Electricity storage device container

Abstract

To provide a container for a power storage device capable of reducing the risk of fire spreading to the outside of the container at the time of abnormality such as breakage of the power storage device or a high temperature environment.SOLUTION: The container for a power storage device includes a container body for a power storage device that accommodates the power storage device, and a mesh-like bag or basket that accommodates foamed particles of a thermally depolymerizable polymer disposed in a gap between the container body for a power storage device and the power storage device.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to containers for electricity storage devices, such as transport containers for packaging and transporting electricity storage devices such as lithium ion batteries, lithium ion capacitors, and electric double layer capacitors, or storage containers for packaging and storing these electricity storage devices, and in particular to containers for electricity storage devices that can reduce the risk of fire spreading outside the container even if the electricity storage device catches fire in an abnormal situation such as when it is damaged or in a high-temperature environment. [Background technology]

[0002] In recent years, electricity storage devices such as secondary batteries, lithium ion capacitors, and electric double layer capacitors, each of which has an electricity storage device using a non-aqueous electrolyte housed in a casing, have been used as power sources for high-output portable devices, electric vehicles, and the like.

[0003] Such energy storage devices typically have a set upper voltage limit, and are controlled to not exceed the upper voltage limit by combining them with an appropriate protection circuit. However, if the protection circuit malfunctions and the upper voltage limit is exceeded, if charging and discharging are repeated, or if a short circuit occurs due to an external factor, the energy storage device falls into an overcharged state, and the electrolyte reacts with the electrode material, etc., generating gas, which increases the internal pressure. This generated gas may contain flammable gases such as the electrolyte, methane, carbon monoxide, ethylene, ethane, and propane, and may pose a risk of fire or explosion if released outside the energy storage device.

[0004] In recent years, there has been a demand for higher output and larger capacity in electricity storage devices such as lithium-ion capacitors and electric double-layer capacitors, and opportunities to use large currents are increasing for individual electricity storage devices or modules in which multiple electricity storage devices are stacked. For example, in a module in which multiple electricity storage devices are stacked, if one electricity storage device falls into an overcharged state, even after gas is released together with the electrolyte, the other electricity storage devices may continue to function and continue to flow a large current. This may result in severe overheating due to a short circuit, increasing the risk of fire or explosion as described above.

[0005] As a technique for preventing ignition of such electricity storage devices, for example, a method has been proposed in which gas generated inside a lithium ion battery is absorbed by a flammable gas absorbent material to prevent the battery from exploding (Patent Documents 1 and 2).

[0006] Meanwhile, a method has been proposed in which a fire extinguishing agent is placed inside a lithium-ion battery to lower the temperature of the gas released to the outside when the safety valve opens due to an increase in internal pressure caused by gas generation inside the battery (Patent Document 3).Furthermore, a method has been proposed in which a porous material having a non-flammable gas, an aqueous solvent, or a non-flammable solvent adsorbed within and on the surface of the pores is placed inside the lithium-ion battery to prevent fires caused by gas generated from the lithium-ion battery (Patent Document 4). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-155790 [Patent Document 2] Japanese Patent Application Laid-Open No. 2003-077549 [Patent Document 3] Japanese Patent Application Laid-Open No. 2010-287488 [Patent Document 4] Japanese Patent Application Laid-Open No. 2013-187089 Summary of the Invention [Problem to be solved by the invention]

[0008] However, because a large amount of gas is instantaneously generated during an electrical abnormality or thermal runaway, the method of disposing a gas adsorbent in an electricity storage device as described in Patent Documents 1 and 2 has the problem that the gas adsorption amount and gas adsorption speed are insufficient for the limited space of an electricity storage device, and gas emission from the electricity storage device cannot be completely suppressed. Also, as described in Patent Documents 3 and 4, the method of disposing a fire extinguishing agent or a material that adsorbs non-flammable gas or an aqueous solvent or non-flammable solvent in the pores and surface of a porous material in an electricity storage device to lower the temperature inside the lithium-ion battery has the problem that if the gas adsorption amount is insufficient, the effect is not fully exerted and gas emission cannot be completely suppressed.

[0009] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a container for an electricity storage device that can reduce the risk of fire spreading to the outside of the container in the event of an abnormality such as damage to the electricity storage device or a high-temperature environment. [Means for solving the problem]

[0010] In order to solve the above problems, the present invention provides a container for an electricity storage device, in which foamed particles of a thermally depolymerizable polymer are disposed in a gap between the electricity storage device and a container body that houses the electricity storage device (Invention 1). In particular, in the above invention (Invention 1), it is preferable that the electricity storage device uses a non-aqueous electrolyte (Invention 2).

[0011] According to these inventions (Inventions 1 and 2), by placing foamed particles of a thermally depolymerizable polymer in the gap between the electricity storage device and the container for the electricity storage device, the risk of fire spreading to the outside of the container for the electricity storage device in the event of an abnormality such as damage to the electricity storage device or a high-temperature environment can be reduced.

[0012] In the above invention (Invention 1), it is preferable that the expanded particles of the thermally depolymerizable polymer contain 10% by weight or more of the thermally depolymerizable polymer as a whole (Invention 3).

[0013] According to this invention (Invention 3), it is possible to preferably exert the effect of preventing the spread of fire to the outside of the container when an abnormality occurs in the electricity storage device.

[0014] In the above invention (Invention 1), it is preferable that the expanded particles of the thermally depolymerizable polymer are expanded particles of a polymer (homopolymer or copolymer of two or more components) using one or more of methyl methacrylate (MMA), α-methylstyrene (AMS), and tetrafluoroethylene (TFE) as monomer components (Invention 4).

[0015] According to this invention (Invention 4), it is possible to suitably reduce the risk of fire spreading to the outside of the transport container in the event of an abnormality such as damage to the electricity storage device or a high temperature environment.

[0016] In the above invention (Invention 1), it is preferable that the expanded particles of the thermally depolymerizable polymer are in the shape of beads or spheres (Invention 5).

[0017] According to this invention (Invention 5), by making the expanded particles of the thermally depolymerizable polymer bead-shaped or spherical, they can be inserted directly into gaps in a container, or placed in a mesh bag or container that is breathable but does not allow the bead-shaped or spherical expanded particles of the thermally depolymerizable polymer to pass through, and then placed above and below the container for the electricity storage device as shock-absorbing or cushioning material, thereby providing a wide variety of installation options and making the product easy to handle.

[0018] In the above invention (Invention 5), the bead-shaped or spherical expanded beads preferably have a particle size of 0.5 mm to 20 mm (Invention 6).Furthermore, the bead-shaped or spherical expanded beads are preferably contained in a mesh bag or cage, and the mesh diameter is preferably 0.3 mm to 7 mm, which is smaller than the minimum particle size of the bead-shaped or spherical expanded beads (Invention 7).

[0019] According to these inventions (Inventions 6 and 7), by disposing foamed particles of thermally depolymerizable polymer in the gap between the container and the electricity storage device, it is possible to prevent the spread of fire outside the container in the event of an abnormality in the electricity storage device. In this case, by storing the foamed particles of thermally depolymerizable polymer in a bead- or spherical shape in a mesh bag or cage that is breathable but impermeable to the foamed particles, gases and ejected material that escape in the event of an abnormality in the electricity storage device pass through the mesh bag or cage, thereby coming into contact with the thermally depolymerizable polymer multiple times. Furthermore, the filtering effect of the foamed particles as they pass through the bead- or spherical particles reduces the amount of ejected material that escapes outside the transport container, thereby efficiently and significantly reducing the risk of fire. Furthermore, by disposing the foamed particles above and below the electricity storage device during transport as buffer or cushioning material, the device can be made easier to handle. In particular, by making the particle size of the bead-shaped or spherical expanded particles of the thermally depolymerizable polymer 0.5 mm to 20 mm and the mesh diameter of the mesh bag or cage 0.3 mm to 7 mm, which is smaller than the minimum particle size of the bead-shaped or spherical expanded particles of the thermally depolymerizable polymer, the bead-shaped or spherical expanded particles of the thermally depolymerizable polymer will not leak out of the mesh bag or cage.

[0020] In the above invention (Invention 6), the density of the bead-shaped or spherical expanded particles is preferably 18 g / L to 20 g / L (Invention 8).

[0021] According to this invention (Invention 8), by disposing bead-shaped or spherical expanded particles of a predetermined density in the gap between the electricity storage device and the casing, it is possible to effectively prevent the fire from spreading to the outside in the event of a fire occurring inside the electricity storage device. Note that in this specification, the density of the expanded particles is the bulk density.

[0022] In the above inventions (Inventions 1 to 8), a plurality of the electricity storage devices may be stacked (Invention 9).

[0023] In the above invention (Invention 9), in an electricity storage device stack in which multiple electricity storage devices are stacked, if there is an abnormality in one electricity storage device, even if flammable gas is ejected from the electricity storage device and flows into the space of the container, the material of the foamed particles of the thermally depolymerizable polymer affects the flammable gas, thereby significantly reducing the risk of the fire spreading outside the container, and therefore the invention is particularly suitable for application to electricity storage device stacks. [Effects of the Invention]

[0024] The container for an electricity storage device of the present invention has foamed particles of a thermally depolymerizable polymer disposed in the gap between the electricity storage device and the container body. This allows the thermally depolymerizable polymer to affect high-temperature ejected material and gas emitted from the electricity storage device due to a short circuit or the like of the electricity storage device, thereby significantly reducing the risk of the container for an electricity storage device catching fire. DETAILED DESCRIPTION OF THE INVENTION

[0025] The container for an electricity storage device of the present invention will be described in detail based on the following embodiments.

[0026] [Containers for electricity storage devices] The container for an electricity storage device of this embodiment has a structure in which expanded particles of a thermally depolymerizable polymer are arranged in a gap between the container body and a region in which the electricity storage device is housed in the container body.

[0027] (Electricity storage device) In this embodiment, the power storage device is not particularly limited, and either a primary battery or a secondary battery can be used, but a secondary battery is preferred. The type of secondary battery is not particularly limited, and examples that can be used include lithium ion batteries, lithium ion polymer batteries, all-solid-state batteries, lead acid batteries, nickel-metal hydride batteries, nickel-cadmium batteries, nickel-iron batteries, nickel-zinc batteries, silver oxide-zinc batteries, metal-air batteries, polyvalent cation batteries, condensers, and capacitors. Among these, those using nonaqueous electrolytes are preferably used. Among these secondary batteries, lithium ion batteries, lithium ion polymer batteries, lithium ion capacitors, all-solid-state batteries, and the like are suitable applications of the battery material of the present invention.

[0028] The nonaqueous electrolyte may be, for example, a mixed solution of a cyclic carbonate such as propylene carbonate (PC) or ethylene carbonate (EC) with a chain carbonate such as dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), or diethyl carbonate (DEC). Furthermore, the nonaqueous electrolyte may contain a lithium salt such as lithium hexafluorophosphate dissolved therein, if necessary. For example, a mixed solution obtained by mixing ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) in a 1:1:1 ratio, or a mixed solution obtained by mixing propylene carbonate (PC), ethylene carbonate (EC), and diethyl carbonate (DEC) in a 1:1:1 ratio to which 1 mol / L of lithium hexafluorophosphate has been added, may be used.

[0029] (Container body for electricity storage device) In this embodiment, the container body is not particularly limited as long as it can encase the above-described electricity storage device (electricity storage device stack) with a gap therebetween, and various materials such as cardboard, synthetic resin, and metal can be used. This container body is generally shaped like a rectangular box, but is not limited to this. This container body is preferably provided with a release valve or release hole so that ejected gas or ejected material from the electricity storage device can be released to the outside of the container in the event of an abnormality in the electricity storage device.

[0030] (fire-preventive material) In this embodiment, foamed particles of a thermally depolymerizable polymer are disposed as an ignition prevention material in the gap between the electricity storage device and the container body.

[0031] (thermally depolymerizable polymer) In this embodiment, a thermally depolymerizable polymer refers to a polymer that has the depolymerization property of decomposing a polymer into monomers by heat or light and leaves no residue when heated. Examples of the thermally depolymerizable polymer include those based on a polymer (homopolymer or polymer of two or more components) using one or more of methyl methacrylate (MMA), α-methylstyrene (AMS), and tetrafluoroethylene (TFE) as monomer components. Among these, a polymer using methyl methacrylate (MMA) and α-methylstyrene (AMS) as monomer components is preferred. Alternatively, a polymer composed of methyl methacrylate (MMA):α-methylstyrene (AMS) in a molar ratio of 5:95 to 95:5 may also be used. Furthermore, a polymer obtained by blending other monomer components (such as styrene) during polymerization may also be used. Such thermally depolymerizable polymers can significantly reduce the risk of fire in containers for electricity storage devices, due to a mechanism in which they undergo thermal decomposition to generate monomers due to high-temperature ejections and gases emitted from the electricity storage device due to a short circuit or other reasons.

[0032] (Foamed particles of thermally depolymerizable polymer) In this embodiment, the expanded particles of the thermally depolymerizable polymer can be produced using one or more of methyl methacrylate (MMA), α-methylstyrene (AMS), and tetrafluoroethylene (TFE) as monomer components by a known method (for example, the method described in JP 2007-314774 A).

[0033] The expanded particles of the thermally depolymerizable polymer may contain any suitable additives as needed, such as a crosslinking agent, a tackifier, a plasticizer (e.g., a trimellitic ester-based plasticizer, a pyromellitic ester-based plasticizer, etc.), a pigment, a dye, a filler, an antioxidant, a conductive material, an antistatic agent, an ultraviolet absorber, a light stabilizer, a release agent, a softener, a surfactant, a flame retardant, and an antioxidant.

[0034] It is also possible to add known fire extinguishing agents to the foamed particles, and further, it is also possible to use known fire extinguishing agents by dispersing them among the foamed particles.

[0035] In this embodiment, there are no particular restrictions on the shape of the expanded beads of the fire-preventing material placed in the gap between the electricity storage device and the container, but considering ease of handling when placing them in the gap between the electricity storage device and the container, they are preferably bead-shaped or spherical. These bead-shaped or spherical expanded beads preferably have an average particle size of 0.5 mm to 20 mm, and particularly preferably an average particle size of 1 mm to 10 mm. If the average particle size is less than 0.5 mm, the bead-shaped or spherical expanded beads are not easy to handle, while if it exceeds 20 mm, they may not be able to fully reduce the risk of fire in the electricity storage device, which is undesirable.

[0036] The density of such bead-like or spherical expanded particles is preferably 18 g / L to 20 g / L.

[0037] These bead-shaped or spherical expanded particles are then housed in a mesh bag or cage and used as a fire prevention element. The mesh diameter of the mesh bag or cage may be any size smaller than the particle size of the bead-shaped or spherical expanded particles of the thermally depolymerizable polymer so that they do not pass through. However, it is preferable that the mesh diameter is smaller than the minimum particle size (-20% of the median) of the pellet-shaped or bead-shaped expanded particles containing the acrylic polymer, and is 0.3 mm to 7 mm, particularly 0.5 mm to 2 mm. The mesh bag or cage that houses the bead-shaped or spherical expanded particles is preferably soft or flexible, but may also be rigid. Materials such as synthetic resin, elastomer, and metal can be used, but flexible bags made of synthetic resin are preferred. In the case of a rigid cage, it should be smaller than the main body of the electricity storage device transport container.

[0038] These ignition prevention materials can also be used by adding materials that have a cooling effect through heat transfer and absorption against ejected materials and gases from the electricity storage device, an effect of suppressing combustion radical reactions, and an extinguishing effect that makes flames on the surface of the adsorbent unstable.

[0039] The above-mentioned fire prevention materials may be used alone or in combination of two or more materials.

[0040] [How to use the container for the electricity storage device] The above-described energy storage device container may be transported or stored after foam particles made of an anti-ignition material have been placed in the container body in advance, and then an energy storage device with a state of charge (SOC) of, for example, about 30% is placed inside the container and the container is sealed; alternatively, an energy storage device may be placed in the container body, and then foam particles made of an anti-ignition material may be placed in the gap, and the container may be sealed before transport or storage.

[0041] By storing or transporting an electricity storage device in a container of this embodiment, even if the electricity storage device were to ignite due to a short circuit caused by an external factor or if it were left in a high-temperature environment, the provision of foam particles made of an anti-ignition material prevents the spread of fire within the container, even if a short circuit caused by an external factor occurs when the electricity storage device is stored in a container for transportation or storage, or if it ignites or explodes when it is left in a high-temperature environment, thereby reducing the risk of fire spreading outside the container.

[0042] The container for an electricity storage device of the present invention has been described above, but the present invention is not particularly limited in size or shape of the electricity storage device (including an electricity storage device stack in which multiple electricity storage devices are stacked), as long as foamed particles of a thermally depolymerizable polymer are disposed in the gap between the electricity storage device (electricity storage device stack) and the container body. Therefore, the container can be applied to electricity storage devices for various purposes, such as electricity storage devices (electricity storage device stacks) of a wide range of sizes, from smartphones to in-vehicle devices. [Example]

[0043] The present invention will be described in more detail based on the following specific examples, but the present invention is not limited to the following examples.

[0044] [Production of expanded particles of thermally depolymerizable polymer] In this example, the expanded particles of the thermally depolymerizable polymer were produced by the following method based on the method described in JP-A-2007-314774.

[0045] The internal volume is 1m with a stirring device. 3Into the autoclave, 430 kg of deionized water, 0.4 kg of tribasic calcium phosphate (manufactured by Taihei Chemical Industry Co., Ltd.) as a suspending agent, 70 g of disodium dodecyl diphenyl ether sulfonate (manufactured by Kao Corporation: Pelex SSH 50% aqueous solution) as a surfactant, and 0.65 kg of sodium acetate as an electrolyte were charged. Next, 1.5 kg of benzoyl peroxide (Niper BW, water-dilutable powder, manufactured by Nippon Oil & Fats Co., Ltd.) as a polymerization initiator, 0.4 kg of t-butylperoxy-2-ethylhexyl monocarbonate (Perbutyl E, manufactured by Nippon Oil & Fats Co., Ltd.), 3.1 kg of liquid paraffin (Moresco White P60, average carbon number 20, manufactured by Moresco Corporation) as a network former, and 0.6 kg of α-methylstyrene dimer (Nofumer MSD, manufactured by Nippon Oil & Fats Co., Ltd.) as a chain transfer agent were dissolved in 233 kg of methyl methacrylate, 56 kg of styrene, and 22 kg of α-methylstyrene, and the solution was charged into an autoclave while stirring at 110 rpm. After replacing the atmosphere inside the autoclave with nitrogen, the temperature was raised to 80°C over 1.5 hours. During the temperature increase to 80°C, 0.8 kg of a 0.02% aqueous solution of potassium persulfate was added as a suspension aid when the temperature reached 60°C. After reaching 80°C, the autoclave was heated to 115°C over 6 hours, held at 115°C for 5 hours, and then cooled to 30°C over approximately 6 hours. While the temperature was rising from 80°C to 115°C, 37 kg of pentane (a mixture of 80% n-pentane and 20% isopentane) was added to the autoclave over approximately 60 minutes when the temperature reached 110°C. After the blowing agent was added, the stirring speed was reduced to 90 rpm. After cooling, the contents were removed, and nitric acid was added to dissolve the tribasic calcium phosphate adhering to the surface of the expandable acrylic resin particles. The particles were then dehydrated and washed in a centrifuge, and the surface moisture was removed using an airflow dryer to obtain expandable acrylic resin particles with an average particle size of approximately 0.8 mm. The resulting expandable acrylic resin particles were sieved to separate particles with diameters of 0.5 to 1.2 mm. To 100 parts by weight of these expandable acrylic resin particles, 0.015 parts by weight of the antistatic agent N,N-bis(2-hydroxyethyl) alkylamine was added, and the particles were further coated with a mixture of 0.2 parts by weight of zinc stearate and 0.1 parts by weight of glycerin monostearate.12.5 kg of the obtained expandable acrylic resin particles were heated in a pressure batch expansion machine (DYH850, manufactured by Daisen Kogyo Co., Ltd.) by supplying steam so that the pressure inside the expansion machine became 0.01 MPa (gauge pressure), and the steam pressure was maintained for about 80 seconds until the bulk density became about 20 kg / m. 3 As a result, foamed acrylic resin particles were obtained.

[0046] [Nail penetration test] (Comparative Example 1) A polypropylene (PP) resin container (inner diameter: 80 mm wide x 105 mm long x 34 mm deep, resin thickness: 2 mm) was prepared as the internal container for an energy storage device. The electrode side of an aluminum-laminated lithium-ion battery could be placed on the 80 mm side of the container. The PP resin container had five 10 mm diameter holes on the 80 mm side, creating an open top. A fully charged 1500 mAh aluminum-laminated lithium-ion battery (35 mm wide x 75 mm long) was placed inside the PP resin container. A 4 mm thick PP resin plate was placed over the battery and sealed tightly with heat-resistant tape around the edges. This configuration ensured that any debris ejected from the lithium-ion battery during a nail penetration test would be released only through the five holes.

[0047] This PP resin container intended as the inner container for the electricity storage device was placed inside a PP resin container intended as a transport or storage container (inner diameter: 98 mm wide x 148 mm long x 48 mm deep, resin thickness: 2 mm, a container with an open top and five 10 mm diameter holes drilled on the 98 mm wide side (a container with holes drilled on the opposite side to the holes in the PP resin container intended as the container for the above electricity storage device)), and the container was covered with a 4 mm thick PP resin plate.The edges of the lid were sealed using heat-resistant tape so that there were no gaps, and the battery ejection during the nail penetration test was to be released only through the five drilled holes, creating a container for the electricity storage device.

[0048] When a nail penetration test was conducted on this electricity storage device container, the lithium-ion battery was destroyed and a violent fire was confirmed on the outside of the transport container.

[0049] Example 1 In the container for the electricity storage device used in Comparative Example 1, 40 g of expanded particles of acrylic resin (particle size 1 mm) obtained in the above-mentioned "Production of expanded particles of thermally depolymerizable polymer" as expanded particles of thermally depolymerizable polymer were placed in the gap between the container for the electricity storage device to form a container for the electricity storage device.

[0050] When this electricity storage device container was subjected to a nail penetration test under the same conditions as in Comparative Example 1, the battery was destroyed, but no ignition was observed outside the container.

[0051] [Overcharge test] Assuming a situation in which the energy storage device stored in the container in question were to catch fire for some reason, the energy storage device was overcharged and evaluated inside a UN cardboard box or steel container.

[0052] (Comparative Example 2) UN cardboard [product number] 4GV-23 / 17 ([internal dimensions] 325mm x 245mm x 300mmH, [external dimensions] 340mm x 265mm x 335mmH) was assembled with cloth tape, and a laminated lithium-ion battery with a positive electrode ternary system and a capacity of 3200mAh was placed inside.

[0053] When this energy storage device container was overcharged at 15V and 9.6A, the battery was destroyed after about 19 minutes and a violent fire was confirmed on the outside of the energy storage device container.

[0054] Example 2 In the container for the energy storage device used in Comparative Example 2, 70 g of the foamed acrylic resin particles (particle diameter 1 mm) obtained above as the foamed particles of the thermally depolymerizable polymer were placed in a mesh bag measuring 350 x 250 mm and having a mesh diameter of 0.5 mm, and this container was placed on the bottom of the container for the energy storage device.A laminated lithium ion battery with a positive electrode ternary system and a capacity of 3200 mAh was placed on top of this, and a container with 70 g of the foamed acrylic resin particles (particle diameter 1 mm) placed in a mesh bag measuring 350 x 250 mm and having a mesh diameter of 0.5 mm was also placed on top of this.

[0055] When this energy storage device container was overcharged at 15V and 9.6A, the battery was destroyed, but no fire was observed outside the container.

[0056] (Comparative Example 3) A 3200mAh laminated lithium-ion battery was placed inside a steel container (internal dimensions: 300mm x 300mm x 300mmH) made of 1.6mm thick flat plates.

[0057] When this energy storage device container was overcharged at 15V and 9.6A, the battery was destroyed after about 19 minutes and a violent fire was confirmed on the outside of the energy storage device container through a gap.

[0058] Example 3 In the container for the energy storage device used in Comparative Example 3, 70 g of the foamed acrylic resin particles (particle diameter 1 mm) obtained above as foamed particles of the thermally depolymerizable polymer were placed in a mesh bag measuring 300 x 300 mm and having a mesh diameter of 0.5 mm, and this container was attached to six inner surfaces of the container for the energy storage device.A 3200 mAh positive electrode ternary laminated lithium ion battery was then placed on top of this, and a further container containing 70 g of the foamed acrylic resin particles (particle diameter 1 mm) placed in a mesh bag measuring 300 x 300 mm and having a mesh diameter of 0.5 mm was placed on top of this.

[0059] When this container for the electricity storage device was overcharged at 15V and 9.6A, the battery was destroyed, but no fire was observed outside the container.

Claims

1. A container for an electricity storage device, in which foamed particles of a thermally depolymerizable polymer are disposed in a gap between the electricity storage device and a container body that houses the electricity storage device.

2. The container for an electricity storage device according to claim 1 , wherein the electricity storage device uses a non-aqueous electrolyte.

3. 2 . The container for an electricity storage device according to claim 1 , wherein the expanded particles of the thermally depolymerizable polymer contain the thermally depolymerizable polymer in an amount of 10% by weight or more based on the total weight of the expanded particles of the thermally depolymerizable polymer.

4. 2. The container for an electricity storage device according to claim 1, wherein the expanded particles of the thermally depolymerizable polymer are expanded particles of a polymer (homopolymer or copolymer of two or more components) using one or more of methyl methacrylate (MMA), α-methylstyrene (AMS), and tetrafluoroethylene (TFE) as monomer components.

5. The container for an electricity storage device according to claim 1 , wherein the expanded particles of the thermally depolymerizable polymer are in the shape of beads or spheres.

6. 6. The container for an electricity storage device according to claim 5, wherein the bead-shaped or spherical expanded particles have a particle size of 0.5 mm to 20 mm.

7. The electricity storage device transport container according to claim 6, wherein the bead-shaped or spherical bead-shaped or spherical expanded particles are contained in a mesh bag or cage, and the mesh diameter is 0.3 mm to 7 mm and is smaller than the minimum particle size of the bead-shaped or spherical bead-shaped or spherical expanded particles.

8. 7. The container for an electricity storage device according to claim 6, wherein the density of the sheet-like or plate-like expanded beads is 18 g / L to 20 g / L.

9. The container for an electricity storage device according to any one of claims 1 to 8, wherein a plurality of the electricity storage devices are stacked.