Figure 8] FIG. 2 is a front view showing a negative electrode plate formed from the negative electrode original plate. [Figure 9] FIG. 2 is a front view showing a positive electrode original plate before the positive electrode plate is formed. [Figure 10]10 is a cross-sectional view taken along the line XX in FIG. 9 . [Figure 11] FIG. 2 is a front view showing a positive electrode plate formed from a positive electrode original plate. [Figure 12] FIG. 2 is a diagram showing an electrode assembly and a current collector taken out from a secondary battery. [Figure 13] FIG. 4 is a front view of a connection structure between a negative electrode tab group and a negative electrode current collector. [Figure 14] FIG. 4 is a cross-sectional view of a connection structure between a negative electrode tab group and a negative electrode current collector. [Figure 15] 11A to 11C are diagrams showing a process of inserting the electrode body into the case body. [Figure 16] 11A and 11B are diagrams showing a step of arranging a spacer between the sealing plate and the electrode body. [Figure 17] 1 is a partial cross-sectional view of a secondary battery according to an embodiment, as viewed from above; [Figure 18] 11 is a perspective view showing a joined state between a case body and a first sealing plate included in a secondary battery according to a first modified example of the embodiment. FIG. [Figure 19] FIG. 11 is a partial cross-sectional view showing a configuration of a secondary battery according to a second modified example of the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] 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 will not be repeated.

[0011] In the embodiments described below, when referring to the number, amount, etc., the scope of the present technology is not necessarily limited to the number, amount, etc., unless otherwise specified. In addition, in the following embodiments, each component is not necessarily essential to the present technology, unless otherwise specified. In addition, the present technology is not necessarily limited to those that achieve all of the effects and advantages mentioned in the present embodiment.

[0012] In this specification, the words "comprise", "include" and "have" are open-ended, i.e., when a certain configuration is included, other configurations may or may not be included.

[0013] Furthermore, 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 one state, and the relative positional relationships can be inverted or rotated to any angle depending on the installation direction of each mechanism (for example, by turning the entire mechanism upside down).

[0014] In this specification, the term "secondary battery" is not limited to lithium ion batteries, but may include other secondary batteries such as nickel-metal hydride batteries and sodium ion batteries. In this specification, the term "electrode" may collectively refer to a positive electrode and a negative electrode.

[0015] In the drawings, the direction along the winding axis of the electrode body of the secondary battery is the X direction as a first direction, the Y direction is the short side direction of the electrode body that is perpendicular to the first direction and seen from the first direction as a second direction, and the Z direction is the long side direction of the electrode body that is perpendicular to the first direction and seen from the first direction as a third direction. In addition, in order to make the invention easier to understand, the dimensions of each component in the drawings are sometimes shown differently from the actual dimensions.

[0016] In this specification, the first direction (X direction) may be referred to as the "width direction" of the secondary battery or the case body, the second direction (Y direction) may be referred to as the "thickness direction" of the secondary battery or the case body, and the third direction (Z direction) may be referred to as the "height direction" of the secondary battery or the case body.

[0017] (Overall battery configuration) Fig. 1 is a front view of a secondary battery 1 according to the present embodiment. Figs. 2 to 4 are views of the secondary battery 1 shown in Fig. 1 as viewed from the directions of arrows II, III, and IV, respectively. Fig. 5 is a front cross-sectional view of the secondary battery 1 shown in Fig. 1.

[0018] 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 on a vehicle.

[0019] 1 to 5, 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 first sealing plate 120, and a second sealing plate .

[0020] When configuring an assembled battery including the secondary batteries 1, multiple secondary batteries 1 are stacked in their thickness direction. The stacked secondary batteries 1 may be constrained in the stacking direction (Y direction) by a restraining member to form a battery module, or the assembled battery may be directly supported on the side surface of a battery pack case without using a restraining member.

[0021] 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.

[0022] 1 and 2, a first sealing plate 120 and a second sealing plate 130 are provided at both ends of the case body. The case body 110 can be formed into a square tube shape, for example, by abutting the edges of bent plate-like members (joints 115 shown in FIG. 2) and joining them together (for example, by laser welding). The corners of the "square tube" may have a rounded shape.

[0023] In this embodiment, the case body 110 is formed to be 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 a relatively large (high capacity) secondary battery 1 to be configured. 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 a relatively low height (low height) secondary battery 1 to be configured, improving the mountability in a vehicle, for example.

[0024] 3, a first opening 113 is provided at an end of a first side in a first direction (X direction) of case body 110. First opening 113 is sealed by a first sealing plate 120. First opening 113 and first sealing plate 120 have a substantially rectangular shape with a short side direction in the Y direction and a long side direction in the Z direction. First sealing plate 120 has a first end 121 and a second end 122 located on opposite sides to each other in a second direction (Y direction).

[0025] A negative electrode terminal 301 (first electrode terminal), a liquid injection hole 124, and a gas exhaust valve 125 are provided on the first sealing plate 120. The positions of the negative electrode terminal 301, the liquid injection hole 124, and the gas exhaust valve 125 can be changed as appropriate.

[0026] 4, a second opening 114 is provided at an end of the case body 110 on the second side in the first direction (X direction). The second opening 114 is sealed by a second sealing plate 130. The second opening 114 and the second 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. The second sealing plate 130 has a third end 131 and a fourth end 132 located on opposite sides to each other in the second direction.

[0027] A positive electrode terminal 302 (second electrode terminal), a liquid injection hole 134, and a gas exhaust valve 135 are provided on the second sealing plate 130. The positions of the positive electrode terminal 302, the liquid injection hole 134, and the gas exhaust valve 135 can be changed as appropriate.

[0028] 3 and 4, in the second direction (Y direction), the first end 121 of the first sealing plate 120 and the third end 131 of the second sealing plate 130 are located on the same end side. Also, in the second direction (Y direction), the second end 122 of the first sealing plate 120 and the fourth end 132 of the second sealing plate 130 are located on the same end side.

[0029] The first sealing plate 120 and the second sealing plate 130 are made of metal. Specifically, the first sealing plate 120 and the second sealing plate 130 are made of aluminum, an aluminum alloy, iron, an iron alloy, or the like.

[0030] The negative electrode terminal 301 is electrically connected to the negative electrode of the electrode body 200. The negative electrode terminal 301 is located on the outer surface of the first sealing plate 120, that is, the outer surface of the case 100.

[0031] The positive electrode terminal 302 is electrically connected to the positive electrode of the electrode body 200. The positive electrode terminal 302 is located on the outer surface of the second sealing plate 130, i.e., the outer surface of the case 100.

[0032] The negative 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 terminal 301 may be provided with a portion or layer made of aluminum or an aluminum alloy.

[0033] The positive terminal 302 is made of a conductive material (more specifically, a metal), and may be made of, for example, aluminum or an aluminum alloy.

[0034] The liquid inlet holes 124 and 134 are sealed by a sealing member (not shown) which may be, for example, a blind rivet or other metal member.

[0035] The gas exhaust valves 125, 135 break when the pressure inside the case 100 reaches or exceeds a predetermined value, and exhaust the gas inside the case 100 to the outside.

[0036] The electrode body 200 is a flat-shaped electrode body having a positive electrode plate and a negative electrode plate, which will be described later. Specifically, the electrode body 200 is a wound-type electrode body in which a band-shaped positive electrode plate and a band-shaped negative electrode plate are both wound via a band-shaped separator (not shown). However, in this specification, the "electrode body" is not limited to a wound-type electrode body, and may be a laminated electrode body in which a plurality of positive electrode plates and a plurality of negative electrode plates are alternately laminated. The electrode body may include a plurality of positive electrode plates and a plurality of negative electrode plates, and the positive electrode tabs provided on each positive electrode plate may be laminated to form a positive electrode tab group, or the negative electrode tabs provided on each negative electrode plate may be laminated to form a negative electrode tab group.

[0037] 5, case 100 houses electrode assembly 200. Electrode assembly 200 is housed in case 100 so that its winding axis is parallel to the X direction.

[0038] Specifically, one or more wound electrode bodies are housed together with an electrolytic solution (electrolyte) (not shown) inside an insulating sheet 700 (described later) arranged in the case 100. As the electrolytic solution (non-aqueous electrolytic solution), for example, LiPF6 dissolved at a concentration of 1.2 mol / L in a non-aqueous solvent in which ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed in a volume ratio (25°C) of 30:30:40 can be used. Note that a solid electrolyte may be used instead of the electrolytic solution.

[0039] The electrode assembly 200 includes a negative electrode tab group 220 (first electrode tab group) and a positive electrode tab group 250 (second electrode tab group). The negative electrode tab group 220 is located at the end of a first side of the electrode assembly 200 in a first direction (X direction). The first side in this embodiment is the first sealing plate 120 side. The positive electrode tab group 250 is located at the end of a second side opposite to the first side in the first direction (X direction). The second side in this embodiment is the second sealing plate 130 side.

[0040] The negative electrode tab group 220 and the positive electrode tab group 250 are formed so as to protrude from the central portion of the electrode body 200 toward the first sealing plate 120 or the second sealing plate 130, respectively. Note that the manner in which the negative electrode tab group 220 and the positive electrode tab group 250 protrude is not limited to this form.

[0041] The current collector 400 includes a negative electrode current collector 410 (first current collector) and a positive electrode current collector 420 (second current collector). The negative electrode current collector 410 and the positive electrode current collector 420 are each made of a plate-shaped member. The electrode body 200 is electrically connected to the negative electrode terminal 301 and the positive electrode terminal 302 via the current collector 400. The negative electrode tab group 220 can also be directly connected to the negative electrode terminal 301. The positive electrode tab group 250 can also be directly connected to the positive electrode terminal 302.

[0042] The negative electrode current collector 410 is disposed on the first sealing plate 120 via a resin insulating member. The negative electrode current collector 410 is electrically connected to the negative electrode tab group 220 and the negative electrode terminal 301. The negative electrode current collector 410 is made of a conductive material (more specifically, a metal), and may be made of, for example, copper or a copper alloy.

[0043] Positive electrode current collector 420 is disposed on second sealing plate 130 via a resin insulating member. Positive electrode current collector 420 is electrically connected to positive electrode tab group 250 and positive electrode terminal 302. Positive electrode current collector 420 is made of a conductive material (more specifically, a metal), and may be made of, for example, aluminum or an aluminum alloy.

[0044] (Configuration of electrode body 200) FIG. 6 is a front view showing the negative electrode original plate 210S before the negative electrode plate 210 (first electrode) is formed, FIG. 7 is a cross-sectional view taken along line VII-VII of the negative electrode original plate 210S shown in FIG. 6, and FIG. 8 is a front view showing the negative electrode plate 210 formed from the negative electrode original plate 210S.

[0045] The negative electrode plate 210 is manufactured by processing a negative electrode original plate 210S. As shown in Figures 6 and 7, the negative electrode original plate 210S 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.

[0046] A negative electrode active material layer 212 is formed on both sides of the negative electrode core 211 except for one end portion. The negative electrode active material layer 212 is formed by applying a negative electrode active material layer slurry with a die coater.

[0047] The negative electrode active material layer slurry is prepared by kneading graphite as the negative electrode active material, styrene butadiene rubber (SBR) and carboxymethyl cellulose (CMC) as binders, and water as a dispersion medium so that the mass ratio of graphite:SBR:CMC is approximately 98:1:1.

[0048] The negative electrode core 211 coated with the negative electrode active material layer slurry is dried to remove water contained in the negative electrode active material layer slurry, thereby forming the negative electrode active material layer 212. Furthermore, the negative electrode active material layer 212 is compressed to form a negative electrode original plate 210S including the negative electrode core 211 and the negative electrode active material layer 212. The negative electrode original plate 210S is cut into a predetermined shape to form the negative electrode plate 210. The negative electrode original plate 210S can be cut by laser processing using energy beam irradiation, die processing, cutter processing, or the like.

[0049] As shown in FIG. 8, a plurality of negative electrode tabs 230 made of a negative electrode core 211 are provided at one end in the width direction of a negative electrode plate 210 formed from a negative electrode original plate 210S. When the negative electrode plate 210 is wound, the plurality of negative electrode tabs 230 are stacked to form a negative electrode tab group 220. As a result, the negative electrode tab group 220 is connected to the negative electrode plate 210 (first electrode). The position and length in the protruding direction of each of the plurality of negative electrode tabs 230 are appropriately adjusted in consideration of the state in which the negative electrode tab group 220 is connected to the negative electrode current collector 410. The shape of the negative electrode tab 230 is not limited to the one exemplified in FIG. 8.

[0050] FIG. 9 is a front view showing the positive electrode original plate 240S before the positive electrode plate 240 (second electrode) is formed, FIG. 10 is a cross-sectional view taken along line XX of the positive electrode original plate 240S shown in FIG. 9, and FIG. 11 is a front view showing the positive electrode plate 240 formed from the positive electrode original plate 240S.

[0051] The positive electrode plate 240, which is the second electrode, has a polarity different from that of the negative electrode plate 210, which is the first electrode. The positive electrode plate 240 is manufactured by processing a positive electrode original plate 240S. As shown in Fig. 9 and Fig. 10, the positive electrode original plate 240S includes a positive electrode core body 241, a positive electrode active material layer 242, and a positive electrode protective layer 243. The positive electrode core body 241 is an aluminum foil or an aluminum alloy foil.

[0052] A positive electrode active material layer 242 is formed on both sides of the positive electrode core 241 except for one end portion. The positive electrode active material layer 242 is formed on the positive electrode core 241 by applying a positive electrode active material layer slurry with a die coater.

[0053] The positive electrode active material layer slurry is prepared by kneading lithium nickel cobalt manganese composite oxide as the positive electrode active material, polyvinylidene fluoride (PVdF) as a binder, a carbon material as a conductive material, and N-methyl-2-pyrrolidone (NMP) as a dispersion medium, so that the mass ratio of lithium nickel cobalt manganese composite oxide:PVdF:carbon material is approximately 97.5:1:1.5.

[0054] The positive electrode protective layer 243 is in contact with the positive electrode core 241 and is formed at one end in the width direction of the positive electrode active material layer 242. The positive electrode protective layer 243 is formed on the positive electrode core 241 by applying a positive electrode protective layer slurry with a die coater. The positive electrode protective layer 243 has a larger electric resistance than the positive electrode active material layer 242.

[0055] The positive electrode protective layer slurry is prepared by kneading alumina powder, a carbon material as a conductive material, PVdF as a binder, and NMP as a dispersion medium so that the mass ratio of alumina powder:carbon material:PVdF is approximately 83:3:14.

[0056] The positive electrode core 241 coated with the positive electrode active material layer slurry and the positive electrode protective layer slurry is dried, and the NMP contained in the positive electrode active material layer slurry and the positive electrode protective layer slurry is removed to form the positive electrode active material layer 242 and the positive electrode protective layer 243. Furthermore, the positive electrode active material layer 242 is compressed to form a positive electrode original plate 240S including the positive electrode core 241, the positive electrode active material layer 242, and the positive electrode protective layer 243. The positive electrode original plate 240S is cut into a predetermined shape to form the positive electrode plate 240. The positive electrode original plate 240S can be cut by laser processing using energy beam irradiation, die processing, cutter processing, or the like.

[0057] As shown in FIG. 11, a plurality of positive electrode tabs 260 made of a positive electrode core 241 are provided at one end in the width direction of the positive electrode plate 240 formed from the positive electrode original plate 240S. When the positive electrode plate 240 is wound, the plurality of positive electrode tabs 260 are stacked to form a positive electrode tab group 250. As a result, the positive electrode tab group 250 is connected to the positive electrode plate 240 (second electrode). The position and length in the protruding direction of each of the plurality of positive electrode tabs 260 are appropriately adjusted in consideration of the state in which the positive electrode tab group 250 is connected to the positive electrode current collector 420. The shape of the positive electrode tab 260 is not limited to the one exemplified in FIG. 11.

[0058] A positive electrode protection layer 243 is provided at the base of each of the positive electrode tabs 260. The positive electrode protection layer 243 does not necessarily have to be provided at the base of the positive electrode tab 260.

[0059] 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.

[0060] (Connection structure between electrode body 200 and current collector 400) Fig. 12 is a diagram showing the electrode body 200 and the current collector 400 taken out from the secondary battery 1. As shown in Fig. 12, the electrode body 200 is formed by stacking two electrode bodies 201, 202, each of which is a wound type electrode body. In the example shown in Fig. 12, a structure in which two wound type electrode bodies are stacked is shown, but the electrode body 200 may be composed of one wound type electrode body, may be composed of three or more wound type electrode bodies, or may be composed of a laminated type electrode body.

[0061] The negative electrode tab group 220 is joined to the negative electrode current collector 410 at a joint 434 , and the positive electrode tab group 250 is joined to the positive electrode current collector 420 at a joint 454 .

[0062] Fig. 13 is a front view of the connection structure between the negative electrode tab group and the negative electrode current collector, and Fig. 14 is a cross-sectional view of the connection structure between the negative electrode tab group and the negative electrode current collector.

[0063] 13 and 14, the negative electrode current collector 410 electrically connects the negative electrode terminal 301 and the negative electrode tab group 220. The negative electrode current collector 410 in this embodiment is connected to the negative electrode terminal 301 between the electrode body 200 and the first sealing plate 120.

[0064] The negative electrode current collector 410 includes a first conductive member 430 (first part) and a second conductive member 440 (second part). The first conductive member 430 and the second conductive member 440 are joined at a joint 433. The first conductive member 430 and the second conductive member 440 are joined by, for example, laser welding.

[0065] The first conductive member 430 is joined to the negative electrode tab group 220 at a joint 434. The joint 434 can be formed by, for example, ultrasonic welding, resistance welding, laser welding, crimping, or the like. In the present embodiment, the first conductive member 430 and the negative electrode tab group 220 are joined by, for example, ultrasonic bonding.

[0066] Second conductive member 440 is connected to negative terminal 301 at joint 441. Joint 441 may be formed by, for example, ultrasonic welding, resistance welding, laser welding, crimping, or the like. In this embodiment, negative terminal 301 and second conductive member 440 are joined by, for example, providing a through hole in second conductive member 440, inserting negative terminal 301 into the through hole, crimping negative terminal 301 on second conductive member 440, and then welding the crimped portion to second conductive member 440.

[0067] The first conductive member 430 has a first region 431 and a second region 432. The first region 431 is connected to the second conductive member 440. The second region 432 is connected to the negative electrode tab group 220. The second region 432 is disposed along the first sealing plate 120.

[0068] A step portion 435 is provided between the first region 431 and the second region 432. The step portion 435 makes the positions of the first region 431 and the second region 432 in the first direction (X direction) different from each other after the secondary battery 1 is assembled. This allows the first region 431 and the second region 432 to be arranged side by side in one direction. The step portion 435 extends along the third direction (Z direction).

[0069] A first insulating member 510 (resin member) is disposed between the negative electrode terminal 301 and the first sealing plate 120. A second insulating member 520 (resin member) is disposed between the first sealing plate 120 and the first conductive member 430 and the second conductive member 440. The first insulating member 510 and the second insulating member 520 may be an integrated part.

[0070] Negative electrode terminal 301 is attached to first sealing plate 120 via first insulating member 510. Negative electrode terminal 301 is provided so as to be exposed to the outside of first sealing plate 120 and to reach second conductive member 440 of negative electrode current collector 410 provided on the inner surface side of first sealing plate 120.

[0071] The procedure for assembling each part is as follows: first, the negative electrode terminal 301 and the second conductive member 440 are attached to the first sealing plate 120 together with the first insulating member 510 and the second insulating member 520. Next, the first conductive member 430 electrically connected to the electrode body 200 is attached to the second conductive member 440. At this time, the first conductive member 430 is placed on the first insulating member 510 such that a portion of the first conductive member 430 overlaps with the second conductive member 440. Next, the first conductive member 430 and the second conductive member 440 are connected by welding at the joint 434.

[0072] However, negative electrode terminal 301 may be electrically connected to first sealing plate 120. Also, first sealing plate 120 may play the role of negative electrode terminal 301.

[0073] 13 and 14, the negative electrode current collector 410 is illustrated as being made up of two components (the first conductive member 430 and the second conductive member 440), but the negative electrode current collector 410 may be made up of a single component.

[0074] Although the connection structure on the negative electrode side is shown in FIG. 13 and FIG. 14, the basic connection structure on the positive electrode side is similar to that on the negative electrode side.

[0075] (Step of Inserting the Electrode Body 200) 15 is a diagram showing a process of inserting the electrode body 200 into the case body 110. As shown in FIG.

[0076] The insulating sheet 700 may be made of, for example, resin. More specifically, the material of the insulating sheet 700 may be, for example, polypropylene (PP), polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polyimide (PI), or polyolefin (PO).

[0077] The insulating sheet 700 does not necessarily have to cover the entire surface of the electrode body 200. The insulating sheet 700 preferably covers an area of ​​about 50% or more, and more preferably about 70% or more, of the outer surface of the electrode body. Of the six faces of the approximately rectangular parallelepiped (flat) electrode body 200, the insulating sheet 700 preferably covers the entire four faces other than the two faces on which the negative electrode tab group 220 and the positive electrode tab group 250 are formed, respectively.

[0078] Before the step of inserting the electrode body 200 into the case body 110, the first sealing plate 120, the negative electrode terminal 301, and the negative electrode tab group 220 are each joined. After the step of inserting the electrode body 200 into the case body 110, the second sealing plate 130, the positive electrode terminal 302, and the positive electrode tab group 250 are each joined.

[0079] FIG. 16 is a diagram showing a process of placing a spacer 600 between the first sealing plate 120 and the electrode body 200. As shown in FIG.

[0080] 16, the negative electrode tab group 220 arranged from the electrode body 200 toward the first sealing plate 120 is curved from the center in the Y direction of the first sealing plate 120 toward the end, and then folded back toward the center. A spacer 600 is provided to accommodate the curved portion of the negative electrode tab group 220. The configuration of the negative electrode tab group 220 will be described in detail later.

[0081] The spacer 600 includes a first spacer 610 and a second spacer 620. The first spacer 610 and the second spacer 620 are engaged with each other by engagement portions 630a, 630b when each of them is slid along the Y direction from the end side toward the center side of the first sealing plate 120. As a result, the spacer 600 is fixed to the first sealing plate 120 via the first insulating member 510, and the positional stability of the spacer 600 is increased.

[0082] (Joint structure between electrode body 200 and electrode terminal 300) 17 is a partial cross-sectional view of a secondary battery according to one embodiment as viewed from above. As shown in FIG. 17, a negative electrode tab group 220 in an electrode body 200 has a base portion 221, a first curved portion 222, and a first tip side region 223.

[0083] The root portion 221 is a portion of the negative electrode tab group 220 that is adjacent to the negative electrode plate. In the root portion 221, a plurality of negative electrode tabs extending from the negative electrode plate to the end of the first side (first sealing plate 120 side) in the first direction (X direction) are bundled toward the end of the first side.

[0084] A plurality of negative electrode tabs are bundled and stacked in the first curved portion 222. The first curved portion 222 is connected to an end portion of the base portion 221 on a first side in the first direction (X direction).

[0085] The negative electrode tab group 220 is curved at the first curved portion 222 such that the tip side from the first curved portion 222 faces the second end 122 in the second direction (Y direction). The first curved portions 222 are bundled and curved so as to be folded back toward the opposite side in the second direction (Y direction). The first curved portions 222 in this embodiment are curved from the root portion 221 toward the first end 121 in the second direction (Y direction), and then folded back toward the second end 122 and bundled.

[0086] The first curved portion 222 is located on the first end 121 side of the center C of the first sealing plate 120 in the second direction (Y direction). Note that the first curved portion 222 in the present embodiment is located on the first end 121 side of the center C of the first sealing plate 120 including the portion that is bundled and extends linearly in the second direction (Y direction), but is not limited to this configuration. The first curved portion 222 may be configured such that at least only the curved portion is located on the first end 121 side of the center C of the first sealing plate 120.

[0087] The first tip side region 223 is a region of the negative electrode tab group 220 that is located closer to the tip side than the first curved portion 222. The first tip side region 223 in this embodiment is electrically connected to the negative electrode terminal 301 via the negative electrode current collector 410. The first tip side region 223 is joined to a first conductive member 430 of the negative electrode current collector 410.

[0088] The first sealing plate 120 is provided with a first through hole 123 through which the negative electrode terminal 301 is inserted in a first direction (X direction). The center C1 of the first through hole 123 is located on the second end 122 side of the center C of the first sealing plate 120 in the second direction (Y direction). Note that the entire opening of the first through hole 123 is located on the second end 122 side of the center C of the first sealing plate 120, but is not limited to this configuration. The center C1 of the first through hole 123 may be located on the second end 122 side of the center C of the first sealing plate 120, and a part of the opening of the hole may be located on the first end 121 side of the center C of the first sealing plate 120.

[0089] It is desirable that the first through hole 123 has a perfect circular shape. However, the first through hole 123 may have a square shape, an ellipse shape, a track shape, etc. In the case of these shapes, the center C1 of the first through hole 123 is the center of gravity position when viewed from the first direction (X direction).

[0090] Since the center C1 of the first through hole 123 is located on the second end 122 side of the center C of the first sealing plate 120 in the second direction (Y direction), the central axis of the negative electrode terminal 301 disposed inside the first through hole 123 is also located on the second end 122 side of the center C of the first sealing plate 120 in the second direction (Y direction). As a result, the negative electrode terminal 301 and the first curved portion 222 of the negative electrode tab group 220 are disposed so as not to overlap in the first direction (X direction).

[0091] Note that the first curved portion 222 may be arranged to overlap in the second direction (Y direction) with a portion of the negative electrode terminal 301 joined to the negative electrode current collector 410, depending on the degree of curvature of the negative electrode tab group 220. Also, the negative electrode terminal 301 does not necessarily have to extend in the first direction (X direction) in a portion located from the first through-hole 123 to the outer surface of the first sealing plate 120.

[0092] The positive electrode tab group 250 in the electrode body 200 has a root portion 251 , a second curved portion 252 , and a second tip side region 253 .

[0093] The root portion 251 is a portion adjacent to the positive electrode plate of the positive electrode tab group 250. In the root portion 251, a plurality of positive electrode tabs extending in the first direction from the second electrode to the end portion on the second side (the second sealing plate 130 side) are bundled toward the end portion on the second side.

[0094] The second curved portion 252 is formed by bundling and stacking a plurality of positive electrode tabs. The second curved portion 252 is connected to an end portion of the base portion 251 on the second side in the first direction (X direction).

[0095] The positive electrode tab group 250 is curved at the second curved portion 252 such that the tip side from the second curved portion 252 faces the fourth end 132 in the second direction (Y direction). The second curved portion 252 is bundled and curved so as to be folded back toward the opposite side in the second direction (Y direction). The second curved portion 252 in this embodiment is curved from the base portion 251 toward the third end 131 in the second direction (Y direction), and then folded back toward the fourth end 132 and bundled.

[0096] The second curved portion 252 is located on the third end 131 side of the center C of the second sealing plate 130 in the second direction (Y direction). Note that the second curved portion 252 in the present embodiment is located on the third end 131 side of the center C of the second sealing plate 130 including the portion that is bundled and extends linearly in the second direction (Y direction), but is not limited to this configuration. The second curved portion 252 may be configured such that at least only the curved portion is located on the third end 131 side of the center C of the second sealing plate 130.

[0097] The second tip side region 253 is a region of the positive electrode tab group 250 that is located closer to the tip side than the second curved portion 252. The second tip side region 253 in the present embodiment is electrically connected to the positive electrode terminal 302 via the positive electrode current collector 420.

[0098] In this embodiment, the first curved portion 222 and the second curved portion 252 are bent to the same side in the second direction (Y direction). Therefore, when the first curved portion 222 and the second curved portion 252 are bent to form, the bending directions are unified, making the bending process easy. The first curved portion 222 and the second curved portion 252 may be configured to be bent to opposite sides to each other in the second direction (Y direction).

[0099] The second sealing plate 130 is provided with a second through hole 133 through which the positive electrode terminal 302 is inserted in the first direction (X direction). The center C2 of the second through hole 133 is located on the fourth end 132 side from the center C of the second sealing plate 130 in the second direction (Y direction). Note that the entire opening of the second through hole 133 is located on the fourth end 132 side from the center C of the second sealing plate 130, but is not limited to this configuration. The center C2 of the second through hole 133 may be located on the fourth end 132 side from the center C of the second sealing plate 130, and a part of the opening of the hole may be located on the third end 131 side from the center C of the second sealing plate 130.

[0100] The second through hole 133 is preferably in a perfect circular shape. However, the second through hole 133 may be in a square shape, an ellipse shape, a track shape, etc. In the case of these shapes, the center C2 of the second through hole 133 is the center of gravity position when viewed from the first direction (X direction).

[0101] In the present embodiment, the first through hole 123 and the second through hole 133 are provided on the same side in the second direction (Y direction) when viewed from the center C of the first sealing plate 120 and the second sealing plate 130. This results in a configuration that facilitates electrical connection between the first curved portion 222 and the second curved portion 252 when they are bent to the same side in the second direction (Y direction).

[0102] Since the center C2 of the second through hole 133 is located on the fourth end 132 side from the center C of the second sealing plate 130 in the second direction (Y direction), the positive electrode terminal 302 disposed inside the second through hole 133 is also located on the fourth end 132 side from the center C of the second sealing plate 130 in the second direction (Y direction). As a result, the positive electrode terminal 302 and the second curved portion 252 of the positive electrode tab group 250 are disposed so as not to overlap in the first direction (X direction).

[0103] Note that the second curved portion 252 may be arranged to overlap in the second direction (Y direction) with a portion of the positive electrode terminal 302 that is joined to the positive electrode current collector 420, depending on the degree of curvature of the positive electrode tab group 250. Also, the positive electrode terminal 302 does not necessarily have to extend in the first direction (X direction) in a portion located from the second through-hole 133 to the outer surface of the second sealing plate 130.

[0104] As shown in FIG. 17, in the secondary battery 1 according to one embodiment, the negative terminal 301 and the first curved portion 222 of the negative tab group 220 are arranged so as not to overlap in the first direction (X direction). That is, the negative terminal 301 and the first curved portion 222 are arranged to be shifted in the second direction (Y direction) when viewed from the first direction (X direction). This makes it possible to configure the negative terminal 301 and the first curved portion 222 so as not to interfere with each other in the first direction (X direction). Therefore, the occupied width W1 of the first curved portion 222, the negative current collector 410, and the negative terminal 301 in the first direction (X direction) in the case 100 can be made narrower. As a result, the occupied volume of the negative plate and the positive plate of the electrode body 200 in the case 100 can be increased, and the energy density of the secondary battery 1 can be increased.

[0105] Furthermore, by arranging the first curved portion 222 on the first end 121 side, the negative electrode tab group 220 is easier to bend and the first curved portion 222 is easier to form compared to a configuration in which the first curved portion is arranged near the center C in the second direction (Y direction), so that the secondary battery 1 can be manufactured efficiently.

[0106] Although the connection structure on the negative electrode side of the secondary battery in this embodiment has been described, the connection structure on the positive electrode side is similar to that on the negative electrode side.

[0107] In the secondary battery 1 according to an embodiment of the present technology, the first curved portion 222 of the negative electrode tab group 220 of the electrode body 200 and the center C1 of the first through hole 123 through which the negative electrode terminal 301 is inserted are arranged so as not to overlap in the first direction (X direction). This allows the first curved portion 222 and the negative electrode terminal 301 to be configured not to interfere with each other in the first direction (X direction). Therefore, compared to a case in which the first curved portion 222 and the negative electrode terminal 301 arranged in the first through hole 123 are arranged so as to overlap in the first direction (X direction), the occupied width W1 of the negative electrode tab group 220 and the negative electrode terminal 301 in the first direction (X direction) can be narrowed. As a result, the occupied volume of the negative electrode plate and the positive electrode plate of the electrode body 200 in the case 100 can be increased, and the energy density of the secondary battery 1 can be improved.

[0108] In the secondary battery 1 according to an embodiment of the present technology, similarly to the configuration of the negative electrode side, the second curved portion 252 of the positive electrode tab group 250 of the electrode body 200 and the center C2 of the second through hole 133 through which the positive electrode terminal 302 is inserted are arranged so as not to overlap in the first direction (X direction). This makes it possible to configure the second curved portion 252 and the positive electrode terminal 302 so as not to interfere with each other in the first direction (X direction). Therefore, compared to the case in which the second curved portion 252 and the positive electrode terminal 302 arranged in the second through hole 133 are arranged so as to overlap in the first direction (X direction), the occupied width W1 of the positive electrode tab group 250 and the positive electrode terminal 302 in the first direction (X direction) can be narrowed. As a result, the occupied volume of the negative electrode plate and the positive electrode plate of the electrode body 200 in the case 100 can be increased, and the energy density of the secondary battery 1 can be improved.

[0109] In a secondary battery 1 according to one embodiment of the present technology, by forming the first curved portion 222 of the negative electrode tab group 220 and the second curved portion 252 of the positive electrode tab group 250 in the same bending direction, it is possible to stably bend the curved portions more easily than in the case where the first curved portion 222 and the second curved portion 252 are bent in opposite directions, thereby enabling the electrode body 200 to be manufactured efficiently.

[0110] In the secondary battery 1 according to the embodiment of the present technology, the step portion 435 is provided between the first region 431 and the second region 432 of the first conductive member 430 of the negative electrode current collector 410, so that the positions of the first region 431 and the second region 432 in the first direction (X direction) can be made different. Therefore, the first region 431 and the second conductive member 440 of the first conductive member 430 of the negative electrode current collector 410 can be overlapped in the second direction (Y direction), and the second region 432 of the first conductive member 430 can be disposed closer to the first sealing plate 120. This makes it possible to narrow the occupied width W1 of the negative electrode tab group 220, the negative electrode current collector 410, and the negative electrode terminal 301 in the first direction (X direction). As a result, the occupied volume of the negative electrode plate and the positive electrode plate of the electrode body 200 in the case 100 can be increased, so that the energy density of the secondary battery 1 can be improved. It should be noted that the positive electrode current collector 420 also has the same structure as the negative electrode current collector 410, and thereby achieves the same effects.

[0111] In the secondary battery 1 according to an embodiment of the present technology, the second region 432 of the first conductive member 430 of the negative electrode current collector 410 is disposed to face each other along the first sealing plate 120, thereby making it possible to narrow the occupied width W1 of the negative electrode tab group 220, the negative electrode current collector 410, and the negative electrode terminal 301 in the first direction (X direction) of the electrode body 200. As a result, the occupied volumes of the negative electrode plates and positive electrode plates of the electrode body 200 can be increased, and the energy density of the secondary battery 1 can be improved.

[0112] A secondary battery according to a modified example of the embodiment will be described below. The secondary battery according to this modified example has a case structure different from that of the secondary battery 1 according to the embodiment of the present technology, and therefore the description of the same configuration as that of the secondary battery 1 according to the embodiment of the present technology will not be repeated.

[0113] Fig. 18 is a perspective view showing a joined state between a case main body and a first sealing plate included in a secondary battery according to a first modification of an embodiment, in which configurations other than the case are omitted.

[0114] 18, a secondary battery 1A according to a first modification of an embodiment includes a case 100A. The case 100A includes a case main body 110A and a first sealing plate 120A.

[0115] The first sealing plate 120A has a covering portion 126A that covers the end portion on the first side of the case body 110A from the first direction (X direction). The covering portion 126A and the case body 110A are joined by welding.

[0116] A joint 116A is formed between covering portion 126A and outer peripheral surface 111A of case body 110A. Because joint 116A is located on outer peripheral surface 111A of case body 110A, it can be disposed at a location farther away from the insulating member provided between the negative terminal and the first sealing plate, compared to a case in which the entire first sealing plate is inserted into the inner peripheral surface of the case body and a joint is formed between the outer peripheral surface of the first sealing plate and the inner peripheral surface of the case body.

[0117] The joint 116A can be joined by irradiating an energy beam from the outer circumferential surface 111A side of the case body 110A (DR1 direction in FIG. 18). The joint 116A in this embodiment is formed by laser welding, for example. In this case, even if the laser passes through the joint between the covering portion 126A and the case body 110A, the laser can be received by a portion of the first sealing plate 120A that is bent from the covering portion 126A in the first direction (X direction). This makes it possible to prevent the laser from slipping out during laser welding. Note that, although FIG. 18 shows the configuration of the negative electrode side, the same structure as the negative electrode side can also be configured for the positive electrode side.

[0118] In the secondary battery 1A according to the modified embodiment of the present technology, when the case body 110A and the first sealing plate 120A are joined by laser welding or the like, the covering portion 126A located on the outer periphery of the first sealing plate 120A is joined to the outer periphery surface 111A of the case body 110A. This allows the case body 110A and the first sealing plate 120A to be joined in a state where the joining portion between the first sealing plate 120A and the case body 110A is as far away as possible from the resin insulating member provided between the negative terminal 301 and the first sealing plate 120A. As a result, the thermal influence of the joining portion 116A on the insulating member during joining can be suppressed, and deformation of the insulating member can be suppressed, thereby improving the reliability of the secondary battery. The same effect can be achieved on the positive electrode side by making the configuration similar to that of the negative electrode side.

[0119] Fig. 19 is a partial cross-sectional view showing a configuration of a secondary battery according to a second modified example of an embodiment. As shown in Fig. 19, a secondary battery 1B according to a second modified example of an embodiment includes a case 100 and an electrode body 200B. A negative electrode tab group 220B in the electrode body 200B has a base portion 221B, a first curved portion 222B, and a first tip side region 223B.

[0120] The root portion 221B is a portion of the negative electrode tab group 220B that is adjacent to the negative electrode plate. In the root portion 221B, a plurality of negative electrode tabs extending from the negative electrode plate to the end of the first side (first sealing plate 120 side) in the first direction (X direction) are bundled toward the end of the first side.

[0121] The first curved portion 222B is formed by bundling and stacking a plurality of negative electrode tabs. The first curved portion 222B of this modification has gaps between the plurality of negative electrode tabs from the end on the base portion 221B side to the curved portion.

[0122] The first tip side region 223B is a region of the negative electrode tab group 220B that is located closer to the tip side than the first curved portion 222B. Note that, although the connection structure on the negative electrode side of the secondary battery has been described in this modified example, the connection structure on the positive electrode side is similar to that on the negative electrode side.

[0123] In the secondary battery 1B according to the second modified example of the embodiment of the present technology, similarly to the embodiment, the first curved portion 222B of the negative electrode tab group 220B of the electrode body 200B and the center C1 of the first through hole 123 through which the negative electrode terminal 301 is inserted are arranged so as not to overlap in the first direction (X direction). This allows the first curved portion 222B and the negative electrode terminal 301 to be configured not to interfere with each other in the first direction (X direction). Therefore, compared to the case in which the first curved portion 222B and the negative electrode terminal 301 arranged in the first through hole 123 are arranged so as to overlap in the first direction (X direction), the width of the negative electrode tab group 220B and the negative electrode terminal 301 in the first direction (X direction) can be narrowed. As a result, the volume of the negative electrode plate and the positive electrode plate of the electrode body 200B in the case 100 can be increased, and the energy density of the secondary battery 1B can be improved. The same effect can be achieved on the positive electrode side by configuring it in the same way as on the negative electrode side.

[0124] Although the embodiment of the present technology has been described above, the embodiment disclosed herein should be considered as 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 scope and meaning equivalent to the claims. [Explanation of symbols]

[0125] 1, 1A, 1B secondary battery, 100, 100A case, 110, 110A case body, 111A outer peripheral surface, 113 first opening, 114 second opening, 115, 116A, 433, 434, 441, 454 joint, 120, 120A first sealing plate, 121 first end, 122 second end, 123 first through hole, 124, 134 liquid injection hole, 125, 135 gas exhaust valve, 126A coating portion, 130 second sealing plate, 131 third end, 132 fourth end, 133 second through hole, 200, 200B, 201, 202 electrode body, 210 negative electrode plate, 210S negative electrode base plate, 211 negative electrode core, 212 Negative electrode active material layer, 220, 220B Negative electrode tab group, 221, 221B, 251 Base portion, 222, 222B First curved portion, 223, 223B First tip side region, 230 Negative electrode tab, 240 Positive electrode plate, 240S Positive electrode original plate, 241 Positive electrode core, 242 Positive electrode active material layer, 243 Positive electrode protective layer, 250 Positive electrode tab group, 252 Second curved portion, 253 Second tip side region, 260 Positive electrode tab, 300 Electrode terminal, 301 Negative electrode terminal, 302 Positive electrode terminal, 400 Current collector, 410 Negative electrode current collector, 420 Positive electrode current collector, 430 First conductive member, 431 First region, 432 Second region, 435 Step portion, 440 Second conductive member, 510 First insulating member, 520 second insulating member, 600 spacer, 610 first spacer, 620 second spacer, 630a, 630b engagement portion, 700 insulating sheet, C center, C1, C2 centers.

Claims

1. An electrode assembly including a first electrode and a second electrode having a polarity different from that of the first electrode; A case that accommodates the electrode assembly; a first electrode terminal electrically connected to the first electrode and provided on the case; the electrode body includes a first electrode tab group electrically connected to the first electrode and located at an end of a first side of the electrode body in a first direction, and a second electrode tab group electrically connected to the second electrode and located at an end of a second side opposite to the first side in the first direction, the case includes a case body having a first opening located at an end of the first side in the first direction, and a first sealing plate that seals the first opening, the first sealing plate has a first end and a second end positioned opposite to each other in a second direction perpendicular to the first direction, the first electrode tab group has a first curved portion that is bundled and curved, and a first tip side region that is located on a tip side of the first curved portion, the first electrode tab group is curved at the first curved portion such that a tip side of the first curved portion is directed toward the second end portion, the first tip side region is electrically connected to the first electrode terminal, the first sealing plate is provided with a first through hole through which the first electrode terminal is inserted in the first direction, the first curved portion is located closer to the first end portion than a center of the first sealing plate in the second direction, a center of the first through hole is located closer to the second end than a center of the first sealing plate in the second direction.

2. a second electrode terminal electrically connected to the second electrode and provided on the case; the case includes a second sealing plate, the case body has a second opening located at an end of the second side in the first direction, the second sealing plate seals the second opening, the second sealing plate has a third end and a fourth end positioned opposite to each other in the second direction, the second electrode tab group has a second curved portion that is bundled and curved, and a second distal end region that is located on a distal side of the second curved portion, the second electrode tab group is curved at the second curved portion such that a tip side of the second curved portion is directed toward the second end portion, the second tip side region is electrically connected to the second electrode terminal, the second sealing plate is provided with a second through hole through which the second electrode terminal is inserted in the first direction, the second curved portion is located closer to the third end portion than a center of the second sealing plate in the second direction, The secondary battery according to claim 1 , wherein a center of the second through hole is located closer to the fourth end portion than a center of the second sealing plate in the second direction.

3. The secondary battery according to claim 2 , wherein the first end and the third end are located on the same end side in the second direction.

4. a first current collecting member electrically connecting the first electrode terminal and the first electrode tab group; the first current collecting member includes a first component and a second component, the second component is connected to the first electrode terminal; the first component has a first region connected to the second component and a second region connected to the first electrode tab group, a step portion is provided between the first region and the second region, the step portion causing the first region and the second region to be positioned differently in the first direction; The secondary battery according to claim 1 , wherein the step portion extends along a third direction perpendicular to the first direction and the second direction.

5. The secondary battery according to claim 4 , wherein the second region of the first component is disposed along the first sealing plate.

6. a resin member disposed between the first electrode terminal and the first sealing plate, the first sealing plate further has a covering portion that covers the end portion of the first side of the case body from the first direction, The secondary battery according to claim 1 , wherein the covering portion and the case body are joined by welding.

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