Secondary battery manufacturing method and secondary battery

Abstract

To improve the energy density of a secondary battery and stably manufacture the secondary battery.SOLUTION: A manufacturing method for a secondary battery includes the steps of: manufacturing a first electrode body 201 and a second electrode body 202, and then in a state where the first electrode body 201 is disposed on one side of a second current collector 420 and the second electrode body 202 is disposed on the other side of the second current collector 420, electrically connecting a second electrode tab 250 and a fourth electrode tab 280 to the second current collector 420; and bonding the second electrode tab 250 and the fourth electrode tab 280, and then bending the second electrode tab 250 and the fourth electrode tab 280 so that the first electrode tab 220 and the third electrode tab 270 face each other, to overlap the first electrode body 201 and the second electrode body 202 with each other.SELECTED DRAWING: Figure 16

Description

[Technical Field]

[0001] The present technology relates to a method for manufacturing a secondary battery and a secondary battery. [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] In the secondary battery described in Patent Document 1, there is room for improvement in the energy density and for stable production of secondary batteries.

[0005] The present technology has been made to solve the above-mentioned problems, and aims to provide a method for manufacturing a secondary battery that can improve energy density and be stably manufactured, and a secondary battery. [Means for solving the problem]

[0006] The present technology provides the following method for manufacturing a secondary battery. [1] a first electrode body and a second electrode body, each of which includes a first electrode and a second electrode having a polarity different from that of the first electrode; a case that houses the first electrode body and the second electrode body; a first electrode terminal electrically connected to the first electrode, the first electrode body includes a first electrode tab disposed at a first end and electrically connected to the first electrode, and a second electrode tab disposed at a second end and electrically connected to the second electrode; the second electrode body includes a third electrode tab disposed at a third end and electrically connected to the first electrode, and a fourth electrode tab disposed at a fourth end and electrically connected to the second electrode; the first electrode tab is joined to a first current collector; the second electrode tab and the fourth electrode tab are joined to a second current collector; the third electrode tab is joined to a third current collector; A method for manufacturing a secondary battery, wherein the first current collector and the third current collector are configured as separate components, fabricating the first electrode body and the second electrode body; a step of joining the first electrode tab to the first current collector after fabricating the first electrode body and the second electrode body; a step of joining the third electrode tab to the third current collector after fabricating the first electrode body and the second electrode body; a step of electrically connecting the second electrode tab and the fourth electrode tab to the second current collector in a state in which the first electrode body is disposed on one side of the second current collector and the second electrode body is disposed on the other side of the second current collector after the first electrode body and the second electrode body are fabricated; a step of bending the second electrode tab and the fourth electrode tab after joining the second electrode tab and the fourth electrode tab to the second current collector, and overlapping the first electrode body and the second electrode body; and after overlapping the first electrode body and the second electrode body, electrically connecting the first current collector joined to the first electrode tab and the third current collector joined to the third electrode tab to the first electrode terminal. "Overlapping the first electrode body and the second electrode body" means that the first electrode body and the second electrode body may be directly overlapped, or another member may be placed between the first electrode body and the second electrode body. The first electrode body and the second electrode body may or may not be fixed with tape or the like. Furthermore, the first electrode body, the second current collector, and the second electrode body do not have to be arranged in a straight line in one direction, and the first electrode body or the second electrode body may be tilted in one direction relative to the second current collector. [2] the case includes a case body having a first opening and a first sealing plate that seals the first opening, the first sealing plate is provided with the first electrode terminal, [1] A method for manufacturing a secondary battery according to the present invention, comprising the step of stacking the first electrode body and the second electrode body, and then inserting the first electrode body and the second electrode body, with the second current collector side first, into the case body through the first opening. [3] the case body has a second opening at an end opposite to the first opening, the case includes a second sealing plate that seals the second opening, a second electrode terminal electrically connected to the second electrode is provided on the second sealing plate; [2] The method for manufacturing a secondary battery according to [2], further comprising a step of electrically connecting the second current collector to the second electrode terminal after inserting the first electrode body and the second electrode body into the case body. [4] The method for manufacturing a secondary battery according to any one of [1] to [3], wherein the first electrode tab and the third electrode tab are curved in opposite directions so that the tips located at the ends opposite to the side to which the first electrode is connected approach each other. [5] The method for manufacturing a secondary battery according to any one of [1] to [3], wherein each of the first electrode tab and the third electrode tab is curved in the same direction so that the tip portions located at the end opposite to the side to which the first electrode is connected face in the same direction. [6] The method for producing a secondary battery according to any one of [1] to [5], wherein the second current collector is constituted by one component.

[0007] The present technology provides the following method for manufacturing a secondary battery. [7] a first electrode body and a second electrode body, each of which includes a first electrode and a second electrode having a polarity different from that of the first electrode; a case that houses the first electrode body and the second electrode body; a first electrode terminal electrically connected to the first electrode, the first electrode body includes a first electrode tab disposed at a first end and electrically connected to the first electrode, and a second electrode tab disposed at a second end and electrically connected to the second electrode; the second electrode body includes a third electrode tab disposed at a third end and electrically connected to the first electrode, and a fourth electrode tab disposed at a fourth end and electrically connected to the second electrode; the first electrode body and the second electrode body are aligned in a thickness direction of the first electrode body and the second electrode body, the first electrode tab is joined to a first current collector; the second electrode tab and the fourth electrode tab are joined to a second current collector; the third electrode tab is joined to a third current collector; A secondary battery, wherein the first current collector and the third current collector are formed as separate parts. [8] the case includes a case body having a first opening and a first sealing plate that seals the first opening, The secondary battery according to [7], wherein the first sealing plate is provided with the first electrode terminal. [9] the case body has a second opening at an end opposite to the first opening, the case includes a second sealing plate that seals the second opening, The secondary battery according to [8], wherein the second sealing plate is provided with a second electrode terminal electrically connected to the second electrode.

[10] The secondary battery according to any one of [7] to [9], wherein the second electrode tab and the fourth electrode tab are curved in opposite directions so that the tips located at the ends opposite to the side to which the second electrode is connected approach each other.

[11] The secondary battery according to any one of [7] to

[10] , wherein the first electrode tab and the third electrode tab are curved in opposite directions so that the tips located at the ends opposite to the side to which the first electrode is connected approach each other.

[12] The secondary battery according to any one of [7] to

[10] , wherein each of the first electrode tab and the third electrode tab is curved in the same direction so that the tip portions located at the end opposite to the side to which the first electrode is connected face in the same direction.

[13] The secondary battery according to any one of [7] to

[12] , wherein the second current collector is constituted by one component. [Effects of the Invention]

[0008] According to the present technology, the energy density of a secondary battery can be improved and secondary batteries can be stably manufactured. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a front view showing a configuration of a secondary battery according to a first embodiment of the present technology. [Figure 2] 2 is a diagram showing the secondary battery shown in FIG. 1 as viewed from the direction of arrow II. [Figure 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. FIG. [Figure 5] 2 is a diagram showing the secondary battery shown in FIG. 1 as viewed from the direction of arrow V. FIG. [Figure 6] FIG. 2 is a front cross-sectional view of the secondary battery shown in FIG. [Figure 7] FIG. 2 is a front view showing a negative electrode blank before being formed into a negative electrode plate. [Figure 8] 8 is a cross-sectional view taken along the line VIII-VIII of the negative electrode plate shown in FIG. 7. [Figure 9] FIG. 2 is a front view showing a negative electrode plate formed from a negative electrode original plate. [Figure 10] FIG. 2 is a front view showing a positive electrode plate before it is formed into a positive electrode plate. [Figure 11] 11 is a cross-sectional view of the positive electrode plate taken along the line XI-XI in FIG. 10. [Figure 12] FIG. 2 is a front view showing a positive electrode plate formed from a positive electrode original plate. [Figure 13] 1. FIG. 2 is a cross-sectional view of the secondary battery shown in FIG. [Figure 14] 1. FIG. 2 is a cross-sectional view of the secondary battery shown in FIG. [Figure 15] 3 is a flowchart showing a method for manufacturing a secondary battery according to the first embodiment. [Figure 16] 1 is a perspective view showing a state before two electrode bodies included in the secondary battery according to Embodiment 1 are overlapped. [Figure 17] 17 is a cross-sectional view taken along the line XVII-XVII of the electrode body and current collector shown in FIG. 16. FIG. [Figure 18] FIG. 2 is a perspective view showing a state in which a holder and a spacer are attached to an electrode body. [Figure 19] FIG. 2 is a perspective view showing a state in which a first sealing plate is attached to a first current collector. [Figure 20] 20 is a cross-sectional view of the electrode body and current collector shown in FIG. 19 taken along the line XX-XX. [Figure 21] FIG. 2 is a perspective view showing a state in which an electrode body is being inserted into a case main body. [Figure 22] FIG. 10 is a perspective view showing a state in which a second sealing plate is attached to a second current collector. [Figure 23] 23 is a cross-sectional view taken along the line XXIII-XXIII of the electrode body and current collector shown in FIG. 22. [Figure 24] 1 is a perspective view showing the configuration of a secondary battery according to Embodiment 1. FIG. [Figure 25] FIG. 10 is a cross-sectional view showing the configuration of a secondary battery according to a second embodiment. [Figure 26] 10 is a plan view showing a state before two electrode bodies included in a secondary battery according to Embodiment 2 are overlapped. FIG. [Figure 27] 10 is a plan view showing a state before two electrode bodies included in a secondary battery according to Embodiment 3 are overlapped. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present technology will be described. Note that the same or corresponding parts are denoted by the same reference characters, and description thereof may not be repeated.

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

[0012] In this specification, the terms "comprise," "include," and "have" are open-ended. That is, when a certain feature is included, other features may or may not be included.

[0013] Furthermore, when geometric terms and terms expressing positional and directional relationships are used in this specification, such as "parallel," "orthogonal," "45° diagonal," "coaxial," and "along," 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 a single state, and the relative positional relationships can be reversed or rotated to any angle depending on the installation direction of each mechanism (for example, by turning the entire mechanism upside down).

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

[0015] In the drawings, the direction along the winding axis of the electrode body provided in the secondary battery is the X direction, the shorter side direction of the electrode body as viewed from the X direction is the Y direction, and the longer side direction of the electrode body as viewed from the X direction is the Z direction. Also, to make the invention easier to understand, the dimensions of each component in the drawings may be shown differently from the actual dimensions.

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

[0017] (Embodiment 1) (Overall battery configuration) Fig. 1 is a front view of a secondary battery 1 according to the present embodiment. Figs. 2 to 5 are views of the secondary battery 1 shown in Fig. 1 as viewed from the directions of arrows II, III, IV, and V, respectively. Fig. 6 is a front cross-sectional view of the secondary battery 1 shown in Fig. 1.

[0018] The secondary battery 1 can be mounted in an electric vehicle (BEV: Battery Electric Vehicle), a plug-in hybrid electric vehicle (PHEV: Plug-in Hybrid Electric Vehicle), a hybrid electric vehicle (HEV: Hybrid Electric Vehicle), etc. However, the use of the secondary battery 1 is not limited to being mounted in a vehicle.

[0019] 1 to 6, the secondary battery 1 includes a case 100, an electrode assembly 200, an electrode terminal 300, and a current collector 400. The case 100 includes a case body 110, a first sealing plate 120, and a second sealing plate 130.

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

[0021] The case body 110 is made of a cylindrical, preferably rectangular, member. This results in a rectangular secondary battery 1. The case body 110 is made of metal. Specifically, the case body 110 is made of aluminum, an aluminum alloy, iron, an iron alloy, or the like.

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

[0023] In this embodiment, the case body 110 is formed so that it is longer in the width direction (X direction) of the secondary battery 1 than in the thickness direction (Y direction) and height direction (Z direction) of the secondary battery 1. The dimension (width) of the case body 110 in the X direction is preferably about 30 cm or more. This allows for the construction of a relatively large (high-capacity) secondary battery 1. The dimension (height) of the case body 110 in the Z direction is preferably about 20 cm or less, more preferably about 15 cm or less, and even more preferably about 10 cm or less. This allows for the construction of a relatively low-height secondary battery 1, which improves, for example, the mountability in a vehicle.

[0024] The case main body 110 includes a pair of first side surface portions 111 and a pair of second side surface portions 112. The pair of first side surface portions 111 constitute part of the side surfaces of the case 100. The pair of second side surface portions 112 constitute the bottom surface portion and the top surface portion of the case 100. The pair of first side surface portions 111 and the pair of second side surface portions 112 are arranged to intersect with each other. The pair of first side surface portions 111 and the pair of second side surface portions 112 are connected at their respective ends. It is desirable that each of the pair of first side surface portions 111 has a larger area than each of the pair of second side surface portions 112.

[0025] 5, a gas release valve 150 is provided on one second side surface portion 112A of the pair of second side surface portions 112. The gas release valve 150 extends in the width direction (X direction) of the secondary battery 1. The gas release valve 150 extends in the X direction from the center of the case body 110 in the X direction but does not reach both ends. The gas release valve 150 can be modified as appropriate.

[0026] The thickness of the plate-like member in the gas release valve 150 is thinner than the thickness of the plate-like members of the case body 110 other than the gas release valve 150. As a result, when the pressure inside the case 100 reaches or exceeds a predetermined value, the gas release valve 150 breaks preferentially compared to other parts of the case body 110, and releases gas inside the case 100 to the outside.

[0027] 2, a joint 115 is formed on the other second side surface portion 112B of the pair of second side surface portions 112. The joint 115 extends in the width direction (X direction) of the secondary battery 1. At the joint 115, the edges of the plate-like members that make up the case body 110 are joined together.

[0028] 3, a first opening 113 is provided at an end of a first side in a first direction (X direction) of case body 110. First opening 113 is sealed by first sealing plate 120. A joint portion 115 is formed in first opening 113 to seal first opening 113. First opening 113 and first sealing plate 120 have a substantially rectangular shape with the Y direction as the short side direction and the Z direction as the long side direction.

[0029] A negative electrode terminal 301 (first electrode terminal) is provided on the first sealing plate 120. The position of the negative electrode terminal 301 can be changed as appropriate.

[0030] 4, a second opening 114 is provided at the end of a second side of case body 110 opposite the first side in the first direction (X direction). That is, second opening 114 is located at the end opposite to first opening 113. Second opening 114 is sealed by second sealing plate 130. A joint 115 is formed in second opening 114 to seal second opening 114. Second opening 114 and second sealing plate 130 have a substantially rectangular shape with the Y direction as the short side direction and the Z direction as the long side direction.

[0031] A positive electrode terminal 302 (second electrode terminal) and a liquid injection hole 134 are provided on the second sealing plate 130. The positions of the positive electrode terminal 302 and the liquid injection hole 134 can be changed as appropriate.

[0032] The first sealing plate 120 and the second sealing plate 130 are made of metal. Specifically, the first sealing plate 120 and the second sealing plate 130 are made of aluminum, an aluminum alloy, iron, an iron alloy, or the like.

[0033] The negative electrode terminal 301 is electrically connected to the negative electrode (first electrode) of the electrode body 200. The negative electrode terminal 301 is attached to the first sealing plate 120, that is, the case 100.

[0034] The positive electrode terminal 302 is electrically connected to the positive electrode (second electrode) of the electrode body 200. The positive electrode terminal 302 is attached to the second sealing plate 130, that is, the case 100.

[0035] The negative electrode terminal 301 is made of a conductive material (more specifically, a metal), and may be made of, for example, copper or a copper alloy. The outer surface of the negative electrode terminal 301 may be provided with a portion or layer made of aluminum or an aluminum alloy.

[0036] The positive terminal 302 is made of a conductive material (more specifically, a metal), and may be made of, for example, aluminum or an aluminum alloy.

[0037] The liquid inlet hole 134 is sealed with a sealing member (not shown), which may be, for example, a blind rivet or other metal member.

[0038] The electrode assembly 200 is a flat-shaped electrode assembly having positive and negative electrode plates, as described below. Specifically, the electrode assembly 200 is a wound-type electrode assembly in which a strip-shaped positive electrode plate and a strip-shaped negative electrode plate are wound together via a strip-shaped separator (not shown). However, in this specification, the term "electrode assembly" is not limited to a wound-type electrode assembly and may also be a stacked-type electrode assembly in which multiple positive electrode plates and multiple negative electrode plates are alternately stacked. The strip-shaped separator may be formed, for example, of a polyolefin microporous membrane. The electrode assembly may include multiple positive electrode plates and multiple negative electrode plates, and the positive electrode tabs provided on each positive electrode plate may be stacked to form a positive electrode tab group, or the negative electrode tabs provided on each negative electrode plate may be stacked to form a negative electrode tab group. The electrode assembly 200 may include multiple wound-type electrode bodies or multiple stacked-type electrode bodies.

[0039] As shown in Fig. 6, case 100 houses electrode assembly 200. Fig. 6 illustrates a first electrode assembly 201, which will be described later. First electrode assembly 201 is housed in case 100 so that its winding axis is parallel to the X direction.

[0040] Specifically, one or more wound electrode bodies are housed together with an electrolytic solution (electrolyte), not shown, inside an insulating sheet 700 (described below) placed inside the case 100. The electrolytic solution (nonaqueous electrolytic solution) can be, for example, a nonaqueous solvent made by mixing ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a volume ratio (25°C) of 30:30:40, in which LiPF is dissolved at a concentration of 1.2 mol / L. Note that a solid electrolyte may be used instead of the electrolytic solution.

[0041] The first electrode body 201 includes a main body portion (a portion where positive electrode plates and negative electrode plates are stacked with a separator interposed therebetween), a first electrode tab 220 (a negative electrode tab group), and a second electrode tab 250 (a positive electrode tab group).

[0042] The main body is composed of a negative electrode plate 210 and a positive electrode plate 240, which will be described later. The first electrode tab 220 is located at the end of a first side of the first electrode body 201 in a first direction (X direction) relative to the main body. The first side in this embodiment is the first sealing plate 120 side. The second electrode tab 250 is located at the end of a second side of the first electrode body 201 in the first direction (X direction) relative to the main body. The second side in this embodiment is the second sealing plate 130 side.

[0043] The first electrode tab 220 and the second electrode tab 250 are formed to protrude from the center portion of the electrode body 200 toward the first sealing plate 120 or the second sealing plate 130, respectively.

[0044] The current collectors 400 include a negative electrode current collector 400A and a positive electrode current collector 400B. The negative electrode current collector 400A and the positive electrode current collector 400B are each made of a plate-shaped member. The electrode assembly 200 is electrically connected to a negative electrode terminal 301 and a positive electrode terminal 302 via the current collectors 400.

[0045] The negative electrode current collector 400A is disposed on the first sealing plate 120 via a resin insulating member. The negative electrode current collector 400A is electrically connected to the first electrode tab 220 and the negative electrode terminal 301. The negative electrode current collector 400A is made of a conductive material (more specifically, a metal), and may be made of, for example, copper or a copper alloy. Details of the negative electrode current collector 400A will be described later.

[0046] The positive electrode current collector 400B is disposed on the second sealing plate 130 via a resin insulating member. The positive electrode current collector 400B is electrically connected to the second electrode tab 250 and the positive electrode terminal 302. The positive electrode current collector 400B is made of a conductive material (more specifically, a metal), such as aluminum or an aluminum alloy. The second electrode tab 250 may be electrically connected to the second sealing plate 130 directly or via the positive electrode current collector 400B. In this case, the second sealing plate 130 may serve as the positive electrode terminal 302. The positive electrode current collector 400B will be described in detail later.

[0047] (Configuration of electrode body 200) FIG. 7 is a front view showing a negative electrode blank 210S before the negative electrode plate 210 (first electrode) is formed, FIG. 8 is a cross-sectional view taken along line VIII-VIII of the negative electrode blank 210S shown in FIG. 7, and FIG. 9 is a front view showing the negative electrode plate 210 formed from the negative electrode blank 210S.

[0048] The negative electrode plate 210 is manufactured by processing a negative electrode original plate 210S. As shown in Figures 7 and 8, 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.

[0049] A negative electrode active material layer 212 is formed on both surfaces of the negative electrode substrate 211 except for one end portion. The negative electrode active material layer 212 is formed by applying a negative electrode active material layer slurry using a die coater.

[0050] 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.

[0051] The negative electrode substrate 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. The negative electrode active material layer 212 is then compressed to form a negative electrode base plate 210S including the negative electrode substrate 211 and the negative electrode active material layer 212. The negative electrode base plate 210S is cut into a predetermined shape to form the negative electrode plate 210. The negative electrode base plate 210S can be cut by laser processing using energy beam irradiation, mold processing, cutter processing, or the like.

[0052] As shown in FIG. 9, a plurality of negative electrode tabs 230 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 230 are stacked to form a first electrode tab 220. As a result, the first electrode tab 220 is connected to the negative electrode plate 210 (first electrode). The position and length in the protruding direction of each of the plurality of negative electrode tabs 230 are appropriately adjusted taking into consideration the state in which the first electrode tab 220 is connected to the negative electrode current collector 400A. The shape of the negative electrode tab 230 is not limited to that exemplified in FIG. 8.

[0053] FIG. 10 is a front view showing a positive electrode plate 240S before the positive electrode plate 240 (second electrode) is formed, FIG. 11 is a cross-sectional view of the positive electrode plate 240S shown in FIG. 10 taken along line XI-XI, and FIG. 12 is a front view showing a positive electrode plate 240 formed from the positive electrode plate 240S.

[0054] The positive electrode plate 240, which is the second electrode, has a polarity different from that of the negative electrode plate 210, which is the first electrode. The positive electrode plate 240 is manufactured by processing a positive electrode base plate 240S. As shown in FIGS. 10 and 11, the positive electrode base plate 240S includes a positive electrode core 241, a positive electrode active material layer 242, and a positive electrode protective layer 243. The positive electrode core 241 is an aluminum foil or an aluminum alloy foil.

[0055] A positive electrode active material layer 242 is formed on both surfaces of the positive electrode core 241 except for one end portion. The positive electrode active material layer 242 is formed on the positive electrode core 241 by applying a positive electrode active material layer slurry using a die coater.

[0056] 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.

[0057] The positive electrode protective layer 243 is in contact with the positive electrode core 241 and is formed on one end of the positive electrode active material layer 242 in the width direction. The positive electrode protective layer 243 is formed on the positive electrode core 241 by applying a positive electrode protective layer slurry using a die coater. The positive electrode protective layer 243 has a larger electrical resistance than the positive electrode active material layer 242.

[0058] 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.

[0059] The positive electrode substrate 241 coated with the positive electrode active material layer slurry and the positive electrode protective layer slurry is dried, and the NMP contained in the positive electrode active material layer slurry and the positive electrode protective layer slurry is removed, thereby forming the positive electrode active material layer 242 and the positive electrode protective layer 243. The positive electrode active material layer 242 is then compressed to form a positive electrode base plate 240S including the positive electrode substrate 241, the positive electrode active material layer 242, and the positive electrode protective layer 243. The positive electrode base plate 240S is cut into a predetermined shape to form the positive electrode plate 240. The positive electrode base plate 240S can be cut by laser processing using energy beam irradiation, mold processing, cutter processing, or the like.

[0060] As shown in FIG. 12, a plurality of positive electrode tabs 260 each made of a positive electrode core 241 are provided at one end in the width direction of a positive electrode plate 240 formed from a positive electrode original plate 240S. When the positive electrode plate 240 is wound, the plurality of positive electrode tabs 260 are stacked to form a second electrode tab 250. As a result, the second electrode tab 250 is connected to the positive electrode plate 240 (second electrode). The position and length in the protruding direction of each of the plurality of positive electrode tabs 260 are appropriately adjusted taking into consideration the state in which the second electrode tab 250 is connected to the positive electrode current collector 400B. The shape of the positive electrode tab 260 is not limited to that exemplified in FIG. 12.

[0061] A positive electrode protective layer 243 is provided at the base of each of the positive electrode tabs 260. The positive electrode protective layer 243 does not necessarily have to be provided at the base of the positive electrode tab 260.

[0062] In a typical example, the thickness of the negative electrode tab 230 (one piece) is smaller than the thickness of the positive electrode tab 260 (one piece). In this case, the thickness of the first electrode tab 220 is smaller than the thickness of the second electrode tab 250.

[0063] (Connection structure between electrode body 200 and current collector 400) Fig. 13 is a cross-sectional view taken along line XIII-XIII of the secondary battery shown in Fig. 1. As shown in Fig. 13, the electrode body 200 includes a first electrode body 201 and a second electrode body 202. Each of the first electrode body 201 and the second electrode body 202 includes a first electrode (negative electrode) and a second electrode (positive electrode). Note that the electrode body 200 may be composed of three or more electrode bodies.

[0064] The electrode body 200 is formed by stacking a first electrode body 201 and a second electrode body 202. The first electrode body 201 and the second electrode body 202 are aligned in the thickness direction (Y direction) of the first electrode body 201 and the second electrode body 202.

[0065] The first electrode body 201 includes a first electrode tab 220. The first electrode tab 220 is electrically connected to the first electrode at a first end 205 in the X direction. The second electrode body 202 includes a third electrode tab 270. The third electrode tab 270 is electrically connected to the first electrode at a third end 207 in the X direction.

[0066] The first electrode tab 220 has a curved portion 221 and a tip portion 222. The curved portion 221 is a portion of the first electrode tab 220 that is curved on the side where the first electrode is connected relative to the tip portion 222. The tip portion 222 is a portion of the first electrode tab 220 that is located at the end opposite the side where the first electrode is connected.

[0067] The third electrode tab 270 has a curved portion 271 and a tip portion 272. The curved portion 271 is a portion of the third electrode tab 270 that is curved on the side where the first electrode is connected, relative to the tip portion 272. The tip portion 272 is a portion of the third electrode tab 270 that is located at the end opposite the side where the first electrode is connected.

[0068] The first electrode tab 220 and the third electrode tab 270 are curved in opposite directions so that the tip ends 222, 272 approach each other. In the present embodiment, the tip ends 222, 272 are spaced apart, but this configuration is not limiting, and the tip ends 222, 272 may be in contact with each other.

[0069] The negative electrode current collector 400A electrically connects the negative electrode terminal 301 to the first electrode tab 220 and the third electrode tab 270. The negative electrode current collector 400A in this embodiment is connected to the negative electrode terminal 301 between the electrode body 200 and the first sealing plate 120.

[0070] The negative electrode current collector 400A includes a first current collector 410, a third current collector 430, and a first electrode terminal side current collector 440.

[0071] The first current collector 410 is a plate-like member. The first current collector 410 has a longitudinal direction in the Z direction and a lateral direction in the Y direction. The third current collector 430 is a plate-like member. The third current collector 430 has a longitudinal direction in the Z direction and a lateral direction in the Y direction. The first current collector 410 and the third current collector 430 are Y direction In this way, the first current collector 410 and the third current collector 430 are configured as separate parts.

[0072] The first electrode tab 220 is joined to the first current collector 410 at a joining point 411, which will be described later. The third electrode tab 270 is joined to the third current collector 430 at a joining point 431, which will be described later. The joining points 411, 431 may be formed by, for example, ultrasonic welding, resistance welding, laser welding, caulking, or the like. In this embodiment, the first electrode tab 220 and the first current collector 410, and the third electrode tab 270 and the third current collector 430 are joined by, for example, ultrasonic welding.

[0073] The first electrode terminal side current collector 440 is joined to the first current collector 410 and the third current collector 430 at joints (not shown) located at the ends in the Z direction. The first electrode terminal side current collector 440 is connected to the negative electrode terminal 301. The connection between the first electrode terminal side current collector 440 and the negative electrode terminal 301 can be formed by, for example, crimping and / or welding.

[0074] Negative electrode terminal 301 is exposed to the outside of first sealing plate 120 and is provided so as to reach first electrode terminal side current collector 440 of negative electrode current collector 400A provided on the inside surface of first sealing plate 120. Negative electrode terminal 301 is connected to first plate portion 303.

[0075] The first plate portion 303 is located outside the first sealing plate 120. The first plate portion 303 is arranged so as to fit along the first sealing plate 120. The first plate portion 303 is conductive. The first plate portion 303 is arranged to ensure a connection area with a bus bar or the like that electrically connects the secondary battery 1 to another adjacent secondary battery. The connection between the negative electrode terminal 301 and the first plate portion 303 can be formed by, for example, laser welding.

[0076] A first insulating member 510 is disposed between the first plate portion 303 and the first sealing plate 120. A second insulating member 520 is disposed between the negative electrode terminal 301 and the first sealing plate 120. A third insulating member 530 is disposed between the first electrode terminal side current collector 440 and the first sealing plate 120.

[0077] However, negative electrode terminal 301 may be electrically connected to first sealing plate 120. Also, first sealing plate 120 may serve as negative electrode terminal 301.

[0078] A spacer 600 is disposed between the first sealing plate 120 and the electrode body 200. The spacer 600 is made of an insulating resin material. The spacer 600 includes a first component 610 and a second component 620. The first component 610 and the second component 620 are engaged with each other at engaging portions (not shown) at both ends in the Z direction.

[0079] The first component 610 and the second component 620 protrude in the Y direction at the end on the electrode body 200 side in the X direction. As a result, the spacer 600 plays the role of a guide to make it easier for the bending portions 221, 271 to bend when the bending portions 221, 271 are bent.

[0080] A resin insulating sheet 700 (electrode body holder) is disposed between the electrode body 200 and the case body 110. The insulating sheet 700 may be made of, for example, resin. More specifically, the material of the insulating sheet 700 is, for example, polypropylene (PP), polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polyimide (PI), or polyolefin (PO).

[0081] Fig. 14 is a cross-sectional view taken along line XIV-XIV of the secondary battery shown in Fig. 1. The connection structure between the electrode body 200 and the current collector 400 on the second electrode (positive electrode) side of the secondary battery 1 in this embodiment differs from the structure on the first electrode (negative electrode) side in that the portions corresponding to the first current collector 410 and the third current collector 430 on the first electrode (negative electrode) side are configured as a single part.

[0082] The first electrode body 201 includes a second electrode tab 250. The second electrode tab 250 is electrically connected to the second electrode at a second end 206 in the X direction. The second electrode body 202 includes a fourth electrode tab 280. The fourth electrode tab 280 is electrically connected to the second electrode at a fourth end 208 in the X direction.

[0083] The second electrode tab 250 has a curved portion 251 and a tip portion 252. The curved portion 251 is a portion of the second electrode tab 250 that is curved on the side where the second electrode is connected relative to the tip portion 252. The tip portion 252 is a portion of the second electrode tab 250 that is located at the end opposite the side where the second electrode is connected.

[0084] The fourth electrode tab 280 has a curved portion 281 and a tip portion 282. The curved portion 281 is a portion of the fourth electrode tab 280 that is curved on the side where the second electrode is connected relative to the tip portion 282. The tip portion 282 is a portion of the fourth electrode tab 280 that is located at the end opposite the side where the second electrode is connected.

[0085] The second electrode tab 250 and the fourth electrode tab 280 are curved in opposite directions so that the tip portions 252, 282 approach each other. 282 However, the present invention is not limited to this configuration, and the tip portions 252 and 282 may be in contact with each other.

[0086] The positive electrode current collector 400B electrically connects the positive electrode terminal 302 to the second electrode tab 250 and the fourth electrode tab 280. The positive electrode current collector 400B in this embodiment is connected to the positive electrode terminal 302 between the electrode body 200 and the second sealing plate 130.

[0087] The positive electrode current collector 400B includes a second current collector 420 and a second electrode terminal side current collector 450.

[0088] The second current collector 420 is a plate-like member. The second current collector 420 has a longitudinal direction in the Z direction and a lateral direction in the Y direction. The second current collector 420 is configured as a single, integrated part.

[0089] The second electrode tab 250 and the fourth electrode tab 280 are joined to the second current collector 420, which is configured as a single component, at a joining point 421, which will be described later. The joining point 421 may be formed by, for example, ultrasonic welding, resistance welding, laser welding, crimping, or the like. In the present embodiment, the second electrode tab 250 and the fourth electrode tab 280 are joined to the second current collector 420 by, for example, ultrasonic welding.

[0090] The second electrode terminal side current collector 450 is joined to the second current collector 420 at a joint (not shown) located at an end in the Z direction. The second electrode terminal side current collector 450 is connected to the positive electrode terminal 302. The connection between the second electrode terminal side current collector 450 and the positive electrode terminal 302 can be formed by, for example, crimping and / or welding.

[0091] Positive electrode terminal 302 is exposed to the outside of second sealing plate 130 and is provided so as to reach second electrode terminal side current collector 450 of positive electrode current collector 400B provided on the inside surface of second sealing plate 130. Positive electrode terminal 302 is connected to second plate portion 304.

[0092] The second plate portion 304 is located on the outside of the second sealing plate 130. The second plate portion 304 is arranged so as to fit along the second sealing plate 130. The second plate portion 304 is conductive. The second plate portion 304 is arranged to ensure a connection area between the secondary battery 1 and an external terminal. The connection between the positive electrode terminal 302 and the second plate portion 304 can be formed by, for example, laser welding.

[0093] A first insulating member 510 is disposed between the second plate portion 304 and the second sealing plate 130. A second insulating member 520 is disposed between the positive electrode terminal 302 and the second sealing plate 130. A third insulating member 530 is disposed between the second electrode terminal side current collector 450 and the second sealing plate 130.

[0094] However, the positive electrode terminal 302 may be electrically connected to the second sealing plate 130. Also, the second sealing plate 130 may serve as the positive electrode terminal 302.

[0095] A spacer 600 is disposed between the second sealing plate 130 and the electrode body 200. The spacer 600 is made of an insulating resin material. The spacer 600 includes a first component 610 and a second component 620. The first component 610 and the second component 620 are engaged with each other at engaging portions (not shown) at both ends in the Z direction.

[0096] The first component 610 and the second component 620 protrude in the Y direction at the end on the electrode body 200 side in the X direction. As a result, the spacer 600 plays the role of a guide to make it easier for the bending portions 251, 281 to bend when the bending portions 251, 281 are bent.

[0097] Between the electrode body 200 and the case body 110, an insulating sheet 700 (electrode body holder) made of resin is arranged.

[0098] (Manufacturing process of secondary battery 1) A method for manufacturing a secondary battery according to the present embodiment will be described below. Fig. 15 is a flowchart showing a method for manufacturing a secondary battery according to embodiment 1. Fig. 16 is a perspective view showing a state before two electrode bodies included in the secondary battery according to embodiment 1 are overlapped. Fig. 17 is a cross-sectional view taken along line XVII-XVII of the electrode body and current collector shown in Fig. 16.

[0099] 15, in the method for manufacturing a secondary battery according to the present embodiment, first, a first electrode body 201 and a second electrode body 202 are fabricated (step S1). A portion of the tip of each of the first electrode tab 220, the second electrode tab 250, the third electrode tab 270, and the fourth electrode tab 280 is cut off so that the tip lengths are the same when bundled.

[0100] As shown in FIGS. 15 to 17, after the first electrode body 201 and the second electrode body 202 are fabricated, the first electrode tab 220 is joined to the first current collector 410 (step S2). The first electrode tab 220 is joined to the first current collector 410 at a joining location 411. Next, the third electrode tab 270 is joined to the third current collector 430 (step S3). The third electrode tab 270 is joined to the third current collector 430 at a joining location 431.

[0101] Next, the first electrode body 201, the second current collector 420, and the second electrode body 202 are arranged in this order in one direction (DR1 direction). The second electrode tab 250 is arranged on one side of the second current collector 420 in the one direction (DR1 direction). With the fourth electrode tab 280 arranged on the other side of the second current collector 420 in the one direction (DR1 direction), the second electrode tab 250 and the fourth electrode tab 280 are joined to the second current collector 420 (step S4). The second electrode tab 250 and the fourth electrode tab 280 are joined to the second current collector 420 at joining points 421. This results in a state in which, in one direction (DR1 direction), the first electrode body 201 is arranged on one side of the second current collector 420, the second electrode body 202 is arranged on the other side of the second current collector 420, and the second electrode tab 250 and the fourth electrode tab 280 are electrically connected to the second current collector 420. Note that at this time, the second electrode tab 250 and the fourth electrode tab 280 may be connected to the second current collector 420 in a state in which they overlap.

[0102] 16, the second electrode tab 250 and the fourth electrode tab 280 are electrically connected to the second electrode body 202 with the main body of the first electrode body 201 (the portion where the positive electrode plate and the negative electrode plate are stacked with a separator interposed therebetween) separated from the main body of the second electrode body 202. In this state, when the second current collector 420 is viewed in a plan view, the main body of the first electrode body 201 and the main body of the second electrode body 202 do not overlap. Note that when the second current collector 420 is viewed in a plan view, it is preferable that the main body of the first electrode body 201 and the main body of the second electrode body 202 are positioned so that they do not overlap with the second current collector 420.

[0103] It is preferable that, with the first electrode body 201 and the second electrode body 202 aligned in one direction (DR1 direction), at least one of the second electrode tab 250 and the fourth electrode tab 280 is joined to the second current collector 420. Note that, before aligning the first electrode body 201 and the second electrode body 202 in one direction (DR1 direction), the second electrode tab 250 or the fourth electrode tab 280 may be joined to the second current collector 420 in advance. Note that, as in the present embodiment, it is particularly preferable that the second current collector 420 is a single metal component.

[0104] In the height direction of the first electrode body 201 and the second electrode body 202, the first current collector 410, the second current collector 420, and the third current collector 430 are arranged biased to one side from the center of the first electrode body 201 and the second electrode body 202. This allows the current collectors to be configured to be short, and therefore the current collectors can be made compact.

[0105] Note that the first current collector 410, the second current collector 420, and the third current collector 430 are not limited to this configuration. The first current collector 410, the second current collector 420, and the third current collector 430 may be disposed at the center of the first electrode body 201 and the second electrode body 202 in the height direction of the first electrode body 201 and the second electrode body 202. In this case, the first electrode tab 220, the second electrode tab 250, the third electrode tab 270, and the fourth electrode tab 280 are each disposed at the center of the first electrode body 201 and the second electrode body 202 in accordance with the first current collector 410, the second current collector 420, and the third current collector 430 in the height direction of the first electrode body 201 and the second electrode body 202.

[0106] Furthermore, the order of the steps of joining the first current collector 410, the second current collector 420, and the third current collector 430 to the first electrode body 201 and the second electrode body 202 is not limited to the above, and the order may be changed. The steps of joining the first current collector 410 and the third current collector 430 to the first electrode body 201 and the second electrode body 202, respectively, are preferably performed before the step of overlapping the first electrode body 201 and the second electrode body 202, which will be described later, and are preferably performed before the step of joining the second current collector 420 to the first electrode body 201 and the second electrode body 202.

[0107] Next, after joining the second electrode tab 250 and the fourth electrode tab 280 to the second current collector 420, the second electrode tab 250 and the fourth electrode tab 280 are bent in the thickness direction of the first electrode body 201 and the second electrode body 202 (the direction perpendicular to the DR1 direction in FIGS. 16 and 17) so that the first electrode tab 220 and the third electrode tab 270 face each other, and the first electrode body 201 and the second electrode body 202 are overlapped (step S5). In other words, the first electrode body 201 and the second electrode body 202 are put together. At this point, the first current collector 410, which is a metal part, and the second current collector 420, which is also a metal part, are in a state of being separate and separated from each other.

[0108] 17, the second end 206 and the fourth end 208 are brought closer to each other than in the state in the step of joining the second electrode tab 250 and the fourth electrode tab 280 to the second current collector 420. The first end 205 and the third end 207 are also brought closer to each other than in the state in the step of joining the second electrode tab 250 and the fourth electrode tab 280 to the second current collector 420. This causes the first electrode body 201 and the second electrode body 202 to overlap each other.

[0109] "Overlapping the first electrode body and the second electrode body" means that the first electrode body and the second electrode body may be directly overlapped, or another member may be placed between the first electrode body and the second electrode body. The first electrode body and the second electrode body may or may not be fixed with tape or the like. Furthermore, the first electrode body, the second current collector, and the second electrode body do not have to be arranged linearly in one direction (DR1 direction), and the first electrode body or the second electrode body may be inclined with respect to the second current collector in one direction (DR1 direction).

[0110] First electrode tab 220 and third electrode tab 270 are bent in the direction of the arrow in Figure 17. As a result, the tip ends of first electrode tab 220 and third electrode tab 270 are arranged to face each other.

[0111] Fig. 18 is a perspective view showing the state in which the holder and spacer are attached to the electrode assembly. As shown in Fig. 15 and Fig. 18, next, the spacer 600 and the insulating sheet 700 are assembled to the electrode assembly 200 (step S6). Note that after the spacer 600 and the insulating sheet 700 are assembled to the electrode assembly 200, the first electrode tab 220 and the third electrode tab 270 may be folded.

[0112] It should be noted that the insulating sheet 700 does not necessarily have to cover the entire surface of the electrode body 200. The insulating sheet 700 preferably covers approximately 50% or more, and more preferably approximately 70% or more, of the area of ​​the outer surface of the electrode body. Of the six faces of the substantially rectangular parallelepiped (flat) electrode body 200, the insulating sheet 700 preferably covers the entire four faces other than at least the two faces on which the first electrode tab 220 and the second electrode tab 250 are formed.

[0113] Fig. 19 is a perspective view showing a state in which a first sealing plate is attached to a first current collector, and Fig. 20 is a cross-sectional view taken along line XX-XX of the electrode assembly and current collector shown in Fig. 19.

[0114] As shown in Figures 15, 19 and 20, after joining the first electrode tab 220, joining the third electrode tab 270, and overlapping the first electrode body 201 and the second electrode body 202, the first current collector 410 and the third current collector 430 are electrically connected to the negative electrode terminal 301 (step S7).

[0115] It should be noted that step S7 can also be performed before step S6. Performing step S7 before step S6 facilitates a more stable electrical connection between the negative electrode terminal 301 and the first electrode tab 220 and the third electrode tab 270. It also facilitates a configuration in which the space between the first sealing plate 120 and the main body of the electrode assembly 200 is smaller.

[0116] The first electrode tab 220 and the third electrode tab 270 are bent so that the tip portions 222, 272 face each other.

[0117] The negative electrode terminal 301 and the first electrode terminal current collector 440 are attached to the first sealing plate 120 via an insulating member. Then, the first electrode terminal current collector 440 is brought into contact with the first current collector 410 and the third current collector 430 from the X direction. The first electrode terminal current collector 440 is joined to the first current collector 410 and the third current collector 430 by laser welding between the first sealing plate 120 and the insulating sheet 700. Note that the connection of the first plate portion 303 to the negative electrode terminal 301 may be made at any time.

[0118] 21 is a perspective view showing the state in which the electrode bodies are being inserted into the case body. As shown in Fig. 15 and Fig. 21, next, the overlapping first electrode body 201 and second electrode body 202 are inserted into the case body 110 from the first opening 113, with the second current collector 420 side first (step S8).

[0119] The first sealing plate 120 is brought into contact with the case body 110. At this time, the first electrode tab 220 and the third electrode tab 270 are in a curved state. As shown in Fig. 13, the first electrode tab 220 and the third electrode tab 270 are curved along the shape of the spacer 600 so that the folded-back portions of the curved portions 221, 271 approach the case body 110 in the Y direction.

[0120] Thereafter, first sealing plate 120 is temporarily joined to case body 110. By temporary joining, first sealing plate 120 is partially joined to first opening 113 of case body 110. In this way, first sealing plate 120 is positioned relative to case body 110.

[0121] When inserting the electrode body 200 into the case body 110, the electrode body 200 may be pulled from the second current collector 420 side, or may be pushed from the first current collector 410 and third current collector 430 sides. When the electrode body 200 is pushed from the first current collector 410 and third current collector 430 sides, the first electrode tab 220 and the third electrode tab 270 can be bent at the same time.

[0122] Fig. 22 is a perspective view showing a state in which a second sealing plate is attached to the second current collector. Fig. 23 is a cross-sectional view taken along line XXIII-XXIII of the electrode assembly and current collector shown in Fig. 22. Note that case body 110 is omitted from Fig. 23.

[0123] As shown in Figures 15, 22 and 23, next, after the first electrode body 201 and the second electrode body 202 are inserted into the case body 110, the second current collector 420 is electrically connected to the positive electrode terminal 302 (step S9).

[0124] Specifically, the positive electrode terminal 302 and the second electrode terminal side current collector 450 are attached to the second sealing plate 130 via an insulating member. The second electrode terminal side current collector 450 is brought into contact with the second current collector 420 from the X direction. The second electrode terminal side current collector 450 and the second current collector 420 are joined by laser welding between the second sealing plate 130 and the insulating sheet 700. Note that the second plate portion 304 may be connected to the positive electrode terminal 302 at any time.

[0125] As shown in FIG. 23, the second electrode tab 250 and the fourth electrode tab 280 are bent so that the tip portions 252, 282 face each other.

[0126] The second sealing plate 130 is brought into contact with the case body 110. This bends the second electrode tab 250 and the fourth electrode tab 280. As shown in Fig. 14, the second electrode tab 250 and the fourth electrode tab 280 are bent along the shape of the spacer 600 so that the folded-back portions of the curved portions 251, 281 approach the case body 110 in the Y direction.

[0127] Thereafter, second sealing plate 130 is pre-welded to case body 110. By pre-welding, second sealing plate 130 is partially joined to second opening 114 of case body 110. As a result, second sealing plate 130 is positioned relative to case body 110.

[0128] Fig. 24 is a perspective view showing the configuration of the secondary battery according to embodiment 1. As shown in Figs. 15 and 24, next, a first sealing plate 120 and a second sealing plate 130 are joined to the case body 110 (step S10). The first sealing plate 120 seals the first opening 113 of the case body 110, and the second sealing plate 130 seals the second opening 114 of the case body 110. This allows the first electrode body 201 and the second electrode body 202 to be housed in the case 100.

[0129] After the above steps are completed, inspections such as a leak inspection are performed (step S11). After the leak inspection, the secondary battery 1 is dried to remove moisture from inside the case 100. Then, electrolyte is injected into the inside of the case 100 through the liquid injection hole 134. When injecting the electrolyte, the case 100 is tilted with the second sealing plate 130 facing up and the first sealing plate 120 facing down, and the electrolyte is injected into the inside of the case 100 through the liquid injection hole 134 of the second sealing plate 130. Then, degassing charging is performed. The liquid injection hole 134 may be temporarily sealed during degassing charging. The liquid injection hole is then sealed, and the secondary battery 1 is completed.

[0130] In the manufacturing method of the secondary battery 1 and the secondary battery 1 according to the first embodiment of the present technology, the first electrode body 201 is disposed on one side of the second current collector 420, and the second electrode body 202 is disposed on the other side of the second current collector 420. The second electrode tab 250 and the fourth electrode tab 280 are electrically connected to the second current collector 420, and then the first electrode body 201 and the second electrode body 202 are overlapped. This configuration allows the first electrode body 201 and the second electrode body 202 to form a single electrode tab, which can be shortened compared to when this electrode tab is folded. Furthermore, this configuration allows the length of each tab to be shortened compared to when the second electrode tab 250 and the fourth electrode tab 280 of the overlapped first electrode body 201 and second electrode body 202 are connected to the second current collector 420, respectively. As a result, the volume occupied by the electrode tabs can be reduced, thereby improving the energy density of the secondary battery 1. Furthermore, forming separate electrode tabs for the first electrode body 201 and the second electrode body 202 and bending each of these electrode tabs to form the first electrode body 201 and the second electrode body 202 makes it easier to bend the electrode tabs compared to forming a single electrode tab from the first electrode body 201 and the second electrode body 202, making it easier to join the electrode tabs to the current collectors and allowing for stable production of the secondary battery. In particular, stable production of the secondary battery 1 can increase the reliability of the connections between the electrode tabs and the current collectors.

[0131] In the manufacturing method of the secondary battery 1 according to embodiment 1 of the present technology, after the second electrode tab 250 and the fourth electrode tab 280 are joined by the second current collector 420, the first electrode body 201 and the second electrode body 202 are inserted into the case body 110 from the side of the second current collector 420 that has been joined together, thereby making it easier to insert the electrode body 200 into the case body 110.

[0132] In the manufacturing method of the secondary battery 1 and the secondary battery 1 according to the first embodiment of the present technology, separate electrode tabs are formed in the first electrode body 201 and the second electrode body 202, and the electrode body 200, in which the first electrode body 201 and the second electrode body 202 are formed by bending each of these electrode tabs, can be applied to a case body 110 having a first opening 113 and a second opening 114 located at an end opposite to the first opening 113. This allows the secondary battery 1 to be made low-profile when the first opening 113 and the second opening 114 of the case body 110 are arranged side by side in the horizontal direction.

[0133] In the manufacturing method of the secondary battery 1 and the secondary battery 1 according to the first embodiment of the present technology, the first electrode tab 220 and the third electrode tab 270 are each curved in opposite directions so that the tip portions 222, 272 located at the end opposite to the side to which the first electrode is connected approach each other, thereby making it possible to form the electrode tab easily from the outside in the thickness direction of the electrode body.

[0134] In the manufacturing method of the secondary battery 1 and the secondary battery 1 according to the first embodiment of the present technology, compared to connecting separate current collectors to the electrode tabs of the first electrode body 201 and the second electrode body 202, the electrode tabs can be connected by the second current collector 420 which is formed from a single integrated part, thereby reducing the number of connection points of the constituent parts and increasing the reliability of the connection between the electrode tabs and the current collectors.

[0135] Hereinafter, secondary batteries according to embodiment 2 and embodiment 3 will be described. The secondary batteries according to these embodiments have a different connection structure between the electrode body and the current collector from secondary battery 1 according to embodiment 1 of the present technology, and therefore, description of the same configuration as secondary battery 1 according to embodiment 1 of the present technology will not be repeated.

[0136] (Embodiment 2) Fig. 25 is a cross-sectional view showing the configuration of a secondary battery according to embodiment 2. Fig. 26 is a plan view showing a state before two electrode bodies included in the secondary battery according to embodiment 2 are overlapped.

[0137] As shown in FIG. 25, in the secondary battery according to the second embodiment, the first electrode tab 220A and the third electrode tab 270A each have leading ends 222A, 272A bent in the same direction in the Y direction.

[0138] Thereafter, the first electrode body 201A and the second electrode body 202A are inserted into the case body, and the first sealing plate 120 is brought into contact with the case body. As a result, the first electrode tab 220A and the third electrode tab 270A are curved in the same direction so that the tip portions 222A and 272A located at the ends opposite to the side where the first electrode is connected face in the same direction. To facilitate bending the tip portions 222A and 272A in the same direction, the third component 630A of the spacer 600A is provided between the first electrode tab 220A and the third electrode tab 270A.

[0139] When the tip portions 222A, 272A of the first electrode tab 220A and the third electrode tab 270A are curved in the same direction in the Y direction, the first electrode body 201A and the second electrode body 202A can be configured as one type of electrode body 200A.

[0140] 26, before the first electrode body 201A and the second electrode body 202A are stacked and in a state in which the first electrode body 201A and the second electrode body 202A are joined to the second current collector 420A, the first current collector 410A is joined to the first electrode tab 220A in a state in which it is arranged on one side (the far side of the paper in FIG. 26) in the thickness direction of the electrode body 200A that is orthogonal to one direction (DR1 direction) relative to the first electrode tab 220A. Also, the third current collector 430A is joined to the third electrode tab 270A in a state in which it is arranged on the other side (the near side of the paper in FIG. 26) in the thickness direction of the electrode body 200A that is orthogonal to the one direction (DR1 direction) relative to the third electrode tab 270A.

[0141] Before the first electrode body 201A and the second electrode body 202A are joined to the second current collector 420A, the positional relationship of the first current collector 410A to the first electrode tab 220A and the positional relationship of the third current collector 430A to the third electrode tab 270A are the same. For example, when the second electrode body 202A is viewed so that the third electrode tab 270A is located on the left side of the center of the second electrode body 202A in the plan view of Figure 26, the positional relationship of the first current collector 410A to the first electrode tab 220A and the positional relationship of the third current collector 430A to the third electrode tab 270A are the same, in that the current collectors are located on the far side of the paper surface in Figure 26 relative to the electrode tabs. Therefore, before the first electrode body 201A and the second electrode body 202A are joined to the second current collector 420A, the first electrode body 201A and the second electrode body 202A can be configured as one type of electrode body 200A.

[0142] After the first electrode body 201A and the second electrode body 202A are stacked, as shown in FIG. 25, the first current collector 410 and the third current collector 430 are bent so as to be positioned closer to the first sealing plate 120 than the first electrode tab 220A and the third electrode tab 270A, and the tip portions 222A, 272A are bent in the same direction in the Y direction.

[0143] In the manufacturing method of a secondary battery and the secondary battery according to the second embodiment of the present technology, the first electrode tab 220A and the third electrode tab 270A are curved in the same direction so that the tip portions 222A, 272A of the first electrode tab 220A and the third electrode tab 270A face in the same direction, thereby making it possible to make the positional relationship of the first current collector 410A relative to the first electrode tab 220A and the positional relationship of the third current collector 430A relative to the third electrode tab 270A the same. This allows the first electrode body 201A and the second electrode body 202 to be configured as one type of electrode body 200A, making it easier to manufacture the electrode body 200A.

[0144] (Embodiment 3) FIG. 27 is a plan view showing the state before two electrode bodies included in the secondary battery according to embodiment 3 are overlapped.

[0145] 27, second current collector 420B included in the secondary battery according to embodiment 3 may be composed of three members. Specifically, second current collector 420B has first portion 425B, second portion 426B, and third portion 427B.

[0146] The first portion 425B is joined to the second electrode tab 250B, and the second portion 426B is joined to the fourth electrode tab 280B. Thereafter, with the first electrode body 201B and the second electrode body 202B aligned in one direction (DR1 direction), the third portion 427B connects the first portion 425B and the second portion 426B to form an integrated second current collector 420B. The third portion 427B is joined to the first portion 425B and the second portion 426B. The second current collector 420B is finally configured as a single integrated component.

[0147] Here, first portion 425B and second portion 426B are each made of metal. Third portion 427B is made of a resin material, and first portion 425B and second portion 426B can be held by third portion 427B. This results in integrated second current collector 420B. Note that the above-mentioned holding method may include fitting, bonding, welding, etc. Note that third portion 427B is not limited to being made of a resin material.

[0148] In the manufacturing method of a secondary battery and the secondary battery according to the third embodiment of the present technology, the first electrode body 201B is disposed on one side of the second current collector 420B, and the second electrode body 202B is disposed on the other side of the second current collector 420B. The second electrode tab 250B and the fourth electrode tab 280B are then electrically connected to the second current collector 420B, and the first electrode body 201B and the second electrode body 202B are then overlapped. This configuration allows the first electrode body 201B and the second electrode body 202B to form a single electrode tab, which can be shortened compared to when this electrode tab is folded. This configuration also allows the length of each tab to be shortened compared to when the second electrode tab 250B and the fourth electrode tab 280B of the overlapped first electrode body 201B and the second electrode body 202B are connected to the second current collector 420B, respectively. As a result, the volume occupied by the electrode tabs can be reduced, thereby improving the energy density of the secondary battery. Furthermore, forming separate electrode tabs for the first electrode body 201B and the second electrode body 202B and bending each of these electrode tabs to form the first electrode body 201B and the second electrode body 202B makes it easier to bend the electrode tabs than forming a single electrode tab from the first electrode body 201B and the second electrode body 202B, making it easier to join the electrode tabs to the current collectors and allowing for stable production of secondary batteries. In particular, stable production of secondary batteries can increase the reliability of the connections between the electrode tabs and the current collectors.

[0149] Although the embodiments of the present technology have been described above, the embodiments disclosed herein should be considered to be 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 meaning and scope of the claims. [Explanation of symbols]

[0150] 1 secondary battery, 100 case, 110 case body, 111 first side portion, 112, 112A, 112B second side portion, 113 first opening, 114 second opening, 115 joint portion, 120 first sealing plate, 130 second sealing plate, 134 liquid inlet, 150 gas release valve, 200, 200A electrode body, 201, 201A, 201B first electrode body, 202, 202A, 202B second electrode body, 205 first end, 206 second end, 207 third end, 208 fourth end, 210 negative electrode plate, 210S negative electrode base plate, 211 negative electrode core, 212 negative electrode active material layer, 220, 220A first electrode tab, 221, 251, 271, 281 Curved portion, 222, 222A, 252, 272, 272A, 282 Tip portion, 230 Negative electrode tab, 240 Positive electrode plate, 240S Positive electrode base plate, 241 Positive electrode core, 242 Positive electrode active material layer, 243 Positive electrode protective layer, 250, 250B Second electrode tab, 260 Positive electrode tab, 270, 270A Third electrode tab, 280, 280B Fourth electrode tab, 300 Electrode terminal, 301 Negative electrode terminal, 302 Positive electrode terminal, 303 First plate portion, 304 Second plate portion, 400 Current collector, 400A Negative electrode current collector, 400B Positive electrode current collector, 410, 410A First current collector, 411, 421, 431 Joint portion, 420, 420A, 420B Second current collector, 425B first part, 426B second part, 427B third part, 430, 430A third current collector, 440 first electrode terminal side current collector, 450 second electrode terminal side current collector, 510 first insulating member, 520 second insulating member, 530 third insulating member, 600, 600A spacer, 610 first part, 620 second part, 630A third part, 700 insulating sheet.

Claims

1. a first electrode body and a second electrode body, each of which includes a first electrode and a second electrode having a polarity different from that of the first electrode; a case that houses the first electrode body and the second electrode body; a first electrode terminal electrically connected to the first electrode, the first electrode body includes a first electrode tab disposed at a first end and electrically connected to the first electrode, and a second electrode tab disposed at a second end and electrically connected to the second electrode; the second electrode body includes a third electrode tab disposed at a third end and electrically connected to the first electrode, and a fourth electrode tab disposed at a fourth end and electrically connected to the second electrode; the first electrode tab is joined to a first current collector; the second electrode tab and the fourth electrode tab are joined to a second current collector; the third electrode tab is joined to a third current collector; A method for manufacturing a secondary battery, wherein the first current collector and the third current collector are configured as separate components, fabricating the first electrode body and the second electrode body; a step of joining the first electrode tab to the first current collector after fabricating the first electrode body and the second electrode body; a step of joining the third electrode tab to the third current collector after fabricating the first electrode body and the second electrode body; a step of electrically connecting the second electrode tab and the fourth electrode tab to the second current collector in a state in which the first electrode body is disposed on one side of the second current collector and the second electrode body is disposed on the other side of the second current collector after the first electrode body and the second electrode body are fabricated; a step of bending the second electrode tab and the fourth electrode tab after joining the second electrode tab and the fourth electrode tab to the second current collector, and overlapping the first electrode body and the second electrode body; and after overlapping the first electrode body and the second electrode body, electrically connecting the first current collector joined to the first electrode tab and the third current collector joined to the third electrode tab to the first electrode terminal.

2. the case includes a case body having a first opening and a first sealing plate that seals the first opening, the first sealing plate is provided with the first electrode terminal, 2. The method for manufacturing a secondary battery according to claim 1, further comprising a step of inserting the first electrode body and the second electrode body into the case body from the first opening, with the second current collector side leading, after the first electrode body and the second electrode body are stacked on top of each other.

3. the case body has a second opening at an end opposite to the first opening, the case includes a second sealing plate that seals the second opening, a second electrode terminal electrically connected to the second electrode is provided on the second sealing plate; 3. The method for manufacturing a secondary battery according to claim 2, further comprising the step of electrically connecting the second current collector to the second electrode terminal after inserting the first electrode body and the second electrode body into the case body.

4. 4. The method for manufacturing a secondary battery according to claim 1, wherein the first electrode tab and the third electrode tab are curved in opposite directions so that tip portions located at ends opposite to the side to which the first electrode is connected approach each other.

5. 4. The method for manufacturing a secondary battery according to claim 1, wherein each of the first electrode tab and the third electrode tab is curved in the same direction so that tip portions located at the end opposite to the side to which the first electrode is connected face in the same direction.

6. The method for manufacturing a secondary battery according to claim 1 or 2, wherein the second current collector is formed of a single component.

7. a first electrode body and a second electrode body, each of which includes a first electrode and a second electrode having a polarity different from that of the first electrode; a case that houses the first electrode body and the second electrode body; a first electrode terminal electrically connected to the first electrode, the first electrode body includes a first electrode tab disposed at a first end and electrically connected to the first electrode, and a second electrode tab disposed at a second end and electrically connected to the second electrode; the second electrode body includes a third electrode tab disposed at a third end and electrically connected to the first electrode, and a fourth electrode tab disposed at a fourth end and electrically connected to the second electrode; the first electrode body and the second electrode body are aligned in a thickness direction of the first electrode body and the second electrode body, the first electrode tab is joined to a first current collector; the second electrode tab and the fourth electrode tab are joined to a second current collector; the third electrode tab is joined to a third current collector; the first current collector and the third current collector are formed as separate parts, A secondary battery, wherein the second current collector is constituted by a single component.

8. the case includes a case body having a first opening and a first sealing plate that seals the first opening, The secondary battery according to claim 7 , wherein the first sealing plate is provided with the first electrode terminal.

9. the case body has a second opening at an end opposite to the first opening, the case includes a second sealing plate that seals the second opening, The secondary battery according to claim 8 , wherein the second sealing plate is provided with a second electrode terminal electrically connected to the second electrode.

10. 10. The secondary battery according to claim 7, wherein the second electrode tab and the fourth electrode tab are curved in opposite directions so that tip portions located at ends opposite to the side to which the second electrode is connected approach each other.

11. 9. The secondary battery according to claim 7, wherein the first electrode tab and the third electrode tab are curved in opposite directions so that tip portions located at ends opposite to the side to which the first electrode is connected approach each other.

12. 9. The secondary battery according to claim 7, wherein each of the first electrode tab and the third electrode tab is curved in the same direction so that tip portions located at the end opposite to the side to which the first electrode is connected face in the same direction.

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