Electricity storage device

Abstract

A power storage device is provided with a plurality of power storage cells, a bottom wall, and a panel member that defines a smoke discharge path together with the bottom wall. Each of the power storage cells includes a cell case that accommodates an electrode body. And a safety valve is arranged on the lower surface of the single shell. The bottom wall has a through hole provided at a position facing the relief valve. The safety valve is provided with a cracking part which cracks when the internal pressure of the single shell reaches a reference value; and a connecting portion that connects the single case and the cleavage portion. When the internal pressure of the single case reaches a reference value, the connecting portion is deformable into a shape bulging toward the outside of the single case.

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 comprising multiple cells, a housing containing the cells, a protective member protecting the bottom portion of the housing, and a cover. The protective member is fixed to the bottom portion of the housing by fasteners. A pressure relief mechanism is provided on the bottom surface of each cell. Exhaust streams discharged from the pressure relief mechanism flow into a collection cavity formed between the bottom portion of the housing and the protective member. Summary of the Invention

[0003] In the battery described in Japanese Patent Application Publication No. 2023-126584, the discharge from the pressure relief mechanism of one cell may adhere to other cells.

[0004] The purpose of this disclosure is to provide an energy storage device capable of preventing discharge from one energy storage cell from adhering to other energy storage cells.

[0005] One aspect of the energy storage device disclosed herein includes: a plurality of energy storage cells; a bottom wall disposed below the plurality of energy storage cells; and a panel member disposed below the bottom wall, defining a smoke exhaust path together with the bottom wall. Each of the plurality of energy storage cells includes a cell housing housing an electrode body. A safety valve is disposed on the lower surface of the cell housing. The bottom wall has a through hole disposed opposite to the safety valve. The safety valve has a cracking portion that cracks when the internal pressure of the cell housing reaches a reference value, and a connecting portion that connects the cell housing to the cracking portion. The connecting portion can be deformed into a shape that bulges outward toward the outside of the cell housing when the internal pressure of the cell housing reaches the reference value.

[0006] According to this disclosure, it is possible to provide an energy storage device that can suppress the adhesion of discharges from one energy storage cell to other energy storage cells. Attached Figure Description

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

[0008] Figure 1 This is a schematic diagram of a vehicle equipped with an energy storage device according to one embodiment of the present disclosure.

[0009] Figure 2 It is a three-dimensional diagram that roughly represents an energy storage device.

[0010] Figure 3 It is a plan view that roughly shows the state of the energy storage device with the top cover removed.

[0011] Figure 4 yes Figure 3 A cross-sectional view at line IV-IV.

[0012] Figure 5 This is a diagram that roughly represents a safety valve.

[0013] Figure 6 yes Figure 5 A sectional view at line VI-VI.

[0014] Figure 7 It is a cross-sectional view that roughly shows the state of the cracked part. Detailed Implementation

[0015] Embodiments of this disclosure will be described with reference to the accompanying drawings. Furthermore, in the drawings referred to below, the same or equivalent parts are labeled with the same reference numerals.

[0016] Figure 1 This is a diagram that schematically illustrates a vehicle equipped with an energy storage device according to one embodiment of the present disclosure. Figure 2 It is a three-dimensional diagram that roughly represents an energy storage device. Figure 3 It is a plan view that roughly shows the state of the energy storage device with the top cover removed. Figure 4 yes Figure 3 A cross-sectional view at line IV-IV.

[0017] like Figure 1 As shown, vehicle 1 includes a vehicle body 2 and an electric storage device 10. Examples of vehicles 1 include hybrid electric vehicles, plug-in hybrid electric vehicles, and battery electric vehicles.

[0018] like Figure 1 and Figure 2 As shown, the vehicle body 2 includes a frame member 20. The frame member 20 is disposed at the bottom of the vehicle body 2. The frame member 20 is formed in a generally square cylindrical shape that surrounds the energy storage device 10.

[0019] The energy storage device 10 is installed on the frame member 20. For example... Figures 1-4 As shown, the energy storage device 10 includes six energy storage stacks 11 to 16, a frame 200, equipment 300, an equipment cooler 350, and refrigerant piping 400. Furthermore, the number of energy storage stacks is not limited to six.

[0020] Each of the energy storage stacks 11 to 16 is formed into a rectangular parallelepiped shape that is longer in the first direction. For example... Figure 3As shown, six battery stacks 11-16 are arranged along a second direction orthogonal to both the first and vertical directions. In this embodiment, the first direction corresponds to the front-to-back direction of the vehicle, and the second direction corresponds to the left-to-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.

[0021] Multiple energy storage cells 100 are arranged in a manner that follows a first direction. For example... Figure 4 As shown, each battery cell 100 has an electrode body 112, a cell housing 114, and a pair of external terminals 116.

[0022] The electrode body 112 can be composed of a wound body formed by winding positive and negative electrode sheets through a separator, or it can be composed of a laminated body formed by stacking positive and negative electrode sheets through a separator. The electrode body 112 is formed into a shape that is long in the second direction.

[0023] The housing 114 houses the electrode 112. The housing 114 is formed in a cuboid shape. The housing 114 is made of a metal such as aluminum. A safety valve 115 is provided on the lower surface of the housing 114. Details of the safety valve 115 will be described later.

[0024] A pair of external terminals 116 are disposed on the upper surface of the single housing 114. The pair of external terminals 116 are positioned separately from each other in the width direction of the single housing 114. In addition, the width direction of the single housing 114 corresponds to a second direction.

[0025] like Figure 4 As shown, each cooling plate 150 is disposed between a pair of adjacent energy storage cells 100 in the first direction. Each cooling plate 150 is formed as a flat plate that is elongated in the second direction. Each cooling plate 150 has a flow path (not shown) for refrigerant to flow along the second direction.

[0026] The housing 200 contains six battery packs 11-16. (Example) Figures 2 to 4 As shown, the frame 200 includes a lower shell 210, an upper cover 220, and a panel component 230.

[0027] 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, a peripheral wall 214, and a pair of partition walls 216.

[0028] The bottom wall 212 is located below each of the battery stacks 11-16. 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 flat plate. Figure 4As shown, multiple through holes 212h are formed in the bottom wall 212. Each through hole 212h is located opposite to the safety valve 115.

[0029] Multiple heat-insulating components (not shown) may also be provided on the bottom wall 212. Each heat-insulating component has a shape that covers the through hole 212h. Each heat-insulating component has the function of protecting each battery cell 100 from the gas discharged from the safety valve 115. Each heat-insulating component is, for example, made of mica, which is formed by solidifying natural inorganic minerals through hot pressing.

[0030] 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 also be hollow. The peripheral wall 214 has a front wall 214a and a pair of side walls 214b.

[0031] The front wall 214a is formed on one side of each of the energy storage stacks 11 to 16 in the first direction. Figure 3 (Left side of the vehicle). The front wall 214a extends in the second direction. Furthermore, in this embodiment, one side in the first direction corresponds to the front side in the longitudinal direction of the vehicle.

[0032] A pair of sidewalls 214b are spaced apart from each other in a second direction. Each sidewall 214b extends in a first direction. One end (front end) of each sidewall 214b in the first direction is connected to the front wall 214a.

[0033] A pair of partition walls 216 divides the space surrounded by the bottom wall 212 and the peripheral wall 214 into a space where each of the battery stacks 11-16 is arranged and other spaces. The pair of partition walls 216 are arranged separately from each other in a first direction. Each partition wall 216 extends in a second direction. Each partition wall 216 may also be hollow. The pair of partition walls 216 have the function of constraining each of the battery stacks 11-16 from both sides in the first direction. Figure 3 As shown, the end of the partition wall 216 formed on one side (front side) in the first direction is separated from each side wall 214b in the second direction. The end of the partition wall 216 formed on the other side (rear side) in the first direction is connected to each side wall 214b in the second direction.

[0034] The upper cover 220 is positioned above each of the battery stacks 11 to 16. The upper cover 220 and the lower housing 210 together house the six battery stacks 11 to 16. Specifically, the upper cover 220 and the lower housing 210 together 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 member or bolts.

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

[0036] like Figure 4 As shown, 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 exhausting the gas discharged from the safety valve 115 of the battery cell 100 to the outside of the frame 200.

[0037] like Figure 3 and Figure 4 As shown, a smoke exhaust duct section 218 is formed on 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 290 is provided at the downstream end of the smoke exhaust duct section 218. The explosion-proof valve 290 releases the pressure inside the frame 200. The explosion-proof valve 290 opens when the pressure inside the frame 200 reaches or exceeds a reference value. The explosion-proof valve 290 is composed of a check valve. Figure 4 As shown, when gas is discharged from any of the battery cells 100, the gas diffuses in the first direction through the exhaust path S and is discharged outside the frame 200 through the exhaust pipe section 218 and the explosion-proof valve 290.

[0038] Device class 300 is housed within enclosure 200. For example... Figure 3 As shown, device class 300 is disposed in the space formed between partition wall 216 and peripheral wall 214, wherein partition wall 216 is formed on the other side (rear side) of lower housing 210 in the first direction. Device class 300 may include junction box. Device class 300 may include relays or control devices, etc.

[0039] Equipment cooler 350 cools equipment 300. For example... Figure 3 and Figure 4 As shown, the equipment cooler 350 is disposed between the bottom wall 212 and the equipment 300. A thermally conductive adhesive 900 may also be disposed between the equipment cooler 350 and the bottom wall 212.

[0040] 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 2 and Figure 3As 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.

[0041] like Figure 3 As shown, the refrigerant piping 400 has an upstream piping 410 and a downstream piping 420.

[0042] 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 in the second direction. The upstream piping 410 is configured to connect between the front wall 214a and the partition wall 216 formed on one side in the first direction, and between the battery stack 11 and the side wall 214b arranged on one side in the second direction. The upstream piping 410 is connected to one end of each cooling plate 150 in the second direction.

[0043] The upstream end of the downstream piping 420 is connected to the other end of the equipment cooler 350 in the second direction. The downstream end of the downstream piping 420 is connected to the outlet port 182. The downstream piping 420 is configured to pass between the front wall 214a and the partition wall 216 formed on one side in the first direction, and between the battery stack 16 and the side wall 214b arranged on the other side in the second direction. The downstream piping 420 is connected to the other end of each cooling plate 150 in the second direction.

[0044] Next, refer to Figures 5-7 The safety valve 115 will be described in detail below. The safety valve 115 has a split portion 115a and a connecting portion 115b.

[0045] The crack 115a cracks when the internal pressure of the monolithic shell 114 reaches a reference value. The crack 115a can also be formed as a circle when viewed from below. A crack guide (thin-walled portion) is formed in the crack 115a.

[0046] The connecting portion 115b connects the single-piece shell 114 and the cracked portion 115a. The connecting portion 115b surrounds the cracked portion 115a in an annular shape. The thickness of the cracked portion 115a gradually decreases from the connecting portion 115b toward the center of the cracked portion 115a.

[0047] like Figure 6 As shown, the connecting portion 115b has a shape that is recessed towards the inside of the single-unit housing 114 when the internal pressure of the single-unit housing 114 is less than a reference value. Figure 7As shown, the connecting portion 115b can deform into a shape that bulges outward toward the outside (lower side in this embodiment) of the single-unit housing 114 when the internal pressure of the single-unit housing 114 reaches a reference value. The distance H between the lower surface of the single-unit housing 114 and the upper surface of the bottom wall 212 is set to the following length: when the cracked portion 115a has cracked, the lower end of the cracked portion 115a is located within the through hole 212h.

[0048] In the energy storage device 10 described above, when the internal pressure of the cell housing 114 in any one of the energy storage cells 100 reaches the reference value due to a short circuit, the distance between the cracked portion 115a of the safety valve 115 and the bottom wall 212 decreases because the connecting portion 115b bulges towards the bottom wall 212. Furthermore, as... Figure 7 As shown, when the cracked portion 115a is cracked, its lower end is located within the through hole 212h. Therefore, when the discharge from the battery cell 100 is discharged from the cracked portion 115a, the discharge effectively flows into the exhaust path S. Thus, the discharge is prevented from scattering towards the battery cell 100 or adhering to other battery cells.

[0049] Then, the gas contained in the exhaust flowing from safety valve 115 into exhaust path S diffuses within exhaust path S, such as... Figure 4 As shown, the contents of the battery cell 100 are discharged through the explosion-proof valve 290 from the housing 200. Therefore, the contents of the battery cell 100 contained in the discharge (so-called fragments) are suppressed from adhering to the external terminals 116 of the battery cell 100, etc.

[0050] In addition, the distance H between the lower surface of the single shell 114 and the upper surface of the bottom wall 212 can also be set to the following length: when the cracked part 115a has cracked, the lower end of the cracked part 115a is located above the through hole 212h.

[0051] Those skilled in the art will understand that the above exemplary embodiments are specific examples of the following approaches.

[0052] Method 1

[0053] An energy storage device, comprising:

[0054] Multiple battery cells;

[0055] The bottom wall is disposed below the plurality of battery cells; and

[0056] The panel component is disposed below the bottom wall and, together with the bottom wall, defines the smoke exhaust path.

[0057] Each of the plurality of battery cells includes a cell housing that contains the electrode body.

[0058] A safety valve is provided on the lower surface of the single-unit housing.

[0059] The bottom wall has a through hole located opposite the safety valve.

[0060] The safety valve has the following features:

[0061] The crack occurs when the internal pressure of the monolithic shell reaches a reference value; and

[0062] The connecting part connects the single-piece shell and the cracked part.

[0063] The connecting part can deform into a shape that bulges outward toward the outside of the single-unit shell when the internal pressure of the single-unit shell reaches the reference value.

[0064] In this energy storage device, within a single cell, when the internal pressure of the cell casing reaches a reference value, the connecting portion bulges towards the bottom wall, thus reducing the distance between the safety valve's opening and the bottom wall. Consequently, when the discharge from the energy storage cell exits through the opening, the discharge effectively flows into the exhaust path. This prevents the discharge from one energy storage cell from scattering towards or adhering to other energy storage cells.

[0065] Method 2

[0066] According to the energy storage device of method 1, the connecting portion has a shape that is recessed toward the inside of the single-unit housing when the internal pressure of the single-unit housing is less than the reference value.

[0067] Method 3

[0068] According to the energy storage device of method 1 or 2, the thickness of the cracked portion gradually decreases from the connecting portion toward the center of the cracked portion.

[0069] In this method, the cracked portion is effectively cracked.

[0070] Method 4

[0071] According to any one of the embodiments 1 to 3, the distance between the lower surface of the single-unit housing and the upper surface of the bottom wall is set to the following length: when the cracked part is cracked, the lower end of the cracked part is located in the through hole.

[0072] In this method, when the discharge from the battery cell is discharged from the crack, the discharge flows more reliably into the exhaust path.

[0073] Furthermore, the embodiments disclosed herein are illustrative in all respects and should not be considered limiting. The scope of this disclosure is set forth in the claims, not in the description of the above embodiments, and includes all modifications within the meaning and scope equivalent to the claims.

Claims

1. An energy storage device, wherein, have: Multiple battery cells; The bottom wall is disposed below the plurality of battery cells; and The panel component is disposed below the bottom wall and, together with the bottom wall, defines the smoke exhaust path. Each of the plurality of battery cells includes a cell housing that contains the electrode body. A safety valve is provided on the lower surface of the single-unit housing. The bottom wall has a through hole, which is located opposite the safety valve. The safety valve has the following features: The crack occurs when the internal pressure of the single-unit shell reaches a reference value; as well as The connecting part connects the single-piece shell and the cracked part. The connecting part can deform into a shape that bulges outward toward the outside of the single-unit shell when the internal pressure of the single-unit shell reaches the reference value.

2. The energy storage device according to claim 1, wherein, The connecting portion has a shape that is recessed toward the inside of the single-unit housing when the internal pressure of the single-unit housing is less than the reference value.

3. The energy storage device according to claim 1, wherein, The thickness of the cracked portion gradually decreases from the connecting portion toward the center of the cracked portion.

4. The energy storage device according to claim 1, wherein, The distance between the lower surface of the single-unit shell and the upper surface of the bottom wall is set to the following length: when the cracked part has cracked, the lower end of the cracked part is located in the through hole.

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