JP2019061736A - Power storage device - Google Patents

Abstract

To provide a good power storage device capable of preventing concatenation of overheat state between power storage elements well.SOLUTION: A power storage device 100 includes multiple power storage elements 1, and a cooling part 30 for cooling the power storage elements 1. The cooling part 30 incorporates liquid, and has a heat transmission part 31 placed at least between the power storage elements 1, in contact therewith, and cools the power storage elements 1 by the heat of vaporization of the liquid. In the heat transmission part 31 in contact with the power storage element 1 that generated heat, the power storage element 1 is cooled well by the heat of vaporization when the incorporated liquid evaporates.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a power storage device provided with a plurality of power storage elements.

  A chargeable / dischargeable storage element is used in various devices such as mobile phones and automobiles. Above all, vehicles powered by electrical energy such as electric vehicles (EVs) and plug-in hybrid electric vehicles (PHEVs) require large amounts of energy, so they are equipped with a large-capacity storage device equipped with a plurality of storage elements. There is.

  In such a storage device, when the temperature of any one storage element is excessively increased due to some cause, which is not a normal use state, the heat of the storage element is conducted to the adjacent storage element to cause adjacent storage. The element is heated. Thereby, when the active material of the electrode of the adjacent storage element is heated to the self-heating temperature or more, the adjacent storage element is also heated by the self-heating and further heats the storage element next to the storage element. A large number of storage elements may overheat.

  When using a storage element in which a metal case is covered with a resin film, when the storage element is overheated, the resin film is melted and the metal cases are in contact with each other to promote heat conduction, resulting in an overheat state. Chains are likely to occur. In particular, when a metal case is used as an electrode, or when the metal case has an abnormal potential due to some abnormality, an abnormal current is applied to an adjacent storage element by being in electrical contact with the case of the adjacent storage element. It may cause an overheat condition.

  JP-A-2015-195149 discloses a technique for suppressing conduction of heat of a storage element to an adjacent storage element.

JP, 2015-195149, A

In the power storage device of Patent Document 1, the conduction of heat between the power storage elements is suppressed by the partition member formed of the mica accumulation material.
In recent years, it has been required to further increase the capacity of the storage element and the storage device. When the capacity of the storage element is increased, the energy and heat released from the storage element when the storage element is overheated are also very large. The heat insulation can be enhanced by increasing the thickness of the air layer or the partition member between the storage elements, but with such a method, the energy density of the storage device decreases. Therefore, there is a need for new measures that can prevent the chain of overheated states between storage elements without reducing the energy density.

  An object of the present invention is to provide a power storage device capable of favorably preventing a chain of overheating between storage elements.

  A storage device according to the present invention includes a plurality of storage devices and a cooling unit for cooling the storage devices, the cooling unit containing a liquid, disposed at least between the storage devices, and in contact with the storage devices. And a heat transfer portion for cooling the storage element by the heat of vaporization of the liquid.

According to the present invention, in the heat transfer section in contact with the heated storage element, the liquid contained therein absorbs heat from the storage element and evaporates, whereby the storage element is cooled well. Since the heat transfer portion is disposed at least between the storage elements, the conduction of heat to the storage element adjacent to the generated storage element is suppressed, and in the case of having three or more storage elements, it is chained to the adjacent storage elements. Heat transfer to the That is, the chain of the overheat state between the storage elements is well prevented.
In addition, since the liquid is contained in the heat transfer portion, it is vaporized and then liquefied in the heat transfer portion to be reused for cooling the storage element, whereby the storage element is efficiently cooled.

It is a perspective view of an electrical storage element. It is a perspective view of the electrical storage apparatus which concerns on 1st Embodiment. It is a perspective view of a cooling unit. It is the IV-IV sectional view taken on the line of FIG. It is an explanatory view for explaining cooling by a cooling unit when a storage element generates heat. It is a perspective view of a cooling unit concerning a 2nd embodiment. It is explanatory drawing in the case where internal space is connected in 2nd Embodiment. It is a perspective view of a cooling unit concerning a 3rd embodiment. It is a perspective view of the cooling unit concerning a 4th embodiment. It is an explanatory view explaining cooling when a rupture valve of a central storage element is opened.

Hereinafter, the present invention will be specifically described based on the drawings showing the embodiments thereof.
First Embodiment
FIG. 1 is a perspective view of the storage element 1 according to the first embodiment. Hereinafter, although the case where the storage element 1 is a lithium ion secondary battery will be described, the storage element 1 is not limited to a lithium ion secondary battery.
The storage element 1 includes a case 11 having a cover plate 2 and a case main body 3, a positive electrode terminal 4, a negative electrode terminal 8, gaskets 6 and 10, a rupture valve 20, a current collector and an electrode body (not shown).

  The case 11 is made of, for example, a metal such as aluminum, an aluminum alloy, stainless steel, or a synthetic resin, has a rectangular parallelepiped shape, and accommodates an electrode body and an electrolytic solution (not shown).

The positive electrode terminal 4 has a shaft portion penetrating the lid plate 2 and a plate portion provided at one end of the shaft portion.
The gasket 6 is made of, for example, a synthetic resin such as polyphenylene sulfide (PPS) or polypropylene (PP). The positive electrode terminal 4 is provided so as to pass through the lid plate 2 in a state in which the inner surface of the plate portion and the shaft portion are covered with the gasket 6 and insulated.

  The negative electrode terminal 8 has a shaft portion penetrating the cover plate 2 and a plate portion provided at one end of the shaft portion. The negative electrode terminal 8 is provided so as to penetrate the lid plate 2 in a state in which the inner surface of the plate portion and the shaft portion are covered by the gasket 10 and the state is insulated.

The electrode body is a laminated type having a main body in which a plurality of positive electrode plates and negative electrode plates are alternately stacked via a separator to form a rectangular parallelepiped shape, and a positive electrode tab and a negative electrode tab extending from the main body toward the lid plate 2 May be The positive electrode tab is connected to the positive electrode terminal 4 via a current collector. The negative electrode tab is connected to the negative electrode terminal 8 via a current collector.
The electrode body may be a wound type obtained by winding a positive electrode plate and a negative electrode plate in a flat shape via a separator.
The electrode body is more preferably a laminate type in which there is little swelling due to charge and discharge (expansion of an outer body such as a metal case like case 11 and a pouch case of laminate structure). Since there is little swelling of the exterior body, it can be suppressed that the exterior body presses the heat transfer portion 31 during normal use.

The positive electrode plate is obtained by forming a positive electrode active material layer on a positive electrode substrate foil that is a plate-like (sheet-like) or long strip-like metal foil made of aluminum, an aluminum alloy or the like. The negative electrode plate is obtained by forming a negative electrode active material layer on a negative electrode substrate foil that is a plate-like (sheet-like) or long strip-like metal foil made of copper and copper alloy or the like. The separator is a microporous sheet made of a synthetic resin.
As the positive electrode active material used in the positive electrode active material layer or the negative electrode active material used in the negative electrode active material layer, known materials can be used appropriately as long as the positive electrode active material or the negative electrode active material can occlude and release lithium ions. .

Examples of positive electrode active materials include polyanion compounds such as LiMPO ₄ , LiM ₂ SiO ₄ , LiMBO ₃ (M is one or more transition metal elements selected from Fe, Ni, Mn, Co, etc.), titanium Using lithium spinel compounds such as lithium oxalate and lithium manganate; and lithium transition metal oxides such as LiMO 2 (M is one or more transition metal elements selected from Fe, Ni, Mn, Co, etc.) it can.

As the negative electrode active material, for example, lithium metal, lithium alloy (lithium-aluminum, lithium-silicon, lithium-lead, lithium-tin, lithium-aluminum-tin, lithium-gallium such as wood alloy, etc.) Other than these, alloys capable of storing and releasing lithium, carbon materials (eg, graphite, non-graphitizable carbon, graphitizable carbon, low-temperature fired carbon, amorphous carbon, etc.), metal oxides, lithium metal oxides (Li ₄₎ Ti ₅ O ₁₂ etc.), polyphosphoric acid compounds etc. may be mentioned.

  The rupture valve 20 has a rupture 200 formed by partially reducing the plate thickness. When the internal pressure of the storage element 1 rises, it breaks along the fractured portion 200 to form a tongue-like portion, and the portion jumps outward to form an opening in the lid plate 2.

FIG. 2 is a perspective view of power storage device 100 according to the present embodiment, and FIG. 3 is a perspective view of cooling unit 30.
Power storage device 100 includes a plurality of power storage elements 1, a cooling unit 30 for cooling power storage elements 1, and a case 40 for storing power storage elements 1 and cooling section 30. Although three storage elements 1 are accommodated in FIG. 2, the number of storage elements 1 is not limited to three.
The case 40 has a box shape and is made of, for example, an insulating material such as a synthetic resin. Case 40 arrange | positions the electrical storage element 1 and the cooling unit 30 in a predetermined position, and protects them from a shock. The case 40 is provided with an external electrode terminal (not shown) for charging electricity from the outside and discharging the electricity to the outside.

The cooling unit 30 may be made of a metal such as aluminum having good thermal conductivity and heat resistance, or may be subjected to an insulation process by forming an insulating film on the surface.
As shown in FIG. 3, the cooling unit 30 includes a plate-like heat transfer unit 31, connection units 32 and 33 connecting the heat transfer unit 31, and an internal pressure release valve 34. The two heat transfer parts 31 are interposed between the long side surfaces of the adjacent storage element 1, and the two heat transfer parts 31 abut on the long side surfaces of the storage element 1 at both ends. Here, the long side surface is provided to extend upward from the long side of the bottom surface of the storage element 1 in FIG. 1, and means the side surface having the largest area among the side surfaces. An internal pressure release valve 34 is provided on the upper surface of one of the outer heat transfer portions 31. The number of heat transfer units 31 may be provided corresponding to the number of storage elements 1. The heat transfer portion 31 is provided between the storage elements 1 and is provided so as to abut on the long side surfaces of the storage elements 1 at both ends.
The outer heat transfer section 31 can be omitted. For example, when the number of storage elements 1 is five, four heat transfer parts 31 are disposed between the storage elements 1, and the four heat transfer parts 31 are connected by the connection parts 32 and 33. The long side of the outer storage element 1 is brought into contact with the side of the case 40. The cooling efficiency is better if the outer heat transfer section 31 is provided.

FIG. 4 is a cross-sectional view taken along line IV-IV of FIG.
The internal pressure release valve 34 is a circular groove, and as shown in FIG. 4, the thickness of the bottom of the groove is thinner than the thickness of the other part. The internal pressure release valve 34 is formed by cutting, pressing or the like. When the internal pressure release valve 34 is formed by cutting, a device capable of cutting a curved surface such as a three-dimensional NC is used. When the internal pressure release valve 34 is formed by pressing, it is formed so as to press an imprint by a mold having a protrusion.

The heat transfer portion 31 is hollow, and the liquid is contained in the internal space. The liquid is preferably nonflammable, has a large heat of vaporization, is corrosion resistant, and does not generate toxic gas. Preferably the liquid comprises water. Water is harmless, less corrosive, not pyrophoric, and highly safe. The liquid may be fluid or gel-like, and may include a refrigerant such as a solution of an HFC refrigerant and an inert gas. The boiling point may be adjusted by mixing water and components other than water.
The heat transfer portion 31 is not damaged based on the internal volume of the heat transfer portion 31 and the connection portions 32 and 33, the assumed heat generation temperature of the storage element 1, the volume when the liquid is vaporized, and the like. To set.

An upper portion of one end of the long side surface of the adjacent heat transfer portion 31 is connected by the connection portion 32. The connecting portion 32 is hollow so that the gas in the heat transfer portion 31 to be connected flows through the connecting portion 32.
The lower portion of one end of the long side surface of the adjacent heat transfer portion 31 is connected by the connection portion 33. The connecting portion 33 is hollow, and the liquid in the heat transfer portion 31 to be connected flows through the connecting portion 33.
That is, the heat transfer part 31, the connection part 32, and the connection part 33 which adjoin are connecting internal space.

FIG. 5 is an explanatory diagram for illustrating cooling by the cooling unit 30 when the storage element 1 generates heat.
It is assumed that the cooling unit 30 contains water W as a liquid, and the storage element 1 at the center generates heat.
Heat is conducted from the storage element 1 generating heat to the heat transfer sections 31, 31 on both sides, and the water W in the heat transfer section 31 evaporates (FIG. 5A). The heat of vaporization when the water W evaporates is large, and the storage element 1 is rapidly cooled by the endothermic reaction. The amount of water W in the heat transfer section 31 on both sides of the storage element 1 that has generated heat decreases due to evaporation.

  The water vapor in the heat transfer section 31 flows upward by thermal convection, and moves to the outer heat transfer section 31 having a low temperature through the connection sections 32 and 32 (FIG. 5B). The steam condenses in the outer heat transfer section 31, and the amount of water W in the outer heat transfer section 31 increases.

  The water W flows to the inner heat transfer part 31 via the connection part 33 by the amount increased in the outer heat transfer part 31, and the water amounts of the four heat transfer parts 31 become equal (FIG. 5C). The circulated water W also absorbs the heat of the storage element 1, evaporates, and circulates in the same manner as described above.

  When water is used as the liquid, the water evaporates at 100 ° C., and the heat of vaporization is large. Therefore, the heat of the storage element 1 can be suppressed lower than one hundred tens of degrees that may cause a failure event. That is, the storage device 100 can cool the storage element 1 rapidly with high safety.

  The above power storage device 100 includes a plurality of power storage elements 1 and a cooling unit 30 for cooling the power storage elements 1, the cooling section 30 containing a liquid, disposed at least between the power storage elements 1, and A heat transfer portion 31 is provided in contact with the long side surface of the storage element 1 to cool the storage element 1 by the heat of vaporization of the liquid.

According to the above configuration, in the heat transfer section 31 in contact with the storage element 1 in which heat is generated, the storage heat is taken off when the liquid contained is vaporized, so that the storage element 1 is cooled well. Since the heat transfer portion 31 is disposed at least between the storage elements 1, the conduction of heat to the storage element 1 adjacent to the generated storage element 1 is suppressed, and the heat is further transferred to the adjacent storage elements 1 in a chained manner. Is suppressed. That is, the chain of the overheat state between the storage elements 1 is well prevented.
The structure for cooling the storage element 1 is simple, and the storage element 1 can be cooled even when heat generation to a low degree occurs.
Further, since the liquid is contained in the heat transfer section 31, it is vaporized and then liquefied in the heat transfer section 31 and reused for cooling the storage element 1, thereby efficiently cooling the storage element 1.

  In the power storage device 100 described above, the cooling unit 30 includes connecting portions 32 and 33 that connect the plurality of heat transfer units 31 so that the internal space is in communication.

According to the above configuration, the gas generated by the vaporization of the liquid flows through the insides of the connecting portions 32 and 33 by thermal convection in one heat transfer portion 31 in contact with the heated storage element 1, and the other heat transfer portion It flows to 31. The gas is liquefied in the other heat transfer section 31 and flows to the one heat transfer section 31 to circulate the liquid.
Therefore, the liquid is reused to cool the storage element 1 and the storage element 1 is efficiently cooled.
Further, the temperature difference between the long side in contact with one heat transfer portion 31 and the long side in contact with the other heat transfer portion 31 of one storage element 1 is reduced, and the temperature difference between storage elements 1 is reduced. Is reduced. And, by the circulation of the gas and the liquid, it is possible to reduce the temperature difference between the plurality of storage elements 1 and to cool efficiently. Even when heat generation is not abnormal and occurs to a low degree, the heat transfer unit 31 properly dissipates the heat from the storage element 1 and the temperature difference between the storage elements 1 is reduced.

  In the storage device 100 described above, the cooling unit 30 includes an internal pressure release valve 34 that releases the internal pressure when the internal pressure of the cooling unit 30 exceeds a predetermined pressure.

  According to the above configuration, when the evaporation amount of the liquid is large and the internal pressure of the cooling unit 30 exceeds the predetermined pressure, the internal pressure release valve 34 is opened, and the gas is discharged to the outside. It is prevented that the cooling unit 30 is expanded by the gas and the storage element 1 is pressed. If combustible gas is present, mixing with the gas prevents ignition.

Even when the storage element 1 at the end rather than the center generates heat, the heat transfer portion 31 absorbs heat as described above, and the storage element 1 is rapidly cooled. The long side of the storage element 1 adjacent to the storage element 1 that generates heat is also cooled rapidly, and the heat transfer from the storage element 1 that generates heat is suppressed, and the chain of superheat states between storage elements is prevented.
The structure of the cooling unit 30 is not limited to the structure shown in FIG. The connecting portion may be provided such that the rectangular tube passes through the upper portion and the lower portion of one end of each of the four heat transfer portions 31 in the longitudinal direction.

Second Embodiment
FIG. 6 is a perspective view of the cooling unit 35 according to the second embodiment. In the figure, the same parts as in FIG. 3 are assigned the same reference numerals and detailed explanations thereof will be omitted.
The cooling unit 35 includes four heat transfer units 31 and a cooling plate 36.
Unlike the first embodiment in which the four heat transfer parts 31 are connected by the connection parts 32 and 33, the cooling part 35 is in contact with the cooling plate 36 with the end faces 31 a of the four heat transfer parts 31. The heat transfer section 31 contains, for example, water as a liquid, as in the first embodiment.
The heat transfer portion 31 and the cooling plate 36 may communicate with each other in the internal space, or may not communicate with each other.

FIG. 7 is an explanatory view of the case where the internal space is communicated in the present embodiment. The storage element 1 is inserted between the heat transfer units 31, and water W is accommodated in the heat transfer units 31 and the cooling plate 36.
When the central storage element 1 generates heat, the water in the heat transfer section 31 in contact with the storage element 1 takes vaporization heat from the storage element 1 and evaporates as in the first embodiment, and the storage element 1 is rapidly cooled. Ru. The amount of water in the heat transfer section 31 decreases. The generated steam flows to the other heat transfer unit 31 through the cooling plate 36, and the water generated by the condensation flows to the heat transfer unit 31 with a reduced amount of water. Water also absorbs heat to cool the storage element 1, and the generated water vapor circulates as described above. The cooling plate 36 also cools the side surface of the storage element 1 in contact.

  When the internal space is not communicated, when the storage element 1 generates heat, the water in the heat transfer unit 31 in contact with the storage element 1 takes vaporization heat from the storage element 1 and evaporates, and the storage element 1 is rapidly cooled . The generated steam is cooled by the cooling plate 36 and condensed to water. Water absorbs heat from the storage element 1 and is vaporized, whereby the storage element 1 is cooled.

  Also in the present embodiment, the conduction of heat to the storage element 1 adjacent to the generated storage element 1 is suppressed by the cooling unit 35 having a simple structure, and the heat transfer to the adjacent storage element 1 is also performed in a chained manner. Be suppressed.

  In addition, in the power storage device described above, each of the storage elements 1 is formed in a rectangular parallelepiped shape, and the cooling unit 35 is in contact with a surface different from the long side of each of the storage elements 1 with which the heat transfer portion 31 abuts. The cooling unit 36 is configured to cool the plurality of storage elements 1, and the cooling unit 35 is configured to be able to conduct heat between the cooling plate 36 and the heat transfer unit 31.

  According to the above configuration, heat is conducted between the cooling plate 36 and the heat transfer section 31, so that the heat is dissipated well. The liquid is vaporized and the generated gas is cooled and liquefied, and the liquid can again absorb heat from the storage element to cool the storage element 1.

  In the storage device described above, the cooling plate 36 and the heat transfer unit 31 are integrated so that the liquid or a gas obtained by vaporizing the liquid can circulate.

According to the above configuration, the gas generated by the vaporization of the liquid flows through the inside of the cooling plate 36 by thermal convection in one heat transfer section 31 in contact with the heated storage element 1 to the other heat transfer section 31. Flow. The gas is liquefied in the other heat transfer section 31 and flows to the one heat transfer section 31 to circulate the liquid.
Therefore, the liquid is reused to cool the storage element 1 and cools the storage element 1 efficiently.
Further, the temperature difference between one long side surface and the other long side surface of one storage element 1 is reduced, and the temperature difference between storage elements 1 is reduced. And, by the circulation of the gas and the liquid, it is possible to reduce the temperature difference between the plurality of storage elements 1 and to cool efficiently. Even when heat generation is not abnormal and occurs to a low degree, the heat transfer unit 31 properly dissipates the heat from the storage element 1 and the temperature difference between the storage elements 1 is reduced.

Third Embodiment
FIG. 8 is a perspective view of the cooling unit 37 according to the third embodiment. In the figure, the same parts as in FIG. 3 are assigned the same reference numerals and detailed explanations thereof will be omitted.
The cooling unit 37 according to the third embodiment has a configuration in which the bottom surfaces 31 b of the four heat transfer units 31 of the cooling unit 30 according to the first embodiment are in contact with the cooling plate 38. Similar to the first embodiment, the heat transfer section 31 contains, for example, water as a liquid.
The heat transfer portion 31 and the cooling plate 38 do not communicate with each other in the internal space. The cooling plate 38 may be configured to be cooled by a cooling device (not shown).

  When the central storage element 1 generates heat, the water in the heat transfer section 31 in contact with the storage element 1 evaporates as in the first embodiment, and the storage element 1 is cooled by the vaporization heat at the time of evaporation. The generated steam flows through the other heat transfer unit 31, and the water generated by condensation flows to the heat transfer unit 31 with a small amount of water. The cooling plate 38 cools the bottom of the storage element 1 and also cools the heat transfer portion 31. The water in the heat transfer portion 31 in contact with the storage element 1 also absorbs heat from the storage element 1 and evaporates to cool the storage element 1.

  Also in the present embodiment, similarly to the first embodiment and the second embodiment, the conduction of heat to the storage element 1 adjacent to the generated storage element 1 is suppressed by the cooling unit 37 having a simple structure, and further adjacent Heat transfer to the storage element 1 in a continuous manner is suppressed.

Fourth Embodiment
FIG. 9 is a perspective view of the cooling unit 39 according to the fourth embodiment. In the figure, the same parts as in FIG. 3 are assigned the same reference numerals and detailed explanations thereof will be omitted.
In the present embodiment, an internal pressure release valve 34 is provided at the center of the upper surface of each heat transfer section 31.

FIG. 10 is an explanatory view for explaining cooling when the rupture valve 20 of the central storage element 1 is opened. When the internal pressure of the storage element 1 reaches a predetermined value or more, the rupture valve 20 is opened, and the component of the volatilized electrolyte is released to the outside.
The internal pressure release valve 34 of the adjacent heat transfer section 31 is opened by the heat of the storage element 1. FIG. 10 shows the case where the internal pressure release valves 34 of the two adjacent heat transfer parts 31 are opened.
The vapor is ejected from the internal pressure release valve 34, and the heat storage element 1 is cooled by the heat of vaporization at this time.
Since the heat transfer unit 31 is connected by the connection units 32 and 33, the liquid in the heat transfer unit 31 in which the internal pressure release valve 34 is not open is always supplied, and the cooling of the storage element 1 is continued.
If the amount of the liquid can cool one storage element 1 in total, the decrease in energy density can be minimized, and the chain of superheated states can be efficiently suppressed.

The present invention is not limited to the contents of the embodiments described above, and various modifications can be made within the scope of the claims. That is, an embodiment obtained by combining technical means appropriately modified within the scope of the claims is also included in the technical scope of the present invention.
In the first to third embodiments, the case where the storage element 1 is a lithium ion secondary battery is described, but the storage element 1 is not limited to a lithium ion secondary battery. The storage element 1 may be another secondary battery having an organic solvent, may be a primary battery, or may be an electrochemical cell such as a capacitor.
The power storage device according to the present invention can be particularly suitably used as a power source for a vehicle. Further, the power storage device according to the present invention includes a power storage system (large-scale power storage system, household small-scale power storage system), a distributed power supply system combined with natural energy such as sunlight or wind power, a power supply system for railways, unmanned carrier It can also be suitably used in industrial applications such as power supply systems for (AGV).

DESCRIPTION OF SYMBOLS 1 Storage element 2 Cover plate 3 Case main body 4 Positive electrode terminal 8 Negative electrode terminal 6, 10 Gasket 11 Case 20 Bursting valve 30, 35, 37, 39 Cooling part 31 Heat transfer part 32, 33 Connection part 34 Internal pressure release valve 36, 38 Cooling Plate 40 Case 100 Power Storage Device

Claims (5)

A plurality of storage elements,
And a cooling unit for cooling the storage element,
The cooling unit contains a liquid, is disposed between at least the storage elements, and includes a heat transfer unit which is in contact with the storage elements and cools the storage elements by heat of vaporization of the liquid. apparatus.   The power storage device according to claim 1, further comprising: a connecting portion connecting a plurality of the heat transfer portions such that the internal space is in communication. Each of the storage elements is formed in a rectangular shape;
The cooling unit includes a cooling plate that cools the plurality of storage elements in contact with a surface different from the long side of the storage element on which the heat transfer unit abuts.
The power storage device according to claim 1, wherein the cooling unit is configured to be able to conduct heat between the cooling plate and the heat transfer unit.   The power storage device according to claim 3, wherein the cooling plate and the heat transfer portion are integrated such that the liquid or a gas obtained by vaporizing the liquid can circulate.   The electricity storage according to any one of claims 1 to 4, wherein the cooling unit has an internal pressure release valve that releases the internal pressure when the internal pressure of the cooling unit exceeds a predetermined pressure. apparatus.

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