Power storage device

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

[Technical Field]

[0001] The present invention relates to an energy storage device including a plurality of energy storage elements. [Background technology]

[0002] Chargeable and dischargeable energy storage elements are used in a variety of devices, including mobile phones and automobiles. In particular, electric vehicles (EVs) and plug-in hybrid electric vehicles (PHEVs), which use electrical energy as their power source, require large amounts of energy and are therefore equipped with large-capacity energy storage devices that comprise multiple energy storage elements.

[0003] In such an energy storage device, if the temperature of one of the energy storage elements rises excessively for some reason, even if it is not under normal use, the heat from this energy storage element will be conducted to the adjacent energy storage elements, causing the adjacent energy storage elements to heat up. If this causes the active material of the electrode of the adjacent energy storage element to heat up to or above its self-heating temperature, this adjacent energy storage element will also become overheated due to self-heating, which will further heat the adjacent energy storage element, potentially causing a chain reaction in which many energy storage elements become overheated.

[0004] When using an energy storage element with a metal case covered with a resin film, if the energy storage element becomes overheated, the resin film melts and the metal cases come into contact with each other, promoting heat conduction and resulting in a chain reaction of overheating. In particular, when the metal case is used as an electrode or when the metal case has an abnormal potential due to some abnormality, the case may come into electrical contact with the case of an adjacent energy storage element, causing an abnormal current to flow in the adjacent energy storage element, which may lead to an overheating state.

[0005] Japanese Patent Application Laid-Open No. 2015-195149 discloses a technique for suppressing the conduction of heat from an energy storage element to adjacent energy storage elements. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-195149 Summary of the Invention [Problem to be solved by the invention]

[0007] In the electricity storage device of Patent Document 1, heat conduction between the electricity storage elements is suppressed by partition members made of mica aggregate material. In recent years, there has been a demand for further increases in the capacity of energy storage elements and energy storage devices. Increasing the capacity of an energy storage element results in a significant increase in the energy and heat released from the energy storage element when it becomes overheated. While increasing the thickness of the air gap or partition between the energy storage elements can improve thermal insulation, these methods result in a decrease in the energy density of the energy storage device. Therefore, new measures are needed to prevent a chain reaction of overheating between energy storage elements without decreasing the energy density.

[0008] An object of the present invention is to provide an electricity storage device that can effectively prevent a chain reaction of overheating between electricity storage elements. [Means for solving the problem]

[0009] The energy storage device of the present invention comprises a plurality of energy storage elements and a cooling unit that cools the energy storage elements, and the cooling unit is characterized in that it contains a liquid, is arranged at least between the energy storage elements, and has a heat transfer unit that is in contact with the energy storage elements and cools the energy storage elements by the heat of vaporization of the liquid. [Effects of the Invention]

[0010] According to the present invention, in the heat transfer section that comes into contact with the heated energy storage elements, the liquid contained therein absorbs heat from the energy storage elements and evaporates, thereby efficiently cooling the energy storage elements. Since the heat transfer section is disposed at least between the energy storage elements, heat conduction to the energy storage elements adjacent to the heated energy storage element is suppressed, and in the case of three or more energy storage elements, heat transfer to adjacent energy storage elements in a chain reaction is further suppressed. In other words, a chain reaction of overheating between the energy storage elements is efficiently prevented. Furthermore, since the liquid is contained within the heat transfer section, after vaporization, it is liquefied within the heat transfer section and reused for cooling the electricity storage elements, thereby efficiently cooling the electricity storage elements. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. [Figure 2] 1 is a perspective view of a power storage device according to a first embodiment. [Figure 3] FIG. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. [Figure 5] 10 is an explanatory diagram for explaining cooling by a cooling unit when an electric storage element generates heat; FIG. [Figure 6] FIG. 10 is a perspective view of a cooling unit according to a second embodiment. [Figure 7] FIG. 10 is an explanatory diagram illustrating a case where the internal spaces are connected to each other in the second embodiment. [Figure 8] FIG. 11 is a perspective view of a cooling unit according to a third embodiment. [Figure 9] FIG. 10 is a perspective view of a cooling unit according to a fourth embodiment. [Figure 10] FIG. 10 is an explanatory diagram illustrating cooling when the burst valve of the central storage element is opened. DETAILED DESCRIPTION OF THE INVENTION

[0012] The present invention will now be described in detail with reference to the drawings showing embodiments thereof. (First embodiment) 1 is a perspective view of an energy storage device 1 according to the first embodiment. Below, a case where the energy storage device 1 is a lithium ion secondary battery will be described, but the energy storage device 1 is not limited to a lithium ion secondary battery. The energy storage element 1 includes a case 11 having a cover 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 assembly (not shown).

[0013] The case 11 is made of a metal such as aluminum, an aluminum alloy, or stainless steel, or a synthetic resin, has a rectangular parallelepiped shape, and contains an electrode body and an electrolyte (not shown).

[0014] The positive electrode terminal 4 has a shaft portion that passes through the cover plate 2 and a plate portion provided at one end of the shaft portion. The gasket 6 is made of a synthetic resin such as polyphenylene sulfide (PPS) or polypropylene (PP). The positive electrode terminal 4 has an inner surface of its plate portion and a shaft portion covered by the gasket 6, and is provided to penetrate the cover plate 2 in an insulated state.

[0015] The negative electrode terminal 8 has a shaft portion that penetrates the cover plate 2 and a plate portion provided at one end of the shaft portion. The inner surface of the plate portion and the shaft portion of the negative electrode terminal 8 are covered with a gasket 10, and the negative electrode terminal 8 is provided to penetrate the cover plate 2 in an insulated state.

[0016] The electrode body may be a laminated type having a main body formed into a rectangular parallelepiped shape by alternately stacking a plurality of positive and negative electrode plates with separators interposed therebetween, and a positive electrode tab and a negative electrode tab extending from the main body toward the cover plate 2. The positive electrode tab is connected to a positive electrode terminal 4 via a current collector. The negative electrode tab is connected to a negative electrode terminal 8 via a current collector. The electrode assembly may be a wound type obtained by winding a positive electrode plate and a negative electrode plate with a separator interposed therebetween in a flat shape. The electrode body is preferably a laminated type, which reduces swelling during charging and discharging (swelling of the exterior body, such as a metal case like case 11 or a pouch case with a laminated structure). Since the exterior body does not swell much, it is possible to prevent the exterior body from pressing against the heat transfer section 31 during normal use.

[0017] The positive electrode plate is a positive electrode substrate foil, which is a plate-shaped (sheet-shaped) or long strip-shaped metal foil made of aluminum, aluminum alloy, etc., on which a positive electrode active material layer is formed. The negative electrode plate is a negative electrode substrate foil, which is a plate-shaped (sheet-shaped) or long strip-shaped metal foil made of copper, copper alloy, etc., on which a negative electrode active material layer is formed. The separator is a microporous sheet made of 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, any known material can be used as long as it is a positive electrode active material or a negative electrode active material that can absorb and release lithium ions.

[0018] Examples of the positive electrode active material that can be used include polyanion compounds such as LiMPO4, LiM2SiO4, and LiMBO3 (wherein M is one or more transition metal elements selected from Fe, Ni, Mn, Co, etc.), spinel compounds such as lithium titanate and lithium manganese oxide, and lithium transition metal oxides such as LiMO2 (wherein M is one or more transition metal elements selected from Fe, Ni, Mn, Co, etc.).

[0019] Examples of the negative electrode active material 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 alloy), alloys capable of absorbing and releasing lithium, carbon materials (e.g., graphite, non-graphitizable carbon, easily graphitizable carbon, low-temperature fired carbon, amorphous carbon, etc.), metal oxides, and lithium metal oxides (Li4Ti5O 12 etc.), polyphosphate compounds, etc.

[0020] Rupture valve 20 has a rupture portion 200 formed by partially reducing the plate thickness. When the internal pressure of energy storage element 1 increases, burst valve 20 ruptures along rupture portion 200, forming a tongue-shaped portion that springs up outward, forming an opening in cover plate 2.

[0021] FIG. 2 is a perspective view of the electricity storage device 100 according to this embodiment, and FIG. 3 is a perspective view of the cooling unit 30. As shown in FIG. The energy storage device 100 includes a plurality of energy storage elements 1, a cooling unit 30 that cools the energy storage elements 1, and a case 40 that houses the energy storage elements 1 and the cooling unit 30. In Fig. 2, three energy storage elements 1 are housed, but the number of energy storage elements 1 is not limited to three. The case 40 is box-shaped and made of an insulating material such as synthetic resin. The case 40 positions the energy storage element 1 and the cooling unit 30 in predetermined positions and protects them from impact. The case 40 is provided with external electrode terminals (not shown) for charging with electricity from the outside and discharging electricity to the outside.

[0022] The cooling section 30 may be made of a metal such as aluminum that has good thermal conductivity and heat resistance, and may be subjected to an insulating treatment such as forming an insulating film on the surface. As shown in FIG. 3 , the cooling unit 30 includes a plate-shaped heat transfer unit 31, connecting units 32 and 33 that connect the heat transfer units 31, and an internal pressure release valve 34. The two heat transfer units 31 are interposed between the long side surfaces of adjacent energy storage elements 1, and the two heat transfer units 31 abut against the outer long side surfaces of the energy storage elements 1 at both ends. Here, the long side surfaces are provided so as to extend upward from the long sides of the bottom surfaces of the energy storage elements 1 in FIG. 1 and are the side surfaces that have 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 units 31. The number of heat transfer units 31 may correspond to the number of energy storage elements 1. The heat transfer units 31 are interposed between the energy storage elements 1 and are further provided so as to abut against the outer long side surfaces of the energy storage elements 1 at both ends. The outer heat transfer portions 31 can be omitted. For example, if there are five energy storage elements 1, four heat transfer portions 31 are arranged between the energy storage elements 1, and the four heat transfer portions 31 are connected by connecting portions 32, 33. The long sides of the outer energy storage elements 1 abut against the sides of the case 40. Providing outer heat transfer portions 31 provides better cooling efficiency.

[0023] FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. The internal pressure release valve 34 is a circular groove, and as shown in Figure 4, the thickness of the bottom of the groove is thinner than the thickness of other parts. The internal pressure release valve 34 is formed by cutting, press working, etc. When forming the internal pressure release valve 34 by cutting, a device capable of cutting curved surfaces, such as a three-dimensional NC, is used. When forming the internal pressure release valve 34 by press working, it is formed by stamping using a mold with protrusions.

[0024] The heat transfer section 31 is hollow, and a liquid is contained in the internal space. The liquid is preferably non-flammable, has a large heat of vaporization, is corrosion-resistant, and does not generate toxic gases. The liquid preferably contains water. Water is harmless, has little corrosiveness, is non-flammable, and is highly safe. The liquid may be fluid or gel-like, and may contain refrigerants such as HFC refrigerants and inert gas solutions. The boiling point may be adjusted by mixing water with components other than water. The amount of liquid to be stored is set based on the internal volume of the heat transfer section 31 and the connecting sections 32 and 33, the expected heat generation temperature of the energy storage element 1, the volume of the liquid when vaporized, etc., so as not to damage the heat transfer section 31.

[0025] The upper portions of one end of the long side surfaces of adjacent heat transfer sections 31 are connected by a connecting section 32. The connecting section 32 is hollow and configured so that gas inside the connected heat transfer sections 31 flows through the connecting section 32. The lower portions of one end of the long side of adjacent heat transfer sections 31 are connected by a connecting section 33. The connecting section 33 is hollow and configured so that the liquid in the connected heat transfer sections 31 flows through the connecting section 33. That is, the internal spaces of the adjacent heat transfer portions 31, connecting portions 32, and connecting portions 33 are in communication with each other.

[0026] FIG. 5 is an explanatory diagram for explaining cooling by the cooling unit 30 when the energy storage element 1 generates heat. It is assumed that water W is contained as a liquid in cooling section 30, and that central energy storage element 1 generates heat. Heat is conducted from the heated energy storage element 1 to the heat transfer portions 31 on both sides, and the water W in the heat transfer portions 31 evaporates (FIG. 5A). When the water W evaporates, the heat of vaporization is large, and the energy storage element 1 is rapidly cooled by an endothermic reaction. The amount of water W in the heat transfer portions 31 on both sides of the heated energy storage element 1 decreases due to evaporation.

[0027] The water vapor in the heat transfer section 31 flows upward due to thermal convection and moves to the outer heat transfer section 31, which has a lower temperature, through the connecting sections 32, 32 (FIG. 5B). The water vapor condenses in the outer heat transfer section 31, and the amount of water W in the outer heat transfer section 31 increases.

[0028] The water W flows to the inner heat transfer section 31 via the connecting section 33 by the amount increased in the outer heat transfer section 31, and the amount of water in the four heat transfer sections 31 becomes equal (FIG. 5C). The circulated water W absorbs heat generated by the energy storage element 1 again, vaporizes, and circulates in the same manner as above.

[0029] When water is used as the liquid, water evaporates at 100°C and has a large heat of vaporization, so the heat of the energy storage elements 1 can be kept below a hundred and several tens of degrees Celsius, which may cause malfunctions. In other words, the energy storage device 100 can rapidly cool the energy storage elements 1 in a highly safe state.

[0030] The above-described energy storage device 100 comprises a plurality of energy storage elements 1 and a cooling unit 30 that cools the energy storage elements 1, and the cooling unit 30 has a heat transfer unit 31 that contains a liquid, is arranged at least between the energy storage elements 1, is in contact with the long sides of the energy storage elements 1, and cools the energy storage elements 1 by the heat of vaporization of the liquid.

[0031] According to the above configuration, the heat transfer section 31 in contact with the heated energy storage element 1 absorbs the heat of vaporization when the contained liquid evaporates, thereby effectively cooling the energy storage element 1. Since the heat transfer section 31 is disposed at least between the energy storage elements 1, heat conduction to the energy storage element 1 adjacent to the heated energy storage element 1 is suppressed, and further, heat transfer to the adjacent energy storage elements 1 in a chain reaction is suppressed. In other words, a chain reaction of overheating between the energy storage elements 1 is effectively prevented. The structure for cooling the energy storage elements 1 is simple, and the energy storage elements 1 can be cooled even when a small amount of heat is generated. Furthermore, since the liquid is contained within the heat transfer section 31, after vaporization, it is liquefied within the heat transfer section 31 and is reused for cooling the energy storage elements 1, thereby cooling the energy storage elements 1 efficiently.

[0032] In the above-described electricity storage device 100, the cooling section 30 has connecting sections 32 and 33 that connect the plurality of heat transfer sections 31 so that the internal spaces thereof communicate with each other.

[0033] According to the above configuration, the liquid in one heat transfer section 31 that is in contact with the heated energy storage element 1 is vaporized, and the resulting gas flows through the connecting sections 32 and 33 by thermal convection and to the other heat transfer section 31. The gas is liquefied in the other heat transfer section 31 and flows to the one heat transfer section 31, and the liquid circulates. Therefore, the liquid is reused to cool the electric storage elements 1, and the electric storage elements 1 are cooled efficiently. Furthermore, the temperature difference between the long side of one energy storage element 1 that contacts one heat transfer section 31 and the long side that contacts the other heat transfer section 31 is reduced, thereby reducing the temperature difference between the energy storage elements 1. The circulation of gas and liquid reduces the temperature difference between the multiple energy storage elements 1, allowing for efficient cooling. Even when a low level of heat generation occurs that is not abnormal, the heat from the energy storage elements 1 is effectively dissipated by the heat transfer section 31, reducing the temperature difference between the energy storage elements 1.

[0034] In the above-described electricity storage device 100, 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.

[0035] According to the above configuration, when the amount of evaporation of the liquid is large and the internal pressure of the cooling unit 30 exceeds a predetermined pressure, the internal pressure release valve 34 opens and the gas is released to the outside. This prevents the cooling unit 30 from expanding due to the gas and pressing against the energy storage element 1. If a flammable gas is present, the liquid is mixed with the gas to prevent ignition.

[0036] Even if an end energy storage element 1 generates heat instead of the center, the heat is absorbed by the heat transfer section 31 in the same manner as above, and the energy storage element 1 is rapidly cooled. The long side of the adjacent energy storage element 1 that faces the heated energy storage element 1 is also rapidly cooled, suppressing heat transfer from the heated energy storage element 1 and preventing a chain reaction of overheating between the energy storage elements. The structure of the cooling section 30 is not limited to the structure shown in Fig. 3. A connecting section may be provided by having a rectangular tube pass through the upper and lower parts of each of the four heat transfer sections 31 at one end in the longitudinal direction.

[0037] (Second embodiment) 6 is a perspective view of a 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 unit 35 includes four heat transfer members 31 and a cooling plate 36. Unlike the first embodiment in which the four heat transfer parts 31 are connected by the connecting parts 32 and 33, the cooling part 35 has end faces 31a of the four heat transfer parts 31 abutting against the cooling plate 36. As in the first embodiment, the heat transfer parts 31 contain liquid, such as water. The internal spaces of the heat transfer portion 31 and the cooling plate 36 may or may not be in communication with each other.

[0038] 7 is an explanatory diagram of a case where the internal spaces are connected in this embodiment. Energy storage devices 1 are inserted between heat transfer portions 31, and water W is contained in heat transfer portions 31 and cooling plates . When the central energy storage element 1 generates heat, as in the first embodiment, the water in the heat transfer portion 31 that contacts the energy storage element 1 absorbs the heat of vaporization from the energy storage element 1 and evaporates, rapidly cooling the energy storage element 1. The amount of water in this heat transfer portion 31 decreases. The generated water vapor flows to the other heat transfer portions 31 via the cooling plate 36, and water generated by condensation flows to the heat transfer portion 31 with the reduced amount of water. The water also absorbs heat and cools the energy storage element 1, and the generated water vapor circulates as described above. The cooling plate 36 also cools the side surfaces of the energy storage element 1 that it contacts.

[0039] If the internal spaces are not connected, when the energy storage element 1 generates heat, the water in the heat transfer portion 31 that contacts the energy storage element 1 absorbs the heat of vaporization from the energy storage element 1 and evaporates, rapidly cooling the energy storage element 1. The generated water vapor is cooled by the cooling plate 36 and condenses into water. The water absorbs heat from the energy storage element 1 and evaporates, and the energy storage element 1 is cooled.

[0040] In this embodiment, too, the cooling section 35 with a simple structure suppresses heat conduction to adjacent storage elements 1 from the heated storage element 1, and further suppresses heat transfer to adjacent storage elements 1 in a chain reaction.

[0041] In addition, in the above-mentioned energy storage device, each of the energy storage elements 1 is formed in a rectangular parallelepiped shape, the cooling section 35 is provided with a cooling plate 36 that contacts a surface other than the long side on which the heat transfer section 31 of each of the energy storage elements 1 abuts, and cools the multiple energy storage elements 1, and the cooling section 35 is configured to allow heat to be conducted between the cooling plate 36 and the heat transfer section 31.

[0042] According to the above configuration, heat is conducted between the cooling plate 36 and the heat transfer portion 31, and thus heat is dissipated well. The gas generated by evaporation of the liquid is cooled and liquefied, and the liquid absorbs heat from the energy storage elements 1 again, thereby cooling the energy storage elements 1.

[0043] In the above-described electricity storage device, the cooling plate 36 and the heat transfer section 31 are integrated so that the liquid or the gas obtained by vaporizing the liquid can circulate.

[0044] According to the above configuration, the liquid in one heat transfer section 31 that is in contact with the heated energy storage element 1 is evaporated, and the resulting gas flows through the cooling plate 36 by thermal convection and to the other heat transfer section 31. The gas is liquefied in the other heat transfer section 31 and flows to the one heat transfer section 31, and the liquid circulates. Therefore, the liquid is reused to cool the energy storage elements 1, and the energy storage elements 1 are cooled efficiently. Furthermore, the temperature difference between one long side surface and the other long side surface of one energy storage element 1 is reduced, thereby reducing the temperature difference between the energy storage elements 1. The circulation of gas and liquid reduces the temperature difference between the multiple energy storage elements 1, enabling efficient cooling. Even when a small amount of heat is generated that is not abnormal, the heat transfer section 31 effectively dissipates the heat from the energy storage elements 1, reducing the temperature difference between the energy storage elements 1.

[0045] (Third embodiment) 8 is a perspective view of a cooling section 37 according to the third embodiment. In the figure, the same parts as those in FIG. 3 are given the same reference numerals and detailed description thereof will be omitted. The cooling section 37 of the third embodiment has a configuration in which the bottom surfaces 31b of the four heat transfer sections 31 of the cooling section 30 of the first embodiment are in contact with a cooling plate 38. As in the first embodiment, the heat transfer sections 31 contain liquid, such as water. The internal spaces of the heat transfer section 31 and the cooling plate 38 are not in communication with each other. The cooling plate 38 may be configured to be cooled by a cooling device (not shown).

[0046] When the central energy storage element 1 generates heat, as in the first embodiment, the water in the heat transfer portion 31 that contacts the energy storage element 1 evaporates, and the heat of vaporization that occurs during evaporation cools the energy storage element 1. The generated water vapor flows through the other heat transfer portions 31, and water generated by condensation flows to the heat transfer portion 31 with the least amount of water. The cooling plate 38 cools the bottom surface of the energy storage element 1 and also cools the heat transfer portion 31. The water in the heat transfer portion 31 that contacts the energy storage element 1 absorbs heat from the energy storage element 1 and evaporates, cooling the energy storage element 1.

[0047] In this embodiment, as in the first and second embodiments, the cooling section 37 has a simple structure, which suppresses heat conduction to adjacent storage elements 1 from the heated storage element 1, and further suppresses heat transfer to adjacent storage elements 1 in a chain reaction.

[0048] (Fourth embodiment) 9 is a perspective view of a cooling section 39 according to the fourth embodiment. In the figure, the same parts as those in FIG. 3 are given the same reference numerals and detailed description thereof will be omitted. In this embodiment, an internal pressure release valve 34 is provided in the center of the upper surface of each heat transfer portion 31.

[0049] 10 is an explanatory diagram illustrating cooling when the burst valve 20 of the central energy storage element 1 is opened. When the internal pressure of the energy storage element 1 reaches a predetermined value or more, the burst valve 20 opens and the volatilized components of the electrolyte are released to the outside. The heat from the energy storage elements 1 opens the internal pressure release valves 34 of the adjacent heat transfer sections 31. Fig. 10 shows a case where the internal pressure release valves 34 of two adjacent heat transfer sections 31 are open. Steam is ejected from the internal pressure release valve 34, and the heat of vaporization at this time cools the electric storage elements 1. Since the heat transfer parts 31 are connected by the connecting parts 32 and 33, the liquid in the heat transfer parts 31 whose internal pressure release valves 34 are not open is constantly supplied, and the energy storage elements 1 are continuously cooled. If the amount of liquid is sufficient to cool one energy storage element 1 in total, the decrease in energy density can be minimized and the chain reaction of overheating can be efficiently suppressed.

[0050] The present invention is not limited to the contents of the above-described embodiment, and various modifications are possible within the scope of the claims. In other words, embodiments obtained by combining technical means modified appropriately within the scope of the claims are also included in the technical scope of the present invention. In the first to third embodiments, the energy storage element 1 is described as a lithium ion secondary battery, but the energy storage element 1 is not limited to a lithium ion secondary battery. The energy storage element 1 may be another secondary battery containing an organic solvent, a primary battery, or 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 vehicles. The power storage device according to the present invention can also be suitably used in industrial applications such as power storage systems (large-scale power storage systems, small-scale home power storage systems), distributed power supply systems that combine natural energy such as solar power and wind power, power supply systems for railways, and power supply systems for automated guided vehicles (AGVs). [Explanation of symbols]

[0051] 1 Storage element 2 Cover plate 3 Case body 4 Positive terminal 8 Negative terminal 6, 10 Gasket 11 cases 20 Burst Valve 30, 35, 37, 39 Cooling section 31 Heat transfer section 32, 33 Connection part 34 Internal pressure release valve 36, 38 Cooling plate 40 cases 100 Electricity storage device

Claims

1. A first storage element; a second storage element disposed in a first direction of the first storage element; a cooling unit that cools the first storage element and the second storage element, The cooling unit contains a liquid, a heat transfer portion disposed between the first energy storage element and the second energy storage element in the first direction and in contact with the first energy storage element and the second energy storage element; a connecting portion that contacts a surface of the first storage element and the second storage element that faces a second direction that intersects with the first direction, an end portion of the heat transfer portion in a third direction intersecting the first direction and the second direction is connected to the connecting portion; a central portion of the heat transfer portion in the third direction is not connected to the connecting portion; Energy storage device.

2. The first storage element has a rupture valve on a surface facing the third direction, the end in the third direction includes an end opposite to a surface on which the burst valve is disposed; The power storage device according to claim 1 .

3. The end in the third direction further includes an end on a face side on which the rupture valve is arranged. The power storage device according to claim 2 .

4. The heat transfer unit cools the first storage element and the second storage element by heat of vaporization of the liquid. The electricity storage device according to any one of claims 1 to 3.

5. The heat transfer portion and the connecting portion are formed so that the liquid or the gas evaporated from the liquid can circulate. The electricity storage device according to any one of claims 1 to 4.

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