Container for power storage device

Abstract

A container for a power storage device of the present embodiment is a container for a power storage device such as a transport container for when a single or a plurality of power storage devices are externally packaged and transported or moved, or a storage container for when a single or a plurality of power storage devices are externally packaged and stored. This container for a power storage device has a structure in which a thermally-depolymerizable polymer foam molded body is disposed in a gap between a container body that houses the power storage device and a region where the power storage device is housed in the container body. Such a container for a power storage device makes it possible to reduce the risk of fire spreading to the outside of the container when an abnormality occurs in a high-temperature environment or there is damage to the power storage device.

Description

Containers for electricity storage devices

[0001] The present invention relates to a container for an electricity storage device, such as a transport container for packaging and transporting an electricity storage device such as a lithium ion battery, a lithium ion capacitor, or an electric double layer capacitor, or a storage container for packaging and storing such an electricity storage device, and in particular to a container for an electricity storage device that can reduce the risk of fire spreading outside the container even if the electricity storage device catches fire in the event of damage or an abnormality such as a high-temperature environment.

[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 in individual electricity storage devices or in modules in which multiple electricity storage devices are stacked are increasing. 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 technology for preventing ignition of such an electricity storage device, 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] On the other hand, 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 in the pores and on the surface is placed inside the lithium-ion battery to prevent fires caused by gas generated from the lithium-ion battery (Patent Document 4).

[0007] JP 2001-155790 A JP 2003-077549 A JP 2010-287488 A JP 2013-187089 A

[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 both 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 a non-flammable gas or an aqueous solvent or a 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 view of the above-mentioned problems, and aims to provide a container for an electricity storage device, such as a transport container for packaging and transporting a single or multiple electricity storage devices, or a storage container for packaging and storing a single or multiple electricity storage devices, which 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.

[0010] In order to solve the above problems, the present invention provides a container for an electricity storage device, in which a foamed molded body of a thermally depolymerizable polymer is 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 nonaqueous electrolyte (Invention 2).

[0011] According to these inventions (Inventions 1 and 2), by placing a foamed molded body of a thermally depolymerizable polymer in the space 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 foamed molded product of the thermally depolymerizable polymer contains 10% by weight or more of the thermally depolymerizable polymer as a whole (Invention 3).In the above invention (Invention 1), it is preferable that the foamed molded product of the thermally depolymerizable polymer is a foamed molded product of 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 (Invention 4).

[0013] According to such inventions (Inventions 3 and 4), when an abnormality occurs in the electricity storage device, it is possible to preferably exert the effect of preventing the spread of fire to the outside of the container.

[0014] In the above invention (invention 1), the foam molded product of the thermally depolymerizable polymer is preferably in the form of a sheet or plate (invention 5). In the above invention (invention 5), the sheet or plate-shaped foam molded product preferably has a thickness of 1 mm to 100 mm (invention 6). In particular, in the above invention (invention 6), the density of the sheet or plate-shaped foam molded product is preferably 18 g to 20 g / L (invention 7).

[0015] According to these inventions (Inventions 5 to 7), by placing a sheet-like or plate-like foamed molded body of a predetermined thickness and density in the gap between the container for the electricity storage device and the container, it is possible to effectively prevent fire from spreading outside the container in the event of an abnormality in the electricity storage device.

[0016] In the above inventions (Inventions 1 to 7), a plurality of the electricity storage devices may be stacked (Invention 8).

[0017] In the above invention (Invention 8), 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 molded body of the thermally depolymerizable polymer affects the flammable gas, thereby significantly reducing the risk of the fire spreading outside the container, and therefore this invention is particularly suitable for application to electricity storage device stacks.

[0018] The container for an electricity storage device of the present invention has a foamed molded body 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 the high-temperature ejected material and gas emitted from the electricity storage device due to a short circuit or the like in the electricity storage device, thereby significantly reducing the risk of the container for the electricity storage device catching fire.

[0019] The container for an electricity storage device of the present invention will be described in detail based on the following embodiments.

[0020] [Container for Electricity Storage Device] The container for an electricity storage device of this embodiment has a structure in which a foamed molded body of a thermally depolymerizable polymer is disposed in the gap between the container body and the area in which the electricity storage device is housed in the container body.

[0021] (Electricity Storage Device) In this embodiment, the electric 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 this secondary battery is not particularly limited, and for example, a lithium ion battery, a lithium ion polymer battery, an all-solid-state battery, a lead acid battery, a nickel-metal hydride battery, a nickel-cadmium battery, a nickel-iron battery, a nickel-zinc battery, a silver oxide-zinc battery, a metal-air battery, a polyvalent cation battery, a condenser, a capacitor, etc. can be used. Among these, those using a nonaqueous electrolyte can be preferably used. Among these secondary batteries, lithium ion batteries, lithium ion polymer batteries, lithium ion capacitors, all-solid-state batteries, etc. can be preferably used as suitable applications of the battery material of the present invention.

[0022] The non-aqueous 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 non-aqueous electrolyte may contain a lithium salt such as lithium hexafluorophosphate dissolved therein as needed. For example, a mixed solution obtained by mixing ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) in a ratio of 1:1:1, or a mixed solution obtained by mixing propylene carbonate (PC), ethylene carbonate (EC), and diethyl carbonate (DEC) in a ratio of 1:1:1 to which 1 mol / L of lithium hexafluorophosphate has been added, may be used.

[0023] The above-described electricity storage device may be in the form of an electricity storage device stack in which a plurality of devices are stacked.

[0024] (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 in the shape of a rectangular box, but is not limited to this. This container body is preferably provided with a release valve or a release hole so that ejected gas or ejected material emitted 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.

[0025] (Ignition Prevention Material) In this embodiment, a foam molded body of a thermally depolymerizable polymer is disposed as an ignition prevention material to be placed in the gap between the electricity storage device and the container body.

[0026] (Thermal Depolymerizable Polymer) In this embodiment, the thermal depolymerizable polymer refers to a polymer that has depolymerization properties in which a polymer is decomposed into monomers by heat or light and leaves no residue when heated. Examples of the thermal depolymerizable polymer include thermal depolymerizable polymers whose base polymer is 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, or 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 (monomers such as styrene) during polymerization of these polymers 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.

[0027] (Foamed Molded Product of Thermally Depolymerizable Polymer) In this embodiment, the foamed molded product 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 using a known method (for example, the method described in JP 2007-314774 A).

[0028] The foamed molded article 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 plasticizer, a pyromellitic ester 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.

[0029] It is also possible to add known fire extinguishing agent components to the foamed molded article, and it is also possible to use a known fire extinguishing agent by sandwiching it between the foamed molded articles of the present invention.

[0030] In this embodiment, the shape of the foam molded article of the ignition prevention material to be placed in the gap between the electricity storage device and the container is not particularly limited, but in consideration of ease of handling when placing it in the gap between the electricity storage device and the container, a sheet or plate shape is preferred. In the case of a sheet or plate-shaped foam molded article, from the viewpoints of handleability and profitability, the thickness is preferably 1 mm to 100 mm, particularly 10 mm to 80 mm. Furthermore, the density of the foam molded article, particularly a sheet or plate-shaped foam molded article, is preferably about 18 g to 20 g / L.

[0031] Furthermore, 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.

[0032] The above-mentioned fire prevention materials may be used alone or in combination of two or more materials.

[0033] [Method of using a container for an electricity storage device] The electricity storage device and container described above may be transported or stored by first placing a foamed molded body of an anti-ignition material in the container body, and then accommodating an electricity storage device with a state of charge (SOC) of, for example, about 30%, sealing the container, or by accommodating an electricity storage device in the container body, placing a foamed molded body of an anti-ignition material in the gap, sealing the container, and transporting or storing it.

[0034] 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 a foam molded body made of an ignition-preventing 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 transported or stored in a container, or if it were to ignite or explode if it were left in a high-temperature environment, thereby reducing the risk of fire spreading outside the container.

[0035] 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 (electricity storage device stack) as long as a foam molded article of a thermally depolymerizable polymer is 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.

[0036] 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.

[0037] [Production of foamed molded article of thermally depolymerizable polymer] In this example, a foamed molded article of a thermally depolymerizable polymer was produced by the following method based on the method described in JP-A-2007-314774.

[0038] The internal volume is 1 m with a stirring device. ３Into an 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 product, manufactured by NOF Corporation) as a polymerization initiator, 0.4 kg of t-butylperoxy-2-ethylhexyl monocarbonate (Perbutyl E, manufactured by NOF Corporation), 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 (Nofmer MSD, manufactured by NOF Corporation) 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 one and a half hours. During the temperature increase to 80°C, when the temperature reached 60°C, 0.8 kg of a 0.02% aqueous solution of potassium persulfate was added as a suspension aid. After reaching 80°C, the temperature was further increased to 115°C over 6 hours, maintained at 115°C for 5 hours, and then cooled to 30°C over approximately 6 hours. While increasing the temperature 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 addition of the blowing agent, 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 contents were then dehydrated and washed in a centrifuge, and the moisture adhering to the surface was removed using an airflow dryer, yielding 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 N,N-bis(2-hydroxyethyl)alkylamine as an antistatic agent 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 to make the bulk density about 20 kg / m. ３ As a result, foamed acrylic resin particles were obtained.

[0039] The resulting foamed beads were placed in an aging silo and aged at room temperature for one day. A block molding machine (VS-2000-5VMC, manufactured by Daisen Kogyo Co., Ltd.) was used to mold the foamed beads into a block. The mold dimensions were 2.0 m long x 1.0 m wide x 0.5 m thick, and heating and demolding were controlled using a pressure gauge attached to the center of the 2.0 m x 1.0 m surface of the mold. Steam was supplied into the mold to heat the foamed acrylic resin beads filled in the mold until the foaming pressure reached a maximum of 0.098 MPa. The mold was then water-cooled for three seconds. The pressure inside the mold cavity was then reduced to -0.06 MPa (gauge pressure). This reduced pressure was maintained until the pressure gauge reached 0.00 MPa (gauge pressure). The mold was then opened, and a block-shaped foamed molded product was removed. The resulting foamed molded product had a density of approximately 19 g / L.

[0040] [Nail Penetration Test] (Comparative Example 1) A PP resin container (inner diameter: 80 mm wide x 105 mm long x 34 mm deep, resin thickness: 2 mm, the electrode side of an aluminum-laminated lithium-ion battery was placed on the 80 mm wide side of the PP resin container, and five 10 mm diameter holes were drilled on the 80 mm wide side of the PP resin container, leaving an open top) was prepared as an internal container for an electricity storage device. A fully charged 1500 mAh aluminum-laminated lithium-ion battery (35 mm wide x 75 mm long) was placed inside the PP resin container, and a 4 mm thick PP resin plate was used to cover the lid, sealing the edges of the lid tightly with heat-resistant tape. The nail penetration test was conducted so that any ejection from the lithium-ion battery during the nail penetration test would be released only through the five holes drilled on the top surface.

[0041] A PP resin container intended for a transport or storage container (inner diameter: 98 mm wide x 148 mm long x 48 mm deep, resin thickness: 2 mm, open-topped container with five 10 mm diameter holes drilled on the 98 mm wide side (a container with holes drilled on the side opposite to the holes drilled on the PP resin container intended for the above-mentioned electricity storage device container)) was placed on the outside of this PP resin container intended for the inner container of the electricity storage device, and a 4 mm thick PP resin plate was used as a lid. Heat-resistant tape was used to seal the edges of the lid so that there were no gaps, and a container for an electricity storage device was created in this way so that ejected material from the battery during a nail penetration test would be released only through the five drilled holes.

[0042] When a nail penetration test was conducted on this electricity storage device container, the battery was destroyed and a violent fire was confirmed on the outside of the container.

[0043] (Example 1) In the container for an electricity storage device used in Comparative Example 1, a plate-shaped molded product (thickness 3 mm, density 19 g / LL) of the foamed acrylic resin obtained above as a foamed molded product of a thermally depolymerizable polymer was attached to the upper surface of the inner side of the PP resin plate of the upper cover of a PP resin container assumed to be a casing, with a thickness of 0.011 m. ２ The container was attached with double-sided tape to form a container for the electricity storage device.

[0044] 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.

[0045] [Overcharge Test] Assuming a situation in which the electricity storage device stored in the container catches fire for some reason, the electricity storage device was overcharged in a UN cardboard box or a steel container and evaluated.

[0046] Comparative Example 2 UN cardboard [product number] 4GV-23 / 17 ([inner dimensions] 325 mm × 245 mm × 300 mmH, [outer dimensions] 340 mm × 265 mm × 335 mmH) was assembled with cloth tape, and a 3200 mAh laminated lithium ion battery with a positive electrode ternary system was placed inside.

[0047] When this electricity storage device container was overcharged at 15 V and 9.6 A, the battery was destroyed after about 19 minutes, and violent ignition was confirmed on the outside of the electricity storage device container.

[0048] (Example 2) In the container for the storage battery device used in Comparative Example 2, a plate-shaped molded product (310 mm x 230 mm x 50 mmH) of the foamed acrylic resin obtained above as a foamed thermally depolymerizable polymer was placed on the bottom surface of the container for the storage battery device, a laminated type lithium ion battery with a positive electrode ternary system and a capacity of 3200 mAh was placed thereon, and another plate-shaped molded product (310 mm x 230 mm x 50 mmH) of the foamed acrylic resin was further placed thereon.

[0049] When this electricity storage device container was overcharged at 15 V and 9.6 A, the battery was destroyed, but no ignition was observed outside the container.

[0050] (Comparative Example 3) A 3200 mAh laminated lithium ion battery was placed inside a steel container (internal dimensions: 300 mm x 300 mm x 300 mmH) made of flat plates with a thickness of 1.6 mm. (Comparative Example 3) When this electricity storage device container was overcharged at 15 V and 9.6 A, the battery was destroyed after about 19 minutes, and violent fire was confirmed on the outside from a gap in the electricity storage device container.

[0051] (Example 3) In the container for the storage battery device used in Comparative Example 3, plate-shaped molded bodies (300 mm × 300 mm × 20 mmH) of the foamed acrylic resin obtained above as a foamed thermally depolymerizable polymer were attached to six inner surfaces of the container for the storage battery device, a 3200 mAh positive electrode ternary laminated lithium ion battery was placed on the bottom, and another plate-shaped molded body (250 mm × 250 mm × 50 mmH) of the foamed acrylic resin was placed on top of that.

[0052] When this electricity storage device container was overcharged at 15 V and 9.6 A, the battery was destroyed, but no ignition was observed outside the container.

Claims

1. A container for an electricity storage device, in which a foamed molded body of a thermally depolymerizable polymer is placed in the 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. The container for an electricity storage device according to claim 1, wherein the foamed molded product of the thermally depolymerizable polymer contains 10% by weight or more of the thermally depolymerizable polymer as a whole.

4. The container for an electricity storage device according to claim 1, wherein the foamed molded product of the thermally depolymerizable polymer is a foamed molded product 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 foamed molded product of the thermally depolymerizable polymer is in the form of a sheet or plate.

6. The container for an electricity storage device according to claim 5, wherein the sheet-like or plate-like foam molded product has a thickness of 1 mm to 100 mm.

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

8. The container for an electricity storage device according to any one of claims 1 to 7, wherein a plurality of the electricity storage devices are stacked.