Electricity storage device

Abstract

The invention relates to a power storage device. A power storage device is provided with a plurality of power storage cells, a bottom wall, a panel member, and a pair of constraining parts. The lower surface of each storage cell is provided with a safety valve. The bottom wall has a plurality of through holes and an insertion hole into which at least one of the pair of restraining parts is inserted. At least one of the pair of constraining portions includes a base portion disposed in the smoke discharge path. The pair of constraining parts is configured so as to reduce a constraining force that constrains the plurality of storage cells when the temperature of the base part is equal to or greater than a reference value.

Description

Technical Field

[0001] This disclosure relates to energy storage devices. Background Technology

[0002] For example, Japanese Patent Application Publication No. 2023-126584 discloses a battery having multiple battery cells, a housing for housing the multiple battery cells, a protective member for the bottom portion of the housing, and a cover. Each battery cell has a box for housing electrode assemblies. An overflow mechanism is provided on the bottom surface of the box. The discharge material discharged from the overflow mechanism flows into a collection cavity formed between the bottom portion of the housing and the protective member.

[0003] In the battery described in Japanese Patent Application Publication No. 2023-126584, when the cell heats up due to a short circuit or other reasons caused by the electrode assembly, it is sometimes necessary to reduce the amount of heat transferred from the heated cell to the cells adjacent to it. Summary of the Invention

[0004] The purpose of this disclosure is to provide an energy storage device capable of suppressing heat transfer from a heated energy storage cell to an adjacent energy storage cell.

[0005] One aspect of this disclosure relates to an energy storage device comprising: a plurality of energy storage cells arranged in one direction; a bottom wall disposed below the plurality of energy storage cells; a panel component disposed below the bottom wall and defining a smoke exhaust path together with the bottom wall; and a pair of restraining portions restraining the plurality of energy storage cells from both sides of the plurality of energy storage cells in the one direction, wherein a safety valve is provided on the lower surface of each plurality of energy storage cells, the bottom wall having: a plurality of through holes disposed opposite to each of the safety valves; and an insertion hole for insertion of at least one of the pair of restraining portions, at least one of the pair of restraining portions including a base disposed in the smoke exhaust path, the pair of restraining portions being configured to reduce the restraining force on the plurality of energy storage cells when the temperature of the base is above a reference value.

[0006] According to this disclosure, it is possible to provide an energy storage device that can suppress heat transfer from a heated energy storage cell to an energy storage cell adjacent to the heated energy storage cell. Attached Figure Description

[0007] The features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, wherein the same symbols denote the same elements, and wherein:

[0008] Figure 1 This is a perspective view schematically illustrating an embodiment of the energy storage device of the present disclosure.

[0009] Figure 2 It is a top view that roughly shows the state of the energy storage device with the top cover removed.

[0010] Figure 3 yes Figure 2 A cross-sectional view at line III-III.

[0011] Figure 4 It is a cross-sectional view that roughly represents a modified example of the constraint part. Detailed Implementation

[0012] Embodiments of this disclosure will be described with reference to the accompanying drawings. In the drawings referred to below, the same or equivalent parts are labeled with the same reference numerals.

[0013] Figure 1 This is a perspective view schematically illustrating an embodiment of the energy storage device of the present disclosure. Figure 2 It is a top view that roughly shows the state of the energy storage device with the top cover removed. Figure 3 yes Figure 2 A cross-sectional view at line III-III.

[0014] In this embodiment, the energy storage device 10 is mounted, for example, on the lower part of the vehicle. Examples of vehicles include hybrid electric vehicles, plug-in hybrid electric vehicles, and battery electric vehicles.

[0015] like Figures 1 to 3 As shown, the energy storage device 10 includes six energy storage stacks 11 to 16, a frame 200, protective components 280, equipment 300, equipment cooler 350, and refrigerant piping 400. Furthermore, the number of energy storage stacks is not limited to six.

[0016] Each of the energy storage stacks 11 to 16 is formed into a cuboid shape with a length DR1 in the first direction. For example... Figure 2 As shown, six battery stacks 11-16 are arranged along a second direction DR2, which is orthogonal to both the first direction DR1 and the vertical direction. In this embodiment, the first direction DR1 corresponds to the front-rear direction of the vehicle, and the second direction DR2 corresponds to the left-right direction (width direction) of the vehicle. Each battery stack 11-16 includes at least one battery cell 100. In this embodiment, each battery stack 11-16 includes multiple battery cells 100 and multiple cooling plates 150.

[0017] Multiple battery cells 100 are arranged in a manner that follows a first direction DR1. For example... Figure 3 As shown, each battery cell 100 has an electrode body 112, a cell housing 114, and a pair of external terminals 116.

[0018] The electrode body 112 can be formed by winding a positive electrode and a negative electrode with a separator in between, or by stacking a positive electrode and a negative electrode with a separator in between. The electrode body 112 is formed in a shape that is longer in the second direction DR2.

[0019] The cell housing 114 houses the electrode body 112. The cell housing 114 is formed in a cuboid shape. The cell housing 114 is made of a metal such as aluminum. A safety valve SV is provided on the lower surface of the cell housing 114.

[0020] A pair of external terminals 116 are disposed on the upper surface of the cell housing 114. The pair of external terminals 116 are disposed at positions that are separated from each other in the width direction of the cell housing 114. The width direction of the cell housing 114 corresponds to the second direction DR2.

[0021] like Figure 3 As shown, each cooling plate 150 is disposed between a pair of adjacent battery cells 100 in the first direction DR1. Each cooling plate 150 is formed as a flat plate elongated in the second direction DR2. Each cooling plate 150 has a flow path (not shown) for refrigerant to flow along the second direction DR2.

[0022] The 200mm frame can accommodate 6 battery packs (11-16mm). Figures 1 to 3 As shown, the frame 200 has a lower housing 210, an upper cover 220, a panel component 230, and a pair of restraints 240.

[0023] The lower housing 210 opens upwards. The lower housing 210 may be formed of a metal such as aluminum. The lower housing 210 has a bottom wall 212 and a peripheral wall 214.

[0024] The bottom wall 212 is located below each of the battery stacks 11 to 16. In this embodiment, the bottom wall 212 is hollow. The bottom wall 212 can be formed by extrusion molding. However, the bottom wall 212 can also be formed as a solid and flat plate.

[0025] like Figure 3 As shown, multiple through holes h1 and a pair of insertion holes h2 are formed in the bottom wall 212. Among them, in Figure 3 Only one of the two through holes h2 is shown in the image.

[0026] Each through hole h1 is positioned opposite the safety valve SV. The length of each through hole h1 on the first direction DR1 is greater than the length of the safety valve SV on the first direction DR1.

[0027] Each through hole h2 is a through hole for inserting the restraint part 240. Each through hole h2 extends along the second direction DR2. Alternatively, one of a pair of through holes h2 may be omitted.

[0028] The protective component 280 is mounted on the bottom wall 212. For example... Figure 3 As shown, the protective component 280 has multiple heat insulation components 282 and retaining plates 284.

[0029] Each heat insulation component 282 is disposed within the through hole h1. Each heat insulation component 282 has a shape that closes the through hole h1. In this embodiment, the upper surface of each heat insulation component 282 is configured to be coplanar with the upper surface of the bottom wall 212. Each heat insulation component 282 has the function of protecting each battery cell 100 from the gas discharged from the safety valve SV. Each heat insulation component 282 is, for example, made of mica, which is formed by fixing natural inorganic minerals through hot pressing.

[0030] The retaining sheet 284 holds multiple heat-insulating components 282. Each heat-insulating component 282 may also be bonded to the back of the retaining sheet 284. The retaining sheet 284 is made of, for example, polypropylene.

[0031] The peripheral wall 214 rises from the periphery of the bottom wall 212. The peripheral wall 214 has a shape that surrounds each of the battery packs 11 to 16. The peripheral wall 214 may be hollow. The peripheral wall 214 has a front wall 214a and a pair of side walls 214b.

[0032] The front wall 214a is formed on one side of each of the energy storage stacks 11 to 16 in the first direction DR1. Figure 2 (Left side of the vehicle). The front wall 214a extends along the second direction DR2. In this embodiment, one side on the first direction DR1 corresponds to the front side in the longitudinal direction of the vehicle.

[0033] A pair of sidewalls 214b are spaced apart from each other in the second direction DR2. Each sidewall 214b extends along the first direction DR1. One end (front end) of each sidewall 214b in the first direction DR1 is connected to the front wall 214a.

[0034] The upper cover 220 is positioned above each of the battery stacks 11 to 16. The upper cover 220, together with the lower housing 210, houses the six battery stacks 11 to 16. Specifically, the upper cover 220 and the lower housing 210 house the six battery stacks 11 to 16 in a sealed state. The periphery of the upper cover 220 is connected to the upper end of the peripheral wall 214 via a sealing component and bolts or the like.

[0035] The panel component 230 is disposed below the lower housing 210. The panel component 230 functions to protect the bottom wall 212 of the lower housing 210. The panel component 230 may be formed in the shape of a flat plate. The periphery of the panel component 230 is connected to the lower surface of the lower housing 210 via a sealing member.

[0036] like Figure 3As shown, a space S is formed between the panel component 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 battery cell 100 to the outside of the frame 200.

[0037] like Figure 2 and Figure 3 As shown, 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 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 frame 200. The explosion-proof valve EV opens when the pressure inside the frame 200 reaches a reference value. The explosion-proof valve EV is composed of a check valve. Figure 3 As shown, when gas is discharged from any of the battery cells 100, the gas extends in the first direction DR1 through the exhaust path S and is discharged to the outside of the frame 200 through the exhaust pipe section 218 and the explosion-proof valve EV.

[0038] A pair of constraint portions 240 constrain the plurality of energy storage cells 100 from both sides of the plurality of energy storage cells 100 along the first direction DR1. More specifically, the pair of constraint portions 240 constrain each energy storage stack 11 to 16 from both sides of the first direction DR1. Each constraint portion 240 extends along the second direction DR2. Figure 2 As shown, a pair of constraint portions 240 divide the space surrounded by the bottom wall 212 and the peripheral wall 214 into a space for arranging each of the battery stacks 11 to 16 and other spaces. The end of the constraint portion 240 formed on one side (front side) of the first direction DR1 on the second direction DR2 is separated from each side wall 214b. The end of the constraint portion 240 formed on the other side (rear side) of the first direction DR1 on the second direction DR2 is connected to each side wall 214b.

[0039] like Figure 3 As shown, at least one of the pair of constraint portions 240 has a base 242 and a constraint portion body 244. In this embodiment, the pair of constraint portions 240 each has a base 242 and a constraint portion body 244.

[0040] The base 242 is disposed in the smoke exhaust path S. The lower surface of the base 242 may be in contact with the panel component 230. The upper surface of the base 242 may be located below the lower surface of the bottom wall 212, or it may be located within the through hole h2.

[0041] 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. A pair of restraint bodies 244 apply restraint force to a plurality of battery cells 100. The restraint body 244 is made of a metal such as aluminum. The restraint body 244 may be hollow. The upper surface of the restraint body 244 may be coplanar with the upper surface of the battery cell housing 114, or it may be formed at a position higher than the upper surface of the battery cell housing 114, or it may be formed at a position lower than the upper surface of the battery cell housing 114. A spacer (not shown) may also be provided between the battery cell 100 disposed at the end in the first direction DR1 and the restraint body 244.

[0042] A pair of restraint portions 240 are configured to reduce the restraint force on the plurality of battery cells 100 when the temperature of the base 242 is above a reference value. In this embodiment, the base 242 is made of a material that softens when the temperature of the base 242 is above the reference value. For example, the base 242 is made of a synthetic resin with a softening point below the reference value.

[0043] like Figure 3 As shown, the energy storage device 10 may include a surrounding member 290. The surrounding member 290 is disposed 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 disposed between the bottom surface of the cell housing 114 and the retaining piece 284. The lower surface of the surrounding member 290 is in contact with the retaining piece 284 located on the upper surface of the bottom wall 212. The upper surface of the surrounding member 290 may also be in contact with the bottom surface of the cell housing 114. The surrounding member 290 is made of resin, metal, or the like. Furthermore, the surrounding member 290 may also be in contact with the lower surface of the cooling plate 150.

[0044] Equipment category 300 is housed within frame 200. For example... Figure 2 As shown, device type 300 is disposed in the space between partition wall 216 and peripheral wall 214 on the other side (rear side) of the lower housing 210 formed in the first direction DR1. Device type 300 may include junction boxes. Device type 300 may include relays, control devices, etc.

[0045] Equipment cooler 350 cools equipment 300. For example... Figure 2 and Figure 3 As shown, the equipment cooler 350 is disposed between the bottom wall 212 and the equipment 300. A thermally conductive adhesive 900 may be disposed between the equipment cooler 350 and the bottom wall 212.

[0046] Refrigerant piping 400 is housed within the frame 200. Refrigerant piping 400 is connected to each cooling plate 150 and the equipment cooler 350. For example... Figure 1 and Figure 2 As shown, an inflow port 181 and an outflow port 182 are provided on the front wall 214a of the peripheral wall 214. The refrigerant piping 400 is connected to the inflow port 181 and the outflow port 182. Therefore, the refrigerant (water, oil, etc.) supplied from the inflow port 181 flows into each cooling plate 150 and the equipment cooler 350 through the refrigerant piping 400, and after cooling each battery cell 100 and the equipment 300, it flows out from the outflow port 182 through the refrigerant piping 400.

[0047] like Figure 2 As shown, the refrigerant piping 400 has an upstream piping 410 and a downstream piping 420.

[0048] The upstream end of the upstream piping 410 is connected to the inflow port 181. The downstream end of the upstream piping 410 is connected to one end of the equipment cooler 350 on the second direction DR2. The upstream piping 410 is wired in a manner that passes between the front wall 214a and the constraint portion 240 formed on one side of the first direction DR1, and between the battery stack 11 disposed on one side of the second direction DR2 and the side wall 214b. The upstream piping 410 is connected to one end of each cooling plate 150 on the second direction DR2.

[0049] The upstream end of the downstream piping 420 is connected to the other end of the equipment cooler 350 on the second direction DR2. The downstream end of the downstream piping 420 is connected to the outlet port 182. The downstream piping 420 is wired in such a manner that it passes between the front wall 214a and the constraint portion 240 formed on one side of the first direction DR1, and between the energy storage stack 16 disposed on the other side of the second direction DR2 and the side wall 214b. The downstream piping 420 is connected to the other end of each cooling plate 150 on the second direction DR2.

[0050] In the energy storage device 10 described above, if a short circuit or other event causes discharge from the safety valve SV downwards in any of the energy storage cells 100, the discharge collides with the retaining plate 284 and the heat insulation component 282. Consequently, the retaining plate 284 melts and the heat insulation component 282 cracks, and the discharge containing the contents of the energy storage cell 100 (so-called fragments) flows into the exhaust path S through the through hole h1. Subsequently, the gas contained in the discharge expands in the exhaust path S, such as... Figure 3 As shown, the contents of the battery cell 100 are discharged from the housing 200 through the explosion-proof valve EV. Therefore, it is possible to prevent the contents of the battery cell 100 from adhering to the external terminals 116, etc.

[0051] At this time, the base 242 is heated by contact with the gas. As a result, since the temperature of the base 242 is above a reference value, the constraint force of the pair of constraint portions 240 on the plurality of battery cells 100 is reduced. Therefore, heat transfer from the heated battery cell 100 to the battery cell 100 adjacent to it can be suppressed.

[0052] After that, as Figure 3 As shown, gas is discharged from the housing 200 through the explosion-proof valve EV. Therefore, it is possible to prevent contents of the battery cell 100 from adhering to the external terminals 116, etc.

[0053] Hereinafter, variations of the above-described embodiments will be described.

[0054] It can also be like Figure 4 As shown, the energy storage device 10 also includes a restraint strap 250. In this example, each restraint portion 240 is constituted by a restraint plate (hereinafter referred to as "restraint plate 240") made of metal. The base 242 of the restraint plate 240 is located in the exhaust passage S.

[0055] A constraint band 250 connects a pair of constraint plates 240 to each other. The constraint band 250 is made of metal. The constraint band 250 is in thermal contact with each of the constraint plates 240. The constraint band 250 expands to reduce the constraint force when its temperature is above a reference value. Figure 4 In the example shown, the constraint band 250 is positioned above each of the battery packs 11-16. Figure 4 As shown, the restraint belt 250 has a belt body 252 and a fixing part 254.

[0056] The strip body 252 is formed in a flat plate shape. The strip body 252 is disposed between a pair of external terminals 116 on the upper surface of each cell housing 114. The strip body 252 may also be bonded to the upper surface of the cell housing 114. Preferably, the thickness (vertical dimension) of the strip body 252 is the same as or smaller than the sum of the thickness of each external terminal 116 and the thickness of the busbar (not shown) connected to the external terminal 116. The strip body 252 extends from one of a pair of constraint plates 240 to the other. From the viewpoint of improving the bending stiffness of the strip body 252, a reinforcing rib (not shown) extending along a first direction DR1 may be formed in the strip body 252. Alternatively, a protrusion (not shown) extending along the first direction DR1 may be formed on at least one of the upper and lower surfaces of the strip body 252.

[0057] The fixing part 254 is connected to the end of the main body 252 on the first direction DR1. For example... Figure 4 As shown, the fixing part 254 is fixed to the outer side of each constraint plate 240 in the first direction DR1 by fastening members (not shown) and the like.

[0058] The energy storage device 10 may also include a clamping member 370. The clamping member 370 is clamped between the main body 252 and the upper cover 220. Multiple clamping members 370 may be arranged at intervals in the first direction DR1. Alternatively, a single clamping member 370 may be arranged between the main body 252 and the upper cover 220. The clamping member 370 is made of resin, metal, or the like.

[0059] In this method, if gas flows into the exhaust path S, the heat of the gas is transferred from the base 242 to the constraint band 250 via the constraint plate 240. Moreover, since the constraint band 250 expands when its temperature exceeds a reference value, the constraint force of the pair of constraint plates 240 is reduced.

[0060] Furthermore, in this method, when the internal pressure of the cell housing 114 rises due to a short circuit or other reasons, the main body 252 is adhered to the upper surface of the cell housing 114, thus preventing the upper surface of the cell housing 114 from cracking when the internal pressure rises. As a result, the discharge from the battery cell 100 is effectively discharged downwards from the safety valve SV provided on the lower surface of the cell housing 114.

[0061] Those skilled in the art will understand that the exemplary embodiments described above are specific examples of the following approaches.

[0062] Method 1

[0063] An energy storage device includes: a plurality of energy storage cells arranged in one direction; a bottom wall disposed below the plurality of energy storage cells; a panel component disposed below the bottom wall and defining a smoke exhaust path together with the bottom wall; and a pair of restraining portions restraining the plurality of energy storage cells from both sides of the plurality of energy storage cells in the one direction, wherein a safety valve is provided on the lower surface of each plurality of energy storage cells, the bottom wall having: a plurality of through holes disposed opposite to each of the safety valves; and an insertion hole for insertion of at least one of the pair of restraining portions, wherein at least one of the pair of restraining portions includes a base disposed in the smoke exhaust path, and the pair of restraining portions are configured to reduce the restraining force on the plurality of energy storage cells when the temperature of the base is above a reference value.

[0064] In this energy storage device, when gas discharged from the safety valve of the battery cell and flows into the exhaust path through the through-hole, the base is heated by contact with the gas as it expands in the exhaust path. As a result, since the temperature of the base exceeds a reference value, the constraint force of the pair of restraints on the multiple battery cells is reduced. Therefore, heat transfer from the heated battery cell to adjacent battery cells can be suppressed.

[0065] Method 2

[0066] According to the energy storage device of method 1, one of the pair of constraint portions further has a constraint portion body extending upward from the base, the constraint portion body and the other of the pair of constraint portions together exert the constraint force on the plurality of energy storage cells, and the base is made of a material that softens when the temperature of the base is above the reference value.

[0067] In this method, the base softens when the temperature of the base reaches a reference value or higher due to contact between the gas flowing into the exhaust path and the base, thus reducing the restraining force of the main body of the restraint section.

[0068] Method 3

[0069] According to the energy storage device of embodiment 1, the energy storage device further comprises a constraint band that is in thermal contact with the pair of constraint portions and connects the pair of constraint portions to each other, at least one of the pair of constraint portions comprises a constraint plate including the base portion, and the constraint band expands in a manner that reduces the constraint force when the temperature of the constraint band is above the reference value.

[0070] In this method, if gas flows into the exhaust path, the gas transfers heat from the base through the constraint plate to the constraint belt, thereby causing the constraint belt to expand and the constraint force to decrease.

[0071] Method 4

[0072] According to the energy storage device of embodiment 3, the energy storage device further comprises: a top cover disposed above the plurality of energy storage cells; and a clamping member clamped between the constraint strap and the top cover.

[0073] In this method, the upper surface of the battery cell can be suppressed from cracking when the internal pressure of the battery cell rises because the clamping component and the top cover press the constraint band from above.

[0074] It should be noted that the embodiments disclosed herein are illustrative in all respects and not restrictive. The scope of this disclosure is defined not by the description of the embodiments above but by the technical solutions, and includes all modifications within the meaning and scope equivalent to the technical solutions.

Claims

1. An energy storage device, wherein, have: Multiple battery cells are arranged in one direction; The bottom wall is located below the plurality of battery cells; A panel component is disposed below the bottom wall and, together with the bottom wall, defines the smoke exhaust path; as well as A pair of constraint portions constrain the plurality of battery cells from both sides in the said one direction. A safety valve is provided on the lower surface of each of the plurality of battery cells. The bottom wall has: Multiple through holes are respectively located opposite each of the aforementioned safety valves; and A through-hole is provided for insertion of at least one of the pair of constraint parts. At least one of the pair of constraint portions includes a base disposed in the smoke exhaust path. The pair of constraint portions are configured to reduce the constraint force on the plurality of battery cells when the temperature of the base is above a reference value.

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

3. The energy storage device according to claim 1, wherein, It also includes a constraint band that makes thermal contact with the pair of constraint parts and connects the pair of constraint parts to each other. At least one of the pair of constraint portions has a constraint plate including the base portion. The constraint band expands in a manner that reduces the constraint force when the temperature of the constraint band reaches a value above the reference value.

4. The energy storage device according to claim 3, wherein, It also has: The top cover is disposed above the plurality of battery cells; and A clamping component is clamped between the constraint strap and the upper cover.

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