Stack and power storage device

Abstract

To provide a technique relating to a laminate excellent in fire resistance, heat insulating properties and strength.SOLUTION: A laminate 10 according to an embodiment of the present invention includes a metal sheet 30, a fiber-containing layer 20 laminated on one side of the metal sheet 30, and a silicone foam layer 40 laminated on the other side of the metal sheet 30.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a laminate and an electricity storage device. [Background technology]

[0002] Various types of batteries, such as lithium-ion batteries, are at risk of thermal runaway and ignition due to internal short circuits. In particular, automotive batteries can be at risk of thermal runaway and ignition due to impacts such as vehicle accidents, which could result in a vehicle fire. For this reason, battery covers must be designed to prevent the transfer of heat from abnormally high temperatures caused by thermal runaway to the surrounding area, and to prevent the transfer of flames and heat resulting from a battery ignition to the outside. As covers for such automotive batteries, for example, battery cases formed from metal materials such as iron or aluminum, and laminates having layers containing thermoplastic resins such as polyamide and reinforcing fibers such as glass fibers have been proposed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-294048 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-97883 Summary of the Invention [Problem to be solved by the invention]

[0004] Covers made of metal materials are not only difficult to reduce in weight, but also have the problem of not being able to adequately suppress the transfer of heat generated in the event of a battery ignition, making it impossible to prevent the interior of the vehicle from becoming too hot. On the other hand, while plastic covers are expected to reduce weight, they have the problem of not being able to sufficiently prevent the combustion of the plastic itself. Furthermore, when a lithium-ion battery catches fire, the inorganic materials, such as the active material of the cell components, and the metals, such as the current collector foil, are ejected at high temperature and high speed along with the intense flames, which can cause the plastic cover to be perforated due to its insufficient strength.

[0005] The present invention has been made in view of the above-mentioned problems, and has an object to provide a technology relating to a laminate that is excellent in fire resistance and heat insulation properties as well as strength. [Means for solving the problem]

[0006] One aspect of the present invention is a laminate comprising a metal sheet and a fiber-containing layer and / or a silicone foam layer laminated to the metal sheet. In the laminate of the above aspect, the fiber-containing layer, the metal sheet, and the silicone foam layer may be laminated in this order. The thickness of the metal sheet may be 500 μm or less. The material of the metal sheet may be stainless steel.

[0007] Another aspect of the present invention is a power storage device. The power storage device includes the laminate of any one of the above aspects. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a technology relating to a laminate that is excellent in fire resistance and heat insulation properties as well as strength. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic cross-sectional view of a laminate according to an embodiment. [Figure 2] FIG. 2 is a schematic diagram showing a battery case equipped with a plurality of modules each made up of a plurality of cells. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described in detail. In this specification, the expression "a to b" in the description of a range of numerical values ​​means that the range is from a to b, unless otherwise specified. The average particle diameter D50 (volume basis) of the particles can be determined by a laser diffraction / scattering particle size distribution measuring device.

[0011] (Laminate) 1 is a schematic cross-sectional view of a laminate 10 according to an embodiment. The laminate 10 includes a fiber-containing layer 20, a metal sheet 30, and a silicone foam layer 40. In this embodiment, the fiber-containing layer 20, the metal sheet 30, and the silicone foam layer 40 are laminated in this order.

[0012] <Fiber-containing layer> The fiber-containing layer 20 is laminated on one main surface of the metal sheet 30. The fiber-containing layer 20 and the metal sheet 30 may be bonded together by providing an adhesive layer such as a fusion net, adhesive, or heat-resistant double-sided tape between the fiber-containing layer 20 and the metal sheet 30. The fusion net is not particularly limited as long as it melts when heated and exhibits an adhesive effect, and examples thereof include polyethylene, polypropylene, polyester, and nylon. In particular, when an adhesive is used, an inorganic adhesive is preferred because it can withstand high temperatures. Examples of inorganic adhesives that can be used include silica-based adhesives, which are primarily composed of silica, ceramic-based adhesives, and cement-based adhesives, which are primarily composed of cement. These adhesives can provide better fire resistance than organic adhesives.

[0013] The fiber-containing layer 20 is formed, for example, from non-combustible paper made of inorganic powder, inorganic fibers, and organic fibers. The lower limit of the thickness of the fiber-containing layer 20 is, for example, 20 μm or more, 30 μm or more, or 50 μm or more. The lower limit of the thickness of the fiber-containing layer 20 is, for example, 20 μm or more, 30 μm or more, or 50 μm or more. The lower limit of the thickness of the fiber-containing layer 20 is, for example, 1000 μm or less, 800 μm or less, or 500 μm or less. The non-combustible paper satisfies a flame retardancy rating of V-0 based on the UL94 vertical flame test. Examples of inorganic powders include silicate minerals such as sepiolite, talc, kaolin, mica, and sericite, magnesium carbonate, calcium carbonate, hard clay, calcined clay, barium sulfate, calcium silicate, wollastonite, sodium bicarbonate, synthetic silica such as white carbon and fused silica, natural silica such as diatomaceous earth, aluminum hydroxide, magnesium hydroxide, and glass beads. Examples of inorganic fibers include ceramic fibers such as glass wool, silica fiber, alumina fiber, alumina silicate fiber, and zirconia fiber, and mineral fibers such as rock wool, alkaline earth silicate fiber, zirconia fiber, potassium titanate fiber, and wollastonite. The organic fibers include natural fibers and non-thermofusible synthetic fibers, and one or more of these can be used. Examples of natural fibers include cellulose fibers such as wood pulp (softwood pulp and hardwood pulp), and natural fibers such as cotton, wool, silk, and hemp, and one or more of these can be used. The wood pulp may be beaten or unbeaten pulp. Among these, relatively inexpensive wood pulp is preferred. The non-thermofusible synthetic fibers may be any fibers that do not melt when heated during the inorganic fiber sheet manufacturing process, and can be selected depending on the drying temperature set in the inorganic fiber sheet manufacturing process, but examples include chemical fibers such as polypropylene fibers, polybutene fibers, nylon fibers, rayon fibers, cupra fibers, acetate fibers, polyvinyl chloride fibers, acrylic fibers, polyester fibers, polyurethane fibers, polyparaphenylene benzobisoxazole fibers, polyamideimide fibers, polyimide fibers, polyarylate fibers, polyetherimide fibers, vinylon fibers, polycarbonate fibers, ethylene-vinyl acetate fibers, polyphenylene sulfide fibers, polyethylene terephthalate fibers, polybutylene terephthalate fibers, polyethylene naphthalate fibers, and aramid fibers. One or more types of non-thermofusible synthetic fibers can be used.

[0014] <Metal sheet> Examples of the metal sheet 30 include sheets of aluminum, iron, stainless steel (SUS), copper, gold, silver, etc. Among these, a stainless steel sheet is preferably used. The thickness of the metal sheet 30 is preferably 500 μm or less, more preferably 30 to 400 μm, and even more preferably 40 to 300 μm.

[0015] <Silicone foam> The silicone foam layer 40 is laminated on the other main surface of the metal sheet 30. The silicone foam layer 40 may be integrally molded with the metal sheet 30.

[0016] The silicone foam layer 40 is not particularly limited, and examples thereof include solid-raw-material silicone foams (such as millable silicone foams), liquid-raw-material silicone foams (such as two-component silicone foams), and emulsion-based silicone foams. Millable silicone foams are silicone foams obtained by blending and kneading various additives (fillers, dispersants, vulcanizing agents, etc.) with organopolysiloxane as the primary raw material and thermally curing them. Foamed silicone resins can be obtained by adding a blowing agent (chemical blowing agent) as an additive. Two-component silicone foams are foams that are formed by mixing and stirring two liquid silicone materials, resulting in the formation of bubbles (cells) due to the gas (hydrogen) generated during curing. Emulsion-based silicone foams are foams obtained by emulsifying silicone and water to prepare an emulsion composition, mechanically foaming the emulsion composition, and then curing (drying) it.

[0017] The lower limit of the thickness of the silicone foam layer 40 is, for example, 0.2 mm or more, 0.3 mm or more, or 0.5 mm or more. The upper limit of the thickness of the silicone foam layer 40 is, for example, 5.0 mm or less, 3.0 mm or less, or 2.0 mm or less.

[0018] The lower limit of the density of the silicone foam layer 40 is, for example, 100 kg / m 3 More than 200kg / m 3 More than 300kg / m 3 On the other hand, the upper limit of the density of the silicone foam layer 40 is, for example, 900 kg / m 3 Below 800kg / m 3 Below 700kg / m 3 The following is the result.

[0019] <Silicone foam manufacturing method 1> One method for forming silicone foam is to mix and stir two-component liquid silicone to cause a foaming and curing reaction. Specifically, a self-foaming reaction type silicone foam can be obtained by foaming (by the generated hydrogen gas) and curing through the following reaction, which is carried out in the presence of a catalyst such as a platinum catalyst:

[0020] Reaction 1: Reaction of a silanol-containing organopolysiloxane such as hydroxyl-terminated polydimethylsiloxane or a hydroxyl-containing compound (foaming aid) with an organohydrogenpolysiloxane such as methylhydrogenpolysiloxane having SiH groups at both ends and in the side chains. Reaction 2: Reaction of a vinyl-containing organopolysiloxane, such as dimethylpolysiloxane, whose both ends are blocked with dimethylvinylsiloxy groups, with an organohydrogenpolysiloxane, such as methylhydrogenpolysiloxane, which has SiH groups at both ends and in the side chains.

[0021] In addition, an inert gas such as air or nitrogen may be added when mixing and stirring the two-component liquid silicone raw materials. In this case, the inert gas acts as a foaming nucleus, allowing for the formation of more uniform cells.

[0022] Specific examples of platinum catalysts include chloroplatinic acid, elemental platinum, chloroplatinic acid hexahydrate, complexes of chloroplatinic acid with sym-divinyltetramethyldisiloxane, dichloro-bis(triphenylphosphine)platinum(II), cis-dichlorobis(acetonitrile)platinum(II), dicarbonyldichloroplatinum(II), platinum chloride, platinum oxide, and zero-valent platinum metal complexes, such as Karstedt's catalyst, [Cp*Ru(MeCN)3]PF6, [PtCl2(cyclohexyl)methyldisiloxane], [Cp*Ru(MeCN)3]PF6 ... octadiene), solid platinum supported on a carrier (e.g., alumina, silica, or carbon black), platinum-vinylsiloxane complexes {e.g., Pt(ViMeSiOSiMeVi)c and Pt[(MeViSiO)]d}, platinum-phosphine complexes {e.g., Pt(PPh)4 and Pt(PBU)4}, and platinum-phosphite complexes {e.g., Pt[P(Oph)]4 and Pt[P(Obu)]4}, where "Me" represents methyl, "Bu" represents butyl, "Vi" represents vinyl, and "Ph" represents phenyl, and c and d represent integers.

[0023] The hydroxyl-containing compound (foaming aid) can be water or alcohols such as benzyl alcohol or ethanol. In this case, a stock solution containing a vinyl-containing organopolysiloxane (main polymer), a hydroxyl-containing compound (foaming aid), and a catalyst is prepared as Liquid A, and a stock solution containing a vinyl-containing organopolysiloxane (main polymer) and an organohydrogenpolysiloxane (crosslinking agent) is prepared as Liquid B. Liquid A and Liquid B are mixed and stirred to allow the foaming reaction and curing reaction to proceed. The number-average molecular weight of the main polymer is preferably 500 to 100,000, more preferably 1,000 to 70,000, and even more preferably 1,500 to 50,000. The number-average molecular weight is a value measured by gel permeation chromatography (GPC) using standard polystyrene. When two liquids consisting of liquid A and liquid B are used as described above, the mixing ratio (mass ratio) of liquid A to liquid B varies depending on the density and cell shape of the foam to be obtained, but is typically 100:1 to 100:50.

[0024] The above-mentioned Solution A may contain silica as a reinforcing material. The amount of silica added is not particularly limited, but is generally greater than 0 to 40% by mass based on the total mass of Solution A. Solution A may also contain titanium oxide, aluminum hydroxide, calcium carbonate, etc. as a filler for adjusting viscosity and / or imparting functionality such as strength and flame retardancy. The total content of these fillers is not particularly limited, but is generally greater than 0 to 50% by mass based on the total mass of Solution A.

[0025] The reaction time for hydrogen generation is adjusted as appropriate depending on the density and cell shape of the foam to be obtained. It is usually 1 to 10 minutes, preferably 2 to 6 minutes. The mixing temperature is adjusted as appropriate depending on the density and cell shape of the foam to be obtained. It is usually room temperature.

[0026] The density of the silicone foam layer can be adjusted by optimizing the temperature during hardening and foaming (molding), the amount of foaming aid, and the ratio of liquid A to liquid B (amount of Si-H added).

[0027] <Silicone foam manufacturing method 2> Silicone foams can also be obtained by foaming / curing silicone emulsion compositions.

[0028] The silicone-based resin used in the silicone emulsion composition is not particularly limited as long as it contains a silane compound as a raw material monomer, and examples thereof include dimethyl silicone, methylphenyl silicone, and various modified silicones (e.g., amino-modified silicone, epoxy-modified silicone, polyether-modified silicone emulsion, alkyl-modified silicone emulsion, fluorine-modified silicone, etc.). The silicone emulsion composition can be produced, for example, by blending raw material monomers of the resin components in an aqueous medium and emulsion-polymerizing the raw material monomers in the presence of various additives such as emulsifiers and polymerization initiators. The silicone emulsion composition may also be blended with emulsions containing resins other than silicone-based resins, such as acrylic resins, polyurethane resins, polyester resins, and polyepoxy resins.

[0029] The aforementioned raw materials are mixed to prepare a silicone emulsion composition, which is a mixture of foamed sheet ingredients (preparation step). The mixing method is not particularly limited; for example, the ingredients may be mixed while stirring in a container such as a mixing tank. A predetermined foaming gas is then added to the silicone emulsion composition obtained in the preparation step, and the mixture is thoroughly mixed to create a state in which numerous bubbles exist in the silicone emulsion composition (foamed emulsion composition) (foaming and curing step). This foaming and curing step is typically carried out by thoroughly mixing the liquid foamed sheet ingredient mixture obtained in the raw material preparation step with the foaming gas using a mixing device such as a mixing head. The foaming gas mixed into the emulsion composition in the stirring and foaming step forms the bubbles (cells) in the foam, and the density of the resulting foam is determined by the amount of foaming gas added. To adjust the density of a foam sheet, the weight of the foam sheet raw material required is calculated based on the desired density of the foam sheet and the volume of the foam sheet raw material (e.g., the internal volume of the mold into which the foam sheet raw material is injected), and the amount of foaming gas is determined so that the desired volume is achieved for this weight. Air is typically used as the foaming gas. Other inert gases, such as nitrogen, carbon dioxide, helium, and argon, can also be used. Examples of foaming methods include mechanical froth (mechanical foaming). The mechanical froth method involves mixing atmospheric air into a silicone emulsion composition by stirring it with a stirring blade or the like, thereby foaming the emulsion composition. Any stirrer commonly used in mechanical froth methods can be used without particular limitation, including, for example, a homogenizer, a dissolver, or a mechanical froth foaming machine. The mixing time of the silicone emulsion composition and air is adjusted appropriately depending on the desired density of the foam, and is typically 1 to 10 minutes, preferably 2 to 6 minutes. The mixing temperature is adjusted appropriately depending on the density and cell shape of the foam to be obtained, and is usually room temperature.The stirring speed during mixing is preferably 200 rpm or higher (more preferably 500 rpm or higher) to make the bubbles finer, and is preferably 2000 rpm or lower (more preferably 800 rpm or lower) to allow the foam to be smoothly discharged from the foaming machine.

[0030] The shape of the laminate 10 of this embodiment is not particularly limited, and examples thereof include a square, a circle, and a shape that matches the shape of the case to be protected.

[0031] The laminate 10 of this embodiment is excellent in fire resistance and heat insulation properties, as well as strength.

[0032] (Application) The laminate 10 according to the embodiment can be attached as a protective member to a case for a power storage device that houses the power storage device. Examples of the power storage device include a battery and an electric double layer capacitor. The ion conductor used in the battery is not particularly limited, and may be any well-known ion such as Li ion, Na ion, Mg ion, or Al ion. Of these, a lithium ion battery using Li ion as the ion conductor is preferred.

[0033] FIG. 2 is a schematic diagram showing a battery case 100 having a plurality of modules each made up of a plurality of cells. The battery case 100 has an upper cover 110 and a lower case 120. A plurality of modules 200a to 200d are housed in the battery case 100, and the plurality of modules 200a to 200d are placed on a cushion material 130 placed on the upper surface of the lower case 120. The laminate 10 according to the embodiment is attached to the back surface of the upper cover 110. When the laminate 10 includes a fiber-containing layer 20, it is desirable to arrange the fiber-containing layer 20 so as to face the plurality of modules 200a to 200d. According to this embodiment, the fire resistance and heat insulation properties of the battery case 100 are improved, and even if a module catches fire and ejected material is generated, the ejected material can be prevented from flying out of the battery case 100.

[0034] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various other configurations can also be adopted. For example, in the above embodiment, a three-layer structure is exemplified in which a fiber-containing layer 20 is laminated on one side of the metal sheet 30 and a silicone foam layer 40 is laminated on the other side of the metal sheet 30, but a two-layer structure in which a fiber-containing layer 20 is laminated on one side of the metal sheet 30, or a two-layer structure in which a silicone foam layer 40 is laminated on one side of the metal sheet 30, may also be used. [Example]

[0035] EXAMPLES The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited to these.

[0036] Laminate evaluation samples were produced using the layer structure and materials shown in Table 1. For the silicone foam, the silicone foam raw material was applied directly to a SUS plate, and then foamed and cured to form an integrated mold. For the fire-resistant paper, the paper was laminated onto the SUS plate via a fusion net (a net-like material formed by crossing polyethylene fibrous material into a mesh), and then bonded at a temperature above the melting point of the fusion net material. Details of the materials listed in Table 1 are as follows: Non-combustible paper: Awa Paper Co., Ltd., I-30HPI SUS plate: SUS304 Silicone foam: NanNex TL7404 (density 380 kg / m) manufactured by Inoac Corporation 3 ) Hard mica: Okabe Mica Co., Ltd., D581 Silica cloth: NSC-1100 manufactured by Nippon Glass Fiber Industry Co., Ltd.

[0037] <Fire resistance / insulation test> The center of a 100mm square evaluation sample was burned using an alcohol lamp (approximately 1000°C), and the surface temperature of the center of the evaluation sample (the surface opposite the flame contact area) was measured after 5 or 10 minutes using a thermocouple. The thermocouple was placed so that it was in contact with the center of the back surface of the evaluation sample.

[0038] <Blast resistance test> Using an air blasting machine (MYBLAST (MY-40B) manufactured by Shinto Kogyo Co., Ltd.), the evaluation sample was blasted for 2 minutes, and the time until penetration was measured. The test conditions for the blast resistance test are as follows. Projection pressure: 0.42 MPa Projection material: Melamine resin (average particle size (D50: volume basis) 500 μm) Nozzle diameter: φ8mm Distance from nozzle outlet to evaluation sample surface: 250 mm

[0039] <Follow-up ability> A 100 mm square evaluation sample is wrapped around a cylindrical polyethylene rod (φ32.5 mm) and made one full turn. ○: If the wrapping was successful ×: If it cannot be wrapped

[0040] [Table 1] [Industrial Applicability]

[0041] The laminate of the present disclosure not only has fire resistance and heat insulation properties but also excellent strength, and therefore can be suitably installed as a protective member in a case that houses an electricity storage device such as a lithium ion battery or an electric double layer capacitor. [Explanation of symbols]

[0042] 10 laminate, 20 fiber-containing layer, 30 metal sheet, 40 silicone foam layer

Claims

1. A laminate comprising a metal sheet and a fiber-containing layer and / or a silicone foam layer laminated to the metal sheet.

2. The laminate according to claim 1 , wherein the fiber-containing layer, the metal sheet, and the silicone foam layer are laminated in this order.

3. 3. The laminate according to claim 1, wherein the thickness of the metal sheet is 500 μm or less.

4. 3. The laminate according to claim 1, wherein the material of the metal sheets is stainless steel.

5. An electricity storage device comprising the laminate according to claim 1 or 2.

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