JP2022179667A - power storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: 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

COPYRIGHT: (C)2023,JPO&INPIT

Description

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

2. Description of the Related Art Rechargeable/dischargeable power storage elements are used in various devices such as mobile phones and automobiles. Vehicles powered by electrical energy, such as electric vehicles (EVs) and plug-in hybrid electric vehicles (PHEVs), require a large amount of energy. there is

In such a power storage device, if the temperature of any one power storage element rises excessively for some reason, although it is not in a normal use state, the heat of this power storage element is conducted to the adjacent power storage element, thereby The element is heated. As a result, when the active material of the electrode of the adjacent storage element is heated to a temperature higher than the self-heating temperature, the adjacent storage element is also overheated due to self-heating, and further heats the adjacent storage element. A large number of storage elements may become overheated.

In the case of using a power storage element with a metal case covered with a resin film, when the power storage element is overheated, the resin film melts and the metal cases come into contact with each other, promoting heat conduction. chain is 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, the case of an adjacent storage element is electrically contacted to cause an abnormal current to flow to the adjacent storage element. overheating can occur.

Japanese Patent Application Laid-Open No. 2015-195149 discloses a technique for suppressing conduction of heat from a power storage element to adjacent power storage elements.

JP 2015-195149 A

In the power storage device of Patent Document 1, the heat conduction between the power storage elements is suppressed by the partition member formed of the mica aggregate material.
In recent years, there has been a demand for a further increase in the capacity of power storage elements and power storage devices. When the capacity of the storage element is increased, the energy and heat released from one storage element when it is overheated is also very large. The heat insulation can be improved by increasing the thickness of the air layer between the power storage elements and the partition member, but these methods reduce the energy density of the power storage device. Therefore, there is a demand for a new countermeasure capable of preventing a chain of overheated states between storage elements without lowering the energy density.

SUMMARY OF THE INVENTION An object of the present invention is to provide a power storage device capable of satisfactorily preventing a chain of overheated states between power storage elements.

A power storage device according to the present invention includes a plurality of power storage elements and a cooling unit that cools the power storage elements. The cooling unit contains liquid, is disposed at least between the power storage elements, and is in contact with the power storage elements. and a heat transfer section that cools the electric storage element by the heat of vaporization of the liquid.

According to the present invention, in the heat transfer portion that contacts the heated storage element, the internal liquid absorbs heat from the storage element and evaporates, thereby cooling the storage element well. Since the heat transfer section is arranged at least between the storage elements, heat conduction to the storage elements adjacent to the storage element that generates heat is suppressed, and in the case of having three or more storage elements, the heat is transferred to the adjacent storage elements. is suppressed. That is, a chain of overheated states between the storage elements can be effectively prevented.
In addition, since the liquid is contained in the heat transfer section, after being vaporized, the liquid is liquefied in the heat transfer section and reused for cooling the power storage element, so that the power storage element is efficiently cooled.

It is a perspective view of an electrical storage element. 1 is a perspective view of a power storage device according to a first embodiment; FIG. It is a perspective view of a cooling part. FIG. 4 is a cross-sectional view taken along line IV-IV of FIG. 3; FIG. 4 is an explanatory diagram for explaining cooling by a cooling unit when an electric storage element generates heat; It is a perspective view of the cooling part which concerns on 2nd Embodiment. It is explanatory drawing when internal space is connected in 2nd Embodiment. It is a perspective view of the cooling part which concerns on 3rd Embodiment. It is a perspective view of the cooling part which concerns on 4th Embodiment. FIG. 10 is an explanatory diagram for explaining cooling when a rupture valve of a central storage element is opened;

BEST MODE FOR CARRYING OUT THE INVENTION 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 an electric storage device 1 according to the first embodiment. A case where the storage element 1 is a lithium ion secondary battery will be described below, but the storage element 1 is not limited to a lithium ion secondary battery.
The storage element 1 includes a case 11 having a lid plate 2 and a case body 3, a positive electrode terminal 4, a negative electrode terminal 8, gaskets 6 and 10, a burst valve 20, a current collector, and an electrode body (not shown).

The case 11 is made of a metal such as aluminum, an aluminum alloy, stainless steel, or 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 penetrating through the cover plate 2 and a plate provided at one end of the shaft.
The gasket 6 is made of 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 an insulated state in which the inner surface of the plate portion and the shaft portion are covered with a gasket 6 .

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

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 laminated with separators interposed therebetween to form a rectangular parallelepiped shape, and positive electrode tabs and negative electrode tabs extending from the main body toward the cover plate 2. may The positive electrode tab is connected to the positive electrode terminal 4 via the current collector. The negative electrode tab is connected to the negative electrode terminal 8 via the current collector. The electrode body may be of a winding type obtained by flatly winding a positive electrode plate and a negative electrode plate with a separator interposed therebetween.
The electrode assembly is more preferably of the laminated type, which causes less swelling due to charge/discharge (swelling of an exterior body such as a metal case such as the case 11 or a pouch case with a laminated structure). Since swelling of the exterior body is small, it is possible to prevent the exterior body from pressing the heat transfer section 31 during normal use.

The positive electrode plate is formed by forming a positive electrode active material layer on a positive electrode substrate foil, which is a plate-like (sheet-like) or long belt-like metal foil made of aluminum, an aluminum alloy, or the like. The negative electrode plate is formed by forming a negative electrode active material layer on a negative electrode substrate foil, which is a plate-like (sheet-like) or long belt-like metal foil made of copper, a copper alloy, or the like. The separator is a microporous sheet made of synthetic resin.
As the positive electrode active material used for the positive electrode active material layer or the negative electrode active material used for the negative electrode active material layer, any known positive electrode active material or negative electrode active material capable of intercalating and deintercalating lithium ions can be used as appropriate. .

Examples of positive electrode active materials include polyanion compounds such as LiMPO ₄ , LiM ₂ SiO ₄ , and LiMBO ₃ (where M is one or more transition metal elements selected from Fe, Ni, Mn, Co, etc.); Spinel compounds such as lithium oxide and lithium manganate, and lithium transition metal oxides such as LiMO2 (M is one or more transition metal elements selected from Fe, Ni, Mn, Co, etc.) can be used. can.

Examples of negative electrode active materials include lithium metal, lithium alloys (lithium-aluminum, lithium-silicon, lithium-lead, lithium-tin, lithium-aluminum-tin, lithium-gallium, and lithium metal-containing alloys such as Wood's alloys). In addition, alloys that can absorb and release lithium, carbon materials (e.g., graphite, non-graphitizable carbon, easily graphitizable carbon, low-temperature fired carbon, amorphous carbon, etc.), metal oxides, lithium metal oxides (Li ₄ Ti ₅ O ₁₂ , etc.), polyphosphoric acid compounds, and the like.

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

FIG. 2 is a perspective view of the power storage device 100 according to this embodiment, and FIG. 3 is a perspective view of the cooling unit 30. As shown in FIG.
The power storage device 100 includes a plurality of power storage elements 1 , a cooling unit 30 that cools the power storage elements 1 , and a case 40 that houses the power storage elements 1 and the cooling unit 30 . Although three power storage elements 1 are accommodated in FIG. 2, the number of power storage elements 1 is not limited to three.
The case 40 has a box shape and is made of an insulating material such as synthetic resin. The case 40 arranges the electric storage device 1 and the cooling section 30 at predetermined positions and protects them from impact. The case 40 is provided with external electrode terminals (not shown) for charging electricity from the outside and discharging electricity to the outside.

The cooling part 30 may be made of a metal such as aluminum having good thermal conductivity and heat resistance, and may be subjected to insulation treatment such as by forming an insulating film on the surface.
As shown in FIG. 3 , the cooling section 30 includes a plate-shaped heat transfer section 31 , connecting sections 32 and 33 that connect the heat transfer section 31 , and an internal pressure release valve 34 . The two heat transfer portions 31 are interposed between the long side surfaces of the adjacent storage elements 1, and the two heat transfer portions 31 are in contact with the outer long side surfaces of the storage elements 1 at both ends. Here, the long side surface is provided so as to extend upward from the long side of the bottom surface of the storage element 1 in FIG. 1, and is 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 sections 31 may be provided corresponding to the number of storage elements 1 . The heat transfer part 31 is interposed between the storage elements 1 and is provided so as to abut on the outer 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 electric storage elements 1 is five, four heat transfer parts 31 are arranged between the electric storage elements 1 and the four heat transfer parts 31 are connected by connecting parts 32 and 33 . The long side surface of the outer storage element 1 is brought into contact with the side surface of the case 40 . Cooling efficiency is better when 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 other portions. The internal pressure release valve 34 is formed by cutting, pressing, or the like. When forming the internal pressure release valve 34 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 press working, it is formed by stamping with a mold having projections.

The heat transfer part 31 is hollow, and the internal space contains a liquid. The liquid is preferably nonflammable, has a large heat of vaporization, has corrosion resistance, and does not generate toxic gas. Preferably the liquid comprises water. Water is harmless, less corrosive, non-flammable, and highly safe. The liquid may be fluid or gel-like, and may contain refrigerants such as solutions of HFC-based refrigerants and inert gases. You may adjust a boiling point by mixing components other than water and water.
The capacity of the liquid is determined based on the internal volume of the heat transfer section 31 and the connecting sections 32 and 33, the assumed heat generation temperature of the power storage element 1, the volume when the liquid is vaporized, and the like, and the heat transfer section 31 is not damaged. set as

The upper ends of the long sides of adjacent heat transfer portions 31 are connected by a connecting portion 32 . The connecting portion 32 is hollow, and is configured such that the gas in the heat transfer portion 31 connected thereto flows through the connecting portion 32 .
The lower ends of the long side surfaces of adjacent heat transfer portions 31 are connected by a connecting portion 33 . The connecting portion 33 is hollow, and configured so that the liquid in the heat transfer portion 31 connected thereto flows through the connecting portion 33 .
That is, the adjacent heat transfer portion 31, connecting portion 32, and connecting portion 33 communicate with each other in internal space.

FIG. 5 is an explanatory diagram for explaining cooling by the cooling unit 30 when the power storage element 1 generates heat.
It is assumed that the cooling unit 30 contains water W as a liquid, and the power storage element 1 in the center generates heat.
Heat is conducted from the heat-generated electric storage element 1 to the heat transfer portions 31, 31 on both sides, and the water W in the heat transfer portion 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 portions 31 on both sides of the heat-generating power storage element 1 decreases due to evaporation.

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

The amount of water W increased in the outer heat transfer section 31 flows to the inner heat transfer section 31 via the connection section 33, and the water amount of the four heat transfer sections 31 becomes equal (Fig. 5C). The circulated water W also absorbs the heat generated by the storage element 1, vaporizes, and circulates in the same manner as described above.

When water is used as the liquid, water evaporates at 100° C. and has a large heat of vaporization. Therefore, the heat of the storage element 1 can be suppressed below 100-odd degrees, which may cause a malfunction. That is, the power storage device 100 can rapidly cool the power storage element 1 in a highly safe state.

The power storage device 100 described above includes a plurality of power storage elements 1 and a cooling unit 30 that cools the power storage elements 1. The cooling unit 30 contains liquid and is disposed at least between the power storage elements 1. 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, the heat transfer portion 31 in contact with the heat-generating storage element 1 removes the heat of vaporization when the contained liquid evaporates, so that the storage element 1 is well cooled. Since the heat transfer part 31 is arranged at least between the storage elements 1, the heat conduction to the storage element 1 adjacent to the storage element 1 that generates heat is suppressed, and the heat is continuously transferred to the adjacent storage elements 1. is suppressed. That is, a chain of overheated states between the storage elements 1 can be effectively prevented.
The structure for cooling the power storage element 1 is simple, and the power storage element 1 can be cooled even when a low degree of heat generation occurs.
Further, since the liquid is contained in the heat transfer section 31, after being vaporized, the liquid is liquefied in the heat transfer section 31 and reused for cooling the storage element 1, thereby cooling the storage element 1 efficiently.

In the power storage device 100 described above, the cooling section 30 has connecting sections 32 and 33 that connect the plurality of heat transfer sections 31 so that the internal spaces communicate with each other.

According to the above configuration, in one heat transfer section 31 in contact with the heat-generating power storage element 1, gas generated by vaporization of the liquid flows through the connection sections 32 and 33 due to thermal convection, and the other heat transfer section Flow 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 for cooling the storage element 1, and the storage element 1 is efficiently cooled.
In addition, the temperature difference between the long side surface in contact with one heat transfer portion 31 and the long side surface in contact with the other heat transfer portion 31 in one power storage element 1 is reduced, and the temperature difference between the power storage elements 1 is reduced. is reduced. By circulating the gas and liquid, the temperature difference between the plurality of power storage elements 1 can be reduced and the power storage elements 1 can be efficiently cooled. Even when heat generation of a low degree, which is not abnormal, occurs, the heat transfer portion 31 satisfactorily dissipates the heat from the storage elements 1, and the temperature difference between the storage elements 1 is reduced.

In the power storage device 100 described above, the cooling unit 30 has 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 a large amount of liquid evaporates and the internal pressure of the cooling unit 30 exceeds a predetermined pressure, the internal pressure release valve 34 is opened to release the gas to the outside. This prevents the expansion of the cooling unit 30 by the gas and the pressing of the electric storage element 1 . If combustible gas is present, ignition is prevented by mixing with the gas.

Even when the energy storage element 1 at the end rather than the center generates heat, the heat is absorbed by the heat transfer section 31 in the same manner as described above, and the energy storage element 1 is rapidly cooled. The long sides of the adjacent storage elements 1 facing the heated storage elements 1 are also rapidly cooled, the heat transfer from the heated storage elements 1 is suppressed, and the chain of overheated states between the storage elements is prevented.
In addition, the structure of the cooling part 30 is not limited to the structure of FIG. A connecting portion may be provided so that a square tube penetrates the upper portion and the lower portion of each one end in the longitudinal direction of the four heat transfer portions 31 .

(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 those in FIG. 3 are denoted by the same reference numerals, and detailed description thereof will be omitted. The cooling section 35 includes four heat transfer sections 31 and a cooling plate 36 .
Unlike the first embodiment in which the four heat transfer portions 31 are connected by the connection portions 32 and 33 , the cooling portion 35 has the end surfaces 31 a of the four heat transfer portions 31 in contact with the cooling plate 36 . The heat transfer section 31 contains, for example, water as a liquid, as in the first embodiment.
The internal spaces of the heat transfer section 31 and the cooling plate 36 may communicate with each other, or may not communicate with each other.

FIG. 7 is an explanatory diagram of the case where the internal spaces are communicated in this embodiment. The power storage element 1 is inserted between the heat transfer portions 31 , and water W is accommodated in the heat transfer portions 31 and the cooling plate 36 .
When the central storage element 1 generates heat, the water in the heat transfer portion 31 in contact with the storage element 1 absorbs the heat of vaporization from the storage element 1 and evaporates, thereby rapidly cooling the storage element 1, as in the first embodiment. be. The amount of water in this heat transfer section 31 is reduced. The generated water vapor flows through the cooling plate 36 to the other heat transfer section 31, and the water generated by condensation flows to the heat transfer section 31 where the amount of water is reduced. The water also absorbs heat to cool the storage element 1, and the resulting water vapor circulates as described above. Cooling plate 36 also cools the side surface of power storage element 1 that is in contact with it.

When the internal space is not communicated, when the storage element 1 generates heat, the water in the heat transfer portion 31 contacting the storage element 1 takes the heat of vaporization from the storage element 1 and evaporates, so that the storage element 1 is rapidly cooled. . The resulting water vapor is cooled by cooling plate 36 and condensed into water. Water absorbs heat from the storage element 1 and evaporates, thereby cooling the storage element 1 .

Also in the present embodiment, the cooling unit 35 having a simple structure suppresses the conduction of heat to the adjacent storage element 1 to the storage element 1 that generates heat, and furthermore, the chain transfer of heat to the adjacent storage element 1 is avoided. Suppressed.

In addition, in the power storage device described above, each of the power storage elements 1 is formed in a rectangular parallelepiped shape, and the cooling portion 35 is in contact with a surface different from the long side surface of each of the power storage elements 1 with which the heat transfer portion 31 abuts. A cooling plate 36 for cooling the plurality of power storage elements 1 is provided, and the cooling section 35 is configured to allow heat to be conducted between the cooling plate 36 and the heat transfer section 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 satisfactorily. The gas generated by the vaporization of the liquid is cooled and liquefied, and the liquid absorbs heat from the power storage element again, so that the power storage element 1 can be cooled.

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

According to the above configuration, in one heat transfer section 31 in contact with the heat-generating power storage element 1 , gas generated by vaporization of the liquid flows through the cooling plate 36 by thermal convection, and flows 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 for cooling the storage element 1 and efficiently cools the storage element 1 .
In addition, the temperature difference between one long side and the other long side of one storage element 1 is reduced, and the temperature difference between storage elements 1 is reduced. By circulating the gas and liquid, the temperature difference between the plurality of power storage elements 1 can be reduced and the power storage elements 1 can be efficiently cooled. Even when heat generation of a low degree, which is not abnormal, occurs, the heat transfer portion 31 satisfactorily dissipates the heat from the storage elements 1, and the temperature difference between the storage elements 1 is reduced.

(Third Embodiment)
FIG. 8 is a perspective view of the cooling section 37 according to the third embodiment. In the figure, the same parts as those in FIG. 3 are denoted by the same reference numerals, and detailed description thereof will be omitted.
The cooling portion 37 of the third embodiment has a configuration in which the bottom surfaces 31b of the four heat transfer portions 31 of the cooling portion 30 of the first embodiment are in contact with the cooling plate 38 . As in the first embodiment, the heat transfer section 31 contains, for example, water as a liquid.
The internal spaces of the heat transfer section 31 and the cooling plate 38 are not communicated with each other. 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, and the storage element 1 is cooled by the heat of vaporization, as in the first embodiment. The generated water vapor flows through other heat transfer sections 31, and the water generated by condensation flows into the heat transfer section 31 where the amount of water is small. Cooling plate 38 cools the bottom surface of storage element 1 and cools heat transfer section 31 . The water in the heat transfer portion 31 in contact with the power storage element 1 also absorbs heat from the power storage element 1 and evaporates, thereby cooling the power storage element 1 .

Also in the present embodiment, as in the first and second embodiments, the cooling section 37 having a simple structure suppresses the conduction of heat to the adjacent storage elements 1 that generate heat, chain-like heat transfer to the storage element 1 is suppressed.

(Fourth embodiment)
FIG. 9 is a perspective view of the cooling section 39 according to the fourth embodiment. In the figure, the same parts as those in FIG. 3 are denoted by the same reference numerals, and detailed description thereof will be omitted.
In this 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 diagram illustrating cooling when the rupture valve 20 of the central storage element 1 is opened. When the internal pressure of the electric storage element 1 reaches a predetermined value or higher, the burst valve 20 opens and the volatilized components of the electrolytic solution are released to the outside.
The heat of the storage element 1 opens the internal pressure release valve 34 of the adjacent heat transfer section 31 . FIG. 10 shows the case where the internal pressure release valves 34 of two adjacent heat transfer sections 31 are opened.
Steam is ejected from the internal pressure release valve 34, and the heat of vaporization at this time cools the power storage element 1. As shown in FIG.
Since the heat transfer portion 31 is connected by the connection portions 32 and 33 , the liquid in the heat transfer portion 31 to which the internal pressure release valve 34 is not opened is always supplied, and the cooling of the electric storage element 1 is continued.
If the amount of this liquid is enough to cool one power storage element 1 in total, the decrease in energy density can be minimized and the chain of overheating can be efficiently suppressed.

The present invention is not limited to the contents of the above-described embodiments, and various modifications are possible within the scope of the claims. That is, the technical scope of the present invention also includes embodiments obtained by combining technical means appropriately modified within the scope of the claims.
In the first to third embodiments, the storage element 1 is a lithium ion secondary battery, but the storage element 1 is not limited to a lithium ion secondary battery. The storage element 1 may be another secondary battery containing an organic solvent, a primary battery, or an electrochemical cell such as a capacitor.
INDUSTRIAL APPLICABILITY A power storage device according to the present invention can be particularly suitably used as a power source for a vehicle. In addition, the power storage device according to the present invention includes power storage systems (large-scale power storage systems, small-scale power storage systems for home use), distributed power systems combined with natural energy such as sunlight and wind power, power systems for railways, and automated guided vehicles. It can also be suitably used for industrial applications such as power supply systems for (AGV).

Reference Signs List 1 storage element 2 cover plate 3 case main body 4 positive terminal 8 negative terminal 6, 10 gasket 11 case 20 burst valve 30, 35, 37, 39 cooling section 31 heat transfer section 32, 33 connecting section 34 internal pressure release valve 36, 38 cooling Plate 40 Case 100 Power storage device

Claims (5)

a plurality of power storage elements;
A cooling unit that cools the storage element,
The power storage device, wherein the cooling unit includes a heat transfer unit that contains a liquid, is arranged at least between the power storage elements, is in contact with the power storage elements, and cools the power storage elements by the heat of vaporization of the liquid. Device. 2. The power storage device according to claim 1, further comprising a connecting portion that connects a plurality of said heat transfer portions so that internal spaces communicate with each other. each of the storage elements is formed in a rectangular parallelepiped shape,
The cooling unit includes a cooling plate that cools the plurality of power storage elements by contacting a surface of each power storage element that is different from the long side surface with which the heat transfer part abuts,
3. The power storage device according to claim 1, wherein the cooling section is configured to allow heat to be conducted between the cooling plate and the heat transfer section. 4. The power storage device according to claim 3, wherein the cooling plate and the heat transfer section are integrated so that the liquid or gas obtained by vaporizing the liquid can circulate. The power 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. Device.

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