Secondary batteries

Abstract

To provide high-capacity and reliable rechargeable batteries. [Solution] The secondary battery comprises an electrode body including a first electrode and a second electrode having a different polarity from the first electrode, and a case for housing the electrode body. The case has a case body having a first opening located at the end of the first side in the first direction and a second opening located at the end of the second side opposite to the first side in the first direction, a first sealing plate for sealing the first opening and a second sealing plate for sealing 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 facing each other in a third direction perpendicular to the first and second directions. The area of ​​the pair of first walls is larger than the area of ​​the pair of second walls. A gas release valve is provided on one of the pair of second walls that ruptures when the pressure inside the case exceeds a predetermined value, and a joint extending in the first direction is provided on the other of the pair of second walls.

Description

Technical Field

[0001] This technology relates to secondary batteries.

Background Art

[0002] Japanese Patent Application Laid-Open No. 2001-143664 (Patent Document 1) discloses forming a thin portion on any side surface other than the terminal surface and the bottom surface of a rectangular case to serve as a safety valve.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] With the increase in the capacity of batteries, the size of secondary batteries is increasing. From the perspective of reliability in large secondary batteries, there is room for further improvement in the batteries described in Patent Document 1. The object of this technology is to provide a high-capacity and highly reliable secondary battery.

Means for Solving the Problems

[0005] This technology provides the following secondary battery.

[0006] [1] An electrode body comprising a first electrode and a second electrode having a different polarity from the first electrode, and a case housing the electrode body, the case having a case body having a first opening located at the end of the first side in the first direction and a second opening located at the end of the second side opposite to the first side in the first direction, a first sealing plate sealing the first opening and a second sealing plate sealing the second opening, the case body comprising a pair of first walls facing each other in a second direction perpendicular to the first direction and a pair of second walls facing each other in a third direction perpendicular to the first and second directions, the area of ​​the pair of first walls being larger than the area of ​​the pair of second walls, a gas discharge valve provided on one of the pair of second walls that ruptures when the pressure inside the case exceeds a predetermined value, and a joint extending in the first direction provided on the other of the pair of second walls, the electrode body comprising a first electrode body and a second electrode body A secondary battery comprising a first electrode body and a second electrode body, each of which 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 has a first vertex closest to one of the pair of second walls, the second electrode body includes a second curved surface facing one of a pair of second walls, the second curved surface has a second vertex closest to one of the pair of second walls, at least a portion of a gas exhaust valve is arranged in a region located between the first and second vertices in a second direction, the first electrode body and the second electrode body each have a first electrode tab connected to the first electrode at the end on the first sealing plate side, the first electrode body and the second electrode body each have a second electrode tab connected to the second electrode at the end on the second sealing plate side, the length of the first wall in the first direction is 30 cm or more, and the length of the first wall in the third direction is 20 cm or less.

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

[0008] [3] A secondary battery according to [1] or [2], wherein the first electrode tab is electrically connected to the first electrode terminal provided on the first sealing plate, and the second electrode tab is electrically connected to the second electrode terminal provided on the second sealing plate.

[0009] [4] The secondary battery according to [1] or [2], wherein at least a portion of the gas exhaust valve is located in a first end region that is closer to the first opening than the main body of the first electrode body in a first direction, and at least a portion of the gas exhaust valve is located in a second end region that is closer to the second opening than the main body of the first electrode body in a first direction.

[0010] [5] The secondary battery according to any one of the items [1] to [4], wherein the gas exhaust valve is divided into multiple regions spaced apart from each other in one of a pair of second walls.

[0011] [6] A secondary battery according to any one of items [1] to [5], wherein a thin-walled region is formed on one of a pair of second walls, the thickness of which is relatively small compared to the case body, and a gas exhaust valve is located inside the thin-walled region.

[0012] [7] The secondary battery according to any one of [1] to [6], wherein in a second direction, the joint is positioned offset from the center of the other of the pair of second walls toward either end. [Effects of the Invention]

[0013] According to this technology, by providing a gas exhaust valve on one of a pair of opposing second walls and a joint extending in the first direction on the other, the gas exhaust valve and the joint are spaced apart on separate sides of the case body, thereby stabilizing the operating pressure of the gas exhaust valve. As a result, a high-capacity and reliable secondary battery can be provided. [Brief explanation of the drawing]

[0014] [Figure 1] This is a front view showing the configuration of a secondary battery according to one embodiment of this technology. [Figure 2] This figure shows the secondary battery shown in Figure 1 as viewed from the direction of arrow II. [Figure 3] This figure shows the secondary battery shown in Figure 1 as viewed from the direction of arrow III. [Figure 4] Figure 1 shows the secondary battery as viewed from the direction of arrow IV. [Figure 5] This is a view showing the secondary battery shown in FIG. 1 as seen from the direction of arrow V. [Figure 6] This is a front cross-sectional view of the secondary battery shown in FIG. 1. [Figure 7] This is a front view showing the negative electrode raw sheet before the negative electrode plate is formed. [Figure 8] This is a cross-sectional view taken along VIII-VIII of the negative electrode raw sheet shown in FIG. 7. [Figure 9] This is a front view showing the negative electrode plate formed from the negative electrode raw sheet. [Figure 10] This is a front view showing the positive electrode raw sheet before the positive electrode plate is formed. [Figure 11] This is a cross-sectional view taken along XI-XI of the positive electrode raw sheet shown in FIG. 10. [Figure 12] This is a front view showing the positive electrode plate formed from the positive electrode raw sheet. [Figure 13] This is a view showing the electrode body and the current collector taken out from the secondary battery. [Figure 14] This is a front view of the connection structure between the negative electrode tab group and the negative electrode current collector. [Figure 15] This is a cross-sectional view of the connection structure between the negative electrode tab group and the negative electrode current collector. [Figure 16] This is a view showing the process of inserting the electrode body into the case body. [Figure 17] This is a view showing the process of arranging a spacer between the sealing plate and the electrode body. [Figure 18] This is a view showing the plate-like member constituting the case body. [Figure 19] This is a view showing the state in which the plate-like member shown in FIG. 18 is bent. [Figure 20] This is a view showing an example of the arrangement of the electrode body and the insulating sheet inside the case body. [Figure 21] This is a developed view of the insulating sheet. [Figure 22] This is a front view showing the electrode body and the insulating sheet. [Figure 23] This is a view showing a modified example of the arrangement of the electrode body and the separator inside the case body. [Figure 24]This is a diagram showing the upper parts of multiple wound electrode bodies. [Figure 25] This is a diagram (part 1) showing the arrangement of the gas exhaust valves. [Figure 26] This is a diagram (part 2) showing the arrangement of the gas discharge valves. [Figure 27] This is diagram (part 3) showing the arrangement of the gas exhaust valves. [Figure 28] This is diagram (number 4) showing the arrangement of the gas exhaust valves. [Figure 29] This is diagram (number 5) showing the arrangement of the gas exhaust valves. [Figure 30] This is diagram (number 6) showing the arrangement of the gas exhaust valves. [Figure 31] This is diagram (number 7) showing the arrangement of the gas exhaust valves. [Figure 32] This is diagram (number 8) showing the arrangement of the gas discharge valves. [Figure 33] This is diagram (number 9) showing the arrangement of the gas exhaust valves. [Figure 34] Figure 33 shows a cross-sectional view taken between XXXIV and XXXIV. [Figure 35] This is an enlarged cross-sectional view showing an example of a groove that constitutes a gas exhaust valve. [Figure 36] This is a diagram illustrating the arrangement of the gas discharge valve in the first direction. [Modes for carrying out the invention]

[0015] Embodiments of this technology are described below. Note that the same or corresponding parts may be denoted by the same reference numerals, and their descriptions may not be repeated.

[0016] In the embodiments described below, when referring to the number, quantity, etc., unless otherwise specified, the scope of this technology is not necessarily limited to that number, quantity, etc. Also, in the embodiments described below, each component is not necessarily essential to this technology unless otherwise specified. Furthermore, this technology is not necessarily limited to achieving all of the effects and advantages mentioned in these embodiments.

[0017] In this specification, the terms "comprise," "include," and "have" are in open-ended form. That is, if a configuration includes one configuration, it may also include other configurations, or it may not.

[0018] Furthermore, where geometric terms and terms describing positional and directional relationships are used in this specification, such as "parallel," "orthogonal," "45° oblique," "coaxial," and "alongside," these terms allow for manufacturing tolerances or slight variations. Where terms describing relative positional relationships, such as "upper" and "lower," are used in this specification, these terms are used to indicate the relative positional relationship in a single state, and the relative positional relationship may be reversed or rotated to any angle depending on the installation direction of each mechanism (for example, by inverting the entire mechanism upside down).

[0019] In this specification, “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-state electrolyte secondary batteries. In this specification, “electrode” may refer collectively to the positive electrode and the negative electrode.

[0020] In the drawings, the direction along the winding axis of the electrode body of the secondary battery is designated as the X direction as the first direction, the Y direction is designated as the second direction as the direction perpendicular to the first direction and the short side of the electrode body as viewed from the first direction, and the Z direction is designated as the third direction as the direction perpendicular to the first direction and the long side of the electrode body as viewed from the first direction. Furthermore, in order to facilitate understanding of the invention, the dimensions of each component in the drawings have been changed from the actual dimensions in some cases.

[0021] In this specification, the first direction (X direction) may be referred to as the "width direction" of the secondary battery or case body, the second direction (Y direction) may be referred to as the "thickness direction" of the secondary battery or case body, and the third direction (Z direction) may be referred to as the "height direction" of the secondary battery or case body.

[0022] (Overall battery configuration) Figure 1 is a front view of the secondary battery 1 according to this embodiment. Figures 2 to 5 show the secondary battery 1 shown in Figure 1 as viewed from the directions of arrows II, III, IV, and V, respectively. Figure 6 is a front cross-sectional view of the secondary battery 1 shown in Figure 1.

[0023] The secondary battery 1 can be installed in electric vehicles (BEVs), plug-in hybrid electric vehicles (PHEVs), and hybrid electric vehicles (HEVs), etc. However, the use of the secondary battery 1 is not limited to automotive applications.

[0024] As shown in Figures 1 to 6, the secondary battery 1 includes a case 100, an electrode body 200, electrode terminals 300, and a current collector 400. The case 100 includes a case body 110, a first sealing plate 120, and a second sealing plate 130.

[0025] When a battery pack including a secondary battery 1 is constructed, multiple secondary batteries 1 are stacked in the 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 battery pack may be directly supported on the side of the battery pack case without using a restraining member.

[0026] The case body 110 consists 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, aluminum alloy, iron, or iron alloy.

[0027] As shown in Figures 1 and 2, a first sealing plate 120 and a second sealing plate 130 are provided at both ends of the case body, respectively. The case body 110 can be formed into a rectangular tube shape by, for example, bringing together the ends of bent plate-shaped members (joint portion 115 as illustrated in Figure 2) and joining them together (for example, by laser welding). The corners of the "rectangular tube" may have a rounded shape. In this embodiment, the joint portion 115 extends in a first direction (X direction) on the outer circumferential surface of the case body 110.

[0028] 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 makes it possible to construct 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 makes it possible to construct a relatively low-height secondary battery 1, which improves, for example, its mountability in a vehicle.

[0029] The case body 110 includes a pair of first side sections 111 (first walls) and a pair of second side sections 112 (second walls). The pair of first side sections 111 constitute a part of the side surface of the case 100. The pair of second side sections 112 constitute the top surface 112A and the bottom surface 112B of the case 100. Each of the pair of first side sections 111 and the pair of second side sections 112 is provided so as to intersect each other. The pair of first side sections 111 and the pair of second side sections 112 are connected at their respective ends. Each of the pair of first side sections 111 has a larger area than each of the pair of second side sections 112.

[0030] As shown in Figure 3, a first opening 113 is provided at the first side end of the case body 110 in the first direction (X direction). The first opening 113 is sealed by a first sealing plate 120. The first opening 113 and the first sealing plate 120 have a substantially rectangular shape with the Y direction being the short side and the Z direction being the long side.

[0031] A negative electrode terminal 301 (first electrode terminal) and an injection hole 121 are provided on the first sealing plate 120. The positions of the negative electrode terminal 301 and the injection hole 121 can be changed as appropriate. The first sealing plate 120 can be joined to the case body 110, for example, by laser welding.

[0032] As shown in Figure 4, a second opening 114 is provided at the end of the second side of the case body 110, opposite to the first side in the first direction (X direction). The second opening 114 is sealed by a second sealing plate 130. The second opening 114 and the second sealing plate 130 have a substantially rectangular shape, with the Y direction being the short side and the Z direction being the long side.

[0033] A positive electrode terminal 302 (second electrode terminal) and an injection hole 131 are provided on the second sealing plate 130. The positions of the positive electrode terminal 302 and the injection hole 131 can be changed as appropriate. The second sealing plate 130 can be joined to the case body 110, for example, by laser welding.

[0034] 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, aluminum alloy, iron, or iron alloy, etc.

[0035] In one example, the thickness of the first sealing plate 120 and the second sealing plate 130 are greater than the thickness (plate thickness) of the case body 110.

[0036] 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, i.e., the case 100.

[0037] The positive terminal 302 is electrically connected to the positive electrode of the electrode body 200. The positive terminal 302 is attached to the second sealing plate 130, i.e., the case 100.

[0038] The negative electrode terminal 301 is made of a conductive material (more specifically, a metal), such as copper or a copper alloy. A portion or layer made of aluminum or an aluminum alloy may be provided on the outer surface of the negative electrode terminal 301.

[0039] The positive terminal 302 is made of a conductive material (more specifically, a metal), which may be made of aluminum or an aluminum alloy, for example.

[0040] The injection holes 121 and 131 are sealed by a sealing member (not shown). For example, blind rivets and other metal members can be used as the sealing member.

[0041] As shown in Figure 5, a gas discharge valve 150 is provided on the upper surface 112A of the case 100. The gas discharge valve 150 is formed to extend in the X direction. The gas discharge valve 150 is a thin-walled portion formed on the upper surface 112A of the case 100. The gas discharge valve 150 ruptures when the pressure inside the case 100 exceeds a predetermined value, and discharges the gas inside the case 100 to the outside.

[0042] 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 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, "electrode body" is not limited to a wound-type electrode body, and may be a laminated-type electrode body in which multiple positive electrode plates and multiple negative electrode plates are alternately stacked. The strip-shaped separator can be made of, for example, a polyolefin microporous film. The electrode body may include multiple positive electrode plates and multiple negative electrode plates, and positive electrode tabs provided on each positive electrode plate may be stacked to form a group of positive electrode tabs, or negative electrode tabs provided on each negative electrode plate may be stacked to form a group of negative electrode tabs.

[0043] As shown in Figure 6, the case 100 houses the electrode body 200. The electrode body 200 is housed in the case 100 such that its winding axis is parallel to the X direction.

[0044] Specifically, one or more wound electrode bodies are housed inside the insulating sheet 700 (described later) placed within the case 100, together with an electrolyte (not shown). As the electrolyte (non-aqueous electrolyte), for example, a non-aqueous solvent prepared 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 can be used. Alternatively, a solid electrolyte may be used instead of the electrolyte.

[0045] The electrode body 200 includes a main body (the portion in which the positive electrode plate and the negative electrode plate are stacked with a separator in between), a negative electrode tab group 220 (first electrode tab group), and a positive electrode tab group 250 (second electrode tab group). The main body of the electrode body 200 corresponds to the rectangular portion excluding the negative electrode tab group 220 and the positive electrode tab group 250.

[0046] 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 the first side end of the electrode body 200 in the first direction (X direction) relative to the main body. In this embodiment, the first side is the side of the first sealing plate 120. The positive electrode tab group 250 is located at the second side end of the main body in the first direction (X direction). In this embodiment, the second side is the side of the second sealing plate 130.

[0047] The negative electrode tab group 220 and the positive electrode tab group 250 are formed to protrude from the central portion of the electrode body 200 toward the first sealing plate 120 or the second sealing plate 130, respectively.

[0048] 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 plate-shaped members. The electrode body 200 is electrically connected to the negative electrode terminal 301 and the positive electrode terminal 302 via the current collector 400.

[0049] The negative electrode current collector 410 is positioned 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), which may be made of copper or a copper alloy, for example.

[0050] The positive electrode current collector 420 is positioned 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), such as 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 also function as the positive electrode terminal 302.

[0051] (Configuration of electrode body 200) Figure 7 is a front view showing the negative electrode base plate 210S before the negative electrode plate 210 (first electrode) is formed, Figure 8 is a cross-sectional view of the negative electrode base plate 210S shown in Figure 7, and Figure 9 is a front view showing the negative electrode plate 210 formed from the negative electrode base plate 210S.

[0052] The negative electrode plate 210 is manufactured by processing the negative electrode base plate 210S. As shown in Figures 7 and 8, the negative electrode base plate 210S includes a negative electrode core 211 and a negative electrode active material layer 212. The negative electrode core 211 is copper foil or copper alloy foil.

[0053] The negative electrode core body 211 has a negative electrode active material layer 212 formed on both sides, except for one end. The negative electrode active material layer 212 is formed by applying a negative electrode active material slurry using a die coater.

[0054] The negative electrode active material layer slurry is prepared by kneading graphite as the negative electrode active material, styrene-butadiene rubber (SBR) and carboxymethylcellulose (CMC) as binders, and water as a dispersion medium, so that the mass ratio of graphite:SBR:CMC is approximately 98:1:1.

[0055] The negative electrode core 211, to which the negative electrode active material layer slurry has been applied, is dried to remove water contained in the negative electrode active material layer slurry, thereby forming the negative electrode active material layer 212. Furthermore, by compressing the negative electrode active material layer 212, a negative electrode base plate 210S containing the negative electrode core 211 and the negative electrode active material layer 212 is formed. The negative electrode plate 210 is formed by cutting the negative electrode base plate 210S into a predetermined shape. The negative electrode base plate 210S can be cut by laser processing using energy beam irradiation, mold processing, or cutter processing.

[0056] As shown in Figure 9, a plurality of negative electrode tabs 230, each made of a negative electrode core 211, are provided at one end in the width direction of the negative electrode plate 210 formed from the negative electrode base 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 protruding length of each of the plurality of negative electrode tabs 230 are appropriately adjusted considering the state in which the negative electrode tab group 220 is connected to the negative electrode current collector 410. Note that the shape of the negative electrode tabs 230 is not limited to that shown in Figure 9.

[0057] Figure 10 is a front view showing the positive electrode base plate 240S before the positive electrode plate 240 (second electrode) is formed, Figure 11 is a cross-sectional view of the positive electrode base plate 240S shown in Figure 10 from line XI, and Figure 12 is a front view showing the positive electrode plate 240 formed from the positive electrode base plate 240S.

[0058] The positive electrode plate 240, which is the second electrode, has a different polarity from 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 Figures 10 and 11, the positive electrode base plate 240S includes a positive electrode core 241, a positive electrode active material layer 242, and a positive electrode protective layer 243. The positive electrode core 241 is aluminum foil or aluminum alloy foil.

[0059] A positive electrode active material layer 242 is formed on the positive electrode core 241, except for one end on both sides. The positive electrode active material layer 242 is formed on the positive electrode core 241 by applying a positive electrode active material slurry using a die coater.

[0060] 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, carbon material as a conductive material, and N-methyl-2-pyrrolidone (NMP) as a dispersion medium, such that the mass ratio of lithium nickel cobalt manganese composite oxide:PVdF:carbon material is approximately 97.5:1:1.5.

[0061] 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 with a die coater. The positive electrode protective layer 243 has an electrical resistance greater than that of the positive electrode active material layer 242.

[0062] The positive electrode protective layer slurry is prepared by kneading alumina powder, carbon material as a conductive material, PVdF as a binder, and NMP as a dispersion medium, such that the mass ratio of alumina powder:carbon material:PVdF is approximately 83:3:14.

[0063] The positive electrode core 241, to which the positive electrode active material layer slurry and positive electrode protective layer slurry have been applied, is dried to remove NMP contained in the positive electrode active material layer slurry and positive electrode protective layer slurry, thereby forming the positive electrode active material layer 242 and positive electrode protective layer 243. Furthermore, by compressing the positive electrode active material layer 242, a positive electrode base plate 240S containing the positive electrode core 241, positive electrode active material layer 242, and positive electrode protective layer 243 is formed. The positive electrode plate 240 is formed by cutting the positive electrode base plate 240S into a predetermined shape. The positive electrode base plate 240S can be cut by laser processing using energy beam irradiation, mold processing, or cutter processing.

[0064] As shown in Figure 12, a plurality of positive electrode tabs 260, each made of a positive electrode core 241, are provided at one end in the width direction of the positive electrode plate 240 formed from the positive electrode base 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 protruding length of each of the plurality of positive electrode tabs 260 are appropriately adjusted considering 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 tabs 260 is not limited to that exemplified in Figure 12.

[0065] A positive electrode protective layer 243 is provided at the base of each of the multiple positive electrode tabs 260. A positive electrode protective layer 243 is not necessarily provided at the base of the positive electrode tabs 260.

[0066] In a typical example, the thickness of one negative electrode tab 230 is less than the thickness of one positive electrode tab 260. In this case, the thickness of the negative electrode tab group 220 is less than the thickness of the positive electrode tab group 250.

[0067] (Connection structure between electrode body 200 and current collector 400) Figure 13 shows the electrode body 200 and current collector 400 taken from the secondary battery 1. As shown in Figure 13, the electrode body 200 is formed by stacking two electrode bodies 201 and 202, each being a wound-type electrode body. In the example shown in Figure 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, or of three or more wound-type electrode bodies, or of a stacked electrode body.

[0068] The negative electrode tab group 220 is joined to the negative electrode current collector 410 at the joining point 434, and the positive electrode tab group 250 is joined to the positive electrode current collector 420 at the joining point 454.

[0069] Figure 14 is a front view of the connection structure between the negative electrode tab group and the negative electrode current collector. Figure 15 is a cross-sectional view of the connection structure between the negative electrode tab group and the negative electrode current collector.

[0070] As shown in Figures 14 and 15, the negative electrode current collector 410 electrically connects the negative electrode terminal 301 and the negative electrode tab group 220. In this embodiment, the negative electrode current collector 410 is connected to the negative electrode terminal 301 between the electrode body 200 and the first sealing plate 120.

[0071] 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, for example, by laser welding.

[0072] The first conductive member 430 is joined to the negative electrode tab group 220 at the joining point 434. The joining point 434 can be formed by, for example, ultrasonic welding, resistance welding, laser welding, crimping, etc. In this embodiment, the first conductive member 430 and the negative electrode tab group 220 are joined by, for example, ultrasonic bonding.

[0073] The second conductive member 440 is connected to the negative electrode terminal 301 at a joint 441. The joint 441 can be formed by, for example, ultrasonic welding, resistance welding, laser welding, crimping, etc. In this embodiment, the joining of the negative electrode terminal 301 and the second conductive member 440 is performed, for example, by providing a through hole in the second conductive member 440, inserting the negative electrode terminal 301 into the through hole, crimping the negative electrode terminal 301 on the second conductive member 440, and then welding the crimped portion to the second conductive member 440.

[0074] 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 positioned along the first sealing plate 120.

[0075] A stepped portion 435 is provided between the first planar portion 431 and the second planar portion 432. The stepped portion 435 causes the positions of the first planar portion 431 and the second planar portion 432 in the first direction (X direction) to differ when the secondary battery 1 is assembled. This allows the first planar portion 431 and the second planar portion 432 to be arranged side by side in one direction. The stepped portion 435 extends along the third direction (Z direction).

[0076] A first insulating member 510 (resin material) is placed between the negative terminal 301 and the first sealing plate 120. A second insulating member 520 (resin material) is placed between the first sealing plate 120 and the first conductive member 430 and the second conductive member 440. Note that the first insulating member 510 and the second insulating member 520 may be a single integrated component.

[0077] The negative electrode terminal 301 is attached to the first sealing plate 120 via the first insulating member 510. The negative electrode terminal 301 is exposed on the outside of the first sealing plate 120 and is positioned to reach the second conductive member 440 of the negative electrode current collector 410, which is provided on the inner surface side of the first sealing plate 120.

[0078] The assembly procedure for each component 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, which is electrically connected to the electrode body 200, is attached to the second conductive member 440. At this time, the first conductive member 430 is positioned on the first insulating member 510 such that a part of the first conductive member 430 overlaps with the second conductive member 440. Subsequently, the first conductive member 430 and the second conductive member 440 are welded together at the joint 434.

[0079] However, the negative terminal 301 may be electrically connected to the first sealing plate 120. Alternatively, the first sealing plate 120 may also function as the negative terminal 301.

[0080] In Figures 14 and 15, a negative electrode current collector 410 consisting of two parts (a first conductive member 430 and a second conductive member 440) is shown as an example, but the negative electrode current collector 410 may also be composed of a single part.

[0081] Figures 14 and 15 show the connection structure on the negative electrode side, but the basic connection structure on the positive electrode side is the same as that on the negative electrode side.

[0082] (Insertion process of electrode body 200) Figure 16 shows the process of inserting the electrode body 200 into the case body 110. As shown in Figure 16, a resin insulating sheet 700 (electrode body holder) is placed between the electrode body 200 and the case body 110.

[0083] The insulating sheet 700 may be made of, for example, a 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).

[0084] The insulating sheet 700 does not necessarily need to cover the entire surface of the electrode body 200. Preferably, the insulating sheet 700 covers an area of ​​50% or more, more preferably 70% or more, of the outer surface of the electrode body. Preferably, the insulating sheet 700 covers the entirety of four of the six surfaces of the substantially rectangular parallelepiped (flat-shaped) electrode body 200, excluding the two surfaces on which the negative electrode tab group 220 and the positive electrode tab group 250 are formed, respectively.

[0085] Figure 17 shows the process of placing the first spacer 600 between the first sealing plate 120 and the electrode body 200.

[0086] As shown in Figure 17, the group of negative electrode tabs 220, which are positioned from the electrode body 200 toward the first sealing plate 120, are curved so as to bend from the center in the Y direction toward the edge of the first sealing plate 120, and then fold back toward the center. A first spacer 600 is provided to accommodate the curved portion of the group of negative electrode tabs 220. The first spacer 600 is positioned between the electrode body 200 and the first sealing plate 120.

[0087] The first spacer 600 includes a first component 610 and a second component 620. The first component 610 and the second component 620 engage with each other by engaging portions 630A and 630B by sliding them along the Y-direction from the end side to the center side of the first sealing plate 120, respectively. This fixes the first spacer 600 to the first sealing plate 120 via the second insulating member 520, increasing the stability of the position of the first spacer 600.

[0088] The secondary battery 1 according to this embodiment includes a second spacer (not shown). The second spacer is positioned between the electrode body and the second sealing plate. The second spacer may have the same structure as the first spacer 600. The first spacer 600 and the second spacer may also have different shapes.

[0089] (Case body 110 fabrication) Figure 18 shows the plate-shaped member 110A that constitutes the case body 110. Figure 19 shows the plate-shaped member 110A in a bent state.

[0090] As shown in Figure 18, the plate-like member 110A is bent along the bent portion 110B. This forms a cylindrical shape having a pair of second side portions 112, as shown in Figure 19. Here, the joint portion 115 is formed where the two ends 110C parallel to the bent portion 110B meet. Alternatively, the vicinity of the two ends 110C may be joined by overlapping them in the thickness direction of the plate-like member 110A.

[0091] In a pair of second side portions 112, a gas discharge valve 150 is provided on the upper portion 112A, and a joint portion 115 is provided on the bottom portion 112B. The gas discharge valve 150 is formed by a thin-walled portion or groove provided on the upper portion 112A of the case body 110. The gas discharge valve 150 can be formed by press working or cutting. It is preferable to form the gas discharge valve 150 by press working. When the gas discharge valve 150 is formed by press working, the shape of the thin-walled portion or groove is stable, so a more stable crack strength of the gas discharge valve 150 can be obtained.

[0092] Alternatively, a gas exhaust valve can be provided in the case body by joining a component that includes the gas exhaust valve portion to the case body. For example, a through hole can be provided in the case body, a component including the gas exhaust valve portion can be placed to close the through hole, and the component and the case body can be joined by welding or other means.

[0093] The gas discharge valve 150 may be formed in the state of the plate-shaped member 110A shown in Figure 18 (flat state before bending), or in the state shown in Figure 19 (cylindrical state after bending), or part or all of its processing may be carried out simultaneously with the bending process of the plate-shaped member 110A.

[0094] When the gas exhaust valve 150 is formed in the state of the plate-shaped member 110A before bending, it is possible to more effectively suppress deformation of the case body 110 due to the strain of the processing that forms the gas exhaust valve 150.

[0095] Furthermore, if the gas discharge valve 150 is formed in the state after bending, deformation of the gas discharge valve 150 due to bending can be effectively suppressed.

[0096] (Construction of insulating sheet 700) Figure 20 shows an example of the arrangement of the electrode body 200 and insulating sheet 700 inside the case body 110.

[0097] As shown in Figure 20, the insulating sheet 700 is provided so as to cover the outer circumference of the electrode body 200. In some cases, the insulating sheet 700 may leave a portion of the electrode body 200 exposed.

[0098] The insulating sheet includes a first end 701 and a second end 702 extending in the X direction. Here, one end of one insulating sheet 700 is the first end 701, and the other end of one insulating sheet 700 is the second end 702. In the example shown in Figure 20, the first end 701 and the second end 702 are positioned opposite the upper surface 112A of the case body 110. An overlapping region 710 is provided between the first end 701 and the second end 702, where two insulating sheets 700 are stacked on top of each other.

[0099] In this way, by positioning the first end 701 and the second end 702 of the insulating sheet 700 so as to face the upper surface portion 112A on which the gas discharge valve 150 is provided, the gas generated in the electrode body 200 can easily move from the gap in the overlapping region 710 toward the gas discharge valve 150.

[0100] It is preferable that the insulating sheet 700 is not completely bonded or welded in the overlapping region 710. This allows for the stable formation of the gas discharge path described above. The cylindrical shape of the insulating sheet 700 can be stably maintained by bonding or welding the overlapping insulating sheets 700 to each other at multiple spaced locations in the overlapping region 710.

[0101] Figure 21 is an unfolded view of the insulating sheet 700. As shown in Figure 21, the insulating sheet 700 is formed into a cylindrical shape by folding the sheet material 700A along the folding portion 700B.

[0102] Figure 22 is a front view showing the electrode body 200 and the insulating sheet 700. As shown in Figure 22, it is preferable that the insulating sheet 700 is provided so as to cover the entire main body portion 270 of the electrode body 200 (excluding the negative electrode tab group 220 and the positive electrode tab group 250) and the base portions of the negative electrode tab group 220 and the positive electrode tab group 250. That is, the width of the insulating sheet 700 in the X direction is greater than the width of the main body portion 270 of the electrode body 200 in the X direction.

[0103] In this way, damage to the electrode body 200 can be suppressed more effectively. Furthermore, as shown in Figure 20, by providing the overlapping region 710 of the insulating sheet 700 on the gas discharge valve 150 side, the gas escape from the inner circumference of the insulating sheet 700 toward the gas discharge valve 150 is improved, making it possible to operate the gas discharge valve 150 more stably.

[0104] Figure 23 shows a modified example of the arrangement of the electrode body and separator inside the case body 110. In the example shown in Figure 23, the overlapping region 710 of the insulating sheet 700 is located in a region that does not overlap with the gas exhaust valve 150 when viewed from the Z direction (a region shifted in the Y direction).

[0105] In the example shown in Figure 23, the opening of the overlapping region 710 is close to the gas discharge valve 150, and the gas discharge path from the inner circumference of the insulating sheet 700 to the gas discharge valve 150 is further shortened. Furthermore, the overlapping region 710 is not formed directly below the gas discharge valve 150. This further improves the gas release towards the gas discharge valve 150.

[0106] However, the configuration of the insulating sheet 700 is not limited to those shown in Figures 20 to 23. Furthermore, the insulating sheet 700 is not necessarily an essential component in this technology.

[0107] (Arrangement of gas exhaust valve 150) Figure 24 shows the upper part of the electrode body 200. As shown in Figure 24, the two electrode bodies 201 and 202 contained within the electrode body 200 are both wound-type electrode bodies. The electrode bodies 201 and 202 are adjacent to each other. Electrode body 201 (first electrode body) includes a curved surface 201A (first curved surface) facing the upper surface 112A of the case body 110, and electrode body 202 (second electrode body) includes a curved surface 202A (second curved surface) facing the upper surface 112A of the case body 110.

[0108] As shown in Figure 24, when viewed from the X direction, the curved surfaces 201A and 202A each have a first vertex A1 and a second vertex A2 closest to the upper surface 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 called "region A", it is preferable that at least a part of the gas exhaust valve 150 (more preferably the part that becomes the starting point of the crack) is located in region A. Preferably, 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 A.

[0109] More preferably, as shown in Figure 24, when the region shifted inward by D1 / 6 from each of the first vertex A1 and the second vertex A2 is defined as "region B", at least a portion of the gas exhaust valve 150 (more preferably the portion that becomes the starting point of the crack) 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.

[0110] Figures 25 to 33 show examples of the arrangement of the gas discharge valve 150 on the upper surface portion 112A of the case body 110. In Figures 25 to 33, the dashed lines correspond to the diagonals of the rectangular upper surface portion 112A.

[0111] The ratio of the length of the short side to the long side of the rectangular upper surface portion 112A on which the gas discharge valve 150 is provided is preferably about 1:6 to 1:30.

[0112] In the example shown in Figure 25, the gas exhaust valve 150 includes a first portion 151 extending in the X direction (longitudinal direction) and a second portion 152 extending in the Y direction (short direction). The first portion 151 and the second portion 152 intersect at the center of the upper surface portion 112A (the intersection of the diagonals).

[0113] When the length of the case body 110 in the X direction is L1 and the length of the first part 151 of the gas discharge valve 150 is L2, it is preferable that L2 / L1 is greater than 0.5, and more preferably greater than 0.6.

[0114] This allows for a relatively large opening area of ​​the gas discharge valve 150, enabling more effective gas discharge when the gas discharge valve 150 ruptures. It is preferable that the rupture occurs over a length of approximately 2 / 3 L1 or more when the gas discharge valve 150 opens.

[0115] Furthermore, by providing a second portion 152 that intersects (orthogonally) with the first portion 151, the second portion 152 can also be fractured in addition to the first portion 151, thereby further increasing the opening area of ​​the gas discharge valve 150.

[0116] It is possible to vary the remaining thickness of the groove (thin-walled portion) that constitutes the gas discharge valve 150 depending on its position. For example, the remaining thickness can be made relatively thinner (the groove can be made deeper) around the intersection of the first portion 151 and the second portion 152. Along the diagonal of the upper surface portion 112A, a relatively large stress is generated when the internal pressure of the case 100 increases, and a relatively large deformation occurs in that portion. By providing a portion with a thin remaining thickness along the diagonal of the upper surface portion 112A, the portion with large deformation (high stress) can be made thinner, that is, the stress concentration portion and the strength-weak portion can be made to coincide, thereby stabilizing the fracture location and fracture strength of the gas discharge valve 150. As a result, it is possible to stabilize the operating pressure of the gas discharge valve 150 and improve the reliability of the gas discharge valve 150.

[0117] In the example shown in Figures 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 Figures 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 other ends of the first portion 151 in the X direction. Furthermore, the shape of the two second portions 152 is not limited to those illustrated in Figures 26 and 27.

[0118] In the example shown in Figure 28, the gas discharge valve 150 is arranged in a roughly X-shape along the diagonal of the upper surface portion 112A.

[0119] In the example shown in Figure 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 (long direction). In the example in Figure 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 the first portion 151 in places other than both ends in the Y direction.

[0120] In the examples shown in Figures 30 to 33, the gas exhaust valve 150 is arranged in multiple regions that are spaced apart from each other. In the examples in Figures 30 to 33, two separate gas exhaust valves 150 are arranged so that each reaches the end of the upper surface portion 112A in the X direction. The gas exhaust valve may be arranged in three or more regions.

[0121] In the example in Figure 30, the two gas exhaust valves 150 are each formed linearly so as to extend in the X direction (longitudinal direction), while in the examples in Figures 31 and 33, the two gas exhaust valves 150 are each formed in a roughly cross shape. In the example in Figure 32, the two gas exhaust valves 150 are each formed in a roughly U shape so as to open toward the end in the X direction.

[0122] In the example shown in Figure 33, the gas exhaust valve 150 is located inside a recess 160 (thin-walled region) formed in the upper surface portion 112A. Figure 34 is a cross-sectional view taken along line XXXIV-XXXIV in Figure 33. As shown in Figure 34, the recess 160 is formed such that the thickness of the case body 110 is relatively small, so the amount of deformation when the internal pressure of the case 100 increases is relatively large. Therefore, by forming the gas exhaust valve 150 inside the recess 160, the gas exhaust valve 150 can be operated more stably when the internal pressure of the case 100 increases.

[0123] The length of each gas discharge valve 150 is preferably about 1 / 15 or more of the length L1 of the case body 110 (Figure 25), more preferably about 1 / 8 or more, and even more preferably about 1 / 5 or more.

[0124] The arrangement of the gas discharge valve 150 is not limited to those shown in Figures 25 to 34. Furthermore, it is possible to use a combination of the configurations illustrated in Figures 25 to 34.

[0125] Figure 35 is an enlarged cross-sectional view showing an example of a groove portion constituting the gas exhaust valve 150. As shown in Figure 35, the groove portion constituting the gas exhaust 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.

[0126] By forming the grooves that constitute the gas discharge valve 150 on the outer surface of the case body 110, it is possible to suppress the electrode body 200 from getting caught (interfering) with the grooves when inserting the electrode body 200 into the case body 110. On the other hand, if the grooves are formed on the inner surface of the case body 110, the surface of the grooves is protected after inserting the electrode body 200 into the case body 110 and sealing it with the first sealing plate 120 and the second sealing plate 130, thereby making the operating pressure of the gas discharge valve 150 more stable.

[0127] In the example shown in Figure 35, the gas exhaust valve 150 is composed of a roughly V-shaped groove. In this example, the opening angle θ of the roughly V-shape is approximately 60° to 90°. However, the shape of the groove that constitutes the gas exhaust valve 150 is not limited to that shown in Figure 35; for example, the gas exhaust valve 150 may be composed of a groove with a roughly rectangular cross-sectional shape.

[0128] Figure 36 is a diagram illustrating the arrangement of the gas exhaust valve 150 in the X direction (first direction).

[0129] As shown in Figure 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 toward the first sealing plate 120 side and the second sealing plate 130 side, respectively.

[0130] 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 discharge valve 150 is positioned to reach the end regions R120 and R130.

[0131] In one example, the length of the end regions R120 and R130 in the X direction is approximately 12 mm ± 1 mm each. The length of the end regions R120 and R130 is, for example, less than 1 / 5 of the length L1 of the case body 110.

[0132] The gas discharge valve 150 is formed to extend outward (towards the first sealing plate 120 and the second sealing plate 130) by a length of, for example, 50 percent or more of the length of the end regions R120 and R130, from the boundary between region R270 and end regions R120 and R130.

[0133] In this way, by positioning the gas discharge valve 150 so that it reaches the end regions R120 and R130 located at both ends in the X direction, when the internal pressure of the case 100 rises, gas can be flowed to the gas discharge valve 150 through the gaps on the negative electrode tab group 220 and the positive electrode tab group 250, allowing the gas discharge valve 150 to rupture more smoothly and the gas to be discharged.

[0134] (Effects and Benefits) According to this embodiment of the secondary battery 1, by inserting the electrode body 200 into a case body 110 having a first opening 113 and a second opening 114 facing each other, and sealing the first opening 113 and the second opening 114 respectively, the height of the secondary battery 1 can be reduced, resulting in a secondary battery 1 that is high capacity and easily mountable in a vehicle.

[0135] Furthermore, by providing a gas exhaust valve 150 on the upper surface 112A of the case body 110 and a joint 115 on the bottom surface 112B opposite the upper surface 112A, the gas exhaust valve 150 and the joint 115 are spaced apart on different sides of the case body 110, which stabilizes the operating pressure of the gas exhaust valve 150. As a result, a high-capacity and highly reliable secondary battery 1 can be provided.

[0136] Alternatively, a gas discharge valve 150 may be provided on the bottom surface 112B of the case body 110, and a joint 115 may be provided on the top surface 112A facing the bottom surface 112B.

[0137] Furthermore, as shown in Figures 20 and 23, by positioning the overlapping region 710 of the insulating sheet 700 opposite the upper surface portion 112A on which the gas discharge valve 150 is provided, the gas generated inside the electrode body 200 can be smoothly directed toward the gas discharge valve 150.

[0138] Furthermore, as shown in Figure 24, by positioning at least a portion of the gas discharge valve 150 in region A or region B located between the first vertex A1 and the second vertex A2 of a plurality of adjacent electrode bodies 201, 202, the gas generated inside the electrode body 200 can be smoothly directed toward the gas discharge valve 150. Therefore, the operating pressure of the gas discharge valve 150 can be further stabilized.

[0139] In this embodiment, an example was described in which the centers of the negative electrode tab group 220 and the positive electrode tab group 250 are located near the center of the electrode body 200 in the Z direction. However, the centers of the negative electrode tab group 220 and the positive electrode tab group 250 may also be positioned on the opposite side of the gas discharge valve 150 (upper surface portion 112A), that is, on the lower side in the Z direction (bottom surface portion 112B side). Doing so makes it easier to secure a gas discharge path to the gas discharge valve 150.

[0140] In the example shown in Figure 2, the joint 115 is located at the center of the bottom portion 112B in the Y direction. In the Y direction, the joint 115 can be positioned offset from the center of the bottom portion 112B towards either end (one of the two long ends of the bottom portion 112B). In such a case, even if the internal pressure inside the case 100 increases, damage to the joint 115 can be more reliably suppressed by shifting the joint 115 away from areas where stress tends to concentrate. Therefore, the gas discharge valve 150 operates more stably. In particular, it is preferable that the portion of the joint 115 located at the center of the bottom portion 112B in the X direction has such a configuration.

[0141] While embodiments of the present technology have been described above, the embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present technology is defined by the claims, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of symbols]

[0142] 1 Secondary battery, 100 Case, 110 Case body, 110A Plate-shaped member, 110B Bent part, 110C Edge, 111 First side part, 112 Second side part, 112A Top part, 112B Bottom part, 113 First opening, 114 Second opening, 115 Joint part, 120 First sealing plate, 121 Injection hole, 130 Second sealing plate, 131 Injection hole, 150 Gas discharge valve, 151 First part, 152 Second part, 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 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, 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 section, 432; Second flat section, 433, 434; Joint section, 435; Step section, 440; Second conductive member, 441; Joint section, 454; Joint section, 510; First insulating member, 520; Second insulating member, 600; First spacer, 610; First component, 620; Second component, 630A, 630B; Engaging section, 700; Insulating sheet, 700A Sheet material, 700B folded portion, 701 first edge, 702 second edge, 710 overlapping region.

Claims

1. An electrode body comprising a first electrode and a second electrode having a polarity different from that of the first electrode, The system comprises a case for housing the electrode body, The aforementioned case is, A case body having a first opening located at the end of the first side in the first direction, and a second opening located at the end of the second side opposite to the first side in the first direction, A first sealing plate that seals the first opening, The second opening is sealed by a second sealing plate, 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 facing each other in a third direction perpendicular to the first and second directions, wherein the area of ​​the pair of first walls is larger than the area of ​​the pair of second walls. A gas discharge valve is provided on one of the pair of second walls, which ruptures when the pressure inside the case exceeds a predetermined value. A joint extending in the first direction is provided on the other of the pair of second walls. The electrode body includes a first electrode body and a second electrode body, and 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 the pair of second walls, and the first curved surface has 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, and the second curved surface has a second vertex closest to one of the pair of second walls. At least a portion of the gas exhaust valve is positioned in the region located between the first vertex and the second vertex in the second direction. The first electrode body and the second electrode body each have a first electrode tab connected to the first electrode at the end on the first sealing plate side, The first electrode body and the second electrode body each have a second electrode tab connected to the second electrode at the end on the second sealing plate side, The length of the first wall in the first direction is 30 cm or more. A secondary battery in which the length of the first wall in the third direction is 20 cm or less.

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

3. The first electrode tab is electrically connected to the first electrode terminal provided on the first sealing plate. The secondary battery according to claim 1 or claim 2, wherein the second electrode tab is electrically connected to a second electrode terminal provided on the second sealing plate.

4. At least a portion of the gas discharge valve is positioned in the first end region of the first electrode body, which is closer to the first opening than the main body of the first electrode body, The secondary battery according to claim 1 or claim 2, wherein at least a portion of the gas discharge valve is positioned in the second end region, which is closer to the second opening than the main body portion of the first electrode body in the first direction.

5. The secondary battery according to claim 1 or claim 2, wherein the gas discharge valve is divided into a plurality of regions spaced apart from each other on one of the pair of second walls.

6. A thin-walled region is formed on one of the pair of second walls, where the thickness of the case body is relatively small. The secondary battery according to claim 1 or claim 2, wherein the gas discharge valve is disposed inside the thin-walled region.

7. The secondary battery according to claim 1 or claim 2, wherein in the second direction, the joint is positioned at a location offset from the center of the other of the pair of second walls toward either end.

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