Energy storage device

Abstract

To provide an energy storage device capable of suppressing heat transfer from a heat-generating energy storage cell to an adjacent energy storage cell. [Solution] The energy storage device 10 comprises a plurality of energy storage cells 100, a bottom wall 212, a panel member 230, and a pair of restraining parts 240. A safety valve SV is provided on the lower surface of each energy storage cell 100. The bottom wall 212 has a plurality of through holes h1 and an insertion hole h2 through which at least one of the pair of restraining parts is inserted. At least one of the pair of restraining parts 240 includes a base portion 242 located in the exhaust path S. The pair of restraining parts 240 are configured to reduce the restraining force that restrains the plurality of energy storage cells when the temperature of the base portion 242 is above a reference value.

Description

Technical Field

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[0001] The present disclosure relates to a power storage device.

Background Art

[0002] For example, Japanese Unexamined Patent Application Publication No. 2023-126584 discloses a battery including a plurality of cells, a case that houses the plurality of cells, a protective member that protects the bottom portion of the case, and a cover. Each cell has a box that houses an electrode assembly. A relief mechanism is provided on the bottom surface of the box. The discharge product discharged from the relief mechanism flows into a collection cavity formed between the bottom portion of the case and the protective member.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the battery described in Japanese Unexamined Patent Application Publication No. 2023-126584, when a cell generates heat due to a short circuit or the like occurring in the electrode assembly, it may be required to reduce the amount of heat transferred from the heated cell to an adjacent cell.

[0005] An object of the present disclosure is to provide a power storage device capable of suppressing heat transfer from a heated power storage cell to an adjacent power storage cell.

Means for Solving the Problems

[0006] A power storage device according to one aspect of the present disclosure comprises a plurality of power storage cells arranged in one direction, a bottom wall positioned below the plurality of power storage cells, a panel member provided below the bottom wall and together with the bottom wall defining a smoke exhaust path, and a pair of restraining parts that restrain the plurality of power storage cells from both sides of the plurality of power storage cells in the one direction, wherein a safety valve is provided on the lower surface of each of the plurality of power storage cells, the bottom wall has a plurality of through holes, each positioned opposite to each of the safety valves, and an insertion hole for inserting at least one of the pair of restraining parts, at least one of the pair of restraining parts includes a base positioned in the smoke exhaust path, and the pair of restraining parts is configured to reduce the restraining force that restrains the plurality of power storage cells when the temperature of the base is above a reference value. [Effects of the Invention]

[0007] According to this disclosure, it is possible to provide an energy storage device that can suppress the transfer of heat from a heat-generating energy storage cell to an adjacent energy storage cell. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic perspective view of an energy storage device in one embodiment of the present disclosure. [Figure 2] This is a schematic plan view showing the power storage device with the upper cover removed. [Figure 3] This is a cross-sectional view taken along line III-III in Figure 2. [Figure 4] This is a schematic cross-sectional view showing a modified example of the restraint portion. [Modes for carrying out the invention]

[0009] Embodiments of this disclosure will be described with reference to the drawings. In the drawings referred to below, the same or equivalent components are given the same number.

[0010] Figure 1 is a schematic perspective view showing an energy storage device in one embodiment of the present disclosure. Figure 2 is a schematic plan view showing the energy storage device with the upper cover removed. Figure 3 is a cross-sectional view taken along line III-III in Figure 2.

[0011] In this embodiment, the energy storage device 10 is mounted, for example, on the underside of a vehicle. Examples of vehicles include hybrid electric vehicles, plug-in hybrid electric vehicles, and battery electric vehicles.

[0012] As shown in Figures 1 to 3, the energy storage device 10 comprises six energy storage stacks 11 to 16, a housing 200, protective members 280, equipment 300, equipment cooler 350, and refrigerant piping 400. Note that the number of energy storage stacks is not limited to six.

[0013] Each energy storage stack 11-16 is formed in a rectangular parallelepiped shape that is elongated in the first direction DR1. As shown in Figure 2, the six energy storage stacks 11-16 are arranged to line up along a second direction DR2 that is perpendicular to both the first direction DR1 and the vertical direction. In this embodiment, the first direction DR1 corresponds to the longitudinal direction of the vehicle, and the second direction DR2 corresponds to the left-right direction (width direction) of the vehicle. Each energy storage stack 11-16 contains at least one energy storage cell 100. In this embodiment, each energy storage stack 11-16 contains a plurality of energy storage cells 100 and a plurality of cooling plates 150.

[0014] Multiple energy storage cells 100 are arranged in a line along a first direction DR1. As shown in Figure 3, each energy storage cell 100 has an electrode body 112, a cell case 114, and a pair of external terminals 116.

[0015] The electrode body 112 may be formed of a wound body in which a positive electrode sheet and a negative electrode sheet are wound with a separator interposed therebetween, or may be formed of a laminate in which a positive electrode sheet and a negative electrode sheet are laminated with a separator interposed therebetween. The electrode body 112 is formed in a shape that is long in the second direction DR2.

[0016] The cell case 114 houses the electrode body 112. The cell case 114 is formed in a rectangular parallelepiped shape. The cell case 114 is made of a metal such as aluminum. A safety valve SV is provided on the lower surface of the cell case 114. 〈0000078〉 〈0000079〉 〈0000080〉 A pair of external terminals 116 are provided on the upper surface of the cell case 114. The pair of external terminals 116 are provided at positions spaced apart from each other in the width direction of the cell case 114. Note that the width direction of the cell case 114 corresponds to the second direction DR2. 〈0000081〉 〈0000082〉 〈0000083〉 As shown in FIG. 3, each cooling plate 150 is disposed between a pair of power storage cells 100 adjacent to each other in the first direction DR1. Each cooling plate 150 is formed in a flat plate shape that is long in the second direction DR2. Each cooling plate 150 has a flow path (not shown) through which a refrigerant flows along the second direction DR2. 〈0000084〉 〈0000085〉 〈0000086〉 The housing 200 houses six power storage stacks 11 to 16. As shown in FIGS. 1 to 3, the housing 200 includes a lower case 210, an upper cover 220, a panel member 230, and a pair of restraint portions 240. 〈0000087〉 〈0000088〉 〈0000089〉 The lower case 210 is open upward. The lower case 210 may be formed of a metal such as aluminum. The lower case 210 has a bottom wall 212 and a peripheral wall 214. 〈0000090〉 〈0000091〉 〈0000092〉 The bottom wall 212 is located below each of the power storage stacks 11 to 16. In the present embodiment, the bottom wall is formed in a hollow shape. The bottom wall 212 may be formed by extrusion molding. However, the bottom wall 212 may be formed in a solid and flat plate shape. 〈0000093〉 〈0000094〉 As shown in FIG. 3, a plurality of through-holes h1 and a pair of insertion holes h2 are formed in the bottom wall 212. In FIG. 3, only one of the pair of insertion holes h2 is shown.

[0023] Each through-hole h1 is provided at a position facing the safety valve SV. The length of each through-hole h1 in the first direction DR1 is larger than the length of the safety valve SV in the first direction DR1.

[0024] Each insertion hole h2 is a through-hole for inserting the restraint portion 240. Each insertion hole h2 extends in the second direction DR2. One of the pair of insertion holes h2 may be omitted.

[0025] The protective member 280 is provided on the bottom wall 212. As shown in FIG. 3, the protective member 280 has a plurality of heat insulating members 282 and a holding sheet 284.

[0026] Each heat insulating member 282 is provided in the through-hole h1. Each heat insulating member 282 has a shape that closes the through-hole h1. In the present embodiment, the upper surface of each heat insulating member 282 is set flush with the upper surface of the bottom wall 212. Each heat insulating member 282 has a function of protecting each power storage cell 100 from the gas discharged from the safety valve SV. Each heat insulating member 282 is made of, for example, mica obtained by solidifying natural inorganic minerals by hot pressing.

[0027] The holding sheet 284 holds the plurality of heat insulating members 282. Each heat insulating member 282 may be adhered to the back surface of the holding sheet 284. The holding sheet 284 is made of, for example, polypropylene.​​​​​​​The front wall 214a is formed on one side (the left side in Figure 2) of each energy storage stack 11-16 in the first direction DR1. The front wall 214a extends in the second direction DR2. In this embodiment, one side in the first direction DR1 corresponds to the front side in the longitudinal direction of the vehicle.

[0030] A pair of side walls 214b are spaced apart from each other and face each other in the second direction DR2. Each side wall 214b extends in the first direction DR1. One end (front end) of each side wall 214b in the first direction DR1 is connected to the front wall 214a.

[0031] The upper cover 220 is positioned above each of the energy storage stacks 11-16. The upper cover 220, together with the lower case 210, houses the six energy storage stacks 11-16. Specifically, the upper cover 220, together with the lower case 210, houses the six energy storage stacks 11-16 in a sealed state. The peripheral edge of the upper cover 220 is connected to the upper end of the peripheral wall 214 by bolts or the like via a sealing member.

[0032] The panel member 230 is located below the lower case 210. The panel member 230 has the function of protecting the bottom wall 212 of the lower case 210. The panel member 230 may be formed in a flat plate shape. The peripheral edge of the panel member 230 is connected to the lower surface of the lower case 210 via a sealing member.

[0033] As shown in Figure 3, a space S is formed between the panel member 230 and the bottom wall 212. Each space S functions as a smoke exhaust path (hereinafter referred to as "smoke exhaust path S"). The smoke exhaust path S is a path for discharging the gas discharged from the safety valve SV of the energy storage cell 100 to the outside of the housing 200.

[0034] As shown in Figures 2 and 3, a smoke exhaust duct section 218 is formed in the peripheral wall 214. The smoke exhaust duct section 218 extends upward from the bottom wall 212. The smoke exhaust duct section 218 guides the gas upward from the smoke exhaust path S. An explosion-proof valve EV is provided at the downstream end of the smoke exhaust duct section 218. The explosion-proof valve EV releases the pressure inside the housing 200. The explosion-proof valve EV opens when the pressure inside the housing 200 exceeds a reference value. The explosion-proof valve EV is composed of a check valve. As shown in Figure 3, when gas is discharged from any of the energy storage cells 100, the gas spreads in the first direction DR1 through the smoke exhaust path S and is discharged outside the housing 200 through the smoke exhaust duct section 218 and the explosion-proof valve EV.

[0035] A pair of restraining parts 240 restrain a plurality of energy storage cells 100 from both sides in the first direction DR1. More specifically, the pair of restraining parts 240 restrain each energy storage stack 11-16 from both sides in the first direction DR1. Each restraining part 240 extends in the second direction DR2. As shown in Figure 2, the pair of restraining parts 240 divide the space enclosed by the bottom wall 212 and the peripheral wall 214 into the space where each energy storage stack 11-16 is arranged and the rest of the space. The end of the restraining part 240 formed on one side (front side) in the first direction DR1 in the second direction DR2 is separated from each side wall 214b. The end of the restraining part 240 formed on the other side (rear side) in the first direction DR1 in the second direction DR2 is connected to each side wall 214b.

[0036] As shown in Figure 3, at least one of the pair of restraint portions 240 has a base portion 242 and a restraint portion body 244. In this embodiment, each of the pair of restraint portions 240 has a base portion 242 and a restraint portion body 244.

[0037] The base portion 242 is positioned in the smoke exhaust path S. The lower surface of the base portion 242 may be in contact with the panel member 230. The upper surface of the base portion 242 may be located below the lower surface of the bottom wall 212, or it may be located within the insertion hole h2.

[0038] The restraint body 244 extends upward from the base 242. The lower part of the restraint body 244 is inserted into the insertion hole h2. The pair of restraint body 244s exert a restraining force on a plurality of energy storage cells 100. The restraint body 244 is made of a metal such as aluminum. The restraint body 244 may be formed in a hollow shape. The upper surface of the restraint body 244 may be formed flush with the upper surface of the cell case 114, or it may be formed at a position higher than the upper surface of the cell case 114, or it may be formed at a position lower than the upper surface of the cell case 114. A spacer (not shown) may be provided between the energy storage cell 100 located at the end in the first direction DR1 and the restraint body 244.

[0039] The pair of restraining parts 240 are configured to reduce the restraining force that restrains the multiple energy storage cells 100 when the temperature of the base 242 exceeds a reference value. In this embodiment, the base 242 is made of a material that softens when the temperature of the base 242 exceeds a reference value. The base 242 is made of, for example, a synthetic resin whose softening point is below a reference value.

[0040] As shown in Figure 3, the energy storage device 10 may include a surrounding member 290. The surrounding member 290 is provided between the lower surface of the energy storage cell 100 and the upper surface of the bottom wall 212. The surrounding member 290 has a shape that surrounds the through hole h1. In this embodiment, the surrounding member 290 is provided between the bottom surface of the cell case 114 and the retaining sheet 284. The lower surface of the surrounding member 290 is in contact with the retaining sheet 284 located on the upper surface of the bottom wall 212. The upper surface of the surrounding member 290 may be in contact with the bottom surface of the cell case 114. The surrounding member 290 is made of resin, metal, or the like. The surrounding member 290 may also be in contact with the underside of the cooling plate 150.

[0041] The equipment 300 is housed in the enclosure 200. As shown in Figure 2, the equipment 300 is located in the space formed between the partition wall 216 and the peripheral wall 214, which are located on the other side of the lower case 210 in the first direction DR1, i.e., on the other side (rear side) in the first direction DR1. The equipment 300 may include a junction box. The equipment 300 may include relays, control equipment, etc.

[0042] The equipment cooler 350 cools the equipment 300. As shown in Figures 2 and 3, the equipment cooler 350 is provided between the bottom wall 212 and the equipment 300. A thermally conductive adhesive 900 may be provided between the equipment cooler 350 and the bottom wall 212.

[0043] The refrigerant piping 400 is routed within the housing 200. The refrigerant piping 400 is connected to each cooling plate 150 and the equipment cooler 350. As shown in Figures 1 and 2, the front wall 214a of the peripheral wall 214 is provided with an inlet port 181 and an outlet port 182. The refrigerant piping 400 is connected to the inlet port 181 and the outlet port 182. Therefore, the refrigerant (water, oil, etc.) supplied from the inlet port 181 flows through the refrigerant piping 400 to each cooling plate 150 and the equipment cooler 350, cools each energy storage cell 100 and equipment 300, and then flows out through the refrigerant piping 400 from the outlet port 182.

[0044] As shown in Figure 2, the refrigerant piping 400 includes an upstream pipe 410 and a downstream pipe 420.

[0045] The upstream end of the upstream piping 410 is connected to the inlet port 181. The downstream end of the upstream piping 410 is connected to one end of the equipment cooler 350 in the second direction DR2. The upstream piping 410 is routed to pass between the front wall 214a and the restraint portion 240 formed on one side in the first direction DR1, and between the energy storage stack 11 and the side wall 214b located on one side in the second direction DR2. The upstream piping 410 is connected to one end of each cooling plate 150 in the second direction DR2.

[0046] The upstream end of the downstream pipe 420 is connected to the other end of the equipment cooler 350 in the second direction DR2. The downstream end of the downstream pipe 420 is connected to the outflow port 182. The downstream pipe 420 is routed to pass between the front wall 214a and the restraint portion 240 formed on one side in the first direction DR1, and between the energy storage stack 16 and the side wall 214b located on the other side in the second direction DR2. The downstream pipe 420 is connected to the other end of each cooling plate 150 in the second direction DR2.

[0047] In the energy storage device 10 described above, if a short circuit or the like causes discharge from the safety valve SV downward in any of the energy storage cells 100, the discharge collides with the retaining sheet 284 and the heat insulating member 282. As a result, the retaining sheet 284 melts and the heat insulating member 282 ruptures, and the discharge containing the contents of the energy storage cell 100 (so-called debris) flows into the exhaust gas path S through the through hole h1. Subsequently, the gas contained in the discharge spreads through the exhaust gas path S.

[0048] At this time, the base 242 is heated when the gas comes into contact with it. As a result, the temperature of the base 242 exceeds the reference value, reducing the restraining force of the pair of restraining parts 240 on the multiple energy storage cells 100. Therefore, the transfer of heat from the heated energy storage cell 100 to the energy storage cell 100 adjacent to that energy storage cell 100 is suppressed.

[0049] Subsequently, the gas is discharged from the housing 200 through the explosion-proof valve EV, as shown in Figure 3. Therefore, the adhesion of contents from the energy storage cell 100 to the external terminals 116, etc., is suppressed.

[0050] Modifications of the above embodiment will be described below.

[0051] As shown in Figure 4, the energy storage device 10 may further include restraint bands 250. In this example, each restraint portion 240 is made of a restraint plate made of metal (hereinafter referred to as "restraint plate 240"). The base portion 242 of the restraint plate 240 is located in the exhaust path S.

[0052] The restraint band 250 connects a pair of restraint plates 240. The restraint band 250 is made of metal. The restraint band 250 is in thermal contact with each of the pair of restraint plates 240. The restraint band 250 expands to reduce its restraining force when its temperature exceeds a reference value. In the example shown in Figure 4, the restraint band 250 is positioned above each of the energy storage stacks 11-16. As shown in Figure 4, the restraint band 250 has a band body 252 and a fixing portion 254.

[0053] The band body 252 is formed in a flat plate shape. The band body 252 is positioned on the upper surface of each cell case 114 in the area between the pair of external terminals 116. The band body 252 may be bonded to the upper surface of the cell case 114. The thickness (vertical dimension) of the band body 252 is preferably equal to or less than the sum of the thickness of each external terminal 116 and the thickness of the bus bar (not shown) connected to the external terminal 116. The band body 252 extends from one of the pair of restraint plates 240 to the other. From the viewpoint of increasing the bending rigidity of the band body 252, a bead (not shown) extending in the first direction DR1 may be formed on the band body 252. Alternatively, a convex ridge (not shown) extending in the first direction DR1 may be formed on at least one of the upper and lower surfaces of the band body 252.

[0054] The fixing portion 254 is connected to the end of the band body 252 in the first direction DR1. As shown in Figure 4, the fixing portion 254 is fixed to the outer surface of each restraint plate 240 in the first direction DR1 by fastening members (not shown) or the like.

[0055] The energy storage device 10 may further include an intervening member 370. The intervening member 370 is interposed between the band body 252 and the upper cover 220. Multiple intervening members 370 may be arranged at intervals in the first direction DR1. Alternatively, a single intervening member 370 may be arranged between the band body 252 and the upper cover 220. The intervening member 370 is made of resin, metal, or the like.

[0056] In this embodiment, when gas flows into the exhaust path S, the heat of the gas is transferred from the base 242 to the restraining band 250 via the restraining plate 240. When the temperature of the restraining band 250 exceeds a reference value, the restraining band 250 expands, causing the restraining force of the pair of restraining plates 240 to decrease.

[0057] Furthermore, in this embodiment, even if the internal pressure of the cell case 114 rises due to a short circuit or the like, the band body 252 is adhered to the upper surface of the cell case 114, so that the upper surface of the cell case 114 does not burst when the internal pressure of the cell case 114 rises. As a result, the discharged material from the energy storage cell 100 is effectively discharged downward from the safety valve SV provided on the lower surface of the cell case 114.

[0058] Those skilled in the art will understand that the exemplary embodiments described above are specific examples of the following embodiments.

[0059] [Aspect 1] Multiple energy storage cells arranged in one direction, A bottom wall positioned below the plurality of energy storage cells, A panel member provided below the bottom wall, which together with the bottom wall defines the smoke exhaust path, The system comprises a pair of restraining parts that restrain the plurality of energy storage cells from both sides of the plurality of energy storage cells in the aforementioned one direction, A safety valve is provided on the lower surface of each of the aforementioned plurality of energy storage cells. The aforementioned bottom wall is Multiple through holes are provided, each positioned opposite to the respective safety valve, It has an insertion hole through which at least one of the pair of restraining parts is inserted, At least one of the pair of restraining parts includes a base that is positioned in the smoke exhaust path, An energy storage device in which the pair of restraining parts are configured to reduce the restraining force that restrains the plurality of energy storage cells when the temperature of the base is above a reference value.

[0060] In this energy storage device, when gas discharged from the safety valve of an energy storage cell and flowing into the exhaust path through a through-hole expands in the exhaust path, the gas comes into contact with the base, causing the base to heat up. As a result, the temperature of the base exceeds a standard value, reducing the restraining force between multiple energy storage cells by a pair of restraining parts. Therefore, heat transfer from the heated energy storage cell to adjacent energy storage cells is suppressed.

[0061] [Aspect 2] One of the pair of restraining parts further has a restraining part body extending upward from the base, The restraining body, together with the other of the pair of restraining parts, applies the restraining force to the plurality of energy storage cells. The energy storage device according to embodiment 1, wherein the base is made of a material that softens when the temperature of the base is above the reference value.

[0062] In this embodiment, when the gas flowing into the exhaust path comes into contact with the base and the temperature of the base exceeds a reference value, the base softens, and the restraining force of the restraining part body decreases.

[0063] [Aspect 3] The restraint band is in thermal contact with each of the pair of restraint parts and further connects the pair of restraint parts together. At least one of the pair of restraint portions includes a restraint plate including the base portion, The energy storage device according to embodiment 1, wherein the restraining band expands to reduce the restraining force when the temperature of the restraining band exceeds the reference value.

[0064] In this embodiment, when gas flows into the exhaust gas path, heat is transferred from the base to the restraining band via the restraining plate, causing the restraining band to expand and thus reducing the restraining force.

[0065] [Aspect 4] An upper cover positioned above the aforementioned plurality of energy storage cells, The energy storage device according to embodiment 3, further comprising an intervening member interposed between the restraint band and the upper cover.

[0066] In this embodiment, the restraint band is pressed down from above by the intervening member and the upper cover, thereby suppressing the rupture of the upper surface of the energy storage cell when the internal pressure of the energy storage cell rises.

[0067] It should be noted that the embodiments disclosed herein are illustrative in all respects and not restrictive. The scope of this disclosure is defined by the claims rather than the description of the embodiments above, and includes all modifications within the meaning and scope equivalent to the claims. [Explanation of symbols]

[0068] 10 Energy storage device, 11-16 Energy storage stack, 100 Energy storage cell, 112 Electrode body, 114 Cell case, 116 External terminal, 200 Housing, 210 Lower case, 212 Bottom wall, 214 Peripheral wall, 218 Smoke exhaust duct section, 220 Upper cover, 240 Restraint section (restraint plate), 242 Base, 244 Restraint section body, 250 Restraint band, 280 Protective member, 282 Heat insulation member, 284 Retaining sheet, 300 Equipment, 350 Equipment cooler, 370 Intervening member, 400 Refrigerant piping, 410 Upstream piping, 420 Downstream piping, 900 Thermal conductive adhesive, EV Explosion-proof valve, h1 Through hole, h2 Insertion hole, S Space (smoke exhaust path), SV Safety valve.

Claims

1. Multiple energy storage cells arranged in one direction, A bottom wall positioned below the plurality of energy storage cells, A panel member provided below the bottom wall, which together with the bottom wall defines the smoke exhaust path, The system comprises a pair of restraining parts that restrain the plurality of energy storage cells from both sides of the plurality of energy storage cells in the aforementioned one direction, A safety valve is provided on the lower surface of each of the aforementioned plurality of energy storage cells. The aforementioned bottom wall is Multiple through holes are provided, each positioned opposite to the respective safety valve, It has an insertion hole through which at least one of the pair of restraining parts is inserted, At least one of the pair of restraining parts includes a base that is positioned in the smoke exhaust path, An energy storage device in which the pair of restraining parts are configured to reduce the restraining force that restrains the plurality of energy storage cells when the temperature of the base is above a reference value.

2. One of the pair of restraining parts further has a restraining part body extending upward from the base, The restraining body, together with the other of the pair of restraining parts, applies the restraining force to the plurality of energy storage cells. The energy storage device according to claim 1, wherein the base is made of a material that softens when the temperature of the base is above the reference value.

3. The restraint band is in thermal contact with each of the pair of restraint parts and further connects the pair of restraint parts together. At least one of the pair of restraint portions includes a restraint plate including the base portion, The energy storage device according to claim 1, wherein the restraining band expands to reduce the restraining force when the temperature of the restraining band exceeds the reference value.

4. An upper cover positioned above the aforementioned plurality of energy storage cells, The energy storage device according to claim 3, further comprising an intervening member interposed between the restraint band and the upper cover.

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