Secondary battery and method for manufacturing same
By using the combination of bending electrode sheet sets and conductive components and a specific insertion sequence during the manufacturing process of the secondary battery, the problems of insertion obstacles and deformation of the electrode sheet sets are solved, the energy density and reliability of the secondary battery are improved, and the vehicle is enhanced Carrying.
Patent Information
- Application Number
- CN202410729122.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2023-06-08
- Filing Date
- 2024-06-06
- Publication Date
- 2024-12-10
AI Technical Summary
During the manufacturing process, the electrode sheet sets may hinder insertion, resulting in undesirable deformation, and insufficient energy density, making it difficult to manufacture a high-reliability secondary battery stably and efficiently.
Using a combination of the electrode sheet set with a bent portion and a conductive component, the electrode body is ensured to be stably inserted into the shell main body through a specific insertion and sealing sequence and insulating sheet, and the bonding efficiency of the electrode sheet set is improved, and the internal space of the battery is increased. Utilization.
A stable and efficient manufacturing of secondary batteries with high energy density and reliability is achieved, reducing the battery height and improving vehicle carryingability and energy density.
Smart Images
Figure CN119108769A_ABST
Abstract
Description
Technical Field
[0001] The present technology relates to a secondary battery and a method for manufacturing the same. Background Art
[0002] Japanese Patent Gazette No. 4537353 discloses a square secondary battery in which an electrode group (25) is housed in a housing (14) having openings (14a, 14b) at both ends, and electrode terminals (21, 23) are respectively mounted on covers (33, 33') for sealing the openings (14a, 14b).
[0003] For example, when manufacturing the secondary battery described in Japanese Patent No. 4537353, when the electrode group (25) is housed in a housing (14) having openings (14a, 14b) at both ends, the electrode sheet group on the front side of the insertion direction may hinder the insertion. In addition, the electrode sheet group may be deformed undesirably. From the perspective of stably and efficiently manufacturing highly reliable secondary batteries, the battery described in Japanese Patent No. 4537353 still has room for further improvement.
[0004] 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, the battery described in Japanese Patent No. 4537353 also has room for further improvement. Summary of the Invention
[0005] The present technology aims to provide a secondary battery and a method for manufacturing the same, which are capable of stably and efficiently manufacturing a secondary battery having high energy density and high reliability.
[0006] The present technology provides the following secondary batteries and methods of manufacturing the same.
[0007] [1] A method for manufacturing a secondary battery, comprising the following steps: preparing a shell body having a first opening and a second opening opposite to the first opening; forming an electrode body, wherein the electrode body includes a first electrode and a second electrode having a polarity different from that of the first electrode, the electrode body having a first electrode sheet group electrically connected to the first electrode at a first end thereof, and a second electrode sheet group electrically connected to the second electrode at a second end located on the opposite side to the first end; and connecting a first electrode terminal provided on a first sealing plate to the first electrode sheet group. The process of electrically connecting; the process of joining the second electrode sheet group to the first conductive component; the process of inserting the electrode body into the shell body from the side where the second end is located through the first opening after joining the second electrode sheet group to the first conductive component; the process of electrically connecting the second electrode terminal provided on the second sealing plate to the second electrode sheet group; the process of sealing the first opening with the first sealing plate after electrically connecting the first electrode terminal to the first electrode sheet group; and the process of sealing the second opening with the second sealing plate after electrically connecting the second electrode terminal to the second electrode sheet group.
[0008] [2] In the method for manufacturing a secondary battery described in [1], the step of electrically connecting the second electrode terminal to the second electrode sheet group includes electrically connecting the first conductive member to the second electrode terminal after inserting the electrode body into the case body.
[0009] [3] In the method for manufacturing a secondary battery according to [2], electrically connecting the first conductive member to the second electrode terminal includes joining the first conductive member to a second conductive member attached to the second sealing plate.
[0010] [4] In the method for manufacturing a secondary battery according to any one of [1] to [3], the step of electrically connecting the first electrode terminal to the first electrode sheet group includes joining the first electrode sheet group to the third conductive member before inserting the electrode body into the case body.
[0011] [5] In the method for manufacturing a secondary battery described in [4], the step of electrically connecting the first electrode terminal to the first electrode sheet group includes electrically connecting the third conductive member to the first electrode terminal before inserting the electrode body into the case body.
[0012] [6] In the method for manufacturing a secondary battery according to [5], electrically connecting the third conductive member to the first electrode terminal includes joining the third conductive member to a fourth conductive member attached to the first sealing plate.
[0013] [7] In the method for manufacturing a secondary battery described in any one of [4] to [6], the first electrode sheet group has a bent portion, a portion of the first electrode sheet group closer to the front end than the bent portion is joined to the third conductive component, and an area of the third conductive component joined to the first electrode sheet group is arranged along the first sealing plate.
[0014] [8] In the method for manufacturing a secondary battery described in any one of [1] to [7], the second electrode sheet group has a bent portion, a portion of the second electrode sheet group closer to the front end than the bent portion is joined to the first conductive component, and the area of the first conductive component joined to the second electrode sheet group is arranged along the second sealing plate.
[0015] [9] The method for manufacturing a secondary battery according to any one of [1] to [8] further comprises the step of covering the electrode body before insertion into the case body with an insulating electrode body holder.
[0016]
[10] A secondary battery comprising: an electrode body comprising a first electrode and a second electrode having a polarity different from that of the first electrode, the electrode body having a first electrode sheet group electrically connected to the first electrode at a first end thereof, and a second electrode sheet group electrically connected to the second electrode at a second end located on the opposite side to the first end; a shell housing the electrode body; a first electrode terminal and a second electrode terminal disposed in the shell; a first current collector housed in the shell and electrically connecting the first electrode to the first electrode terminal; and a second current collector housed in the shell and electrically connecting the second electrode to the second electrode terminal, the shell comprising: a shell body The body has a first opening and a second opening opposite to the first opening; a first sealing plate, which seals the first opening and is provided with a first electrode terminal; and a second sealing plate, which seals the second opening and is provided with a second electrode terminal, the first electrode sheet group has a first bent portion, and a portion of the first electrode sheet group closer to the front end side than the first bent portion is joined to the first current collector, the second electrode sheet group has a second bent portion, and a portion of the second electrode sheet group closer to the front end side than the second bent portion is joined to the second current collector, the region of the first current collector joined to the first electrode sheet group is arranged along the first sealing plate, and the region of the second current collector joined to the second electrode sheet group is arranged along the second sealing plate.
[0017]
[11] In the secondary battery described in
[10] , the first sealing plate has a roughly rectangular shape consisting of a pair of long sides and a pair of short sides shorter than the pair of long sides, and the first current collector includes: a first part, which is joined to the first electrode sheet group; and a second part, which electrically connects the first part to the first electrode terminal, the first part 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 sheet group is joined to the first region, and the second region is arranged so as to overlap with the second part.
[0018]
[12] In the secondary battery described in
[10] , the second sealing plate has a roughly rectangular shape consisting of a pair of long sides and a pair of short sides shorter than the pair of long sides, and the second current collector includes: a first part, which is joined to the second electrode sheet group; and a second part, which electrically connects the first part to the second electrode terminal, the first part 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 sheet group is joined to the first region, and the second region is arranged in a manner overlapping with the second part.
[0019] 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
[0020] Figure 1 It is a front view of the secondary battery.
[0021] Figure 2 It means observing from the direction of arrow II Figure 1 The diagram shows the state of the secondary battery.
[0022] Figure 3 It means observing from the direction of arrow III Figure 1 The diagram shows the state of the secondary battery.
[0023] Figure 4 It indicates viewing from the direction of arrow IV Figure 1 The diagram shows the state of the secondary battery.
[0024] Figure 5 yes Figure 1 A front cross-sectional view of a secondary battery is shown.
[0025] Figure 6 This is a front view showing a negative electrode original plate before forming the negative electrode plate.
[0026] Figure 7 yes Figure 6 VII-VII cross-sectional view of the negative electrode original plate shown.
[0027] Figure 8 It is a front view showing a negative electrode plate formed from a negative electrode original plate.
[0028] Figure 9 This is a front view showing a positive electrode original plate before forming the positive electrode plate.
[0029] Figure 10 yes Figure 9 XX cross-sectional view of the positive electrode original plate shown.
[0030] Figure 11 It is a front view showing a positive electrode plate formed from a positive electrode original plate.
[0031] Figure 12 It is a diagram showing an electrode body and a current collector removed from a secondary battery.
[0032] Figure 13 A diagram showing the connection structure between the negative electrode sheet group and the negative electrode current collector.
[0033] Figure 14 yes Figure 13 Front view of the connection structure shown.
[0034] Figure 15 yes Figure 13 A cross-sectional view of the connection structure shown.
[0035] Figure 16 This is a diagram showing the step of inserting the electrode assembly into the case body.
[0036] Figure 17 This is a diagram showing the step of placing a separator between the sealing plate and the electrode assembly.
[0037] Figure 18 It is a cross-sectional view showing a state where a separator is arranged between the sealing plate and the electrode body.
[0038] Figure 19 It is a diagram showing the connection structure between the positive electrode sheet group and the positive electrode current collector.
[0039] Figure 20 yes Figure 19 A cross-sectional view of the connection structure shown.
[0040] Figure 21 This is a flowchart showing each step of a method for manufacturing a secondary battery. DETAILED DESCRIPTION
[0041] Hereinafter, embodiments of the present technology will be described. The same or corresponding parts will be denoted by the same reference numerals and their description may not be repeated.
[0042] In addition, in the embodiments described below, when numbers, amounts, etc. are mentioned, unless otherwise specified, the scope of the present technology is not necessarily limited to those numbers, amounts, etc. In addition, in the embodiments described below, unless otherwise specified, individual components are not necessarily essential to the present technology. Furthermore, the present technology is not necessarily limited to technologies that achieve all the effects described in the embodiments.
[0043] In this specification, the terms "comprise," "include," and "have" are open-ended. That is, when a certain structure is included, other structures other than that structure may or may not be included.
[0044] In addition, when geometric terms and expressions indicating positional or directional relationships are used in this specification, such as "parallel," "orthogonal," "oblique at 45°," "coaxial," and "along," these terms allow for manufacturing errors or slight variations. When terms such as "upper" and "lower" are used in this specification to indicate relative positional relationships, these terms are intended to indicate a relative positional relationship in a single state. The relative positional relationship can be reversed or rotated to any angle depending on the installation orientation of each mechanism (for example, by turning the entire mechanism upside down).
[0045] In this specification, the term "battery" is not limited to lithium-ion batteries and may include other batteries such as nickel-metal hydride batteries and sodium-ion batteries. In this specification, the term "electrode" may be collectively referred to as a positive electrode and a negative electrode. Furthermore, the term "electrode plate" may be collectively referred to as a positive electrode plate and a negative electrode plate.
[0046] (Overall structure of the battery)
[0047] Figure 1 It is a front view of the secondary battery 1 according to this embodiment. Figures 2 to 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.
[0048] The secondary battery 1 can be mounted on a battery 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 use.
[0049] like Figures 1 to 5 As shown, the secondary battery 1 includes an exterior body 100, an electrode body 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).
[0050] In this application specification, there is Figures 1 to 5The X-axis direction (first direction) shown is called the "width direction" of the secondary battery 1 or the shell body 110, and similarly, the Y-axis direction (second direction) is called the "thickness direction" of the secondary battery 1 or the shell body 110, and similarly, the Z-axis direction (third direction) is called the "height direction" of the secondary battery 1 or the shell body 110.
[0051] When constructing a battery pack containing secondary batteries 1, multiple secondary batteries 1 are stacked in their thickness direction. The stacked secondary batteries 1 can be constrained in the stacking direction (Y-axis direction) by a constraining member to form a battery module, or the battery pack can be directly supported on the side of the battery pack casing without using a constraining member.
[0052] The case body 110 is formed of a cylindrical member, preferably a rectangular cylindrical member. This provides a rectangular secondary battery 1. The case body 110 is made of metal. Specifically, the case body 110 is formed of aluminum, an aluminum alloy, iron, or an iron alloy.
[0053] like Figure 1 、 Figure 2 As shown in FIG. 1 , sealing plates 121 and 122 are provided at both ends of the housing body. The housing body 110 is formed by, for example, placing the ends of the plate-like members that have been bent in contact with each other (at Figure 2 The corners of the "square tube shape" may also have an R shape.
[0054] In the present embodiment, the shell body 110 is formed in the width direction (X-axis direction) of the secondary battery 1 to be longer than the thickness direction (Y-axis direction) and the height direction (Z-axis direction) of the secondary battery 1. The dimension (width) of the shell body 110 in the X-axis direction is preferably more than 30 cm. Thus, a relatively large (high-capacity) secondary battery 1 can be constructed. The dimension (height) of the shell body 110 in the Z-axis 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 constructed, for example, to improve the mountability on a vehicle.
[0055] like Figure 3 As shown, an opening 111 (first opening) is provided at one end of the housing body 110. The opening 111 is sealed by a sealing plate 121. The sealing plate 121 is provided with a negative electrode terminal 131 (first electrode terminal), a liquid injection hole 141, and an exhaust valve 151. The positions of the negative electrode terminal 131, the liquid injection hole 141, and the exhaust valve 151 can be changed as appropriate. The opening 111 and the sealing plate 121 have a roughly rectangular shape with the Y-axis direction being the short side direction and the Z-axis direction being the long side direction.
[0056] like Figure 4 As shown, an opening 112 (second opening) is provided at the other end of the housing body 110. The opening 112 is sealed by a sealing plate 122. The sealing plate 122 is provided with a positive electrode terminal 132 (second electrode terminal), a liquid injection hole 142, and an exhaust valve 152. The positions of the positive electrode terminal 132, the liquid injection hole 142, and the exhaust valve 152 can be changed as appropriate. The opening 112 and the sealing plate 122 have a roughly rectangular shape with the Y-axis direction being the short side direction and the Z-axis direction being the long side direction.
[0057] The sealing plates 121 and 122 are made of metal. Specifically, the sealing plates 121 and 122 are made of aluminum, aluminum alloy, iron, iron alloy, or the like.
[0058] The negative electrode terminal 131 is electrically connected to the negative electrode of the electrode body 200 . The positive electrode terminal 132 is electrically connected to the positive electrode of the electrode body 200 .
[0059] The negative electrode terminal 131 is made of a conductive material (more specifically, a metal), such as copper or a copper alloy. A portion or layer made of aluminum or an aluminum alloy may be provided on the outer surface of the negative electrode terminal 131 .
[0060] The positive electrode terminal 132 is made of a conductive material (more specifically, metal), and can be made of, for example, aluminum or an aluminum alloy.
[0061] The liquid injection holes 141 and 142 are sealed by a sealing member (not shown). As the sealing member, for example, a blind rivet or other metal member can be used.
[0062] The exhaust valves 151 and 152 rupture when the pressure in the exterior body 100 reaches a predetermined value or higher, thereby exhausting the gas in the exterior body 100 to the outside.
[0063] The electrode body 200 is a flat electrode body having a positive electrode plate and a negative electrode plate to be described later. Specifically, the electrode body 200 is a wound electrode body formed by winding a strip of positive electrode plate and a strip of 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 alternating a plurality of positive electrode plates and a plurality of negative electrode plates. The electrode body includes a plurality of positive electrode plates and a plurality of negative electrode plates, and the positive electrode sheets provided on each positive electrode plate may also be stacked to form a positive electrode sheet group, and the negative electrode sheets provided on each negative electrode plate may also be stacked to form a negative electrode sheet group.
[0064] like Figure 5 As shown, the outer casing 100 houses the electrode assembly 200. The electrode assembly 200 is housed in the outer casing 100 so that its winding axis is parallel to the X-axis direction.
[0065] Specifically, a single or multiple wound electrode bodies and an electrolyte solution (electrolyte) (not shown) are housed inside an insulating sheet 600 (described later) disposed within the outer casing 100. For example, a non-aqueous electrolyte solution can be used, wherein LiPF6 is dissolved at a concentration of 1.2 mol / L in a non-aqueous solvent consisting of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) mixed at a volume ratio (at 25°C) of 30:30:40. Alternatively, a solid electrolyte may be used in place of the electrolyte solution.
[0066] The electrode body 200 includes a negative electrode sheet group 210A (first electrode sheet group) disposed at the end (first end) on the sealing plate 121 side, and a positive electrode sheet group 220A (second electrode sheet group) disposed at the end (second end) on the sealing plate 122 side. The negative electrode sheet group 210A and the positive electrode sheet group 220A are connected to the negative electrode and the positive electrode of the electrode body 200, respectively. The negative electrode sheet group 210A and the positive electrode sheet group 220A are formed so as to protrude from the main body of the electrode body 200 (the portion where the positive electrode plate and the negative electrode plate are stacked with separators) toward the sealing plates 121 and 122, respectively.
[0067] 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 formed of a plate-shaped member. The electrode assembly 200 is electrically connected to the negative electrode terminal 131 and the positive electrode terminal 132 via the current collector 300 .
[0068] The negative electrode current collector 310 is disposed on the sealing plate 121 via a resin insulating member. The negative electrode current collector 310 is electrically connected to the negative electrode sheet assembly 210A and the negative electrode terminal 131. The negative electrode current collector 310 is made of a conductive material (more specifically, a metal), such as copper or a copper alloy.
[0069] The positive electrode current collector 320 is arranged on the sealing plate 122 via a resin insulating member 420. The positive electrode current collector 320 is electrically connected to the positive electrode sheet group 220A and the positive terminal 132. The positive electrode current collector 320 is made of a conductive material (more specifically, a metal), for example, aluminum or an aluminum alloy. In addition, the positive electrode sheet group 220A can also be electrically connected to the sealing plate 122 directly or via the positive electrode current collector 320. In this case, the sealing plate 122 can also serve as the positive terminal 132.
[0070] (Structure of Electrode Body 200)
[0071] Figure 6 2 is a front view showing a negative electrode original plate 210S before forming the negative electrode plate 210 (first electrode). Figure 7 yes Figure 6The negative electrode original plate 210S is shown in the VII-VII cross-sectional view. Figure 8 1 is a front view showing a negative electrode plate 210 formed from a negative electrode original plate 210S.
[0072] 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.
[0073] A negative electrode active material layer 212 is formed on the negative electrode core 211 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.
[0074] 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 becomes approximately 98:1:1.
[0075] 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 active material layer 212 is compressed to form the negative electrode original plate 210S, which includes 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 using laser processing, die processing, or tooling using energy beam irradiation.
[0076] like Figure 8 As shown, at one end portion in the width direction of the negative electrode plate 210 formed from the negative electrode original plate 210S, a plurality of negative electrode sheets 210B composed of a negative electrode core 211 are provided. When the negative electrode plate 210 is wound, the plurality of negative electrode sheets 210B are stacked to form a negative electrode sheet group 210A. The positions of the plurality of negative electrode sheets 210B and the length of the protruding direction are appropriately adjusted in consideration of the state in which the negative electrode sheet group 210A is connected to the negative electrode collector 310. In addition, the shape of the negative electrode sheet 210B is not limited to Figure 8 The shape illustrated in .
[0077] Figure 9 2 is a front view showing the positive electrode original plate 220S before forming the positive electrode plate 220 (second electrode). Figure 10 yes Figure 9 The XX cross-sectional view of the positive electrode original plate 220S shown in FIG. Figure 111 is a front view showing a positive electrode plate 220 formed of a positive electrode original plate 220S.
[0078] The positive electrode plate 220 is manufactured by processing the positive electrode original plate 220S. Figure 9 and Figure 10 As shown, 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.
[0079] A positive electrode active material layer 222 is formed on the positive electrode core 221 except for one end portion of both surfaces. The positive electrode active material layer 222 is formed on the positive electrode core 221 by applying a positive electrode active material layer slurry using a die coater.
[0080] 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 becomes approximately 97.5:1:1.5.
[0081] The positive electrode protective layer 223 is in contact with the positive electrode core 221 and is formed on one end portion 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 using a die coater. The positive electrode protective layer 223 has a greater resistance than the positive electrode active material layer 222.
[0082] 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 approximately 83:3:14.
[0083] The positive electrode core 221 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 222 and the positive electrode protective layer 223. Furthermore, the positive electrode active material layer 222 is compressed to form the 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, tooling, or the like.
[0084] like Figure 11As shown, at one end portion in the width direction of the positive electrode plate 220 formed from the positive electrode original plate 220S, a plurality of positive electrode sheets 220B formed from the positive electrode core 221 are provided. When the positive electrode plate 220 is wound, the plurality of positive electrode sheets 220B are stacked to form a positive electrode sheet group 220A. The positions of the plurality of positive electrode sheets 220B and the length of the protruding direction are appropriately adjusted in consideration of the state in which the positive electrode sheet group 220A is connected to the positive electrode collector 320. In addition, the shape of the positive electrode sheet 220B is not limited to Figure 11 The shape illustrated in .
[0085] A positive electrode protection layer 223 is provided at the root portion of each of the plurality of positive electrode sheets 220B. The positive electrode protection layer 223 does not necessarily need to be provided at the root portion of the positive electrode sheet 220B.
[0086] In a typical example, the thickness of the negative electrode sheet 210B (one sheet) is smaller than the thickness of the positive electrode sheet 220B (one sheet). In this case, the thickness of the negative electrode sheet group 210A is smaller than the thickness of the positive electrode sheet group 220A.
[0087] (Connection Structure between Electrode Body 200 and Current Collector 300)
[0088] Figure 12 FIG. 2 is a diagram showing the electrode body 200 and the current collector 300 taken out of the secondary battery 1. Figure 12 As shown in FIG, the electrode body 200 is formed by stacking two electrode bodies 201 and 202, each of which is a wound electrode body. Figure 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.
[0089] The negative electrode sheet assembly 210A is joined to the negative electrode current collector 310 at a joint 310A, and the positive electrode sheet assembly 220A is joined to the positive electrode current collector 320 at a joint 320A. The joints 310A and 320A can be formed, for example, by ultrasonic welding, resistance welding, laser welding, riveting, or the like. The joints 310A and 320A form conductive paths between the negative electrode sheet assembly 210A and the positive electrode sheet assembly 220A and the negative electrode terminal 131 and the positive electrode terminal 132.
[0090] (Connection Structure between Electrode Body 200 and Negative Electrode Current Collector 310)
[0091] Figure 13 This figure shows the connection structure between the negative electrode sheet group 210A and the negative electrode current collector 310 . Figure 14 、 Figure 15 They are Figure 13 The front view and cross-sectional view of the connection structure shown.
[0092] like Figures 13 to 15 As shown, the negative electrode current collector 310 is connected to the negative electrode terminal 131 between the electrode assembly 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 .
[0093] The negative electrode sheet assembly 210A is joined to the first conductive member 311 of the negative electrode current collector 310 at a joint 310A. The first conductive member 311 is connected to the second conductive member 312 at a joint 313. The joint 313 can be formed by, for example, ultrasonic welding, resistance welding, laser welding, or riveting.
[0094] 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.
[0095] The negative terminal 131 is attached to the sealing plate 121 via a resin insulating member 410A. The negative terminal 131 is provided so as to be exposed on the outside of the sealing plate 121 and to reach the second conductive member 312 of the negative electrode current collector 310 provided on the inner surface side of the sealing plate 121. The negative terminal 131 and the second conductive member 312 can be connected by, for example, ultrasonic bonding, resistance welding, laser welding, riveting, or the like. In this embodiment, a through hole is provided in the second conductive member 312, the negative terminal 131 is inserted into the through hole, and after the negative terminal 131 is riveted to the second conductive member 312, the riveted portion and the second conductive member 312 are welded at the joint 131A, thereby connecting the negative terminal 131 to the second conductive member 312.
[0096] As the order for assembling the components, first, the negative electrode terminal 131 and the second conductive component 312 are attached to the sealing plate 121 along with the insulating components 410 and 410A. Next, the first conductive component 311, which is connected to the electrode body 200, is attached to the second conductive component 312. At this time, the first conductive component 311 is positioned on the insulating component 410 so that a portion of the first conductive component 311 overlaps with the second conductive component 312. Next, the first conductive component 311 and the second conductive component 312 are welded together at the joint 313. Alternatively, the insulating components 410 and 410A may be formed from a single component.
[0097] The negative electrode terminal 131 may also be electrically connected to the sealing plate 121 . In addition, the sealing plate 121 may also function as the negative electrode terminal 131 .
[0098] In addition, Figures 13 to 15 , the negative electrode current collector 310 is exemplified as being composed of two members (the first conductive member 311 and the second conductive member 312 ), but the negative electrode current collector 310 may also be composed of a single member.
[0099] (Step of Inserting Electrode Body 200)
[0100] Figure 16 1 is a diagram showing the process of inserting the electrode body 200 into the case body 110. Figure 16 As shown, a resin insulating sheet 600 (electrode body holder) is arranged between the electrode body 200 and the case body 110 .
[0101] The insulating sheet 600 may be made of, for example, resin. More specifically, the insulating sheet 600 may be made of, for example, polypropylene (PP), polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polyimide (PI), or polyolefin (PO).
[0102] The insulating sheet 600 does not necessarily need to cover the entire surface of the electrode body 200. Preferably, the insulating sheet 600 covers at least 50% of the outer surface of the electrode body, and more preferably at least 70%. Preferably, the insulating sheet 600 covers the entirety of at least four of the six surfaces of the substantially rectangular (flat) electrode body 200, excluding the two surfaces each having the negative electrode sheet assembly 210A and the positive electrode sheet assembly 220A formed thereon.
[0103] Figure 17 This is a diagram showing a step of placing the separator 510 between the sealing plate 121 and the electrode assembly 200 . Figure 18 It is a cross-sectional view showing a state where the separator 510 is arranged between the sealing plate 121 and the electrode body 200 .
[0104] like Figure 17 、 Figure 18 As shown, the negative electrode sheet assembly 210A extending from the electrode assembly 200 toward the sealing plate 121 is bent from the center of the sealing plate 121 in the Y-axis direction toward the end, and then folded back toward the center. A separator 510 is provided to accommodate the bent negative electrode sheet assembly 210A (the bent portion).
[0105] The spacer 510 includes a first spacer 511 and a second spacer 512. The first spacer 511 and the second spacer 512 are each slid along the Y-axis direction from the end toward the center of the sealing plate 121 to engage with each other. This secures the spacer 510 to the first sealing plate 121 via the insulating member 410, increasing the stability of the spacer 510's position.
[0106] like Figure 18 As shown, the separator 510 forms an internal space for accommodating the negative electrode current collector 310, and the front end portion of the negative electrode sheet group 210A is also accommodated in the internal space of the separator 510. The separator 510 has a hole for allowing the negative electrode sheet group 210A to pass through.
[0107] The material of the separator 510 is not particularly limited, but an insulating material such as resin is preferably used. More specifically, a polyolefin (PO) sheet is preferably used. Alternatively, an insulating sheet 600 may be interposed between the separator 510 and the electrode assembly 200 .
[0108] Refer again Figure 16 In the manufacturing method of the secondary battery 1 of this embodiment, after the positive electrode sheet group 220A is joined to the first conductive member 321 of the positive electrode collector 320 , the electrode body 200 is inserted into the case body 110 from the end side on the positive electrode sheet group 220A side.
[0109] When the electrode assembly 200 is inserted into the case body 110 through the opening 111, the positive electrode sheet assembly 220A located at the front side may be deformed undesirably. In contrast, by inserting the electrode assembly 200 into the case body 110 after bonding the positive electrode sheet assembly 220A to the first conductive member 321 of the positive electrode current collector 320, undesirable deformation of the positive electrode sheet assembly 220A can be suppressed. As a result, a highly reliable secondary battery 1 can be manufactured stably and efficiently.
[0110] In addition, Figure 16 In the example, the electrode body 200 is inserted into the case body 110 while being covered by the insulating sheet 600 . This can prevent damage to the electrode body 200 caused by inserting the electrode body 200 into the case body 110 .
[0111] In addition, Figure 16 In the example, after the negative electrode terminal 131 is electrically connected to the negative electrode sheet assembly 210A, the electrode assembly 200 is inserted into the case body 110 from the end side on the positive electrode sheet assembly 220A side through the opening 111. When the negative electrode terminal 131 attached to the sealing plate 121 is electrically connected to the negative electrode sheet assembly 210A after the electrode assembly 200 is inserted into the case body 110, the negative electrode sheet assembly 210A is required to have a length sufficient for the negative electrode sheet assembly 210A of the electrode assembly 200 housed in the case body 110 to protrude outside the case body 110. By electrically connecting the negative electrode terminal 131 attached to the sealing plate 121 to the negative electrode sheet assembly 210A before inserting the electrode assembly 200 into the case body 110, the length of the negative electrode sheet assembly 210A can be shortened compared to a case where the negative electrode sheet assembly 210A is installed 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.
[0112] During the insertion process of the electrode body 200, the case body 110 can be held at a predetermined angle. As one example, the electrode body 200 is preferably inserted while the case body 110 is held so that the X-axis direction (the width direction of the case body 110) intersects the horizontal direction at an angle of approximately ±45° or less. For example, the case body 110 can be tilted so that the upper end of the opening 111, into which the electrode body 200 is inserted, is located vertically above the upper end of the opening 112.
[0113] The step of inserting the electrode body 200 is not limited to a method of pressing the electrode body 200 from the opening 111 side, and may be a method of pulling the electrode body 200 from the opening 112 side, for example.
[0114] (Connection Structure between Electrode Body 200 and Positive Electrode Current Collector 320)
[0115] Figure 19 This is a diagram showing the connection structure between the positive electrode sheet group 220A and the positive electrode current collector 320 . Figure 20 yes Figure 19 A cross-sectional view of the connection structure shown.
[0116] like Figure 19 and Figure 20 As shown, the positive electrode current collector 320 is provided on the inner surface 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 member) and a second conductive member 322 (second member). 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 of the sealing plate 122 via a resin insulating member 420.
[0117] The first conductive member 321 has a step portion 321A. The step portion 321A extends along the longitudinal direction (Z-axis direction) of the rectangular sealing plate 122. Figure 20 As shown, on one side relative to the step portion 321A ( Figure 20 In the region (the first region) on the left side of the step portion 321A, the first conductive component 321 is provided along the sealing plate 122 and is joined to the positive electrode assembly 220A (joining portion 320A). Figure 20 In the region (the second region) on the right side of the electrode, the first conductive member 321 is provided so as to overlap with the second conductive member 322. These structures are also the same on the negative electrode side (see Figures 13 to 15 ).
[0118] exist Figure 19 and Figure 20, the shape of the positive electrode sheet assembly 220A before being bent is shown. However, in the completed secondary battery 1, the positive electrode sheet assembly 220A is housed in the case body 110 in a bent state. It is preferable to bend (reform) the positive electrode sheet assembly 220A to a state close to the final shape before housing the electrode assembly 200 in the case body 110.
[0119] The positive electrode assembly 220A is joined to the first conductive member 321 of the positive electrode current collector 320 at a joint 320A. The first conductive member 321 is connected to the second conductive member 322 at a joint 323. The joint 323 can be formed by, for example, ultrasonic welding, resistance welding, laser welding, or riveting.
[0120] The positive terminal 132 is mounted on the sealing plate 122 via an insulating member 420A made of resin. The positive terminal 132 is configured to be exposed on the outside of the sealing plate 122 and to reach the second conductive member 322 of the positive electrode collector 320 provided on the inner surface side of the sealing plate 122. The positive terminal 132 and the second conductive member 322 can be connected by, for example, ultrasonic bonding, resistance welding, laser welding, riveting, etc. In this embodiment, a through hole is provided in the second conductive member 322, the positive terminal 132 is inserted into the through hole, and after the positive terminal 132 is riveted to the second conductive member 322, the riveted portion and the second conductive member 322 are welded at the joint 132A, thereby connecting the positive terminal 132 to the second conductive member 322.
[0121] The order for assembling the components is as follows: first, the positive electrode terminal 132 and the second conductive component 322 are attached to the sealing plate 122 along with the insulating components 420 and 420A. Next, the first conductive component 321, which is connected to the electrode body 200, is attached to the second conductive component 322. At this time, the first conductive component 321 is positioned on the insulating component 420 so that a portion of the first conductive component 321 overlaps with the second conductive component 322. Next, the first conductive component 321 and the second conductive component 322 are welded together at the joint 323. Alternatively, the insulating components 420 and 420A may be formed from a single component.
[0122] The positive electrode terminal 132 may also be electrically connected to the sealing plate 122 . In addition, the sealing plate 122 may also function as the positive electrode terminal 132 .
[0123] In addition, Figure 19 and Figure 20 , the positive electrode current collector 320 is exemplified as being composed of two members (the first conductive member 321 and the second conductive member 322 ), but the positive electrode current collector 320 may also be composed of a single member.
[0124] (Manufacturing Process of Secondary Battery 1)
[0125] Figure 21 1 is a flow chart showing each step of the manufacturing method of the secondary battery 1. Figure 21 As shown, in S10, the case body 110 is prepared. Next, in S20, the electrode body 200 is manufactured. In S30, the electrode terminals provided on the sealing plates 121 and 122 are electrically connected to the electrode sheet group of the electrode body 200. Figure 21 In the example of , first, the negative electrode terminal 131 is electrically connected to the negative electrode sheet group 210A ( S31 ), and then the positive electrode terminal 132 is electrically connected to the positive electrode sheet group 220A ( S32 ).
[0126] To electrically connect the positive electrode terminal 132 to the positive electrode sheet assembly 220A, the first conductive member 321 of the positive electrode current collector 320 is first joined to the positive electrode sheet assembly 220A ( S32A). The electrode assembly 200 is then inserted into the case body 110 ( S40 ). After the electrode assembly 200 is inserted into the case body 110, the first conductive member 311 and the second conductive member 312 are joined to electrically connect the positive electrode terminal 132 to the positive electrode sheet assembly 220A ( S32B).
[0127] After the electrode terminals are connected to the electrode sheet assembly ( S30 ) and the electrode body 200 is inserted ( S40 ), the openings 111 and 112 are sealed ( S50 ) by sealing plates 121 and 122 . The sealing process using sealing plates 121 and 122 is performed, for example, by laser welding.
[0128] In this technology, the order of connecting the negative terminal 131 to the negative electrode sheet group 210A (S31), connecting the positive terminal 132 to the positive electrode sheet group 220A (S32), and inserting the electrode body 200 (S40) is not limited to Figure 21 For example, there is also a case where the negative terminal 131 is connected to the negative electrode sheet group 210A (S31) after the positive electrode terminal 132 is connected to the positive electrode sheet group 220A (S32).
[0129] exist Figure 21 In the example, after the step (S51) of sealing the opening 111 with the sealing plate 121 on the negative electrode side is performed, the step (S52) of sealing the opening 112 with the sealing plate 122 on the positive electrode side is performed. However, the step (S51) of sealing the opening 111 with the sealing plate 121 may be performed after the step (S52) of sealing the opening 112 with the sealing plate 122. Furthermore, at least a portion of the steps (S51, S52) of sealing with the sealing plates 121 and 122 may be performed simultaneously.
[0130] (summary)
[0131] The secondary battery 1 and the manufacturing method thereof according to the present embodiment can be summarized as follows.
[0132] like Figure 21 As shown, the manufacturing method of the secondary battery 1 comprises: a step (S10) of preparing a shell body 110 having an opening 111 and an opening 112 opposite to the opening 111; a step (S20) of forming an electrode body 200, wherein the electrode body 200 includes a negative electrode plate 210 and a positive electrode plate 220, and a negative electrode sheet group 210A at one end of the electrode body 200, the negative electrode sheet group 210A including a negative electrode sheet 210B electrically connected to the negative electrode plate 210, and a positive electrode sheet 220 at the other end of the electrode body 200. The end portion has a positive electrode sheet group 220A, which includes a positive electrode sheet 220B electrically connected to the positive electrode plate 220; a process (S30) of electrically connecting the electrode terminals provided on the sealing plates 121 and 122 to the electrode sheet group of the electrode body 200; a process (S40) of inserting the electrode body 200 from the end side of the positive electrode sheet group 220A side into the shell body 110 through the opening 111; a process (S50) of sealing the openings 111 and 112 respectively by the sealing plates 121 and 122. Here, the positive electrode sheet group 220A is joined to the first conductive component 321 of the positive electrode collector 320 (S32A), and then the electrode body 200 is inserted into the shell body 110 from the end side of the positive electrode sheet group 220A through the opening 111 (S40), and the positive terminal 132 provided on the sealing plate 122 is electrically connected to the positive electrode sheet group 220A (S32B).
[0133] In one example of a method for manufacturing the secondary battery 1 , the positive electrode terminal 132 and the positive electrode sheet group 220A are electrically connected by joining the first conductive member 321 to the second conductive member 322 provided on the sealing plate 122 .
[0134] In one example method for manufacturing a secondary battery 1, the negative terminal 131 is electrically connected to the negative electrode sheet group 210A by joining the negative electrode sheet group 210A to the first conductive component 311 (third conductive component) of the negative electrode collector 310, and then joining the first conductive component 311 (third conductive component) to the second conductive component 312 (fourth conductive component) provided on the sealing plate 121.
[0135] In one example of a method for manufacturing the secondary battery 1 , the electrode body 200 before being inserted into the case body 110 may be covered with the insulating sheet 600 . However, in the present technology, the insulating sheet 600 covering the electrode body 200 is not essential.
[0136] The secondary battery 1 of this embodiment comprises: an electrode body 200, which is provided with a negative electrode sheet group 210A on the sealing plate 121 side and a positive electrode sheet group 220A on the sealing plate 122 side; an outer body 100 (shell), which houses the electrode body 200; a negative terminal 131 (first electrode terminal) and a positive terminal 132 (second electrode terminal), which are provided on the outer body 100; a negative electrode collector 310 (first current collector), which is housed in the outer body 100 and electrically connects the negative electrode sheet group 210A to the negative terminal 131; and a positive electrode collector 320 (second current collector), which is housed in the outer body 100 and electrically connects the positive electrode sheet group 220A to the positive terminal 132.
[0137] The negative electrode sheet assembly 210A and the positive electrode sheet assembly 220A each have a curved portion. The negative electrode sheet assembly 210A and the positive electrode sheet assembly 220A are joined to the negative electrode collector 310 and the positive electrode collector 320, respectively, at joining portions 310A and 320A located toward the front end of the curved portion. In the region where the joining portions 310A and 320A are located, the first conductive members 311 and 321 of the negative electrode collector 310 and the positive electrode collector 320 are positioned along the sealing plates 121 and 122.
[0138] (Function and Effect)
[0139] According to the secondary battery 1 of this embodiment, by inserting the electrode body 200 into the shell body 110 having mutually opposing openings 111 and 112 and providing the negative terminal 131 and the positive terminal 132 on the sealing plates 121 and 122 for sealing the openings 111 and 112 respectively, the height of the secondary battery 1 can be reduced and the mountability of the secondary battery 1 on the vehicle can be improved.
[0140] Furthermore, by arranging the regions where the joints 310A and 320A of the negative electrode current collector 310 and the positive electrode current collector 320 are joined to the negative electrode sheet group 210A and the positive electrode sheet group 220A along the sealing plates 121 and 122 , respectively, the energy density of the secondary battery 1 can be increased.
[0141] According to the method for manufacturing the secondary battery 1 of this embodiment, the positive electrode sheet assembly 220A is joined to the first conductive member 321 ( S32A) before the step ( S40 ) of inserting the electrode assembly 200 into the case body 110 . Therefore, the electrode assembly 200 can be inserted while suppressing undesirable deformation (undesirable bending, etc.) of the positive electrode sheet assembly 220A located at the leading end of the electrode assembly 200 in the insertion direction. Consequently, the secondary battery 1 can be manufactured stably and efficiently.
[0142] According to the secondary battery 1 of this embodiment, since the positive electrode sheet assembly 220A is joined to the first conductive member 321 included in the positive electrode current collector 320 , the manufacturing method of joining the positive electrode sheet assembly 220A ( S32A) before the electrode assembly 200 insertion step ( S40 ) can be easily implemented.
[0143] As described above, according to the secondary battery 1 and the manufacturing method thereof of the present embodiment, a secondary battery having high energy density and high reliability can be manufactured stably and efficiently.
[0144] While the embodiments of the present invention have been described, the embodiments disclosed herein are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is indicated by the claims, and all modifications within the meaning and scope of the claims are intended to be encompassed.
Claims
1. A method for manufacturing a secondary battery, It is characterized in that The following processes are available, namely: A step of preparing a housing body having a first opening and a second opening opposite to the first opening; A step of forming an electrode body, wherein the electrode body includes a first electrode and a second electrode having a polarity different from that of the first electrode, wherein the electrode body has a first electrode sheet group electrically connected to the first electrode at a first end thereof, and has a second electrode sheet group electrically connected to the second electrode at a second end located on the opposite side to the first end; A step of electrically connecting a first electrode terminal provided on a first sealing plate to the first electrode sheet group; The step of bonding the second electrode sheet group to the first conductive member; After the second electrode sheet group is joined to the first conductive member, the electrode body is inserted into the housing body from the side where the second end portion is located through the first opening; A step of electrically connecting a second electrode terminal provided on a second sealing plate to the second electrode sheet group; After electrically connecting the first electrode terminal to the first electrode sheet group, sealing the first opening with the first sealing plate; and A step of sealing the second opening with the second sealing plate after the second electrode terminal is electrically connected to the second electrode sheet group.
2. The method for manufacturing a secondary battery according to claim 1, It is characterized in that The step of electrically connecting the second electrode terminal to the second electrode sheet group includes electrically connecting the first conductive member to the second electrode terminal after inserting the electrode body into the case body.
3. The method for manufacturing a secondary battery according to claim 2, It is characterized in that Electrically connecting the first conductive member to the second electrode terminal includes bonding the first conductive member to a second conductive member attached to the second sealing plate.
4. The method for manufacturing a secondary battery according to claim 1, It is characterized in that The step of electrically connecting the first electrode terminal to the first electrode sheet group includes bonding the first electrode sheet group to a third conductive member before inserting the electrode body into the case body.
5. The method for manufacturing a secondary battery according to claim 4, It is characterized in that The step of electrically connecting the first electrode terminal to the first electrode sheet group includes electrically connecting the third conductive member to the first electrode terminal before inserting the electrode body into the case body.
6. The method for manufacturing a secondary battery according to claim 5, It is characterized in that Electrically connecting the third conductive member to the first electrode terminal includes bonding the third conductive member to a fourth conductive member attached to the first sealing plate.
7. The method for producing a secondary battery according to any one of claims 4 to 6, It is characterized in that The first electrode sheet group has a bent portion, and a portion of the first electrode sheet group closer to the front end than the bent portion is bonded to the third conductive member. A region of the third conductive member that is bonded to the first electrode sheet group is disposed along the first sealing plate.
8. The method for producing a secondary battery according to any one of claims 1 to 6, It is characterized in that The second electrode sheet group has a bent portion, and a portion of the second electrode sheet group closer to the front end than the bent portion is bonded to the first conductive member. A region of the first conductive member that is bonded to the second electrode sheet group is disposed along the second sealing plate.
9. The method for producing a secondary battery according to any one of claims 1 to 6, It is characterized in that The method further includes covering the electrode body before being inserted into the case body with an insulating electrode body holder.
10. A secondary battery, It is characterized in that have: An electrode body, the electrode body comprising a first electrode and a second electrode having a polarity different from that of the first electrode, the electrode body having a first electrode sheet group electrically connected to the first electrode at a first end thereof, and a second electrode sheet group electrically connected to the second electrode at a second end located on the opposite side to the first end; a shell, the shell accommodating the electrode body; a first electrode terminal and a second electrode terminal, which are disposed on the housing; a first current collector housed in the housing and electrically connecting the first electrode and the first electrode terminal; and a second current collector housed in the housing and electrically connecting the second electrode to the second electrode terminal; The housing comprises: a housing body having a first opening and a second opening opposite to the first opening; a first sealing plate for sealing the first opening and provided with the first electrode terminal; and a second sealing plate for sealing the second opening and provided with the second electrode terminal, The first electrode sheet group has a first bent portion, and a portion of the first electrode sheet group closer to the front end than the first bent portion is joined to the first current collector. The second electrode sheet group has a second bent portion, and a portion of the second electrode sheet group closer to the front end than the second bent portion is joined to the second current collector. The region of the first current collector that is bonded to the first electrode sheet group is arranged along the first sealing plate. A region of the second current collector that is joined to the second electrode sheet group is arranged along the second sealing plate.
11. The secondary battery according to claim 10, It is characterized in that The first sealing plate has a substantially 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 member joined to the first electrode sheet group and a second member electrically connecting the first member to the first electrode terminal. The first component includes a first region, a second region, and a step portion formed between the first region and the second region along the pair of long sides. The first electrode sheet group is joined to the first region, and the second region is arranged to overlap with the second member.
12. The secondary battery according to claim 10, It is characterized in that The second sealing plate has a substantially 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 member joined to the second electrode sheet group and a second member electrically connecting the first member to the second electrode terminal. The first component includes a first region, a second region, and a step portion formed between the first region and the second region along the pair of long sides. The second electrode sheet group is joined to the first region, and the second region is arranged to overlap with the second member.