JP7159542B2 - power storage device - Google Patents

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 the self-heating temperature or higher, the adjacent storage element also heats up due to self-heating and further heats the adjacent storage element, resulting in a chain reaction. 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. can cause overheating.

Patent Literature 1 discloses a technique for suppressing conduction of heat from a power storage element to an adjacent power storage element.

When the electric storage element is a non-aqueous electrolyte secondary battery, a widely known non-aqueous electrolyte is one in which an electrolyte such as lithium hexafluorophosphate (LiPF ₆ ) is dissolved in a non-aqueous solvent containing ethylene carbonate as a main component. It is These non-aqueous solvents are generally volatile and flammable. Therefore, it is required to suppress ignition in the power storage device.
Patent Document 2 discloses that the non-aqueous electrolyte contains a non-cyclic fluorinated ether containing at least one —CF ₂ H group at the terminal, a cyclic carbonate compound having a carbon-carbon π bond, and a sultone, It is disclosed to render the water electrolyte flame retardant.
In Patent Document 3, the non-aqueous electrolyte contains a fluorinated phosphate ester and/or a fluorinated linear carbonate having a side chain with 3 or less carbon atoms, and the ratio of these non-aqueous electrolytes to the solvent is 15. It is disclosed to make the non-aqueous electrolyte flame-retardant by setting the amount to 30% by mass.

JP 2015-195149 A Japanese Patent No. 5092416 Japanese Patent No. 5842873

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.
For the purpose of preventing ignition of power storage devices, in order for the non-aqueous electrolyte of the non-aqueous electrolyte secondary battery to exhibit sufficient flame retardancy, it is necessary to mix a large amount of fluorinated carbonate, etc., but good battery characteristics There is a limit to the amount of fluorinated carbonate or the like added in order to obtain

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

A power storage device according to the present invention includes a plurality of power storage elements, and a cooling unit disposed at least between the power storage elements, containing a flame retardant, and cooling the power storage elements by the heat of vaporization of the flame retardant. It is characterized by having

According to the present invention, in the cooling portion that contacts the heated storage element, the built-in flame retardant absorbs heat from the storage element and evaporates, thereby cooling the storage element well. Since the cooling part is arranged at least between the storage elements, the conduction of heat to the storage elements adjacent to the storage element that has generated heat is suppressed. Therefore, chain heat transfer between the storage elements is prevented.
Since the flame retardant is contained in the cooling part, after being vaporized, it is liquefied in the cooling part and reused for cooling the electric storage element, whereby the electric storage element is efficiently cooled.
When the flame retardant is vaporized and released from the cooling unit, and the flammable component is released from the power storage element, the flammable component is rendered flame-retardant by the flame retardant, and ignition is prevented or suppressed in the power storage device. be.

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. Fig. 3 is a perspective view of a cooling module; FIG. 4 is a cross-sectional view taken along line IV-IV of FIG. 3; FIG. 4 is an explanatory diagram illustrating cooling by a cooling module when an electric storage element generates heat; It is an explanatory view explaining suppression of ignition by a flame retardant. FIG. 5 is a perspective view of a cooling module according to a second embodiment; It is explanatory drawing when internal space is connected in 2nd Embodiment. It is an explanatory view explaining suppression of ignition by a flame retardant. FIG. 11 is a perspective view of a cooling module according to a third embodiment; FIG. 11 is a perspective view of a power storage device according to a fourth embodiment;

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 the storage element 1. FIG. 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). Alternatively, the case may be a pouch case using a laminated sheet.

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 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 little swelling (swelling of the outer packaging such as a metal case such as the case 11 and a pouch case) due to charge-discharge cycles. Since swelling of the exterior body due to charge/discharge cycles is small, pressing of the exterior body against the cooling section 31 during normal use is suppressed.

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 , Li ₂ MSiO ₄ , and LiMBO ₃ (M is one or more transition metal elements selected from Fe, Ni, Mn, Co, etc.), titanium 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 (SiO, etc.), lithium metal oxide substances (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 module 30. As shown in FIG.
The power storage device 100 includes a plurality of power storage elements 1 , a cooling module 30 that cools the power storage elements 1 , and a case 40 that houses the power storage elements 1 and the cooling module 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 element 1, the cooling module 30, and the like 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 module 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 module 30 includes a plate-like cooling portion 31 , connecting portions 32 and 33 connecting the cooling portions 31 , and an internal pressure release valve 34 . The two cooling portions 31 are interposed between the long side surfaces of the adjacent storage elements 1, and the other two cooling 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 at the center of the upper surface of each cooling section 31 .
The cooling units 31 may be provided corresponding to the number of the storage elements 1, or may be provided between the storage elements 1 and may be provided so as to abut on the outer long side surfaces of the storage elements 1 at both ends. .
The installation position of the internal pressure release valve 34 is also not limited to the central portion of the upper surface of the cooling portion 31 .
The internal pressure release valve 34 can be installed at a position where ignition can be effectively prevented when the flame retardant L, which will be described later, is ejected. As shown in FIG. 2, the rupture valve 20 of the storage element 1 and the internal pressure release valve 34 of the cooling section 31 may face in the same direction. The internal pressure release valve 34 may face upward in the direction of gravity.

The cooling part 31 is hollow.
A flame retardant L is accommodated in the cooling part 31 .
The upper ends of the long sides of adjacent cooling units 31 are connected by a connecting portion 32 . The connection part 32 is hollow, and is configured so that the gas in the connected cooling part 31 flows through the connection part 32 .
The lower ends of the long sides of adjacent cooling units 31 are connected by a connecting portion 33 . The connection part 33 is hollow, and is configured so that the flame retardant L in the connected cooling part 31 flows through the connection part 33 .
That is, the internal spaces of the cooling portion 31, the connecting portion 32, and the connecting portion 33 communicate with each other.

Note that the outer cooling part 31 can be omitted. For example, when the number of electric storage elements 1 is five, four cooling units 31 are arranged between the electric storage elements 1 and the four cooling units 31 are connected by connecting portions 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 cooling portion 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 so as to be stamped with a mold having projections.

The flame retardant L evaporates to exhibit flame retardancy against flammable gases. The flame retardant L preferably has a large heat of vaporization, has corrosion resistance, and does not generate toxic gas.
The flame retardant L preferably contains at least one of an acyclic fluorinated ether, a fluorinated phosphate, and a phosphazene derivative. These vaporize and have high flame retardancy.

The non-cyclic fluorinated ether is more preferably represented by the following formula (1).
CX3 _- jHj-(CFxH2 _{-x ) m} -O-( _{CFyH2 -y ) n} -CF3 _{- kHk} (1)
(where X is F or CF ₃ , j, k, m, n, x, and y are integers, 0≦j≦3, 0≦k≦3, 1≦m≦3, 0≦n≦1, 0≤x≤2, 0≤y≤2, and contains at least one fluorine atom.)
_{Specifically , for example , HCF2CF2CH2OCF2CF2H , HCF2CF2OCH2CF3 , CF3CF2CH2OCF2CF2H , HCF2CF2CH2OCHF2 , CF _ _ _ _ 3} CF ₂ CH ₂ OCF ₂ H, (CF ₃ ) ₂ CHCF ₂ OCF ₂ H, CF ₃ CHFCF ₂ CH ₂ OCHF ₂ and the like can be used alone or in mixtures of two or more thereof, but are limited to these. not something.

The fluorinated phosphate is more preferably represented by the following formula (2).

(where j, k, l, m, n, o, x, y, z are integers, 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 contains at least one fluorine atom.)

The phosphazene derivative is more preferably represented by the following formula (3).

(Wherein, R ₁ to R ₆ are identical or non-identical hydrogen atoms, halogen atoms, linear or branched alkyl groups having 1 to 10 carbon atoms, alkyl groups having 1 to 10 carbon atoms substituted with fluorine atoms, An alkoxy group having 1 to 10 carbon atoms and an alkoxy group having 1 to 10 carbon atoms substituted with a fluorine atom.)

The phosphazene derivative is further a fluorine-containing phosphazene derivative, wherein at least one of R ₁ to R ₆ is a fluorine atom, an alkyl group substituted with a fluorine atom, or an alkoxy group substituted with a fluorine atom. preferable.

Among the fluorine-containing phosphazene derivatives, monoethoxypentafluorocyclotriphosphazene represented by Chemical Formula 3 below and monophenoxypentafluorocyclotriphosphazene represented by Chemical Formula 4 below are particularly preferred.

The storage amount of the flame retardant L is based on the internal volume of the cooling portion 31 and the connecting portions 32 and 33, the assumed heat generation temperature of the power storage element 1, the volume when the flame retardant L is vaporized, etc. The cooling unit 31 is set so as not to be damaged.

FIG. 5 is an explanatory diagram illustrating cooling by the cooling module 30 when the power storage element 1 generates heat.
It is assumed that the cooling module 30 contains the flame retardant L, and the central power storage element 1 generates heat.
Heat is conducted from the heated storage element 1 to the cooling portions 31, 31 on both sides, and the flame retardant L in the cooling portion 31 evaporates (FIG. 5A). When the flame retardant L evaporates, the heat of vaporization is removed, and the storage element 1 is rapidly cooled by an endothermic reaction. The liquid amount of the flame retardant L in the cooling part 31 is reduced.

The gas in the cooling section 31 flows upward by thermal convection, passes through the connecting sections 32, 32, and moves to the outer cooling section 31 having a lower temperature (FIG. 5B). The gas condenses in the outer cooling section 31, and the liquid amount of the flame retardant L in the outer cooling section 31 increases.

The flame retardant L increases in the outer cooling portion 31 and flows to the inner cooling portion 31 via the connecting portion 33, and the liquid amount of the flame retardant L in the four cooling portions 31 becomes equal (Fig. 5C). The circulated flame retardant L also absorbs the heat generated by the storage element 1, vaporizes, and circulates in the same manner as described above.

FIG. 6 is an explanatory diagram illustrating suppression of ignition by a flame retardant.
When thermal runaway in which the temperature of the storage element 1 rises sharply occurs, the amount of heat absorbed from the storage element 1 increases, and the amount of evaporation of the flame retardant L increases. When the internal pressure of the cooling portion 31 in contact with the storage element 1 reaches a predetermined value or more, the internal pressure release valve 34 of the cooling portion 31 is opened to release the vaporized flame retardant L to the outside. FIG. 6 shows a state in which the internal pressure release valves 34 of the cooling units 31 on both sides of the storage element 1 are opened and the flame retardant L is released. When the internal pressure of the outer cooling portion 31 also reaches a predetermined value or higher, the internal pressure release valve 34 is opened.
When the internal pressure of the electric storage element 1 reaches a predetermined value or more, the burst valve 20 is opened and the flammable component of the volatilized electrolyte is released to the outside. The flammable component is rendered flame retardant by the flame retardant L to prevent ignition.

As described above, the power storage device 100 of the present embodiment is arranged between a plurality of power storage elements 1 and at least between the power storage elements 1, incorporates the flame retardant L, and the heat of vaporization of the flame retardant L and a cooling unit 31 that cools the storage element 1 .

According to the above configuration, when the flame retardant L in the cooling portion 31 in contact with the heat-generating storage element 1 evaporates, it absorbs the heat of vaporization, so the storage element 1 is cooled well. Since the cooling part 31 is arranged at least between the storage elements 1, the conduction of heat to the storage elements 1 adjacent to the storage element 1 that has generated heat is suppressed. Even when the heat is transferred to the adjacent power storage element 1 without passing through the cooling part 31 , the long side facing the heat-generated power storage element 1 is cooled by the cooling part 31 . Therefore, chain transfer of heat to the storage element 1 is suppressed.
The cooling structure of the cooling module 30 is simple, and can cool the electric storage element 1 even when a low degree of heat generation occurs.
Since the flame retardant L is contained in the cooling unit 31, after being vaporized, it is liquefied in the cooling unit 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 flame retardant L evaporates to exhibit flame retardancy against flammable gas.

According to the above configuration, when the flame retardant L absorbs heat from the heat storage element 1, vaporizes, and is released from the internal pressure release valve 34, it mixes with the flammable component released from the storage element 1 and becomes flammable. The component is rendered flame-retardant, and ignition is prevented in power storage device 100 .

In the power storage device 100 described above, the flame retardant L includes at least one of an acyclic fluorinated ether, a fluorinated phosphate, and a phosphazene derivative.

According to the above configuration, the flame retardant L has high flame retardancy by being vaporized.

In the power storage device 100 described above, the cooling module 30 has a connecting portion that connects the plurality of cooling units 31 so that the internal spaces communicate with each other.

According to the above configuration, the gas generated by vaporizing the flame retardant L in one cooling portion 31 that contacts the heated storage element 1 passes through the connecting portions 32 and 33 due to thermal convection, It flows to the cooling part 31 . The gas is liquefied in the other cooling section 31, flows to the one cooling section 31, and the flame retardant L is circulated.
Therefore, the flame retardant L is reused for cooling the storage element 1, and the storage element 1 is efficiently cooled.
In addition, the heated gas flows from one cooling portion 31 to the other cooling portion 31 via the connecting portions 32 and 33, so that the long side surface in contact with one cooling portion 31 and the other , the temperature difference between the long side surfaces contacting the cooling portion 31 is reduced, and the temperature difference between the storage elements 1 is reduced. By circulating the gas and the flame retardant L, 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, cooling unit 31 satisfactorily dissipates heat from power storage elements 1 and reduces the temperature difference between power storage elements 1 .

In the power storage device 100 described above, the cooling unit 31 has an internal pressure release valve 34 that releases the internal pressure when the internal pressure of the cooling unit 31 exceeds a predetermined pressure.

According to the above configuration, when the amount of evaporation of the flame retardant L is large and the internal pressure of the cooling section 31 exceeds a predetermined pressure, the internal pressure release valve 34 is opened and the gas is released to the outside. It is possible to prevent the energy storage device 1 from being pressed due to swelling of the cooling portion 31 due to the release of the gas.
When the temperature of the storage element 1 rises sharply, the amount of heat absorbed from the storage element 1 increases, and the amount of evaporation of the flame retardant L increases. When the internal pressure reaches a predetermined value or higher, the cooling portion 31 opens, thereby releasing the vaporized flame retardant L to the outside. When the internal pressure of the storage element 1 reaches a predetermined value or higher, the storage element 1 opens and the flammable component of the volatilized electrolyte is released to the outside. The flammable component is rendered flame retardant by the flame retardant L to prevent ignition.

Even when the energy storage element 1 at the end rather than the center generates heat, the heat is absorbed by the cooling 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 module 30 is not limited to the structure of FIG. Connecting portions may be provided such that rectangular tubes pass through the upper and lower portions of each of the ends of the four cooling portions 31 in the longitudinal direction.

(Second embodiment)
FIG. 7 is a perspective view of the cooling module 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 module 35 comprises four cooling units 31 and a cooling plate 36 .
Unlike the first embodiment in which the four cooling units 31 are connected by connecting portions 32 and 33 , the cooling module 35 has the end surfaces 31 a of the four cooling units 31 in contact with the cooling plate 36 . The cooling part 31 contains the flame retardant L as in the first embodiment.
The cooling part 31 and the cooling plate 36 may or may not communicate with each other in internal space.

FIG. 8 is an explanatory diagram of the case where the internal spaces are communicated in this embodiment. The storage element 1 is inserted between the cooling portions 31 , and the flame retardant L is accommodated in the cooling portions 31 and the cooling plate 36 .
When the central storage element 1 generates heat, as in the first embodiment, the flame retardant L in the cooling portion 31 in contact with the storage element 1 takes heat of vaporization from the storage element 1 and evaporates. is quenched. The liquid amount of the flame retardant L in the cooling section 31 is reduced. The generated gas flows through the cooling plate 36 to another cooling portion 31, and the flame retardant L produced by condensation flows to the cooling portion 31 where the amount of the flame retardant L is reduced. The flame retardant L also absorbs heat to cool the storage element 1, and the resulting gas 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 flame retardant L in the cooling portion 31 in contact with the storage element 1 takes heat of vaporization from the storage element 1 and evaporates. quenched. The generated gas is cooled by the cooling plate 36 and condensed into the flame retardant L. The flame retardant L absorbs heat from the storage element 1 and vaporizes, cooling the storage element 1 .

Also in the present embodiment, the cooling module 35 having a simple structure suppresses the conduction of heat to the adjacent storage element 1 to the storage element 1 that generates heat. Suppressed.

FIG. 9 is an explanatory diagram illustrating suppression of ignition by the flame retardant L. FIG.
When thermal runaway in which the temperature of the storage element 1 rises sharply occurs, the amount of heat absorbed from the storage element 1 increases, and the amount of evaporation of the flame retardant L increases. When the internal pressure of the cooling portion 31 in contact with the power storage element 1 reaches a predetermined value or higher, the internal pressure release valve 34 is opened to release the vaporized flame retardant L to the outside. When the internal pressure of the electric storage element 1 reaches a predetermined value or more, the burst valve 20 is opened and the flammable component of the volatilized electrolyte is released to the outside.
The flammable component is rendered flame retardant by the flame retardant L to prevent ignition.

In the power storage device of this embodiment, each of the power storage elements 1 is formed in a rectangular parallelepiped shape, and the cooling part 31 of each of the power storage elements 1 is in contact with a surface different from the facing long side surface, so that the plurality of power storage elements 1 are in contact with each other. is provided with a cooling plate 36 for cooling, and heat can be conducted between the cooling plate 36 and the cooling portion 31 .

According to the above configuration, heat is conducted between the cooling plate 36 and the cooling section 31, so that the heat is radiated well. The gas generated by vaporization of the flame retardant L is cooled and liquefied, and the flame retardant L absorbs heat from the storage element 1 again to cool the storage element 1 .

In the power storage device described above, the cooling plate 36 and the cooling section 31 are integrated so that the flame retardant L or the vaporized gas of the flame retardant L can circulate.

According to the above configuration, in one cooling portion 31 in contact with the heat-generating power storage element 1, the gas generated by evaporating the flame retardant L passes through the cooling plate due to thermal convection, and flows into the other cooling portion 31. flow to The gas is liquefied in the other cooling section 31, flows to the one cooling section 31, and the flame retardant L is circulated.
Therefore, the flame retardant L 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 the flame retardant L, 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, cooling unit 31 satisfactorily dissipates heat from power storage elements 1 and reduces the temperature difference between power storage elements 1 .

(Third embodiment)
FIG. 10 is a perspective view of the cooling module 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 module 37 of the third embodiment has a configuration in which the bottom surfaces 31b of the four cooling portions 31 of the cooling module 30 of the first embodiment are in contact with the cooling plate 38. As shown in FIG. The cooling part 31 contains a flame retardant L (not shown) as in the first embodiment.
The internal spaces of the cooling part 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 power storage element 1 generates heat, the flame retardant L in the cooling portion 31 in contact with the power storage element 1 evaporates, and the power storage element 1 is cooled by the heat of vaporization when it evaporates, as in the first embodiment. be done. The generated gas flows through the other cooling section 31, and the flame retardant L produced by condensation flows into the cooling section 31 where the amount of the flame retardant L is small. Cooling plate 38 cools the bottom surface of storage element 1 and cools cooling portion 31 . The flame retardant L in the cooling portion 31 in contact with the storage element 1 also absorbs heat from the storage element 1 and evaporates, thereby cooling the storage element 1 .

In the present embodiment, as in the first and second embodiments, the cooling module 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.

When the temperature of the storage element 1 rises sharply, the amount of heat absorbed from the storage element 1 increases, and the amount of evaporation of the flame retardant L increases. When the internal pressure reaches a predetermined value or higher, the internal pressure release valve 34 is opened to release the vaporized flame retardant L to the outside. When the internal pressure of the electric storage element 1 reaches a predetermined value or more, the burst valve 20 is opened and the flammable component of the volatilized electrolyte is released to the outside.
The flammable component is rendered flame retardant by the flame retardant L to prevent ignition.

(Fourth embodiment)
FIG. 11 is a perspective view of a power storage device 101 according to the fourth embodiment. In the figure, the same parts as those in FIG. 2 are denoted by the same reference numerals, and detailed description thereof will be omitted.
Unlike the power storage device 100 according to the first embodiment, the power storage device 101 does not have connecting portions 32 and 33 that connect the cooling portion 31 . The cooling part 31 is arranged independently between the storage elements 1 or between the storage elements 1 and the inner surface of the case 40 . The cooling part 31 contains a flame retardant L (not shown).

When the storage element 1 generates heat, the flame retardant L in the cooling portion 31 in contact with the storage element 1 takes the heat of vaporization from the storage element 1 and evaporates, thereby rapidly cooling the storage element 1 . The generated gas convects, is cooled by the outside of power storage device 101 and/or the outside air, and is condensed into flame retardant L. The flame retardant L absorbs heat from the storage element 1 and vaporizes, cooling the storage element 1 .

In the present embodiment, since the cooling units 31 are interposed between the storage elements 1, the storage elements 1 that generate heat are cooled by the cooling units 31 on both sides, and the heat is transferred to the adjacent storage elements 1, as in the first embodiment. Heat is suppressed. Even when the heat is transferred to the adjacent power storage element 1 without passing through the cooling part 31 , the long side facing the heat-generated power storage element 1 is cooled by the cooling part 31 . Therefore, chain transfer of heat to adjacent storage elements 1 is suppressed.

When the temperature of the storage element 1 rises sharply, the amount of heat absorbed from the storage element 1 increases, and the amount of evaporation of the flame retardant L increases. When the internal pressure reaches a predetermined value or higher, the internal pressure release valve 34 is opened to release the vaporized flame retardant L to the outside. When the internal pressure of the electric storage element 1 reaches a predetermined value or more, the burst valve 20 is opened and the flammable component of the volatilized electrolyte is released to the outside.
The flammable component is rendered flame retardant by the flame retardant L to prevent ignition.

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 fourth embodiments, the case where the positive electrode terminal 4 and the negative electrode terminal 8 of the storage element 1 are arranged facing upward is described, but the present invention is not limited to this. Even when the positive terminal 4 and the negative terminal 8 are arranged to face sideways, the cooling structure of the present invention can be applied.
Moreover, although the case where the storage element 1 is a lithium ion secondary battery has been described, 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 power 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 cooling module 31 cooling section 32, 33 connecting section 34 internal pressure release valve 36, 38 cooling plate 40 case 100, 101 power storage device

Claims (6)

a plurality of power storage elements;
a cooling unit disposed at least between the power storage elements, containing a flame retardant, and cooling the power storage elements by the heat of vaporization of the flame retardant;
a gas generated by vaporization of the flame retardant contained in the cooling unit is liquefied in the cooling unit, and the heat of vaporization of the liquefied flame retardant cools the power storage element;
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,
The power storage device, wherein the internal pressure release valve is arranged in the cooling section so as to face in the same direction as a burst valve provided in the power storage element . The power storage device according to claim 1, wherein the flame retardant exhibits flame retardancy by being vaporized. 3. The power storage device according to claim 2, wherein the flame retardant includes at least one of acyclic fluorinated ether, fluorinated phosphate, and phosphazene derivative. 4. The power storage device according to any one of claims 1 to 3, further comprising a connecting portion that connects a plurality of cooling portions so that the internal spaces communicate with each other. each of the storage elements is formed in a rectangular parallelepiped shape,
a cooling plate that cools the plurality of power storage elements by contacting a surface different from the long side surface facing the cooling part of each of the power storage elements,
5. The power storage device according to any one of claims 1 to 4, wherein heat can be conducted between said cooling plate and said cooling portion. 6. The power storage device according to claim 5, wherein the cooling plate and the cooling unit are integrated so that the flame retardant or gas obtained by vaporizing the flame retardant can circulate.

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