Film for all-solid-state battery and all-solid-state battery

Abstract

To provide a film for all-solid-state batteries having low density, high elasticity, and low water vapor permeability, and an all-solid-state battery having the film for all-solid-state batteries.SOLUTION: A film 14 for all-solid-state batteries stores an all-solid-state battery element 12 in a sealed state, and is a single-layer film containing 50 mass% or more of thermoplastic elastomer relative to the total amount of 100 mass% of the film for all-solid-state batteries.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a film for an all-solid-state battery and an all-solid-state battery. [Background technology]

[0002] All-solid-state battery films laminated with all-solid-state battery elements are known. All-solid-state electronic elements are configured with an electrolyte layer sandwiched between positive and negative electrode layers, and the electrolyte layer and electrode layers must be in close contact to function as a battery. Therefore, all-solid-state batteries in which all-solid-state electronic elements are laminated with all-solid-state battery films are subjected to a compressive force that maintains the all-solid-state electronic elements in an appropriate state of contact. When installed in devices requiring high power, such as electric vehicles, multiple all-solid-state electronic elements are used, and laminated all-solid-state batteries are used stacked in the thickness direction. As an all-solid-state battery film used in such laminated all-solid-state batteries, a multi-layer aluminum laminate film including a high-density aluminum layer is known. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-167925 Summary of the Invention [Problem to be solved by the invention]

[0004] However, conventionally used aluminum layer films have low elasticity, and there was a concern that laminating an all-solid-state battery element using an aluminum layer film would prevent uniform compression of the entire all-solid-state battery element. Furthermore, sandwiching a rubber sheet or the like between the elements to achieve uniform compression could result in increased weight and space. Furthermore, all-solid-state batteries constructed by laminating an all-solid-state battery element with an all-solid-state battery film have recently been used in devices such as personal digital assistants (PDAs), portable electronic devices, motorcycles, electric vehicles, and hybrid electric vehicles, and may require low density, high elasticity, and low water vapor permeability. However, conventional technologies have used films containing high-density aluminum layers, and no attempt has been made to achieve low density, high elasticity, and low water vapor permeability.

[0005] An object of the present invention is to provide a film for an all-solid-state battery having low density, high elasticity, and low water vapor permeability, and an all-solid-state battery including the film for an all-solid-state battery. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the object, the film for an all-solid-state battery of the present invention is a film for an all-solid-state battery for housing an all-solid-state battery element in a sealed state, and is a single-layer film containing 50% by mass or more of a thermoplastic elastomer relative to 100% by mass of the total amount of the film for the all-solid-state battery. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a film for an all-solid-state battery having low density, high elasticity, and low water vapor permeability, and an all-solid-state battery including the film for an all-solid-state battery. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram of an example of an all-solid-state battery. [Figure 2] FIG. 2 is a schematic diagram of an example of an all-solid-state battery. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of a film for an all-solid-state battery and an all-solid-state battery according to the present invention will be described in detail with reference to the accompanying drawings.

[0010] The film for an all-solid-state battery of this embodiment is a film for an all-solid-state battery for housing an all-solid-state battery element in a sealed state, and is a single-layer film containing 50% by mass or more of a thermoplastic elastomer relative to 100% by mass of the total amount of the film for an all-solid-state battery.

[0011] The film for an all-solid-state battery of this embodiment is a single-layer film containing a thermoplastic elastomer, and therefore can achieve lower density and higher elasticity than films having a multi-layer structure containing aluminum or an aluminum layer. Furthermore, because the film for an all-solid-state battery of this embodiment is a single-layer film containing a thermoplastic elastomer, it can achieve low water vapor permeability comparable to that of aluminum, despite being a film that does not use aluminum.

[0012] Therefore, it is possible to provide a film for an all-solid-state battery having low density, high elasticity, and low water vapor permeability, and an all-solid-state battery including the film for an all-solid-state battery.

[0013] Thermoplastic elastomers have excellent elasticity. Therefore, when an all-solid-state battery film contains a thermoplastic elastomer as a main component, the sealing of the all-solid-state battery housed inside the all-solid-state battery film can be improved. Thermoplastic elastomers also have low volume resistivity and excellent insulating properties. Therefore, all-solid-state battery elements sealed with an all-solid-state battery film containing a thermoplastic elastomer as a main component can be suitably applied to various electronic devices.

[0014] Furthermore, since the film for an all-solid-state battery of this embodiment can achieve high elasticity, laminating an all-solid-state electronic element with the film for an all-solid-state battery makes it possible to apply a compressive force to the all-solid-state electronic element that can maintain an appropriate and uniform adhesion state.

[0015] Furthermore, the film for an all-solid-state battery of this embodiment does not require a rubber sheet or the like to be sandwiched therebetween, and furthermore, can achieve low density, so that it is possible to suppress an increase in the weight and space of the all-solid-state battery, and also to reduce the weight of the film for an all-solid-state battery itself.

[0016] The film for an all-solid-state battery and the all-solid-state battery of this embodiment will be described in detail below.

[0017] 1 and 2 are schematic diagrams showing an example of an all-solid-state battery 10 of this embodiment. Fig. 1 is a schematic plan view of the all-solid-state battery 10. Fig. 2 is a schematic diagram of the A-A' cross section of Fig. 1 viewed from a direction intersecting the cross section.

[0018] (All-solid-state battery) The all-solid-state battery 10 includes an all-solid-state battery element 12 and a film 14 for an all-solid-state battery.

[0019] (All-solid-state battery element) The all-solid-state battery element 12 includes an electrolyte layer 12A, a positive electrode active material layer 12B1, a negative electrode active material layer 12B2, a positive electrode current collector layer 12C1, and a negative electrode current collector layer 12C2. The all-solid-state battery element 12 is a laminate obtained by laminating the negative electrode current collector layer 12C2, the negative electrode active material layer 12B2, the electrolyte layer 12A, the positive electrode active material layer 12B1, and the positive electrode current collector layer 12C1 in this order.

[0020] (electrolyte layer) The electrolyte layer 12A is a layer containing ions that serve as charge carriers, and is disposed between the positive electrode active material layer 12B1 and the negative electrode active material layer 12B2. The electrolyte layer 12A provides ion conduction between the positive electrode active material and the negative electrode active material via the electrolyte contained in the electrolyte layer 12A.

[0021] The electrolyte layer 12A is a solid electrolyte layer.

[0022] The solid electrolyte layer is a layer made of a solid electrolyte material. Examples of solid electrolyte materials include oxide solid electrolyte materials, sulfide solid electrolyte materials, and alkali metal electrolyte materials, with sulfide solid electrolyte materials being preferred. This is because they have high Li-ion conductivity and can provide a high-output all-solid-state battery. The sulfide solid electrolyte material is not particularly limited as long as it contains Li and S and has Li-ion conductivity, but examples include those containing Li, S, and a third component A. Examples of the third component A include at least one selected from the group consisting of P, Ge, B, Si, I, Al, Ga, and As.

[0023] In particular, in the present invention, the sulfide solid electrolyte material is preferably a compound using Li2S and a sulfide MS other than Li2S. Specific examples include a Li2S-P2S5 compound, a Li2S-SiS2 compound, and a Li2S-GeS2 compound, among which a Li2S-P2S5 compound is preferred. This is because it has high Li-ion conductivity. The sulfide solid electrolyte material may be amorphous or crystalline. The average particle size of the solid electrolyte material is, for example, in the range of 1 nm to 100 μm, preferably in the range of 10 nm to 30 μm. An all-solid-state battery 10 using a solid electrolyte layer as the electrolyte layer 12A is sometimes referred to as an all-solid-state battery.

[0024] Examples of alkali metal electrolyte materials include lithium salts, potassium salts, and sodium salts.

[0025] The shape of the electrolyte layer 12A is not limited, but in this embodiment, a form in which the electrolyte layer 12A has a substantially rectangular flat plate shape will be described as an example.

[0026] The thickness of the electrolyte layer 12A is not limited and varies depending on the configuration of the all-solid-state battery element 12. The thickness of the electrolyte layer 12A is, for example, in the range of 0.1 μm to 1000 μm, and preferably in the range of 0.1 μm to 300 μm.

[0027] (Cathode active material layer) One end face of the positive electrode active material layer 12B1 in the thickness direction is disposed in contact with the electrolyte layer 12A, and the other end face is disposed in contact with the positive electrode current collector layer 12C1.

[0028] The positive electrode active material layer 12B1 is a layer containing a positive electrode active material. The positive electrode active material layer 12B1 may contain at least one of a conductive material, a binder, and a solid electrolyte material, as necessary. The positive electrode active material may be a material used as a positive electrode active material in the field of all-solid-state batteries, such as a sulfide-based or oxide-based positive electrode active material. Examples of sulfide-based materials include titanium sulfide (TiS2), molybdenum sulfide (MoS2), iron sulfide (FeS, FeS2), copper sulfide (CuS), and nickel sulfide (Ni3S2). TiS2 is preferably used. Examples of oxide-based materials include bismuth oxide (Bi2O3), bismuth lead oxide (Bi2Pb2O5), copper oxide (CuO), and vanadium oxide (VO 13 ), lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), lithium manganese oxide (LiMnO2), etc. Preferably, lithium cobalt oxide is used. These may also be used in combination.

[0029] The thickness of the positive electrode active material layer 12B1 is not limited and varies depending on the configuration of the all-solid-state battery element 12. The thickness of the positive electrode active material layer 12B1 is preferably within the range of, for example, 1.0 μm to 1000 μm.

[0030] (Negative electrode active material layer) One end face of the negative electrode active material layer 12B2 in the thickness direction is disposed in contact with the electrolyte layer 12A, and the other end face is disposed in contact with the negative electrode current collector layer 12C2.

[0031] The negative electrode active material layer 12B2 is a layer containing a negative electrode active material, and may contain at least one of a conductive material, a binder, and a solid electrolyte material, as necessary.

[0032] As the negative electrode active material, those used as negative electrode active materials in the field of all-solid-state batteries can be used. Examples of the negative electrode active material include metal active materials and carbon active materials. Examples of metal active materials include In, Al, Si, and Sn. On the other hand, examples of carbon active materials include mesocarbon microbeads (MCMB), highly oriented graphite (HOPG), hard carbon, and soft carbon. The shape of the negative electrode active material may be, for example, a film or particulate. In the former case, the negative electrode active material itself usually becomes the negative electrode active material layer. The average particle size of the particulate negative electrode active material is, for example, in the range of 1 nm to 100 μm, preferably in the range of 10 nm to 30 μm. Furthermore, the specific surface area of ​​the particulate negative electrode active material is, for example, 0.1 m 2 / g~10m 2 It is preferable that the saturation temperature is in the range of / g.

[0033] (Positive electrode current collector layer) The positive electrode current collector layer 12C1 is a layer that collects current from the positive electrode active material layer 12B1. The positive electrode current collector layer 12C1 is disposed in contact with one of both end surfaces in the thickness direction of the positive electrode active material layer 12B1, on the side opposite to the surface that comes into contact with the electrolyte layer 12A.

[0034] The positive electrode current collector layer 12C1 is made of, for example, copper, magnesium, stainless steel, titanium, iron, cobalt, nickel, zinc, aluminum, germanium, indium, lithium, or an alloy thereof.

[0035] A region of the positive electrode current collector layer 12C1 that protrudes from a region obtained by orthogonally projecting the electrolyte layer 12A onto the positive electrode current collector layer 12C1 in the thickness direction is configured as a thin, elongated positive electrode terminal T1. The positive electrode terminal T1 is configured, for example, by press-molding integrally with the positive electrode current collector layer 12C1.

[0036] (negative electrode current collector layer) The negative electrode current collector layer 12C2 is a layer that collects current from the negative electrode active material layer 12B2. The negative electrode current collector layer 12C2 is disposed in contact with one of both end surfaces in the thickness direction of the negative electrode active material layer 12B2, on the side opposite to the surface in contact with the electrolyte layer 12A.

[0037] The negative electrode current collector layer 12C2 is made of, for example, copper, magnesium, stainless steel, titanium, iron, cobalt, nickel, zinc, aluminum, germanium, indium, lithium, or an alloy thereof.

[0038] A region of the negative electrode current collector layer 12C2 that protrudes from a region obtained by orthogonally projecting the electrolyte layer 12A onto the negative electrode current collector layer 12C2 in the thickness direction is configured as a thin, elongated negative electrode terminal T2. The negative electrode terminal T2 is configured, for example, by press-molding integrally with the negative electrode current collector layer 12C2.

[0039] (Film for all-solid-state batteries) The all-solid-state battery film 14 is a film for housing the all-solid-state battery element 12 in a sealed state.

[0040] The film 14 for an all-solid-state battery is a single-layer film containing a thermoplastic elastomer.

[0041] (thermoplastic elastomer) The type of thermoplastic elastomer contained in the film 14 for an all-solid-state battery is not particularly limited.

[0042] The water vapor permeability of the thermoplastic elastomer contained in the film for all-solid-state batteries 14 is set to 0.34 g·mm / (m 2 ·day) or less is preferable, and 0.30g·mm / (m 2 ·day) or less is more preferable, and 0.25g·mm / (m 2 ·day) or less is more preferable, and 0.20g·mm / (m 2 ·day) or less is particularly preferred.

[0043] Water vapor permeability can be measured using a GTR-30XATK (GTR Tech) at a temperature of 40°C and a relative humidity of 90% in accordance with JIS K7129 (Annex C, 2008) using an evaluation test piece made of thermoplastic elastomer, measuring 70 mm long x 70 mm wide x 30 μm thick. The lower the water vapor permeability value, the better the water vapor barrier properties.

[0044] For example, it is desirable to use one or more types of thermoplastic elastomer selected from an olefin-based thermoplastic elastomer and a styrene-based thermoplastic elastomer. Olefin-based and styrene-based thermoplastic elastomers are preferred because they are highly durable against water and acids such as hydrofluoric acid, and also because they extract less impurities that affect the all-solid-state battery 10.

[0045] Examples of olefin-based thermoplastic elastomers include those obtained by dynamically crosslinking an olefin-based copolymer rubber such as ethylene-propylene copolymer rubber or ethylene-propylene-diene copolymer rubber (EPDM) with an olefin-based resin such as a propylene-based resin or an ethylene-based resin.

[0046] Examples of styrene-based thermoplastic elastomers include styrene-based block copolymers such as styrene-butadiene block copolymer (SBS), styrene-ethylene / butylene-styrene block copolymer (SEBS), styrene-isoprene-styrene block copolymer (SIS), styrene-isobutylene-styrene copolymer (SIBS), styrene-isobutylene copolymer (SIB), polybutadiene (PB), and styrene-(ethylene-ethylene / propylene)-styrene block copolymer (SEEPS).

[0047] The thermoplastic elastomer contained in the film 14 for an all-solid-state battery may be at least one selected from the group of thermoplastic elastomers listed above.

[0048] Among these, it is preferable to use a styrene-based thermoplastic elastomer as the thermoplastic elastomer contained in the film 14 for an all-solid-state battery from the viewpoints of elasticity and barrier properties against gas or water.

[0049] Furthermore, from the viewpoints of heat aging resistance and gas or water barrier properties, it is preferable to use at least one of a styrene-isoprene-styrene block copolymer (SIS) and a styrene-isobutylene-styrene copolymer (SIBS), and it is particularly preferable to use a styrene-isobutylene-styrene copolymer (SIBS) as the styrene-based thermoplastic elastomer.

[0050] The mass average molecular weight, styrene content, and softening point of each of the styrene-isoprene-styrene block copolymer (SIS) and the styrene-isobutylene-styrene copolymer (SIBS) contained in the all-solid-state battery film 14 are not limited.

[0051] Specific examples of commercially available thermoplastic elastomers used in the all-solid-state battery film 14 include SIBSTAR103T (manufactured by Kaneka Corporation), SIBSTAR062T (manufactured by Kaneka Corporation), SIBSTAR073T (manufactured by Kaneka Corporation), and Clarity Examples of such polyurethanes include LA2250 (manufactured by Kuraray Co., Ltd.), Quintac (registered trademark) 3290 (manufactured by Zeon Corporation), Quintac 3440 (manufactured by Zeon Corporation), ES-A60NX (manufactured by Aronkasei Co., Ltd.), AR-1060 (manufactured by Aronkasei Co., Ltd.), AR-8070 (manufactured by Aronkasei Co., Ltd.), T-A80NT (manufactured by Aronkasei Co., Ltd.), T-A90NT (manufactured by Aronkasei Co., Ltd.), VF-A40NT-B1 (manufactured by Aronkasei Co., Ltd.), VF-A50NT-B1 (manufactured by Aronkasei Co., Ltd.), VF-A60NT-B1 (manufactured by Aronkasei Co., Ltd.), VF-A70NT-B1 (manufactured by Aronkasei Co., Ltd.), VF-A80NT-B1 (manufactured by Aronkasei Co., Ltd.), and VF-A90NT-B1 (manufactured by Aronkasei Co., Ltd.).

[0052] As described above, the content of the thermoplastic elastomer in the film 14 for an all-solid-state battery is preferably 50% by mass or more, indicating that it is a main component, relative to 100% by mass of the entire film 14 for an all-solid-state battery. Furthermore, the content of the thermoplastic elastomer in the film 14 for an all-solid-state battery is more preferably 65% ​​by mass or more, and particularly preferably 75% by mass or more, relative to 100% by mass of the entire film 14 for an all-solid-state battery. By setting the content of the thermoplastic elastomer in the film 14 for an all-solid-state battery within the above range, the effects of water vapor barrier properties and high compression set can be obtained.

[0053] The thermoplastic elastomer may be acid-modified. Here, "acid" refers to an acid component such as acid, acid anhydride, acid ester, or metallocene. The acid-modified portion of the thermoplastic elastomer contributes to adhesiveness.

[0054] (tackifier) The film 14 for an all-solid-state battery preferably further contains a tackifier.

[0055] Any appropriate tackifier can be used as the tackifier, such as a tackifying resin. Specific examples of tackifying resins include rosin-based tackifying resins (e.g., unmodified rosin, modified rosin, rosin phenolic resins, rosin ester resins, etc.), terpene-based tackifying resins (e.g., terpene resins, terpene phenolic resins, styrene-modified terpene resins, aromatic-modified terpene resins, hydrogenated terpene 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.

[0056] Specific examples of commercially available tackifiers contained in the all-solid-state battery film 14 include T-REZ OP501 (manufactured by ENEOS Corporation), T-REZ HA125 (manufactured by ENEOS Corporation), and Quintone G115 (manufactured by Zeon Corporation).

[0057] The content of the tackifier in the film 14 for an all-solid-state battery is preferably 0% by mass or more and 40% by mass or less, more preferably 1% by mass or more and 30% by mass or less, and particularly preferably 4% by mass or more and 20% by mass or less, relative to 100% by mass of the entire film 14 for an all-solid-state battery.

[0058] When the all-solid-state battery film 14 contains a tackifier within the above range relative to 100% by mass of the entire all-solid-state battery film 14, the effect of fastening the electrolyte layer can be obtained.

[0059] (anti-aging agent) The all-solid-state battery film 14 may further contain an antioxidant. It is believed that the all-solid-state battery film 14 further containing an antioxidant can provide the effect of improving weather resistance and heat resistance.

[0060] As the antioxidant contained in the film 14 for an all-solid-state battery, any appropriate antioxidant can be used.

[0061] Examples of the antioxidant include phenol-based antioxidants, amine-based antioxidants, phosphorus-based antioxidants, and sulfur-based antioxidants.

[0062] Examples of commercially available antioxidants include Nonflex Alba (manufactured by Seiko Chemical Co., Ltd.) and Suntite S (manufactured by Seiko Chemical Co., Ltd.).

[0063] (Other ingredients) The all-solid-state battery film 14 may contain any appropriate additives as needed. Examples of such additives include plasticizers, softeners, antioxidants, processing aids, waxes, and fillers. Examples of fillers include alumina, silicon nitride, boron nitride, and aluminum nitride silica. By further including a filler, the thermal conductivity and strength of the all-solid-state battery film 14 can be improved.

[0064] (Manufacturing method of all-solid-state batteries) Next, an example of a method for manufacturing the all-solid-state battery 10 including the film 14 for the all-solid-state battery will be described.

[0065] First, a laminate obtained by laminating the negative electrode current collector layer 12C2, the negative electrode active material layer 12B2, the electrolyte layer 12A, the positive electrode active material layer 12B1, and the positive electrode current collector layer 12C1 in this order is prepared as the all-solid-state battery element 12. A known method may be used to manufacture the all-solid-state battery element 12. In addition, in this embodiment, the all-solid-state battery element 12 will be described assuming a form in which the cross section is a rectangular parallelepiped.

[0066] Then, a pair of flat, rectangular films 14 for an all-solid-state battery are placed one on top of the other. Three of the four sides of the rectangular films 14 for an all-solid-state battery that form a rectangle along the periphery of the pair of rectangular films 14 for an all-solid-state battery are heat-sealed to form a bag-like shape welded by the heat-sealing portion 13B (see also FIGS. 1 and 2). The bag-shaped film 14 for an all-solid-state battery has three of the four sides welded along the periphery of the rectangle, with one side serving as an open end. The all-solid-state battery element 12 is inserted and housed so that the positive electrode terminal T1 and the negative electrode terminal T2 protrude from the open end of the film 14 for an all-solid-state battery. The open end is then welded by heat welding. The film 14 for an all-solid-state battery and the surfaces of the positive electrode terminal T1 and the negative electrode terminal T2 facing the film 14 for an all-solid-state battery are bonded together by an adhesive or the like. Through these steps, the opening edge is welded by the fusion portion 13A, and the all-solid-state battery element 12 is housed between the pair of films 14 for an all-solid-state battery in a sealed state.

[0067] Then, in order to improve the adhesion between adjacent layers of the negative electrode current collector layer 12C2, the negative electrode active material layer 12B2, the electrolyte layer 12A, the positive electrode active material layer 12B1, and the negative electrode current collector layer 12C2 that constitute the all-solid-state battery element 12, the all-solid-state battery film 14 that houses the all-solid-state battery element 12 is pressed from the outside in the thickness direction of each layer that constitutes the all-solid-state battery element 12.

[0068] Through these processes, the all-solid-state battery 10 is manufactured.

[0069] Here, thermoplastic elastomers have excellent elasticity, and therefore, when the all-solid-state battery film 14 contains a thermoplastic elastomer, even if pressure is applied from the outside of the all-solid-state battery film 14, which has been formed into a bag shape during the production of the all-solid-state battery 10, the elasticity of the all-solid-state battery film 14 can prevent cracking or damage to each layer, such as the electrolyte layer 12A, which constitutes the all-solid-state battery element 12 arranged inside.

[0070] Furthermore, since the all-solid-state battery film 14 contains a thermoplastic elastomer as a main component, it is possible to continue to ensure the installation area of ​​the all-solid-state battery element 12 housed inside by the elastic force of the all-solid-state battery film 14 during the manufacture of the all-solid-state battery 10, without complicating the pressurizing mechanism.

[0071] Furthermore, since the all-solid-state battery film 14 contains a thermoplastic elastomer as a main component, the all-solid-state battery element 12 can be suitably housed in a sealed state inside the bag-shaped all-solid-state battery film 14 by applying pressure from the outside of the bag-shaped all-solid-state battery film 14 without drawing a vacuum inside the all-solid-state battery film 14 during production of the all-solid-state battery 10.

[0072] (Applicable to all-solid-state batteries) The all-solid-state battery 10 of this embodiment is suitably applied as an all-solid-state battery used in electronic devices such as electric vehicles, hybrid electric vehicles, motorcycles powered by motors or the like, personal digital assistants, portable electronic devices, and small-sized home power storage devices.

[0073] One of the requirements for all-solid-state batteries to be installed in these electronic devices is weight reduction. The all-solid-state battery film 14 constituting the all-solid-state battery 10 of this embodiment is a single-layer film including the all-solid-state battery film 14, and therefore can achieve lower density, i.e., weight reduction, compared to conventional films that use aluminum laminate films or multilayer films in which an aluminum layer is sandwiched between a pair of resin layers. Therefore, the all-solid-state battery 10 of this embodiment can be suitably applied to these electronic devices.

[0074] Furthermore, the all-solid-state battery film 14 constituting the all-solid-state battery 10 of this embodiment contains an insulating thermoplastic elastomer, and therefore can also function as an insulating film. Therefore, the all-solid-state battery 10 of this embodiment can be suitably applied to the above-mentioned electronic devices.

[0075] Furthermore, since the all-solid-state battery film 14 constituting the all-solid-state battery 10 of this embodiment is a single-layer film, the all-solid-state battery 10 can be made smaller than when a film with a multi-layer configuration is used.

[0076] Furthermore, since the all-solid-state battery film 14 constituting the all-solid-state battery 10 of this embodiment contains a thermoplastic elastomer, when the electrolyte layer 12A of the all-solid-state battery element 12 is a solid electrolyte layer, part of the pressure caused by pressurization during the production of the all-solid-state battery 10 is absorbed by the all-solid-state battery film 14, and it is possible to suppress cracking or damage to the electrolyte layer 12A. [Example]

[0077] The present invention will be specifically explained below with reference to examples, but the present invention is not limited to these examples.

[0078] Test pieces having the following all-solid-state battery film 14 and comparative all-solid-state battery film were prepared, and the adhesive strength of these test pieces was evaluated.

[0079] -Preparation of test specimens- For the all-solid-state battery film 14 and the comparative all-solid-state battery film, raw materials were prepared with the compositions shown in Tables 1 and 2. The compositions in Tables 1 and 2 show the content relative to the all-solid-state battery film 14, with the entire all-solid-state battery film 14 being taken as 100 mass %.

[0080] Raw materials having the compositions shown in Tables 1 and 2 were mixed for 1 minute in a Henschel mixer. Next, the resulting mixture was fed into the feed port of a co-rotating twin-screw kneading extruder (cylinder diameter 32 mm, L / D=56) equipped with a raw material feed port, dynamically heat-treated by melt-kneading at 180°C, and extrusion-molded into a sheet having a thickness of 200 μm, thereby obtaining films 14 for all-solid-state batteries and comparative films for all-solid-state batteries of Examples 1 to 11 and Comparative Examples 1 to 6. For the comparative film for all-solid-state batteries of Comparative Example 7, an exterior laminate film consisting of a substrate layer, a first adhesive layer, a barrier layer (aluminum foil), a second adhesive layer, and a sealant layer was used.

[0081] <Density evaluation> The density of each of the test pieces of the films 14 for all-solid-state batteries of Examples 1 to 11 and the test pieces of the comparative films for all-solid-state batteries of Comparative Examples 1 to 7 was measured. The density was measured by the density gradient tube method (23°C) in accordance with JIS K7112:1999. The measurement was carried out within 8 hours after the test pieces were prepared. The measurement results are shown in Tables 1 and 2.

[0082] <Insulation evaluation> The insulating properties were evaluated by measuring the volume resistivity of each of the test pieces of the films 14 for all-solid-state batteries of Examples 1 to 11 and the test pieces of the comparative films for all-solid-state batteries of Comparative Examples 1 to 7. The volume resistivity was measured in accordance with JIS K7194. The measurement results are shown in Tables 1 and 2.

[0083] <Elasticity evaluation> Elasticity was evaluated by measuring the compression set of each of the test pieces of the films 14 for all-solid-state batteries in Examples 1 to 11, and the test pieces of the films for comparative all-solid-state batteries in Comparative Examples 1 to 7. The compression set was measured in accordance with JIS K6262 under conditions of 23°C x 24 hours and a compression ratio of 25%. The measurement results are shown in Tables 1 and 2.

[0084] [Table 1]

[0085] [Table 2]

[0086] As shown in Tables 1 and 2, it was confirmed that the films 14 for all-solid-state batteries in Examples 1 to 11 had lower density and were lighter in weight than the comparative films for all-solid-state batteries in the comparative examples.

[0087] It was also confirmed that the films 14 for all-solid-state batteries of Examples 1 to 11 had excellent insulating properties. It was also confirmed that the films 14 for all-solid-state batteries of Examples 1 to 11 had excellent elasticity compared to the comparative films for all-solid-state batteries of the Comparative Examples and Reference Examples. It was also confirmed that the films 14 for all-solid-state batteries of Examples 1 to 11 had low water vapor permeability equivalent to that of the aluminum laminate shown in Comparative Example 7.

[0088] That is, it was confirmed that the films 14 for all-solid-state batteries of Examples 1 to 11 achieved all of low density, high elasticity, and low water vapor permeability compared to the comparative films for all-solid-state batteries of Comparative Examples.

[0089] It should be noted that the various materials and compositions used in the above examples are merely examples, and the present invention is not limited thereto. Furthermore, the specific structure of the all-solid-state battery 10 is not limited to those exemplified in FIGS. 1 and 2. [Explanation of symbols]

[0090] 10 All-solid-state battery 12 All-solid-state battery element 14 Film for solid-state batteries

Claims

1. A film for an all-solid-state battery for housing an all-solid-state battery element in a sealed state, The film for the all-solid-state battery is a single-layer film containing 50% by mass or more of a thermoplastic elastomer with respect to a total amount (100% by mass) of the film. Film for solid-state batteries.

2. The water vapor permeability of the thermoplastic elastomer is 0.34 g mm / (m ２ ・day) or less, The film for an all-solid-state battery according to claim 1 .

3. The thermoplastic elastomer is a styrene-isobutylene-styrene type block copolymer (SIBS). The film for an all-solid-state battery according to claim 1 .

4. Further comprising a tackifier, The film for an all-solid-state battery according to claim 1 .

5. Further comprising an antioxidant, The film for an all-solid-state battery according to claim 1 .

6. further comprising a filler, The film for an all-solid-state battery according to claim 1 .

7. the all-solid-state battery element includes an electrolyte layer, the electrolyte layer is a solid electrolyte layer made using an alkali metal-based electrolyte material; The film for an all-solid-state battery according to claim 1 .

8. an all-solid-state battery element; The film for an all-solid-state battery according to claim 1; An all-solid-state battery comprising:

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