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

[0002] JP 2021-89812 A (Patent Document 1), JP 2019-133854 A (Patent Document 2), and JP 2022-149950 A (Patent Document 3) disclose rectangular secondary batteries equipped with a gas exhaust valve that ruptures when the pressure inside the case reaches or exceeds a predetermined value. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-89812 [Patent Document 2] JP 2019-133854 A [Patent Document 3] Patent Publication No. 2022-149950 Summary of the Invention [Problem to be solved by the invention]

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

[0005] An object of the present technology is to provide a prismatic secondary battery equipped with a highly reliable gas release valve. [Means for solving the problem]

[0006] The present technology provides the following prismatic secondary battery.

[0007] [1] A rectangular secondary battery comprising: an electrode body including a positive electrode and a negative electrode; and a case that accommodates the electrode body, the case including a pair of first walls opposing each other, a pair of second walls opposing each other, and a pair of third walls opposing each other, the electrode body having a positive electrode tab electrically connected to the positive electrode on a surface opposing one of the pair of third walls, the electrode body having a negative electrode tab electrically connected to the negative electrode on a surface opposing one 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 opposing 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 opposing the negative electrode tab, at least one of the pair of second walls including a base portion and a protruding portion protruding from the base portion in a direction away from the first end face of the electrode body, and a gas release valve that breaks when the pressure inside the case reaches or exceeds a predetermined value is provided on the protruding portion.

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

[0009] [3] The prismatic secondary battery described in [2], wherein the electrode body has a second end surface 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 surface of the electrode body, a second space is formed between the third wall and the second end surface of the electrode body, and the first space and the second space are connected to each other.

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

[0011] [5] The prismatic secondary battery according to any one of [1] to [4], wherein 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, and the gas release valve includes a first gas release valve provided in the first protrusion and a second gas release valve provided in the second protrusion. Effect of the Invention

[0012] According to the present technology, by providing a gas exhaust valve on a protruding portion protruding in a direction away from the first end face of the electrode body, it is possible to stably ensure an exhaust path through which high-temperature gas generated inside the case reaches the gas exhaust valve, and as a result, it is possible to provide a prismatic secondary battery equipped with a highly reliable gas exhaust valve. [Brief description of the drawings]

[0013] [Figure 1] 1 is a front view showing a configuration of a secondary battery according to a first embodiment. [Diagram 2] 2 is a diagram showing the secondary battery shown in FIG. 1 as viewed from the direction of arrow II. [Diagram 3] 3 is a diagram showing the secondary battery shown in FIG. 1 as viewed from the direction of arrow III. [Figure 4] 4 is a diagram showing the secondary battery shown in FIG. 1 as viewed from the direction of arrow IV. [Diagram 5] 2 is a front cross-sectional view of the secondary battery shown in FIG. [Figure 6] FIG. 2 is a front view showing a negative electrode original plate before the negative electrode plate is formed. [Figure 7] 7 is a cross-sectional view taken along the line VII-VII of the negative electrode original plate shown in FIG. 6. [Figure 8] FIG. 2 is a front view showing a negative electrode plate formed from the negative electrode original plate. [Figure 9] FIG. 2 is a front view showing a positive electrode original plate before the positive electrode plate is formed. [Figure 10] 10 is a cross-sectional view taken along the line XX in FIG. 9 . [Figure 11] FIG. 2 is a front view showing a positive electrode plate formed from a positive electrode original plate. [Figure 12] FIG. 2 is a diagram showing an electrode assembly and a current collector taken out from a secondary battery. [Figure 13] FIG. 4 is a front view of a connection structure between a negative electrode tab group and a negative electrode current collector. [Figure 14] FIG. 4 is a cross-sectional view of a connection structure between a negative electrode tab group and a negative electrode current collector. [Figure 15] FIG. [Figure 16]FIG. 2 is an enlarged view of the vicinity of the upper surface of the wound electrode body. [Figure 17] 5 is an enlarged cross-sectional view showing an example of the shape of a protrusion. FIG. [Figure 18] 11A and 11B are enlarged cross-sectional views showing modified examples of the shape of the protrusion. [Figure 19] FIG. 11 is a front cross-sectional view of a secondary battery according to a second embodiment. [Figure 20] 3 is a diagram for explaining a first space and a second space in the secondary battery according to the first embodiment. FIG. [Figure 21] 10 is a diagram for explaining a first space and a second space in a secondary battery according to a second embodiment. FIG. [Figure 22] 1 is a perspective view showing a state in which secondary batteries according to embodiment 1 are stacked to form a battery pack. [Figure 23] FIG. 1 is a diagram (part 1) showing an example of the arrangement of the protrusion and the gas exhaust valve. [Figure 24] FIG. 2 is a diagram (part 2) showing an example of the arrangement of the protrusion and the gas exhaust valve. [Diagram 25] FIG. 3 is a diagram (part 3) showing an example of the arrangement of the protrusion and the gas exhaust valve. [Figure 26] FIG. 4 is a diagram showing an example of the arrangement of the protrusion and the gas exhaust valve. [Figure 27] FIG. 5 is a diagram showing an example of the arrangement of the protrusion and the gas exhaust valve. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, embodiments of the present technology will be described. Note that the same or corresponding parts are denoted by the same reference characters, and description thereof will not be repeated.

[0015] In the embodiments described below, when referring to the number, amount, etc., the scope of the present technology is not necessarily limited to the number, amount, etc., unless otherwise specified. In addition, in the following embodiments, each component is not necessarily essential to the present technology, unless otherwise specified. In addition, the present technology is not necessarily limited to those that achieve all of the effects and advantages mentioned in the present embodiment.

[0016] In this specification, the words "comprise", "include" and "have" are open-ended, i.e., when a certain configuration is included, other configurations may or may not be included.

[0017] Furthermore, when geometric terms and terms expressing positional and directional relationships, such as "parallel," "orthogonal," "45° diagonal," "coaxial," and "along" are used in this specification, these terms allow for manufacturing errors and slight variations. When terms expressing relative positional relationships, such as "upper side" and "lower side," are used in this specification, these terms are used to indicate relative positional relationships in one state, and the relative positional relationships can be inverted or rotated to any angle depending on the installation direction of each mechanism (for example, by turning the entire mechanism upside down).

[0018] In this specification, the term "secondary battery" is not limited to lithium ion batteries, but may include other secondary batteries such as nickel-metal hydride batteries, sodium ion batteries, and solid electrolyte secondary batteries. In this specification, the term "electrode" may collectively refer to a positive electrode and a negative electrode.

[0019] In order to facilitate understanding of the invention, the dimensions of each component in the drawings may be altered from their actual dimensions.

[0020] (Embodiment 1) Fig. 1 is a front view of a secondary battery 1 according to embodiment 1. Figs. 2 to 5 are views showing the secondary battery 1 shown in Fig. 1 as viewed from the directions of arrows II, III, IV, and V, respectively. Fig. 5 is a front cross-sectional view of the secondary battery 1 shown in Fig. 1.

[0021] The secondary battery 1 can be mounted in an electric vehicle (BEV: Battery Electric Vehicle), a plug-in hybrid electric vehicle (PHEV: Plug-in Hybrid Electric Vehicle), a hybrid electric vehicle (HEV: Hybrid Electric Vehicle), etc. However, the use of the secondary battery 1 is not limited to being mounted on a vehicle.

[0022] 1 to 18 relating to embodiment 1, the direction along the winding axis of the electrode body provided in secondary battery 1 is the X direction as a first direction, the short direction of the electrode body that is perpendicular to the first direction and seen from the first direction is the Y direction as a second direction, and the long direction of the electrode body that is perpendicular to the first direction and seen from the first direction is the Z direction as a third direction.

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

[0024] 1 to 5, the secondary battery 1 includes a case 100, an electrode body 200, an electrode terminal 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 release valve 150.

[0025] The case body 110 is made of a cylindrical, more specifically, rectangular, cylindrical member. This results in a rectangular secondary battery 1. The case body 110 is made of metal. Specifically, the case body 110 is made of aluminum, an aluminum alloy, iron, an iron alloy, or the like.

[0026] As shown in Fig. 1 and Fig. 2, a first sealing plate 120 and a second sealing plate 130 are provided at both ends of the case body. The case body 110 can be formed into a square tube shape, for example, by abutting the edges of bent plate-like members (joint 115 shown in Fig. 2) and joining them together (for example, by laser welding). The corners of the "square tube" may have an R shape. The joint 115 in this embodiment extends in a first direction (X direction) on the outer circumferential surface of the case body 110.

[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 allows a relatively large (high capacity) secondary battery 1 to be configured. The dimension (height) of the case body 110 in the Z direction is preferably about 20 cm or less, more preferably about 15 cm or less, and even more preferably about 10 cm or less. This allows a relatively low height (low height) secondary battery 1 to be configured, improving the mountability in a vehicle, for example.

[0028] The case body 110 includes a pair of first side surface portions 111 (first walls) and a pair of second side surface portions 112 (second walls). The pair of first side surface portions 111 constitute a part of the side surface of the case 100. The pair of second side surface portions 112 constitute a top surface portion 112A and a bottom surface portion 112B of the case 100. The pair of first side surface portions 111 and the pair of second side surface portions 112 are provided so as to intersect with each other. The pair of first side surface portions 111 and the pair of second side surface portions 112 are connected at their respective ends. Each of the pair of first side surface portions 111 has a larger area than each of the pair of second side surface portions 112.

[0029] 3, a first opening 113 is provided at an end of a first side in a first direction (X direction) of case body 110. First opening 113 is sealed by a first sealing plate 120. First opening 113 and first sealing plate 120 have a substantially rectangular shape with a short side direction in the Y direction and a long side direction in the Z direction.

[0030] A negative electrode terminal 301 (first electrode terminal) and a liquid injection hole 121 are provided on the first sealing plate 120. The positions of the negative electrode terminal 301 and the liquid injection hole 121 can be changed as appropriate. The first sealing plate 120 can be joined to the case body 110 by, for example, laser welding.

[0031] 4, a second opening 114 is provided at an end of a second side opposite to the first side in the first direction (X direction) of case body 110. Second opening 114 is sealed by a second sealing plate 130. Second opening 114 and second sealing plate 130 have a substantially rectangular shape with a short side direction in the Y direction and a long side direction in the Z direction.

[0032] A positive electrode terminal 302 (second electrode terminal) and a liquid injection hole 131 are provided on the second sealing plate 130. The positions of the positive electrode terminal 302 and the liquid injection hole 131 can be changed as appropriate. The second sealing plate 130 can be joined to the case body 110 by, for example, laser welding.

[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, an aluminum alloy, iron, an iron alloy, or the like.

[0034] In one example, the thickness of each of the first sealing plate 120 and the second sealing plate 130 is greater than the thickness of the case body 110 (plate thickness).

[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, that is, the case 100.

[0036] The positive electrode terminal 302 is electrically connected to the positive electrode of the electrode body 200. The positive electrode terminal 302 is attached to the second sealing plate 130, i.e., the case 100.

[0037] The negative terminal 301 is made of a conductive material (more specifically, a metal), and may be made of, for example, copper or a copper alloy. The outer surface of the negative terminal 301 may be provided with a portion or layer made of aluminum or an aluminum alloy.

[0038] The positive terminal 302 is made of a conductive material (more specifically, a metal), and may be made of, for example, aluminum or an aluminum alloy.

[0039] The liquid inlet holes 121 and 131 are sealed with a sealing member (not shown) which may be, for example, a blind rivet or other metal member.

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

[0041] 5, case 100 houses electrode assembly 200. Electrode assembly 200 is housed in case 100 so that its winding axis is parallel to the X direction.

[0042] Specifically, one or more wound electrode bodies are housed inside an insulating sheet arranged in the case 100 together with an electrolytic solution (electrolyte) not shown. The insulating sheet is arranged at a position closer to the lower surface 271B (described later) of the electrode body 200 than the inner surface of the protruding portion 140 of the case 100. The "insulating sheet" here is formed separately from the separator that constitutes the electrode body 200. "Facing" in the present technology also includes, for example, facing via an "insulating sheet". However, the "insulating sheet" is not an essential component in the present technology.

[0043] The electrolyte (non-aqueous electrolyte) may be, for example, a non-aqueous solvent in which ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed in a volume ratio (25° C.) of 30:30:40, and LiPF6 is dissolved at a concentration of 1.2 mol / L. Note that a solid electrolyte may be used instead of the electrolyte.

[0044] The electrode body 200 includes a main body portion (a portion in which positive electrode plates and negative electrode plates are stacked with a separator therebetween), a negative electrode tab group 220 (first electrode tab group), and a positive electrode tab group 250 (second electrode tab group). The main body portion of the electrode body 200 corresponds to a rectangular portion excluding the negative electrode tab group 220 and the positive electrode tab group 250.

[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 an end of a first side of the electrode body 200 in a first direction (X direction) with respect to the main body. The first side in this embodiment is the first sealing plate 120 side. The positive electrode tab group 250 is located at an end of a second side in the first direction (X direction) with respect to the main body. The second side in this embodiment is the second sealing plate 130 side.

[0046] The negative electrode tab group 220 and the positive electrode tab group 250 are formed so as to protrude from the center portion of the electrode body 200 toward the first sealing plate 120 or the second sealing plate 130, respectively.

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

[0048] The negative electrode current collector 410 is disposed on the first sealing plate 120 via a resin insulating member. The negative electrode current collector 410 is electrically connected to the negative electrode tab group 220 and the negative electrode terminal 301. The negative electrode current collector 410 is made of a conductive material (more specifically, a metal), and may be made of, for example, copper or a copper alloy.

[0049] The positive electrode current collector 420 is disposed on the second sealing plate 130 via a resin insulating member. The positive electrode current collector 420 is electrically connected to the positive electrode tab group 250 and the positive electrode terminal 302. The positive electrode current collector 420 is made of a conductive material (more specifically, a metal), and may be made of, for example, aluminum or an aluminum alloy. The positive electrode tab group 250 may be electrically connected to the second sealing plate 130 directly or via the positive electrode current collector 420. In this case, the second sealing plate 130 may play the role of the positive electrode terminal 302.

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

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

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

[0053] A gas exhaust valve 150 is provided on the protruding portion 140. The gas exhaust valve 150 is formed on the bottom surface portion 112B separated from the winding axis of the wound-type electrode body 200. The gas exhaust valve 150 breaks when the pressure inside the case 100 reaches or exceeds a predetermined value. The gas exhaust valve 150 can be formed by providing the protruding portion 140 with a thin portion or a groove portion.

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

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

[0056] A negative electrode active material layer 212 is formed on both sides of the negative electrode core 211 except for one end portion. The negative electrode active material layer 212 is formed by applying a negative electrode active material layer slurry with a die coater.

[0057] The negative electrode active material layer slurry is prepared by kneading graphite as the negative electrode active material, styrene butadiene rubber (SBR) and carboxymethyl cellulose (CMC) as binders, and water as a dispersion medium so that the mass ratio of graphite:SBR:CMC is approximately 98:1:1.

[0058] The negative electrode core 211 coated with the negative electrode active material layer slurry is dried to remove water contained in the negative electrode active material layer slurry, thereby forming the negative electrode active material layer 212. Furthermore, the negative electrode active material layer 212 is compressed to form a negative electrode original plate 210S including the negative electrode core 211 and the negative electrode active material layer 212. The negative electrode original plate 210S is cut into a predetermined shape to form the negative electrode plate 210. The negative electrode original plate 210S can be cut by laser processing using energy beam irradiation, die processing, cutter processing, or the like.

[0059] As shown in FIG. 8, a plurality of negative electrode tabs 230 made of a negative electrode core 211 are provided at one end in the width direction of a negative electrode plate 210 formed from a negative electrode original plate 210S. When the negative electrode plate 210 is wound, the plurality of negative electrode tabs 230 are stacked to form a negative electrode tab group 220. As a result, the negative electrode tab group 220 is connected to the negative electrode plate 210 (first electrode). The position and length in the protruding direction of each of the plurality of negative electrode tabs 230 are appropriately adjusted in consideration of the state in which the negative electrode tab group 220 is connected to the negative electrode current collector 410. The shape of the negative electrode tab 230 is not limited to the one exemplified in FIG. 8.

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

[0061] The positive electrode plate 240, which is the second electrode, has a polarity different from that of the negative electrode plate 210, which is the first electrode. The positive electrode plate 240 is manufactured by processing a positive electrode original plate 240S. As shown in Fig. 9 and Fig. 10, the positive electrode original plate 240S includes a positive electrode core body 241, a positive electrode active material layer 242, and a positive electrode protective layer 243. The positive electrode core body 241 is an aluminum foil or an aluminum alloy foil.

[0062] A positive electrode active material layer 242 is formed on both sides of the positive electrode core 241 except for one end portion. The positive electrode active material layer 242 is formed on the positive electrode core 241 by applying a positive electrode active material layer slurry with a die coater.

[0063] The positive electrode active material layer slurry is prepared by kneading lithium nickel cobalt manganese composite oxide as the positive electrode active material, polyvinylidene fluoride (PVdF) as a binder, a carbon material as a conductive material, and N-methyl-2-pyrrolidone (NMP) as a dispersion medium, so that the mass ratio of lithium nickel cobalt manganese composite oxide:PVdF:carbon material is approximately 97.5:1:1.5.

[0064] The positive electrode protective layer 243 is in contact with the positive electrode core 241 and is formed at one end in the width direction of the positive electrode active material layer 242. The positive electrode protective layer 243 is formed on the positive electrode core 241 by applying a positive electrode protective layer slurry with a die coater. The positive electrode protective layer 243 has a larger electric resistance than the positive electrode active material layer 242.

[0065] The positive electrode protective layer slurry is prepared by kneading alumina powder, a carbon material as a conductive material, PVdF as a binder, and NMP as a dispersion medium so that the mass ratio of alumina powder:carbon material:PVdF is approximately 83:3:14.

[0066] The positive electrode core 241 coated with the positive electrode active material layer slurry and the positive electrode protective layer slurry is dried, and the NMP contained in the positive electrode active material layer slurry and the positive electrode protective layer slurry is removed to form the positive electrode active material layer 242 and the positive electrode protective layer 243. Furthermore, the positive electrode active material layer 242 is compressed to form a positive electrode original plate 240S including the positive electrode core 241, the positive electrode active material layer 242, and the positive electrode protective layer 243. The positive electrode original plate 240S is cut into a predetermined shape to form the positive electrode plate 240. The positive electrode original plate 240S can be cut by laser processing using energy beam irradiation, die processing, cutter processing, or the like.

[0067] As shown in FIG. 11, a plurality of positive electrode tabs 260 made of a positive electrode core 241 are provided at one end in the width direction of the positive electrode plate 240 formed from the positive electrode original plate 240S. When the positive electrode plate 240 is wound, the plurality of positive electrode tabs 260 are stacked to form a positive electrode tab group 250. As a result, the positive electrode tab group 250 is connected to the positive electrode plate 240 (second electrode). The position and length in the protruding direction of each of the plurality of positive electrode tabs 260 are appropriately adjusted in consideration of the state in which the positive electrode tab group 250 is connected to the positive electrode current collector 420. The shape of the positive electrode tab 260 is not limited to the one exemplified in FIG. 11.

[0068] A positive electrode protection layer 243 is provided at the base of each of the positive electrode tabs 260. The positive electrode protection layer 243 does not necessarily have to be provided at the base of the positive electrode tab 260.

[0069] In a typical example, the thickness of the negative electrode tab 230 (one piece) is smaller than the thickness of the positive electrode tab 260 (one piece). In this case, the thickness of the negative electrode tab group 220 is smaller than the thickness of the positive electrode tab group 250.

[0070] Fig. 12 is a diagram showing the electrode body 200 and the current collector 400 taken out from the secondary battery 1. As shown in Fig. 12, the electrode body 200 is formed by stacking two electrode bodies 201, 202, each of which is a wound type electrode body. In the example shown in Fig. 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, may be composed of three or more wound type electrode bodies, or may be composed of a laminated type electrode body.

[0071] The negative electrode tab group 220 is joined to the negative electrode current collector 410 at joint points 434 , and the positive electrode tab group 250 is joined to the positive electrode current collector 420 at joint points 454 .

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

[0073] 13 and 14, the negative electrode current collector 410 electrically connects the negative electrode terminal 301 and the negative electrode tab group 220. The negative electrode current collector 410 in this embodiment is connected to the negative electrode terminal 301 between the electrode body 200 and the 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 portion 433. The first conductive member 430 and the second conductive member 440 are joined by, for example, laser welding.

[0075] The first conductive member 430 is joined to the negative electrode tab group 220 at a joint 434. The joint 434 can be formed by, for example, ultrasonic welding, resistance welding, laser welding, crimping, etc. In the present embodiment, the first conductive member 430 and the negative electrode tab group 220 are joined by, for example, ultrasonic bonding.

[0076] Second conductive member 440 is connected to negative terminal 301 at joint 441. Joint 441 may be formed by, for example, ultrasonic welding, resistance welding, laser welding, crimping, or the like. In this embodiment, negative terminal 301 and second conductive member 440 are joined by, for example, providing a through hole in second conductive member 440, inserting negative terminal 301 into the through hole, crimping negative terminal 301 onto second conductive member 440, and then welding the crimped portion to second conductive member 440.

[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 disposed along the first sealing plate 120.

[0078] A step portion 435 is provided between the first flat portion 431 and the second flat portion 432. The step portion 435 makes the positions of the first flat portion 431 and the second flat portion 432 in the first direction (X direction) different after the secondary battery 1 is assembled. This allows the first flat portion 431 and the second flat portion 432 to be arranged side by side in one direction. The step portion 435 extends along the third direction (Z direction).

[0079] A first insulating member 510 (resin member) is disposed between the negative electrode terminal 301 and the first sealing plate 120. A second insulating member 520 (resin member) is disposed between the first sealing plate 120 and the first conductive member 430 and the second conductive member 440. The first insulating member 510 and the second insulating member 520 may be an integrated part.

[0080] Negative electrode terminal 301 is attached to first sealing plate 120 via first insulating member 510. Negative electrode terminal 301 is provided so as to be exposed to the outside of first sealing plate 120 and to reach second conductive member 440 of negative electrode current collector 410 provided on the inner surface side of first sealing plate 120.

[0081] The procedure for assembling each part is as follows: first, the negative electrode terminal 301 and the second conductive member 440 are attached to the first sealing plate 120 together with the first insulating member 510 and the second insulating member 520. Next, the first conductive member 430 electrically connected to the electrode body 200 is attached to the second conductive member 440. At this time, the first conductive member 430 is placed on the first insulating member 510 so that a portion of the first conductive member 430 overlaps with the second conductive member 440. Next, the first conductive member 430 and the second conductive member 440 are connected by welding at a joint 434.

[0082] However, negative electrode terminal 301 may be electrically connected to first sealing plate 120. Also, first sealing plate 120 may play the role of negative electrode terminal 301.

[0083] 13 and 14, the negative electrode current collector 410 is illustrated as being made up of two components (the first conductive member 430 and the second conductive member 440), but the negative electrode current collector 410 may be made up of a single component.

[0084] Although the connection structure on the negative electrode side is shown in FIG. 13 and FIG. 14, the basic connection structure on the positive electrode side is similar to that on the negative electrode side.

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

[0086] Fig. 16 is an enlarged view of the vicinity of upper surface 271A of electrode body 200. As shown in Fig. 16, when electrode body 200 is formed by stacking wound electrode bodies 201, 202, curved surfaces 201A, 202A of electrode bodies 201, 202 are joined together to form upper surface 271A of electrode body 200.

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

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

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

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

[0091] In both the examples of Figures 17 and 18, the space (first space) formed between the protrusion 140 and the lower surface 271B (first end surface) of the electrode body 200 is connected to the space (second space) formed between the first sealing plate 120 and the short side surface 272A (second end surface) of the electrode body 200.

[0092] In this way, it is possible to stably secure an exhaust path reaching the gas exhaust valve 150 within the case 100. Specifically, it is possible to guide the gas discharged from the short side surface 272A of the wound-type electrode body 200 to the outside of the electrode body 200 to the space formed inside the protruding portion 140, and to exhaust it to the outside of the case 100 via the gas exhaust valve 150 formed in the protruding portion 140. However, in the present technology, the above two spaces (the first space and the second space) do not necessarily have to be directly connected to each other.

[0093] (Embodiment 2) 19 is a front cross-sectional view of a secondary battery 10 according to Embodiment 2. As shown in FIG.

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

[0095] The electrode body 2000 has a pair of side surfaces 2710 (first end surfaces) and an upper surface 2720 (second end surface). A negative electrode tab group 2200 and a positive electrode tab group 2500 are provided on the upper surface 2720. 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 FIG. 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. The protrusion 1400 includes a left protrusion 1400 (first protrusion) provided at a position facing the side surface 2710A of the electrode body 2000, and a right protrusion 1400 (second protrusion) provided at a position facing the side surface 2710B of the electrode body 2000. The gas exhaust valve 1500 includes a left gas exhaust valve 1500 (first gas exhaust valve) provided on the left protrusion 1400, and a right gas exhaust valve 1500 (second gas exhaust valve) provided on the right protrusion 1400. That is, in this embodiment, the pair of gas exhaust valves 1500 are both formed on the side surface portion 1100 separated from the winding axis of the wound electrode body 2000.

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

[0099] As other points are similar to those in the first embodiment, detailed description will not be repeated.

[0100] (1st space and 2nd space) 20 and 21 are diagrams for explaining the space inside the case of the secondary batteries 1 and 10 according to the first and second embodiments, respectively. The dashed lines in Fig. 20 and Fig. 21 are imaginary straight lines extending in the extension direction of the inner surface of the base portion.

[0101] In the example of Figure 20 (embodiment 1), a first space 11 is formed between the protrusion 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 of FIG. 21 (embodiment 2), a first space 11 is formed between the protrusion 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] 20, the width of the second space 12, i.e., the distance between the short side surface 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. Also in the example of Fig. 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 of FIGS. 20 and 21, the length L of the protrusions 140 and 1400 140 ,L 1400 are, for example, 1 / 10 or more of the total length of the cases 100 and 1000 in the same direction.

[0105] In the example of FIG. 20 and FIG. 21, the volume of the first space 11 is 120 mm 3 More than 200mm (preferably 200mm 3 More preferably, 300 mm 3 More preferably, 400 mm 3 The ratio (volume percentage) of the volume of the first space 11 to the internal volume of the case 100 is preferably about 0.05 percent or more. The volume of the second space 12 is preferably 1100 mm 3It is preferable that the ratio (volume percentage) of the volume of the second space 12 to the internal volume of the case 100, 1000 is about 1.5 percent or more.

[0106] The internal volume of the cases 100, 100 and the volumes of the first space 11 and the second space 12 mentioned here are values ​​calculated including the volume of the space occupied by the electrode assemblies 200, 2000 or other components.

[0107] According to the first space 11 and the second space 12 illustrated in Figures 20 and 21, it is possible to reliably connect the first space 11 formed inside the protrusions 140, 1400 and the second space 12 adjacent to the short side 272A or the upper surface 2720 of the electrode body 200, and to reliably secure an exhaust path within the case that leads gas ejected from the electrode body 200 to the gas exhaust valve 150.

[0108] (Battery assembly configuration) FIG. 22 is a perspective view showing a state in which the secondary batteries 1 according to the first embodiment are stacked to form a battery pack.

[0109] As shown in FIG. 22, when constructing an assembled battery including secondary batteries 1, multiple secondary batteries 1 are stacked in their thickness direction. End plates 2 are provided on both ends of the stacked secondary batteries 1. A stack of secondary batteries 1 and end plates 2 is restrained in the stacking direction (Y direction) by restraining members 3 to construct an assembled battery. Both ends of the restraining members 3 are fixed to the end plates 2 by fastening members 4. The multiple secondary batteries 1 are electrically connected by bus bars 5. In FIG. 22, secondary batteries 1 are omitted from the center in the Y direction, but the number of stacked secondary batteries 1 can be changed as appropriate.

[0110] A duct for flowing gas discharged from the gas exhaust valve 150 in the Y direction can be provided at a position avoiding the restraining member 3.

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

[0112] (Arrangement of protrusion 140 and gas exhaust valve 150) 23 to 27 are diagrams showing examples of the arrangement of the protrusions 140 and the gas release valve 150 in the secondary battery 1 according to the first embodiment.

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

[0114] In any of the examples in Figures 23 to 27, the first space 11 formed inside the protrusion 140 and the second space 12 formed on both sides of the electrode body 200 can be connected to each other, thereby reliably securing an exhaust path through which gas and the like discharged from the short side 272A of the electrode body 200 reaches the gas exhaust valve 150.

[0115] 23 to 27, for example, a plurality of gas exhaust valves 150 may be arranged on one protruding portion 140. In addition, the shapes and sizes of the protruding portion 140 and the gas exhaust valve 150 may be changed as appropriate.

[0116] (Action and effect) According to the secondary battery 1, 10 described above, by providing the gas exhaust valve 150, 1500 on the protruding portion 140, 1400 protruding in a direction away from the electrode body 200, 2000, it is possible to stably secure an exhaust path through which high-temperature gas generated in the case 100, 1000 reaches the gas exhaust valve. Therefore, when the internal pressure of the case 100, 1000 rises and it becomes necessary to exhaust gas, the gas exhaust valve 150, 1500 can be stably operated and unintended rupture can be suppressed. Thus, according to the secondary battery 1, 10 described above, it is possible to improve the reliability of the gas exhaust valve 150, 1500.

[0117] Although the embodiment of the present technology has been described above, the embodiment disclosed herein should be considered as illustrative and not restrictive in all respects. The scope of the present technology is defined by the claims, and it is intended to include all modifications within the scope and meaning equivalent to the claims. [Explanation of symbols]

[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 portion, 112 second side portion, 112A top surface portion, 112B bottom surface portion, 112B0 base portion, 113 first opening, 114 second opening, 115 joint portion, 120 first sealing plate, 121 liquid injection hole, 130 second sealing plate, 131 liquid injection hole, 140 protrusion, 150 gas release 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 original 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 Upper surface, 271B Lower 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 flat portion, 432 Second flat portion, 433, 434, 441, 454 Joint portion, 435 Step portion, 440 Second conductive member, 510 First insulating member, 520 Second insulating member, 1000 Case, 1100 side portion, 1200 sealing plate, 1300 bottom portion, 1400 protrusion, 1500 gas exhaust valve, 2000 electrode body, 2200 negative electrode tab group, 2500 positive electrode tab group, 2710, 2710A, 2710B sides, 2720 top surface, 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 assembly including a positive electrode and a negative electrode; A case for accommodating the electrode body, the case includes a pair of first walls opposed to each other, a pair of second walls opposed to each other, and a pair of third walls opposed to 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 one 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 one 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 protruding portion protruding from the base portion in a direction away from the first end surface of the electrode body, A gas release valve that breaks when pressure inside the case reaches or exceeds a predetermined value is provided on the protruding portion.

2. The prismatic secondary battery according to claim 1 , wherein at least one of the pair of third walls is connected to a portion of the second wall where the protrusion is provided.

3. the electrode body has a second end surface on which at least one of the positive electrode tab and the negative electrode tab is provided, a first space is formed between the protrusion and a first end surface of the electrode body; a second space is formed between the third wall and the second end surface of the electrode body, The prismatic secondary battery according to claim 2 , wherein the first space and the second space communicate with each other.

4. an insulating sheet disposed between the protrusion and the first end surface of the electrode body; The prismatic secondary battery according to claim 1 , wherein the insulating sheet is disposed at a position closer to the first end face of the electrode body than an inner surface of the protruding portion.

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, 4. The prismatic secondary battery according to claim 1, wherein the gas exhaust valve includes a first gas exhaust valve provided in the first protruding portion and a second gas exhaust valve provided in the second protruding portion.

Images