Power storage device

Abstract

To provide a power storage device capable of suppressing heat generation within a case after gas is discharged through a pressure relief valve.SOLUTION: A power storage device 1 includes a plurality of power storage stacks 110, a case 500 including a one-side space S2, a pressure relief valve 600, and a breathing membrane 700. The case 500 includes a bottom wall 512, a side wall 514a, and a top wall. The pressure relief valve 600 is provided at a location above the one-side space S2 in the top wall. The side wall 514a overlaps, across the entire second direction, with a virtual projection plane R that is an extension in the second direction of the projected area of the pressure relief valve 600. The bottom wall 512 and the side wall 514a include an overlapping portion 515 that overlaps with the virtual projection plane R. The breathing membrane 700 is provided in the overlapping portion 515.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to an electricity storage device. [Background technology]

[0002] For example, Japanese Patent Application Laid-Open Publication No. 2023-47012 discloses a battery pack including a plurality of battery cells, a case for accommodating the plurality of battery cells, a pressure release valve provided in the case, and a breather membrane provided in the case. The case has a lower case and an upper cover. The pressure release valve is provided in the upper cover, and the breather membrane is provided in a side wall portion of the lower case. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-47012 Summary of the Invention [Problem to be solved by the invention]

[0004] In the battery pack described in JP 2023-47012 A, when gas is generated from one of the battery cells and the pressure inside the case reaches a reference value, the gas is released through the pressure release valve, and then air flows into the case through the breathing membrane to adjust the internal pressure of the case.

[0005] At this time, if a battery cell other than the battery cell from which gas was previously generated is generating heat, there is a concern that the air flowing into the case through the breathing membrane will reach that battery cell, thereby accelerating the generation of heat.

[0006] An object of the present disclosure is to provide an electricity storage device that can suppress the promotion of heat generation inside the case after gas is discharged through a pressure release valve. [Means for solving the problem]

[0007] According to one aspect of the present disclosure, there is provided a power storage device including: a plurality of power storage stacks arranged in a line along a first direction; a case that houses the plurality of power storage stacks and includes a one-side space formed on one side of the plurality of power storage stacks in the first direction; a pressure release valve that is provided in the case and releases pressure inside the case; and a breathing membrane that is provided in the case and adjusts the pressure inside the case by allowing gas to pass between the inside and outside of the case, wherein the case supports the plurality of power storage stacks. the pressure release valve is provided in a portion of the upper wall above the one-side space, and the side wall overlaps with a virtual projection plane that is an extension of a projection plane of the pressure release valve in a second direction perpendicular to both the first direction and the up-down direction, the bottom wall and the side wall include overlapping portions that overlap with the virtual projection plane, and the breathing membrane is provided in the overlapping portion. [Effects of the Invention]

[0008] According to the present disclosure, it is possible to provide an electricity storage device that can suppress the promotion of heat generation inside the case after gas is discharged through the pressure release valve. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a perspective view schematically illustrating a power storage device according to an embodiment of the present disclosure. [Figure 2] 2 is a perspective view schematically illustrating a state in which an upper cover is removed from the electricity storage device illustrated in FIG. 1. FIG. [Figure 3] FIG. 2 is a plan view schematically showing a state in which an upper cover is removed from the power storage device. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. [Figure 5] FIG. 10 is a diagram schematically illustrating a modified example of the power storage device. [Figure 6]FIG. 10 is a diagram schematically illustrating a modified example of the power storage device. DETAILED DESCRIPTION OF THE INVENTION

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The present disclosure will be described with reference to the accompanying drawings, in which the same or corresponding elements are designated by the same reference numerals.

[0011] Fig. 1 is a perspective view that schematically shows an electricity storage device according to an embodiment of the present disclosure. Fig. 2 is a perspective view that schematically shows a state in which an upper cover and a covering plate are removed from the electricity storage device shown in Fig. 1. Fig. 3 is a plan view that schematically shows a state in which the upper cover and the covering plate are removed from the electricity storage device. Fig. 4 is a cross-sectional view taken along line IV-IV in Fig. 1. This electricity storage device 1 is mounted, for example, on the bottom of a vehicle.

[0012] As shown in Figures 1 to 4, the energy storage device 1 includes a plurality of first energy storage stacks 110, a plurality of second energy storage stacks 120, a first bus bar 210, a second bus bar 220, a first junction box 310, a second junction box 320, a covering plate 400, a case 500, a pressure release valve 600, and a breathing membrane 700.

[0013] The multiple first power storage stacks 110 are arranged side by side in a first direction. In this embodiment, the multiple first power storage stacks 110 include six first power storage stacks 110. However, the number of first power storage stacks 110 is not limited to six. Each first power storage stack 110 is formed in a rectangular parallelepiped shape that is long in a second direction that is perpendicular to both the first direction and the up-down direction. The first power storage stack 110 is an example of a "power storage stack" in the present disclosure.

[0014] Each first power storage stack 110 includes a plurality of power storage cells 111 (see FIG. 4). The plurality of power storage cells 111 are arranged, for example, to be aligned in a first direction. The plurality of power storage cells 111 may also be arranged to be aligned in a second direction. Each power storage cell 111 is formed in a flat rectangular parallelepiped shape. An example of each power storage cell 111 is a lithium ion battery. Each power storage cell 111 may be formed as an all-solid-state battery using a solid electrolyte. As shown in FIG. 4, each power storage cell 111 includes a safety valve 111a provided at a position facing the upper cover 520, i.e., on the upper surface of the housing of the power storage cell 111.

[0015] The multiple second power storage stacks 120 are arranged to face the multiple first power storage stacks 110 in the second direction and to be aligned in the first direction. In this embodiment, the multiple second power storage stacks 120 include six second power storage stacks 120. However, the number of second power storage stacks 120 is not limited to six. The configuration of each second power storage stack 120 is the same as the configuration of the first power storage stack 110. The second power storage stack 120 is an example of "another power storage stack" in the present disclosure.

[0016] The first bus bar 210 connects a pair of first power storage stacks 110 adjacent to each other in the first direction. The first bus bar 210 is routed in a routing space S1 (see FIG. 3 ) between the plurality of first power storage stacks 110 and the plurality of second power storage stacks 120. Note that the first bus bar 210 and the second bus bar 220 are not shown in FIG. 3 .

[0017] The second bus bar 220 connects a pair of second power storage stacks 120 adjacent to each other in the first direction. The second bus bar 220 is routed in the routing space S1.

[0018] The first junction box 310 is disposed at a position facing, in the first direction, a first power storage stack 110 that is disposed outermost in the first direction among the multiple first power storage stacks 110 (for example, on the front side in the front-to-rear direction of the vehicle). The first junction box 310 houses a relay, a fuse, and the like. The first junction box 310 has a first connector 312. The first connector 312 protrudes outward in the first direction.

[0019] The second junction box 320 is disposed at a position facing the second power storage stack 120 in the first direction and facing the first junction box 310 at an interval in the second direction. The second junction box 320 houses a relay, a fuse, and the like. As shown in FIG. 2 , in this embodiment, the outer shape of the second junction box 320 is larger than the outer shape of the first junction box 310. The second junction box 320 has a second connector 322. The second connector 322 protrudes outward in the first direction.

[0020] The covering plate 400 (see FIG. 4) covers the first bus bar 210 and the second bus bar 220 from above. The covering plate 400 is disposed between the plurality of first power storage stacks 110 and the plurality of second power storage stacks 120. The covering plate 400 extends along a first direction. The covering plate 400 is formed in a flat plate shape. The covering plate 400 is made of an insulating material. The covering plate 400 is made of, for example, mica, which is a natural inorganic mineral solidified by heat pressing. The covering plate 400 has the function of blocking gas ejected upward from any of the power storage stacks from coming into contact with the bus bars 210, 220. Note that the covering plate 400 is not shown in FIGS. 2 and 3.

[0021] The case 500 accommodates a plurality of first power storage stacks 110, a plurality of second power storage stacks 120, a first bus bar 210, a second bus bar 220, a first junction box 310, a second junction box 320, and a cover plate 400. The case 500 includes a one-side space S2 formed on one side of the plurality of first power storage stacks 110 and the plurality of second power storage stacks 120 in the first direction. The junction boxes 310, 320 are arranged in this one-side space S2. The case 500 has a lower case 510 and an upper cover 520.

[0022] The lower case 510 is open upward and has a bottom wall 512, a peripheral wall 514, and a partition 516.

[0023] The bottom wall 512 supports each of the power storage stacks 110, 120.

[0024] The peripheral wall 514 stands upright from the peripheral edge of the bottom wall 512. The peripheral wall 514 surrounds the periphery of the plurality of first power storage stacks 110 and the plurality of second power storage stacks 120. The peripheral wall 514 is formed in a substantially rectangular cylindrical shape.

[0025] As shown in Figures 2 and 3, the length between each junction box 310, 320 in the second direction is smaller than the length between the first junction box 310 and the peripheral wall 514 in the second direction, and is also smaller than the length between the second junction box 320 and the peripheral wall 514 in the second direction.

[0026] The peripheral wall 514 includes a side wall 514a formed on the opposite side (left side in FIG. 3 ) from the side on which the multiple first power storage stacks 110 and the multiple second power storage stacks 120 are arranged, with the first junction box 310 and the second junction box 320 as references. In other words, the side wall 514a faces the power storage stacks 110, 120 in the first direction, with the one side space S2 between them. The side wall 514a extends along the second direction. The side wall 514a may be inclined gradually outward in the first direction as it extends upward, or may be perpendicular to the bottom wall 512.

[0027] The partition 516 separates the plurality of first power storage stacks 110 from the plurality of second power storage stacks 120. The partition 516 has a shape that extends along the first direction. The height of the partition 516 is lower than the height of the peripheral wall 514. As shown in FIGS. 3 and 4 , a wiring space S1 is formed between the partition 516 and the cover plate 400.

[0028] Upper cover 520, together with lower case 510, accommodates a plurality of first power storage stacks 110, a plurality of second power storage stacks 120, first bus bar 210, second bus bar 220, first junction box 310, second junction box 320, and cover plate 400. The peripheral edge of upper cover 520 is fixed to the upper end of peripheral wall 514 with bolts or the like.

[0029] Upper cover 520 has an upper wall 522. Upper wall 522 faces bottom wall 512. Upper wall 522 covers the plurality of first power storage stacks 110, the plurality of second power storage stacks 120, first bus bar 210, second bus bar 220, first junction box 310, second junction box 320, and cover plate 400.

[0030] The pressure release valve 600 is provided in the case 500. The pressure release valve 600 releases pressure inside the case 500. The pressure release valve 600 opens when the pressure inside the case 500 reaches or exceeds a reference value. The pressure release valve 600 is configured as a check valve. As shown in FIGS. 3 and 4, the pressure release valve 600 is provided in a portion of the upper wall 522 above the one-side space S2. In this embodiment, the pressure release valve 600 is provided in a portion of the upper wall 522 above an inter-box space S3 (see FIG. 4) formed between the first junction box 310 and the second junction box 320. The inter-box space S3 is part of the one-side space S2.

[0031] 4, a shielding portion 525 is provided on the inner surface of the upper cover 520. The shielding portion 525 is provided on a path connecting the safety valve 111a and the pressure release valve 600. In this embodiment, the shielding portion 525 is provided on a portion of the inner surface of the upper cover 520 in front of each of the power storage stacks 110, 120. The shielding portion 525 is provided above the inter-box space S3. The shielding portion 525 has a shape that extends downward from the upper cover 520.

[0032] The breathing membrane 700 is provided on the case 500. The breathing membrane 700 adjusts the pressure inside the case 500 by allowing gas to pass between the inside and outside of the case 500.

[0033] 3 and 4, the bottom wall 512 and the side wall 514a include an overlapping portion 515 that overlaps with a virtual projection plane R formed by extending the projection plane of the pressure release valve 600 (the area indicated by the two-dot chain line in FIG. 3) in the second direction. The breathing membrane 700 is provided in the overlapping portion 515. As shown in FIG. 3, the side wall 514a overlaps with the virtual projection plane R over the entire area in the second direction. Note that in FIG. 3, the virtual projection plane R is indicated by dots.

[0034] The breathing membrane 700 is preferably disposed on the opposite side of the pressure release valve 600 from the side on which the power storage stacks 110, 120 are disposed. In this embodiment, the breathing membrane 700 is provided at the overlapping portion 515 of the side wall 514a. Specifically, a through-hole is provided in the side wall 514a, and the breathing membrane 700 is attached to the outer surface of the side wall 514a so as to cover the through-hole.

[0035] It is more preferable that the breathing film 700 be provided on the outer surface of the region of the overlapping portion 515 of the side wall 514a that faces the first junction box 310 and the second junction box 320.

[0036] As described above, in the energy storage device 1 of this embodiment, the side wall 514a overlaps with the imaginary projection plane R over the entire area in the second direction, and the breathing membrane 700 is provided at the overlapping portion 515 that overlaps with the imaginary projection plane R, thereby reducing the volume of the one-side space S2. Therefore, after the gas is discharged to the outside of the case 500 through the pressure release valve 600, the amount of air that flows into the case 500 through the breathing membrane 700 and remains in the one-side space S2, i.e., the amount of oxygen in the one-side space S2, is reduced. Therefore, even if a heat-generating spot occurs in either of the energy storage stacks 110, 120, the promotion of heat generation in the case 500 after the gas is discharged through the pressure release valve 600 is suppressed.

[0037] Furthermore, since the volume of the one-side space S2 is relatively small, the strength of the case 500 required when combustion occurs inside the case 500 is effectively ensured.

[0038] Furthermore, if air flows into the case 500 through the breathing film 700 after the gas is discharged from the pressure release valve 600, the air comes into contact with the junction boxes 310, 320 and tends to stagnate in the one-side space S2. This prevents the air that has flowed into the case 500 through the breathing film 700 from reaching the power storage stacks 110, 120 and the resulting generation of blasts, etc.

[0039] Modifications of the above embodiment will now be described.

[0040] <First Modification> As shown in FIG. 5, when the outer shape of the second junction box 320 is larger than the outer shape of the first junction box 310, the breathing membrane 700 may be provided in a portion of the side wall 514a that faces the second junction box 320.

[0041] <Second Modification> As shown in FIG. 6, the breathing membrane 700 may be provided at the overlapping portion 515 of the bottom wall 512 .

[0042] <Third Modification> Although not shown in the drawings, the plurality of second power storage stacks 120 may be omitted.

[0043] It will be appreciated by those skilled in the art that the exemplary embodiments described above are examples of the following aspects.

[0044] [Aspect 1] a plurality of power storage stacks arranged in a line along a first direction; a case that accommodates the plurality of power storage stacks and includes a one-side space that is formed on one side of the plurality of power storage stacks in the first direction; a pressure relief valve provided in the case for releasing pressure inside the case; a breathing membrane provided in the case, which adjusts the pressure inside the case by allowing gas to pass between the inside of the case and the outside of the case; The case is a bottom wall supporting the plurality of power storage stacks; a side wall facing the plurality of power storage stacks in the first direction across the one-side space; a top wall covering the plurality of power storage stacks; the pressure release valve is provided in a portion of the upper wall above the one-side space, the side wall overlaps with a virtual projection plane obtained by extending a projection plane of the pressure release valve in the second direction, over an entire area in a second direction perpendicular to both the first direction and the up-and-down direction, the bottom wall and the side wall include overlapping portions that overlap with the virtual projection plane, The breathing membrane is provided in the overlapping portion.

[0045] In this energy storage device, the side wall overlaps the virtual projection plane over the entire area in the second direction, and the breathing membrane is provided at the overlapping portion where the breathing membrane overlaps with the virtual projection plane, thereby reducing the volume of the one-side space. Therefore, after gas is discharged to the outside of the case through the pressure release valve, the amount of air that flows into the case through the breathing membrane and remains in the one-side space, i.e., the amount of oxygen in the one-side space, is reduced. Therefore, even if a heat-generating spot occurs in any of the energy storage stacks, the promotion of heat generation in the case after gas is discharged through the pressure release valve is suppressed.

[0046] [Aspect 2] the breathing membrane is provided in the overlapping portion of the side wall, 2. The power storage device of claim 1, wherein at least a portion of the breathing membrane overlaps with the projection surface of the pressure relief valve.

[0047] In this embodiment, the amount of oxygen in one side space is smaller.

[0048] [Aspect 3] a plurality of other power storage stacks arranged to face the plurality of power storage stacks in the second direction and to be aligned along the first direction; a first junction box arranged in the one-side space at a position facing the power storage stack in the first direction; a second junction box disposed in the one-side space at a position facing the other power storage stack in the first direction and facing the first junction box at an interval in the second direction, the pressure release valve is provided in a portion of the upper wall above an inter-box space between the first junction box and the second junction box, 3. The power storage device according to aspect 2, wherein the breathing film is provided on a portion of the side wall that faces the inter-box space.

[0049] In this embodiment, when air flows into the case through the breathing membrane after gas is discharged from the pressure release valve, the air comes into contact with each junction box and is more likely to stagnate in the space on one side.

[0050] It should be noted that the embodiments disclosed herein are illustrative in all respects and should not be considered limiting. The scope of the present disclosure is defined by the claims rather than the description of the above embodiments, and further includes all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0051] 1 energy storage device, 110 first energy storage stack (energy storage stack), 111 energy storage cell, 111a safety valve, 120 second energy storage stack (another energy storage stack), 210 first bus bar, 220 second bus bar, 310 first junction box, 312 first connector, 320 second junction box, 322 second connector, 400 covering plate, 500 case, 510 lower case, 512 bottom wall, 514 surrounding wall, 514a side wall, 515 overlapping portion, 520 upper cover, 522 top wall, 525 shielding portion, 600 pressure release valve, 700 breathing membrane, R virtual projection surface, S1 wiring space, S2 one side space, S3 inter-box space.

Claims

1. a plurality of power storage stacks arranged to be aligned along a first direction; a case that accommodates the plurality of power storage stacks and includes a one-side space that is formed on one side of the plurality of power storage stacks in the first direction; a pressure relief valve provided in the case for releasing pressure inside the case; a breathing membrane provided in the case, which adjusts the pressure inside the case by allowing gas to pass between the inside of the case and the outside of the case; The case is a bottom wall supporting the plurality of power storage stacks; a side wall facing the plurality of power storage stacks in the first direction across the one-side space; a top wall covering the plurality of power storage stacks; the pressure release valve is provided in a portion of the upper wall above the one-side space, the side wall overlaps with a virtual projection plane obtained by extending a projection plane of the pressure release valve in the second direction, over an entire area in a second direction perpendicular to both the first direction and the up-and-down direction, the bottom wall and the side wall include overlapping portions that overlap with the virtual projection plane, The breathing membrane is provided in the overlapping portion.

2. the breathing membrane is provided in the overlapping portion of the side wall, The power storage device according to claim 1 , wherein at least a portion of the breathing membrane overlaps with the projection surface of the pressure release valve.

3. a plurality of other power storage stacks arranged to face the plurality of power storage stacks in the second direction and to be aligned along the first direction; a first junction box disposed in the one-side space at a position facing the power storage stack in the first direction; a second junction box disposed in the one-side space at a position facing the other power storage stack in the first direction and facing the first junction box at an interval in the second direction, the pressure release valve is provided in a portion of the upper wall above an inter-box space between the first junction box and the second junction box, The power storage device according to claim 2 , wherein the breathing membrane is provided on a portion of the side wall that faces the inter-box space.

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