Secondary battery and manufacturing method thereof

Abstract

To provide a secondary battery and a method for manufacturing the same that allow secondary batteries that have high energy density and are highly reliable to be stably and efficiently manufactured.SOLUTION: In a secondary battery, a first electrode tab group includes a plurality of first electrode tabs having mutually different first lengths from the base of the first electrode tab group to a first joint, and a second electrode tab group includes a plurality of second electrode tabs having mutually different second lengths from the base of the second electrode tab group to a second joint, and a maximum first length L1 in the first electrode tab group and a maximum second length L2 in the second electrode tab group satisfy the relationship L2 / L1>1.2.SELECTED DRAWING: Figure 28

Description

[Technical Field]

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

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

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

[0004] From the viewpoint of stably and efficiently producing a highly reliable secondary battery and from the viewpoint of improving the energy density, there is room for further improvement in the battery described in Patent Document 1.

[0005] An object of the present technology is to provide a secondary battery that can stably and efficiently produce a highly reliable secondary battery with high energy density, and a method for producing the same. [Means for solving the problem]

[0006] The present technology provides the following secondary battery and method for manufacturing the same.

[0007] [1] An electrode assembly includes a first electrode and a second electrode having a polarity different from that of the first electrode, a first electrode tab group electrically connected to the first electrode at a first end, and a second electrode tab group electrically connected to the second electrode at a second end opposite to the first end, a case for accommodating the electrode assembly, and a first electrode terminal and a second electrode terminal provided on the case, the case including a case body having a first opening and a second opening facing the first opening, a first sealing plate provided with the first electrode terminal and sealing the first opening, and a second sealing plate provided with the second electrode terminal and sealing the second opening, the first electrode terminal and the first electrode tab group being electrically connected, are electrically connected, the first electrode tab group has a first joint portion joined to a first other component so as to form a conductive path to the first electrode terminal, the second electrode tab group has a second joint portion joined to a second other component so as to form a conductive path to the second electrode terminal, the first electrode tab group includes a plurality of first electrode tabs having first lengths from a base of the first electrode tab group to the first joint portion that are different from one another, and the second electrode tab group includes a plurality of second electrode tabs having second lengths from a base of the second electrode tab group to the second joint portion that are different from one another, and a maximum first length L1 in the first electrode tab group and a maximum second length L2 in the second electrode tab group satisfy the relationship L2 / L1>1.2.

[0008] [2] The secondary battery according to [1], wherein the first other component is contained in a first current collector housed in the case and electrically connects the first electrode and the first electrode terminal, the second other component is contained in a second current collector housed in the case and electrically connects the second electrode and the second electrode terminal, the first electrode tab group has a first curved portion, and the tip side of the first curved portion in the first electrode tab group is joined to the first current collector to form a first joint, and the second electrode tab group has a second curved portion, and the tip side of the second curved portion in the second electrode tab group is joined to the second current collector to form a second joint.

[0009] [3] The secondary battery according to [2], wherein the region of the first current collector where the first joint is located is disposed along the first sealing plate, and the region of the second current collector where the second joint is located is disposed along the second sealing plate.

[0010] [4] The secondary battery according to any one of [1] to [3], wherein an electrolyte solution is contained in the case, a through-hole is formed in the second sealing plate and sealed with a sealing member, the first electrode has a first active material layer, and the second electrode has a second active material layer, wherein a first distance D1 from an end of the first active material layer facing the first sealing plate to the first sealing plate in a direction connecting the first sealing plate and the second sealing plate and a second distance D2 from an end of the second active material layer facing the second sealing plate to the second sealing plate satisfy the relationship D2 > D1.

[0011] [5] The secondary battery according to any one of [1] to [3], further comprising a first spacer disposed between the first sealing plate and the electrode body, and a second spacer disposed between the second sealing plate and the electrode body.

[0012] [6] The secondary battery according to any one of [1] to [3], wherein the first minimum length L1' in the first electrode tab group and the second minimum length L2' in the second electrode tab group satisfy the relationship L2' / L1'>1.5.

[0013] [7] The secondary battery according to any one of [1] to [3], wherein the thickness of the plurality of second electrode tabs is greater than the thickness of the plurality of first electrode tabs.

[0014] [8] A process of preparing a case body having a first opening and a second opening opposite the first opening; a process of producing an electrode body including a first electrode and a second electrode having a polarity different from that of the first electrode, having a first electrode tab group electrically connected to the first electrode at a first end and a second electrode tab group electrically connected to the second electrode at a second end opposite to the first end; a process of inserting the electrode body into the case body from the second end side through the first opening after producing the electrode body; a process of electrically connecting a first electrode terminal provided on a first sealing plate to the first electrode tab group; a process of electrically connecting a second electrode terminal provided on a second sealing plate to the second electrode tab group after electrically connecting the first electrode terminal to the first electrode tab group; and sealing the second opening with a second sealing plate after electrically connecting the second electrode terminal and the second electrode tab group, wherein the first electrode tab group has a first joint portion joined to a first other component so as to form a conductive path to the first electrode terminal, the second electrode tab group has a second joint portion joined to a second other component so as to form a conductive path to the second electrode terminal, the first electrode tab group includes a plurality of first electrode tabs having first lengths from a base of the first electrode tab group to the first joint portion that are different from one another, and the second electrode tab group includes a plurality of second electrode tabs having second lengths from a base of the second electrode tab group to the second joint portion that are different from one another, and a maximum first length L1 in the first electrode tab group and a maximum second length L2 in the second electrode tab group satisfy the relationship L2 / L1>1.2.

[0015] [9] The method for manufacturing a secondary battery according to [8], wherein the first electrode terminal and the first electrode tab group are electrically connected before the electrode body is inserted into the case body.

[0016]

[10] A method for manufacturing a secondary battery according to [8] or [9], wherein the first other component is contained in a first current collector housed in the case body and electrically connects the first electrode and the first electrode terminal, and the second other component is contained in a second current collector housed in the case body and electrically connects the second electrode and the second electrode terminal.

[0017]

[11] A method for manufacturing a secondary battery described in [8] or [9], in which the first other component and the first electrode tab group are joined and the second other component and the second electrode tab group are joined before inserting the electrode body into the case body.

[0018]

[12] The method for manufacturing a secondary battery according to [8] or [9], further comprising the step of covering the electrode assembly with an insulating electrode assembly holder before it is inserted into the case body.

[0019]

[13] A method for manufacturing a secondary battery according to [8] or [9], further comprising the steps of injecting an electrolyte into the case body through an injection hole formed in the second sealing plate and sealing the injection hole with a sealing member, wherein the electrolyte is injected into the case body while the case body is tilted so that the direction connecting the first sealing plate and the second sealing plate intersects with the horizontal direction and the second sealing plate is positioned vertically above the first sealing plate.

[0020]

[14] The method for manufacturing a secondary battery according to

[13] , wherein an electrolyte solution is poured into the case body with a spacer disposed between the first sealing plate and the electrode body. [Effects of the Invention]

[0021] According to the secondary battery and its manufacturing method of the present technology, the maximum value L1 of the first length from the base of the first electrode tab group to the first joint and the maximum value L2 of the second length from the base of the second electrode tab group to the second joint satisfy a predetermined relationship (L2 / L1>1.2), and as a result, the first electrode tabs are formed relatively short and the second electrode tabs are formed relatively long.

[0022] By forming the first electrode tab relatively short, the volume occupied by the electrode body in the space inside the case body can be increased, thereby improving the energy density of the secondary battery.

[0023] By forming the second electrode tabs relatively long, when the electrode body is inserted into the case body from the second end side, the second electrode tab group and the second other component can be easily joined at the second opening side, which makes it possible to stably and efficiently manufacture secondary batteries.

[0024] As described above, according to the present technology, it is possible to provide a secondary battery and a method for manufacturing the same that enable stable and efficient manufacturing of a highly reliable secondary battery with high energy density. [Brief explanation of the drawings]

[0025] [Figure 1] FIG. 2 is a front view of the secondary battery. [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] FIG. 2 is a front cross-sectional view of the secondary battery shown in FIG. [Figure 6] FIG. 2 is a front view showing a negative electrode blank before being formed into a negative electrode plate. [Figure 7] 7 is a cross-sectional view taken along the line VII-VII of the negative electrode plate shown in FIG. 6. FIG. [Figure 8] FIG. 2 is a front view showing a negative electrode plate formed from a negative electrode original plate. [Figure 9] FIG. 2 is a front view showing a positive electrode plate before it is formed into a positive electrode plate. [Figure 10] 10 is a cross-sectional view taken along the line XX in FIG. 9. [Figure 11] FIG. 2 is a front view showing a positive electrode plate formed from a positive electrode original plate. [Figure 12] FIG. 2 is a diagram showing an electrode assembly and a current collector taken out from a secondary battery. [Figure 13] FIG. 2 is a diagram showing a connection structure between a negative electrode tab group and a negative electrode current collector. [Figure 14] FIG. 14 is a front view of the connection structure shown in FIG. [Figure 15] FIG. 14 is a cross-sectional view of the connection structure shown in FIG. [Figure 16] 10A and 10B are diagrams showing a process of inserting the electrode body into the case body. [Figure 17] 10A and 10B are diagrams showing a step of arranging a spacer between the sealing plate and the electrode body. [Figure 18] FIG. 10 is a cross-sectional view showing a state in which a spacer is disposed between the sealing plate and the electrode body. [Figure 19] FIG. 2 is a diagram showing a connection structure between a positive electrode tab group and a positive electrode current collector. [Figure 20] FIG. 20 is a cross-sectional view of the connection structure shown in FIG. [Figure 21] 10A and 10B are cross-sectional views showing modified examples of a spacer disposed between the sealing plate and the electrode body. [Figure 22] FIG. 22 is a diagram showing the spacer on the negative electrode side shown in FIG. 21. [Figure 23] 22 is a diagram showing the spacer on the positive electrode side shown in FIG. 21. FIG. [Figure 24] 10A and 10B are diagrams illustrating differences in the lengths of a plurality of negative electrode tabs included in a negative electrode tab group. [Figure 25] FIG. 10 is a diagram for explaining the length of a negative electrode tab from the base of the negative electrode tab group to a joint portion. [Figure 26] 10A and 10B are diagrams illustrating differences in the lengths of a plurality of positive electrode tabs included in a positive electrode tab group. [Figure 27] FIG. 10 is a diagram for explaining the length of the positive electrode tab from the base of the positive electrode tab group to the joint portion. [Figure 28] FIG. 10 is a diagram for explaining the distance from the end of the electrode active material layer on the sealing plate side to the sealing plate. [Figure 29] FIG. 2 is a flow chart showing each step of a method for manufacturing a secondary battery. DETAILED DESCRIPTION OF THE INVENTION

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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).

[0030] In this specification, the term "battery" is not limited to lithium-ion batteries, but may include other batteries such as nickel-metal hydride batteries and sodium-ion batteries. In this specification, the term "electrode" may collectively refer to positive and negative electrodes. Furthermore, the term "electrode plate" may collectively refer to positive and negative plates.

[0031] (Overall battery configuration) Fig. 1 is a front view of a secondary battery 1 according to the present embodiment. Figs. 2 to 4 are views of the secondary battery 1 shown in Fig. 1 as viewed from the directions of arrows II, III, and IV, respectively. Fig. 5 is a front cross-sectional view of the secondary battery 1 shown in Fig. 1.

[0032] 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.

[0033] 1 to 5, the secondary battery 1 includes an exterior body 100, an electrode assembly 200, and a current collector 300. The exterior body 100 includes a case main body 110, a sealing plate 121 (first sealing plate), and a sealing plate 122 (second sealing plate).

[0034] In this specification, the X-axis direction (first direction) shown in Figures 1 to 5 may be referred to as the "width direction" of the secondary battery 1 or the case body 110, the Y-axis direction (second direction) may be referred to as the "thickness direction" of the secondary battery 1 or the case body 110, and the Z-axis direction (third direction) may be referred to as the "height direction" of the secondary battery 1 or the case body 110.

[0035] When configuring a battery pack including the secondary batteries 1, multiple secondary batteries 1 are stacked in their thickness direction. The stacked secondary batteries 1 may be constrained in the stacking direction (Y-axis direction) by a constraining member to form a battery module, or the battery pack may be directly supported on the side surface of the battery pack case without using a constraining member.

[0036] 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.

[0037] As shown in Figures 1 and 2, sealing plates 121, 122 are provided at both ends of the case body. The case body 110 can be formed into a rectangular tube shape, for example, by abutting the edges of bent plate-like members (joint 110A shown in Figure 2) and joining them together (for example, by laser welding). The corners of the "rectangular tube" may be rounded.

[0038] In this embodiment, the case body 110 is formed so that it is longer in the width direction (X-axis direction) of the secondary battery 1 than in the thickness direction (Y-axis direction) and height direction (Z-axis direction) of the secondary battery 1. The dimension (width) of the case body 110 in the X-axis direction is preferably about 30 cm or more. This allows for the construction of a relatively large (high-capacity) secondary battery 1. The dimension (height) of the case body 110 in the Z-axis direction is preferably about 20 cm or less, more preferably about 15 cm or less, and even more preferably about 10 cm or less. This allows for the construction of a relatively low-height secondary battery 1, which improves, for example, the mountability in a vehicle.

[0039] 3, an opening 111 (first opening) is provided at one end of the case body 110. The opening 111 is sealed by a sealing plate 121. The sealing plate 121 is provided with a negative electrode terminal 131 (first electrode terminal), a liquid inlet hole 141, and a gas release valve 151. The positions of the negative electrode terminal 131, the liquid inlet hole 141, and the gas release valve 151 can be changed as appropriate. The opening 111 and the sealing plate 121 have a substantially rectangular shape with the Y-axis direction as the short side direction and the Z-axis direction as the long side direction.

[0040] 4, an opening 112 (second opening) is provided at one end of the case body 110. The opening 112 is sealed by a sealing plate 122. The sealing plate 122 is provided with a positive electrode terminal 132 (second electrode terminal), a liquid inlet hole 142, and a gas release valve 152. The positions of the positive electrode terminal 132, the liquid inlet hole 142, and the gas release valve 152 can be changed as appropriate. The opening 112 and the sealing plate 122 have a substantially rectangular shape with the Y-axis direction as the short side direction and the Z-axis direction as the long side direction.

[0041] The sealing plates 121 and 122 are made of metal. Specifically, the sealing plates 121 and 122 are made of aluminum, an aluminum alloy, iron, an iron alloy, or the like.

[0042] The negative electrode terminal 131 is electrically connected to the negative electrode of the electrode assembly 200. The positive electrode terminal 132 is electrically connected to the positive electrode of the electrode assembly 200.

[0043] The negative electrode terminal 131 is made of a conductive material (more specifically, a metal), and may be made of, for example, copper or a copper alloy. The outer surface of the negative electrode terminal 131 may be provided with a portion or layer made of aluminum or an aluminum alloy.

[0044] The positive electrode terminal 132 is made of a conductive material (more specifically, a metal), and may be made of, for example, aluminum or an aluminum alloy.

[0045] The liquid inlet holes 141 and 142 are sealed with a sealing member (not shown), which may be, for example, a blind rivet or other metal member.

[0046] Gas exhaust valves 151 and 152 break when the pressure inside exterior body 100 reaches or exceeds a predetermined value, and exhaust gas inside exterior body 100 to the outside.

[0047] The electrode assembly 200 is a flat-shaped electrode assembly having positive and negative electrode plates, which will be described later. 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 with a strip-shaped separator (not shown) interposed therebetween. However, in this specification, the "electrode assembly" is not limited to a wound-type electrode assembly, but may also be a stacked-type electrode assembly in which multiple positive electrode plates and multiple negative electrode plates are alternately stacked. 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.

[0048] 5, the exterior body 100 houses the electrode assembly 200. The electrode assembly 200 is housed in the exterior body 100 so that its winding axis is parallel to the X-axis direction.

[0049] Specifically, one or more wound electrode bodies are housed together with an electrolytic solution (electrolyte), not shown, inside an insulating sheet 600 (described below) disposed within the exterior housing 100. The electrolytic solution (non-aqueous electrolytic solution) may be, for example, a non-aqueous solvent obtained by mixing ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a volume ratio (25°C) of 30:30:40, in which LiPF6 is dissolved at a concentration of 1.2 mol / L. Note that a solid electrolyte may be used instead of the electrolytic solution.

[0050] The electrode assembly 200 includes a negative electrode tab group 210A (first electrode tab group) provided at an end (first end) on the sealing plate 121 side, and a positive electrode tab group 220A (second electrode tab group) provided at an end (second end) on the sealing plate 122 side. The negative electrode tab group 210A and the positive electrode tab group 220A are connected to the negative electrode and positive electrode, respectively, of the electrode assembly 200. The negative electrode tab group 210A and the positive electrode tab group 220A are formed so as to protrude from a main body portion of the electrode assembly 200 (a portion where positive electrode plates and negative electrode plates are stacked with a separator interposed between them) toward the sealing plates 121, 122, respectively.

[0051] The current collector 300 includes a negative electrode current collector 310 (first current collector) and a positive electrode current collector 320 (second current collector). The negative electrode current collector 310 and the positive electrode current collector 320 are each made of a plate-shaped member. The electrode assembly 200 is electrically connected to the negative electrode terminal 131 and the positive electrode terminal 132 via the current collector 300.

[0052] The negative electrode current collector 310 is disposed on the sealing plate 121 via a resin insulating member 410. The negative electrode current collector 310 is electrically connected to the negative electrode tab group 210A and the negative electrode terminal 131. The negative electrode current collector 310 is made of a conductive material (more specifically, a metal), and may be made of, for example, copper or a copper alloy.

[0053] The positive electrode current collector 320 is disposed on the sealing plate 122 via a resin insulating member 420. The positive electrode current collector 320 is electrically connected to the positive electrode tab group 220A and the positive electrode terminal 132. The positive electrode current collector 320 is made of a conductive material (more specifically, a metal), and may be made of, for example, aluminum or an aluminum alloy. The positive electrode tab group 220A may be electrically connected to the sealing plate 122 directly or via the positive electrode current collector 320. In this case, the sealing plate 122 may also serve as the positive electrode terminal 132.

[0054] (Configuration of electrode body 200) FIG. 6 is a front view showing a negative electrode plate 210S before the negative electrode plate 210 (first electrode) is formed, FIG. 7 is a cross-sectional view taken along line VII-VII of the negative electrode plate 210S shown in FIG. 6, and FIG. 8 is a front view showing the negative electrode plate 210 formed from the negative electrode plate 210S.

[0055] The negative electrode plate 210 is manufactured by processing a negative electrode original plate 210S. As shown in Figures 6 and 7, the negative electrode original plate 210S includes a negative electrode core 211 and a negative electrode active material layer 212. The negative electrode core 211 is a copper foil or a copper alloy foil.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] As shown in FIG. 8, a plurality of negative electrode tabs 210B each made of a negative electrode core 211 is provided at one end in the width direction of a negative electrode plate 210 formed from a negative electrode original plate 210S. When the negative electrode plate 210 is wound, the plurality of negative electrode tabs 210B are stacked to form a negative electrode tab group 210A. The position and length in the protruding direction of each of the plurality of negative electrode tabs 210B are adjusted as appropriate, taking into account the state in which the negative electrode tab group 210A is connected to the negative electrode current collector 310. The shape of the negative electrode tabs 210B is not limited to the example shown in FIG. 8.

[0060] FIG. 9 is a front view showing a positive electrode plate 220S before the positive electrode plate 220 (second electrode) is formed, FIG. 10 is a cross-sectional view of the positive electrode plate 220S shown in FIG. 9 taken along line XX, and FIG. 11 is a front view showing a positive electrode plate 220 formed from the positive electrode plate 220S.

[0061] The positive electrode plate 220 is manufactured by processing a positive electrode original plate 220S. As shown in Figures 9 and 10, the positive electrode original plate 220S includes a positive electrode core 221, a positive electrode active material layer 222, and a positive electrode protective layer 223. The positive electrode core 221 is an aluminum foil or an aluminum alloy foil.

[0062] A positive electrode active material layer 222 is formed on both surfaces of the positive electrode core 221 except for one end portion. The positive electrode active material layer 222 is formed on the positive electrode core 221 by applying a positive electrode active material layer slurry using a die coater.

[0063] 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.

[0064] The positive electrode protective layer 223 is in contact with the positive electrode core 221 and is formed on one end of the positive electrode active material layer 222 in the width direction. 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 larger electrical resistance than the positive electrode active material layer 222.

[0065] 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.

[0066] The positive electrode substrate 221 coated with the positive electrode active material layer slurry and the positive electrode protective layer slurry is dried, and the NMP contained in the positive electrode active material layer slurry and the positive electrode protective layer slurry is removed, thereby forming the positive electrode active material layer 222 and the positive electrode protective layer 223. The positive electrode active material layer 222 is then compressed to form a positive electrode base plate 220S including the positive electrode substrate 221, the positive electrode active material layer 222, and the positive electrode protective layer 223. The positive electrode base plate 220S is cut into a predetermined shape to form the positive electrode plate 220. The positive electrode base plate 220S can be cut by laser processing using energy beam irradiation, mold processing, cutter processing, or the like.

[0067] As shown in FIG. 11 , a plurality of positive electrode tabs 220B each made of a positive electrode core 221 is provided at one end in the width direction of a positive electrode plate 220 formed from a positive electrode original plate 220S. When the positive electrode plate 220 is wound, the plurality of positive electrode tabs 220B are stacked to form a positive electrode tab group 220A. The position and length in the protruding direction of each of the plurality of positive electrode tabs 220B are adjusted as appropriate, taking into account the state in which the positive electrode tab group 220A is connected to the positive electrode current collector 320. The shape of the positive electrode tabs 220B is not limited to the example shown in FIG. 11 .

[0068] The base of each of the positive electrode tabs 220B is provided with a positive electrode protective layer 223. The positive electrode protective layer 223 does not necessarily have to be provided at the base of the positive electrode tab 220B.

[0069] In a typical example, the thickness of the negative electrode tab 210B (one piece) is smaller than the thickness of the positive electrode tab 220B (one piece). In this case, the thickness of the negative electrode tab group 210A is smaller than the thickness of the positive electrode tab group 220A.

[0070] (Connection structure between electrode body 200 and current collector 300) Fig. 12 is a diagram showing the electrode body 200 and current collector 300 removed from the secondary battery 1. As shown in Fig. 12, the electrode body 200 is formed by stacking two electrode bodies 201 and 202, each of which is a wound electrode body. The example shown in Fig. 12 shows a structure in which two wound electrode bodies are stacked, but the electrode body 200 may be composed of one wound electrode body, three or more wound electrode bodies, or a stacked electrode body.

[0071] The negative electrode tab group 210A is joined to the negative electrode current collector 310 at a joint 310A, and the positive electrode tab group 220A is joined to the positive electrode current collector 320 at a joint 320A. The joints 310A, 320A can be formed by, for example, ultrasonic welding, resistance welding, laser welding, crimping, or the like. The joints 310A, 320A form conductive paths between the negative electrode tab group 210A and the positive electrode tab group 220A and the negative electrode terminal 131 and the positive electrode terminal 132.

[0072] (Connection structure between electrode body 200 and negative electrode current collector 310) Fig. 13 is a diagram showing a connection structure between a negative electrode tab group 210A and a negative electrode current collector 310. Fig. 14 and Fig. 15 are a front view and a cross-sectional view, respectively, of the connection structure shown in Fig. 13.

[0073] 13 to 15 , the negative electrode current collector 310 is connected to the negative electrode terminal 131 between the electrode body 200 and the sealing plate 121. The negative electrode current collector 310 includes a first conductive member 311 and a second conductive member 312. The first conductive member 311 and the second conductive member 312 are joined at a joint 313.

[0074] The negative electrode tab group 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 bonding, resistance welding, laser welding, caulking, or the like.

[0075] 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.

[0076] The negative electrode terminal 131 is attached to the sealing plate 121 via a resin insulating member 410A. The negative electrode terminal 131 is exposed to the outside of the sealing plate 121 and is provided so as to reach the second conductive member 312 of the negative electrode current collector 310 provided on the inside side of the sealing plate 121. The negative electrode terminal 131 and the second conductive member 312 can be connected by, for example, ultrasonic bonding, resistance welding, laser welding, or crimping. In the present embodiment, a through hole is provided in the second conductive member 312, the negative electrode terminal 131 is inserted into the through hole, the negative electrode terminal 131 is crimped onto the second conductive member 312, and then the crimped portion and the second conductive member 312 are welded at a joint 131A, thereby connecting the negative electrode terminal 131 and the second conductive member 312.

[0077] The assembly procedure for each component is as follows: first, the negative electrode terminal 131 and the second conductive member 312 are attached to the sealing plate 121 together with the insulating members 410 and 410A. Next, the first conductive member 311 connected to the electrode body 200 is attached to the second conductive member 312. At this time, the first conductive member 311 is placed on the insulating member 410 so that a portion of the first conductive member 311 overlaps the second conductive member 312. Next, the first conductive member 311 and the second conductive member 312 are welded together at the joint 313. Note that the insulating members 410 and 410A may be formed from a single member.

[0078] However, the negative electrode terminal 131 may be electrically connected to the sealing plate 121. Alternatively, the sealing plate 121 may serve as the negative electrode terminal 131.

[0079] 13 to 15 show an example of the negative electrode current collector 310 made up of two parts (the first conductive member 311 and the second conductive member 312), but the negative electrode current collector 310 may be made up of a single part.

[0080] (Step of inserting the electrode body 200) 16 is a diagram showing a process of inserting the electrode body 200 into the case body 110. As shown in FIG. 16, an insulating sheet 600 (electrode body holder) made of resin is placed between the electrode body 200 and the case body 110.

[0081] The insulating sheet 600 may be made of, for example, resin. More specifically, the material of the insulating sheet 600 may be, for example, polypropylene (PP), polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polyimide (PI), or polyolefin (PO).

[0082] The insulating sheet 600 does not necessarily have to cover the entire surface of the electrode assembly 200. The insulating sheet 600 preferably covers approximately 50% or more, and more preferably approximately 70% or more, of the area of ​​the outer surface of the electrode assembly. Of the six faces of the approximately rectangular parallelepiped (flat) electrode assembly 200, the insulating sheet 600 preferably covers the entire four faces other than at least the two faces on which the negative electrode tab group 210A and the positive electrode tab group 220A are formed.

[0083] Fig. 17 is a diagram showing a process of placing a spacer 510 between the sealing plate 121 and the electrode body 200. Fig. 18 is a cross-sectional view showing a state in which the spacer 510 has been placed between the sealing plate 121 and the electrode body 200.

[0084] 17 and 18, the negative electrode tab group 210A extending from the electrode body 200 toward the sealing plate 121 is curved from the center toward the edge in the Y-axis direction of the sealing plate 121, and then folded back toward the center. A spacer 510 is arranged to accommodate the curved negative electrode tab group 210A (curved portion).

[0085] The spacer 510 includes a first spacer 511 and a second spacer 512. The first spacer 511 and the second spacer 512 are engaged with each other by sliding them along the Y-axis direction from the end side toward the center of the sealing plate 121. This fixes the spacer 510 to the sealing plate 121 via the insulating member 410, increasing the stability of the position of the spacer 510.

[0086] 18, the spacer 510 forms an internal space for accommodating the negative electrode current collector 310, and the tip portion of the negative electrode tab group 210A is also accommodated in the internal space of the spacer 510. The spacer 510 has a hole that allows the negative electrode tab group 210A to pass through.

[0087] The material of the spacer 510 is not particularly limited, but it is preferable to use an insulating material such as resin. More specifically, it is preferable to use a sheet made of polyolefin (PO). Furthermore, an insulating sheet 600 may be interposed between the spacer 510 and the electrode assembly 200.

[0088] 16 again, in the method for manufacturing secondary battery 1 according to the present embodiment, electrode body 200 is inserted into case body 110 in a state where electrode body 200 is covered with insulating sheet 600. This makes it possible to suppress damage to electrode body 200 when it is inserted into case body 110.

[0089] During the step of inserting the electrode body 200, the case body 110 can be held at a predetermined angle. As an example, it is preferable to insert the electrode body 200 while holding the case body 110 so that the X-axis direction (the width direction of the case body 110) intersects with the horizontal direction at an angle of approximately ±45° or less. For example, the electrode body 200 can be inserted into the case body 110 with the case body 110 tilted in the vertical direction so that the upper end of the opening 111, into which the electrode body 200 is inserted, is positioned higher than the upper end of the opening 112.

[0090] The step of inserting the electrode body 200 may be performed in such a manner that the electrode body 200 is pushed in from the opening 111 side, or in such a manner that the electrode body 200 is pulled from the opening 112 side.

[0091] (Connection structure between electrode body 200 and positive electrode current collector 320) 19 is a diagram showing a connection structure between a positive electrode tab group 220A and a positive electrode current collector 320. FIG. 20 is a cross-sectional view of the connection structure shown in FIG.

[0092] 19 and 20, the positive electrode current collector 320 is provided on the inner surface side of the sealing plate 122 and is connected to the electrode assembly 200 and the positive electrode terminal 132. The positive electrode current collector 320 includes a first conductive member 321 (first component) and a second conductive member 322 (second component). The first conductive member 321 and the second conductive member 322 are joined at a joint 323. The first conductive member 321 and the second conductive member 322 are attached to the inner surface side of the sealing plate 122 via an insulating member 420 made of resin.

[0093] The first conductive member 321 has a step portion 321A. The step portion 321A extends in the long side direction (Z-axis direction) of the rectangular sealing plate 122. As shown in FIG. 20 , in a region (first region) on one side (left side in FIG. 20 ) of the step portion 321A, the first conductive member 321 is provided so as to follow the sealing plate 122 and is joined to the positive electrode tab group 220A (joint portion 320A). In a region (second region) on the other side (right side in FIG. 20 ) of the step portion 321A, the first conductive member 321 is provided so as to overlap with the second conductive member 322. These configurations are similar on the negative electrode side (see FIGS. 13 to 15 ).

[0094] 19 and 20 show the shape of the positive electrode tab group 220A before it is curved, but in the completed secondary battery 1, the positive electrode tab group 220A is housed in a curved state in the case body 110. Before the electrode body 200 is housed in the case body 110, it is preferable to curve (shape) the positive electrode tab group 220A to a state close to its final shape.

[0095] The positive electrode tab group 220A is joined to a first conductive member 321 of the positive electrode current collector 320 at a joint 320A. The first conductive member 321 is connected to a second conductive member 322 at a joint 323. The joint 323 can be formed by, for example, ultrasonic bonding, resistance welding, laser welding, caulking, or the like.

[0096] The positive electrode terminal 132 is attached to the sealing plate 122 via a resin insulating member 420A. The positive electrode terminal 132 is exposed to the outside of the sealing plate 122 and is provided so as to reach the second conductive member 322 of the positive electrode current collector 320 provided on the inside side of the sealing plate 122. The positive electrode terminal 132 and the second conductive member 322 can be connected by, for example, ultrasonic bonding, resistance welding, laser welding, crimping, or the like. In the present embodiment, a through hole is provided in the second conductive member 322, the positive electrode terminal 132 is inserted into the through hole, the positive electrode terminal 132 is crimped onto the second conductive member 322, and then the crimped portion and the second conductive member 322 are welded at a joint 132A, thereby connecting the positive electrode terminal 132 and the second conductive member 322.

[0097] The assembly procedure for each component is as follows: first, the positive electrode terminal 132 and the second conductive member 322 are attached to the sealing plate 122 together with the insulating members 420 and 420A. Next, the first conductive member 321 connected to the electrode body 200 is attached to the second conductive member 322. At this time, the first conductive member 321 is placed on the insulating member 420 so that a portion of the first conductive member 321 overlaps the second conductive member 322. Next, the first conductive member 321 and the second conductive member 322 are welded together at the joint 323. Note that the insulating members 420 and 420A may be formed from a single member.

[0098] However, the positive electrode terminal 132 may be electrically connected to the sealing plate 122. Alternatively, the sealing plate 122 may serve as the positive electrode terminal 132.

[0099] 19 and 20 show an example of the positive electrode current collector 320 made up of two parts (first conductive member 321 and second conductive member 322), but the positive electrode current collector 320 may be made up of a single part.

[0100] (Modified spacer) Fig. 21 is a diagram showing modified examples of spacers disposed between sealing plates 121, 122 and electrode assembly 200. Fig. 22 and Fig. 23 are diagrams showing negative electrode side spacer 510 and positive electrode side spacer 520 shown in Fig. 21, respectively.

[0101] 21 to 23 each have through holes 510A and 520A that communicate with the liquid inlet holes 141 and 142, respectively, through holes 510B and 520B that communicate with the gas release valves 151 and 152, recesses 510C and 520C for avoiding interference with the negative electrode current collector 310 and the positive electrode current collector 320, and recesses 510D and 520D for avoiding interference with the negative electrode tab group 210A and the positive electrode tab group 220A. Note that the spacers 510 and 520 do not necessarily have to have the same type of structure; for example, a through hole or a recess may be provided in only one of the spacers, or the spacers may be made of different materials.

[0102] By forming through-holes 510A, 510B, 520A, 520B and recesses 510C, 510D, 520C, 520D in spacers 510, 520, spacers 510, 520 can be arranged inside case body 110 while avoiding interference with electrode assembly 200 and current collector 300 and without impeding the functions of liquid inlet holes 141, 142 and gas release valves 151, 152. Spacers 510, 520 may be fixed (by fitting, bonding, welding, etc.) to sealing plates 121, 122, for example.

[0103] The structures of the through holes 510A, 510B, 520A, 520B and the recesses 510C, 510D, 520C, 520D are not limited to those shown in Figures 21 to 23. For example, cutouts or slits may be provided instead of the through holes.

[0104] (Electrode tab structure) Next, the structures of the negative electrode tab 210B and the positive electrode tab 220B will be described with reference to FIGS.

[0105] As shown in Fig. 24, each of the multiple negative electrode tabs 210B included in the negative electrode tab group 210A is curved, and the foil-assembled negative electrode tabs 210B reach the joint 310A. Therefore, the lengths of the multiple negative electrode tabs 210B are different from one another. Fig. 24 schematically shows the longest negative electrode tab 210B1 and the shortest negative electrode tab 210B2 in the negative electrode tab group 210A. Fig. 25 shows the length L1 (maximum value of the first length) of the negative electrode tab 210B1 (longest negative electrode tab 210B) from the base of the negative electrode tab group 210A to the joint 310A.

[0106] As shown in Fig. 25, each of the multiple positive electrode tabs 220B included in the positive electrode tab group 220A is curved, and the foil-assembled positive electrode tabs 220B reach the joint 320A. Therefore, the multiple positive electrode tabs 220B have different lengths. Fig. 25 schematically shows the longest positive electrode tab 220B1 and the shortest positive electrode tab 220B2 in the positive electrode tab group 220A. Fig. 26 shows the length L2 (maximum value of the second length) of the positive electrode tab 220B1 (longest positive electrode tab 220B) from the base of the positive electrode tab group 220A to the joint 320A.

[0107] 25 and 27 are measured with the negative electrode plate 210 and the positive electrode plate 220 extending in a single plane and the negative electrode tab 210B1 and the positive electrode tab 220B1 not bent. In other words, the lengths L1 and L2 shown in Figures 25 and 27 are lengths along the negative electrode tab 210B1 and the positive electrode tab 220B1, and are different from the linear distances when the negative electrode tab 210B1 and the positive electrode tab 220B1 are bent.

[0108] In the present embodiment, the length L1 (see FIG. 25) of the negative electrode tab 210B1 from the base of the negative electrode tab group 210A to the joint 310A and the length L2 (see FIG. 27) of the positive electrode tab 220B1 from the base of the positive electrode tab group 220A to the joint 320A satisfy the relationship L2 / L1>1.2 (more preferably, L2 / L1>1.5). In other words, the longest negative electrode tab 210B1 of the multiple negative electrode tabs 210B is formed shorter than the longest positive electrode tab 220B1 of the multiple positive electrode tabs 220B.

[0109] Furthermore, the length value L1' of the negative electrode tab 210B2 from the base of the negative electrode tab group 210A to the joint 310A (see FIG. 25 by replacing the negative electrode tab 210B1 with the negative electrode tab 210B2) and the length L2' of the positive electrode tab 220B2 from the base of the positive electrode tab group 220A to the joint 320A (see FIG. 27 by replacing the positive electrode tab 220B1 with the positive electrode tab 220B2) satisfy the relationship L2' / L1' > 1.5 (more preferably, L2' / L1' > 1.8). In other words, the shortest negative electrode tab 210B2 of the multiple negative electrode tabs 210B is formed shorter than the shortest positive electrode tab 220B2 of the multiple positive electrode tabs 220B.

[0110] In this way, the negative electrode tabs 210B are formed relatively short, and the positive electrode tabs 220B are formed relatively long in the secondary battery 1. The average length L10 from the base of the negative electrode tab group 210A to the joint 310A for the multiple negative electrode tabs 210B is smaller than the average length L20 from the base of the positive electrode tab group 220A to the joint 320A for the multiple positive electrode tabs 220B.

[0111] (Distance from the active material layer to the sealing plate) Fig. 28 is a diagram illustrating the distance from the sealing plate-side end of the electrode active material layer to the sealing plates 121, 122. Referring to Fig. 28, the distance D2 from the sealing plate 122-side end of the positive electrode active material layer 222 to the sealing plate 122 is greater than the distance D1 from the sealing plate 121-side end of the negative electrode active material layer 212 to the sealing plate 121. In other words, a larger space is formed between the active material layer and the sealing plate on the positive electrode side (sealing plate 122 side) than on the negative electrode side (sealing plate 121 side).

[0112] In this case, the electrolyte solution is preferably injected into the exterior housing 100 from the injection hole 142 on the positive electrode side. By injecting the electrolyte solution from the positive electrode side, where a relatively large gap is formed, the space for temporarily storing the electrolyte solution can be made larger, thereby making the injection process more efficient. In addition, the blowing out of the electrolyte solution from the injection hole 142 can be effectively prevented. Furthermore, even when a portion of the sealing member that seals the injection hole 142 protrudes inside the sealing plate 122, contact between the protruding sealing member and the electrode body 200 can be more effectively prevented. A member that partially includes a resin seal portion and a rubber portion may be used as this sealing member.

[0113] (Manufacturing process of secondary battery 1) Fig. 29 is a flow diagram showing each step of the manufacturing method of the secondary battery 1. As shown in Fig. 29, in S10, the case body 110 is prepared. Next, in S20, the electrode body 200 is fabricated. In S30, the electrode terminals on the sealing plates 121, 122 are electrically connected to the electrode tab group of the electrode body 200. In the example of Fig. 29, first, the negative electrode terminal 131 and the negative electrode tab group 210A are electrically connected (S31), and then the positive electrode terminal 132 and the positive electrode tab group 220A are electrically connected (S32).

[0114] More specifically, after electrically connecting the negative electrode terminal 131 and the negative electrode tab group 210A (S31), first, the first conductive member 321 of the positive electrode current collector 320 is joined to the positive electrode tab group 220A (S32A), and then a spacer 510 is placed between the negative electrode side sealing plate 121 and the electrode assembly 200 (S41). Thereafter, the electrode assembly 200 is inserted into the case body 110 (S50). After the electrode assembly 200 is inserted into the case body 110, the first conductive member 321 and the second conductive member 322 are joined to electrically connect the positive electrode terminal 132 and the positive electrode tab group 220A (S32B), and a spacer 520 is placed between the positive electrode side sealing plate 122 and the electrode assembly 200 (S42).

[0115] After the connection of the electrode terminals and the electrode tab group (S30), the installation of the spacers 510 and 520 (S40), and the insertion of the electrode body 200 (S50) are all completed in the above-described procedure, the openings 111 and 112 are sealed with the sealing plates 121 and 122, respectively (S60). The sealing step with the sealing plates 121 and 122 is performed by, for example, laser welding.

[0116] In the present technology, the order of connecting the electrode terminal and the electrode tab group (S30), placing the spacers 510, 520 (S40), and inserting the electrode assembly 200 (S50) is not limited to the example in Fig. 29 and can be changed as appropriate. For example, after inserting the electrode assembly 200 (S50), or during the insertion of the electrode assembly 200 (S50), the electrical connection between the negative electrode terminal 131 and the negative electrode tab group 210A (S31) and the placement of the spacer 510 (S41) may be performed.

[0117] 29, the step (S61) of sealing opening 111 with sealing plate 121 on the negative electrode side is performed, followed by the step (S62) of sealing opening 112 with sealing plate 122 on the positive electrode side, but the step (S61) of sealing opening 111 with sealing plate 121 may be performed after the step (S62) of sealing opening 112 with sealing plate 122. Furthermore, at least some of the steps (S61, S62) of sealing with sealing plates 121, 122 may be performed simultaneously.

[0118] (summary) The secondary battery 1 and the manufacturing method thereof according to the present embodiment will be briefly described below, however, the scope of the present technology is not necessarily limited to the examples in the present embodiment.

[0119] The secondary battery 1 according to this embodiment includes an electrode body 200 that includes a negative electrode plate 210 (first electrode) and a positive electrode plate 220 (second electrode), and has a negative electrode tab group 210A (first electrode tab group) at one end and a positive electrode tab group 220A (second electrode tab group) at the other end, an outer casing 100 that houses the electrode body 200, and a negative electrode terminal 131 (first electrode terminal) and a positive electrode terminal 132 (second electrode terminal) provided on the outer casing 100.

[0120] Exterior body 100 includes case main body 110 having opening 111 (first opening) and opening 112 (second opening) facing opening 111, sealing plate 121 (first sealing plate) having negative electrode terminal 131 provided therein and sealing opening 111, and sealing plate 122 (second sealing plate) having positive electrode terminal 132 provided therein and sealing opening 112. Negative electrode terminal 131 and negative electrode tab group 210A are electrically connected, and positive electrode terminal 132 and positive electrode tab group 220A are electrically connected. The negative electrode tab group 210A has a joint portion 310A (first joint portion) joined to a first conductive member 311 (first other component) of the negative electrode current collector 310 (first current collector) so as to form a conductive path to the negative electrode terminal 131, and the positive electrode tab group 220A has a joint portion 320A (second joint portion) joined to a first conductive member 321 (second other component) of the positive electrode current collector 320 (second current collector) so as to form a conductive path to the positive electrode terminal 132. The electrode tab group may also be joined to a sealing plate or an electrode terminal.

[0121] As shown in FIG. 29 , the method for manufacturing the secondary battery 1 according to the present embodiment includes: a step (S10) of preparing a case body 110 having an opening 111 and an opening 112 facing the opening 111; a step (S20) of fabricating an electrode body 200 including a negative electrode plate 210 and a positive electrode plate 220, the electrode body 200 having, at one end, a negative electrode tab group 210A (first electrode tab group) including a negative electrode tab 210B electrically connected to the negative electrode plate 210, and a positive electrode tab 220B including, at the other end, a positive electrode tab 220B (second electrode tab group) electrically connected to the positive electrode plate 220; a step (S31) of electrically connecting a negative electrode terminal 131 provided on a sealing plate 121 to the negative electrode tab group 210A; the electrode assembly 200 into the case body 110 (S50); after the electrode assembly 200 has been inserted into the case body 110, a step (S32B) of joining the first conductive member 321 and the second conductive member 322 to electrically connect the positive electrode terminal 132 and the positive electrode tab group 220A; a step (S42) of placing the spacer 520 between the positive electrode side sealing plate 122 and the electrode assembly 200; a step (S61) of sealing the opening 111 with the sealing plate 121; and a step (S62) of sealing the opening 112 with the sealing plate 122. The negative electrode tab group 210A may include multiple negative electrode tabs 210B1 having the same length (first length) from the base of the negative electrode tab group 210A to the joint 310A. The positive electrode tab group 220A may include multiple positive electrode tabs 220B1 having the same length (second length) from the base of the positive electrode tab group 220A to the joint 320A.

[0122] The step (S31) of electrically connecting the negative electrode terminal 131 and the negative electrode tab group 210A includes joining the negative electrode tab group 210A to the first conductive member 311 of the negative electrode current collector 310 at the joint 310A. The step (S32) of electrically connecting the positive electrode terminal 132 and the positive electrode tab group 220A includes joining the positive electrode tab group 220A to the first conductive member 321 of the positive electrode current collector 320 at the joint 320A.

[0123] In the secondary battery 1, the negative electrode tab group 210A includes a plurality of negative electrode tabs 210B (first electrode tabs) having different lengths (first lengths) from the base of the negative electrode tab group 210A to the joint 310A, and the positive electrode tab group 220A includes a plurality of positive electrode tabs 220B (second electrode tabs) having different lengths (second lengths) from the base of the positive electrode tab group 220A to the joint 320A. For the longest electrode tab, the length L1 of the negative electrode tab 210B1 from the base of the negative electrode tab group 210A to the joint 310A and the length L2 of the positive electrode tab 220B1 from the base of the positive electrode tab group 220A to the joint 320A satisfy the relationship L2 / L1 > 1.2 (more preferably, L2 / L1 > 1.5).

[0124] Furthermore, for the shortest electrode tab, the length L1' of the negative electrode tab 210B2 from the base of the negative electrode tab group 210A to the joint 310A and the length L2' of the positive electrode tab 220B2 from the base of the positive electrode tab group 220A to the joint 320A satisfy the relationship L2' / L1'>1.5 (more preferably, L2' / L1'>1.8).

[0125] The tip ends of the curved portions of the negative electrode tab group 210A and the positive electrode tab group 220A are joined to the negative electrode current collector 310 and the positive electrode current collector 320 to form joints 310A and 320A, respectively. The region of the negative electrode current collector 310 where joint 310A is located is disposed along the sealing plate 121, and the region of the positive electrode current collector 320 where joint 320A is located is disposed along the sealing plate 122. However, the negative electrode current collector 310 and the positive electrode current collector 320 do not necessarily extend parallel to the sealing plates 121 and 122, and an inclination of, for example, about ±30° is acceptable.

[0126] In the direction connecting the sealing plates 121 and 122 (X-axis direction), a distance D1 (first distance) from the end of the negative electrode active material layer 212 (first active material layer) on the sealing plate 121 side to the sealing plate 121 and a distance D2 (second distance) from the end of the positive electrode active material layer 222 (second active material layer) on the sealing plate 122 side to the sealing plate 122 satisfy the relationship D2>D1 (more preferably, D2 / D1>1.2, and even more preferably, D2 / D1>1.5).

[0127] A spacer 510 (first spacer) and a spacer 520 (second spacer) are respectively disposed between the sealing plate 121 and the electrode body 200, and between the sealing plate 122 and the electrode body 200. The spacers 510 and 520 are preferably formed so as to be able to contact a region where the negative tab group 210A and the positive tab group 220A of the electrode body 200 are not formed.

[0128] For example, the thickness of one negative tab 210B is about 5 μm or more and 20 μm or less, and the thickness of one positive tab 220B is about 5 μm or more (preferably 8 μm or more) and 20 μm or less. Here, it is preferable that the thickness (second thickness) of each of the plurality of positive tabs 220B is larger than the thickness (first thickness) of each of the plurality of negative tabs 210B. As an example, it is preferable that the thickness of one positive tab 220B is about 1.2 times or more (more preferably about 1.5 times or more) the thickness of one negative tab 210B.

[0129] The number of negative tabs 210B (first number S1) constituting the negative tab group 210A and the number of positive tabs 220B (second number S2) constituting the positive tab group 220A may be the same or different. As an example, it is preferable that 0.5 < S1 / S2 < 1.5 (more preferably, 0.8 < S1 / S2 < 1.2).

[0130] In the present embodiment, the step (S31) of electrically connecting the negative terminal 131 and the negative tab group 210A is performed before the step (S50) of inserting the electrode body 200 into the case body 110, but the scope of the present technology is not limited thereto. The step (S31) of electrically connecting the negative terminal 131 and the negative tab group 210A may be performed during the step (S50) of inserting the electrode body 200 into the case body 110, or may be performed after the step (S50) of inserting the electrode body 20 into the case body 110.

[0131] Furthermore, in this embodiment, prior to the step (S50) of inserting the electrode body 200 into the case body 110, the first conductive member 311 of the negative electrode current collector 310 is joined to the negative electrode tab group 210A, and the first conductive member 321 of the positive electrode current collector 320 is joined to the positive electrode tab group 220A, but the scope of the present technology is not limited thereto.

[0132] The electrode body 200 may be covered with an insulating sheet 600 before being inserted into the case body 110. However, in the present technology, the insulating sheet 600 covering the electrode body 200 is not necessarily required.

[0133] When the electrolyte is poured into the case body 110 through the pouring hole 142 formed in the positive electrode side sealing plate 122, it is preferable to pour the electrolyte in a state in which the case body 110 is tilted so that the direction connecting the sealing plates 121, 122 (the X-axis direction) intersects with the horizontal direction and the positive electrode side sealing plate 122 is positioned vertically higher than the negative electrode side sealing plate 121. At this time, it is preferable to pour the electrolyte in a state in which a spacer 510 is disposed between the negative electrode side sealing plate 121 and the electrode assembly 200.

[0134] However, tilting case body 110 during injection is not essential in the present technology. Furthermore, the degree of tilt when tilting case body 110 to inject can also be changed as appropriate, and as one example, it is preferable to tilt the direction connecting sealing plates 121, 122 (X-axis direction) with respect to the horizontal direction by approximately 30° or more, more preferably by approximately 45° or more or 60° or more, and most preferably the direction connecting sealing plates 121, 122 (X-axis direction) is approximately vertical (tilted to an angle close to 90° with respect to the horizontal direction).

[0135] (Action and effect) According to the secondary battery 1 of this embodiment, the electrode body 200 is inserted into the case body 110 having openings 111 and 112 facing each other, and the negative terminal 131 and the positive terminal 132 are respectively provided on the sealing plates 121 and 122 that seal the openings 111 and 112, thereby reducing the height of the secondary battery 1 and improving the mountability of the secondary battery 1 in a vehicle.

[0136] Furthermore, the maximum length L1 from the base of the negative electrode tab group 210A to the joint portion 310A and the maximum length L2 from the base of the positive electrode tab group 220A to the joint portion 320A satisfy a predetermined relationship (L2 / L1>1.2). That is, the negative electrode tab 210B is formed relatively short, and the positive electrode tab 220B is formed relatively long.

[0137] By forming the negative electrode tab 210B relatively short, the volume that the electrode body 200 occupies in the space inside the case body 110 can be increased, and the energy density of the secondary battery 1 can be improved.

[0138] Furthermore, since the positive electrode tab 220B is formed relatively long, when the electrode body 200 is inserted into the case body from the positive electrode tab group 220A side, it is easy to join the positive electrode tab group 220A and the first conductive member 321 of the positive electrode current collector 320 on the opening 112 side of the case body 110.

[0139] In addition, by arranging the areas where the joints 310A, 320A between the negative electrode current collector 310 and the positive electrode current collector 320 and the negative electrode tab group 210A and the positive electrode tab group 220A are located along the sealing plates 121, 122, respectively, the energy density of the secondary battery 1 can be further improved.

[0140] Furthermore, by electrically connecting (S31) the relatively short negative electrode tab group 210A to the negative electrode terminal 131 before electrically connecting (S32) the relatively long positive electrode tab group 220A to the positive electrode terminal 132, damage to the negative electrode tab group 210A can be effectively suppressed.

[0141] Furthermore, when injecting the electrolyte with the case body 110 tilted so that the positive electrode side sealing plate 122 is positioned vertically above the negative electrode side sealing plate 121, by placing a spacer 510 between the negative electrode side sealing plate 121 and the electrode body 200, the spacer 510 can hold the electrode body 200, thereby effectively suppressing damage to the negative electrode tab group 210A.

[0142] As described above, the secondary battery 1 and the manufacturing method thereof according to this embodiment make it possible to stably and efficiently manufacture a highly reliable secondary battery with a high energy density.

[0143] 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]

[0144] 1 secondary battery, 100 outer casing, 110 case body, 110A joint, 111, 112 opening, 121, 122 sealing plate, 131 negative electrode terminal, 131A joint, 132 positive electrode terminal, 132A joint, 141, 142 liquid injection hole, 151, 152 gas release valve, 200, 201, 202 electrode body, 210 negative electrode plate, 210A negative electrode tab group, 210B negative electrode tab, 210S negative electrode base plate, 211 negative electrode core, 212 negative electrode active material layer, 220 positive electrode plate, 220A positive electrode tab group, 220B positive electrode tab, 220S positive electrode base plate, 221 positive electrode core, 222 positive electrode active material layer, 223 positive electrode protective layer, 300 Current collector, 310, negative electrode current collector, 310A, joint portion, 311, first conductive member, 312, second conductive member, 313, joint portion, 320, positive electrode current collector, 320A, joint portion, 321, first conductive member, 321A, step portion, 322, second conductive member, 323, joint portion, 410, 410A, 420, 420A, insulating member, 510, 520, spacer, 510A, 510B, 520A, 520B, through hole, 510C, 510D, 520C, 520D, recess, 511, first spacer, 512, second spacer, 600, insulating sheet.

Claims

1. an electrode body including a first electrode and a second electrode having a polarity different from that of the first electrode, the electrode body having a first electrode tab group electrically connected to the first electrode at a first end, and a second electrode tab group electrically connected to the second electrode at a second end opposite to the first end; a case for accommodating the electrode assembly; a first electrode terminal and a second electrode terminal provided on the case; The case is a case body having a first opening and a second opening opposite the first opening; a first sealing plate provided with the first electrode terminal and sealing the first opening; a second sealing plate provided with the second electrode terminal and sealing the second opening, the first electrode terminals and the first electrode tab group are electrically connected; the second electrode terminals and the second electrode tab group are electrically connected; the first electrode tab group has a first joining portion joined to a first other component so as to form a conductive path to the first electrode terminal; the second electrode tab group has a second joining portion joined to a second other component so as to form a conductive path to the second electrode terminal; the first electrode tab group includes a plurality of first electrode tabs having first lengths from bases of the first electrode tab group to the first joints that are different from one another; the second electrode tab group includes a plurality of second electrode tabs having second lengths from bases of the second electrode tab group to the second joints that are different from one another; a first maximum length L1 of the first electrode tab group and a second maximum length L2 of the second electrode tab group satisfy a relationship of L2 / L1>1.2, An electrolyte is contained in the case, a liquid injection hole is formed in the second sealing plate, and the liquid injection hole is sealed with a sealing member; the first electrode has a first active material layer, and the second electrode has a second active material layer; a first distance D1 from an end of the first active material layer on the first sealing plate side to the first sealing plate, and a second distance D2 from an end of the second active material layer on the second sealing plate side to the second sealing plate, in a direction connecting the first sealing plate and the second sealing plate, satisfying the relationship D2 > D1.

2. the first other component is housed in the case and is included in a first current collector that electrically connects the first electrode and the first electrode terminal; the second other component is housed in the case and is included in a second current collector that electrically connects the second electrode and the second electrode terminal; the first electrode tab group has a first curved portion, and a tip side of the first curved portion of the first electrode tab group is joined to the first current collector to form the first joint portion; 2. The secondary battery according to claim 1, wherein the second electrode tab group has a second curved portion, and a tip side of the second curved portion of the second electrode tab group is joined to the second current collector to form the second joint portion.

3. a region of the first current collector where the first joint portion is located is disposed along the first sealing plate, The secondary battery according to claim 2 , wherein a region of the second current collector where the second joint portion is located is disposed along the second sealing plate.

4. a first spacer disposed between the first sealing plate and the electrode body; The secondary battery according to claim 1 , further comprising a second spacer disposed between the second sealing plate and the electrode assembly.

5. 4. The secondary battery according to claim 1, wherein a minimum value L1' of the first length in the first electrode tab group and a minimum value L2' of the second length in the second electrode tab group satisfy a relationship of L2' / L1'>1.

5.

6. The secondary battery according to claim 1 , wherein the thickness of the second electrode tabs is greater than the thickness of the first electrode tabs.

7. preparing a case body having a first opening and a second opening opposite the first opening; a step of fabricating an electrode body including a first electrode and a second electrode having a polarity different from that of the first electrode, the electrode body having a first electrode tab group electrically connected to the first electrode at a first end, and a second electrode tab group electrically connected to the second electrode at a second end opposite to the first end; After preparing the electrode body, inserting the electrode body into the case body from the second end side through the first opening; a step of electrically connecting first electrode terminals provided on a first sealing plate to the first electrode tab group; a step of electrically connecting the first electrode terminals and the first electrode tab group, and then electrically connecting second electrode terminals provided on a second sealing plate and the second electrode tab group; a step of sealing the first opening with the first sealing plate after electrically connecting the first electrode terminal and the first electrode tab group; and sealing the second opening with the second sealing plate after electrically connecting the second electrode terminal and the second electrode tab group. the first electrode tab group has a first joining portion joined to a first other component so as to form a conductive path to the first electrode terminal; the second electrode tab group has a second joining portion joined to a second other component so as to form a conductive path to the second electrode terminal; the first electrode tab group includes a plurality of first electrode tabs having first lengths from bases of the first electrode tab group to the first joints that are different from one another; the second electrode tab group includes a plurality of second electrode tabs having second lengths from bases of the second electrode tab group to the second joints that are different from one another; a maximum first length L1 of the first electrode tab group and a maximum second length L2 of the second electrode tab group satisfying the relationship L2 / L1>1.

2.

8. The method for manufacturing a secondary battery according to claim 7 , wherein the first electrode terminals and the first electrode tab group are electrically connected to each other before the electrode body is inserted into the case body.

9. the first other component is housed in the case body and is included in a first current collector that electrically connects the first electrode and the first electrode terminal; 9. The method for manufacturing a secondary battery according to claim 7, wherein the second other component is included in a second current collector that is housed in the case body and electrically connects the second electrode and the second electrode terminal.

10. 9. The method for manufacturing a secondary battery according to claim 7, wherein the first other component and the first electrode tab group are joined and the second other component and the second electrode tab group are joined before the electrode body is inserted into the case body.

11. 9. The method for manufacturing a secondary battery according to claim 7, further comprising the step of covering the electrode assembly with an insulating electrode assembly holder before the electrode assembly is inserted into the case body.

12. injecting an electrolyte into the case body through an injection hole formed in the second sealing plate; further comprising a step of sealing the liquid injection hole with a sealing member, 9. The method for manufacturing a secondary battery according to claim 7 or 8, wherein the electrolyte is poured into the case body in a state in which the case body is tilted so that a direction connecting the first sealing plate and the second sealing plate intersects with a horizontal direction and the second sealing plate is positioned vertically above the first sealing plate.

13. The method for manufacturing a secondary battery according to claim 12 , wherein the electrolyte is poured into the case body with a spacer disposed between the first sealing plate and the electrode body.

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