Power storage device

Abstract

A power storage device (1) comprises: a plurality of power storage modules (101); a case in which the plurality of power storage modules are accommodated; a pressure release valve (600) which is provided in the case; and a breathing film (700) which is provided in the case. Each of the plurality of power storage modules (101) has an exhaust port (h) for discharging gas. The distance (D1) between the breathing film (700) and the pressure release valve (600) is shorter than the distance (D2) between the exhaust port (h) and the pressure release valve (600).

Description

Power storage device

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

[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 on a side wall of the lower case.

[0003] Japanese Patent Application Laid-Open No. 2023-47012

[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 heat generation will be accelerated inside the case when air comes into contact with the blast generated from that battery cell.

[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.

[0007] According to one aspect of the present disclosure, there is provided a power storage device comprising: a plurality of power storage modules arranged in a line along a first direction; a case that houses the plurality of power storage modules; a pressure relief valve provided in the case that relieves pressure within the case; and a breathing membrane provided in the case that adjusts the pressure within the case by allowing gas to pass between the inside and outside of the case, wherein each of the plurality of power storage modules has an exhaust port for discharging gas, and the distance between the breathing membrane and the pressure relief valve is smaller than the distance between the exhaust port and the pressure relief valve.

[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.

[0009] 1 is a perspective view schematically showing an electricity storage device according to an embodiment of the present disclosure; FIG. 2 is a perspective view schematically showing a state in which an upper cover and a covering plate have been removed from the electricity storage device shown in FIG. 1; FIG. 3 is a plan view schematically showing a state in which an upper cover and a covering plate have been removed from the electricity storage device; FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 3; FIG. 5 is a cross-sectional view taken along line V-V in FIG. 3; FIG. 6 is a cross-sectional view schematically showing a modified example of the electricity storage device; FIG. 7 is a plan view schematically showing a modified example of the electricity storage device;

[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 electric 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 electric 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 electric storage device. Fig. 4 is a cross-sectional view taken along line IV-IV in Fig. 3. Fig. 5 is a cross-sectional view taken along line V-V in Fig. 3. This electric storage device 1 is mounted, for example, on the bottom of a vehicle.

[0012] As shown in Figures 1 to 5, the energy storage device 1 includes a plurality of first energy storage modules 101, a plurality of second energy storage modules 102, 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 modules 101 are arranged side by side in a first direction. In this embodiment, the multiple first power storage modules 101 include six first power storage modules 101. However, the number of first power storage modules 101 is not limited to six. Each first power storage module 101 is formed in a rectangular parallelepiped shape that is elongated in a second direction that is perpendicular to both the first direction and the up-down direction. The first power storage module 101 is an example of a "power storage module" in the present disclosure.

[0014] The multiple second energy storage modules 102 are arranged to face the multiple first energy storage modules 101 in the second direction and to be aligned in the first direction. In this embodiment, the multiple second energy storage modules 102 include six second energy storage modules 102. However, the number of second energy storage modules 102 is not limited to six. The configuration of each second energy storage module 102 is the same as the configuration of the first energy storage stack module. The second energy storage module 102 is an example of "another energy storage module" in the present disclosure.

[0015] Each of the energy storage modules 101 and 102 includes a plurality of energy storage cells 110 , a stack case 120 , and a protective plate 130 .

[0016] The multiple storage cells 110 are arranged, for example, to be aligned in a first direction. Note that the multiple storage cells 110 may also be arranged to be aligned in a second direction. Each storage cell 110 has a shape that extends elongated in the second direction. The multiple storage cells 110 form a storage stack. Each storage cell 110 may be configured as a so-called laminated cell having a laminated exterior body, or may be configured as a so-called prismatic cell formed in a flat rectangular parallelepiped shape. An example of each storage cell 110 is a lithium ion battery. Each storage cell 110 may be configured as an all-solid-state battery using a solid electrolyte.

[0017] The stack case 120 houses a plurality of energy storage cells 110, i.e., an energy storage stack. The stack case 120 is formed in a rectangular parallelepiped shape. As shown in Fig. 5, the stack case 120 has a lower case 122 and a lid 124. The lower case 122 is open upward. The lid 124 closes the opening of the lower case 122. The lid 124 is fixed to the opening of the lower case 122 by welding or the like. A plurality of through holes 124h are formed in the lid 124.

[0018] The protective plate 130 covers the stack case 120. The protective plate 130 is made of a heat-resistant and insulating material. For example, the protective plate 130 is made of mica, which is a natural inorganic mineral solidified by heat pressing. The protective plate 130 is formed with an exhaust port h for discharging gas generated from the energy storage cells 110.

[0019] As shown in Fig. 5, the protective plate 130 has a covering portion 132 and an edge portion 134. The covering portion 132 covers the lid 124 of the stack case 120. The covering portion 132 is formed in a flat plate shape. An exhaust port h is formed in the covering portion 132. The edge portion 134 extends downward from an end of the covering portion 132 in the first direction. The edge portion 134 covers the boundary between the lower case 122 and the lid 124.

[0020] The first bus bar 210 (see FIG. 2 ) connects a pair of first energy storage modules 101 adjacent to each other in the first direction. The first bus bar 210 is routed in a routing space S1 (see FIGS. 3 and 4 ) between the plurality of first energy storage modules 101 and the plurality of second energy storage modules 102.

[0021] The second bus bar 220 (see FIG. 2 ) connects a pair of second power storage modules 102 adjacent to each other in the first direction. The second bus bar 220 is routed in the routing space S1. Note that the first bus bar 210 and the second bus bar 220 are not shown in FIG. 3 .

[0022] The first junction box 310 is disposed in a position facing, in the first direction, a first power storage module 101 that is disposed outermost in the first direction (e.g., on the front side in the longitudinal direction of the vehicle) among the multiple first power storage modules 101. The first junction box 310 houses a relay, a fuse, etc. The first junction box 310 has a first connector 312. The first connector 312 protrudes outward in the first direction.

[0023] The second junction box 320 is disposed at a position facing the second power storage module 102 in the first direction and facing the first junction box 310 at a distance in the second direction. The second junction box 320 houses relays, fuses, and the like. As shown in FIGS. 2 and 3 , 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.

[0024] The cover plate 400 (see FIG. 4 ) covers the first bus bar 210 and the second bus bar 220 from above. The cover plate 400 is disposed between the plurality of first energy storage modules 101 and the plurality of second energy storage modules 102. The cover plate 400 extends along the first direction. The cover plate 400 is formed in a flat plate shape. The cover plate 400 is made of an insulating material. The cover plate 400 is made of, for example, mica, which is a natural inorganic mineral solidified by heat pressing. The cover plate 400 has the function of blocking gas ejected upward from any of the energy storage modules from coming into contact with the bus bars 210, 220. Note that the cover plate 400 is not shown in FIGS. 2 and 3 .

[0025] The case 500 accommodates the plurality of first energy storage modules 101, the plurality of second energy storage modules 102, the first bus bar 210, the second bus bar 220, the first junction box 310, the second junction box 320, and the cover plate 400. The case 500 includes a one-side space S2 formed on one side of the plurality of first energy storage modules 101 and the plurality of second energy storage modules 102 in the first direction. Each of the junction boxes 310, 320 is arranged in this one-side space S2. The case 500 has a lower case 510 and an upper cover 520.

[0026] The lower case 510 is open upward and has a bottom wall 512, a peripheral wall 514, and a partition 516.

[0027] The bottom wall 512 supports the power storage modules 101 and 102 .

[0028] 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 modules 101 and the plurality of second power storage modules 102. The peripheral wall 514 is formed in a substantially rectangular cylindrical shape.

[0029] The peripheral wall 514 includes a side wall 514a formed on the side opposite (the left side in FIG. 3 ) from the side on which the first junction box 310 and the second junction box 320 are disposed, relative to the side on which the first power storage modules 101 and the second power storage modules 102 are disposed. In other words, the side wall 514a faces the power storage modules 101, 102 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.

[0030] The partition 516 separates the plurality of first energy storage modules 101 from the plurality of second energy storage modules 102. 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 FIG. 4 , a wiring space S1 is formed between the partition 516 and the cover plate 400.

[0031] The upper cover 520, together with the lower case 510, accommodates the plurality of first power storage modules 101, the plurality of second power storage modules 102, the first bus bar 210, the second bus bar 220, the first junction box 310, the second junction box 320, and the cover plate 400. The peripheral edge of the upper cover 520 is fixed to the upper end of the peripheral wall 514 by bolts or the like.

[0032] The upper cover 520 has an upper wall 522. The upper wall 522 faces the bottom wall 512. The upper wall 522 covers the plurality of first power storage modules 101, the plurality of second power storage modules 102, the first bus bar 210, the second bus bar 220, the first junction box 310, the second junction box 320, and the cover plate 400.

[0033] 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 FIGS. 3 and 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.

[0034] 4 and 5 , a shielding portion 525 is provided on the inner surface of the upper cover 520. The shielding portion 525 is provided in a portion of the inner surface of the upper cover 520 in front of the power storage modules 101, 102. 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.

[0035] 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. The breathing membrane 700 is disposed on the opposite side of the pressure release valve 600 from the side on which the power storage modules 101 and 102 are disposed. In this embodiment, the breathing membrane 700 is provided on 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. As shown in FIGS. 3 to 5 , the breathing membrane 700 is provided on a portion of the side wall 514a facing the inter-box space S3.

[0036] 5 , the exhaust port h is formed at a position away from the end of the stack case 120 that is closer to the pressure release valve 600. The distance D1 between the breathing membrane 700 and the pressure release valve 600 is smaller than the distance D2 between the exhaust port h and the pressure release valve 600.

[0037] The distance D1 is the length between the center of a through-hole formed in the side wall 514a at a portion facing the breathing membrane 700 and the center of a through-hole formed in the top wall 522 at a portion facing the pressure release valve 600. Here, if multiple breathing membranes 700 are provided on the side wall 514a, the "breathing membrane 700" used as the basis for distance D1 refers to the breathing membrane 700 that is closest to the pressure release valve 600 among all the breathing membranes 700. The distance D2 is the length between the center of a through-hole formed in the top wall 522 at a portion facing the pressure release valve 600 and the portion of the exhaust port h formed in the protective plate 130 that is closest to the pressure release valve 600. Here, if multiple exhaust ports h are formed in the protective plate 130, the "exhaust port h" used as the basis for distance D2 refers to the exhaust port h that is closest to the pressure release valve 600 among all the exhaust ports h.

[0038] As described above, in the energy storage device 1 of this embodiment, the distance D1 between the breathing membrane 700 and the pressure release valve 600 is smaller than the distance D2 between the exhaust port h and the pressure release valve 600. Therefore, after gas has been discharged once through the pressure release valve 600, the air flowing between the breathing membrane 700 and the pressure release valve 600 is prevented from flowing toward the exhaust port h, and the resulting blast generation is prevented.

[0039] Furthermore, if gas is generated from either of the storage modules 101, 102 and air flows into the case 500 through the breathing membrane 700, the air comes into contact with each of the junction boxes 310, 320, thereby preventing the air that has flowed into the case 500 from reaching the storage modules 101, 102 and causing blasts and other problems.

[0040] Modifications of the above embodiment will now be described.

[0041] 6 , each of the power storage modules 101, 102 does not necessarily have to have a protective plate 130. In this case, the boundary between the lower case 122 and the lid 124 forms the exhaust port h. In this example, the distance D2 is the length between the center of a through-hole formed in a portion of the upper wall 522 facing the pressure release valve 600 and the portion of the boundary between the lower case 122 and the lid 124 that is closest to the pressure release valve 600.

[0042] <Second Modification> As shown in Figures 7 and 8, each energy storage cell 110 may be configured as a so-called prismatic cell. In the example shown in Figure 7, the multiple energy storage cells 110 are arranged to be aligned in a first direction, and in the example shown in Figure 8, the multiple energy storage cells 110 are arranged to be aligned in a second direction. Each energy storage cell 110 has a safety valve 112 and a pair of external terminals 114. The safety valve 112 is provided at a position facing the upper wall 522, i.e., on the upper surface of the housing of the energy storage cell 110. The pair of external terminals 114 are provided at positions on either side of the safety valve 112 on the upper surface of the housing of the energy storage cell. A protective plate 130 covers each external terminal 114.

[0043] In this example, distance D2 is the length between the center of the through hole formed in the portion of upper wall 522 facing pressure release valve 600 and the portion of safety valve 112 of storage cell 110 located closest to pressure release valve 600 that is closest to pressure release valve 600.

[0044] <Third Modification> Although not shown in the drawings, the plurality of second power storage modules 102 may be omitted.

[0045] It will be appreciated by those skilled in the art that the exemplary embodiments described above are examples of the following aspects.

[0046] [Aspect 1] An energy storage device comprising: a plurality of energy storage modules arranged in a line along a first direction; a case that houses the plurality of energy storage modules; a pressure release valve provided in the case that releases pressure inside the case; and a breathing membrane provided in the case that adjusts the pressure inside the case by allowing gas to pass between the inside and outside of the case, wherein each of the plurality of energy storage modules has an exhaust port that discharges gas, and the distance between the breathing membrane and the pressure release valve is smaller than the distance between the exhaust port and the pressure release valve.

[0047] In this energy storage device, the distance between the breathing membrane and the pressure release valve is smaller than the distance between the exhaust port and the pressure release valve, which prevents the air flowing between the breathing membrane and the pressure release valve from heading toward the exhaust port and the resulting generation of blasts.

[0048] [Aspect 2] The energy storage device according to Aspect 1, wherein each of the energy storage modules includes: a plurality of energy storage cells; a stack case that houses the plurality of energy storage cells; and a protective plate that is made of a heat-resistant and insulating material and covers the stack case, wherein the exhaust port is formed in the protective plate, and the exhaust port is formed at a position spaced apart from an end of the stack case that is closer to the pressure release valve.

[0049] [Aspect 3] The energy storage device according to Aspect 1, wherein each of the energy storage modules includes a plurality of energy storage cells and a stack case that houses the plurality of energy storage cells, the stack case includes a lower case that opens upward and a lid that closes the opening of the lower case, and the boundary between the lower case and the lid forms the exhaust port.

[0050] [Aspect 4] The energy storage device according to Aspect 1, wherein the case includes an upper wall covering the plurality of energy storage modules, each of the energy storage modules includes a plurality of energy storage cells, and each of the plurality of energy storage cells includes a safety valve provided at a position facing the upper wall, and the safety valve constitutes the exhaust port.

[0051] [Aspect 5] The energy storage device according to any one of Aspects 1 to 4, wherein the case includes a one-side space formed on one side of the plurality of energy storage modules in the first direction, the case includes: a side wall facing the plurality of energy storage modules in the first direction across the one-side space; and a top wall covering the plurality of energy storage modules, the pressure release valve being provided in a portion of the top wall above the one-side space, and the breathing membrane being provided on the side wall.

[0052] In this configuration, when gas is discharged from any of the storage modules, the gas flows toward one of the spaces, where it changes direction upward toward the pressure release valve, thereby reducing the flow rate of the gas discharged from the case.

[0053] Aspect 6 The energy storage device according to Aspect 5, further comprising: a plurality of other energy storage modules that face the plurality of energy storage modules in a second direction that is orthogonal to both the first direction and the up-and-down direction and that are arranged side by side along the first direction; a first junction box that is arranged at a position facing the energy storage modules in the first direction; and a second junction box that faces the other energy storage modules in the first direction and that faces the first junction box in the second direction with a gap between them, wherein the one-side space is formed on one side of the plurality of energy storage modules and the plurality of other energy storage modules in the first direction, the first junction box and the second junction box are arranged in the one-side space, the pressure release valve is provided in a portion of the top wall above an inter-box space between the first junction box and the second junction box, and the breathing membrane is provided in a portion of the side wall that faces the inter-box space.

[0054] In this embodiment, when air flows into the case through the breathing membrane after gas is discharged from the pressure release valve, the air tends to stagnate in the one-side space by coming into contact with each junction box.

[0055] 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, not by the description of the above embodiments, and further includes all modifications within the meaning and scope of the claims.

[0056] 1 Energy storage device, 101 First energy storage module (energy storage module), 102 Second energy storage module (other energy storage module), 110 Energy storage cell, 112 Safety valve, 114 External terminal, 120 Stack case, 122 Lower case, 124 Lid, 130 Protective plate, 132 Covering portion, 134 Edge portion, 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 Peripheral wall, 514a Side wall, 520 Upper cover, 525 Shielding portion, 600 Pressure release valve, 700 Breathing membrane, h Exhaust port, S1 Wiring space, S2 One side space, S3 Inter-box space.

Claims

1. An energy storage device comprising: a plurality of energy storage modules arranged in a line along a first direction; a case that houses the plurality of energy storage modules; 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 each of the plurality of energy storage modules has an exhaust port for discharging gas, and the distance between the breathing membrane and the pressure release valve is shorter than the distance between the exhaust port and the pressure release valve.

2. The energy storage device according to claim 1, wherein each of the energy storage modules comprises: a plurality of energy storage cells; a stack case that houses the plurality of energy storage cells; and a protective plate that is made of a heat-resistant and insulating material and covers the stack case; the protective plate has the exhaust port formed therein; and the exhaust port is formed at a position spaced apart from the end of the stack case that is closer to the pressure release valve.

3. The energy storage device according to claim 1, wherein each of the energy storage modules comprises a plurality of energy storage cells and a stack case that houses the plurality of energy storage cells, the stack case having a lower case that opens upward and a lid that closes the opening of the lower case, and the boundary between the lower case and the lid forms the exhaust port.

4. The energy storage device according to claim 1, wherein the case includes an upper wall that covers the plurality of energy storage modules, each of the energy storage modules includes a plurality of energy storage cells, and each of the plurality of energy storage cells includes a safety valve provided at a position opposite the upper wall, and the safety valve constitutes the exhaust port.

5. The energy storage device described in claim 1, wherein the case includes a one-side space formed on one side of the plurality of energy storage modules in the first direction, the case includes: a side wall facing the plurality of energy storage modules in the first direction across the one-side space; and an upper wall covering the plurality of energy storage modules, the pressure release valve being provided in a portion of the upper wall above the one-side space, and the breathing membrane being provided on the side wall.

6. The energy storage device according to claim 5, further comprising: a plurality of other energy storage modules that face the plurality of energy storage modules in a second direction that is perpendicular to both the first direction and the up-and-down direction and that are arranged side by side along the first direction; a first junction box that is arranged at a position facing the energy storage modules in the first direction; and a second junction box that faces the other energy storage modules in the first direction and that faces the first junction box in the second direction with a gap between them, wherein the one-side space is formed on one side of the plurality of energy storage modules and the plurality of other energy storage modules in the first direction, the first junction box and the second junction box are arranged in the one-side space, the pressure release valve is provided in a portion of the upper wall above the inter-box space between the first junction box and the second junction box, and the breathing membrane is provided in a portion of the side wall that faces the inter-box space.

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