Secondary battery

Abstract

To provide a secondary battery with high capacity and high reliability.SOLUTION: A secondary battery comprises: an electrode body containing a first electrode and a second electrode having a polarity that is different from the polarity of the first electrode; and a case that houses the electrode body. The case includes: a case main body that has a first opening part positioned at an end part on a first side in a first direction and a second opening part positioned at an end part on a second side on the side opposite to the first side in the first direction; a first end-sealing plate that seals the first opening part; and a second sealing plate that seals the second opening part. The case main body includes: a pair of first walls opposite to each other in a second direction orthogonal to the first direction; and a pair of second walls orthogonal to each other in a third direction orthogonal to each other in the first and second directions. An area of the pair of first walls is larger than an area of the pair of second walls. A gas exhaust valve that breaks when a pressure in the case becomes a predetermined value or larger at one of the pair of second walls, and a bonding part extended in the first direction is provided at the other of the pair of second walls.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present technology relates to a secondary battery. [Background technology]

[0002] Japanese Patent Laid-Open Publication No. 2001-143664 (Patent Document 1) discloses that a thin-walled portion is formed on any side surface of a rectangular case, excluding the terminal surface and the bottom surface, to serve as a safety valve. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2001-143664 A Summary of the Invention [Problem to be solved by the invention]

[0004] As the capacity of batteries increases, the size of secondary batteries is also increasing. From the viewpoint of reliability of large secondary batteries, there is room for further improvement in the battery described in Patent Document 1. An object of the present technology is to provide a secondary battery with high capacity and reliability. [Means for solving the problem]

[0005] The present technology provides the following secondary battery.

[0006] [1] A secondary battery comprising: an electrode body including a first electrode and a second electrode having a polarity different from that of the first electrode; and a case housing the electrode body, wherein the case includes a case body having a first opening located at an end of a first side in a first direction and a second opening located at an end of a second side opposite the first side in the first direction, a first sealing plate sealing the first opening, and a second sealing plate sealing the second opening, wherein the case body includes a pair of first walls facing each other in a second direction perpendicular to the first direction, and a pair of second walls perpendicular to each other in a third direction perpendicular to each other in the first direction and the second direction, wherein an area of ​​the pair of first walls is larger than an area of ​​the pair of second walls, one of the pair of second walls is provided with a gas release valve that ruptures when pressure inside the case reaches or exceeds a predetermined value, and the other of the pair of second walls is provided with a joint extending in the first direction.

[0007] [2] The secondary battery according to [1], wherein the gas release valve includes a thin portion or a groove portion formed in one of the pair of second walls.

[0008] [3] The secondary battery described in [1] or [2], wherein the electrode body includes a main body portion, a first electrode tab electrically connected to the first electrode and located on a first side relative to the main body portion, and a second electrode tab electrically connected to the second electrode and located on a second side relative to the main body portion, the first electrode tab being electrically connected to a first electrode terminal provided on the first sealing plate, and the second electrode tab being electrically connected to a second electrode terminal provided on the second sealing plate.

[0009] [4] The secondary battery described in [1] or [2], wherein the electrode body includes a main body, a first electrode tab electrically connected to the first electrode and located on a first side relative to the main body, and a second electrode tab electrically connected to the second electrode and located on a second side relative to the main body, wherein at least a part of the gas release valve is disposed in a first end region closer to the first opening than the main body of the electrode body in the first direction, and at least a part of the gas release valve is disposed in a second end region closer to the second opening than the main body of the electrode body in the first direction.

[0010] [5] The secondary battery according to any one of [1] to [4], wherein the electrode body includes a first electrode body and a second electrode body, each of the first electrode body and the second electrode body is a wound electrode body, the first electrode body and the second electrode body are arranged adjacent to each other, the first electrode body includes a first curved surface facing one of a pair of second walls, the first curved surface having a first vertex closest to one of the pair of second walls, the second electrode body includes a second curved surface facing one of the pair of second walls, the second curved surface having a second vertex closest to the one of the pair of second walls, and at least a part of the gas release valve is arranged in a region located between the first vertex and the second vertex in the second direction.

[0011] [6] The secondary battery of any one of [1] to [5], further comprising an insulating sheet covering at least a portion of an outer periphery of the electrode body, the insulating sheet including a first end edge and a second end edge extending in a first direction, the first end edge and the second end edge being positioned opposite one of a pair of second walls, and a region where the insulating sheet is double-layered is provided between the first end edge and the second end edge.

[0012] [7] The secondary battery according to any one of [1] to [5], wherein the gas release valve is arranged in a plurality of regions separated from each other in one of the pair of second walls.

[0013] [8] A secondary battery described in any one of [1] to [7], wherein a thin-walled region in which the thickness of the case body is relatively small is formed in one of the pair of second walls, and the gas release valve is positioned inside the thin-walled region.

[0014] [9] The secondary battery according to any one of [1] to [8], wherein the joint is disposed at a position shifted toward either end from the center of the other of the pair of second walls in the second direction. Effect of the Invention

[0015] According to the present technology, by providing a gas release valve on one of a pair of opposing second walls and providing a joint portion extending in a first direction on the other, the gas release valve and the joint portion are spaced apart on different sides of the case body, making it possible to stabilize the operating pressure of the gas release valve, and thus to provide a high-capacity and highly reliable secondary battery. [Brief description of the drawings]

[0016] [Figure 1] 1 is a front view showing a configuration of a secondary battery according to an embodiment of the present technology; [Diagram 2] 2 is a diagram showing the secondary battery shown in FIG. 1 as viewed from the direction of arrow II. [Diagram 3] 3 is a diagram showing the secondary battery shown in FIG. 1 as viewed from the direction of arrow III. [Figure 4] 4 is a diagram showing the secondary battery shown in FIG. 1 as viewed from the direction of arrow IV. [Diagram 5] 2 is a diagram showing the secondary battery shown in FIG. 1 as viewed from the direction of arrow V. FIG. [Figure 6] 2 is a front cross-sectional view of the secondary battery shown in FIG. [Figure 7] FIG. 2 is a front view showing a negative electrode original plate before the negative electrode plate is formed. [Figure 8] 8 is a cross-sectional view taken along the line VIII-VIII of the negative electrode original plate shown in FIG. 7. [Figure 9] FIG. 2 is a front view showing a negative electrode plate formed from the negative electrode original plate. [Figure 10] FIG. 2 is a front view showing a positive electrode original plate before the positive electrode plate is formed. [Figure 11] 11 is a cross-sectional view taken along the line XI-XI of the positive electrode plate shown in FIG. [Figure 12] FIG. 2 is a front view showing a positive electrode plate formed from a positive electrode original plate. [Figure 13] FIG. 2 is a diagram showing an electrode assembly and a current collector taken out from a secondary battery. [Figure 14] FIG. 4 is a front view of a connection structure between a negative electrode tab group and a negative electrode current collector. [Figure 15] FIG. 4 is a cross-sectional view of a connection structure between a negative electrode tab group and a negative electrode current collector. [Figure 16] 11A to 11C are diagrams showing a process of inserting the electrode body into the case body. [Figure 17] 11A and 11B are diagrams showing a step of arranging a spacer between the sealing plate and the electrode body. [Figure 18] 4A and 4B are diagrams showing plate-shaped members constituting a case main body. [Figure 19] 19 is a diagram showing a state in which the plate-like member shown in FIG. 18 is folded. FIG. [Figure 20] 5A and 5B are diagrams showing an example of the arrangement of an electrode body and an insulating sheet inside a case body. [Figure 21] FIG. [Figure 22] FIG. 2 is a front view showing an electrode body and an insulating sheet. [Figure 23] 13A and 13B are diagrams showing modified examples of the arrangement of the electrode assembly and separators inside the case body. [Figure 24] FIG. 2 shows an upper portion of a plurality of wound electrode bodies. [Diagram 25] FIG. 1 is a diagram showing the arrangement of gas exhaust valves. [Figure 26] FIG. 2 is a diagram showing the arrangement of the gas exhaust valve. [Figure 27] FIG. 3 is a diagram showing the arrangement of the gas exhaust valve. [Figure 28] FIG. 4 is a diagram showing the arrangement of the gas exhaust valve. [Figure 29] FIG. 5 is a diagram showing the arrangement of the gas exhaust valve. [Diagram 30] FIG. 6 shows the arrangement of the gas exhaust valve. [Diagram 31] FIG. 7 is a diagram showing the arrangement of the gas exhaust valve. [Diagram 32] FIG. 8 shows the arrangement of the gas exhaust valve. [Diagram 33] FIG. 9 shows the arrangement of the gas exhaust valve. [Diagram 34] This is a cross-sectional view taken along line XXXIV-XXXIV in Figure 33. [Diagram 35] 4 is an enlarged cross-sectional view showing an example of a groove portion that constitutes a gas release valve. FIG. [Diagram 36] FIG. 4 is a diagram for explaining the arrangement of a gas release valve in a first direction. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, embodiments of the present technology will be described. Note that the same or corresponding parts are denoted by the same reference characters, and description thereof will not be repeated.

[0018] In the embodiments described below, when referring to the number, amount, etc., the scope of the present technology is not necessarily limited to the number, amount, etc., unless otherwise specified. In addition, in the following embodiments, each component is not necessarily essential to the present technology, unless otherwise specified. In addition, the present technology is not necessarily limited to those that achieve all of the effects and advantages mentioned in the present embodiment.

[0019] In this specification, the words "comprise", "include" and "have" are open-ended, i.e., when a certain configuration is included, other configurations may or may not be included.

[0020] Furthermore, when geometric terms and terms expressing positional and directional relationships, such as "parallel," "orthogonal," "45° diagonal," "coaxial," and "along" are used in this specification, these terms allow for manufacturing errors and slight variations. When terms expressing relative positional relationships, such as "upper side" and "lower side," are used in this specification, these terms are used to indicate relative positional relationships in one state, and the relative positional relationships can be inverted or rotated to any angle depending on the installation direction of each mechanism (for example, by turning the entire mechanism upside down).

[0021] 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, sodium ion batteries, and solid electrolyte secondary batteries. In this specification, the term "electrode" may collectively refer to a positive electrode and a negative electrode.

[0022] In the drawings, the direction along the winding axis of the electrode body of the secondary battery is the X direction as a first direction, the Y direction is the short side direction of the electrode body that is perpendicular to the first direction and seen from the first direction as a second direction, and the Z direction is the long side direction of the electrode body that is perpendicular to the first direction and seen from the first direction as a third direction. In addition, in order to make the invention easier to understand, the dimensions of each component in the drawings are sometimes shown differently from the actual dimensions.

[0023] In this specification, the first direction (X direction) may be referred to as the "width direction" of the secondary battery or the case body, the second direction (Y direction) may be referred to as the "thickness direction" of the secondary battery or the case body, and the third direction (Z direction) may be referred to as the "height direction" of the secondary battery or the case body.

[0024] (Overall battery configuration) Fig. 1 is a front view of a secondary battery 1 according to the present embodiment. Figs. 2 to 5 are views of the secondary battery 1 shown in Fig. 1 as viewed from the directions of arrows II, III, IV, and V, respectively. Fig. 6 is a front cross-sectional view of the secondary battery 1 shown in Fig. 1.

[0025] The secondary battery 1 can be mounted in an electric vehicle (BEV: Battery Electric Vehicle), a plug-in hybrid electric vehicle (PHEV: Plug-in Hybrid Electric Vehicle), a hybrid electric vehicle (HEV: Hybrid Electric Vehicle), etc. However, the use of the secondary battery 1 is not limited to being mounted on a vehicle.

[0026] 1 to 6, the secondary battery 1 includes a case 100, an electrode assembly 200, an electrode terminal 300, and a current collector 400. The case 100 includes a case body 110, a first sealing plate 120, and a second sealing plate .

[0027] When configuring an assembled battery including the secondary batteries 1, multiple secondary batteries 1 are stacked in their thickness direction. The stacked secondary batteries 1 may be constrained in the stacking direction (Y direction) by a restraining member to form a battery module, or the assembled battery may be directly supported on the side surface of a battery pack case without using a restraining member.

[0028] 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.

[0029] As shown in Fig. 1 and Fig. 2, a first sealing plate 120 and a second sealing plate 130 are provided at both ends of the case body. The case body 110 can be formed into a square tube shape, for example, by abutting the edges of bent plate-like members (joint 115 shown in Fig. 2) and joining them together (for example, by laser welding). The corners of the "square tube" may have an R shape. The joint 115 in this embodiment extends in a first direction (X direction) on the outer circumferential surface of the case body 110.

[0030] In this embodiment, the case body 110 is formed to be 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 a relatively large (high capacity) secondary battery 1 to be configured. 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 a relatively low height (low height) secondary battery 1 to be configured, improving the mountability in a vehicle, for example.

[0031] The case body 110 includes a pair of first side surface portions 111 (first walls) and a pair of second side surface portions 112 (second walls). The pair of first side surface portions 111 constitute a part of the side surface of the case 100. The pair of second side surface portions 112 constitute a top surface portion 112A and a bottom surface portion 112B of the case 100. The pair of first side surface portions 111 and the pair of second side surface portions 112 are provided so as to intersect with each other. The pair of first side surface portions 111 and the pair of second side surface portions 112 are connected at their respective ends. Each of the pair of first side surface portions 111 has a larger area than each of the pair of second side surface portions 112.

[0032] 3, a first opening 113 is provided at an end of a first side in a first direction (X direction) of case body 110. First opening 113 is sealed by a first sealing plate 120. First opening 113 and first sealing plate 120 have a substantially rectangular shape with a short side direction in the Y direction and a long side direction in the Z direction.

[0033] A negative electrode terminal 301 (first electrode terminal) and a liquid injection hole 121 are provided on the first sealing plate 120. The positions of the negative electrode terminal 301 and the liquid injection hole 121 can be changed as appropriate. The first sealing plate 120 can be joined to the case body 110 by, for example, laser welding.

[0034] 4, a second opening 114 is provided at an end of a second side opposite to the first side in the first direction (X direction) of case body 110. Second opening 114 is sealed by a second sealing plate 130. Second opening 114 and second sealing plate 130 have a substantially rectangular shape with a short side direction in the Y direction and a long side direction in the Z direction.

[0035] A positive electrode terminal 302 (second electrode terminal) and a liquid injection hole 131 are provided on the second sealing plate 130. The positions of the positive electrode terminal 302 and the liquid injection hole 131 can be changed as appropriate. The second sealing plate 130 can be joined to the case body 110 by, for example, laser welding.

[0036] The first sealing plate 120 and the second sealing plate 130 are made of metal. Specifically, the first sealing plate 120 and the second sealing plate 130 are made of aluminum, an aluminum alloy, iron, an iron alloy, or the like.

[0037] In one example, the thickness of each of the first sealing plate 120 and the second sealing plate 130 is greater than the thickness of the case body 110 (plate thickness).

[0038] The negative electrode terminal 301 is electrically connected to the negative electrode of the electrode body 200. The negative electrode terminal 301 is attached to the first sealing plate 120, that is, the case 100.

[0039] The positive electrode terminal 302 is electrically connected to the positive electrode of the electrode body 200. The positive electrode terminal 302 is attached to the second sealing plate 130, i.e., the case 100.

[0040] The negative 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 terminal 301 may be provided with a portion or layer made of aluminum or an aluminum alloy.

[0041] 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.

[0042] The liquid inlet holes 121 and 131 are sealed with a sealing member (not shown) which may be, for example, a blind rivet or other metal member.

[0043] 5, a gas exhaust valve 150 is provided on the upper surface 112A of the case 100. The gas exhaust valve 150 is formed so as to extend in the X direction. The gas exhaust valve 150 is a thin-walled portion formed on the upper surface 112A of the case 100. The gas exhaust valve 150 breaks when the pressure inside the case 100 reaches or exceeds a predetermined value, and exhausts gas inside the case 100 to the outside.

[0044] The electrode body 200 is a flat-shaped electrode body having a positive electrode plate and a negative electrode plate, which will be described later. Specifically, the electrode body 200 is a wound-type electrode body in which a band-shaped positive electrode plate and a band-shaped negative electrode plate are both wound via a band-shaped separator (not shown). However, in this specification, the "electrode body" is not limited to a wound-type electrode body, and may be a laminated electrode body in which a plurality of positive electrode plates and a plurality of negative electrode plates are alternately laminated. The band-shaped separator may be composed of, for example, a polyolefin microporous film. The electrode body may include a plurality of positive electrode plates and a plurality of negative electrode plates, and the positive electrode tabs provided on each positive electrode plate may be laminated to form a positive electrode tab group, or the negative electrode tabs provided on each negative electrode plate may be laminated to form a negative electrode tab group.

[0045] 6, 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.

[0046] Specifically, one or more wound electrode bodies are housed together with an electrolytic solution (electrolyte) (not shown) inside an insulating sheet 700 (described later) arranged in the case 100. As the electrolytic solution (non-aqueous electrolytic solution), for example, LiPF6 dissolved at a concentration of 1.2 mol / L in a non-aqueous solvent in which ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed in a volume ratio (25°C) of 30:30:40 can be used. Note that a solid electrolyte may be used instead of the electrolytic solution.

[0047] The electrode body 200 includes a main body portion (a portion in which positive electrode plates and negative electrode plates are stacked with a separator therebetween), a negative electrode tab group 220 (first electrode tab group), and a positive electrode tab group 250 (second electrode tab group). The main body portion of the electrode body 200 corresponds to a rectangular portion excluding the negative electrode tab group 220 and the positive electrode tab group 250.

[0048] The main body is composed of a negative electrode plate 210 and a positive electrode plate 240, which will be described later. The negative electrode tab group 220 is located at an end of a first side of the electrode body 200 in a first direction (X direction) with respect to the main body. The first side in this embodiment is the first sealing plate 120 side. The positive electrode tab group 250 is located at an end of a second side in the first direction (X direction) with respect to the main body. The second side in this embodiment is the second sealing plate 130 side.

[0049] 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 first sealing plate 120 or the second sealing plate 130, respectively.

[0050] 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 body 200 is electrically connected to the negative electrode terminal 301 and the positive electrode terminal 302 via the current collector 400.

[0051] The negative electrode current collector 410 is disposed on the first sealing plate 120 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. 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.

[0052] The positive electrode current collector 420 is disposed on the second sealing plate 130 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. 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. The positive electrode tab group 250 may be electrically connected to the second sealing plate 130 directly or via the positive electrode current collector 420. In this case, the second sealing plate 130 may play the role of the positive electrode terminal 302.

[0053] (Configuration of electrode body 200) FIG. 7 is a front view showing the negative electrode original plate 210S before the negative electrode plate 210 (first electrode) is formed, FIG. 8 is a cross-sectional view taken along line VIII-VIII of the negative electrode original plate 210S shown in FIG. 7, and FIG. 9 is a front view showing the negative electrode plate 210 formed from the negative electrode original plate 210S.

[0054] The negative electrode plate 210 is manufactured by processing a negative electrode original plate 210S. As shown in Figures 7 and 8, the negative electrode original plate 210S includes a negative electrode core 211 and a negative electrode active material layer 212. The negative electrode core 211 is a copper foil or a copper alloy foil.

[0055] A negative electrode active material layer 212 is formed on both sides of the negative electrode core 211 except for one end portion. The negative electrode active material layer 212 is formed by applying a negative electrode active material layer slurry with a die coater.

[0056] 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.

[0057] The negative electrode core 211 coated with the negative electrode active material layer slurry is dried to remove water contained in the negative electrode active material layer slurry, thereby forming the negative electrode active material layer 212. Furthermore, the negative electrode active material layer 212 is compressed to form a negative electrode original plate 210S including the negative electrode core 211 and the negative electrode active material layer 212. The negative electrode original plate 210S is cut into a predetermined shape to form the negative electrode plate 210. The negative electrode original plate 210S can be cut by laser processing using energy beam irradiation, die processing, cutter processing, or the like.

[0058] As shown in FIG. 9, a plurality of negative electrode tabs 230 made of a negative electrode core 211 are provided at one end in the width direction of a negative electrode plate 210 formed from a negative electrode original plate 210S. When the negative electrode plate 210 is wound, the plurality of negative electrode tabs 230 are stacked to form a 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 appropriately adjusted in consideration of 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 tab 230 is not limited to the one exemplified in FIG. 9.

[0059] FIG. 10 is a front view showing a positive electrode original plate 240S before the positive electrode plate 240 (second electrode) is formed, FIG. 11 is a cross-sectional view taken along line XI-XI of the positive electrode original plate 240S shown in FIG. 10, and FIG. 12 is a front view showing a positive electrode plate 240 formed from the positive electrode original plate 240S.

[0060] 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 original plate 240S. As shown in Fig. 10 and Fig. 11, the positive electrode original 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.

[0061] A positive electrode active material layer 242 is formed on both sides 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 with a die coater.

[0062] 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.

[0063] The positive electrode protective layer 243 is in contact with the positive electrode core 241 and is formed at one end in the width direction of the positive electrode active material layer 242. The positive electrode protective layer 243 is formed on the positive electrode core 241 by applying a positive electrode protective layer slurry with a die coater. The positive electrode protective layer 243 has a larger electric resistance than the positive electrode active material layer 242.

[0064] 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.

[0065] The positive electrode core 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 to form the positive electrode active material layer 242 and the positive electrode protective layer 243. Furthermore, the positive electrode active material layer 242 is compressed to form a positive electrode original plate 240S including the positive electrode core 241, the positive electrode active material layer 242, and the positive electrode protective layer 243. The positive electrode original plate 240S is cut into a predetermined shape to form the positive electrode plate 240. The positive electrode original plate 240S can be cut by laser processing using energy beam irradiation, die processing, cutter processing, or the like.

[0066] As shown in FIG. 12, a plurality of positive electrode tabs 260 made of a positive electrode core 241 are provided at one end in the width direction of the positive electrode plate 240 formed from the 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 in consideration of the state in which the positive electrode tab group 250 is connected to the positive electrode current collector 420. The shape of the positive electrode tab 260 is not limited to the one exemplified in FIG. 12.

[0067] A positive electrode protection layer 243 is provided at the base of each of the positive electrode tabs 260. The positive electrode protection layer 243 does not necessarily have to be provided at the base of the positive electrode tab 260.

[0068] 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.

[0069] (Connection structure between electrode body 200 and current collector 400) Fig. 13 is a diagram showing the electrode body 200 and the current collector 400 taken out from the secondary battery 1. As shown in Fig. 13, the electrode body 200 is formed by stacking two electrode bodies 201, 202, each of which is a wound type electrode body. In the example shown in Fig. 13, a structure in which two wound type electrode bodies are stacked is shown, but the electrode body 200 may be composed of one wound type electrode body, may be composed of three or more wound type electrode bodies, or may be composed of a laminated type electrode body.

[0070] The negative electrode tab group 220 is joined to the negative electrode current collector 410 at joint points 434 , and the positive electrode tab group 250 is joined to the positive electrode current collector 420 at joint points 454 .

[0071] Fig. 14 is a front view of the connection structure between the negative electrode tab group and the negative electrode current collector, and Fig. 15 is a cross-sectional view of the connection structure between the negative electrode tab group and the negative electrode current collector.

[0072] 14 and 15, 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 first sealing plate 120.

[0073] 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 portion 433. The first conductive member 430 and the second conductive member 440 are joined by, for example, laser welding.

[0074] The first conductive member 430 is joined to the negative electrode tab group 220 at a joint 434. The joint 434 can be formed by, for example, ultrasonic welding, resistance welding, laser welding, crimping, etc. In the present embodiment, the first conductive member 430 and the negative electrode tab group 220 are joined by, for example, ultrasonic bonding.

[0075] Second conductive member 440 is connected to negative terminal 301 at joint 441. Joint 441 may be formed by, for example, ultrasonic welding, resistance welding, laser welding, crimping, or the like. In this embodiment, negative terminal 301 and second conductive member 440 are joined by, for example, providing a through hole in second conductive member 440, inserting negative terminal 301 into the through hole, crimping negative terminal 301 onto second conductive member 440, and then welding the crimped portion to second conductive member 440.

[0076] The first conductive member 430 has a first planar portion 431 and a second planar portion 432. The first planar portion 431 is connected to the second conductive member 440. The second planar portion 432 is connected to the negative electrode tab group 220. The second planar portion 432 is disposed along the first sealing plate 120.

[0077] A step portion 435 is provided between the first flat portion 431 and the second flat portion 432. The step portion 435 makes the positions of the first flat portion 431 and the second flat portion 432 in the first direction (X direction) different 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).

[0078] A first insulating member 510 (resin member) is disposed between the negative electrode terminal 301 and the first sealing plate 120. A second insulating member 520 (resin member) is disposed between the first sealing plate 120 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.

[0079] Negative electrode terminal 301 is attached to first sealing plate 120 via first insulating member 510. Negative electrode terminal 301 is provided so as to be exposed to the outside of first sealing plate 120 and to reach second conductive member 440 of negative electrode current collector 410 provided on the inner surface side of first sealing plate 120.

[0080] The procedure for assembling each part is as follows: first, the negative electrode terminal 301 and the second conductive member 440 are attached to the first sealing plate 120 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 with 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.

[0081] However, negative electrode terminal 301 may be electrically connected to first sealing plate 120. Also, first sealing plate 120 may play the role of negative electrode terminal 301.

[0082] 14 and 15, the negative electrode current collector 410 is illustrated as being made up of two components (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 component.

[0083] Although the connection structure on the negative electrode side is shown in FIG. 14 and FIG. 15, the basic connection structure on the positive electrode side is similar to that on the negative electrode side.

[0084] (Step of Inserting the Electrode Body 200) 16 is a diagram showing a process of inserting the electrode body 200 into the case body 110. As shown in FIG. 16, a resin insulating sheet 700 (electrode body holder) is disposed between the electrode body 200 and the case body 110.

[0085] The insulating sheet 700 may be made of, for example, resin. More specifically, the material of the insulating sheet 700 may be, for example, polypropylene (PP), polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polyimide (PI), or polyolefin (PO).

[0086] The insulating sheet 700 does not necessarily have to cover the entire surface of the electrode body 200. The insulating sheet 700 preferably covers an area of ​​about 50% or more, and more preferably about 70% or more, of the outer surface of the electrode body. Of the six faces of the approximately rectangular parallelepiped (flat) electrode body 200, the insulating sheet 700 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.

[0087] FIG. 17 is a diagram showing a process of placing a first spacer 600 between the first sealing plate 120 and the electrode body 200. As shown in FIG.

[0088] 17, the negative electrode tab group 220 arranged from the electrode body 200 toward the first sealing plate 120 is curved from the center in the Y direction of the first sealing plate 120 toward the end, and then bent 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 body 200 and the first sealing plate 120.

[0089] 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 engagement portions 630A, 630B when the first component 610 and the second component 620 are slid along the Y direction from the end side toward the center side of the first sealing plate 120. As a result, the first spacer 600 is fixed to the first sealing plate 120 via the second insulating member 520, and the positional stability of the first spacer 600 is increased.

[0090] The secondary battery 1 according to this embodiment includes a second spacer (not shown). The second spacer is disposed between the electrode body and the second sealing plate. The second spacer may have a similar structure to the first spacer 600. The first spacer 600 and the second spacer may have different shapes.

[0091] (Manufacture of case body 110) Fig. 18 is a diagram showing a plate-like member 110A constituting the case body 110. Fig. 19 is a diagram showing a state in which the plate-like member 110A is folded.

[0092] As shown in Fig. 18, the plate-like member 110A is folded along the folding portion 110B. This forms a tubular shape having a pair of second side portions 112 as shown in Fig. 19. Here, the portion where two end sides 110C parallel to the folding portion 110B are butted together forms the joint portion 115. The vicinities of the two end sides 110C may be overlapped and joined in the thickness direction of the plate-like member 110A.

[0093] In the pair of second side surface portions 112, a gas exhaust valve 150 is provided on the top surface portion 112A, and a joint portion 115 is provided on the bottom surface portion 112B. The gas exhaust valve 150 is configured by a thin-walled portion or a groove portion provided on the top surface portion 112A of the case body 110. The gas exhaust valve 150 can be formed by pressing, cutting, or the like. The gas exhaust valve 150 is preferably formed by pressing. When the gas exhaust valve 150 is formed by pressing, the shape of the thin-walled portion or the groove portion is stable, and therefore, more stable rupture strength of the gas exhaust valve 150 can be obtained.

[0094] It is also possible to provide a gas exhaust valve in the case body by joining a part including a portion that serves as a gas exhaust valve to the case body. For example, a through hole can be provided in the case body, a part including a portion that serves as a gas exhaust valve can be disposed so as to close the through hole, and the part can be joined to the case body by welding or the like.

[0095] The gas exhaust valve 150 may be formed in the state of the plate-shaped member 110A shown in FIG. 18 (flat state before bending), or in the state shown in FIG. 19 (cylindrical state after bending), or some or all of the processing may be performed simultaneously with the bending processing of the plate-shaped member 110A.

[0096] When the gas release valve 150 is formed on the plate-like member 110A before bending, it is possible to more effectively prevent the case body 110 from being deformed due to distortion caused by the process of forming the gas release valve 150.

[0097] When the gas release valve 150 is formed in the state after bending, deformation of the gas release valve 150 due to bending can be effectively suppressed.

[0098] (Configuration of the insulating sheet 700) FIG. 20 is a diagram showing an example of the arrangement of the electrode body 200 and the insulating sheet 700 inside the case body 110. As shown in FIG.

[0099] 20, the insulating sheet 700 is provided so as to cover the outer periphery of the electrode body 200. Note that the insulating sheet 700 may leave part of the electrode body 200 exposed.

[0100] The insulating sheet includes a first end edge 701 and a second end edge 702 extending in the X direction. Here, one end edge of one insulating sheet 700 is the first end edge 701, and the other end edge of one insulating sheet 700 is the second end edge 702. In the example shown in Fig. 20, the first end edge 701 and the second end edge 702 are disposed at a position facing the upper surface portion 112A of the case main body 110. An overlapping region 710 in which the insulating sheet 700 is overlapped twice is provided between the first end edge 701 and the second end edge 702.

[0101] In this way, by arranging the first end edge 701 and the second end edge 702 of the insulating sheet 700 so as to face the upper surface portion 112A on which the gas exhaust valve 150 is provided, gas generated in the electrode body 200 can easily move through the gap in the overlapping region 710 toward the gas exhaust valve 150.

[0102] It is preferable that the insulating sheet 700 is not completely adhered or welded in the overlapping region 710. In this way, the above-mentioned gas exhaust path can be stably formed. By adhering or welding the overlapped insulating sheets 700 to each other at a plurality of mutually spaced locations in the overlapping region 710, the cylindrical shape of the insulating sheet 700 can be stably maintained.

[0103] Fig. 21 is a development view of insulating sheet 700. As shown in Fig. 21, insulating sheet 700 is formed into a tubular shape by folding sheet material 700A along folding portion 700B.

[0104] Fig. 22 is a front view showing the electrode body 200 and the insulating sheet 700. As shown in Fig. 22, the insulating sheet 700 is preferably provided so as to cover the entire main body portion 270 (excluding the negative electrode tab group 220 and the positive electrode tab group 250) of the electrode body 200 and the base portions of the negative electrode tab group 220 and the positive electrode tab group 250. In other words, the width of the insulating sheet 700 in the X direction is larger than the width of the main body portion 270 of the electrode body 200 in the X direction.

[0105] This makes it possible to more effectively prevent damage to the electrode body 200. Furthermore, as shown in Fig. 20, by providing the overlapping region 710 of the insulating sheet 700 on the gas release valve 150 side, gas escape from the inner periphery of the insulating sheet 700 toward the gas release valve 150 is improved, and the gas release valve 150 can be operated more stably.

[0106] Fig. 23 is a diagram showing a modified example of the arrangement of the electrode body and the separator inside the case body 110. In the example shown in Fig. 23, the overlapping region 710 of the insulating sheet 700 is provided in a region that does not overlap with the gas release valve 150 when viewed from the Z direction (a region shifted in the Y direction).

[0107] 23, the opening of the overlap region 710 is close to the gas release valve 150, and the gas release path from the inner periphery of the insulating sheet 700 to the gas release valve 150 is further shortened. Moreover, the overlap region 710 is not formed directly below the gas release valve 150. In this way, the gas release property toward the gas release valve 150 can be further improved.

[0108] However, the configuration of the insulating sheet 700 is not limited to those shown in Figures 20 to 23. Moreover, the insulating sheet 700 is not necessarily an essential component of the present technology.

[0109] (Arrangement of gas exhaust valve 150) Fig. 24 is a diagram showing the upper part of the electrode body 200. As shown in Fig. 24, the two electrode bodies 201, 202 included in the electrode body 200 are both wound type electrode bodies. The electrode bodies 201, 202 are adjacent to each other. The electrode body 201 (first electrode body) includes a curved surface 201A (first curved surface) facing the upper surface portion 112A of the case body 110, and the electrode body 202 (second electrode body) includes a curved surface 202A (second curved surface) facing the upper surface portion 112A of the case body 110.

[0110] 24, when viewed from the X direction, the curved surfaces 201A, 202A each have a first vertex A1 and a second vertex A2 that are closest to the upper surface portion 112A. The first vertex A1 and the second vertex A2 are separated by a distance D1 in the Y direction. Here, when the region located between the first vertex A1 and the second vertex A2 is defined as "region A," it is preferable that at least a part of the gas release valve 150 (more preferably, a part that becomes the starting point of rupture) is located in region A. It is preferable that, when viewed from the Z direction, 50 percent or more, more preferably 70 percent or more of the area of ​​the gas release valve 150 is located in region A.

[0111] More preferably, when the regions shifted inward by D1 / 6 from the first vertex A1 and the second vertex A2, respectively, as shown in FIG. 24, are defined as "region B," at least a portion of the gas exhaust valve 150 (more preferably, the portion that serves as the starting point for opening) is located in region B, and when viewed from the Z direction, 50 percent or more, more preferably 70 percent or more of the area of ​​the gas exhaust valve 150 is located in region B.

[0112] Figures 25 to 33 are diagrams showing examples of the arrangement of gas release valves 150 on upper surface portion 112A of case body 110. In Figures 25 to 33, the two-dot chain lines correspond to the diagonals of rectangular upper surface portion 112A.

[0113] The length ratio between the short side and the long side of the rectangular upper surface portion 112A on which the gas exhaust valve 150 is provided is preferably about 1:6 to 1:30.

[0114] 25, the gas release valve 150 includes a first portion 151 extending in the X direction (longitudinal direction) and a second portion 152 extending in the Y direction (transverse direction). The first portion 151 and the second portion 152 intersect at the center (intersection of diagonals) of the upper surface portion 112A.

[0115] When the length of the case body 110 in the X direction is L1 and the length of the first portion 151 of the gas release valve 150 is L2, L2 / L1 is preferably greater than 0.5, and more preferably greater than 0.6.

[0116] This ensures a relatively large opening area of ​​the gas exhaust valve 150, and therefore allows gas to be more effectively exhausted when the gas exhaust valve 150 breaks. When the gas exhaust valve 150 opens, it is preferable that the breakage occurs over a length of about 2 / 3L1 or more.

[0117] Furthermore, by further providing a second portion 152 that intersects (is perpendicular to) the first portion 151, the second portion 152 can be broken in addition to the first portion 151, thereby further increasing the opening area of ​​the gas exhaust valve 150.

[0118] The remaining thickness of the groove (thin portion) constituting the gas release valve 150 can be changed depending on the position. For example, the remaining thickness can be made relatively thin (the groove can be formed deep) around the intersection of the first portion 151 and the second portion 152. When the internal pressure of the case 100 rises, a relatively large stress occurs on the diagonal of the upper surface portion 112A, and a relatively large deformation occurs in that portion. By providing a portion with a thin remaining thickness on the diagonal of the upper surface portion 112A, the portion with a large deformation (large stress) can be made thin, that is, the stress concentration portion and the strength weakened portion can be made to coincide with each other, and the breaking point and breaking strength of the gas release valve 150 can be stabilized. As a result, the operating pressure of the gas release valve 150 can be stabilized, and the reliability of the gas release valve 150 can be improved.

[0119] 26 and 27, the gas exhaust valve 150 includes a first portion 151 extending in the X direction (longitudinal direction) and two second portions 152 spaced apart from each other. In the example of FIGS. 26 and 27, the two second portions 152 are connected to the first portion 151 at both ends of the first portion 151 in the X direction, but the second portions 152 may be connected to a portion other than both ends of the first portion 151 in the X direction. In addition, the shapes of the two second portions 152 are not limited to those exemplified in FIGS. 26 and 27.

[0120] In the example shown in FIG. 28, the gas exhaust valve 150 is disposed in a substantially X-shape along the diagonal line of the upper surface portion 112A.

[0121] 29, the gas exhaust valve 150 includes a first portion 151 extending in the Y direction (short direction) and two second portions 152 extending in the X direction (longitudinal direction). In the example of Fig. 28, the two second portions 152 are connected to the first portion 151 at both ends of the first portion 151 in the Y direction, but the second portions 152 may be connected to a portion other than both ends of the first portion 151 in the Y direction.

[0122] 30 to 33, the gas exhaust valve 150 is arranged in a plurality of regions separated from each other. In the example of Fig. 30 to 33, two separate gas exhaust valves 150 are arranged so as to reach the ends of the upper surface portion 112A in the X direction. The gas exhaust valve may be arranged in three or more regions.

[0123] In the example of Fig. 30, the two gas exhaust valves 150 are each formed linearly so as to extend in the X direction (longitudinal direction), and in the examples of Fig. 31 and Fig. 33, the two gas exhaust valves 150 are each formed substantially in a cross shape. In the example of Fig. 32, the two gas exhaust valves 150 are each formed substantially in a U shape so as to open toward the end side in the X direction.

[0124] In the example of Fig. 33, the gas release valve 150 is disposed inside a recess 160 (thin region) formed in the upper surface portion 112A. Fig. 34 is a cross-sectional view taken along line XXXIV-XXXIV in Fig. 33. As shown in Fig. 34, the recess 160 is formed so that the thickness of the case body 110 is relatively small, and therefore the amount of deformation when the internal pressure of the case 100 increases is relatively large. Therefore, by forming the gas release valve 150 inside the recess 160, the gas release valve 150 can be operated more stably when the internal pressure of the case 100 increases.

[0125] The length of each gas release valve 150 is preferably about 1 / 15 or more of the length L1 (FIG. 25) of the case body 110, more preferably about 1 / 8 or more, and even more preferably about 1 / 5 or more.

[0126] The arrangement of the gas exhaust valve 150 is not limited to those shown in Figures 25 to 34. It is also possible to use a combination of the configurations exemplified in Figures 25 to 34.

[0127] Fig. 35 is an enlarged cross-sectional view showing an example of a groove portion that constitutes the gas release valve 150. As shown in Fig. 35, the groove portion that constitutes the gas release valve 150 is formed on the outer surface of the case body 110. However, the groove portion may also be formed on the inner surface of the case body 110.

[0128] By forming the groove that constitutes the gas release valve 150 on the outer surface of the case body 110, it is possible to prevent the electrode body 200 from getting caught (interfering) with the groove when inserting the electrode body 200 into the case body 110. On the other hand, when the groove is formed on the inner surface of the case body 110, the surface of the groove is protected after the electrode body 200 is inserted into the case body 110 and sealed with the first sealing plate 120 and the second sealing plate 130, so that the operating pressure of the gas release valve 150 can be made more stable.

[0129] 35, the gas release valve 150 is configured by a groove having a substantially V-shape. In one example, the open angle θ of the substantially V-shape is approximately 60° or more and 90° or less. However, the shape of the groove that configures the gas release valve 150 is not limited to that shown in FIG 35, and the gas release valve 150 may be configured by a groove having, for example, a substantially rectangular cross-sectional shape.

[0130] FIG. 36 is a diagram for explaining the arrangement of the gas exhaust valve 150 in the X direction (first direction).

[0131] As shown in FIG. 36, the electrode body 200 includes a main body portion 270, and a negative electrode tab group 220 and a positive electrode tab group 250 that protrude from the main body portion 270 towards the first sealing plate 120 and the second sealing plate 130, respectively.

[0132] The upper surface portion 112A of the case body 110 has a region R270 facing the main body portion 270 of the electrode body 200, an end region R120 located closer to the first sealing plate 120 than the main body portion 270, and an end region R130 located closer to the second sealing plate 130 than the main body portion 270. At least a portion of the gas release valve 150 is disposed so as to reach the end regions R120, R130.

[0133] In one example, the length of each of the end regions R120 and R130 in the X direction is about 12 mm±1 mm. The length of the end regions R120 and R130 is, for example, about ⅕ or less of the length L1 of the case body 110.

[0134] The gas exhaust valve 150 is formed so as to extend from the boundary between the region R270 and the end regions R120, R130 to a position that is moved outward (toward the first sealing plate 120 and second sealing plate 130) by a length that is, for example, approximately 50 percent or more of the length of the end regions R120, R130.

[0135] In this way, by positioning the gas release valve 150 so that it reaches the end regions R120, R130 located at both ends in the X direction, when the internal pressure of the case 100 increases, gas can flow to the gas release valve 150 through the gaps above the negative electrode tab group 220 and the positive electrode tab group 250, so that the gas release valve 150 can be broken more smoothly to release the gas.

[0136] (Action and effect) According to the secondary battery 1 of this embodiment, by inserting the electrode body 200 into the case body 110 having a first opening 113 and a second opening 114 facing each other, and by sealing the first opening 113 and the second opening 114, the height of the secondary battery 1 can be reduced, resulting in a secondary battery 1 that has a high capacity and is easily mountable in a vehicle.

[0137] In addition, by providing a gas exhaust valve 150 on top surface 112A of case body 110 and providing a joint portion 115 on bottom surface 112B opposite top surface 112A, gas exhaust valve 150 and joint portion 115 can be spaced apart on different sides of case body 110, thereby stabilizing the operating pressure of gas exhaust valve 150. As a result, a high-capacity, highly reliable secondary battery 1 can be provided.

[0138] Alternatively, gas exhaust valve 150 may be provided on bottom surface 112B of case body 110, and joint portion 115 may be provided on top surface 112A opposite bottom surface 112B.

[0139] Furthermore, as shown in Figures 20 and 23, by facing the overlapping area 710 of the insulating sheet 700 to the upper surface portion 112A on which the gas exhaust valve 150 is provided, gas generated inside the electrode body 200 can flow smoothly toward the gas exhaust valve 150.

[0140] 24, by arranging at least a part of the gas release valve 150 in the region A or region B located between the first vertex A1 and the second vertex A2 of the adjacent electrode bodies 201, 202, the gas generated inside the electrode body 200 can be made to flow smoothly toward the gas release valve 150. Therefore, the operating pressure of the gas release valve 150 can be further stabilized.

[0141] In the present embodiment, an example has been described in which the centers of the negative electrode tab group 220 and the positive electrode tab group 250 are provided near the center in the Z direction of the electrode body 200, but the centers of the negative electrode tab group 220 and the positive electrode tab group 250 may be disposed on the opposite side to the gas release valve 150 (upper surface portion 112A), that is, shifted downward in the Z direction (toward the bottom surface portion 112B). In this way, a gas release path leading to the gas release valve 150 is more easily secured.

[0142] In the example of FIG. 2, the joint 115 is provided at the center of the bottom surface portion 112B in the Y direction. In the Y direction, the joint 115 can be disposed at a position shifted from the center of the bottom surface portion 112B toward either end side (either one side of the two long ends of the bottom surface portion 112B). In this case, even if the internal pressure in the case 100 increases, damage to the joint 115 is more reliably suppressed by shifting the joint 115 from the portion where stress is likely to concentrate. Therefore, the gas exhaust valve 150 operates more stably. In particular, it is preferable that the portion of the joint 115 located at the center of the bottom surface portion 112B in the X direction has such a configuration.

[0143] Although the embodiment of the present technology has been described above, the embodiment disclosed herein should be considered as illustrative and not restrictive in all respects. The scope of the present technology is defined by the claims, and it is intended to include all modifications within the scope and meaning equivalent to the claims. [Explanation of symbols]

[0144] 1 secondary battery, 100 case, 110 case body, 110A plate-like member, 110B bent portion, 110C edge, 111 first side portion, 112 second side portion, 112A top surface portion, 112B bottom surface portion, 113 first opening, 114 second opening, 115 joint portion, 120 first sealing plate, 121 liquid injection hole, 130 second sealing plate, 131 liquid injection hole, 150 gas exhaust valve, 151 first portion, 152 second portion, 160 recess, 200, 201, 202 electrode body, 201A, 202A curved surface, 210 negative electrode plate, 210S negative electrode base plate, 211 negative electrode core body, 212 negative electrode active material layer, 220 negative electrode tab group, 230 negative electrode tab, 240 Positive electrode plate, 240S, positive electrode original plate, 241, positive electrode core body, 242, positive electrode active material layer, 243, positive electrode protective layer, 250, positive electrode tab group, 260, positive electrode tab, 270, main body, 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, joint portion, 435, step portion, 440, second conductive member, 441, joint portion, 454, joint portion, 510, first insulating member, 520, second insulating member, 600, first spacer, 610, first part, 620, second part, 630A, 630B, engagement portion, 700, insulating sheet, 700A Sheet material, 700B folded portion, 701 first edge, 702 second edge, 710 overlapping area.

Claims

1. An electrode assembly including a first electrode and a second electrode having a polarity different from that of the first electrode; A case for accommodating the electrode body, The case is a case body having a first opening located at an end of a first side in a first direction and a second opening located at an end of a second side opposite to the first side in the first direction; a first sealing plate that seals the first opening; a second sealing plate that seals the second opening, the case body includes a pair of first walls facing each other in a second direction perpendicular to the first direction, and a pair of second walls perpendicular to each other in a third direction perpendicular to each other in the first direction and the second direction, and an area of ​​the pair of first walls is larger than an area of ​​the pair of second walls; a gas exhaust valve that breaks when the pressure inside the case reaches or exceeds a predetermined value is provided on one of the pair of second walls; A secondary battery, wherein the other of the pair of second walls is provided with a joint portion extending in the first direction.

2. The secondary battery according to claim 1 , wherein the gas release valve includes a thinned portion or a groove formed in one of the pair of second walls.

3. the electrode body includes a body portion, a first electrode tab electrically connected to the first electrode and located on the first side with respect to the body portion, and a second electrode tab electrically connected to the second electrode and located on the second side with respect to the body portion, the first electrode tab is electrically connected to a first electrode terminal provided on the first sealing plate; The secondary battery according to claim 1 , wherein the second electrode tab is electrically connected to a second electrode terminal provided on the second sealing plate.

4. the electrode body includes a body portion, a first electrode tab electrically connected to the first electrode and located on the first side with respect to the body portion, and a second electrode tab electrically connected to the second electrode and located on the second side with respect to the body portion, At least a portion of the gas exhaust valve is disposed in a first end region that is closer to the first opening than the main body portion of the electrode body in the first direction, 3 . The secondary battery according to claim 1 , wherein at least a portion of the gas release valve is disposed in a second end region that is closer to the second opening than the main body portion of the electrode body in the first direction.

5. the electrode body includes a first electrode body and a second electrode body, each of the first electrode body and the second electrode body being a wound electrode body; The first electrode body and the second electrode body are disposed adjacent to each other, the first electrode body includes a first curved surface facing one of the pair of second walls, the first curved surface having a first apex closest to the one of the pair of second walls; the second electrode body includes a second curved surface facing one of the pair of second walls, the second curved surface having a second apex closest to the one of the pair of second walls; 3 . The secondary battery according to claim 1 , wherein at least a portion of the gas release valve is disposed in a region located between the first apex and the second apex in the second direction.

6. Further, an insulating sheet is provided which covers at least a part of the outer periphery of the electrode body, the insulating sheet includes a first end side and a second end side extending in the first direction, the first end edge and the second end edge are disposed at positions facing one of the pair of second walls, The secondary battery according to claim 1 or 2, wherein a region in which the insulating sheet is overlapped twice is provided between the first end side and the second end side.

7. The secondary battery according to claim 1 , wherein the gas release valve is arranged in a plurality of separate regions on one of the pair of second walls.

8. a thin-walled region in which the thickness of the case body is relatively small is formed in one of the pair of second walls, The secondary battery according to claim 1 , wherein the gas release valve is disposed inside the thin-walled region.

9. 3 . The secondary battery according to claim 1 , wherein the joint portion is disposed at a position shifted toward either end side from a center of the other of the pair of second walls in the second direction.

Images