power storage device

Abstract

The present application provides a kind of electric power storage device.The electric power storage device (100) has: a plurality of electric power storage elements (1), and cooling module (30) for cooling electric power storage element (1).Cooling module (30) has cooling part (31), which is at least configured between electric power storage element (1), built-in flame retardant, using the heat absorption of the vaporization of flame retardant to cool electric power storage element (1).In the cooling part (31) in contact with the electric power storage element (1) of heat generation, using the vaporization heat of built-in flame retardant vaporization, electric power storage element (1) is preferably cooled, and the chain of overheated state between electric power storage element (1) is prevented.

Description

TECHNICAL FIELD

[0001] The present application relates to a power storage device having a plurality of power storage elements. BACKGROUND

[0002] Power storage elements capable of charge and discharge are used in various devices such as mobile phones, automobiles, and the like. Among them, vehicles such as electric vehicles (EV) or plug-in hybrid electric vehicles (PHEV) that use electric power as a power source require a large amount of energy, and therefore, a large-capacity power storage device having a plurality of power storage elements is mounted.

[0003] In such a power storage device, in a case where the temperature of an arbitrary power storage element excessively increases in a state other than a normal use state due to some cause, the adjacent power storage element is warmed by heat conduction from the power storage element. Thus, when the active material of the electrode of the adjacent power storage element is warmed to a self-heating temperature or higher, the adjacent power storage element also enters an overheating state due to self-heating, and further warms the adjacent power storage element thereof, possibly causing a large number of power storage elements to enter an overheating state in a chain reaction.

[0004] In a case where a power storage element in which a metal case is covered with a resin film is used, when the power storage element enters an overheating state, the resin film melts, and the metal cases contact each other to promote heat conduction, as a result of which, a chain reaction of an overheating state is easily caused. In particular, in a case where the metal case is used as an electrode, and in a case where the metal case has an abnormal potential due to some abnormality, the adjacent power storage element can be electrically contacted with the case to cause an abnormal current to flow in the adjacent power storage element, thereby causing an overheating state.

[0005] A technique for suppressing heat conduction from a power storage element to an adjacent power storage element has been disclosed in Patent Document 1.

[0006] In a case where the power storage element is a nonaqueous electrolyte secondary battery, as a nonaqueous electrolyte, a nonaqueous electrolyte in which an electrolyte such as lithium hexafluorophosphate (LiPF6) is dissolved in a nonaqueous solvent in which ethylene carbonate is a main constituent component is widely known. The above nonaqueous solvent is generally volatile and flammable. Therefore, it is necessary to suppress ignition in a power storage device.

[0007] It has been disclosed in Patent Document 2 that a nonaqueous electrolyte is made nonflammable by containing a noncyclic fluorinated ether having at least one -CF2H group at a terminal, a cyclic carbonate compound having a carbon-carbon π bond, and a sultone in the nonaqueous electrolyte.

[0008] It has been disclosed in Patent Document 3 that a nonaqueous electrolyte is made nonflammable by containing a fluorinated phosphate ester having a side chain of 3 or less carbon atoms and / or a fluorinated chain carbonate, and by making the proportion of the above nonaqueous electrolyte in a solvent 15 to 30 mass%.

[0009] Prior Art Documents

[0010] Patent Documents

[0011] Patent Document 1: Japanese Patent Application Publication No. 2015-195149

[0012] Patent Document 2: Japanese Patent No. 5092416

[0013] Patent Document 3: Japanese Patent No. 5842873 SUMMARY

[0014] PROBLEMS TO BE SOLVED BY THE INVENTION

[0015] In the power storage device of Patent Document 1, heat conduction between power storage elements is suppressed by a spacer member formed of mica integrated material.

[0016] In recent years, there is a demand for further increasing the capacity of power storage elements and power storage devices. When the capacity of a power storage element is increased, the energy and heat released from the power storage element when the power storage element is in an overheated state are also very large. Although the thermal insulation property can be improved by increasing the thickness of the air layer or the spacer member between power storage elements, in the above-described manner, the energy density of the power storage device is reduced. Therefore, a new countermeasure is needed that can prevent the chain of overheated states between power storage elements without reducing the energy density.

[0017] In order to prevent the power storage device from catching fire, in order for the nonaqueous electrolyte of the nonaqueous electrolyte secondary battery to exhibit sufficient flame retardancy, a large amount of fluorinated carbonate or the like needs to be mixed, but there is a limit to the amount of fluorinated carbonate or the like to be added in order to obtain good battery characteristics.

[0018] An object of the present application is to provide a power storage device that can prevent the chain of overheated states between power storage elements and can suppress catching fire.

[0019] TECHNICAL SOLUTION FOR SOLVING THE PROBLEMS

[0020] The power storage device of the first aspect of the present application has a plurality of power storage elements, and a cooling portion that is disposed at least between the power storage elements and in which a flame retardant is built in, and that cools the power storage elements using the heat of vaporization of the flame retardant.

[0021] The power storage device of the second aspect of the present application has a plurality of power storage elements, and a cooling portion that cools the power storage elements, the cooling portion having a heat conducting portion in which a liquid is built in, and being disposed at least between the power storage elements and in contact with the power storage elements, and cooling the power storage elements using the heat of vaporization of the liquid.

[0022] EFFECTS OF THE INVENTION

[0023] According to the first aspect of the present application, in the cooling portion, the built-in fire retardant absorbs heat from the power storage element and evaporates, thereby cooling the power storage element well. Since the cooling portion is disposed at least between the power storage elements, heat conduction to the power storage element adjacent to the power storage element that generates heat can be suppressed. Thus, a chain of overheating states among the power storage elements can be prevented.

[0024] Since the fire retardant is built in the cooling portion, after vaporization, it is liquefied in the cooling portion and reused in the cooling of the power storage element, thereby cooling the power storage element efficiently.

[0025] In a case where the flammable component is released from the power storage element after the fire retardant is released from the cooling portion and vaporized, the flammable component is fire-retardantized by the fire retardant, and ignition in the power storage device can be prevented or suppressed.

[0026] According to the second aspect of the present application, in the heat conducting portion that contacts the power storage element that generates heat, the built-in liquid absorbs heat from the power storage element and evaporates, thereby cooling the power storage element well. Since the heat conducting portion is disposed at least between the power storage elements, heat conduction to the power storage element adjacent to the power storage element that generates heat can be suppressed, and in a case where there are three or more power storage elements, heat conduction to the adjacent power storage element in a chain can be further suppressed. That is, a chain of overheating states among the power storage elements can be well prevented.

[0027] In addition, since the liquid is built in the heat conducting portion, after vaporization, it is liquefied in the heat conducting portion and reused in the cooling of the power storage element, thereby cooling the power storage element efficiently. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 is a perspective view of a power storage element.

[0029] Figure 2 is a perspective view of a power storage device of a first embodiment.

[0030] Figure 3 is a perspective view of a cooling module.

[0031] Figure 4 is a IV-IV line sectional view of Figure 3

[0032] Figure 5 is an explanatory view that explains cooling using a cooling module in a case where the power storage element generates heat.

[0033] Figure 6 is an explanatory view that explains suppression of ignition using a fire retardant.

[0034] Figure 7 is a perspective view of a cooling module of a second embodiment.

[0035] ​Figure 8 is a diagram illustrating a case where the internal space is communicated in the second embodiment.

[0036] Figure 9 is a diagram illustrating suppression of ignition by the flame retardant.

[0037] Figure 10 is a perspective view of the cooling module of the third embodiment.

[0038] Figure 11 is a perspective view of the power storage device of the fourth embodiment.

[0039] Figure 12 is a sectional view showing a modification of the cooling portion (heat conducting portion). DETAILED DESCRIPTION

[0040] Hereinafter, the present application will be specifically described on the basis of the drawings showing the embodiments.

[0041] (First Embodiment)

[0042] Figure 1 is a perspective view of the power storage element 1. Although the case where the power storage element 1 is a lithium ion secondary battery will be described below, the power storage element 1 is not limited to the lithium ion secondary battery.

[0043] The power storage element 1 has a case 11 having a lid plate 2 and a case main body 3, a positive electrode terminal 4, a negative electrode terminal 8, gaskets 6, 10, a burst valve 20, a current collector, and an electrode body (not shown).

[0044] The case 11 is formed of, for example, a metal such as aluminum, an aluminum alloy, stainless steel, or a synthetic resin, and is formed in a rectangular parallelepiped shape, and accommodates the electrode body and an electrolyte solution (not shown). Alternatively, the case can be a soft pack case using a laminate sheet.

[0045] The positive electrode terminal 4 has a shaft portion that penetrates the lid plate 2, and a plate portion provided at one end of the shaft portion.

[0046] The positive electrode terminal 4 is covered by the gasket 6 from the inner surface of the plate portion and the shaft portion, and is provided so as to penetrate the lid plate 2 in an insulating state.

[0047] The negative electrode terminal 8 has a shaft portion that penetrates the lid plate 2, and a plate portion provided at one end of the shaft portion. The negative electrode terminal 8 is covered by the gasket 10 from the inner surface of the plate portion and the shaft portion, and is provided so as to penetrate the lid plate 2 in an insulating state.

[0048] The electrode body can also be of a laminate type, and has a main body formed in a rectangular parallelepiped shape by alternately stacking a plurality of positive electrode plates and negative electrode plates via separators, and positive and negative electrode tabs extending from the main body toward the lid plate 2. 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.

[0049] The electrode body can also be a jelly-roll type obtained by winding the positive electrode plate and the negative electrode plate into a flat shape via the separator.

[0050] The electrode body is preferably a laminate in which expansion (expansion of an outer packaging body such as a metal case of the case 11, a soft package case, or the like) is small with charge / discharge cycles. Because the expansion of the outer packaging body is small with charge / discharge cycles, the outer packaging body can be inhibited from pressing the cooling portion 31 described later at the time of ordinary use.

[0051] The positive electrode plate is formed with a positive electrode active material layer on a plate-shaped (sheet-shaped) or long belt-shaped metal foil, i.e., a positive electrode base material foil, which is made of aluminum, an aluminum alloy, or the like. The negative electrode plate is formed with a negative electrode active material layer on a plate-shaped (sheet-shaped) or long belt-shaped metal foil, i.e., a negative electrode base material foil, which is made of copper, a copper alloy, or the like. The separator is a microporous sheet made of a synthetic resin.

[0052] 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, only a positive electrode active material or a negative electrode active material capable of absorbing and releasing lithium ions can be appropriately used, and known materials can be used.

[0053] As the positive electrode active material, for example, polyanion compounds such as LiMPO4, Li2MSiO4, LiMBO3 (M is one or two or more kinds of transition metal elements selected from Fe, Ni, Mn, Co, and the like), spinel compounds such as lithium titanate and lithium manganese oxide, lithium transition metal oxides such as LiMO2 (M is one or two or more kinds of transition metal elements selected from Fe, Ni, Mn, Co, and the like), and the like can be used.

[0054] As the negative electrode active material, for example, in addition to lithium metal, lithium alloy (lithium-aluminum, lithium-silicon, lithium-lead, lithium-tin, lithium-aluminum-tin, lithium-gallium, and lithium-containing metal alloy such as Wood's alloy), alloys capable of absorbing and releasing lithium, carbon materials (for example, graphite, hard graphitizable carbon, easy graphitizable carbon, low-temperature calcined carbon, amorphous carbon, and the like), metal oxides (SiO and the like), lithium metal oxides (Li4Ti5O 12 and the like), and polyphosphoric acid compounds can be exemplified.

[0055] The burst valve 20 has a rupture portion 200 formed by partially reducing the plate thickness. When the internal pressure of the power storage element 1 rises, the rupture portion 200 ruptures, and a tongue-shaped portion is formed, which is elastically projected outward to form an opening in the cover plate 2.

[0056] Figure 2 is a perspective view of the power storage device 100 of the present embodiment, Figure 3 is a perspective view of the cooling module 30.

[0057] The electricity storage device 100 has a plurality of electricity storage elements 1 arranged in a first direction, a cooling module (cooling section) 30 that cools the electricity storage elements 1, and a case 40 that houses the electricity storage elements 1 and the cooling module 30. In Figure 2 the number of the electricity storage elements 1 is not limited to three.

[0058] The case 40 is formed in a box shape, for example, by an insulating material such as synthetic resin. The case 40 arranges the electricity storage elements 1, the cooling module 30, and the like at a prescribed position and protects them from collision. An external electrode terminal (not shown) for charging the electricity storage elements 1 from the outside and discharging electricity from the electricity storage elements 1 to the outside is provided in the case 40.

[0059] The cooling module 30 can also be formed of a metal such as aluminum that has good thermal conductivity and heat resistance, and can also be subjected to an insulating treatment in which an insulating film or the like is formed on the surface.

[0060] As shown in Figure 3 , the cooling module 30 has plate-shaped cooling sections (thermal conductive sections) 31, linking sections 32, 33 that link the cooling sections 31, and an internal pressure relief valve 34. Two of the cooling sections 31 intervene between the long sides of the electricity storage elements 1 adjacent in the first direction, and the other two of the cooling sections 31 abut against the long sides of the electricity storage elements 1 on the outside at both ends in the first direction. Here, the long side refers to Figure 1 a side that is disposed upward from the long side of the bottom surface of the electricity storage element 1 and has the largest area among the sides. The internal pressure relief valve 34 is provided in the central portion of the upper surface of each of the cooling sections 31.

[0061] The cooling sections 31 can be provided in correspondence with the number of the electricity storage elements 1, can intervene between the electricity storage elements 1, and can also be provided so as to abut against the long sides of the electricity storage elements 1 on the outside at both ends.

[0062] The position at which the internal pressure relief valve 34 is provided is not limited to the central portion of the upper surface of the cooling section 31.

[0063] The internal pressure relief valve 34 can be provided at a position at which it can effectively prevent ignition when the fire retardant L described later is sprayed. As shown in Figure 2 , the burst valve 20 of the electricity storage element 1 and the internal pressure relief valve 34 of the cooling section 31 can be oriented in the same direction. The internal pressure relief valve 34 can be oriented upward in the direction of gravity.

[0064] The cooling section 31 is hollow.

[0065] The fire retardant L is housed in the cooling section 31.

[0066] The upper portion of one end of the long side of the adjacent cooling portion 31 is connected by a connecting portion 32. The connecting portion 32 is hollow and configured to allow the gas in the connected cooling portion 31 to flow through the connecting portion 32.

[0067] The lower portion of one end of the long side of the adjacent cooling portion 31 is connected by a connecting portion 33. The connecting portion 33 is hollow and configured to allow the fire retardant L in the connected cooling portion 31 to flow through the connecting portion 33.

[0068] That is, the internal spaces of the cooling portion 31, the connecting portion 32, and the connecting portion 33 are communicated.

[0069] Note that the cooling portion 31 on the outer side can be omitted. For example, in the case where the number of the power storage elements 1 is five, four cooling portions 31 are arranged between the power storage elements 1 and connected by the connecting portions 32 and 33. The long side of the power storage element 1 on the outer side is brought into abutment with the side surface of the case 40. The cooling efficiency of the power storage element 1 provided with the cooling portion 31 on the outer side is further improved.

[0070] Figure 4 is Figure 3 an IV-IV line sectional view.

[0071] As shown in Figure 4 , the internal pressure relief valve 34 is a circular groove, and the thickness of the bottom of the groove is thinner than that of the other portions. The internal pressure relief valve 34 is formed by cutting processing, press processing, or the like. In the case where the internal pressure relief valve 34 is formed by cutting processing, a device capable of cutting a curved surface such as three-dimensional NC is used. In the case where the internal pressure relief valve 34 is formed by press processing, the stamp is formed by being pressed by a mold having a protrusion.

[0072] The fire retardant L exhibits flame retardancy with respect to a gas having flammability by vaporization. The fire retardant L is preferably a fire retardant having a large heat of vaporization, corrosion resistance, and no toxic gas generation.

[0073] The fire retardant L preferably contains at least any one of an acyclic fluorinated ether, a fluorinated phosphate ester, and a phosphazene derivative. They have high flame retardancy by vaporization.

[0074] The acyclic fluorinated ether is more preferably represented by the following formula (1).

[0075] CX 3-j H j -(CF x H 2-x ) m -O-(CF y H 2-y ) n -CF 3-k H k …(1)

[0076] (Where, X is F or CF3. J, k, m, n, x, y are integers, namely 0≦j≦3, 0≦k≦3, 1≦m≦3, 0≦n≦1, 0≦x≦2, 0≦y≦2, and contain at least one fluorine atom).

[0077] Specifically, examples include HCF2CF2CH2OCF2CF2H, HCF2CF2OCH2CF3, CF3CF2CH2OCF2CF2H, HCF2CF2CH2OCHF2, CF3CF2CH2OCF2H, (CF3)2CHCF2OCF2H, CF3CHFCF2CH2OCHF2, etc., alone or in mixtures of two or more of the above, but are not limited to these.

[0078] Fluorinated phosphate esters are more preferably represented by the following formula (2).

[0079] [Chemistry 1]

[0080]

[0081] (Where j, k, l, m, n, o, x, y, z are integers, and are 0≦j≦3, 0≦k≦3, 0≦l≦3, 0≦m≦1, 0≦n≦1, 0≦o≦1, 0≦x≦2, 0≦y≦2, 0≦z≦2, and contain at least one fluorine atom).

[0082] Phosphazene derivatives are more preferably represented by the following formula (3).

[0083] [Chemistry 2]

[0084]

[0085] (In the formula, R1 to R6 represent the same or different hydrogen atoms, halogen atoms, straight-chain or branched alkyl groups with 1 to 10 carbon atoms, alkyl groups with 1 to 10 carbon atoms replaced by fluorine atoms, alkoxy groups with 1 to 10 carbon atoms, and alkoxy groups with 1 to 10 carbon atoms replaced by fluorine atoms).

[0086] The phosphazene derivative is further preferably a fluorinated phosphazene derivative in which at least one of R1 to R6 is a fluorine atom, an alkyl group replaced by a fluorine atom, or an alkoxy group replaced by a fluorine atom.

[0087] Among fluorophosphazene derivatives, monoethoxypentafluorocyclotriphosphazene represented by the following formula 3 and monophenoxypentafluorocyclotriphosphazene represented by the following formula 4 are particularly preferred.

[0088]

Transformation 3

[0089]

[0090]

Chemistry 4

[0091]

[0092] The amount of flame retardant L stored is set based on the internal volume of the cooling section 31 and the connecting sections 32 and 33, the assumed heating temperature of the energy storage element 1, and the volume of the flame retardant L when it vaporizes, so as to prevent the cooling section 31 from being damaged.

[0093] Figure 5 This is an explanatory diagram illustrating the use of cooling module 30 to cool the energy storage element 1 when it generates heat.

[0094] The cooling module 30 contains a flame retardant L (or water as an alternative liquid), assuming that the central energy storage element 1 generates heat.

[0095] Heat is conducted from the heated energy storage element 1 to the cooling sections 31, 31 on both sides, and the flame retardant L in the cooling section 31 evaporates. Figure 5 A) The heat of vaporization is carried away during the evaporation of flame retardant L, which rapidly cools the energy storage element 1 through an endothermic reaction. The amount of flame retardant L in the cooling section 31 is reduced.

[0096] The gas inside the cooling section 31 flows upward through thermal convection and moves towards the cooler outer side of the cooling section 31 through the connecting parts 32, 32. Figure 5 B). The gas condenses in the outer cooling section 31, and the liquid volume of the flame retardant L in the outer cooling section 31 increases.

[0097] Flame retardant L flows into the inner cooling section 31 via the connecting part 33, correspondingly increasing the liquid volume in the outer cooling section 31, so that the liquid volume of flame retardant L in the four cooling sections 31 is equal. Figure 5 C). The flame retardant L, after cycling, absorbs the heat generated by the energy storage element 1 and vaporizes, undergoing the same cycle as described above.

[0098] Figure 6 This is an illustration showing how flame retardants can be used to suppress ignition.

[0099] When the temperature of the energy storage element 1 rises sharply, the heat absorbed from the energy storage element 1 increases, and the evaporation of the flame retardant L increases. When the internal pressure of the cooling section 31, which is in contact with the energy storage element 1, reaches a predetermined value, the internal pressure relief valve 34 of the cooling section 31 opens, and the vaporized flame retardant L is released to the outside, specifically to a second direction orthogonal to the first direction (e.g., upward in the direction of gravity). Figure 6 The text indicates that the internal pressure relief valves 34 of the cooling sections 31 on both sides of the energy storage element 1 are open, and the flame retardant L is released. The internal pressure relief valves 34 open when the internal pressure of the outer cooling section 31 also reaches a specified value.

[0100] In a case where the internal pressure of the power storage element 1 reaches a prescribed value or more, the burst valve 20 opens, and the flammable component of the evaporated electrolyte is released to the outside. The flammable component is rendered nonflammable by the flame retardant L, and ignition is prevented.

[0101] As described above, the power storage device 100 of the present embodiment has: a plurality of power storage elements 1; a cooling section 31 disposed at least between the power storage elements 1, in which a flame retardant L is built in, and which cools the power storage elements 1 using the heat of vaporization of the flame retardant L.

[0102] According to the above-described configuration, since the flame retardant L in the cooling section 31 that is in contact with the power storage element 1 that has generated heat takes away the heat of vaporization when vaporizing, the power storage element 1 is cooled well. Since the cooling section 31 is disposed at least between the power storage elements 1, heat conduction to the power storage element 1 adjacent to the power storage element 1 that has generated heat is suppressed. Even in a case where heat is conducted to the adjacent power storage element 1 without passing through the cooling section 31, the long side surface opposite the power storage element 1 that has generated heat is cooled by the cooling section 31. Thus, heat conduction of the power storage elements 1 in a chain is suppressed.

[0103] The cooling structure of the cooling module 30 is simple, and the power storage elements 1 can be cooled even when the heat generation is low.

[0104] Since the flame retardant L is built in the cooling section 31, after vaporizing, it is liquefied in the cooling section 31 and is used again in the cooling of the power storage elements 1, and the power storage elements 1 are effectively cooled.

[0105] In the above-described power storage device 100, the flame retardant L exhibits nonflammability with respect to a gas having flammability by vaporizing.

[0106] According to the above-described configuration, in a case where the flame retardant L absorbs heat from the power storage element 1 that has generated heat and vaporizes and is released from the internal pressure release valve 34, the flammable component released from the power storage element 1 is mixed, the flammable component is rendered nonflammable, and ignition is prevented in the power storage device 100.

[0107] In the above-described power storage device 100, the flame retardant L includes at least any one of a noncyclic fluorinated ether, a fluorinated phosphate ester, and a phosphazene derivative.

[0108] According to the above-described configuration, the flame retardant L has high nonflammability by vaporizing.

[0109] In the above-described power storage device 100, the cooling module 30 has a linking section that links a plurality of the cooling sections 31 in a manner in which the internal spaces communicate.

[0110] According to the above configuration, in one cooling section 31 that contacts the heat generating power storage element 1, the gas generated by vaporization of the fire retardant L flows to the other cooling section 31 through the connecting sections 32, 33 by thermal convection. The gas is liquefied in the other cooling section 31 and flows to the one cooling section 31, thereby circulating the fire retardant L.

[0111] Therefore, the fire retardant L can be reused in cooling of the power storage element 1, and the power storage element 1 can be effectively cooled.

[0112] Further, the heated gas flows from one cooling section 31 to the other cooling section 31 via the connecting sections 32, 33, whereby the temperature difference between the long side surface of one power storage element 1 that contacts the one cooling section 31 and the long side surface that contacts the other cooling section 31 is reduced, and the temperature difference between the power storage elements 1 is reduced. Moreover, by circulation of the gas and the fire retardant L, the temperature difference between the plurality of power storage elements 1 can be reduced, and cooling can be effectively performed. In the case where heat generation is low and not abnormal, the heat from the power storage element 1 can be better released by the cooling section 31, and the temperature difference between the power storage elements 1 can be reduced.

[0113] In the above power storage device 100, the cooling section 31 has an internal pressure relief valve 34 that releases the internal pressure of the cooling section 31 when the internal pressure exceeds a predetermined pressure.

[0114] According to the above configuration, in the case where the amount of vaporization of the fire retardant L increases and the internal pressure of the cooling section 31 exceeds a predetermined pressure, the internal pressure relief valve 34 opens and releases the gas to the outside. By releasing the gas, the cooling section 31 can be prevented from expanding and pressing the power storage element 1.

[0115] In the case where the temperature of the power storage element 1 sharply increases, the amount of heat absorption from the power storage element 1 increases, and the amount of vaporization of the fire retardant L increases. When the internal pressure reaches a predetermined value or more, the cooling section 31 is opened, and the vaporized fire retardant L is released to the outside. In the case where the internal pressure of the power storage element 1 reaches a predetermined value or more, the power storage element 1 is opened, and the flammable component of the evaporated electrolyte is released to the outside. The flammable component is rendered nonflammable by the fire retardant L, and ignition is prevented.

[0116] In the case where the power storage element 1 at the end portion, not the center, generates heat, heat is absorbed by the cooling section 31 as above, and the power storage element 1 is rapidly cooled. The long side surface of the adjacent power storage element 1 that opposes the power storage element 1 that generates heat is also rapidly cooled, and heat conduction from the power storage element 1 that generates heat is suppressed, and a chain of overheating states between the power storage elements is prevented.

[0117] Note that the configuration of the cooling module 30 is not limited to Figure 3The connecting portions can be provided so as to connect the upper and lower portions of each of the four ends of the square tube in the length direction of the cooling portions 31.

[0118] (Second Embodiment)

[0119] Figure 7 is a perspective view of the cooling module 35 of the second embodiment. The same parts as in Figure 3 the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

[0120] The cooling module 35 has four cooling portions 31 and a cooling plate 36.

[0121] In the second embodiment, the end surfaces 31a of the four cooling portions 31 abut against the cooling plate 36, unlike the first embodiment in which the cooling portions 31 are connected by the connecting portions 32, 33. The fire retardant L is housed in the cooling portions 31 as in the first embodiment.

[0122] The internal spaces of the cooling portions 31 and the cooling plate 36 can be communicated or not communicated.

[0123] Figure 8 is an explanatory view of the case where the internal spaces are communicated in the present embodiment. The power storage elements 1 are interposed between the cooling portions 31, and the fire retardant L is housed in the cooling portions 31 and the cooling plate 36.

[0124] In the case where the central power storage element 1 generates heat, the fire retardant L in the cooling portion 31 abutting against the power storage element 1 evaporates taking away the heat of vaporization from the power storage element 1, and the power storage element 1 is rapidly cooled. The liquid amount of the fire retardant L in the cooling portion 31 decreases. The generated gas flows to the other cooling portions 31 via the cooling plate 36, and the fire retardant L generated by condensation flows to the cooling portion 31 where the liquid amount of the fire retardant L has decreased. The fire retardant L absorbs heat again, and the power storage element 1 is cooled, and the generated gas is circulated as described above. The cooling plate 36 also cools the side surface of the power storage element 1 abutting against it.

[0125] In the case where the internal spaces are not communicated, when the power storage element 1 generates heat, the fire retardant L in the cooling portion 31 abutting against the power storage element 1 evaporates taking away the heat of vaporization from the power storage element 1, and the power storage element 1 is rapidly cooled. The generated gas is cooled by the cooling plate 36, and is condensed into the fire retardant L. The fire retardant L absorbs heat from the power storage element 1 and evaporates, and the power storage element 1 is cooled.

[0126] In the present embodiment, too, with the cooling module 35 of simple construction, heat conduction to the power storage element 1 adjacent to the power storage element 1 generating heat is suppressed, and further, heat conduction in a chain reaction to the adjacent power storage element 1 is suppressed.

[0127] Figure 9is an explanatory view showing suppression of ignition using the flame retardant L.

[0128] In the case where the temperature of the power storage element 1 sharply rises, the amount of heat absorption from the power storage element 1 increases, and the amount of evaporation of the flame retardant L increases. In the case where the internal pressure of the cooling portion 31 abutting against the power storage element 1 reaches a prescribed value or more, the internal pressure relief valve 34 opens, and the vaporized flame retardant L is released to the outside. In the case where the internal pressure of the power storage element 1 reaches a prescribed value or more, the burst valve 20 opens, and the flammable component of the electrolyte that has been volatilized is released to the outside. The flammable component is rendered nonflammable by the flame retardant L, and ignition is prevented.

[0129] The power storage device of the present embodiment is configured such that the power storage elements 1 are each formed in a cuboid shape, and a cooling plate 36 that cools the plurality of power storage elements 1 by making contact with the faces of the respective power storage elements 1 that are different from the long side faces opposite the cooling portion 31 is provided, and heat is conducted between the cooling plate 36 and the cooling portion 31.

[0130] According to the above configuration, because heat is conducted between the cooling plate 36 and the cooling portion 31, heat can be dissipated well. The gas generated by vaporization of the flame retardant L is cooled and liquefied, and the flame retardant L can be used again to cool the power storage element 1 by absorbing heat from the power storage element 1.

[0131] In the above-described power storage device, the cooling plate 36 and the cooling portion 31 are integrated so that the flame retardant L or the gas after vaporization of the flame retardant L can be circulated.

[0132] According to the above configuration, in one cooling portion 31 that is in contact with the power storage element 1 that has generated heat, the gas generated by vaporization of the flame retardant L passes through the cooling plate by thermal convection and flows to the other cooling portion 31. The gas is liquefied in the other cooling portion 31 and flows to the one cooling portion 31, thereby circulating the flame retardant L.

[0133] Therefore, the flame retardant L is reused in the cooling of the power storage element 1, and the power storage element 1 is effectively cooled.

[0134] In addition, the temperature difference between the one long side face of one power storage element 1 and the other long side face decreases, and the temperature difference between the power storage elements 1 decreases. Furthermore, by the circulation of the gas and the flame retardant L, the temperature difference between the plurality of power storage elements 1 can be reduced and cooling can be performed effectively. In the case where heat is generated at a low level that is not abnormal, the heat from the power storage element 1 can be released well by the cooling portion 31, and the temperature difference between the power storage elements 1 can be reduced.

[0135] The cooling module 37 of the third embodiment has a structure in which the bottom surface 31b of the four cooling portions 31 of the cooling module 30 of the first embodiment abuts against the cooling plate 38. The fire retardant L (not shown) is housed in the cooling portion 31 in the same manner as in the first embodiment.

[0136] The internal spaces of the cooling portion 31 and the cooling plate 38 are not communicated. The cooling plate 38 can also be configured to be cooled by a cooling device (not shown).

[0137] In the case where the central power storage element 1 generates heat, the fire retardant L in the cooling portion 31 abutting against the power storage element 1 evaporates, and the power storage element 1 is cooled by the heat of vaporization. The gas generated flows in the other cooling portions 31, and the fire retardant L generated by condensation flows to the cooling portion 31 in which the amount of the fire retardant L is small. The cooling plate 38 cools the bottom surface of the power storage element 1 and the cooling portion 31. The fire retardant L in the cooling portion 31 abutting against the power storage element 1 evaporates again by absorbing heat from the power storage element 1, and the power storage element 1 is cooled.

[0138] In the present embodiment, as in the first and second embodiments, the heat conduction to the power storage element 1 adjacent to the power storage element 1 that generates heat is suppressed by the cooling module 37 of a simple configuration, and further, the heat conduction to the adjacent power storage element 1 is suppressed in a chain reaction.

[0139] In the case where the temperature of the power storage element 1 sharply increases, the amount of heat absorption from the power storage element 1 increases, and the amount of evaporation of the fire retardant L increases. When the internal pressure reaches a predetermined value or more, the internal pressure relief valve 34 opens, and the fire retardant L after vaporization is released to the outside. In the case where the internal pressure of the power storage element 1 reaches a predetermined value or more, the burst valve 20 opens, and the flammable component of the electrolyte that has been volatilized is released to the outside.

[0140] The flammable component is rendered non-flammable by the fire retardant L, and ignition is prevented.

[0141] (Fourth Embodiment)

[0142] Figure 11 is a perspective view of the power storage device 101 of the fourth embodiment. The same parts as in the Figure 2 same parts as in the

[0143] The power storage device 101 differs from the power storage device 100 of the first embodiment in that it does not have the linking portions 32 and 33 that link the cooling portions 31. The cooling portions 31 are independently arranged between the power storage elements 1 or between the power storage elements 1 and the inner surface of the case 40. The fire retardant L (not shown) is housed in the cooling portion 31.

[0144] When the power storage element 1 generates heat, the fire retardant L in the cooling portion 31 abutting the power storage element 1 evaporates taking away the heat of vaporization from the power storage element 1, and the power storage element 1 is rapidly cooled. The generated gas is cooled by convection of the outside of the power storage device 101 and / or outside air and condensed into the fire retardant L. The fire retardant L is vaporized taking heat from the power storage element 1, and the power storage element 1 is cooled.

[0145] In the present embodiment, because the cooling portion 31 intervenes between the power storage elements 1, as in the first embodiment, the power storage element 1 that generates heat is cooled by the cooling portions 31 on both sides, and heat conduction to the adjacent power storage element 1 is suppressed. Even in the case where heat is conducted to the adjacent power storage element 1 without passing through the cooling portion 31, the long side surface facing the power storage element 1 that generates heat is cooled by the cooling portion 31. Therefore, heat conduction to the adjacent power storage element 1 in a chain reaction can be suppressed.

[0146] In the case where the temperature of the power storage element 1 sharply increases, the amount of heat absorption from the power storage element 1 increases, and the amount of evaporation of the fire retardant L increases. When the internal pressure reaches a predetermined value or more, the internal pressure relief valve 34 opens, and the fire retardant L after vaporization is released to the outside. In the case where the internal pressure of the power storage element 1 reaches a predetermined value or more, the burst valve 20 opens, and the flammable component of the electrolyte that has evaporated is released to the outside.

[0147] The flammable component is rendered non-flammable by the fire retardant L, and ignition is prevented.

[0148] The present application is not limited to the contents of the above-described embodiments, and various modifications can be made within the scope shown in the claims. That is, embodiments obtained by combining technical means appropriately modified within the scope shown in the claims are also included in the technical scope of the present application.

[0149] The cooling portion (heat conduction portion) arranged between the power storage elements can also be Figure 12The space member 131 is shown in such a manner. The space member 131 has: an inorganic paper sheet 100 in which inorganic fibers are the main body, a bag body 111 in which the inorganic paper sheet is housed in an internal space, and a fire retardant (or water) 112 that is impregnated in the inorganic paper sheet 100 and vaporizes due to an increase in temperature. The inorganic paper sheet 100 is a sheet formed by papermaking inorganic fibers, and has a void that holds a liquid between the inorganic fibers. The inorganic paper sheet 100 can also have a void ratio of 45% or more and 80% or less by volume. The "void ratio of the inorganic paper sheet" is a value calculated as a ratio of a difference between the volumes of the inorganic fibers and the inorganic paper sheet per unit area with respect to the volume of the inorganic paper sheet per unit area, using the thickness measured by a thickness gauge to calculate the volume of the inorganic paper sheet per unit area, and the volume of the inorganic fibers per unit area of the inorganic paper sheet is calculated from the specific gravity of the inorganic fibers and the weight of the inorganic fibers used per unit area of the inorganic paper sheet. The bag body 111 can also be formed by a laminated sheet in which an aluminum foil (metal layer) 113 and a resin film (resin layer) 114 are joined. The sheet forming the bag body 111 can also have a resin-made adhesive layer 15 on the inner surface of the metal layer 113 to enable adhesion by heat sealing. In the case where any one of the power storage elements 1 is in an overheated state, the fire retardant (or water) can also be vaporized and ejected from the bag body 111. The plurality of power storage elements 1 of the power storage device can also be interposed with the space member 131 and stacked in the first direction, and be held by the case 40 and a holding member such as a restriction member in a state of being pressed in the first direction.

[0150] In the first to fourth embodiments, the case where the positive electrode terminal 4 and the negative electrode terminal 8 of the power storage element 1 are arranged upward has been described, but the present application is not limited thereto. The cooling structure of the present application can also be applied in the case where the positive electrode terminal 4 and the negative electrode terminal 8 are arranged toward the side.

[0151] In addition, the case where the power storage element 1 is a lithium-ion secondary battery has been described, but the power storage element 1 is not limited to a lithium-ion secondary battery. The power storage element 1 can be another secondary battery having an organic solvent, can be a primary battery, or can be an electrochemical cell such as a capacitor.

[0152] The power storage device of the present application can be particularly suitably applied as a power source for a vehicle. In addition, the power storage device of the present application can also be suitably applied in industrial uses such as a power storage system (large-scale power storage system, small-scale power storage system for households), a distributed power system combined with natural energy such as solar power or wind power, a power source system for railways, and a power source system for an automated guided vehicle (AGV).

[0153] Explanation of Reference Signs

[0154] 1 storage element; 2 cover plate; 3 case main body; 4 positive electrode terminal; 8 negative electrode terminal; 6, 10 gasket; 11 case; 20 burst valve; 30, 35, 37 cooling module; 31 cooling portion; 32, 33 connecting portion; 34 internal pressure relief valve; 36, 38 cooling plate; 40 case; 100, 101 power storage device.

Claims

1. An electric power storage device, characterized by comprising: having: a plurality of power storage elements; a cooling section provided at least between the power storage elements, in which a fire retardant is built in, and in which the power storage elements are cooled using the heat of vaporization of the fire retardant, having a linking section that links a plurality of the cooling sections in a manner in which the internal spaces thereof communicate, an upper portion of one end of a long side of the cooling sections is linked by a hollow linking section, a lower portion of one end of a long side of the cooling sections is linked by a hollow linking section, in one cooling section that is in contact with the power storage elements that generate heat, gas generated by vaporization of the fire retardant passes through the hollow linking section that links an upper portion of one end of a long side of an adjacent cooling section and flows to the other cooling section.

2. The power storage device according to claim 1, wherein the fire retardant exhibits a flame retardant property by vaporization.

3. The power storage device according to claim 2, wherein the fire retardant contains at least any one of a non-cyclic fluorinated ether, a fluorinated phosphate ester, and a phosphazene derivative.

4. The power storage device according to any one of claims 1 to 3, wherein the cooling section has an internal pressure relief valve that releases the internal pressure when the internal pressure of the cooling section exceeds a predetermined pressure.

5. An electric power storage device characterized by comprising: having: a plurality of power storage elements; a cooling section provided at least between the power storage elements, in which a fire retardant is built in, and in which the power storage elements are cooled using the heat of vaporization of the fire retardant, the power storage elements are each formed in a cuboid shape, a cooling plate that contacts a surface of each of the power storage elements that is different from a long side surface to which the cooling section is attached and cools the plurality of power storage elements, is configured to be able to conduct heat between the cooling plate and the cooling section, the internal space of the cooling plate and the cooling section do not communicate.

6. The power storage device according to claim 5, wherein the cooling plate and the cooling section are integrated so that the fire retardant or gas after vaporization of the fire retardant can circulate.

7. The power storage device according to claim 5 or 6, wherein the cooling section has an internal pressure relief valve that releases the internal pressure when the internal pressure of the cooling section exceeds a predetermined pressure.

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