Secondary battery and method for manufacturing the same

Abstract

To provide a secondary battery with high energy density and high reliability, and a method for manufacturing the secondary battery stably and efficiently.SOLUTION: A method for manufacturing a secondary battery sequentially includes the steps of: preparing an electrode body, the electrode body including a first electrode, a second electrode with a different polarity from that of the first electrode, a first electrode tab group connected to the first electrode in a first end part, and a second electrode tab group connected to the second electrode in a second end part, the first end part and the second end part being located on opposite sides; electrically connecting a first electrode terminal provided in a first sealing plate and the first electrode tab group to each other; joining the second electrode tab group to a first conductive member; inserting the electrode body into a case body from the second end part side through a first opening after joining the second electrode tab group to the first conductive member; electrically connecting the second electrode terminal provided in the second sealing plate and the second electrode tab group to each other; and sealing the opening by the sealing plate after electrically connecting the electrode terminals and the electrode tab groups together.SELECTED DRAWING: Figure 21

Description

[Technical field]

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

[0002] Japanese Patent No. 4537353 (Patent Document 1) shows a rectangular secondary battery in which an electrode group (25) is housed in a case (14) having openings (14a, 14b) at both ends, and electrode terminals (21, 23) are attached to cap plates (33, 33') that seal the openings (14a, 14b). [Prior art documents] [Patent documents]

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

[0004] For example, in manufacturing the secondary battery described in Patent Document 1, when an electrode group (25) is stored in a case (14) having openings (14a, 14b) at both ends, the electrode tab group at the leading end in the insertion direction may obstruct insertion. Also, unintended deformation may occur in the electrode tab group. From the viewpoint of stably and efficiently manufacturing a highly reliable secondary battery, there is room for further improvement in the battery described in Patent Document 1.

[0005] From a different perspective than the above, there is a demand for further improvement in the energy density of secondary batteries. From the perspective of improving energy density as well, there is still room for further improvement in the battery described in Patent Document 1.

[0006] An object of the present technology is to provide a secondary battery that is capable of stably and efficiently producing a highly reliable secondary battery having a high energy density, and a method for producing the same. [Means for solving the problem]

[0007] The present technology provides the following secondary battery and method for manufacturing the same.

[0008] [1] A process for preparing a case body having a first opening and a second opening opposite the first opening; a process for producing an electrode body including a first electrode and a second electrode having a polarity different from that of the first electrode, the electrode body having a first electrode tab group electrically connected to the first electrode at a first end portion and a second electrode tab group electrically connected to the second electrode at a second end portion opposite to the first end portion; a process for electrically connecting a first electrode terminal provided on a first sealing plate to the first electrode tab group; and a process for connecting the second electrode tab group to a first conductive member. a step of joining the second electrode tab group to a first conductive member and then inserting the electrode body into the case body from the second end side through the first opening; a step of electrically connecting a second electrode terminal provided on the second sealing plate to the second electrode tab group; a step of electrically connecting the first electrode terminal to the first electrode tab group and then sealing the first opening with the first sealing plate; and a step of electrically connecting the second electrode terminal to the second electrode tab group and then sealing the second opening with the second sealing plate.

[0009] [2] The method for manufacturing a secondary battery described in [1], wherein the step of electrically connecting the second electrode terminal and the second electrode tab group includes electrically connecting the first conductive member and the second electrode terminal after inserting the electrode body into the case body.

[0010] [3] The method for manufacturing a secondary battery described in [2], wherein electrically connecting the first conductive member and the second electrode terminal includes joining the first conductive member to a second conductive member attached to a second sealing plate.

[0011] [4] A method for manufacturing a secondary battery described in any one of [1] to [3], wherein the step of electrically connecting the first electrode terminal and the first electrode tab group includes joining the first electrode tab group to a third conductive member before inserting the electrode body into the case body.

[0012] [5] The method for manufacturing a secondary battery described in [4], wherein the step of electrically connecting the first electrode terminal and the first electrode tab group includes electrically connecting the third conductive member and the first electrode terminal before inserting the electrode body into the case body.

[0013] [6] The method for manufacturing a secondary battery described in [5], wherein electrically connecting the third conductive member and the first electrode terminal includes joining the third conductive member to a fourth conductive member attached to the first sealing plate.

[0014] [7] A method for manufacturing a secondary battery described in any one of [4] to [6], wherein the first electrode tab group has a curved portion, a tip side of the curved portion in the first electrode tab group is joined to a third conductive member, and an area of ​​the third conductive member joined to the first electrode tab group is arranged along the first sealing plate.

[0015] [8] A method for manufacturing a secondary battery described in any one of [1] to [6], wherein the second electrode tab group has a curved portion, a tip side of the curved portion of the second electrode tab group is joined to the first conductive member, and a region of the first conductive member joined to the second electrode tab group is arranged along the second sealing plate.

[0016] [9] The method for producing a secondary battery according to any one of [1] to [6], further comprising a step of covering the electrode assembly with an insulating electrode assembly holder before the electrode assembly is inserted into the case body.

[0017]

[10] An electrode assembly including a first electrode and a second electrode having a polarity different from that of the first electrode, having a first electrode tab group electrically connected to the first electrode at a first end, and having a second electrode tab group electrically connected to the second electrode at a second end opposite to the first end, a case for housing the electrode assembly, a first electrode terminal and a second electrode terminal provided in the case, a first current collector housed in the case and electrically connecting the first electrode and the first electrode terminal, and a second current collector housed in the case and electrically connecting the second electrode and the second electrode terminal, the case having a first opening and a second opening facing the first opening. a first sealing plate having a first electrode terminal and sealing the first opening, and a second sealing plate having a second electrode terminal and sealing the second opening, wherein the first electrode tab group has a first curved portion, and a tip side of the first electrode tab group relative to the first curved portion is joined to a first current collector, the second electrode tab group has a second curved portion, and a tip side of the second electrode tab group relative to the second curved portion is joined to a second current collector, a region of the first current collector joined to the first electrode tab group is disposed along the first sealing plate, and a region of the second current collector joined to the second electrode tab group is disposed along the second sealing plate.

[0018]

[11] The secondary battery described in

[10] , wherein the first sealing plate has a generally rectangular shape consisting of a pair of long sides and a pair of short sides shorter than the pair of long sides, the first current collector includes a first component joined to the first electrode tab group and a second component electrically connecting the first component and the first electrode terminal, the first component includes a first region, a second region, and a step portion formed along the pair of long sides between the first region and the second region, the first electrode tab group is joined to the first region, and the second region is disposed so as to overlap the second component.

[0019]

[12] The secondary battery described in

[10] , wherein the second sealing plate has a generally rectangular shape consisting of a pair of long sides and a pair of short sides shorter than the pair of long sides, the second current collector includes a first component joined to the second electrode tab group and a second component electrically connecting the first component and the second electrode terminal, the first component includes a first region, a second region, and a step portion formed along the pair of long sides between the first region and the second region, the second electrode tab group is joined to the first region, and the second region is disposed so as to overlap the second component. Effect of the Invention

[0020] According to the manufacturing method of the secondary battery of the present technology, in the step of inserting the electrode body into the case body, the second electrode tab group is joined to the first conductive member in advance, thereby making it possible to suppress unintended deformation (unintended bending, etc.) of the electrode tab group. As a result, it becomes possible to stably and efficiently manufacture the secondary battery.

[0021] In addition, according to the secondary battery of the present technology, the region of the current collector joined to the electrode tab group is disposed along the sealing plate, thereby improving the energy density. Also, by adopting this structure, the manufacturing method of the secondary battery described above can be easily carried out.

[0022] In this way, according to the present technology, it is possible to provide a secondary battery and a manufacturing method thereof that can stably and efficiently manufacture a secondary battery having high energy density and high reliability. [Brief description of the drawings]

[0023] [Figure 1] FIG. [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 diagram showing a connection structure between a negative electrode tab group and a negative electrode current collector. [Figure 14] FIG. 14 is a front view of the connection structure shown in FIG. [Figure 15] FIG. 14 is a cross-sectional view of the connection structure shown in FIG. [Figure 16] 11A to 11C are diagrams showing a process of inserting the electrode body into the case body. [Figure 17] 11A and 11B are diagrams showing a step of arranging a spacer between the sealing plate and the electrode body. [Figure 18] 11 is a cross-sectional view showing a state in which a spacer is disposed between a sealing plate and an electrode body. FIG. [Figure 19] FIG. 4 is a diagram showing a connection structure between a positive electrode tab group and a positive electrode current collector. [Figure 20] 20 is a cross-sectional view of the connection structure shown in FIG. 19. [Figure 21] FIG. 2 is a flow chart showing each step of a method for producing a secondary battery. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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).

[0028] In this specification, the term "battery" is not limited to lithium ion batteries, but may include other batteries such as nickel-metal hydride batteries and sodium ion batteries. In this specification, the term "electrode" may collectively refer to positive and negative electrodes. In addition, the term "electrode plate" may collectively refer to positive and negative plates.

[0029] (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.

[0030] 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.

[0031] 1 to 5, the secondary battery 1 includes an exterior body 100, an electrode assembly 200, and a current collector 300. The exterior body 100 includes a case body 110, a sealing plate 121 (first sealing plate), and a sealing plate 122 (second sealing plate).

[0032] In this specification, the X-axis direction (first direction) shown in Figures 1 to 5 may be referred to as the "width direction" of the secondary battery 1 or the case body 110, the Y-axis direction (second direction) may be referred to as the "thickness direction" of the secondary battery 1 or the case body 110, and the Z-axis direction (third direction) may be referred to as the "height direction" of the secondary battery 1 or the case body 110.

[0033] 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-axis 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.

[0034] 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.

[0035] As shown in Figures 1 and 2, sealing plates 121, 122 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 ends of bent plate-like members (joint 110A shown in Figure 2) and joining them together (for example, by laser welding). The corners of the "square tube" may have a rounded shape.

[0036] In this embodiment, the case body 110 is formed to be longer in the width direction (X-axis direction) of the secondary battery 1 than in the thickness direction (Y-axis direction) and height direction (Z-axis direction) of the secondary battery 1. The dimension (width) of the case body 110 in the X-axis 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-axis 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.

[0037] 3, an opening 111 (first opening) is provided at one end of the case body 110. The opening 111 is sealed by a sealing plate 121. A negative electrode terminal 131 (first electrode terminal), a liquid injection hole 141, and a gas exhaust valve 151 are provided on the sealing plate 121. The positions of the negative electrode terminal 131, the liquid injection hole 141, and the gas exhaust valve 151 can be changed as appropriate. The opening 111 and the sealing plate 121 have a substantially rectangular shape with the Y-axis direction as the short side direction and the Z-axis direction as the long side direction.

[0038] 4, an opening 112 (second opening) is provided at one end of the case body 110. The opening 112 is sealed by a sealing plate 122. A positive electrode terminal 132 (second electrode terminal), a liquid injection hole 142, and a gas exhaust valve 152 are provided on the sealing plate 122. The positions of the positive electrode terminal 132, the liquid injection hole 142, and the gas exhaust valve 152 can be changed as appropriate. The opening 112 and the sealing plate 122 have a substantially rectangular shape with the Y-axis direction as the short side direction and the Z-axis direction as the long side direction.

[0039] The sealing plates 121 and 122 are made of metal. Specifically, the sealing plates 121 and 122 are made of aluminum, an aluminum alloy, iron, an iron alloy, or the like.

[0040] The negative electrode terminal 131 is electrically connected to the negative electrode of the electrode assembly 200. The positive electrode terminal 132 is electrically connected to the positive electrode of the electrode assembly 200.

[0041] The negative electrode terminal 131 is made of a conductive material (more specifically, a metal), and may be made of, for example, copper or a copper alloy. The outer surface of the negative electrode terminal 131 may be provided with a portion or layer made of aluminum or an aluminum alloy.

[0042] The positive electrode terminal 132 is made of a conductive material (more specifically, a metal), and may be made of, for example, aluminum or an aluminum alloy.

[0043] The liquid inlet holes 141 and 142 are sealed with a sealing member (not shown) which may be, for example, a blind rivet or other metal member.

[0044] Gas exhaust valves 151 and 152 break when the pressure inside exterior body 100 reaches or exceeds a predetermined value, and exhaust gas inside exterior body 100 to the outside.

[0045] 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.

[0046] 5, the exterior body 100 houses the electrode body 200. The electrode body 200 is housed in the exterior body 100 so that the winding axis of the electrode body 200 is parallel to the X-axis direction.

[0047] Specifically, one or more wound electrode bodies are housed together with an electrolytic solution (electrolyte) (not shown) inside an insulating sheet 600 (described later) arranged in the exterior housing 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.

[0048] The electrode body 200 includes a negative electrode tab group 210A (first electrode tab group) provided at an end (first end) on the sealing plate 121 side, and a positive electrode tab group 220A (second electrode tab group) provided at an end (second end) on the sealing plate 122 side. The negative electrode tab group 210A and the positive electrode tab group 220A are connected to the negative electrode and positive electrode of the electrode body 200, respectively. The negative electrode tab group 210A and the positive electrode tab group 220A are formed so as to protrude from a main body portion of the electrode body 200 (a portion where a positive electrode plate and a negative electrode plate are stacked with a separator interposed therebetween) toward the sealing plates 121, 122, respectively.

[0049] The current collector 300 includes a negative electrode current collector 310 (first current collector) and a positive electrode current collector 320 (second current collector). The negative electrode current collector 310 and the positive electrode current collector 320 are each made of a plate-shaped member. The electrode body 200 is electrically connected to the negative electrode terminal 131 and the positive electrode terminal 132 via the current collector 300.

[0050] The negative electrode current collector 310 is disposed on the sealing plate 121 via a resin insulating member 410. The negative electrode current collector 310 is electrically connected to the negative electrode tab group 210A and the negative electrode terminal 131. The negative electrode current collector 310 is made of a conductive material (more specifically, a metal), and may be made of, for example, copper or a copper alloy.

[0051] The positive electrode current collector 320 is disposed on the sealing plate 122 via a resin insulating member 420. The positive electrode current collector 320 is electrically connected to the positive electrode tab group 220A and the positive electrode terminal 132. The positive electrode current collector 320 is made of a conductive material (more specifically, a metal), and may be made of, for example, aluminum or an aluminum alloy. The positive electrode tab group 220A may be electrically connected to the sealing plate 122 directly or via the positive electrode current collector 320. In this case, the sealing plate 122 may also serve as the positive electrode terminal 132.

[0052] (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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] As shown in Fig. 8, a plurality of negative electrode tabs 210B each 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 210B are stacked to form a negative electrode tab group 210A. The position and length in the protruding direction of each of the plurality of negative electrode tabs 210B are appropriately adjusted taking into consideration the state in which the negative electrode tab group 210A is connected to the negative electrode current collector 310. The shape of the negative electrode tab 210B is not limited to that exemplified in Fig. 8.

[0058] FIG. 9 is a front view showing the positive electrode original plate 220S before the positive electrode plate 220 (second electrode) is formed, FIG. 10 is a cross-sectional view taken along line XX of the positive electrode original plate 220S shown in FIG. 9, and FIG. 11 is a front view showing the positive electrode plate 220 formed from the positive electrode original plate 220S.

[0059] The positive electrode plate 220 is manufactured by processing a positive electrode original plate 220S. As shown in Figures 9 and 10, the positive electrode original plate 220S includes a positive electrode core 221, a positive electrode active material layer 222, and a positive electrode protective layer 223. The positive electrode core 221 is an aluminum foil or an aluminum alloy foil.

[0060] A positive electrode active material layer 222 is formed on both sides of the positive electrode core 221 except for one end portion. The positive electrode active material layer 222 is formed on the positive electrode core 221 by applying a positive electrode active material layer slurry with a die coater.

[0061] 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.

[0062] The positive electrode protective layer 223 is in contact with the positive electrode core 221 and is formed at one end in the width direction of the positive electrode active material layer 222. The positive electrode protective layer 223 is formed on the positive electrode core 221 by applying a positive electrode protective layer slurry with a die coater. The positive electrode protective layer 223 has a larger electric resistance than the positive electrode active material layer 222.

[0063] 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.

[0064] The positive electrode core 221 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 222 and the positive electrode protective layer 223. Furthermore, the positive electrode active material layer 222 is compressed to form a positive electrode original plate 220S including the positive electrode core 221, the positive electrode active material layer 222, and the positive electrode protective layer 223. The positive electrode original plate 220S is cut into a predetermined shape to form the positive electrode plate 220. The positive electrode original plate 220S can be cut by laser processing using energy beam irradiation, die processing, cutter processing, or the like.

[0065] As shown in Fig. 11, a plurality of positive electrode tabs 220B made of a positive electrode core 221 are provided at one end in the width direction of a positive electrode plate 220 formed from a positive electrode original plate 220S. When the positive electrode plate 220 is wound, the plurality of positive electrode tabs 220B are stacked to form a positive electrode tab group 220A. The position and length in the protruding direction of each of the plurality of positive electrode tabs 220B are appropriately adjusted in consideration of the state in which the positive electrode tab group 220A is connected to the positive electrode current collector 320. The shape of the positive electrode tabs 220B is not limited to that exemplified in Fig. 11.

[0066] A positive electrode protection layer 223 is provided at the base of each of the positive electrode tabs 220B. The positive electrode protection layer 223 does not necessarily have to be provided at the base of the positive electrode tab 220B.

[0067] In a typical example, the thickness of the negative electrode tab 210B (one piece) is smaller than the thickness of the positive electrode tab 220B (one piece). In this case, the thickness of the negative electrode tab group 210A is smaller than the thickness of the positive electrode tab group 220A.

[0068] (Connection structure between electrode body 200 and current collector 300) Fig. 12 is a diagram showing the electrode body 200 and the current collector 300 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.

[0069] The negative electrode tab group 210A is joined to the negative electrode current collector 310 at a joint 310A, and the positive electrode tab group 220A is joined to the positive electrode current collector 320 at a joint 320A. The joints 310A, 320A can be formed by, for example, ultrasonic bonding, resistance welding, laser welding, crimping, etc. The joints 310A, 320A form conductive paths between the negative electrode tab group 210A and the positive electrode tab group 220A and the negative electrode terminal 131 and the positive electrode terminal 132.

[0070] (Connection structure between electrode body 200 and negative electrode current collector 310) Fig. 13 is a diagram showing a connection structure between negative electrode tab group 210A and negative electrode current collector 310. Fig. 14 and Fig. 15 are a front view and a cross-sectional view, respectively, of the connection structure shown in Fig. 13.

[0071] 13 to 15, the negative electrode current collector 310 is connected to the negative electrode terminal 131 between the electrode body 200 and the sealing plate 121. The negative electrode current collector 310 includes a first conductive member 311 and a second conductive member 312. The first conductive member 311 and the second conductive member 312 are joined at a joint 313.

[0072] The negative electrode tab group 210A is joined to a first conductive member 311 of the negative electrode current collector 310 at a joint 310A. The first conductive member 311 is connected to a second conductive member 312 at a joint 313. The joint 313 can be formed by, for example, ultrasonic bonding, resistance welding, laser welding, crimping, or the like.

[0073] The first conductive member 311 and the second conductive member 312 are attached to the inner surface side of the sealing plate 121 via an insulating member 410 made of resin.

[0074] The negative electrode terminal 131 is attached to the sealing plate 121 via a resin insulating member 410A. The negative electrode terminal 131 is provided so as to be exposed to the outside of the sealing plate 121 and reach the second conductive member 312 of the negative electrode current collector 310 provided on the inner side of the sealing plate 121. The negative electrode terminal 131 and the second conductive member 312 can be connected to each other by, for example, ultrasonic bonding, resistance welding, laser welding, crimping, or the like. In this embodiment, a through hole is provided in the second conductive member 312, the negative electrode terminal 131 is inserted into the through hole, the negative electrode terminal 131 is crimped on the second conductive member 312, and then the crimped portion and the second conductive member 312 are welded at a joint portion 131A to connect the negative electrode terminal 131 and the second conductive member 312.

[0075] As a procedure for assembling each part, first, the negative electrode terminal 131 and the second conductive member 312 are attached to the sealing plate 121 together with the insulating members 410 and 410A. Next, the first conductive member 311 connected to the electrode body 200 is attached to the second conductive member 312. At this time, the first conductive member 311 is placed on the insulating member 410 so that a portion of the first conductive member 311 overlaps with the second conductive member 312. Next, the first conductive member 311 and the second conductive member 312 are welded and connected at the joint 313. Note that the insulating members 410 and 410A may be composed of a single member.

[0076] However, the negative electrode terminal 131 may be electrically connected to the sealing plate 121. Also, the sealing plate 121 may serve as the negative electrode terminal 131.

[0077] 13 to 15, the negative electrode current collector 310 is illustrated as being made up of two components (the first conductive member 311 and the second conductive member 312), but the negative electrode current collector 310 may be made up of a single component.

[0078] (Step of Inserting the Electrode Body 200) 16 is a diagram showing a process of inserting the electrode body 200 into the case body 110. As shown in FIG. 16, a resin insulating sheet 600 (electrode body holder) is disposed between the electrode body 200 and the case body 110.

[0079] The insulating sheet 600 may be made of, for example, resin. More specifically, the material of the insulating sheet 600 may be, for example, polypropylene (PP), polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polyimide (PI), or polyolefin (PO).

[0080] The insulating sheet 600 does not necessarily have to cover the entire surface of the electrode body 200. The insulating sheet 600 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 600 preferably covers the entire four faces other than at least the two faces on which the negative electrode tab group 210A and the positive electrode tab group 220A are formed, respectively.

[0081] Fig. 17 is a diagram showing a process of arranging a spacer 510 between the sealing plate 121 and the electrode body 200. Fig. 18 is a cross-sectional view showing a state in which the spacer 510 is arranged between the sealing plate 121 and the electrode body 200.

[0082] 17 and 18, the negative electrode tab group 210A extending from the electrode body 200 toward the sealing plate 121 is curved from the center in the Y-axis direction of the sealing plate 121 toward the end, and then bent back toward the center. A spacer 510 is arranged to accommodate the curved negative electrode tab group 210A (curved portion).

[0083] The spacer 510 includes a first spacer 511 and a second spacer 512. The first spacer 511 and the second spacer 512 are engaged with each other by sliding them along the Y-axis direction from the end side toward the center side of the sealing plate 121. As a result, the spacer 510 is fixed to the sealing plate 121 via the insulating member 410, and the positional stability of the spacer 510 is increased.

[0084] 18, the spacer 510 forms an internal space for accommodating the negative electrode current collector 310, and the tip portion of the negative electrode tab group 210A is also accommodated in the internal space of the spacer 510. The spacer 510 has a hole that allows the negative electrode tab group 210A to pass therethrough.

[0085] The material of the spacer 510 is not particularly limited, but it is preferable to use an insulating material such as resin. More specifically, it is preferable to use a sheet made of polyolefin (PO). In addition, an insulating sheet 600 may be interposed between the spacer 510 and the electrode body 200.

[0086] Referring again to FIG. 16, in the manufacturing method of the secondary battery 1 according to this embodiment, the positive electrode tab group 220A is joined to the first conductive member 321 of the positive electrode current collector 320, and then the electrode body 200 is inserted into the case body 110 from the end side on the positive electrode tab group 220A side.

[0087] When the electrode body 200 is inserted into the case body 110 through the opening 111, unintended deformation may occur in the positive electrode tab group 220A located at the front side. In response to this, by joining the positive electrode tab group 220A to the first conductive member 321 of the positive electrode current collector 320 and then inserting the electrode body 200 into the case body 110, unintended deformation of the positive electrode tab group 220A can be suppressed. As a result, it is possible to stably and efficiently manufacture a highly reliable secondary battery 1.

[0088] 16, the electrode body 200 is inserted into the case body 110 in a state where the electrode body 200 is covered with the insulating sheet 600. This makes it possible to suppress damage to the electrode body 200 when it is inserted into the case body 110.

[0089] 16, after the negative electrode terminal 131 and the negative electrode tab group 210A are electrically connected, the electrode assembly 200 is inserted into the case body 110 through the opening 111 from the end side on the positive electrode tab group 220A side. When the negative electrode terminal 131 attached to the sealing plate 121 and the negative electrode tab group 210A are electrically connected after the electrode assembly 200 is inserted into the case body 110, the negative electrode tab group 210A is required to have a length such that the negative electrode tab group 210A of the electrode assembly 200 stored in the case body 110 sufficiently protrudes outside the case body 110. By electrically connecting the negative electrode terminal 131 attached to the sealing plate 121 and the negative electrode tab group 210A before inserting the electrode assembly 200 into the case body 110, the length of the negative electrode tab group 210A can be reduced compared to the case where the connection is made after the electrode assembly 200 is inserted into the case body 110. As a result, the volume occupancy rate of the negative electrode plate 210 and the positive electrode plate 220 in the internal space of the case body 110 can be increased.

[0090] During the step of inserting the electrode body 200, the case body 110 can be held at a predetermined angle. As an example, it is preferable to insert the electrode body 200 in a state where the case body 110 is held so that the X-axis direction (width direction of the case body 110) intersects with the horizontal direction at an angle of about ±45° or less. For example, the electrode body 200 can be inserted into the case body 110 with the case body 110 tilted so that the upper end of the opening 111 into which the electrode body 200 is inserted is positioned higher than the upper end of the opening 112 in the vertical direction.

[0091] The step of inserting the electrode body 200 is not limited to a mode in which the electrode body 200 is pushed in from the opening 111 side, but may be a mode in which the electrode body 200 is pulled from the opening 112 side, for example.

[0092] (Connection structure between electrode body 200 and positive electrode current collector 320) Fig. 19 is a diagram showing a connection structure between positive electrode tab group 220A and positive electrode current collector 320. Fig. 20 is a cross-sectional view of the connection structure shown in Fig. 19.

[0093] 19 and 20, the positive electrode current collector 320 is provided on the inner surface side of the sealing plate 122, and is connected to the electrode body 200 and the positive electrode terminal 132. The positive electrode current collector 320 includes a first conductive member 321 (first part) and a second conductive member 322 (second part). The first conductive member 321 and the second conductive member 322 are joined at a joint 323. The first conductive member 321 and the second conductive member 322 are attached to the inner surface side of the sealing plate 122 via an insulating member 420 made of resin.

[0094] The first conductive member 321 has a step portion 321A. The step portion 321A extends in the long side direction (Z-axis direction) of the rectangular sealing plate 122. As shown in FIG. 20, in a region (first region) on one side (left side in FIG. 20) of the step portion 321A, the first conductive member 321 is provided along the sealing plate 122 and is joined to the positive electrode tab group 220A (joint portion 320A). In a region (second region) on the other side (right side in FIG. 20) of the step portion 321A, the first conductive member 321 is provided to overlap with the second conductive member 322. These configurations are similar on the negative electrode side (see FIGS. 13 to 15).

[0095] 19 and 20 show the shape of the positive electrode tab group 220A before it is curved, but in the completed secondary battery 1, the positive electrode tab group 220A is stored in a curved state in the case body 110. Before storing the electrode body 200 in the case body 110, it is preferable to curve (shape) the positive electrode tab group 220A until it is close to its final shape.

[0096] The positive electrode tab group 220A is joined to a first conductive member 321 of the positive electrode current collector 320 at a joint 320A. The first conductive member 321 is connected to a second conductive member 322 at a joint 323. The joint 323 can be formed by, for example, ultrasonic bonding, resistance welding, laser welding, crimping, or the like.

[0097] The positive electrode terminal 132 is attached to the sealing plate 122 via a resin insulating member 420A. The positive electrode terminal 132 is provided so as to be exposed to the outside of the sealing plate 122 and reach the second conductive member 322 of the positive electrode current collector 320 provided on the inner side of the sealing plate 122. The positive electrode terminal 132 and the second conductive member 322 can be connected by, for example, ultrasonic bonding, resistance welding, laser welding, crimping, or the like. In this embodiment, a through hole is provided in the second conductive member 322, the positive electrode terminal 132 is inserted into the through hole, the positive electrode terminal 132 is crimped on the second conductive member 322, and then the crimped portion and the second conductive member 322 are welded at a joint 132A to connect the positive electrode terminal 132 and the second conductive member 322.

[0098] As a procedure for assembling each part, first, the positive electrode terminal 132 and the second conductive member 322 are attached to the sealing plate 122 together with the insulating members 420 and 420A. Next, the first conductive member 321 connected to the electrode body 200 is attached to the second conductive member 322. At this time, the first conductive member 321 is placed on the insulating member 420 so that a portion of the first conductive member 321 overlaps with the second conductive member 322. Next, the first conductive member 321 and the second conductive member 322 are welded and connected at the joint 323. Note that the insulating members 420 and 420A may be composed of a single member.

[0099] However, the positive electrode terminal 132 may be electrically connected to the sealing plate 122. Also, the sealing plate 122 may serve as the positive electrode terminal 132.

[0100] 19 and 20 show an example of the positive electrode current collector 320 made up of two parts (first conductive member 321 and second conductive member 322), but the positive electrode current collector 320 may be made up of a single part.

[0101] (Manufacturing process of secondary battery 1) Fig. 21 is a flow diagram showing each step of the manufacturing method of the secondary battery 1. As shown in Fig. 21, in S10, the case body 110 is prepared. Next, in S20, the electrode body 200 is produced. In S30, the electrode terminals provided on the sealing plates 121, 122 and the electrode tab group of the electrode body 200 are electrically connected. In the example of Fig. 21, first, the negative electrode terminal 131 and the negative electrode tab group 210A are electrically connected (S31), and then the positive electrode terminal 132 and the positive electrode tab group 220A are electrically connected (S32).

[0102] To electrically connect the positive electrode terminal 132 and the positive electrode tab group 220A, first, the first conductive member 321 of the positive electrode current collector 320 and the positive electrode tab group 220A are joined (S32A), and then the electrode body 200 is inserted into the case body 110 (S40). After the electrode body 200 is inserted into the case body 110, the first conductive member 311 and the second conductive member 312 are joined, thereby electrically connecting the positive electrode terminal 132 and the positive electrode tab group 220A (S32B).

[0103] After completing the connection between the electrode terminals and the electrode tab group (S30) and the insertion of the electrode body 200 (S40), the openings 111, 112 are sealed with sealing plates 121, 122, respectively (S50). The sealing step with sealing plates 121, 122 is performed by, for example, laser welding.

[0104] In the present technology, the order of connecting the negative electrode terminal 131 and the negative electrode tab group 210A (S31), connecting the positive electrode terminal 132 and the positive electrode tab group 220A (S32), and inserting the electrode body 200 (S40) is not limited to the example in Fig. 21 and can be changed as appropriate. For example, there is a case where the connection (S32) between the positive electrode terminal 132 and the positive electrode tab group 220A is performed, and then the connection (S31) between the negative electrode terminal 131 and the negative electrode tab group 210A is performed.

[0105] 21, the step (S51) of sealing opening 111 with sealing plate 121 on the negative electrode side is performed followed by the step (S52) of sealing opening 112 with sealing plate 122 on the positive electrode side, but the step (S51) of sealing opening 111 with sealing plate 121 may be performed after the step (S52) of sealing opening 112 with sealing plate 122. Furthermore, at least some of the steps (S51, S52) of sealing with sealing plates 121, 122 can be performed simultaneously.

[0106] (summary) The above-mentioned contents regarding the secondary battery 1 according to the present embodiment and the manufacturing method thereof can be summarized as follows.

[0107] As shown in FIG. 21 , the method of manufacturing the secondary battery 1 includes a step (S10) of preparing a case body 110 having an opening 111 and an opening 112 facing the opening 111, and a step of preparing a negative electrode plate 210 and a positive electrode plate 220. The step of preparing a positive electrode tab group 220A includes a negative electrode tab 210B at one end and a positive electrode tab 220B at the other end. The method includes a step (S20) of preparing an electrode assembly 200 having a positive electrode tab group (A), a step (S30) of electrically connecting electrode terminals provided on sealing plates 121, 122 to an electrode tab group of the electrode assembly 200, a step (S40) of inserting the electrode assembly 200 into the case body 110 from the end side on the positive electrode tab group 220A side through the opening 111, and a step (S50) of sealing the openings 111, 112 with sealing plates 121, 122. Here, the positive electrode tab group 220A is joined to the first conductive member 321 of the positive electrode current collector 320 (S32A), and then the electrode assembly 200 is inserted into the case body 110 from the end side on the positive electrode tab group 220A side through the opening 111 (S40), and the positive electrode terminal 132 provided on the sealing plate 122 is electrically connected to the positive electrode tab group 220A (S32B).

[0108] In the method for manufacturing the secondary battery 1 according to the example, the electrical connection between the positive electrode terminal 132 and the positive electrode tab group 220A is achieved by joining the first conductive member 321 to the second conductive member 322 provided on the sealing plate 122.

[0109] In one example of a method for manufacturing a secondary battery 1, the negative electrode terminal 131 and the negative electrode tab group 210A are electrically connected by joining the negative electrode tab group 210A to a first conductive member 311 (third conductive member) of the negative electrode current collector 310, and then joining the first conductive member 311 (third conductive member) to a second conductive member 312 (fourth conductive member) provided on the sealing plate 121.

[0110] In a manufacturing method of a secondary battery 1 according to an example, the electrode body 200 may be covered with an insulating sheet 600 before being inserted into the case body 110. However, in the present technology, the insulating sheet 600 covering the electrode body 200 is not necessarily required.

[0111] The secondary battery 1 according to this embodiment includes an electrode body 200 in which a negative electrode tab group 210A is provided on the sealing plate 121 side and a positive electrode tab group 220A is provided on the sealing plate 122 side, an exterior body 100 (case) that houses the electrode body 200, a negative electrode terminal 131 (first electrode terminal) and a positive electrode terminal 132 (second electrode terminal) provided on the exterior body 100, a negative electrode current collector 310 (first current collector) that is housed in the exterior body 100 and electrically connects the negative electrode tab group 210A and the negative electrode terminal 131, and a positive electrode current collector 320 (second current collector) that is housed in the exterior body 100 and electrically connects the positive electrode tab group 220A and the positive electrode terminal 132.

[0112] The negative electrode tab group 210A and the positive electrode tab group 220A each have a curved portion. The negative electrode tab group 210A and the positive electrode tab group 220A are joined to the negative electrode current collector 310 and the positive electrode current collector 320, respectively, at joints 310A and 320A located on the tip side of the curved portion. In the region where the joints 310A and 320A are located, the first conductive members 311 and 321 of the negative electrode current collector 310 and the positive electrode current collector 320 are arranged along the sealing plates 121 and 122.

[0113] (Action and effect) According to the secondary battery 1 of this embodiment, the electrode body 200 is inserted into the case body 110 having openings 111, 112 facing each other, and a negative terminal 131 and a positive terminal 132 are respectively provided on sealing plates 121, 122 that seal the openings 111, 112, respectively, thereby reducing the height of the secondary battery 1 and improving the mountability of the secondary battery 1 in a vehicle.

[0114] Furthermore, by arranging the areas where the joints 310A, 320A between the negative electrode tab group 210A and the positive electrode tab group 220A of the negative electrode current collector 310 and the positive electrode current collector 320 are located along the sealing plates 121, 122, respectively, the energy density of the secondary battery 1 can be improved.

[0115] According to the method for manufacturing the secondary battery 1 according to this embodiment, the positive electrode tab group 220A is joined to the first conductive member 321 (S32A) before the step (S40) of inserting the electrode body 200 into the case body 110. This makes it possible to insert the electrode body 200 while suppressing unintended deformation (unintended bending, etc.) of the positive electrode tab group 220A located at the leading end in the insertion direction of the electrode body 200. This makes it possible to stably and efficiently manufacture the secondary battery 1.

[0116] According to the secondary battery 1 of this embodiment, since the positive electrode tab group 220A is joined to the first conductive member 321 included in the positive electrode current collector 320, it is easy to implement the above-mentioned manufacturing method in which the positive electrode tab group 220A is collected (S32A) before the electrode body 200 insertion step (S40).

[0117] As described above, the secondary battery 1 according to the present embodiment and the manufacturing method thereof make it possible to stably and efficiently manufacture a highly reliable secondary battery having a high energy density.

[0118] 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]

[0119] 1 secondary battery, 100 exterior body, 110 case body, 110A joint, 111, 112 opening, 121, 122 sealing plate, 131 negative electrode terminal, 131A joint, 132 positive electrode terminal, 132A joint, 141, 142 liquid injection hole, 151, 152 gas exhaust valve, 200, 201, 202 electrode body, 210 negative electrode plate, 210A negative electrode tab group, 210B negative electrode tab, 210S negative electrode base plate, 211 negative electrode core, 212 negative electrode active material layer, 220 positive electrode plate, 220A positive electrode tab group, 220B positive electrode tab, 220S positive electrode base plate, 221 positive electrode core, 222 positive electrode active material layer, 223 positive electrode protective layer, 300 Current collector, 310, negative electrode current collector, 310A, joint portion, 311, first conductive member, 312, second conductive member, 313, joint portion, 320, positive electrode current collector, 320A, joint portion, 321, first conductive member, 321A, step portion, 322, second conductive member, 323, joint portion, 410, 410A, 420, 420A, insulating member, 510, spacer, 511, first spacer, 512, second spacer, 600, insulating sheet.

Claims

1. preparing a case body having a first opening and a second opening opposite the first opening; a step of producing an electrode body including a first electrode and a second electrode having a polarity different from that of the first electrode, the electrode body having a first electrode tab group electrically connected to the first electrode at a first end, and a second electrode tab group electrically connected to the second electrode at a second end opposite to the first end; a step of electrically connecting first electrode terminals provided on a first sealing plate to the first electrode tab group; joining the second electrode tab group to a first conductive member; a step of joining the second electrode tab group to the first conductive member, and then inserting the electrode body into the case body from the second end side through the first opening; a step of electrically connecting second electrode terminals provided on a second sealing plate to the second electrode tab group; a step of sealing the first opening with the first sealing plate after electrically connecting the first electrode terminals and the first electrode tab group; and then sealing the second opening with the second sealing plate after electrically connecting the second electrode terminal and the second electrode tab group.

2. 2. The method for manufacturing a secondary battery according to claim 1, wherein the step of electrically connecting the second electrode terminal and the second electrode tab group includes electrically connecting the first conductive member and the second electrode terminal after inserting the electrode body into the case body.

3. 3. The method for manufacturing a secondary battery according to claim 2, wherein electrically connecting the first conductive member and the second electrode terminal includes joining the first conductive member to a second conductive member attached to the second sealing plate.

4. 2. The method for manufacturing a secondary battery according to claim 1, wherein the step of electrically connecting the first electrode terminal and the first electrode tab group includes joining the first electrode tab group to a third conductive member before inserting the electrode body into the case body.

5. 5. The method for manufacturing a secondary battery according to claim 4, wherein the step of electrically connecting the first electrode terminal and the first electrode tab group includes electrically connecting the third conductive member and the first electrode terminal before inserting the electrode body into the case body.

6. 6. The method for manufacturing a secondary battery according to claim 5, wherein electrically connecting the third conductive member and the first electrode terminal includes joining the third conductive member to a fourth conductive member attached to the first sealing plate.

7. the first electrode tab group has a curved portion, and a tip side of the first electrode tab group relative to the curved portion is joined to the third conductive member, 7 . The method for manufacturing a secondary battery according to claim 4 , wherein a region of the third conductive member joined to the first electrode tab group is disposed along the first sealing plate.

8. the second electrode tab group has a curved portion, and a tip side of the second electrode tab group relative to the curved portion is joined to the first conductive member, The method for manufacturing a secondary battery according to claim 1 , wherein a region of the first conductive member joined to the second electrode tab group is disposed along the second sealing plate.

9. The method for manufacturing a secondary battery according to claim 1 , further comprising the step of covering the electrode assembly with an insulating electrode assembly holder before the electrode assembly is inserted into the case body.

10. an electrode body including a first electrode and a second electrode having a polarity different from that of the first electrode, having a first electrode tab group electrically connected to the first electrode at a first end, and having a second electrode tab group electrically connected to the second electrode at a second end opposite to the first end; A case that accommodates the electrode assembly; a first electrode terminal and a second electrode terminal provided on the case; a first current collector that is accommodated in the case and electrically connects the first electrode and the first electrode terminal; a second current collector that is housed in the case and electrically connects the second electrode and the second electrode terminal; The case is a case body having a first opening and a second opening opposite the first opening; a first sealing plate provided with the first electrode terminal and sealing the first opening; a second sealing plate provided with the second electrode terminal and sealing the second opening, the first electrode tab group has a first curved portion, and a tip side of the first electrode tab group relative to the first curved portion is joined to the first current collector; the second electrode tab group has a second curved portion, and a tip side of the second electrode tab group relative to the second curved portion is joined to the second current collector, a region of the first current collector joined to the first electrode tab group is disposed along the first sealing plate, a region of the second current collector joined to the second electrode tab group is disposed along the second sealing plate.

11. The first sealing plate has a generally rectangular shape including a pair of long sides and a pair of short sides that are shorter than the pair of long sides, the first current collector includes a first component joined to the first electrode tab group and a second component electrically connecting the first component and the first electrode terminal, the first component includes a first region, a second region, and a step portion formed along the pair of long sides between the first region and the second region, The secondary battery according to claim 10 , wherein the first electrode tab group is joined to the first region, and the second region is disposed to overlap the second component.

12. the second sealing plate has a generally rectangular shape including a pair of long sides and a pair of short sides that are shorter than the pair of long sides, the second current collector includes a first component joined to the second electrode tab group and a second component electrically connecting the first component and the second electrode terminal, the first component includes a first region, a second region, and a step portion formed along the pair of long sides between the first region and the second region, The secondary battery according to claim 10 , wherein the second electrode tab group is joined to the first region, and the second region is disposed so as to overlap the second component.

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