Rectangular rechargeable battery

Abstract

To provide a prismatic secondary battery including a highly reliable gas exhaust valve.SOLUTION: In a prismatic secondary battery, a positive electrode terminal electrically connected to a positive electrode tab is provided on a third wall, of a pair of third walls, facing the positive electrode tab; a negative electrode terminal electrically connected to a negative electrode tab is provided on a third wall, of the pair of third walls, facing the negative electrode tab; at least one of a pair of second walls includes a base portion and a protruding portion protruding from the base portion in a direction away from a first end surface of an electrode body; and the protruding portion is provided with a gas exhaust valve that is fractured when pressure in a case becomes a predetermined value or more.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] This technology relates to a rectangular secondary battery.

Background Art

[0002] Japanese Unexamined Patent Application Publication No. 2021-89812 (Patent Document 1), Japanese Unexamined Patent Application Publication No. 2019-133854 (Patent Document 2), and Japanese Unexamined Patent Application Publication No. 2022-149950 (Patent Document 3) disclose rectangular secondary batteries provided with a gas discharge valve that breaks when the pressure inside the case reaches a predetermined value or more.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] From the perspective of the reliability of the gas discharge valve, there is still room for improvement in the rectangular secondary batteries described in Patent Documents 1 to 3.

[0005] An object of this technology is to provide a rectangular secondary battery provided with a highly reliable gas discharge valve.

Means for Solving the Problems

[0006] This technology provides the following rectangular secondary battery.

[0007] [1] A prismatic secondary battery comprising an electrode body including a positive electrode and a negative electrode, and a case housing the electrode body, the case comprising a pair of opposing first walls, a pair of opposing second walls, and a pair of opposing third walls, the electrode body having a positive electrode tab electrically connected to the positive electrode on a surface facing one of the pair of third walls, the electrode body having a negative electrode tab electrically connected to the negative electrode on a surface facing either of the pair of third walls, a positive electrode terminal electrically connected to the positive electrode tab provided on the third wall of the pair of third walls facing the positive electrode tab, and a negative electrode terminal electrically connected to the negative electrode tab provided on the third wall of the pair of third walls facing the negative electrode tab, and at least one of the pair of second walls comprising a base portion and a projection protruding from the base portion in a direction away from the first end face of the electrode body, and a gas release valve that ruptures when the pressure inside the case exceeds a predetermined value is provided on the projection.

[0008] [2] The prismatic secondary battery according to [1], wherein at least one of a pair of third walls is connected to a portion of the second wall having a projection.

[0009] [3] The prismatic secondary battery according to [2], wherein the electrode body has a second end face on which at least one of a positive electrode tab and a negative electrode tab is provided, a first space is formed between the protrusion and the first end face of the electrode body, a second space is formed between the third wall and the second end face of the electrode body, and the first space and the second space are in communication.

[0010] [4] A prismatic secondary battery according to any one of [1] to [3], further comprising an insulating sheet disposed between a protrusion and the first end face of the electrode body, wherein the insulating sheet is positioned closer to the first end face of the electrode body than to the inner surface of the protrusion.

[0011] [5] A prismatic secondary battery according to any one of [1] to [4], wherein the projection includes a first projection included in one of a pair of second walls and a second projection included in the other of the pair of second walls, and the gas exhaust valve includes a first gas exhaust valve provided in the first projection and a second gas exhaust valve provided in the second projection. [Effects of the Invention]

[0012] According to the present technology, by providing a gas discharge valve in a protruding portion that protrudes in a direction away from the first end face of the electrode body, a stable discharge path through which high-temperature gas or the like generated inside the case reaches the gas discharge valve can be ensured. As a result, a rectangular secondary battery provided with a highly reliable gas discharge valve can be provided.

Brief Description of the Drawings

[0013] [Figure 1] It is a front view showing the configuration of the secondary battery according to Embodiment 1. [Figure 2] It is a view showing the state of the secondary battery shown in FIG. 1 as viewed from the direction of arrow II. [Figure 3] It is a view showing the state of the secondary battery shown in FIG. 1 as viewed from the direction of arrow III. [Figure 4] It is a view showing the state of the secondary battery shown in FIG. 1 as viewed from the direction of arrow IV. [Figure 5] It is a front cross-sectional view of the secondary battery shown in FIG. 1. [Figure 6] It is a front view showing the negative electrode raw sheet before the negative electrode plate is formed. [Figure 7] It is a VII-VII cross-sectional view of the negative electrode raw sheet shown in FIG. 6. [Figure 8] It is a front view showing the negative electrode plate formed from the negative electrode raw sheet. [Figure 9] It is a front view showing the positive electrode raw sheet before the positive electrode plate is formed. [Figure 10] It is an X-X cross-sectional view of the positive electrode raw sheet shown in FIG. 9. [Figure 11] It is a front view showing the positive electrode plate formed from the positive electrode raw sheet. [Figure 12] It is a view showing the electrode body and the current collector taken out from the secondary battery. [Figure 13] It is a front view of the connection structure between the negative electrode tab group and the negative electrode current collector. [Figure 14] It is a cross-sectional view of the connection structure between the negative electrode tab group and the negative electrode current collector. [Figure 15] It is a perspective view showing the electrode body. [Figure 16]This is a magnified view of the area near the top surface of the wound electrode body. [Figure 17] This is an enlarged cross-sectional view showing an example of the shape of the protruding part. [Figure 18] This is an enlarged cross-sectional view showing a variation in the shape of the protruding part. [Figure 19] This is a front cross-sectional view of a secondary battery according to Embodiment 2. [Figure 20] This is a diagram illustrating the first and second spaces in a secondary battery according to Embodiment 1. [Figure 21] This is a diagram illustrating the first and second spaces in a secondary battery according to Embodiment 2. [Figure 22] This is a perspective view showing a battery pack formed by stacking secondary batteries according to Embodiment 1. [Figure 23] This is a diagram (part 1) showing an example of the arrangement of the protruding part and the gas discharge valve. [Figure 24] This is a diagram (part 2) showing an example of the arrangement of the protruding part and the gas discharge valve. [Figure 25] This is a diagram (part 3) showing an example of the arrangement of the protruding part and the gas discharge valve. [Figure 26] This is Figure (4) showing an example of the arrangement of the protruding part and the gas discharge valve. [Figure 27] This is Figure (5) showing an example of the arrangement of the protruding part and the gas discharge valve. [Modes for carrying out the invention]

[0014] 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.

[0015] 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.

[0016] 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.

[0017] 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).

[0018] 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.

[0019] In order to facilitate understanding of the invention, some of the dimensions of the components in the drawings have been altered from the actual dimensions.

[0020] (Embodiment 1) Figure 1 is a front view of the secondary battery 1 according to Embodiment 1. 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 5 is a front cross-sectional view of the secondary battery 1 shown in Figure 1.

[0021] 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.

[0022] In Figures 1 to 18 relating to Embodiment 1, the direction along the winding axis of the electrode body of the secondary battery 1 is defined as the X direction as the first direction, the Y direction as the second direction is 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 as the third direction is the direction perpendicular to the first direction and the long side of the electrode body as viewed from the first direction.

[0023] In this embodiment, 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.

[0024] As shown in Figures 1 to 5, 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, a second sealing plate 130, a protrusion 140, and a gas discharge valve 150.

[0025] The case body 110 consists of a cylindrical, more specifically, rectangular cylindrical component. 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] The first sealing plate 120 and the second sealing plate 130 (third wall) 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] As shown in Figure 5, 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.

[0042] Specifically, one or more wound electrode bodies are housed inside an insulating sheet placed within the case 100, along with an electrolyte solution (not shown). The insulating sheet is positioned closer to the lower surface 271B (described later) of the electrode body 200 than to the inner surface of the protrusion 140 of the case 100. The "insulating sheet" referred to here is formed separately from the separator that constitutes the electrode body 200. In this technology, "opposing" includes, for example, opposition via the "insulating sheet". However, the "insulating sheet" is not an essential component in this technology.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] The bottom portion 112B of the case body 110 has a base portion 112B0 formed in the center in the X direction so as to be aligned with the electrode body 200, and protrusions 140 are formed on both sides (both ends in the X direction) so as to protrude away from the electrode body 200.

[0051] The shortest distance (gap) in the Z direction between the inner surface of the base portion 112B0 and the lower surface 271B (described later) of the electrode body 200 is preferably 5 mm or less, more preferably 3 mm or less, and even more preferably 1 mm or less.

[0052] The protruding height of the protruding portion 140 (the distance in the Z direction between the inner surface of the base portion 112B0 and the inner surface of the protruding portion 140) is preferably about 1 mm or more, and more preferably about 3 mm or more.

[0053] A gas discharge valve 150 is provided on the protruding portion 140. The gas discharge valve 150 is formed on the bottom portion 112B of the wound electrode body 200, spaced apart from the winding axis. The gas discharge valve 150 ruptures when the pressure inside the case 100 exceeds a predetermined value. The gas discharge valve 150 can be formed by providing a thin-walled portion or a grooved portion on the protruding portion 140.

[0054] Figure 6 is a front view showing the negative electrode base plate 210S before the negative electrode plate 210 (first electrode) is formed, Figure 7 is a VII-VII cross-sectional view of the negative electrode base plate 210S shown in Figure 6, and Figure 8 is a front view showing the negative electrode plate 210 formed from the negative electrode base plate 210S.

[0055] The negative electrode plate 210 is manufactured by processing the negative electrode base plate 210S. As shown in Figures 6 and 7, 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] As shown in Figure 8, 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 illustrated in Figure 8.

[0060] Figure 9 is a front view showing the positive electrode base plate 240S before the positive electrode plate 240 (second electrode) is formed, Figure 10 is a cross-sectional view of the positive electrode base plate 240S shown in Figure 9, and Figure 11 is a front view showing the positive electrode plate 240 formed from the positive electrode base plate 240S.

[0061] 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 9 and 10, the positive electrode base plate 240S includes a positive electrode core 241, a positive electrode active material layer 242, and a positive electrode protective layer 243. The positive electrode core 241 is aluminum foil or aluminum alloy foil.

[0062] 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.

[0063] The positive electrode active material layer slurry is prepared by kneading lithium nickel cobalt manganese composite oxide as the positive electrode active material, polyvinylidene fluoride (PVdF) as a binder, 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] As shown in Figure 11, 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 shown in Figure 11.

[0068] A positive electrode protective layer 243 is provided at the base of each of the multiple positive electrode tabs 260. However, a positive electrode protective layer 243 is not necessarily provided at the base of each positive electrode tab 260.

[0069] 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.

[0070] Figure 12 shows the electrode body 200 and current collector 400 taken from the secondary battery 1. As shown in Figure 12, 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 12, 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.

[0071] 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.

[0072] Figure 13 is a front view of the connection structure between the negative electrode tab group and the negative electrode current collector. Figure 14 is a cross-sectional view of the connection structure between the negative electrode tab group and the negative electrode current collector.

[0073] As shown in Figures 13 and 14, 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.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] 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).

[0079] 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.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] In Figures 13 and 14, 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.

[0084] Figures 13 and 14 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.

[0085] Figure 15 is a perspective view showing the electrode body 200. As shown in Figure 15, the main body of the electrode body 200 has an upper surface 271A and a lower surface 271B (first end surface), short sides 272A and 272B (second end surface), and long sides 273A and 273B (third end surface). The upper surface 271A and the lower surface 271B face the first side surface 111 of the case body 110, respectively. The short sides 272A and 272B face the first sealing plate 120 and the second sealing plate 130, respectively. The long sides 273A and 273B face the second side surface 112 of the case body 110, respectively.

[0086] Figure 16 is an enlarged view of the area around the upper surface 271A of the electrode body 200. As shown in Figure 16, when the wound electrode bodies 201 and 202 are stacked to form the electrode body 200, the curved surfaces 201A and 202A of each electrode body 201 and 202 are combined to form the upper surface 271A of the electrode body 200.

[0087] According to the shape of the upper surface 271A shown in Figure 16, the cavity located between the curved surfaces 201A and 202A can be used as a gas passage within the case 100.

[0088] Although the shape of the lower surface 271B is not shown in the figure, it can be made to be the same shape as the upper surface 271A shown in Figure 16.

[0089] Figure 17 is an enlarged cross-sectional view showing the shape of the protrusion 140. Figure 18 is an enlarged cross-sectional view showing a modified example of the shape of the protrusion 140.

[0090] In the example shown in Figure 17, the first sealing plate 120 (third wall) and the portion of the bottom surface 112B (second wall) of the case body 110 where the protrusion 140 is provided are connected. In the example shown in Figure 18, the first sealing plate 120 (third wall) and the portion of the bottom surface 112B (second wall) of the case body 110 where the protrusion 140 is provided are separated in the X direction.

[0091] In both the example shown in Figure 17 and Figure 18, the space formed between the protrusion 140 and the lower surface 271B (first end face) of the electrode body 200 (first space) is in communication with the space formed between the first sealing plate 120 and the short side surface 272A (second end face) of the electrode body 200 (second space).

[0092] In this way, a stable discharge path to the gas discharge valve 150 can be secured within the case 100. Specifically, the gas discharged from the short side 272A of the wound electrode body 200 to the outside of the electrode body 200 is guided into the space formed inside the protrusion 140, and can be discharged to the outside of the case 100 via the gas discharge valve 150 formed in the protrusion 140. However, in this technology, the two spaces (first space and second space) do not necessarily have to be in direct communication.

[0093] (Embodiment 2) Figure 19 is a front cross-sectional view of a secondary battery 10 according to Embodiment 2. As shown in Figure 19, the secondary battery 10 includes a case 1000, an electrode body 2000, electrode terminals 3000, and a current collector 4000.

[0094] The case 1000 includes a bottomed case body including side portions 1100 and a bottom portion 1300, a sealing plate 1200, a protruding portion 1400, and a gas discharge valve 1500.

[0095] The electrode body 2000 has a pair of side surfaces 2710 (first end faces) and an upper surface 2720 (second end face). The upper surface 2720 is provided with a negative electrode tab group 2200 and a positive electrode tab group 2500. The electrode body 2000 is a wound-type electrode body in which a positive electrode plate and a negative electrode plate are wound around a winding axis extending in the vertical direction in Figure 19. However, the electrode body 2000 may be a laminated-type electrode body.

[0096] The negative electrode tab group 2200 is electrically connected to the negative electrode terminal 3010 via the negative electrode current collector 4100. The positive electrode tab group 2500 is electrically connected to the positive electrode terminal 3020 via the positive electrode current collector 4200.

[0097] The side surface 2710 of the electrode body 2000 includes side surfaces 2710A and 2710B formed on both the left and right sides in the figure, respectively. The projection 1400 includes a left projection 1400 (first projection) located opposite side surface 2710A of the electrode body 2000, and a right projection 1400 (second projection) located opposite side surface 2710B of the electrode body 2000. The gas discharge valve 1500 includes a left gas discharge valve 1500 (first gas discharge valve) located on the left projection 1400, and a right gas discharge valve 1500 (second gas discharge valve) located on the right projection 1400. In other words, in this embodiment, both gas discharge valves 1500 are formed on side surfaces 1100 spaced apart from the winding axis of the wound electrode body 2000.

[0098] However, the protrusions 1400 and gas discharge valves 1500 are not limited to being formed on both the left and right sides, and the protrusions 1400 and gas discharge valves 1500 may be provided only on one side portion 1100.

[0099] Other matters are the same as in Embodiment 1, so a detailed explanation will not be repeated.

[0100] (First space and second space) Figures 20 and 21 are diagrams illustrating the internal space of the secondary batteries 1 and 10 according to Embodiment 1 and Embodiment 2, respectively. The dashed lines in Figures 20 and 21 represent imaginary straight lines extending in the direction of the extension of the inner surface of the base portion.

[0101] In the example shown in Figure 20 (Embodiment 1), a first space 11 is formed between the protruding portion 140 and the electrode body 200, and a second space 12 is formed between the first sealing plate 120 (third wall) and the electrode body 200.

[0102] In the example shown in Figure 21 (Embodiment 2), a first space 11 is formed between the protruding portion 1400 and the electrode body 200, and a second space 12 is formed between the sealing plate 1200 (third wall) and the electrode body 200.

[0103] In the example in Figure 20, the width of the second space 12, i.e., the distance between the short side 272A of the electrode body 200 and the first sealing plate 120, is preferably about 5 mm or more, and more preferably about 8 mm or more. In the example in Figure 21, the width of the second space 12, i.e., the distance between the upper surface 2720 of the electrode body 2000 and the sealing plate 1200, is preferably about 5 mm or more, and more preferably about 8 mm or more.

[0104] In the examples in Figures 20 and 21, the length L of the protrusions 140 and 1400. 140 ,L 1400 These are, for example, about 1 / 10 or more of the total length of case 100 and 1000 in the same direction.

[0105] Furthermore, in the examples in Figures 20 and 21, the volume of the first space 11 is 120 mm³. 3 Approximately (more preferably 200 mm) 3 Approximately the above, more preferably 300 mm 3 Approximately the above, more preferably 400 mm 3 It is preferable that the volume of the first space 11 relative to the internal volume of case 100,100 is approximately 0.05 percent or more. Furthermore, the volume of the second space 12 is 1100 mm³. 3It is preferable that the volume is approximately as described above, and that the ratio of the volume of the second space 12 to the internal volume of case 100 and 1000 (volume percentage) is approximately 1.5 percent or more.

[0106] Note that the internal volume of cases 100 and 100, as well as the volumes of the first space 11 and the second space 12, as referred to here, are calculated by including the portion occupied by the electrode bodies 200 and 2000 or other components as part of the volume of the space.

[0107] As illustrated in Figures 20 and 21, the first space 11 formed inside the protrusions 140 and 1400 and the second space 12 adjacent to the short side 272A or top surface 2720 of the electrode body 200 are reliably connected, making it possible to reliably secure a discharge path within the case that guides the gas ejected from the electrode body 200 to the gas discharge valve 150.

[0108] (Battery pack configuration) Figure 22 is a perspective view showing a state in which secondary batteries 1 according to Embodiment 1 are stacked to form a battery pack.

[0109] As shown in Figure 22, when a battery pack including a secondary battery 1 is constructed, multiple secondary batteries 1 are stacked in the thickness direction. End plates 2 are provided at both ends of the stacked secondary batteries 1. The battery pack can be constructed by constraining the stack of secondary batteries 1 and end plates 2 in the stacking direction (Y direction) with a restraining member 3. Both ends of the restraining member 3 are fixed to the end plates 2 by fastening members 4. Multiple secondary batteries 1 are electrically connected by bus bars 5. In Figure 22, the secondary batteries 1 in the central part in the Y direction are omitted from the illustration, but the number of stacked secondary batteries 1 can be changed as appropriate.

[0110] The duct that carries the gas discharged from the gas discharge valve 150 in the Y direction can be installed in a position that avoids the restraining member 3.

[0111] The configuration of the battery pack is not limited to that illustrated in Figure 22. For example, the battery pack may be directly supported on the side of the battery pack case without using the end plate 2, restraining member 3, and fastening member 4.

[0112] (Arrangement of the protrusion 140 and the gas discharge valve 150) Figures 23 to 27 show examples of the arrangement of the protruding portion 140 and the gas discharge valve 150 in the secondary battery 1 according to Embodiment 1.

[0113] As shown in the examples in Figures 23 to 26, a pair of protrusions 140 and a gas discharge valve 150 may be provided symmetrically on the bottom surface 112B of the case body 110, or, as shown in the example in Figure 27, one protrusion 140 extending in the longitudinal direction of the bottom surface 112B may be provided, with one gas discharge valve 150 in its center.

[0114] In any of the examples shown in Figures 23 to 27, the first space 11 formed inside the protrusion 140 and the second spaces 12 formed on both sides of the electrode body 200 are connected, making it possible to reliably secure a discharge path for gas and other substances discharged from the short side 272A of the electrode body 200 to reach the gas discharge valve 150.

[0115] The arrangement of the protrusions 140 and gas discharge valves 150 is not limited to those illustrated in Figures 23 to 27; for example, multiple gas discharge valves 150 may be arranged on a single protrusion 140. Furthermore, the shape and size of the protrusions 140 and gas discharge valves 150 can be modified as appropriate.

[0116] (Effects and Benefits) According to the secondary battery 1,10 described above, by providing gas discharge valves 150,1500 on the protruding parts 140,1400 that protrude away from the electrode bodies 200,2000, a stable discharge path can be secured for high-temperature gases generated inside the cases 100,1000 to reach the gas discharge valves. Therefore, when the internal pressure of the cases 100,1000 rises and gas discharge becomes necessary, the gas discharge valves 150,1500 can be operated stably, suppressing unintended rupture. Thus, according to the secondary battery 1,10 described above, it is possible to improve the reliability of the gas discharge valves 150,1500.

[0117] 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]

[0118] 1,10 Secondary battery, 2 End plate, 3 Restraining member, 4 Fastening member, 5 Bus bar, 11 First space, 12 Second space, 100 Case, 110 Case body, 111 First side part, 112 Second side part, 112A Top part, 112B Bottom part, 112B0 Base part, 113 First opening, 114 Second opening, 115 Joint part, 120 First sealing plate, 121 Injection hole, 130 Second sealing plate, 131 Injection hole, 140 Protrusion, 150 Gas discharge valve, 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, 271A Top surface, 271B Bottom surface, 272A, 272B Short side surface, 273A, 273B Long side surface, 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 planar section, 432 Second planar section, 433, 434, 441, 454 Joint section, 435 Stepped section, 440 Second conductive member, 510 First insulating member, 520 Second insulating member, 1000 Case, 1100 side section, 1200 sealing plate, 1300 bottom section, 1400 protrusion, 1500 gas discharge valve, 2000 electrode body, 2200 negative electrode tab group, 2500 positive electrode tab group, 2710, 2710A, 2710B side section, 2720 top section, 3000 electrode terminal, 3010 negative electrode terminal, 3020 positive electrode terminal, 4000 current collector, 4100 negative electrode current collector, 4200 positive electrode current collector.

Claims

1. An electrode body including a positive electrode and a negative electrode, The system comprises a case for housing the electrode body, The case includes a pair of first walls facing each other, a pair of second walls facing each other, and a pair of third walls facing each other. The electrode body has a positive electrode tab electrically connected to the positive electrode on a surface facing one of the pair of third walls. The electrode body has a negative electrode tab electrically connected to the negative electrode on a surface facing either of the pair of third walls. A positive electrode terminal electrically connected to the positive electrode tab is provided on the third wall of the pair of third walls that faces the positive electrode tab. A negative electrode terminal electrically connected to the negative electrode tab is provided on the third wall of the pair of third walls that faces the negative electrode tab. At least one of the pair of second walls includes a base portion and a projection that protrudes from the base portion in a direction away from the first end face of the electrode body, A gas discharge valve that ruptures when the pressure inside the case exceeds a predetermined value is provided on the protruding part. A prismatic secondary battery wherein at least one of the pair of third walls is connected to the portion of the second wall on which the protrusion is provided.

2. The electrode body has a second end face on which at least one of the positive electrode tab and the negative electrode tab is provided. A first space is formed between the protruding portion and the first end face of the electrode body. A second space is formed between the third wall and the second end face of the electrode body. The prismatic secondary battery according to claim 1, wherein the first space and the second space are in communication with each other.

3. An electrode body including a positive electrode and a negative electrode, The system comprises a case for housing the electrode body, The case includes a pair of first walls facing each other, a pair of second walls facing each other, and a pair of third walls facing each other. The electrode body has a positive electrode tab electrically connected to the positive electrode on a surface facing one of the pair of third walls, The electrode body has a negative electrode tab electrically connected to the negative electrode on the surface facing the other third wall of the pair of third walls, A positive electrode terminal electrically connected to the positive electrode tab is provided on one of the pair of third walls that faces the positive electrode tab. A negative electrode terminal electrically connected to the negative electrode tab is provided on the other third wall of the pair of third walls that faces the negative electrode tab. At least one of the pair of second walls includes a base portion and a projection that protrudes from the base portion in a direction away from the first end face of the electrode body, A gas discharge valve that ruptures when the pressure inside the case exceeds a predetermined value is provided on the protruding part. A first space is formed inside the protruding portion. A pair of second spaces are formed between one of the pair of third walls and the electrode body, and between the other of the pair of third walls and the electrode body. The pair of second spaces are in direct communication with one of the first spaces, and each is a prismatic secondary battery.

4. The facility further comprises an insulating sheet disposed between the protruding portion and the first end face of the electrode body, The prismatic secondary battery according to any one of claims 1 to 3, wherein the insulating sheet is positioned closer to the first end face of the electrode body than to the inner surface of the protrusion.

5. The protrusion includes a first protrusion included in one of the pair of second walls and a second protrusion included in the other of the pair of second walls. The prismatic secondary battery according to any one of claims 1 to 3, wherein the gas discharge valve includes a first gas discharge valve provided on the first protrusion and a second gas discharge valve provided on the second protrusion.

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