Secondary battery

Abstract

The invention provides a secondary battery. The first sealing plate has, in a second direction orthogonal to the first direction, a first end portion and a second end portion that are located on opposite sides from each other. The negative electrode sheet group has a first curved portion and a first tip-side region located further toward the tip side than the first curved portion. The negative electrode sheet group is bent at the first bent portion so as to be closer to the front end side than the first bent portion toward the second end portion side. The first tip-side region is electrically connected to the negative electrode terminal. The first sealing plate is provided with a first through hole through which the negative electrode terminal is inserted in the first direction. The first bent portion is positioned closer to the first end portion side than the center of the first sealing plate in the second direction. The center of the first through hole is located closer to the second end side than the center of the first sealing plate in the second direction.

Description

Technical Field The present technology relates to a secondary battery. Background Art As a prior art document that discloses the structure of a secondary battery, there is Japanese Patent Gazette No. 4537353. The secondary battery described in Japanese Patent Gazette No. 4537353 includes an electrode group, a shell, and a collector. The electrode group is built into the shell. The electrode group includes a positive electrode and a negative electrode having a patternless portion that is not coated with an active material. The patternless portions of the positive electrode and the negative electrode are arranged at respective ends of the wound electrode group in the axial direction of the winding. The collector includes a patternless portion contact portion and a flange portion. The patternless portion contact portion is engaged and connected with the patternless portion. The flange portion is combined with the electrode terminal to support the electrode terminal. In the secondary battery disclosed in Japanese Patent No. 4537353, since the contact part of the non-patterned part and the flange part are arranged in the winding axis of the electrode group, the width occupied by the current collector part for connecting the electrode group and the electrode terminal in the winding axis becomes larger. Therefore, it is impossible to ensure a large occupied volume of the electrode body in the battery case, and it is difficult to increase the energy density of the secondary battery. Even when an electrode sheet group 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 increase, so there is room for improving the energy density of the secondary battery. Summary of the invention The present technology has been made to solve the above-mentioned problems, and an object of the present technology is to provide a secondary battery capable of improving energy density. The present technology provides the following secondary batteries.

[0001] A secondary battery, comprising: an electrode body including a first electrode and a second electrode having a polarity different from that of the first electrode; a shell that accommodates the electrode body; and a first electrode terminal, which is electrically connected to the first electrode and is disposed on the housing; The electrode body comprises: a first electrode sheet group electrically connected to the first electrode and located at an end of the electrode body on a first side in a first direction; and a second electrode sheet group, the second electrode sheet group being electrically connected to the second electrode and being located at an end portion of a second side opposite to the first side in the first direction, The housing comprises: a housing body having a first opening located at an end portion on the first side in the first direction; and a first sealing plate for sealing the first opening; The first sealing plate has a first end and a second end located on opposite sides to each other in a second direction orthogonal to the first direction. The first electrode sheet group includes a first bent portion that is bundled and bent, and a first front end region that is located closer to the front end side than the first bent portion. The first electrode sheet group is bent at the first bent portion so that a portion closer to the front end side than the first bent portion is directed toward the side where the second end portion is located. The first front end 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 bent portion is located closer to the first end portion than the center of the first sealing plate in the second direction. The center of the first through hole is located closer to the second end than the center of the first sealing plate in the second direction.

[0002] In the secondary battery described in [1], The secondary battery further comprises a second electrode terminal electrically connected to the second electrode and provided on the casing. The housing includes a second sealing plate. The housing body has a second opening located at an end portion on 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 located on opposite sides to each other in the second direction. The second electrode sheet group includes a second bent portion that is bundled and bent, and a second front end region that is located closer to the front end side than the second bent portion. The second electrode sheet group is bent at the second bent portion so that a portion closer to the front end side than the second bent portion is directed toward the side where the second end portion is located. The second front end 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 bent portion is located closer to the third end portion than the center of the second sealing plate in the second direction. The center of the second through hole is located closer to the fourth end portion than the center of the second sealing plate in the second direction.

[0003] In the secondary battery described in [2], In the second direction, the first end portion and the third end portion are located on the same end portion side.

[0004] In the secondary battery described in any one of [1] to [3], The secondary battery further comprises a first current collecting member electrically connecting the first electrode terminal to the first electrode sheet group. The first current collecting member comprises a first member and a second member. 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 sheet group. A step portion is provided between the first region and the second region so that the positions of the first region and the second region in the first direction are different. The step portion extends along a third direction that is orthogonal to the first direction and the second direction.

[0005] In the secondary battery described in [4], The second region of the first member is arranged along the first sealing plate.

[0006] In the secondary battery described in any one of [1] to [5], The secondary battery further comprises a resin member disposed between the first electrode terminal and the first sealing plate. The first sealing plate further includes a covering portion that covers the first side end portion of the housing body from the first direction. The covering portion and the housing body are joined by welding. The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 This is a front view showing the structure of a secondary battery according to one embodiment of the present technology. Figure 2 It means observing from the direction of arrow II Figure 1 A diagram showing the state of a secondary battery. Figure 3 It means observing from the direction of arrow III Figure 1 A diagram showing the state of a secondary battery. Figure 4 It means observing from the direction of arrow IV Figure 1 A diagram showing the state of a secondary battery. Figure 5 yes Figure 1 A front cross-sectional view of a secondary battery is shown. Figure 6 It is a front view showing a negative electrode original plate before forming a negative electrode plate. Figure 7 yes Figure 6 VII-VII cross-sectional view of the negative electrode original plate shown. Figure 8 It is a front view showing a negative electrode plate formed from a negative electrode original plate. Fig. 9 It is a front view showing a positive electrode original plate before forming a positive electrode plate. Fig.10 yes Fig. 9 XX cross-sectional view of the positive electrode original plate shown. Fig.11 It is a front view showing a positive electrode plate formed from a positive electrode original plate. Fig.12 It is a diagram showing an electrode body and a current collector taken out from a secondary battery. Fig.13 It is a front view of the connection structure between the negative electrode sheet group and the negative electrode collector. Fig.14 It is a cross-sectional view of the connection structure between the negative electrode sheet group and the negative electrode current collector. Fig.15 It is a diagram showing the step of inserting the electrode body into the case body. Fig.16 It is a diagram showing a step of placing a separator between a sealing plate and an electrode body. Fig.17 This is a partial cross-sectional view of a secondary battery according to one embodiment as viewed from the top surface. Fig.18 It is a perspective view showing a joined state of a case body and a first sealing plate included in a secondary battery according to a first modification of one embodiment. Fig.19 It is a partial cross-sectional view showing the structure of a secondary battery according to a second modification of one embodiment. DETAILED DESCRIPTION Hereinafter, embodiments of the present technology will be described. In addition, the same reference numerals are given to the same or corresponding parts, and the description thereof may not be repeated. In addition, in the embodiments described below, when the number, amount, etc. are mentioned, the scope of the present technology is not necessarily limited to the number, amount, etc., unless otherwise specified. In addition, in the following embodiments, except for the cases where there are special records, each component is not necessarily essential to the present technology. In addition, the present technology is not necessarily limited to the technology that has all the effects mentioned in the present embodiment. In addition, in this specification, the descriptions of "comprise", "include", and "have" are open forms. That is, when a certain structure is included, other structures other than the structure may or may not be included. In addition, in this specification, when geometrical terms and terms indicating position and direction relationships are used, such as "parallel", "orthogonal", "oblique 45 degrees", "coaxial", "along", etc., these terms allow for manufacturing errors or some changes. In this specification, when terms such as "upper side" and "lower side" are used to indicate relative positional relationships, these terms are used to indicate relative positional relationships in one state, and the relative positional relationship can be reversed or rotated to any angle depending on the installation direction of each mechanism (for example, turning the entire mechanism upside down, etc.). In this specification, "secondary battery" is not limited to lithium-ion batteries, and may include other secondary batteries such as nickel-hydrogen batteries and sodium-ion batteries. In this specification, "electrode" may be collectively referred to as positive electrode and negative electrode. In addition, in the drawings, the direction along the winding axis of the electrode body of the secondary battery is set as the X direction as the first direction, the short side direction of the electrode body perpendicular to the first direction and observed from the first direction is set as the Y direction as the second direction, and the long side direction of the electrode body perpendicular to the first direction and observed from the first direction is set as the Z direction as the third direction. In addition, in order to facilitate the understanding of the invention, there are parts in which the dimensions of each structure in the drawings are changed from the actual dimensions. In the present application specification, the first direction (X direction) is sometimes referred to as the “width direction” of the secondary battery or the shell body, the second direction (Y direction) is similarly referred to as the “thickness direction” of the secondary battery or the shell body, and the third direction (Z direction) is similarly referred to as the “height direction” of the secondary battery or the shell body. (Overall structure of the battery) Figure 1 It is a front view of the secondary battery 1 of this embodiment. Figure 2 to Figure 4 They are respectively viewed from the direction of arrow II, arrow III, and arrow IV. Figure 1 The diagram shows the state of the secondary battery 1. Figure 5 yes Figure 1 The secondary battery 1 is shown in front cross-sectional view. The secondary battery 1 can be mounted on an electric vehicle (BEV), a plug-in hybrid electric vehicle (PHEV), a hybrid electric vehicle (HEV), etc. However, the use of the secondary battery 1 is not limited to vehicle-mounted use. like Figure 1 to Figure 5 As shown, 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 body 110 , a first sealing plate 120 , and a second sealing plate 130 . When forming a battery pack including secondary batteries 1, a plurality of 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 constraining member to form a battery module, or the battery pack may be directly supported on the side of the battery pack housing without using a constraining member. The case body 110 is formed of a cylindrical, preferably rectangular, member. This provides a rectangular secondary battery 1. The case body 110 is made of metal. Specifically, the case body 110 is made of aluminum, aluminum alloy, iron, or iron alloy. like Figure 1 , Figure 2 As shown in FIG. 1 , a first sealing plate 120 and a second sealing plate 130 are provided at both ends of the housing body. The housing body 110 is formed by, for example, bringing the ends of the plate-like members subjected to bending into contact with each other (at Figure 2 The square tube shape can be formed by joining the two members (for example, laser welding) to each other as shown in the joining portion 115 illustrated in FIG. The corners of the "square tube shape" may also have an R shape. In the present embodiment, the shell body 110 is formed in the width direction (X direction) of the secondary battery 1 to be longer than the thickness direction (Y direction) and the height direction (Z direction) of the secondary battery 1. The dimension (width) of the shell body 110 in the X direction is preferably more than 30 cm. Thus, a relatively large (high capacity) secondary battery 1 can be formed. The dimension (height) of the shell body 110 in the Z direction is preferably less than 20 cm, more preferably less than 15 cm, and further preferably less than 10 cm. Thus, a secondary battery 1 with a relatively low height (low height) can be formed, for example, the mountability on a vehicle is improved. like Figure 3 As shown, a first opening 113 is provided at the end of the first side in the first direction (X direction) of the housing body 110. The first opening 113 is sealed by a first sealing plate 120. The first opening 113 and the first sealing plate 120 have a substantially rectangular shape with the Y direction being the short side direction and the Z direction being the long side direction. The first sealing plate 120 has a first end 121 and a second end 122 located on opposite sides of each other in the second direction (Y direction). The first sealing plate 120 is provided with a negative electrode terminal 301 (first electrode terminal), a liquid injection hole 124, and a gas exhaust valve 125. The positions of the negative electrode terminal 301, the liquid injection hole 124, and the gas exhaust valve 125 can be changed as appropriate. like Figure 4 As shown, a second opening 114 is provided at the end of the second side in the first direction (X direction) of the housing body 110. 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 being the short side direction and the Z direction being the long side direction. The second sealing plate 130 has a third end 131 and a fourth end 132 located on opposite sides of each other in the second direction. The second sealing plate 130 is provided with a positive electrode terminal 302 (second electrode terminal), a liquid injection hole 134, and a gas exhaust valve 135. The positions of the positive electrode terminal 302, the liquid injection hole 134, and the gas exhaust valve 135 can be changed as appropriate. like Figure 3 and Figure 4 As shown, 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. In addition, 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. 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, aluminum alloy, iron, iron alloy, or the like. 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 . 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 , that is, the outer surface of the case 100 . The negative electrode terminal 301 is made of a conductive material (more specifically, a metal), for example, copper or a copper alloy, etc. A portion or layer made of aluminum or an aluminum alloy may be provided on the outer surface of the negative electrode terminal 301 . The positive electrode terminal 302 is made of a conductive material (more specifically, a metal), and can be made of, for example, aluminum or an aluminum alloy. The injection holes 124 and 134 are sealed by a sealing member (not shown). As the sealing member, for example, a blind rivet or other metal member can be used. The exhaust valves 125 and 135 break when the pressure in the housing 100 reaches a predetermined value or more, and exhaust the gas in the housing 100 to the outside. The electrode body 200 is a flat electrode body having a positive electrode plate and a negative electrode plate described later. Specifically, the electrode body 200 is a wound electrode body formed by winding a strip-shaped positive electrode plate and a strip-shaped negative electrode plate together via a strip-shaped separator not shown. However, in this specification, the "electrode body" is not limited to a wound electrode body, and may also be a stacked electrode body formed by alternately stacking a plurality of positive plates and a plurality of negative plates. The electrode body includes a plurality of positive plates and a plurality of negative plates, and the positive electrode sheets provided on each positive plate may also be stacked to form a positive electrode sheet group, and the negative electrode sheets provided on each negative plate may also be stacked to form a negative electrode sheet group. like Figure 5 As shown, the case 100 accommodates the electrode body 200. The electrode body 200 is accommodated in the case 100 so that the winding axis thereof is parallel to the X direction. Specifically, a single or a plurality of wound electrode bodies and an electrolyte (electrolyte) not shown are housed together inside an insulating sheet 700 to be described later and arranged in the housing 100. As the electrolyte (non-aqueous electrolyte), for example, an electrolyte obtained by dissolving LiPF6 at a concentration of 1.2 mol / L in a non-aqueous solvent obtained by mixing ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC) in a volume ratio (25° C.) of 30:30:40 can be used. In addition, a solid electrolyte may be used instead of the electrolyte. The electrode body 200 includes a negative electrode sheet group 220 (first electrode sheet group) and a positive electrode sheet group 250 (second electrode sheet group). The negative electrode sheet group 220 is located at the end of the first side of the electrode body 200 in the first direction (X direction). The first side in this embodiment is the side where the first sealing plate 120 is located. The positive electrode sheet group 250 is located at the end of the second side on the opposite side of the first side in the first direction (X direction). The second side in this embodiment is the side where the second sealing plate 130 is located. The negative electrode sheet group 220 and the positive electrode sheet group 250 are formed to protrude from the center of the electrode body 200 toward the first sealing plate 120 or the second sealing plate 130. The protruding manner of the negative electrode sheet group 220 and the positive electrode sheet group 250 is not limited to this manner. 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 respectively composed of plate-like components. The electrode body 200 is electrically connected to the negative terminal 301 and the positive terminal 302 via the current collector 400. In addition, the negative electrode sheet group 220 can also be directly connected to the negative terminal 301. It is also possible to directly connect the positive electrode sheet group 250 to the positive terminal 302. 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 sheet group 220 and the negative electrode terminal 301. The negative electrode current collector 410 is made of a conductive material (more specifically, metal), such as copper or a copper alloy. The positive electrode collector 420 is disposed on the second sealing plate 130 via a resin insulating member. The positive electrode collector 420 is electrically connected to the positive electrode sheet group 250 and the positive electrode terminal 302. The positive electrode collector 420 is made of a conductive material (more specifically, metal), such as aluminum or an aluminum alloy. (Structure of Electrode Body 200) Figure 6 2 is a front view showing a negative electrode original plate 210S before forming a negative electrode plate 210 (first electrode). Figure 7 yes Figure 6 The VII-VII cross-sectional view of the negative electrode original plate 210S shown in FIG. Figure 8 1 is a front view showing a negative electrode plate 210 formed from a negative electrode original plate 210S. The negative electrode plate 210 is manufactured by processing the negative electrode original plate 210S. Figure 6 and Figure 7 As shown, 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. The negative electrode core 211 has a negative electrode active material layer 212 formed thereon except for one end portion of both surfaces. The negative electrode active material layer 212 is formed by applying a negative electrode active material layer slurry using a die coater. The negative electrode active material layer slurry is prepared by kneading graphite as a 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 about 98:1:1. The negative electrode core 211 coated with the negative electrode active material layer slurry is dried to remove the water contained in the negative electrode active material layer slurry, thereby forming the negative electrode active material layer 212. Furthermore, the negative electrode original plate 210S including the negative electrode core 211 and the negative electrode active material layer 212 is formed by compressing 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 based on energy line irradiation, metal mold processing, or tool processing. like Figure 8As shown, at one end in the width direction of the negative electrode plate 210 formed by the negative electrode original plate 210S, a plurality of negative electrode sheets 230 formed by the negative electrode core 211 are provided. When the negative electrode plate 210 is wound, the plurality of negative electrode sheets 230 are stacked to form a negative electrode sheet group 220. As a result, the negative electrode sheet group 220 is connected to the negative electrode plate 210 (first electrode). The positions of the respective plurality of negative electrode sheets 230 and the lengths in the protruding direction are appropriately adjusted in consideration of the connection state between the negative electrode sheet group 220 and the negative electrode collector 410. In addition, the shape of the negative electrode sheet 230 is not limited to Figure 8 The shape illustrated in . Fig. 9 2 is a front view showing a positive electrode original plate 240S before forming a positive electrode plate 240 (second electrode). Fig.10 yes Fig. 9 The XX-sectional view of the positive electrode original plate 240S shown in FIG. Fig.11 1 is a front view showing a positive electrode plate 240 formed of a positive electrode original plate 240S. The positive electrode plate 240 as the second electrode has a different polarity from the negative electrode plate 210 as the first electrode. The positive electrode plate 240 is manufactured by processing a positive electrode original plate 240S. Fig. 9 and Fig.10 As shown, the positive electrode original plate 240S 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 core body 241 has a positive electrode active material layer 242 formed thereon except for one end portion of both surfaces. The positive electrode active material layer 242 is formed on the positive electrode core body 241 by applying a positive electrode active material layer slurry using a die coater. The positive electrode active material layer slurry is prepared by kneading lithium nickel cobalt manganese composite oxide as a positive electrode active material, polyvinylidene fluoride (PVdF) as a binding material, a carbon material as a conductive material, and N-methyl-2-pyrrolidone (NMP) as a dispersion medium in such a manner that the mass ratio of lithium nickel cobalt manganese composite oxide:PVdF:carbon material becomes approximately 97.5:1:1.5. The positive electrode protection layer 243 is in contact with the positive electrode core 241 and is formed at one end of the positive electrode active material layer 242 in the width direction. The positive electrode protection layer 243 is formed on the positive electrode core 241 by applying the positive electrode protection layer slurry using a die coater. The positive electrode protection layer 243 has a resistance greater than that of the positive electrode active material layer 242. The positive electrode protective layer slurry was 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 was about 83:3:14. The positive electrode core 241 coated with the positive electrode active material layer slurry and the positive electrode protective layer slurry is dried to remove the NMP contained in the positive electrode active material layer slurry and the positive electrode protective layer slurry, thereby forming the positive electrode active material layer 242 and the positive electrode protective layer 243. Furthermore, by compressing the positive electrode active material layer 242, 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 is formed. The positive electrode original plate 240S is formed by cutting the positive electrode original plate 240S into a predetermined shape. The positive electrode original plate 240S can be cut by laser processing based on energy line irradiation, metal mold processing, or tool processing. like Fig.11 As shown, at one end portion in the width direction of the positive electrode plate 240 formed by the positive electrode original plate 240S, a plurality of positive electrode sheets 260 formed by the positive electrode core 241 are provided. When the positive electrode plate 240 is wound, the plurality of positive electrode sheets 260 are stacked to form a positive electrode sheet group 250. Thus, the positive electrode sheet group 250 is in a state of being connected to the positive electrode plate 240 (the second electrode). The positions of the respective plurality of positive electrode sheets 260 and the lengths in the protruding direction are appropriately adjusted in consideration of the state in which the positive electrode sheet group 250 is connected to the positive electrode collector 420. In addition, the shape of the positive electrode sheet 260 is not limited to Fig.11 The shape illustrated in . The positive electrode protection layer 243 is provided at the root of each of the plurality of positive electrode sheets 260. The positive electrode protection layer 243 does not necessarily need to be provided at the root of the positive electrode sheet 260. In a typical example, the thickness of the negative electrode sheet 230 (one sheet) is smaller than the thickness of the positive electrode sheet 260 (one sheet). In this case, the thickness of the negative electrode sheet group 220 is smaller than the thickness of the positive electrode sheet group 250. (Connection Structure of Electrode Body 200 and Current Collector 400) Fig.12 FIG. 2 is a diagram showing an electrode body 200 and a current collector 400 taken out of a secondary battery 1. Fig.12 As shown in FIG. 1 , the electrode body 200 is formed by stacking two electrode bodies 201 and 202, each of which is a wound electrode body. Fig.12 In the example shown, a structure in which two wound electrode bodies are stacked is shown, but the electrode body 200 may be composed of one wound electrode body, three or more wound electrode bodies, or a stacked electrode body. The negative electrode sheet group 220 is joined to the negative electrode current collector 410 at the joining portion 434 , and the positive electrode sheet group 250 is joined to the positive electrode current collector 420 at the joining portion 454 . Fig.13 It is a front view of the connection structure between the negative electrode sheet group and the negative electrode collector. Fig.14 It is a cross-sectional view of the connection structure between the negative electrode sheet group and the negative electrode current collector. like Fig.13 and Fig.14 As shown, the negative electrode current collector 410 electrically connects the negative electrode terminal 301 and the negative electrode sheet 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. The negative electrode current collector 410 includes a first conductive member 430 (first member) and a second conductive member 440 (second member). The first conductive member 430 and the second conductive member 440 are joined at a joining portion 433. The first conductive member 430 and the second conductive member 440 are joined by, for example, laser welding. The first conductive member 430 is bonded to the negative electrode sheet group 220 at the bonding portion 434. The bonding portion 434 can be formed by, for example, ultrasonic welding, resistance welding, laser welding, riveting, etc. In the present embodiment, the first conductive member 430 and the negative electrode sheet group 220 are bonded by, for example, ultrasonic bonding. The second conductive member 440 is connected to the negative terminal 301 at the joint 441. The joint 441 can be formed, for example, by ultrasonic welding, resistance welding, laser welding, riveting, etc. In the present embodiment, the negative terminal 301 and the second conductive member 440 are joined by, for example, providing a through hole in the second conductive member 440, inserting the negative terminal 301 into the through hole, riveting the negative terminal 301 to the second conductive member 440, and then welding the riveted portion and the second conductive member 440. The first conductive member 430 includes 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 sheet group 220. The second region 432 is disposed along the first sealing plate 120. A step portion 435 is provided between the first region 431 and the second region 432. With respect to the step portion 435, the first region 431 and the second region 432 are positioned differently in the first direction (X direction) when the secondary battery 1 is assembled. Thus, the first region 431 and the second region 432 can be arranged in one direction. The step portion 435 extends along the third direction (Z direction). 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. In addition, the first insulating member 510 and the second insulating member 520 may be an integral member. The negative electrode terminal 301 is attached to the first sealing plate 120 via the first insulating member 510 . The negative electrode terminal 301 is exposed outside the first sealing plate 120 and reaches the second conductive member 440 of the negative electrode collector 410 provided on the inner surface of the first sealing plate 120 . As the assembly order of each component, first, the negative terminal 301 and the second conductive component 440 are mounted on the first sealing plate 120 together with the first insulating component 510 and the second insulating component 520. Next, the first conductive component 430 electrically connected to the electrode body 200 is mounted on the second conductive component 440. At this time, the first conductive component 430 is arranged on the first insulating component 510 in such a manner that a part of the first conductive component 430 overlaps with the second conductive component 440. Next, the first conductive component 430 and the second conductive component 440 are welded and connected at the joint 434. The negative electrode terminal 301 may be electrically connected to the first sealing plate 120 . In addition, the first sealing plate 120 may also play the role of the negative electrode terminal 301 . In addition, Fig.13 and Fig.14 In FIG. 4 , the negative electrode current collector 410 is exemplified as being composed of two members (the first conductive member 430 and the second conductive member 440 ), but the negative electrode current collector 410 may be composed of a single member. exist Fig.13 and Fig.14 , the connection structure on the negative electrode side is shown, but the basic connection structure on the positive electrode side is also the same as that on the negative electrode side. (Step of Inserting Electrode Body 200) Fig.15 2 is a diagram showing the process of inserting the electrode body 200 into the case body 110. Fig.15 As shown, a resin insulating sheet 700 (electrode body holder) is arranged between the electrode body 200 and the case body 110 . The insulating sheet 700 may be made of, for example, resin. More specifically, the insulating sheet 700 may be made of, for example, polypropylene (PP), polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polyimide (PI), or polyolefin (PO). The insulating sheet 700 does not necessarily need to cover the entire surface of the electrode body 200. The insulating sheet 700 preferably covers 50% or more of the outer surface of the electrode body, and more preferably covers 70% or more of the area. The insulating sheet 700 preferably covers the entirety of four of the six surfaces of the substantially rectangular parallelepiped (flat) electrode body 200, except for at least two surfaces each having the negative electrode sheet group 220 and the positive electrode sheet group 250 formed thereon. The first sealing plate 120, the negative electrode terminal 301, and the negative electrode sheet group 220 are joined before the electrode body 200 is inserted into the case body 110. The second sealing plate 130, the positive electrode terminal 302, and the positive electrode sheet group 250 are joined after the electrode body 200 is inserted into the case body 110. Fig.16 This is a diagram showing a step of placing the separator 600 between the first sealing plate 120 and the electrode body 200 . like Fig.16 As shown, the negative electrode sheet group 220 arranged from the electrode body 200 toward the first sealing plate 120 is bent from the center of the first sealing plate 120 in the Y direction toward the end, and then folded back toward the center. The separator 600 is provided in a manner to accommodate the bent portion of the negative electrode sheet group 220. The structure of the negative electrode sheet group 220 will be described in detail later. 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 means of the engaging portions 630a and 630b by sliding along the Y direction from the end side toward the center side of the first sealing plate 120. Thus, the spacer 600 is fixed to the first sealing plate 120 via the first insulating member 510, and the stability of the position of the spacer 600 is increased. (Joining Structure of Electrode Body 200 and Electrode Terminal 300) Fig.17 This is a partial cross-sectional view of a secondary battery according to one embodiment as viewed from the top surface. Fig.17 As shown, the negative electrode sheet group 220 in the electrode body 200 includes a root portion 221 , a first bent portion 222 , and a first front end region 223 . The root portion 221 is a portion adjacent to the negative electrode plate in the negative electrode sheet group 220. In the root portion 221, a plurality of negative electrode sheets extending from the negative electrode plate to the end portion on the first side (the side where the first sealing plate 120 is located) in the first direction (X direction) are bundled as they move toward the end portion on the first side. A plurality of negative electrode sheets are bundled and stacked in the first bent portion 222. The first bent portion 222 is connected to the root portion 221 at an end portion on the first side in the first direction (X direction) of the root portion 221. The negative electrode sheet group 220 is bent at the first bent portion 222 so that the portion closer to the front end side than the first bent portion 222 is bent in the second direction (Y direction) toward the second end portion 122 side. The first bent portion 222 is bundled and bent so as to be folded back toward the opposite side in the second direction (Y direction). The first bent portion 222 in this embodiment is bent from the root portion 221 to the first end portion 121 side in the second direction (Y direction), and then folded back to the second end portion 122 side to be bundled. The first bent 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). In addition, the first bent portion 222 in the present embodiment includes a portion that is bundled and extends linearly in the second direction (Y direction) and is located on the first end 121 side of the center C of the first sealing plate 120, but is not limited to this structure. The first bent portion 222 may also be a structure in which at least only the bent portion is located on the first end 121 side of the center C of the first sealing plate 120. The first front end region 223 is a region of the negative electrode sheet group 220 located closer to the front end than the first bent portion 222. In this embodiment, the first front end region 223 is electrically connected to the negative electrode terminal 301 via the negative electrode collector 410. The first front end region 223 is bonded to the first conductive member 430 in the negative electrode collector 410. The first sealing plate 120 is provided with a first through hole 123 for the negative terminal 301 to be inserted in the 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). In addition, the 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 as a whole, but is not limited to this structure. The first through hole 123 may also be: 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, and a part of the opening of the hole is located on the first end 121 side of the center C of the first sealing plate 120. The first through hole 123 is preferably in a perfect circular shape. However, the first through hole 123 may also be in a square, an ellipse, a racetrack shape, etc. When formed in these shapes, the center C1 of the first through hole 123 is the center of gravity when viewed from the first direction (X direction). Since the center C1 of the first through hole 123 is located closer to the second end 122 than the center C of the first sealing plate 120 in the second direction (Y direction), the central axis of the negative terminal 301 arranged inside the first through hole 123 is also located closer to the second end 122 than the center C of the first sealing plate 120 in the second direction (Y direction). As a result, the negative terminal 301 and the first bent portion 222 of the negative electrode sheet group 220 are arranged so as not to overlap in the first direction (X direction). In addition, the first bent portion 222 may be arranged to overlap with the portion of the negative terminal 301 that is joined to the negative electrode collector 410 in the second direction (Y direction) according to the degree of curvature of the negative electrode sheet group 220. In addition, the negative terminal 301 may be configured so that it does not necessarily extend from the first through hole 123 along the first direction (X direction) at the portion located on the outer surface of the first sealing plate 120. The positive electrode sheet group 250 in the electrode assembly 200 includes a root portion 251 , a second bent portion 252 , and a second front end region 253 . The root portion 251 is a portion adjacent to the positive electrode plate in the positive electrode sheet group 250. In the root portion 251, a plurality of positive electrode sheets extending from the second electrode to the end portion on the second side (the side where the second sealing plate 130 is located) in the first direction are bundled toward the end portion on the second side. A plurality of positive electrode sheets are bundled and stacked in the second bent portion 252. The second bent portion 252 is connected to the root portion 251 at the end portion on the second side of the root portion 251 in the first direction (X direction). The positive electrode sheet group 250 is bent at the second bent portion 252 so that the portion closer to the front end side than the second bent portion 252 is bent in the second direction (Y direction) toward the fourth end portion 132 side. The second bent portion 252 is bundled and bent so as to be folded back toward the opposite side in the second direction (Y direction). The second bent portion 252 in this embodiment is bent from the root 251 to the third end portion 131 side in the second direction (Y direction), and then folded back to the fourth end portion 132 side to be bundled. 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). In addition, the second curved portion 252 in this embodiment includes a portion that is bundled and extends linearly in the second direction (Y direction) and is located on the third end 131 side of the center C of the second sealing plate 130, but is not limited to this structure. The second curved portion 252 may also be a structure in which at least only the curved portion is located on the third end 131 side of the center C of the second sealing plate 130. The second front end region 253 is a region of the positive electrode sheet assembly 250 located closer to the front end than the second bent portion 252. In the present embodiment, the second front end region 253 is electrically connected to the positive electrode terminal 302 via the positive electrode current collector 420. In this embodiment, the first curved portion 222 and the second curved portion 252 are bent toward the same side in the second direction (Y direction). Therefore, when the first curved portion 222 and the second curved portion 252 are bent and formed, the bending directions are unified, thereby facilitating the bending process. In addition, the first curved portion 222 and the second curved portion 252 may also be bent toward opposite sides in the second direction (Y direction). The second sealing plate 130 is provided with a second through hole 133 for the positive terminal 302 to be inserted in the first direction (X direction). The center C2 of the second through hole 133 is located on the side of the fourth end 132 relative to the center C of the second sealing plate 130 in the second direction (Y direction). In addition, the opening of the second through hole 133 is located on the side of the fourth end 132 relative to the center C of the second sealing plate 130 as a whole, but is not limited to this structure. The second through hole 133 may also be configured such that the center C2 of the second through hole 133 is located on the side of the fourth end 132 relative to the center C of the second sealing plate 130, and a portion of the opening of the hole is located on the side of the third end 131 relative to the center C of the second sealing plate 130. The second through hole 133 is preferably in a perfect circular shape. However, the second through hole 133 may also be in a square, an ellipse, a racetrack shape, etc. When formed in these shapes, the center C2 of the second through hole 133 is the center of gravity when viewed from the first direction (X direction). 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. Therefore, when the first bent portion 222 and the second bent portion 252 are bent toward the same side in the second direction (Y direction), it becomes a structure that is easy to electrically connect them. Since the center C2 of the second through hole 133 is located closer to the fourth end 132 than the center C of the second sealing plate 130 in the second direction (Y direction), the positive terminal 302 arranged inside the second through hole 133 is also located closer to the fourth end 132 than the center C of the second sealing plate 130 in the second direction (Y direction). Thus, the positive terminal 302 and the second bent portion 252 of the positive electrode sheet group 250 are arranged so as not to overlap in the first direction (X direction). In addition, the second bent portion 252 may be arranged to overlap with the portion of the positive terminal 302 joined to the positive current collector 420 in the second direction (Y direction) according to the degree of curvature of the positive electrode sheet group 250. In addition, the positive terminal 302 may be configured so that it does not necessarily extend from the second through hole 133 along the first direction (X direction) at the portion located on the outer surface of the second sealing plate 130. like Fig.17As shown, in a secondary battery 1 of one embodiment, the negative terminal 301 and the first bent portion 222 of the negative electrode sheet group 220 are configured not to overlap in the first direction (X direction). That is, when viewed from the first direction (X direction), the negative terminal 301 and the first bent portion 222 are staggered in the second direction (Y direction). As a result, the negative terminal 301 and the first bent portion 222 can be a structure that is difficult to interfere with each other in the first direction (X direction). Therefore, the occupied width W1 of the first bent portion 222, the negative electrode collector 410, and the negative terminal 301 in the housing 100 in the first direction (X direction) 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 housing 100 can be increased, so the energy density of the secondary battery 1 can be increased. Furthermore, by configuring the first bent portion 222 on the first end portion 121 side, the negative electrode sheet assembly 220 can be easily bent and the first bent portion 222 can be easily formed, compared with a structure in which the first bent portion is configured near the center C in the second direction (Y direction), thereby enabling the secondary battery 1 to be manufactured efficiently. Furthermore, although the connection structure on the negative electrode side of the secondary battery in the present embodiment has been described, the connection structure on the positive electrode side is also the same as that on the negative electrode side. In a secondary battery 1 of an embodiment of the present technology, the first bent portion 222 of the negative electrode sheet group 220 of the electrode body 200 and the center C1 of the first through hole 123 for inserting the negative terminal 301 are configured not to overlap in the first direction (X direction). As a result, the first bent portion 222 and the negative terminal 301 can be made into a structure that does not interfere with each other in the first direction (X direction). Therefore, compared with the case where the first bent portion 222 and the negative terminal 301 arranged in the first through hole 123 are overlapped in the first direction (X direction), the occupied width W1 of the negative electrode sheet group 220 and the negative terminal 301 in the first direction (X direction) can be narrowed. As a result, the occupied volume of the negative plate and the positive plate of the electrode body 200 in the shell 100 can be increased, so the energy density of the secondary battery 1 can be improved. In a secondary battery 1 of an embodiment of the present technology, the second bent portion 252 of the positive electrode sheet group 250 of the electrode body 200 and the center C2 of the second through hole 133 for inserting the positive terminal 302 are configured to be non-overlapping in the first direction (X direction), similar to the structure on the negative electrode side. As a result, the second bent portion 252 and the positive terminal 302 can be made into a structure that is difficult to interfere with each other in the first direction (X direction). Therefore, compared with the case where the second bent portion 252 and the positive terminal 302 arranged in the second through hole 133 are overlapped in the first direction (X direction), the width W1 occupied by the positive electrode sheet group 250 and the positive 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 shell 100 can be increased, so that the energy density of the secondary battery 1 can be improved. In a secondary battery 1 of one embodiment of the present technology, by making the bending directions of the first bent portion 222 forming the negative electrode sheet group 220 and the second bent portion 252 of the positive electrode sheet group 250 the same, the bent portions can be bent stably and easily compared to the case where the first bent portion 222 and the second bent portion 252 are bent to opposite sides, thereby enabling the electrode body 200 to be manufactured efficiently. In the secondary battery 1 of one embodiment of the present technology, by providing a step portion 435 between the first region 431 and the second region 432 of the first conductive component 430 of the negative electrode collector 410, 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 of the first conductive component 430 of the negative electrode collector 410 and the second conductive component 440 can be overlapped in the second direction (Y direction), and the second region 432 of the first conductive component 430 can be arranged closer to the first sealing plate 120. As a result, the occupied width W1 of the negative electrode sheet group 220, the negative electrode collector 410, and the negative terminal 301 in the first direction (X direction) can be made narrower. As a result, the occupied volume of the negative electrode plate and the positive electrode plate of the electrode body 200 in the housing 100 can be increased, so the energy density of the secondary battery 1 can be improved. Furthermore, the positive electrode current collector 420 has the same structure as the negative electrode current collector 410 , and thus the same effects can be achieved. In the secondary battery 1 of one embodiment of the present technology, the second region 432 of the first conductive member 430 of the negative electrode collector 410 is arranged to be opposite to the first sealing plate 120, so that the occupied width W1 of the negative electrode sheet group 220, the negative electrode collector 410, and the negative electrode terminal 301 can be made narrower in the first direction (X direction) of the electrode body 200. As a result, the occupied volume of the negative electrode plate and the positive electrode plate of the electrode body 200 can be increased, so that the energy density of the secondary battery 1 can be improved. A secondary battery according to a modification of one embodiment is described below. The secondary battery according to this modification has a casing structure different from that of the secondary battery 1 according to one embodiment of the present technology, and therefore the same structure as that of the secondary battery 1 according to one embodiment of the present technology will not be described repeatedly. Fig.18 1 is a perspective view showing a joined state of a case body and a first sealing plate included in a secondary battery according to a first modification of an embodiment. Fig.18 In the figure, structures other than the shell are omitted. like Fig.18 As shown, a secondary battery 1A according to a first modification of one embodiment includes a case 100A. The case 100A includes a case body 110A and a first sealing plate 120A. The first sealing plate 120A includes a covering portion 126A that covers the first end portion of the case body 110A from the first direction (X direction). The covering portion 126A and the case body 110A are joined by welding. A joint portion 116A is formed between the covering portion 126A and the outer peripheral surface 111A of the case body 110A. Since the joint portion 116A is located on the outer peripheral surface 111A of the case body 110A, it can be arranged at a location away from the insulating member provided between the negative electrode terminal and the first sealing plate, compared with a case where the first sealing plate is entirely inserted into the inner peripheral surface of the case body and the joint portion is formed between the outer peripheral surface of the first sealing plate and the inner peripheral surface of the case body. The joint portion 116A can be formed, for example, from the outer peripheral surface 111A side (at the Fig.18 The joint 116A in this embodiment is formed by, for example, laser welding. In this case, if the laser passes through the joint between the covering portion 126A and the shell body 110A, the laser can be blocked by the portion of the first sealing plate 120A that is bent from the covering portion 126A and along the first direction (X direction). Therefore, the laser can be prevented from passing through during laser welding. In addition, Fig.18 In FIG. 1 , the structure of the negative electrode side is shown, but the positive electrode side can also have the same structure as that of the negative electrode side. In the secondary battery 1A involved in a modified example of one embodiment of the present technology, when the shell body 110A is joined to the first sealing plate 120A by laser welding or the like, the covering portion 126A located at the outer periphery of the first sealing plate 120A is joined to the outer peripheral surface 111A of the shell body 110A. Thus, the shell body 110A and the first sealing plate 120A can be joined while the joining portion between the first sealing plate 120A and the shell 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 heat effect of the joining portion 116A when joined to the insulating member can be suppressed, and the deformation of the insulating member can be suppressed, so that the reliability of the secondary battery can be improved. In addition, on the positive electrode side, the same effect is achieved by having the same structure as the negative electrode side. Fig.19 FIG. 1 is a partial cross-sectional view showing the structure of a secondary battery according to a second modification of one embodiment. Fig.19 As shown, a secondary battery 1B according to a second modification of one embodiment includes a case 100 and an electrode body 200B. A negative electrode sheet group 220B in the electrode body 200B includes a root portion 221B, a first bent portion 222B, and a first front end region 223B. The root portion 221B is a portion of the negative electrode sheet group 220B adjacent to the negative electrode plate. The plurality of negative electrode sheets extending from the negative electrode plate to the end portion on the first side (the first sealing plate 120 side) of the root portion 221B in the first direction (X direction) are bundled toward the end portion on the first side. The first bent portion 222B is a portion where a plurality of negative electrode sheets are bundled and stacked. The first bent portion 222B of this modification has gaps between the plurality of negative electrode sheets between the end portion on the root 221B side and the bent portion. The first front end region 223B is a region of the negative electrode sheet group 220B located closer to the front end than the first bent portion 222B. In this modification, the connection structure of the negative electrode side of the secondary battery is described, but the connection structure of the positive electrode side is the same as that of the negative electrode side. In the secondary battery 1B involved in the second variant of one embodiment of the present technology, the first bent portion 222B of the negative electrode sheet 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 configured to not overlap in the first direction (X direction) as in the first embodiment. As a result, the first bent portion 222B and the negative electrode terminal 301 can be made into a structure that does not interfere with each other in the first direction (X direction). Therefore, compared with the case where the first bent portion 222B and the negative electrode terminal 301 arranged in the first through hole 123 are arranged in an overlapping manner in the first direction (X direction), the occupied width of the negative electrode sheet group 220B 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 200B in the housing 100 can be increased, so the energy density of the secondary battery 1B can be improved. In addition, on the positive electrode side, the same effect is achieved by having the same structure as that on the negative electrode side. Although the embodiments of the present invention have been described, the embodiments disclosed this time should be considered to be illustrative in all aspects and not restrictive. The scope of the present invention is indicated by the claims, and it is intended to include all changes within the meaning and scope equivalent to the claims.

Claims

1. A secondary battery, characterized in that: have: an electrode body including a first electrode and a second electrode having a polarity different from that of the first electrode; a shell that accommodates the electrode body; and a first electrode terminal, which is electrically connected to the first electrode and is disposed on the housing, The electrode body comprises: a first electrode sheet group electrically connected to the first electrode and located at an end portion of the electrode body on a first side in a first direction; and a second electrode sheet group, the second electrode sheet group being electrically connected to the second electrode and being located at an end portion of a second side opposite to the first side in the first direction, The housing comprises: a housing body having a first opening located at an end portion on the first side in the first direction; and a first sealing plate for sealing the first opening, The first sealing plate has a first end and a second end located on opposite sides to each other in a second direction orthogonal to the first direction. The first electrode sheet group includes a first bent portion that is bundled and bent, and a first front end region that is located closer to the front end side than the first bent portion. The first electrode sheet group is bent at the first bent portion so that a portion closer to the front end side than the first bent portion faces the side where the second end portion is located. The first front end 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 bent portion is located closer to the first end portion than the center of the first sealing plate in the second direction. The center of the first through hole is located closer to the second end than the center of the first sealing plate in the second direction.

2. The secondary battery according to claim 1, characterized in that: The secondary battery further includes a second electrode terminal electrically connected to the second electrode and provided on the housing. The housing includes a second sealing plate, The housing body has a second opening located at an end portion on 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 located on opposite sides to each other in the second direction, The second electrode sheet group includes a second curved portion that is bundled and curved, and a second front end region that is located closer to the front end side than the second curved portion. The second electrode sheet group is bent at the second bent portion so that a portion closer to the front end side than the second bent portion faces the side where the second end portion is located. The second front end 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 bent portion is located closer to the third end portion than the center of the second sealing plate in the second direction. The center of the second through hole is located closer to the fourth end portion than the center of the second sealing plate in the second direction.

3. The secondary battery according to claim 2, characterized in that: In the second direction, the first end portion and the third end portion are located on the same end portion side.

4. The secondary battery according to any one of claims 1 to 3, characterized in that The secondary battery further comprises a first current collecting member electrically connecting the first electrode terminal and the first electrode sheet group. The first current collecting member includes a first member and a second member, The second member is connected to the first electrode terminal, The first member has a first region connected to the second member and a second region connected to the first electrode sheet group. A step portion is provided between the first region and the second region so that positions of the first region and the second region in the first direction are different from each other. The step portion extends along a third direction that is orthogonal to the first direction and the second direction.

5. The secondary battery according to claim 4, characterized in that: The second region of the first member is arranged along the first sealing plate.

6. The secondary battery according to claim 1 or 2, characterized in that: The secondary battery further comprises a resin member disposed between the first electrode terminal and the first sealing plate. The first sealing plate further includes a covering portion that covers the first side end portion of the housing body from the first direction. The covering portion and the shell body are joined by welding.

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