Electricity storage device structure

Abstract

To provide a storage device structure capable of reducing the risk of fire when an electric storage device, particularly an electric storage device stack in which a plurality of electric storage devices are stacked, is damaged or overcharged.SOLUTION: A storage device structure is composed of a power storage device and a casing that encloses the power storage device with a gap therebetween, and has a structure in which a molded body containing an acrylic pressure-sensitive adhesive is placed in the gap between the power storage device and the casing. This molded body is preferably tape-shaped, film-shaped, or sheet-shaped.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an electricity storage device structure that encapsulates an electricity storage device such as a lithium ion battery, a lithium ion capacitor, or an electric double layer capacitor, and in particular to an electricity storage device structure that can reduce the risk of fire in the event of an abnormality such as damage to the electricity storage device or overcharging. [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 with a non-flammable gas, aqueous solvent, or 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). [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 an electricity storage device structure that can reduce the risk of fire in the event of an abnormality such as damage or overcharging of an electricity storage device, particularly an electricity storage device stack in which multiple electricity storage devices are stacked. [Means for solving the problem]

[0010] In order to solve the above problems, the present invention provides an electricity storage device structure comprising an electricity storage device and a casing that encases the electricity storage device with a gap therebetween, in which a molded body containing an acrylic pressure-sensitive adhesive is disposed in the gap between the electricity storage device and the casing (Invention 1).

[0011] According to this invention (Invention 1), by placing a molded body containing an acrylic adhesive in the space of a casing that encases an electricity storage device, rather than inside the electricity storage device, the risk of fire spreading outside the casing in the event of a fire occurring inside the electricity storage device can be reduced.

[0012] In the above invention (invention 1), it is preferable that the electricity storage device uses a non-aqueous electrolyte (invention 2).

[0013] In the above inventions (Inventions 1 and 2), the molded article containing the acrylic pressure-sensitive adhesive preferably contains an acrylic polymer portion in an amount of 10% by weight or more of the total weight (Invention 3).

[0014] According to this invention (Invention 3), it is possible to preferably exert the effect of preventing the fire from spreading to the outside when a fire breaks out inside the electricity storage device.

[0015] In the above inventions (Inventions 1 to 3), it is preferable that the acrylic adhesive is an adhesive having an acrylic polymer (homopolymer or copolymer) as a base polymer, which uses one or more (meth)acrylic acid alkyl esters as monomer components (Invention 4).

[0016] In the above inventions (Inventions 1 to 4), the molded article containing the acrylic pressure-sensitive adhesive is preferably in the form of a tape, film or sheet (Invention 5).

[0017] According to this invention (Invention 5), by making it into a tape, film or sheet form, it can be attached inside a casing or inserted into a gap, allowing for a wide variety of installation options and making it easy to handle.

[0018] In the above invention (invention 5), it is preferable that the tape-, film-, or sheet-shaped molded product has a thickness of 1 μm to 5000 μm (invention 6). In particular, in the above invention (invention 5 or 6), the weight per area of ​​the tape-, film-, or sheet-shaped molded product is 10 g to 2000 g / m. 2 It is preferable that (Invention 7).

[0019] According to such inventions (Inventions 6 and 7), by placing a tape-, film- or sheet-shaped molded body of a predetermined thickness and weight 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.

[0020] In the above inventions (Inventions 1 to 7), a plurality of the electricity storage devices may be stacked (Invention 8).

[0021] In an electricity storage device stack in which multiple electricity storage devices are stacked, even if one electricity storage device falls into an overcharged state, the other electricity storage devices continue to function and a large current continues to flow, so the device is easily overheated and the flammable gas is likely to exceed its ignition temperature. In this case, according to this invention (Invention 8), even if flammable gas is ejected from the electricity storage device and flows into the space in the casing, the material of the present invention has an effect on the flammable gas, thereby significantly reducing the risk of the fire spreading outside the casing, making it particularly suitable for application to electricity storage device stacks. [Effects of the Invention]

[0022] The present invention places a molded body containing an acrylic adhesive in the gap between the electricity storage device and the casing, thereby significantly reducing the risk of the electricity storage device structure catching fire due to components generated by the thermal decomposition of the acrylic adhesive caused by high-temperature ejecta and gas emitted from the electricity storage device due to a short circuit or the like. DETAILED DESCRIPTION OF THE INVENTION

[0023] The electricity storage device structure of the present invention will be described in detail below based on the following embodiments.

[0024] [Electricity storage device structure] The electricity storage device structure of this embodiment comprises an electricity storage device and a casing that encases the electricity storage device with a gap therebetween, and has a structure in which a molded body containing an acrylic adhesive is disposed in the gap between the electricity storage device and the casing.

[0025] (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, and all-solid-state batteries are suitable applications of the battery material of this embodiment.

[0026] 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.

[0027] The above-described electricity storage device may be in the form of an electricity storage device stack in which a plurality of such devices are stacked. An electricity storage device stack is particularly suitable because, even if one electricity storage device falls into an overcharged state, the other electricity storage devices continue to function and a large current continues to flow, and therefore, when flammable gas is generated due to the nonaqueous electrolyte, the temperature is likely to exceed the ignition temperature.

[0028] (Casing) In this embodiment, the casing is not particularly limited as long as it can enclose the above-mentioned electricity storage device (electricity storage device stack) with a gap therebetween, and examples thereof include a storage case for the electricity storage device (electricity storage device stack) such as a battery case, a housing for equipment that uses the electricity storage device (electricity storage device stack), etc. The material of this casing is not limited, and it can be made of synthetic resin, metal, or the like.

[0029] (fire-preventive material) In this embodiment, a molded body containing an acrylic adhesive is placed as the fire prevention material placed in the gap between the electricity storage device and the casing.

[0030] (acrylic adhesive) Examples of the acrylic adhesive include an acrylic adhesive having an acrylic polymer (homopolymer or copolymer) as a base polymer, which uses one or more (meth)acrylic acid alkyl esters as a monomer component.

[0031] The acrylic polymer preferably has an alkyl ester having 4 or more carbon atoms as a side chain, more preferably an alkyl ester having 6 or more carbon atoms, even more preferably an alkyl ester having 8 or more carbon atoms, particularly preferably an alkyl ester having 8 to 20 carbon atoms, and most preferably an alkyl ester having 8 to 18 carbon atoms. In the acrylic polymer, the content of structural units having an alkyl ester having 4 or more carbon atoms as a side chain is preferably 30% by weight or more, more preferably 50% by weight or more, even more preferably 70% by weight to 100% by weight, and particularly preferably 80% by weight to 100% by weight, based on all structural units constituting the acrylic polymer.

[0032] The acrylic pressure-sensitive adhesive may contain multiple types of acrylic polymers, and the content of the acrylic polymer having an alkyl ester having 4 or more carbon atoms in the side chain is preferably 30 to 100 parts by weight, more preferably 70 to 100 parts by weight, per 100 parts by weight of the total acrylic polymers.

[0033] Specific examples of the (meth)acrylic acid alkyl ester include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, C1-20 alkyl (meth)acrylate esters such as nonyl acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, nonadecyl (meth)acrylate, and eicosyl (meth)acrylate. Among these, preferred are (meth)acrylic acid alkyl esters having a linear or branched alkyl group having 4 to 20 carbon atoms (more preferably 6 to 20, and particularly preferably 8 to 18), and more preferably 2-ethylhexyl (meth)acrylate.

[0034] The acrylic polymer may contain, as necessary, units corresponding to other monomer components copolymerizable with the alkyl (meth)acrylate, for the purpose of modifying properties such as cohesive strength, heat resistance, and crosslinkability. Examples of such monomer components include carboxyl group-containing monomers such as acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid; acid anhydride monomers such as maleic anhydride and itanoic anhydride; hydroxyl group-containing monomers such as hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, hydroxyhexyl (meth)acrylate, hydroxyoctyl (meth)acrylate, hydroxydecyl (meth)acrylate, hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl)methyl methacrylate; sulfonic acid group-containing monomers such as styrenesulfonic acid, allylsulfonic acid, 2-(meth)acrylamido-2-methylpropanesulfonic acid, (meth)acrylamidopropanesulfonic acid, sulfopropyl (meth)acrylate, and (meth)acryloyloxynaphthalenesulfonic acid; (N-substituted) amide monomers such as methylol (meth) acrylamide, N,N-dimethyl (meth) acrylamide, N-butyl (meth) acrylamide, N-methylol (meth) acrylamide, and N-methylol propane (meth) acrylamide; aminoalkyl (meth) acrylate monomers such as aminoethyl (meth) acrylate, N,N-dimethylaminoethyl (meth) acrylate, and t-butylaminoethyl (meth) acrylate; alkoxyalkyl (meth) acrylate monomers such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate; maleimide monomers such as N-cyclohexyl maleimide, N-isopropyl maleimide, N-lauryl maleimide, and N-phenyl maleimide; itaconimide monomers such as N-methyl itaconimide, N-ethyl itaconimide, N-butyl itaconimide, N-octyl itaconimide, N-2-ethylhexyl itaconimide, N-cyclohexyl itaconimide, and N-lauryl itaconimide;succinimide-based monomers such as N-(meth)acryloyloxymethylene succinimide, N-(meth)acryloyl-6-oxyhexamethylene succinimide, and N-(meth)acryloyl-8-oxyoctamethylene succinimide; vinyl-based monomers such as vinyl acetate, vinyl propionate, N-vinylpyrrolidone, methylvinylpyrrolidone, vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole, vinyloxazole, vinylmorpholine, N-vinylcarboxylic acid amides, styrene, α-methylstyrene, and N-vinylcaprolactam; cyanoacrylate monomers such as acrylonitrile and methacrylonitrile; epoxy group-containing acrylic monomers such as glycidyl (meth)acrylate; polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, and methoxyethyl (meth)acrylate. Glycol-based acrylic ester monomers such as ethylene glycol and methoxypolypropylene glycol (meth)acrylate; acrylic ester monomers having a heterocycle, a halogen atom, a silicon atom, or the like, such as tetrahydrofurfuryl (meth)acrylate, fluorine (meth)acrylate, and silicone (meth)acrylate; polyfunctional monomers such as hexanediol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, epoxy acrylate, polyester acrylate, and urethane acrylate; olefin-based monomers such as isoprene, butadiene, and isobutylene;Examples include vinyl ether-based monomers such as vinyl ether. These monomer components may be used alone or in combination of two or more. Among the above, more preferred are carboxyl group-containing monomers (particularly preferably acrylic acid) or hydroxyl group-containing monomers (particularly preferably hydroxyethyl (meth)acrylate). The content of the structural units derived from the carboxyl group-containing monomer is preferably 0.1 to 10% by weight, more preferably 0.5 to 5% by weight, and particularly preferably 1 to 4% by weight, based on all structural units constituting the acrylic polymer. Furthermore, the content of the structural units derived from the hydroxyl group-containing monomer is preferably 0.1 to 20% by weight, more preferably 0.5 to 10% by weight, and particularly preferably 1 to 7% by weight, based on all structural units constituting the acrylic polymer.

[0035] The acrylic pressure-sensitive adhesive may contain any suitable additives as needed, such as crosslinkers, tackifiers, plasticizers (e.g., trimellitate ester plasticizers, pyromellitate ester plasticizers, etc.), pigments, dyes, fillers, antioxidants, conductive materials, antistatic agents, UV absorbers, light stabilizers, release modifiers, softeners, surfactants, flame retardants, and antioxidants.

[0036] Examples of the crosslinking agent contained in the acrylic pressure-sensitive adhesive include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, melamine-based crosslinking agents, peroxide-based crosslinking agents, as well as urea-based crosslinking agents, metal alkoxide-based crosslinking agents, metal chelate-based crosslinking agents, metal salt-based crosslinking agents, carbodiimide-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, and amine-based crosslinking agents. Of these, isocyanate-based crosslinking agents and epoxy-based crosslinking agents are preferred.

[0037] Specific examples of the isocyanate-based crosslinking agent contained in the acrylic pressure-sensitive adhesive include lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate; alicyclic isocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate and isophorone diisocyanate; aromatic isocyanates such as 2,4-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate and xylylene diisocyanate; and isocyanate adducts such as trimethylolpropane / tolylene diisocyanate trimer adduct (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name "Coronate L"), trimethylolpropane / hexamethylene diisocyanate trimer adduct (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name "Coronate HL"), and hexamethylene diisocyanate isocyanurate (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name "Coronate HX"). The content of the isocyanate-based crosslinking agent can be set to any appropriate amount depending on the desired adhesive strength, and is typically 0.1 to 20 parts by weight, and more preferably 0.5 to 10 parts by weight, per 100 parts by weight of the base polymer.

[0038] Examples of the epoxy crosslinking agent contained in the acrylic pressure-sensitive adhesive include N,N,N',N'-tetraglycidyl-m-xylylenediamine, diglycidylaniline, 1,3-bis(N,N-glycidylaminomethyl)cyclohexane (manufactured by Mitsubishi Gas Chemical Company, Inc., trade name "Tetrad C"), 1,6-hexanediol diglycidyl ether (manufactured by Kyoeisha Chemical Co., Ltd., trade name "Epolite 1600"), neopentyl glycol diglycidyl ether (manufactured by Kyoeisha Chemical Co., Ltd., trade name "Epolite 1500NP"), and the like. ), ethylene glycol diglycidyl ether (manufactured by Kyoeisha Chemical Co., Ltd., trade name "Epolite 40E"), propylene glycol diglycidyl ether (manufactured by Kyoeisha Chemical Co., Ltd., trade name "Epolite 70P"), polyethylene glycol diglycidyl ether (manufactured by NOF Corporation, trade name "Epiol E-400"), polypropylene glycol diglycidyl ether (manufactured by NOF Corporation, trade name "Epiol P-200"), sorbitol polyglycidyl ether (manufactured by Nagase ChemteX Corporation, trade name "Denacol" Examples of suitable crosslinking agents include glycerol polyglycidyl ether (manufactured by Nagase ChemteX Corporation under the trade name "Denacol EX-611"), glycerol polyglycidyl ether (manufactured by Nagase ChemteX Corporation under the trade name "Denacol EX-314"), pentaerythritol polyglycidyl ether, polyglycerol polyglycidyl ether (manufactured by Nagase ChemteX Corporation under the trade name "Denacol EX-512"), sorbitan polyglycidyl ether, trimethylolpropane polyglycidyl ether, adipic acid diglycidyl ester, o-phthalic acid diglycidyl ester, triglycidyl tris(2-hydroxyethyl)isocyanurate, resorcinol diglycidyl ether, bisphenol-S-diglycidyl ether, and epoxy resins having two or more epoxy groups in the molecule. The content of the epoxy crosslinking agent can be set at any appropriate amount depending on the desired adhesive strength, and is typically 0.01 to 10 parts by weight, and more preferably 0.03 to 5 parts by weight, per 100 parts by weight of the base polymer.

[0039] The tackifier contained in the acrylic pressure-sensitive adhesive may be any appropriate tackifier, such as a tackifying resin. Specific examples of the tackifying resin include rosin-based tackifying resins (e.g., unmodified rosin, modified rosin, rosin phenol-based resins, rosin ester-based resins, etc.), terpene-based tackifying resins (e.g., terpene-based resins, terpene phenol-based resins, styrene-modified terpene-based resins, aromatic-modified terpene-based resins, hydrogenated terpene-based resins), hydrocarbon-based tackifying resins (e.g., aliphatic hydrocarbon resins, aliphatic cyclic hydrocarbon resins, aromatic hydrocarbon resins (e.g., styrene-based resins, xylene-based resins, etc.), aliphatic / aromatic petroleum resins, aliphatic / alicyclic petroleum resins, hydrogenated hydrocarbon resins, coumarone-based resins, coumarone-indene resins, etc.), phenol-based tackifying resins (e.g., alkylphenol-based resins, xylene-formaldehyde-based resins, resols, novolacs, etc.), ketone-based tackifying resins, polyamide-based tackifying resins, epoxy-based tackifying resins, and elastomer-based tackifying resins. Among these, rosin-based tackifying resins, terpene-based tackifying resins, and hydrocarbon-based tackifying resins (such as styrene-based resins) are preferred. The tackifiers may be used alone or in combination of two or more. The amount of the tackifier added is preferably 5 to 100 parts by weight, more preferably 10 to 50 parts by weight, per 100 parts by weight of the base polymer.

[0040] Preferably, a resin with a high softening point or glass transition temperature (Tg) is used as the tackifier resin. By using a resin with a high softening point or glass transition temperature (Tg), it is possible to form a pressure-sensitive adhesive layer that can exhibit high adhesiveness even in a high-temperature environment (for example, a high-temperature environment in processing such as when sealing a semiconductor chip). The softening point of the tackifier is preferably 100°C to 180°C, more preferably 110°C to 180°C, and even more preferably 120°C to 180°C. The glass transition temperature (Tg) of the tackifier is preferably 100°C to 180°C, more preferably 110°C to 180°C, and even more preferably 120°C to 180°C.

[0041] Preferably, a low-polarity tackifier resin is used as the tackifier resin. Use of a low-polarity tackifier resin allows for the formation of a pressure-sensitive adhesive layer with low affinity to the sealing material. Examples of low-polarity tackifier resins include hydrocarbon tackifier resins such as aliphatic hydrocarbon resins, aliphatic cyclic hydrocarbon resins, aromatic hydrocarbon resins (e.g., styrene-based resins, xylene-based resins, etc.), aliphatic / aromatic petroleum resins, aliphatic / alicyclic petroleum resins, and hydrogenated hydrocarbon resins. Among these, tackifiers having 5 to 9 carbon atoms are preferred. This is because such tackifiers have low polarity, excellent compatibility with acrylic polymers, do not undergo phase separation over a wide temperature range, and are capable of forming a pressure-sensitive adhesive layer with excellent stability.

[0042] The acid value of the tackifier resin is preferably 40 or less, more preferably 20 or less, and even more preferably 10 or less. The hydroxyl value of the tackifier resin is preferably 60 or less, more preferably 40 or less, and even more preferably 20 or less.

[0043] In this embodiment, the shape of the molded article to be placed in the gap between the electricity storage device and the casing is not particularly limited, but in consideration of ease of handling when placing it in the gap between the electricity storage device and the casing, it is preferable that it be in the form of a tape, film, or sheet. By making the fire-preventing material in the form of a tape, film, or sheet, it can be attached to the inside of the casing or inserted into a gap, allowing for a wide variety of installation options.

[0044] When the acrylic pressure-sensitive adhesive is used to form a tape, film, or sheet, the substrate may include, but is not limited to, paper, nonwoven fabric, resin film (PET, polyimide, etc.), metal foil, acrylic foam, woven fabric, expanded butyl rubber, etc. In some cases, the acrylic pressure-sensitive adhesive alone may be used to form a tape, film, or sheet without using these substrates.

[0045] 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.

[0046] The above-mentioned fire prevention materials may be used alone or in combination of two or more materials.

[0047] The electricity storage device structure 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 molded article containing an acrylic pressure-sensitive adhesive is placed in the gap between the electricity storage device (electricity storage device stack) and the casing. Therefore, the present invention is applicable to electricity storage devices (electricity storage device stacks) of a wide range of sizes, from smartphones to in-vehicle devices. [Example]

[0048] 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. [Overcharge test]

[0049] (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 side of the PP resin container, and five 10 mm diameter holes were drilled on the 80 mm side of the PP resin container, leaving the top open) was prepared as a container for an energy storage device. A 1500 mAh aluminum-laminated lithium-ion battery (35 mm wide, 75 mm long) with a positive electrode ternary system was placed inside the PP resin container, and a 4 mm thick PP resin plate was placed on top of it, sealing the edges of the lid tightly with heat-resistant tape. This configuration ensured that any ejection material from the lithium-ion battery due to overcharge would be released only through the five holes.

[0050] A PP resin container intended for the casing container (inner diameter: 98 mm wide x 148 mm long x 48 mm deep, resin thickness: 2 mm, 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 on the PP resin container intended for the above-mentioned energy storage device container)) was placed outside the PP resin container intended for the energy storage device container, and wiring was installed so that the battery could be overcharged.A 4 mm thick PP resin plate was then placed over the top to cover the lid, and the edges of the lid were sealed using heat-resistant tape to ensure there were no gaps, so that any ejection from the battery in the event of overcharge would be released only through the five holes, completing an energy storage device structure.

[0051] When this energy storage device structure was overcharged at 15V and 7.5A, the battery was destroyed after about 19 minutes and a violent fire was observed on the outside of the casing.

[0052] Example 1 In the electricity storage device structure used in Comparative Example 1, a double-sided tape (thickness 160 μm, weight per area 180 g / m) to which an acrylic adhesive was applied was used. 2 The base material is nonwoven fabric) was attached to the top surface of the inside of the PP resin plate of the top cover of the PP resin container, which was assumed to be a casing, with a thickness of 0.011 mm. 2 The resulting structure was a power storage device.

[0053] When this electricity storage device structure was overcharged under the same conditions as in Comparative Example 1, ie, at 15 V and 7.5 A, the battery was destroyed after about 19 minutes, but no fire was observed outside the casing.

[0054] Example 2 In the electricity storage device structure used in Comparative Example 1, a double-sided tape (thickness 45 μm, weight per area 100 g / m) to which an acrylic adhesive was applied was used. 2 The base material is polyimide) is attached to the top surface of the inside of the PP resin plate of the top cover of the PP resin container assumed to be a casing. 2 The resulting structure was a power storage device.

[0055] When this electricity storage device structure was overcharged under the same conditions as in Comparative Example 1, ie, at 15 V and 7.5 A, the battery was destroyed after about 19 minutes, but no fire was observed outside the casing.

Claims

1. An electricity storage device structure including an electricity storage device and a casing that encases the electricity storage device with a gap therebetween, a molded body containing an acrylic adhesive is placed as an ignition prevention material in a gap between the electricity storage device and a casing; the molded article containing the acrylic pressure-sensitive adhesive is in the form of a tape, film, or sheet, The tape-, film-, or sheet-shaped body has a thickness of 1 μm to 160 μm.

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

3. 3. The electricity storage device structure according to claim 1, wherein the molded body containing the acrylic pressure-sensitive adhesive contains an acrylic polymer portion in an amount of 10% by weight or more of the total weight.

4. The electricity storage device structure according to any one of claims 1 to 3, wherein the acrylic pressure-sensitive adhesive is an acrylic pressure-sensitive adhesive having, as a base polymer, an acrylic polymer (homopolymer or copolymer) using one or more (meth)acrylic acid alkyl esters as monomer components.

5. The weight per unit area of ​​the tape-, film-, or sheet-shaped molded product is 10 g / m to 2000 g / m ２ The electricity storage device structure according to any one of claims 1 to 4, wherein

6. The electricity storage device structure according to any one of claims 1 to 5, wherein a plurality of the electricity storage devices are stacked.