Secondary battery and manufacturing method thereof

Abstract

To provide a secondary battery which has high reliability and can be stably manufactured.SOLUTION: A square case includes a first member 120, a second member 130, a third member 150, and a fourth member 160. The first member 120 forms a bottom surface portion 121 and a pair of first lateral portions 122. The second member 130 forms a top surface portion and is connected to end portions of the first lateral portions 122 in the first member 120. The third member 150 forms one of a pair of second lateral portions 140 and is connected to the first member 120 and the second member 130 at an end portion on a first side in a second direction. The fourth member 160 forms the other of the pair of second lateral portions 140, and is connected to the first member 120 and the second member 130 at an end portion of a second side opposite from the first side in the second direction. A first electrode terminal 301 is provided in the third member 150. A second electrode terminal 302 is provided in the fourth member 160.SELECTED DRAWING: Figure 21

Description

[Technical Field]

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

[0002] Japanese Patent No. 4537353 (Patent Document 1) is a prior art document that discloses the configuration of a secondary battery. The secondary battery described in Patent Document 1 includes an electrode group and a case. The electrode group is housed in the case. The case has openings at both ends for inserting the electrode group. The electrode group is inserted into the case through the openings. [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, when inserting the electrode assembly through the opening of the case, it is difficult to insert the electrode assembly into the case because the electrode assembly is surrounded by the case around the axis in the insertion direction of the electrode assembly.

[0005] An object of the present technology is to provide a highly reliable secondary battery that can be stably manufactured, and a method for manufacturing the same. [Means for solving the problem]

[0006] The present technology provides the following secondary battery. [1] An electrode body; a rectangular case that houses the electrode body and includes a bottom surface, an upper surface that faces the bottom surface, a pair of first side surfaces that face each other in a first direction, and a pair of second side surfaces that face each other in a second direction that is perpendicular to the first direction; a first electrode terminal and a second electrode terminal electrically connected to the electrode body; The case is a first member that constitutes the bottom surface portion and the pair of first side surface portions; a second member that forms the upper surface portion and is joined to an end of the first side surface portion of the first member; a third member that constitutes one of the pair of second side surface portions and is joined to an end of each of the first member and the second member at an end on a first side in the second direction; a fourth member that configures the other of the pair of second side surface portions and is joined to the end portions of the first member and the second member at end portions of a second side opposite to the first side in the second direction, The electrode body is a main body having 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 electrodes and positioned at an end of the first side relative to the main body; a second electrode tab group electrically connected to the second electrodes and located at an end of the second side relative to the main body portion; the first electrode terminal is provided on the third member, the second electrode terminal is provided on the fourth member, the first electrode tab group is electrically connected to the first electrode terminals; The second electrode tab group is electrically connected to the second electrode terminals. [2] the first electrode terminal is attached to the third member in a state of being electrically insulated from the third member; The secondary battery according to [1], wherein the second electrode terminal is attached to the fourth member in a state of being electrically insulated from the fourth member. [3] a first spacer located between the electrode body and the third member; The secondary battery according to [1] or [2], further comprising a second spacer between the electrode body and the fourth member. [4] The third member is a first portion that is positioned inside the case further than the first side ends of the first member and the second member and faces the first member and the second member from inside the case; A secondary battery according to any one of [1] to [3], having a second portion that abuts the first side end of the first member and the second member from the second direction.

[0007] The present technology provides the following method for manufacturing a secondary battery. [5] preparing an electrode assembly including a first electrode and a second electrode having a polarity different from that of the first electrode; preparing a first member having a bottom surface portion, a pair of first side surfaces rising from the bottom surface portion and facing each other in a first direction, a top surface opening facing the bottom surface portion, and a pair of side surface openings located between both ends of each of the pair of first side surfaces in a second direction perpendicular to the first direction; providing a second member; attaching a first electrode terminal to a third member; attaching a second electrode terminal to the fourth member; a step of electrically connecting a first electrode tab group electrically connected to the first electrodes of the electrode body to the first electrode terminals; a step of electrically connecting a group of second electrode tabs electrically connected to the second electrodes of the electrode body to the second electrode terminals; inserting the electrode body between the pair of first side surface portions of the first member; a step of inserting the electrode body between the pair of first side surface portions, and then joining the second member to each end of the pair of first side surface portions, and closing the top surface opening; after the step of closing the top surface opening, a step of joining the third member to the first member and the second member to close one of the pair of side surface openings, and joining the fourth member to the first member and the second member to close the other of the pair of side surface openings, thereby closing the pair of side surface openings. [6] [5] A method for manufacturing a secondary battery described in [5], wherein at least a part of the process of closing the pair of side openings includes rotating the first member and the second member while holding the first member and the second member rotatably around an axis in the second direction. [7] [6] The method for manufacturing a secondary battery described in [6], wherein at least a part of the step of closing the pair of side openings includes pressing the first member along the first direction to deform the first member and sandwiching the electrode body between the first members. [8] The method for manufacturing a secondary battery according to [6] or [7], wherein the step of closing the pair of side openings includes temporarily joining the third member and the fourth member to the first member and the second member. [9] The method for manufacturing a secondary battery according to any one of [5] to [8], wherein in the step of closing the pair of side openings, at least a portion of the joining of the third member and the joining of the fourth member are performed simultaneously.

[10] The method for manufacturing a secondary battery according to any one of [5] to [9], wherein the step of inserting the electrode body includes inserting the electrode body toward the bottom surface portion. [Effects of the Invention]

[0008] According to the present technology, it is possible to provide a highly reliable secondary battery that can be stably manufactured, and a method for manufacturing the same. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a front view illustrating a configuration of a secondary battery according to an 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]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 front view of a connection structure between a negative electrode tab group and a negative electrode current collector. [Figure 14] FIG. 2 is a cross-sectional view of a connection structure between a negative electrode tab group and a negative electrode current collector. [Figure 15] FIG. 10 is a diagram showing a step of arranging a spacer between the third member and the electrode body. [Figure 16] 1 is a perspective view showing a component configuration of a case included in a secondary battery according to an embodiment; [Figure 17] FIG. 10 is a perspective view showing a state in which the members of the case are joined together. [Figure 18] 4 is a cross-sectional view showing a state in which a first member and a second member are fitted together in the case. FIG. [Figure 19] 10 is a cross-sectional view showing a state in which a third member and a fourth member are joined to a first member and a second member of a case. FIG. [Figure 20] 1 is a flowchart illustrating a method for manufacturing a secondary battery according to an embodiment. [Figure 21] FIG. 10 is a perspective view showing a state in which an electrode body is being inserted into a first member of the case. [Figure 22] 1 is a perspective view illustrating a method for joining a first member, a second member, and a third member of a case included in a secondary battery according to one embodiment. [Figure 23]10 is a side view showing a state immediately after starting to join the first and second members of the case to the third member. FIG. [Figure 24] 10 is a side view showing a state in which the short side portions of the first and second members and the third member of the case are joined while being rotated. FIG. [Figure 25] 10 is a side view showing a state in which the long side portions of the first and second members and the third member of the case are joined while being rotated. FIG. [Figure 26] FIG. 10 is a cross-sectional view showing a fitted state between a first member and a second member in a case according to a first modified example of the embodiment. [Figure 27] FIG. 10 is a cross-sectional view showing a fitted state between a first member and a second member in a case according to a second modified example of the embodiment. [Figure 28] FIG. 11 is a perspective view showing a joined state between a first member and a third member of a case included in a secondary battery according to a third modified example of the embodiment. 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 as the second direction, the Y direction as the first direction is the short side direction of the electrode body that is perpendicular to the second direction and seen from the second direction, and the Z direction as the long side direction of the electrode body that is perpendicular to the second direction and seen from the second 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 in some places.

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

[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 5, 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 configured of a first member 120 and a second member 130, a third member 150, and a fourth member 160, which will be described later.

[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] 1 and 2, a third member 150 and a fourth member 160 are provided at both ends of the case body 110. The third member 150 and the fourth member 160 function as sealing plates that seal the opening of the case body 110.

[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] 3, a first opening 113 is provided at the end of the first side in the second direction (X direction) of the case body 110. The first opening 113 is sealed by a third member 150. The first opening 113 and the third member 150 have a substantially rectangular shape with the Y direction as the short side direction and the Z direction as the long side direction.

[0025] The third member 150 is provided with a negative electrode terminal 301 (first electrode terminal), a liquid inlet 154, and a gas release valve 155. The positions of the negative electrode terminal 301, the liquid inlet 154, and the gas release valve 155 can be changed as appropriate.

[0026] 4, a second opening 114 is provided at the end of the second side opposite the first side in the second direction (X direction) of the case body 110. The second opening 114 is sealed by a fourth member 160. The second opening 114 and the fourth member 160 have a substantially rectangular shape with the Y direction as the short side direction and the Z direction as the long side direction.

[0027] The fourth member 160 is provided with a positive electrode terminal 302 (second electrode terminal), a liquid inlet 164, and a gas exhaust valve 165. The positions of the positive electrode terminal 302, the liquid inlet 164, and the gas exhaust valve 165 can be changed as appropriate.

[0028] The third member 150 and the fourth member 160 are made of metal. Specifically, the third member 150 and the fourth member 160 are made of aluminum, an aluminum alloy, iron, an iron alloy, or the like.

[0029] In this embodiment, the thickness of each of the third member 150 and the fourth member 160 is greater than the thickness (plate thickness) of the case body 110. This reduces the thermal influence when forming the bonding portions 170a, 170b, 171a, and 171b (described later) in the third member 150 and the fourth member 160, which occupy a smaller volume than the case body 110, and makes it possible to suppress holes from being formed during bonding.

[0030] The negative electrode terminal 301 is electrically connected to the negative electrode of the electrode body 200. The negative electrode terminal 301 is provided on the outer surface of the third member 150, that is, on the outer surface of the case 100.

[0031] The positive electrode terminal 302 is electrically connected to the positive electrode of the electrode body 200. The positive electrode terminal 302 is provided on the outer surface of the fourth member 160, that is, on the outer surface of the case 100.

[0032] 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.

[0033] 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.

[0034] The liquid inlet holes 154 and 164 are sealed with a sealing member (not shown), which may be, for example, a blind rivet or other metal member.

[0035] The gas exhaust valves 155, 165 break when the pressure inside the case 100 reaches or exceeds a predetermined value, and exhaust the gas inside the case 100 to the outside.

[0036] 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, but 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 made of, for example, 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.

[0037] 5, case 100 houses electrode assembly 200. Electrode assembly 200 is housed in case 100 so that its winding axis is parallel to the X direction.

[0038] Specifically, one or more wound electrode bodies are housed together with an electrolytic solution (electrolyte), not shown, inside an insulating sheet (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 LiPF6 is dissolved at a concentration of 1.2 mol / L. Note that a solid electrolyte may be used instead of the electrolytic solution.

[0039] The electrode assembly 200 includes a main body portion, a negative electrode tab group 220 (first electrode tab group), and a positive electrode tab group 250 (second electrode tab group).

[0040] The main body portion includes a negative electrode plate 210 (first electrode) and a positive electrode plate 240 (second electrode), which will be described later. The negative electrode tab group 220 is located at the end of a first side of the electrode assembly 200 in the second direction (X direction) relative to the main body portion. In this embodiment, the first side is the third member 150 side. The positive electrode tab group 250 is located at the end of a second side in the second direction (X direction) relative to the main body portion. In this embodiment, the second side is the fourth member 160 side.

[0041] The negative electrode tab group 220 and the positive electrode tab group 250 are formed so as to protrude from the center portion of the electrode body 200 toward the third member 150 or the fourth member 160, respectively.

[0042] The current collector 400 includes a negative electrode current collector 410 (first current collector) and a positive electrode current collector 420 (second current collector). The negative electrode current collector 410 and the positive electrode current collector 420 are 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 collector 400.

[0043] The negative electrode current collector 410 is disposed on the third member 150 via a resin insulating member. The negative electrode current collector 410 is electrically connected to the negative electrode tab group 220 and the negative electrode terminal 301. This electrically connects the negative electrode tab group 220 to the negative electrode terminal 301. The negative electrode current collector 410 is made of a conductive material (more specifically, a metal), and may be made of, for example, copper or a copper alloy.

[0044] The positive electrode current collector 420 is disposed on the fourth member 160 via a resin insulating member. The positive electrode current collector 420 is electrically connected to the positive electrode tab group 250 and the positive electrode terminal 302. As a result, the positive electrode tab group 250 is electrically connected to the positive electrode terminal 302. The positive electrode current collector 420 is made of a conductive material (more specifically, a metal), and may be made of, for example, aluminum or an aluminum alloy.

[0045] (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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] As shown in FIG. 8, a plurality of negative electrode tabs 230 made of negative electrode cores 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 negative electrode tab group 220. As a result, the negative electrode tab group 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 adjusted as appropriate, taking into consideration the state in which the negative electrode tab group 220 is connected to the negative electrode current collector 410. The shape of the negative electrode tabs 230 is not limited to the example shown in FIG. 8.

[0051] FIG. 9 is a front view showing a positive electrode plate 240S before the positive electrode plate 240 (second electrode) is formed, FIG. 10 is a cross-sectional view of the positive electrode plate 240S shown in FIG. 9 taken along line XX, and FIG. 11 is a front view showing a positive electrode plate 240 formed from the positive electrode plate 240S.

[0052] 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. 9 and 10 , 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] As shown in FIG. 11 , a plurality of positive electrode tabs 260 made of positive electrode cores 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 positive electrode tab group 250. As a result, the positive electrode tab group 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 positive electrode tab group 250 is connected to the positive electrode current collector 420. Note that the shape of the positive electrode tab 260 is not limited to the example shown in FIG. 11 .

[0059] 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.

[0060] 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 negative electrode tab group 220 is smaller than the thickness of the positive electrode tab group 250.

[0061] (Connection structure between electrode body 200 and current collector 400) Fig. 12 is a diagram showing the electrode body 200 and current collector 400 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.

[0062] The negative electrode tab group 220 is joined to the negative electrode current collector 410 at a joint 434 , and the positive electrode tab group 250 is joined to the positive electrode current collector 420 at a joint 454 .

[0063] (Insulation sheet configuration) Between the electrode body 200 and the case body 110, an insulating sheet (electrode body holder) made of resin (not shown) is arranged.

[0064] The insulating sheet may be made of, for example, resin. More specifically, the material of the insulating sheet may be, for example, polypropylene (PP), polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polyimide (PI), or polyolefin (PO).

[0065] The insulating sheet does not necessarily have to cover the entire surface of the electrode assembly 200. The insulating sheet 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 substantially rectangular parallelepiped (flat) electrode assembly 200, the insulating sheet preferably covers the entire four faces other than the two faces on which the negative electrode tab group 220 and the positive electrode tab group 250 are formed, respectively.

[0066] Fig. 13 is a front view of the connection structure between the negative electrode tab group and the negative electrode current collector, and Fig. 14 is a cross-sectional view of the connection structure between the negative electrode tab group and the negative electrode current collector.

[0067] 13 and 14, the negative electrode current collector 410 electrically connects the negative electrode terminal 301 and the negative electrode tab group 220. The negative electrode current collector 410 in this embodiment is connected to the negative electrode terminal 301 between the electrode body 200 and the third member 150.

[0068] The negative electrode current collector 410 includes a first conductive member 430 and a second conductive member 440. The first conductive member 430 and the second conductive member 440 are joined at a joint 433. The first conductive member 430 and the second conductive member 440 are joined by, for example, laser welding.

[0069] The first conductive member 430 is joined to the negative electrode tab group 220 at a joining point 434. The joining point 434 can be formed by, for example, ultrasonic welding, resistance welding, laser welding, caulking, or the like. In the present embodiment, the first conductive member 430 and the negative electrode tab group 220 are joined by, for example, ultrasonic welding.

[0070] Second conductive member 440 is connected to negative electrode terminal 301 at joint 441. Joint 441 can be formed by, for example, ultrasonic welding, resistance welding, laser welding, crimping, or the like. In the present embodiment, negative electrode terminal 301 and second conductive member 440 are joined by, for example, providing a through hole in second conductive member 440, inserting negative electrode terminal 301 into the through hole, crimping negative electrode terminal 301 onto second conductive member 440, and then welding the crimped portion to second conductive member 440.

[0071] The first conductive member 430 has a first flat portion 431 and a second flat portion 432. The first flat portion 431 is connected to the second conductive member 440. The second flat portion 432 is connected to the negative electrode tab group 220. The second flat portion 432 is disposed along the third member 150.

[0072] A step portion 435 is provided between the first flat portion 431 and the second flat portion 432. The step portion 435 causes the first flat portion 431 and the second flat portion 432 to be positioned differently in the second direction (X direction) after the secondary battery 1 is assembled. This allows the first flat portion 431 and the second flat portion 432 to be arranged side by side in one direction. The step portion 435 extends along the third direction (Z direction).

[0073] A first insulating member 510 (resin member) is disposed between the negative electrode terminal 301 and the third member 150. A second insulating member 520 (resin member) is disposed between the third member 150 and the first conductive member 430 and the second conductive member 440. The first insulating member 510 and the second insulating member 520 may be an integrated part.

[0074] The negative electrode terminal 301 is attached to the third member 150 via the first insulating member 510. As a result, the negative electrode terminal 301 is attached to the third member 150 (third member) while being electrically insulated from the third member 150 (third member). The negative electrode terminal 301 is exposed to the outside of the third member 150 and is provided so as to reach the second conductive member 440 of the negative electrode current collector 410 provided on the inner surface side of the third member 150.

[0075] The procedure for assembling the components is as follows: first, the negative electrode terminal 301 and the second conductive member 440 are attached to the third member 150 together with the first insulating member 510 and the second insulating member 520. Next, the first conductive member 430 electrically connected to the electrode body 200 is attached to the second conductive member 440. At this time, the first conductive member 430 is placed on the first insulating member 510 so that a portion of the first conductive member 430 overlaps the second conductive member 440. Next, the first conductive member 430 and the second conductive member 440 are connected by welding at a joint 434.

[0076] However, the negative electrode terminal 301 may be electrically connected to the third member 150. Alternatively, the third member 150 may serve as the negative electrode terminal 301.

[0077] 13 and 14 show an example of the negative electrode current collector 410 made up of two parts (the first conductive member 430 and the second conductive member 440), but the negative electrode current collector 410 may be made up of a single part.

[0078] 13 and 14 show the connection structure on the negative electrode side, but the basic connection structure on the positive electrode side is similar to that on the negative electrode side. Specifically, an insulating member (not shown) is disposed between the positive electrode terminal 302 and the fourth member 160. The positive electrode current collector 420 is attached to the inner surface side of the fourth member 160 via a resin insulating member. The insulating member is provided so as to extend from the outer surface side to the inner surface side of the fourth member 160 via a through hole provided in the fourth member 160.

[0079] The positive electrode terminal 302 is attached to the fourth member 160 via an insulating member. As a result, the positive electrode terminal 302 is attached to the fourth member 160 (fourth member) in a state in which it is electrically insulated from the fourth member 160 (fourth member).

[0080] However, the positive electrode terminal 302 may be electrically connected to the fourth member 160. Alternatively, the fourth member 160 may serve as the positive electrode terminal 302.

[0081] FIG. 15 is a diagram showing a process of placing a first spacer 600 between the third member 150 and the electrode body 200. As shown in FIG.

[0082] 15, the negative electrode tab group 220 arranged from the electrode assembly 200 toward the third member 150 is curved from the center in the Y direction of the third member 150 toward the end, and then folded back toward the center. A first spacer 600 is provided to accommodate the curved portion of the negative electrode tab group 220. The first spacer 600 is disposed between the electrode assembly 200 and the third member 150 (sealing plate).

[0083] The first 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 by engaging portions 630a, 630b when they are slid along the Y direction from the end side toward the center of the third member 150. This fixes the first spacer 600 to the third member 150 via the first insulating member 510, increasing the stability of the position of the first spacer 600.

[0084] The secondary battery 1 according to this embodiment further includes a second spacer (not shown). The second spacer is disposed between the electrode body and the fourth member 160 (sealing plate). The second spacer may have the same structure as the first spacer 600. The first spacer 600 and the second spacer may have different shapes.

[0085] (Component configuration of case 100) Fig. 16 is a perspective view showing the component configuration of a case included in a secondary battery according to one embodiment, and Fig. 17 is a perspective view showing a state in which the components of the case are joined together.

[0086] As shown in FIGS. 16 and 17, case 100 according to this embodiment includes a bottom surface portion 121, an upper surface portion, a pair of first side surface portions 122, and a pair of second side surface portions 140.

[0087] Case 100 in this embodiment includes a first member 120, a second member 130, a third member 150, and a fourth member 160, which correspond to the respective parts of case 100 described above. First member 120 and second member 130 constitute case main body 110.

[0088] The first member 120 comprises a bottom surface portion 121 and a pair of first side surface portions 122. The first member 120 is formed by bending a single plate-shaped member.

[0089] The second member 130 constitutes the top surface portion. The third member 150 (sealing plate) constitutes one of the pair of second side surface portions 140. The fourth member 160 (sealing plate) constitutes the other of the pair of second side surface portions 140.

[0090] The bottom surface portion 121 has a longitudinal direction in the second direction (X direction) and a lateral direction in the first direction (Y direction).

[0091] The pair of first side surface portions 122 face each other in the first direction (Y direction). The pair of first side surface portions 122 have areas larger than the bottom surface portion 121 and the second member 130 (upper surface portion).

[0092] The second member 130 has a longitudinal direction in the second direction (X direction) and a lateral direction in the first direction (Y direction).

[0093] The second member 130 is joined to an end of the first side surface portion 122 of the first member 120. The second member 130 is joined to one 123 of the pair of first side surface portions by a joint 115a. The second member 130 is also joined to the other 124 of the pair of first side surface portions by a joint 115b.

[0094] The pair of second side surface portions 140 face each other in the second direction (X direction). The third member 150 (one of the pair of second side surface portions 140) is joined to the end portions of the first member 120 and the second member 130 at the end portions on the first side in the second direction (X direction). The third member 150 is joined to the first member 120 by a joint 170a. The third member 150 is joined to the second member 130 by a joint 170b.

[0095] The fourth member 160 (the other of the pair of second side surface portions 140) is joined to the end portions of the first member 120 and the second member 130 at the end portions on the second side opposite to the first side in the second direction (X direction). The fourth member 160 is joined to the first member 120 by a joint portion 171a. The fourth member 160 is joined to the second member 130 by a joint portion 171b.

[0096] FIG. 18 is a cross-sectional view showing a state in which the first member and the second member in the case are fitted together.

[0097] 18 , the pair of first side surface portions 122 of the first member 120 are partially bent at the end portions on the second member 130 side. The pair of first side surface portions 122 have inner surfaces 125 and first abutment surfaces 126. The second member 130 has an outer circumferential portion 131 and a second abutment surface 132.

[0098] The inner surface 125 is fitted with the outer circumferential portion 131. This positions the second member 130 relative to the first member 120 in the first direction (Y direction). The first abutment surface 126 and the second abutment surface 132 abut against each other, thereby positions the second member 130 relative to the first member 120 in the third direction (Z direction).

[0099] (Joining state between components of case 100) FIG. 19 is a cross-sectional view showing a state in which the third and fourth members are joined to the first and second members of the case.

[0100] As shown in FIG. 19, the case body 110 further has an outer peripheral surface portion 116, a first end surface 117, and a second end surface 118.

[0101] The outer peripheral surface portion 116 extends around an axis in the second direction (X direction). The outer peripheral surface portion 116 also extends along the second direction (X direction). Although the outer peripheral surface portion 116 extends approximately parallel to the second direction (X direction), it may be tilted from the second direction (X direction) due to processing errors during the manufacture of the case body 110, etc.

[0102] The first end surface 117 is located at the end of the first side in the second direction (X direction). The first end surface 117 extends in a direction intersecting the second direction (X direction). In this embodiment, the first end surface 117 extends in a direction substantially perpendicular to the second direction (X direction). Since the first end surface 117 extends in a direction substantially perpendicular to the second direction (X direction), the third member 150 is likely to come into contact with the first end surface 117.

[0103] The second end surface 118 is located at the end of the second side in the second direction (X direction). The second end surface 118 extends in a direction intersecting the second direction (X direction). In this embodiment, the second end surface 118 extends in a direction substantially perpendicular to the second direction (X direction). Since the second end surface 118 extends in a direction substantially perpendicular to the second direction (X direction), the fourth member 160 is likely to come into contact with it.

[0104] The third member 150 has a first covering portion 157. The first covering portion 157 covers at least a portion of the first end face 117 from the second direction (X direction). In the present embodiment, the first covering portion 157 covers the entire surface of the first end face 117 from the second direction (X direction). This makes it easy to stably position the third member 150 relative to the case body 110.

[0105] The fourth member 160 has a second covering portion 167. The second covering portion 167 covers at least a portion of the second end face 118 from the second direction (X direction). In the present embodiment, the second covering portion 167 covers the entire surface of the second end face 118 from the second direction (X direction). This makes it easy to stably position the fourth member 160 relative to the case body 110.

[0106] Bonding portions 170a and 170b are formed between the outer peripheral surface portion 116 and the first covering portion 157. Bonding portions 171a and 171b are formed between the outer peripheral surface portion 116 and the second covering portion 167. These bonding portions 170a, 170b, 171a, and 171b are formed by, for example, laser welding. Note that the bonding of the bonding portions 170a, 170b, 171a, and 171b is not limited to laser welding, and may be formed by other joining methods such as ultrasonic welding or resistance welding.

[0107] The joints 170a, 170b, 171a, and 171b are located on the outer peripheral surface 116 of the case body 110. Therefore, compared to a case where the entire third member and the fourth member are inserted into the inner peripheral surface of the case body and joints are formed between the outer peripheral surfaces of the third member and the fourth member and the inner peripheral surface of the case body, the joints 170a, 170b, 171a, and 171b can be located at locations farther away from the insulating members provided between the electrode terminal 300 and each of the pair of second side surface portions 140. This makes it possible to suppress the thermal effect on the insulating members during joining.

[0108] Although case 100 in this embodiment is configured from four members, namely, first member 120, second member 130, third member 150, and fourth member 160, the configuration is not limited to this. The case may be configured from five or six members in which bottom surface portion 121 and a pair of first side surface portions 122 of first member 120 are provided separately and joined together. Furthermore, the six faces that make up the rectangular outer surface of the case may be configured from seven or more members.

[0109] A method for manufacturing a secondary battery according to this embodiment will be described below. Fig. 20 is a flowchart showing a method for manufacturing a secondary battery according to one embodiment. Fig. 21 is a perspective view showing a state in which an electrode body is inserted into a first member of a case.

[0110] 20 and 21, in the method for manufacturing the secondary battery 1 according to the present embodiment, first, an electrode assembly 200 is prepared (step S1). A negative electrode current collector 410 is connected to the negative electrode tab group 220, and a positive electrode current collector 420 is connected to the positive electrode tab group 250.

[0111] Next, the first member 120 is prepared (step S2). The first member 120 is formed by bending a single plate-shaped member.

[0112] First member 120 is formed by bending a single plate-like member, and has a bottom surface portion 121, a pair of first side surface portions 122, an upper surface opening 127, and a pair of side surface openings 128 formed therein.

[0113] The pair of first side surface portions 122 rise from the bottom surface portion 121. The pair of first side surface portions 122 face each other in a first direction (Y direction). The top surface opening 127 faces the bottom surface portion 121. The pair of side surface openings 128 are located between both end portions of the pair of first side surface portions 122 in a second direction (X direction).

[0114] Next, the second member 130 is prepared (step S3). In this embodiment, the second member 130 is subjected to a bending process (not shown) in order to fit with the first member 120. This allows the second member 130 to fit into the top surface opening 127 and be joined.

[0115] Next, the negative electrode terminal 301 (first electrode terminal) is attached to the third member 150 (sealing plate) (step S4). Next, the positive electrode terminal 302 (second electrode terminal) is attached to the fourth member 160 (sealing plate) (step S5).

[0116] Next, the negative electrode terminal 301 (first electrode terminal) is electrically connected to the electrode body 200 (step S6). In this embodiment, the negative electrode tab group 220 connected to the negative electrode plate 210 of the electrode body 200 is electrically connected to the negative electrode terminal 301.

[0117] Next, the positive electrode terminal 302 (second electrode terminal) is electrically connected to the electrode body 200 (step S7). In this embodiment, the positive electrode tab group 250 connected to the positive electrode plate 240 of the electrode body 200 is electrically connected to the positive electrode terminal 302.

[0118] Next, the electrode body 200 is inserted between the pair of first side surface portions 122 of the first member 120 (step S8). The electrode body 200 is preferably inserted in the third direction (Z direction) from between the pair of first side surface portions 122 toward the bottom surface portion 121 (toward the direction DR1 in FIG. 21). Note that the electrode body 200 is not limited to being inserted from the third direction (Z direction), and may be inserted from the second direction (X direction) or obliquely on the XZ plane. Furthermore, it is preferable to insert the electrode body 200 between the pair of first side surface portions 122 of the first member 120 while the electrode body 200 is covered with a resin insulating sheet (electrode body holder). For example, it is preferable to cover the surface of the electrode body 200 that faces the bottom surface portion 121, the surface that faces one of the first side surface portions 122, and the surface that faces the other first side surface portion 122 with an insulating sheet after insertion into the first member 120. Furthermore, the surface of the electrode body 200 that faces the upper surface opening 127 can be covered with an insulating sheet.

[0119] Next, after inserting the electrode body 200 between the pair of first side surface portions 122, the second member 130 is joined to the end of each of the pair of first side surface portions 122, and the top surface opening 127 is closed (step S9). Each of the pair of first side surface portions 122 and the second member 130 are welded by, for example, a laser. Note that the joining of each of the pair of first side surface portions 122 and the second member 130 may be performed by ultrasonic welding, resistance welding, or the like.

[0120] The first spacer 600 and the second spacer are disposed between the electrode body 200 and the third and fourth members 150 and 160 after the electrode tabs are bent at any timing in the above-described process.

[0121] 22 is a perspective view illustrating a method for joining a first member, a second member, and a third member of a case included in a secondary battery according to one embodiment, and illustrates joining on the negative electrode side.

[0122] Next, as shown in FIGS. 20 and 22, before the step of closing the pair of side openings 128, the third member 150 and the fourth member 160 are temporarily joined to the first member 120 and the second member 130 (step S10).

[0123] The temporary joints are formed by joining the first and second members 120 and 130 at points among the joining locations to temporarily fasten the third and fourth members 150 and 160 together. The temporary joints in this embodiment are formed by joining the first and second members 120 and 130 at points on each of the four sides at the end of each member. The temporary joints may be, for example, relatively short (for example, less than 1 cm) linear joints. Furthermore, temporary joints are not necessarily required.

[0124] 20 to 22, after the step of closing the top opening 127, the pair of side openings 128 are closed (step S11). Specifically, a third member 150 and a fourth member 160 are joined to the ends of the first member 120 and the second member 130, respectively, at both ends in the second direction (X direction), thereby closing the pair of side openings 128.

[0125] The third member 150 is brought into contact with the first end face 117 so as to cover at least a portion of the first end face 117 from the second direction (X direction), and a joining process is performed from the outer periphery around the axis in the second direction (X direction) to join the third member 150 and the outer periphery surface portion 116 of the case body 110.

[0126] Similar to the joining of the third member 150, the fourth member 160 is brought into contact with the second end face 118 so as to cover at least a portion of the second end face 118 from the second direction (X direction), and a joining process is performed from the outer periphery around the axis in the second direction (X direction) to join the fourth member 160 and the outer periphery surface portion 116 of the case body 110.

[0127] In the step of closing the pair of side openings 128, it is preferable that at least a part of the joining of the third member 150 and the fourth member 160 is performed simultaneously. In the present embodiment, the joining of the third member 150 and the joining of the fourth member 160 are performed so that the start and end of the joining are approximately the same.

[0128] Note that the joining steps of the third member 150 and the fourth member 160 may partially overlap. Furthermore, these joining steps may start simultaneously but not necessarily end simultaneously, or may not start simultaneously but end simultaneously. When these joining steps partially overlap, it does not matter which of the joining steps of the third member 150 and the joining step of the fourth member 160 is performed first.

[0129] Fig. 23 is a side view showing the state immediately after starting to join the first and second members of the case with the third member. Fig. 24 is a side view showing the state in which the short side portions of the first and second members of the case and the third member are joined while being rotated. Fig. 25 is a side view showing the state in which the long side portions of the first and second members of the case and the third member are joined while being rotated. Figs. 23 to 25 only show the first member 120 and the second member 130.

[0130] As shown in FIGS. 22 to 25 , during at least part of the process of closing the pair of side openings 128, the joining process (e.g., laser welding) is performed while rotating the first member 120 and the second member 130 (rotating in the r1 direction in FIG. 22 ) in a state where the joined first member 120 and the second member 130 are held rotatably around an axis in the second direction (X direction). In this embodiment, during all of the process of closing the pair of side openings 128, the first member 120 and the second member 130 are rotated and welding is performed using the laser 3. During joining, the case body 110 is continuously rotated. The focal length of the laser 3 is adjusted in accordance with the continuous rotation of the case body 110 by moving the joining device 2. Note that the joining process may be performed while changing the rotation speed of the first member 120 and the second member 130. Furthermore, after the joining process, the first member 120 and the second member 130 may be rotated, and then the joining process may be performed again in a state where the first member 120 and the second member 130 are stopped.

[0131] The first member 120 is pressed by a manufacturing device (not shown) until it is deformed along the first direction (Y direction). As a result, the electrode body 200 is sandwiched between the first member 120. At this time, it is preferable to elastically deform the first member 120. An insulating sheet may be disposed between the first member 120 and the electrode body 200.

[0132] The six sides that make up the outer surface of the rectangular case 100 are closed by joining the components of the case 100 as described above. After the above steps are completed, electrolyte is poured into the inside of the case 100 through the pouring hole, and secondary battery 1 is completed.

[0133] The order of the steps in the method for manufacturing the secondary battery 1 is not limited unless the order of the steps is clearly indicated.

[0134] A secondary battery according to a modified example of the embodiment will be described below. The secondary battery according to this modified example has a case structure different from that of secondary battery 1 according to the embodiment of the present technology, and therefore, description of the configuration similar to that of secondary battery 1 according to the embodiment of the present technology will not be repeated.

[0135] FIG. 26 is a cross-sectional view showing a fitted state between a first member and a second member in a case according to a first modified example of an embodiment.

[0136] As shown in Fig. 26, the case 100A included in the secondary battery according to the first modification includes a first member 120A and a second member 130A. The first member 120A has a pair of first side surface portions 122A. The pair of first side surface portions 122A have inner side surfaces 125A and first contact surfaces 126A. The second member 130A is partially bent at an end portion in the first direction (Y direction). The second member 130A has a vertical wall portion 133A and a second contact surface 132A.

[0137] The inner surface 125A fits into the vertical wall portion 133A. This positions the second member 130A relative to the first member 120A in the first direction (Y direction). The first abutment surface 126A and the second abutment surface 132A abut against each other, thereby positioning the second member 130A relative to the first member 120A in the third direction (Z direction). The first member 120A and the second member 130A are joined at joints 115c and 115d.

[0138] FIG. 27 is a cross-sectional view showing a fitted state between a first member and a second member in a case according to a second modified example of an embodiment.

[0139] 27, the case 100B included in the secondary battery according to the second modification includes a first member 120B and a second member 130B. The first member 120B has a pair of first side surface portions 122B. The pair of first side surface portions 122B have inner surfaces 125B. The second member 130B has an outer circumferential portion 131B.

[0140] The inner surface 125B is fitted with the outer circumferential portion 131B. This positions the second member 130B relative to the first member 120B in the first direction (Y direction). The first member 120B and the second member 130B are joined at joints 115e and 115f.

[0141] 28 is a perspective view illustrating a joined state between a first member and a third member of a case included in a secondary battery according to a third modified example of an embodiment. In FIG. 28, the joining between the first member and the third member is illustrated.

[0142] 28, a secondary battery 1C according to this modification includes a case 100C. The case 100C includes a first member 120C, a second member, and a third member 150C.

[0143] The first member 120C and the second member have an inner circumferential surface portion 119C. The inner circumferential surface portion 119C extends around an axis in the second direction (X direction).

[0144] The third member 150C has a first portion 151C and a second portion 152C.

[0145] The first portion 151C enters the inside of the case 100C from the first side ends of the first member 120C and the second member. The first portion 151C faces the first member 120C and the second member from the inside of the case 100C. In the present embodiment, the first portion 151C faces the inner circumferential surface portion 119C of the first member 120C and the second member from the inside of the case 100C.

[0146] The second portion 152C abuts against the first side end of the first member 120C and the second member from the second direction (X direction).

[0147] A joint 170C is formed between the third member 150C and the outer circumferential surface portion 116C. The joint 170C is a welded portion formed by laser welding. In the step of closing the pair of side openings, the third member 150C and the outer circumferential surface portion 116C are welded together by irradiating them with a laser from the outer circumferential side around the axis in the second direction (X direction) (direction DR2 in FIG. 28).

[0148] Since first portion 151C is disposed to fit into inner circumferential surface portion 119C, the position of third member 150C is stabilized relative to first member 120C and second member 120C, thereby enabling stable laser welding.

[0149] The third member 150C has a protrusion 153C on its outer surface. The protrusion 153C is provided adjacent to the second portion 152C. This prevents the periphery of the second portion 152C of the third member 150C from excessively melting during laser welding, thereby preventing welding sagging and the like from occurring on the outer surface side.

[0150] Although FIG. 28 shows the configuration of the negative electrode side, the positive electrode side may have a similar structure to the negative electrode side. The fourth member may also have a similar configuration to the third member 150C. Specifically, the fourth member has a third portion and a fourth portion. The third portion enters the inside of the case 100C from the second-side ends of the first member 120C and the second member. The third portion faces the first member 120C and the second member from the inside of the case 100C. The fourth portion abuts the second-side ends of the first member 120C and the second member from the second direction (X direction). A joint is formed between the fourth member and the outer peripheral surface portion 116C. The joint is a weld formed by laser welding. The fourth member and the outer peripheral surface portion 116C are welded.

[0151] When the joint 170C is formed by laser welding, even if the laser penetrates into the inner surface portion 119C of the first member 120C and the second member from the outer periphery around the axis in the second direction (X direction) (in FIG. 28, the DR2 direction), the laser can be received by the first portion 151C and the third portion, thereby preventing the laser from slipping out during laser welding.

[0152] In a secondary battery 1 and a manufacturing method thereof according to an embodiment of the present technology, the case 100 is configured to include a first member 120 and a second member 130 divided about an axis in the second direction (X direction). This allows the electrode assembly 200 to be inserted into the case 100 between a pair of first side surface portions 122 of the first member 120 and into an inner region of the first member 120. This reduces the area of ​​the electrode assembly 200 surrounded by the case 100 around the axis in the insertion direction of the electrode assembly 200, compared to a case in which the electrode assembly is inserted through openings located at both ends of the rectangular cylindrical case and the electrode assembly is surrounded by the case around its entire circumference around the axis in the insertion direction of the electrode assembly 200. This makes it easier to insert the electrode assembly 200 into the case 100. This allows for stable manufacturing of a highly reliable secondary battery 1. For example, unintended deformation or damage to the negative electrode tab group 220 or the positive electrode tab group 250 can be suppressed, or unintended deformation or damage to the electrode assembly 200 can be effectively suppressed.

[0153] The structure of the case 100 included in the secondary battery 1 according to this embodiment is particularly effective when the width of the electrode body 200 in the second direction (X direction) is large (20 cm or more, more preferably 25 cm).

[0154] In a secondary battery 1 and a manufacturing method thereof according to one embodiment of the present technology, by providing a negative electrode tab group 220 (first electrode tab group) and a positive electrode tab group 250 (second electrode tab group) of the electrode body 200, the energy density of the electrode body 200 can be improved, and therefore a secondary battery 1 with excellent output characteristics can be constructed.

[0155] In the secondary battery 1 and its manufacturing method according to one embodiment of the present technology, by providing a negative electrode terminal 301 (first electrode terminal) and a positive electrode terminal 302 (second electrode terminal) on the third member 150 and the fourth member 160, respectively, the secondary battery 1 can be made low-profile when the secondary battery 1 is placed on the bottom surface 121 of the case 100 as the placement surface.

[0156] In a secondary battery 1 according to one embodiment of the present technology, the negative terminal 301 is attached to the third member 150 while being electrically insulated from the third member 150, and the positive terminal 302 is attached to the fourth member 160 while being electrically insulated from the fourth member 160, thereby reducing the number of locations in the secondary battery 1 that require insulation.

[0157] In the secondary battery 1 according to an embodiment of the present technology, the first spacer 600 and the second spacer can be used to prevent the electrode body 200 from being too close to the third member 150 and the fourth member 160. This allows for a configuration in which the electrode body 200 is not positioned directly below the joining positions of the first member 120 and the second member 130 and the third member 150 and the fourth member 160, and therefore prevents the electrode body 200 from being damaged even if a laser for joining enters the interior of the case 100 between these members.

[0158] In a modified example of secondary battery 1 according to the embodiment of the present technology, third member 150C is provided with first portion 151C facing inner circumferential surface portion 119C of first member 120C and second member, and third member 150C is provided with second portion 152C abutting against end surfaces of first member 120C and second member, so that when these are joined, third member 150C can be stably abutted against first member 120C and second member. This makes it possible to stably form joints between first member 120C and second member and third member 150C.

[0159] In the manufacturing method of the secondary battery 1 according to one embodiment of the present technology, the joints 170a, 170b, 171a, 171b can be formed while rotating the first member 120 and the second member 130. Therefore, compared to a configuration in which the first member 120 and the second member 130 are stationary and the joining device moves around the first member 120 and the second member 130, the joining device 2 can be made smaller and the secondary battery 1 can be manufactured more efficiently.

[0160] In a manufacturing method of a secondary battery 1 according to one embodiment of the present technology, the first member 120 is held by a manufacturing device to an extent that the first member 120 can clamp the electrode body 200. This prevents the electrode body 200 from moving inside the first member 120 and the second member 130 when the first member 120 and the second member 130 are rotated to join them, thereby suppressing damage to the electrode body 200.

[0161] In a manufacturing method of a secondary battery 1 according to one embodiment of the present technology, by temporarily joining the third member 150 and the fourth member 160 to the first member 120 and the second member 130 before the step of closing the pair of side openings 128, it is possible to suppress misalignment of the third member 150 and the fourth member 160 relative to the first member 120 and the second member 130 when rotating the first member 120 and the second member 130 to join them.

[0162] In a manufacturing method of a secondary battery 1 according to one embodiment of the present technology, the third member 150 and the fourth member 160 are simultaneously joined to the first member 120 and the second member 130, thereby enabling the secondary battery 1 to be manufactured efficiently.

[0163] In the manufacturing method of the secondary battery 1 according to the embodiment of the present technology, by inserting the electrode body 200 from the top surface opening 127, the electrode body 200 is surrounded only by the pair of first side surface portions 122 of the first member 120 during insertion. Therefore, the electrode body 200 can be inserted into the internal region of the first member 120 with a smaller surrounded area than when the electrode body 200 is inserted from a pair of side surface openings 128 surrounded by the bottom surface portion 121 and the pair of first side surface portions 122 of the first member 120. This makes it possible to stably manufacture a highly reliable secondary battery 1. For example, unintended deformation or damage to the negative electrode tab group 220 or the positive electrode tab group 250 can be suppressed, or unintended deformation or damage to the electrode body 200 can be effectively suppressed.

[0164] 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]

[0165] 1, 1C secondary battery, 2 bonding device, 3 laser, 100, 100A, 100B, 100C case, 110 case body, 113 first opening, 114 second opening, 115a, 115b, 115c, 115d, 115e, 115f, 170C, 170a, 170b, 171a, 171b bonding portion, 116, 116C outer peripheral surface portion, 117 first end surface, 118 second end surface, 119C inner peripheral surface portion, 120, 120A, 120B, 120C first member, 121 bottom surface portion, 122, 122A, 122B first side surface portion, 123 one of a pair of first side surface portions, 124 the other of the pair of first side surface portions, 125, 125A, 125B Inner surface, 126, 126A First contact surface, 127 Top opening, 128 Pair of side openings, 130, 130A, 130B Second member (top surface portion), 131, 131B Outer periphery, 132, 132A Second contact surface, 133A Vertical wall portion, 140 Second side portion, 150, 150C Third member (sealing plate), 151C First portion, 152C Second portion, 153C Convex portion, 154, 164 Liquid inlet, 155, 165 Gas release valve, 157 First covering portion, 160 Fourth member (sealing plate), 167 Second covering portion, 200, 201, 202 Electrode body, 210 Negative electrode plate, 210S Negative electrode base plate, 211 Negative electrode core, 212 Negative electrode active material layer, 220 Negative electrode tab group, 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 positive electrode tab group, 260 positive electrode tab, 300 electrode terminal, 301 negative electrode terminal, 302 positive electrode terminal, 400 current collector, 410 negative electrode current collector, 420 positive electrode current collector, 430 first conductive member, 431 first flat portion, 432 second flat portion, 433, 434, 441, 454 joint portion, 435 step portion, 440 second conductive member, 510 first insulating member, 520 second insulating member, 600 first spacer, 610 first part, 620 second part, 630a, 630b engaging portion.

Claims

1. An electrode body; a rectangular case that includes a bottom surface, an upper surface that faces the bottom surface, a pair of first side surfaces that face each other in a first direction, and a pair of second side surfaces that face each other in a second direction that is perpendicular to the first direction, and that houses the electrode body; a first electrode terminal and a second electrode terminal electrically connected to the electrode body; The case is a first member constituting the bottom surface portion and the pair of first side surface portions; a second member that forms the upper surface portion and is joined to an end of the first side surface portion of the first member; a third member that constitutes one of the pair of second side surface portions and is joined to an end portion of each of the first member and the second member at an end portion on a first side in the second direction; a fourth member that configures the other of the pair of second side surface portions and is joined to the end portions of the first member and the second member at end portions of a second side opposite to the first side in the second direction, the third member and the fourth member each have a rectangular shape, when viewed from the second direction, in which the first direction is a short side direction and a third direction perpendicular to the first direction and the second direction is a long side direction; the third member is joined to the first member and the second member at an end portion on the first side by a weld portion that is continuously formed across the bottom surface portion, the pair of first side surface portions, and the top surface portion; the fourth member is joined to the first member and the second member at an end portion on the second side by a weld portion that is continuously formed across the bottom surface portion, the pair of first side surface portions, and the top surface portion; The electrode body is a main body having 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 electrodes and located at an end of the main body portion on the first side; a second electrode tab group electrically connected to the second electrodes and located at an end of the second side relative to the main body portion; the first electrode terminal is provided on the third member, the second electrode terminal is provided on the fourth member, the first electrode tab group is electrically connected to the first electrode terminals; The second electrode tab group is electrically connected to the second electrode terminals.

2. the first electrode terminal is attached to the third member in a state of being electrically insulated from the third member; The secondary battery according to claim 1 , wherein the second electrode terminal is attached to the fourth member in a state in which the second electrode terminal is electrically insulated from the fourth member.

3. a first spacer located between the electrode body and the third member; The secondary battery according to claim 1 or 2, further comprising a second spacer between the electrode body and the fourth member.

4. The third member is a first portion that is positioned inside the case further than the first side ends of the first member and the second member and faces the first member and the second member from inside the case; 3. The secondary battery according to claim 1, further comprising: a second portion abutting the first member and the second member at the end portions on the first side from the second direction.

5. A method for manufacturing the secondary battery according to claim 1, preparing the electrode body, the first member having a top surface opening facing the bottom surface portion, and a pair of side surface openings located between both ends of each of the pair of first side surface portions in a second direction perpendicular to the first direction, the second member, the third member, and the fourth member; attaching a first electrode terminal to the third member; attaching a second electrode terminal to the fourth member; a step of electrically connecting the first electrode tab group and the first electrode terminals; a step of electrically connecting the second electrode tab group and the second electrode terminals; inserting the electrode body between the pair of first side surface portions of the first member; a step of inserting the electrode body between the pair of first side surface portions, and then joining the second member to each end of the pair of first side surface portions, and closing the top surface opening; after the step of closing the top surface opening, a step of joining the third member to the first member and the second member to close one of the pair of side surface openings, and joining the fourth member to the first member and the second member to close the other of the pair of side surface openings, thereby closing the pair of side surface openings.

6. 6. The method for manufacturing a secondary battery according to claim 5, wherein at least a part of the step of closing the pair of side openings includes rotating the first member and the second member while holding the first member and the second member rotatably around an axis in the second direction.

7. 7. The method for manufacturing a secondary battery according to claim 6, wherein at least a part of the step of closing the pair of side openings includes pressing the first member along the first direction to deform the first member and sandwiching the electrode body between the first members.

8. 8. The method for manufacturing a secondary battery according to claim 6, wherein the step of closing the pair of side openings includes temporarily joining the third member and the fourth member to the first member and the second member.

9. 7. The method for manufacturing a secondary battery according to claim 5, wherein in the step of closing the pair of side openings, at least a part of joining the third member and a part of joining the fourth member are performed simultaneously.

10. 7. The method for manufacturing a secondary battery according to claim 5, wherein the step of inserting the electrode body includes inserting the electrode body toward the bottom surface portion.

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