Exterior material for all-solid-state battery and all-solid-state battery using the same

Abstract

An exterior material for an all-solid-state battery containing a sulfide-based solid electrolyte, the exterior material having at least a substrate layer, a barrier layer, and a sealant layer in this order, wherein the sealant layer contains an ionomer.

Description

Technical Field

[0001] The present disclosure relates to an exterior material for an all-solid-state battery and an all-solid-state battery using the same, and more particularly, to an exterior material for an all-solid-state battery containing a sulfide-based solid electrolyte and an all-solid-state battery using the same.

Background Art

[0002] Secondary batteries such as lithium-ion batteries are widely used in portable electronic devices, electric vehicles powered by electricity, and hybrid electric vehicles. As a battery with improved safety of lithium-ion batteries, an all-solid-state lithium battery using an inorganic solid electrolyte instead of an organic solvent electrolyte has been studied. The all-solid-state lithium battery is superior in safety to the lithium-ion battery in that thermal runaway due to short circuit or the like is less likely to occur.

[0003] Among inorganic solid electrolytes, sulfide-based solid electrolytes have a higher ionic conductivity than oxide-based solid electrolytes and have many advantages in obtaining a higher-performance all-solid-state battery. However, since the all-solid-state battery using a sulfide-based solid electrolyte contains sulfur, there is a possibility that moisture entering the battery reacts with sulfur to generate toxic hydrogen sulfide. Therefore, when the exterior material of the battery is damaged, there is a concern that this hydrogen sulfide may leak out. In order to prevent the leakage of hydrogen sulfide, for example, Patent Documents 1 and 2 propose all-solid-state batteries with a safety design that captures and detoxifies the generated hydrogen sulfide.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the methods described in Patent Documents 1 and 2 have a problem in that a very large amount of labor and effort is required for manufacturing a battery, which may cause a significant cost increase. Further, since hydrogen sulfide is corrosive, there is a concern that it may corrode copper foil or aluminum foil which is a current collector and lead to deterioration of the battery. However, in the inventions described in Patent Documents 1 and 2, no consideration has been given from the viewpoint of suppressing corrosion by hydrogen sulfide.

[0006] An object of the present disclosure is to provide an exterior material for an all-solid-state battery including a sulfide-based solid electrolyte, which can detoxify hydrogen sulfide when generated and can suppress corrosion of a current collector, and an all-solid-state battery using the same.

Means for Solving the Problems

[0007] As materials capable of detoxifying hydrogen sulfide, alkali metals and alkaline earth metals are known. As a method of using these materials, a method such as coating a layer containing these materials can be mentioned. However, when a layer containing the above materials is coated on the exterior material, it becomes difficult to perform heat sealing like a conventional laminate film. Therefore, methods such as forming a layer containing the above materials so as to cover the electrode member in advance or forming it around the exterior material are required. When forming a layer containing the above materials around the exterior material, it is necessary to provide a layer containing the above materials after drawing molding. This is to prevent these problems from occurring during drawing molding because the layer containing the above materials is likely to crack or peel. When these methods are adopted, a very large amount of labor and effort is required for manufacturing the battery.

[0008] On the other hand, a method of dispersing an alkali metal or an alkaline earth metal in a sealant layer is also conceivable. However, in this case, the resin for forming the sealant layer and the alkali metal etc. have extremely poor miscibility, and a sealant layer made of a material in which they are mixed becomes very brittle, and there are problems such as a decrease in seal strength.

[0009] In view of the above circumstances, as a result of intensive research by the present inventors, by using an ionic polymer material such as an olefin-metal ion compound called an ionomer, hydrogen sulfide can be detoxified, and an exterior material having characteristics equivalent to those of a conventional exterior material has been completed.

[0010] That is, the present disclosure provides an exterior material for an all-solid-state battery containing a sulfide-based solid electrolyte, which includes at least a base material layer, a barrier layer, and a sealant layer in this order, and the sealant layer contains an ionomer.

[0011] According to the above exterior material for an all-solid-state battery, when hydrogen sulfide is generated inside the exterior material in an all-solid-state battery using the exterior material, the ionomer in the sealant layer disposed on the inner side of the exterior material rather than the barrier layer can detoxify hydrogen sulfide, and corrosion of the current collector inside the exterior material can be suppressed. The reason why the ionomer can detoxify hydrogen sulfide is that the metal ions forming the ionomer react with hydrogen sulfide and hydrogen sulfide changes into metal sulfide. Thereby, deterioration of the all-solid-state battery can be suppressed. Further, since the ionomer detoxifies hydrogen sulfide, even when the exterior material of the all-solid-state battery is broken, leakage of hydrogen sulfide can be suppressed. Therefore, by using the above exterior material for an all-solid-state battery, an all-solid-state battery with higher safety can be provided. Furthermore, the above exterior material can be manufactured by the same method as the conventional one without going through a special process, and since the exterior material itself has a function of detoxifying hydrogen sulfide, it is also possible to manufacture an all-solid-state battery by the same method as the conventional one without going through a special process when manufacturing an all-solid-state battery.

[0012] In the above exterior material for an all-solid-state battery, the ionomer may include an ethylene-based ionomer resin.

[0013] In the above-described exterior material for all-solid-state batteries, the metal ions forming the above ionomer may contain zinc ions. Zinc ions have a high reactivity with hydrogen sulfide and can efficiently change hydrogen sulfide into zinc sulfide. Therefore, hydrogen sulfide can be detoxified more quickly and efficiently, and corrosion of the current collector can be further suppressed.

[0014] In the above-described exterior material for all-solid-state batteries, the above sealant layer may include a mixed resin layer containing a polypropylene-based resin and an ethylene-based ionomer resin that is incompatible with the polypropylene-based resin as the above ionomer. Further, the above mixed resin layer may further contain a compatibilizer having a site compatible with the polypropylene-based resin and a site compatible with the ethylene-based ionomer resin. The above mixed resin layer becomes a layer having both high heat sealability and a function of detoxifying hydrogen sulfide at a high level. Since the ethylene-based ionomer is incompatible with the polypropylene-based resin, the above mixed resin layer usually has a sea-island structure in which the ethylene-based ionomer is dispersed in the polypropylene-based resin. By adding the above compatibilizer thereto, the adhesion at the sea-island interface can be enhanced, and the seal strength after heat sealing can be further improved.

[0015] The content of the above ionomer in the above mixed resin layer may be 1 to 40% by mass based on the total solid content of the above mixed resin layer. In this case, the exterior material can achieve both high heat sealability and a function of detoxifying hydrogen sulfide at a higher level.

[0016] In the above-described exterior material for all-solid-state batteries, the above sealant layer may be composed of a plurality of layers, at least one of which is a layer containing the above ionomer and at least one of the other layers is a layer containing a polypropylene-based resin. When the sealant layer has the above structure, the layer containing the ionomer can exhibit a function of detoxifying hydrogen sulfide, and the layer containing the polypropylene-based resin can exhibit excellent heat sealability.

[0017] In the above-described exterior material for an all-solid-state battery, a corrosion prevention treatment layer may be provided on one or both surfaces of the barrier layer. By providing the corrosion prevention treatment layer, corrosion of the barrier layer can be prevented, and the adhesion between the barrier layer and the adjacent layer can be enhanced by the interposition of the corrosion prevention treatment layer.

[0018] In the above-described exterior material for an all-solid-state battery, the corrosion prevention treatment layer may contain cerium oxide, 1 to 100 parts by mass of phosphoric acid or phosphate based on 100 parts by mass of the cerium oxide, and a cationic polymer. According to such an exterior material, it is excellent in resistance to hydrogen sulfide, and corrosion of the barrier layer of the exterior material by hydrogen sulfide can be suppressed. Further, by providing the corrosion prevention treatment layer, the adhesion between the sealant layer and the barrier layer is easily maintained.

[0019] The present disclosure also provides an all-solid-state battery including a battery element containing a sulfide-based solid electrolyte, a current extraction terminal extending from the battery element, and the above-described exterior material for an all-solid-state battery that sandwiches the current extraction terminal and houses the battery element.

Advantages of the Invention

[0020] According to the present disclosure, it is possible to provide an exterior material for an all-solid-state battery containing a sulfide-based solid electrolyte and an all-solid-state battery using the same, which can detoxify hydrogen sulfide when it is generated and suppress corrosion of the current collector.

Brief Description of the Drawings

[0021]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0022] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant descriptions are omitted. Also, the dimensional ratios in the drawings are not limited to the illustrated ratios.

[0023] [Exterior Material for All-Solid-State Battery] FIG. 1 is a cross-sectional view schematically showing an embodiment of the exterior material for an all-solid-state battery of the present embodiment. As shown in FIG. 1, the exterior material (exterior material for all-solid-state battery) 10 of the present embodiment includes a base material layer 11, an adhesive layer 12 (sometimes referred to as the first adhesive layer 12) formed on one surface of the base material layer 11, a barrier layer 13 formed on the surface of the first adhesive layer 12 opposite to the base material layer 11, a corrosion prevention treatment layer 14 formed on the surface of the barrier layer 13 opposite to the first adhesive layer 12, an adhesive layer 17 (sometimes referred to as the second adhesive layer 17) formed on the surface of the corrosion prevention treatment layer 14 opposite to the barrier layer 13, and a sealant layer 16 formed on the surface of the second adhesive layer 17 opposite to the corrosion prevention treatment layer 14, which are sequentially laminated. In the exterior material 10, the base material layer 11 is the outermost layer and the sealant layer 16 is the innermost layer. That is, the exterior material 10 is used with the base material layer 11 facing the outside of the all-solid-state battery and the sealant layer 16 facing the inside of the all-solid-state battery. Hereinafter, each layer will be described.

[0024] [Base Material Layer 11] The base material layer 11 is provided for the purpose of imparting heat resistance in the sealing process during the manufacture of all-solid-state batteries and preventing pinholes that may occur during processing and distribution. It is preferable to use a resin layer having insulation properties. As such a resin layer, for example, a stretched or unstretched film such as a polyester film, a polyamide film, or a polypropylene film can be used as a single-layer or multi-layer film laminated with two or more layers. It is also possible to use a co-extruded multi-layer stretched film obtained by co-extruding a polyethylene terephthalate film (PET) and a nylon film (Ny) using an adhesive resin and then performing a stretching treatment.

[0025] The base material layer 11 may be provided by directly coating it on the barrier layer 13 described later. In this case, the first adhesive layer 12 described later is unnecessary. As a method for forming the base material layer by coating, a method of applying a resin coating solution such as a urethane resin, an acrylic resin, or a polyester resin and curing it by ultraviolet irradiation, high-temperature heating, aging treatment, etc. can be adopted. The coating method is not particularly limited, and various methods such as gravure coating, reverse coating, roll coating, and bar coating can be adopted.

[0026] The thickness of the base material layer 11 is preferably 3 to 40 μm, and more preferably 5 to 25 μm. When the thickness of the base material layer 11 is 3 μm or more, the pinhole resistance and insulation properties of the exterior material 10 for all-solid-state batteries tend to be improved. On the other hand, when the thickness of the base material layer 11 is 40 μm or less, the deep drawing formability of the exterior material 10 for all-solid-state batteries tends to be further improved.

[0027] <The first adhesive layer 12> The first adhesive layer 12 is a layer that adheres the base material layer 11 and the barrier layer 13. Specific examples of the material constituting the first adhesive layer 12 include polyurethane resins obtained by reacting a polyisocyanate compound having two or more functional groups with a main agent such as polyester polyol, polyether polyol, acrylic polyol, or carbonate polyol.

[0028] The above various polyols can be used alone or in combination of two or more kinds according to the functions and performances required for the exterior material.

[0029] Also, according to the performances required for the adhesive, various other additives and stabilizers may be blended into the above-mentioned polyurethane resin.

[0030] The thickness of the first adhesive layer 12 is not particularly limited, but from the viewpoint of obtaining desired adhesive strength, followability, processability, etc., for example, 1 to 10 μm is preferable, and 3 to 7 μm is more preferable.

[0031] <Barrier layer 13> The barrier layer 13 has a water vapor barrier property that prevents moisture from entering the inside of the all-solid-state battery. Also, the barrier layer 13 has ductility for deep drawing molding. As the barrier layer 13, for example, various metal foils such as aluminum, stainless steel, and copper, or metal vapor deposition films, inorganic oxide vapor deposition films, carbon-containing inorganic oxide vapor deposition films, films provided with these vapor deposition films, etc. can be used. As the film provided with a vapor deposition film, for example, an aluminum vapor deposition film and an inorganic oxide vapor deposition film can be used. These can be used alone or in combination of two or more kinds. As the barrier layer 13, a metal foil is preferable, and an aluminum foil is more preferable, from the viewpoints of mass (specific gravity), moisture-proof property, processability, and cost.

[0032] As the aluminum foil, a soft aluminum foil particularly subjected to annealing treatment can be preferably used from the viewpoint of imparting desired ductility during molding. However, for the purpose of further imparting pinhole resistance and ductility during molding, it is more preferable to use an aluminum foil containing iron. The content of iron in the aluminum foil is preferably 0.1 to 9.0% by mass, and more preferably 0.5 to 2.0% by mass, in 100% by mass of the aluminum foil. By the content of iron being 0.1% by mass or more, an exterior material 10 having more excellent pinhole resistance and ductility can be obtained. By the content of iron being 9.0% by mass or less, an exterior material 10 having more excellent flexibility can be obtained.

[0033] The thickness of the barrier layer 13 is not particularly limited, but it is preferably 9 to 200 μm, more preferably 15 to 100 μm, in consideration of barrier properties, pinhole resistance, and processability.

[0034] When using aluminum foil for the barrier layer 13, as the aluminum foil, untreated aluminum foil may be used, but it is preferable to use degreased aluminum foil.

[0035] When degreasing the aluminum foil, the degreasing treatment may be performed on only one side of the aluminum foil, or may be performed on both sides.

[0036] <Corrosion prevention treatment layer 14> The corrosion prevention treatment layer 14 is a layer provided to prevent corrosion of a metal foil (metal foil layer) or the like constituting the barrier layer 13. As the corrosion prevention treatment layer 14, for example, it is formed by degreasing treatment, hot water conversion treatment, anodizing treatment, chemical conversion treatment, or a combination of these treatments.

[0037] Examples of the degreasing treatment include acid degreasing or alkaline degreasing. Examples of acid degreasing include methods using inorganic acids such as sulfuric acid, nitric acid, hydrochloric acid, and hydrofluoric acid alone or a mixed solution thereof. Also, as acid degreasing, by using an acid degreasing agent in which a fluorine-containing compound such as ammonium bifluoride monosodium is dissolved in the above inorganic acid, not only can the degreasing effect of aluminum be obtained, but also a fluoride of aluminum, which is passive, can be formed, which is effective in terms of corrosion resistance, especially when using aluminum foil for the barrier layer 13. Examples of alkaline degreasing include methods using sodium hydroxide or the like.

[0038] Examples of the hot water conversion treatment include boehmite treatment in which aluminum foil is immersed in boiling water added with triethanolamine.

[0039] Examples of the anodizing treatment include alumite treatment.

[0040] Examples of the chemical conversion treatment include immersion type and coating type. Examples of the immersion type chemical conversion treatment include chromate treatment, zirconium treatment, titanium treatment, vanadium treatment, molybdenum treatment, calcium phosphate treatment, strontium hydroxide treatment, cerium treatment, ruthenium treatment, or various chemical conversion treatments composed of a mixed phase thereof. On the other hand, as the coating type chemical conversion treatment, a method of applying a coating agent having corrosion prevention performance on the barrier layer 13 can be mentioned.

[0041] When at least a part of the corrosion prevention treatment layer is formed by any one of the hot water conversion treatment, anodizing treatment, and chemical conversion treatment among these corrosion prevention treatments, it is preferable to perform the degreasing treatment described above in advance. In addition, when using a degreased metal foil such as a metal foil passed through an annealing process as the barrier layer 13, there is no need to perform degreasing treatment again in the formation of the corrosion prevention treatment layer 14.

[0042] The coating agent used for the coating type chemical conversion treatment preferably contains trivalent chromium. Further, the coating agent may contain at least one polymer selected from the group consisting of a cationic polymer and an anionic polymer described later.

[0043] In addition, among the above treatments, particularly in the hot water conversion treatment and anodizing treatment, the surface of the aluminum foil is dissolved by the treatment agent to form an aluminum compound (boehmite, alumite) having excellent corrosion resistance. Therefore, since a co-continuous structure is formed from the barrier layer 13 using the aluminum foil to the corrosion prevention treatment layer 14, the above treatment is included in the definition of the chemical conversion treatment. On the other hand, as will be described later, it is also possible to form the corrosion prevention treatment layer 14 only by a pure coating method that is not included in the definition of the chemical conversion treatment. As this method, for example, a method of using a sol of a rare earth element oxide such as cerium oxide having an average particle size of 100 nm or less, which has an aluminum corrosion prevention effect (inhibitor effect) and is also a suitable material from an environmental aspect, can be mentioned. By using this method, it is possible to impart a corrosion prevention effect to a metal foil such as an aluminum foil even by a general coating method.

[0044] Examples of the sol of the rare earth element oxide include sols using various solvents such as aqueous, alcohol, hydrocarbon, ketone, ester, and ether solvents. Among them, an aqueous sol is preferred.

[0045] In the sol of the rare earth element oxide, inorganic acids such as nitric acid, hydrochloric acid, and phosphoric acid or their salts, and organic acids such as acetic acid, malic acid, ascorbic acid, and lactic acid are usually used as dispersion stabilizers to stabilize the dispersion. Among these dispersion stabilizers, phosphoric acid in particular is expected to (1) stabilize the dispersion of the sol, (2) improve the adhesion to the barrier layer 13 by utilizing the aluminum chelating ability of phosphoric acid, and (3) improve the cohesive force of the corrosion prevention treatment layer 14 (oxide layer) due to the easy occurrence of dehydration condensation of phosphoric acid even at low temperatures in the exterior material 10.

[0046] Examples of the phosphoric acid or its salt include orthophosphoric acid, pyrophosphoric acid, metaphosphoric acid, or their alkali metal salts and ammonium salts. Among them, for the functional expression in the exterior material 10, condensed phosphoric acids such as trimeta phosphoric acid, tetrameta phosphoric acid, hexameta phosphoric acid, and ultrameta phosphoric acid, or their alkali metal salts and ammonium salts are preferred. Also, considering the drying film-forming property (drying ability, heat quantity) when forming the corrosion prevention treatment layer 14 made of rare earth element oxide by various coating methods using the sol of the rare earth element oxide, sodium salts are more preferred from the viewpoint of excellent dehydration condensability at low temperatures. As the phosphate, a water-soluble salt is preferred.

[0047] The mixing ratio of phosphoric acid (or its salt) with respect to the rare earth element oxide is preferably 1 to 100 parts by mass with respect to 100 parts by mass of the rare earth element oxide. If the above mixing ratio is 1 part by mass or more with respect to 100 parts by mass of the rare earth element oxide, the rare earth element oxide sol becomes more stable and the function of the exterior material 10 becomes better. The above mixing ratio is more preferably 5 parts by mass or more with respect to 100 parts by mass of the rare earth element oxide. Further, if the above mixing ratio is 100 parts by mass or less with respect to 100 parts by mass of the rare earth element oxide, the function of the rare earth element oxide sol is enhanced. The above mixing ratio is more preferably 50 parts by mass or less, and even more preferably 20 parts by mass or less, with respect to 100 parts by mass of the rare earth element oxide.

[0048] Since the corrosion prevention treatment layer 14 formed by the above rare earth element oxide sol is an aggregate of inorganic particles, there is a possibility that the cohesive force of the layer itself may decrease even after the drying and curing process. Therefore, in this case, the corrosion prevention treatment layer 14 is preferably complexed with the following anionic polymer or cationic polymer in order to supplement the cohesive force.

[0049] Examples of anionic polymers include polymers having carboxy groups, such as poly(meth)acrylic acid (or its salts), or copolymers mainly composed of poly(meth)acrylic acid copolymerized therewith. Examples of the copolymer components of this copolymer include alkyl (meth)acrylate monomers (the alkyl group includes methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, t-butyl group, 2-ethylhexyl group, cyclohexyl group, etc.); amide group-containing monomers such as (meth)acrylamide, N-alkyl (meth)acrylamide, N,N-dialkyl (meth)acrylamide (the alkyl group includes methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, t-butyl group, 2-ethylhexyl group, cyclohexyl group, etc.), N-alkoxy (meth)acrylamide, N,N-dialkoxy (meth)acrylamide (the alkoxy group includes methoxy group, ethoxy group, butoxy group, isobutoxy group, etc.), N-methylol (meth)acrylamide, N-phenyl (meth)acrylamide; hydroxyl group-containing monomers such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate; glycidyl group-containing monomers such as glycidyl (meth)acrylate, allyl glycidyl ether; silane-containing monomers such as (meth)acryloxypropyltrimethoxysilane, (meth)acryloxypropyltriethoxysilane; isocyanate group-containing monomers such as (meth)acryloxypropyl isocyanate, etc.

[0050] These anionic polymers play a role in improving the stability of the corrosion prevention treatment layer 14 (oxide layer) obtained using the rare earth element oxide sol. This is achieved by the effect of protecting the hard and brittle oxide layer with an acrylic resin component and the effect of capturing (cation catcher) ionic contaminants (especially sodium ions) derived from phosphates contained in the rare earth element oxide sol. That is, when the corrosion prevention treatment layer 14 obtained using the rare earth element oxide sol contains alkali metal ions such as sodium or alkaline earth metal ions, the corrosion prevention treatment layer 14 is likely to deteriorate starting from the location containing these ions. Therefore, by immobilizing sodium ions and the like contained in the rare earth element oxide sol with an anionic polymer, the resistance of the corrosion prevention treatment layer 14 is improved.

[0051] The corrosion prevention treatment layer 14 combining the anionic polymer and the rare earth element oxide sol has the same corrosion prevention performance as the corrosion prevention treatment layer 14 formed by subjecting an aluminum foil to a chromate treatment. The anionic polymer preferably has a structure in which a polyanionic polymer that is essentially water-soluble is crosslinked. Examples of the crosslinking agent used for forming this structure include compounds having an isocyanate group, a glycidyl group, a carboxy group, and an oxazoline group.

[0052] Examples of the compound having an isocyanate group include diisocyanates such as tolylene diisocyanate, xylylene diisocyanate or its hydrogenated product, hexamethylene diisocyanate, 4,4'-diphenylmethane diisocyanate or its hydrogenated product, and isophorone diisocyanate; or polyisocyanates such as adducts obtained by reacting these isocyanates with polyhydric alcohols such as trimethylolpropane, biuret bodies obtained by reacting with water, or isocyanurate bodies which are trimers; or blocked polyisocyanates obtained by blocking these polyisocyanates with alcohols, lactams, oximes, etc.

[0053] Examples of the compound having a glycidyl group include epoxy compounds obtained by reacting epichlorohydrin with glycols such as ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, 1,4-butanediol, 1,6-hexanediol, and neopentyl glycol; epoxy compounds obtained by reacting epichlorohydrin with polyhydric alcohols such as glycerin, polyglycerin, trimethylolpropane, pentaerythritol, and sorbitol; and epoxy compounds obtained by reacting epichlorohydrin with dicarboxylic acids such as phthalic acid, terephthalic acid, oxalic acid, and adipic acid.

[0054] Examples of the compound having a carboxy group include various aliphatic or aromatic dicarboxylic acids. Further, poly(meth)acrylic acid or an alkali (earth) metal salt of poly(meth)acrylic acid may be used.

[0055] Examples of the compound having an oxazoline group include those obtained by copolymerizing acrylic monomers such as (meth)acrylic acid, (meth)acrylic acid alkyl ester, and (meth)acrylic acid hydroxyalkyl when using a low molecular compound having two or more oxazoline units or a polymerizable monomer such as isopropenyl oxazoline.

[0056] Further, an anionic polymer and a silane coupling agent are reacted, and more specifically, the carboxy group of the anionic polymer and the functional group of the silane coupling agent are selectively reacted, and the crosslinking points may be siloxane bonds. In this case, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-chloropropylmethoxysilane, vinyltrichlorosilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β(aminoethyl)-γ-aminopropyltrimethoxysilane, γ-isocyanatopropyltriethoxysilane, etc. can be used. Among them, considering the reactivity with the anionic polymer or its copolymer in particular, epoxy silane, amino silane, and isocyanate silane are preferable.

[0057] The ratio of these crosslinking agents to the anionic polymer is preferably 1 to 50 parts by mass, more preferably 10 to 20 parts by mass, per 100 parts by mass of the anionic polymer. If the ratio of the crosslinking agent is 1 part by mass or more per 100 parts by mass of the anionic polymer, a crosslinked structure is likely to be sufficiently formed. If the ratio of the crosslinking agent is 50 parts by mass or less per 100 parts by mass of the anionic polymer, the pot life of the coating solution is improved.

[0058] The method for crosslinking the anionic polymer is not limited to the above crosslinking agent, and may also be a method of forming an ionic crosslink using a titanium or zirconium compound.

[0059] Examples of cationic polymers include polymers having amines, such as polyethyleneimine, an ionomeric complex composed of polyethyleneimine and a polymer having a carboxylic acid, a primary amine-grafted acrylic resin obtained by grafting a primary amine onto an acrylic main skeleton, polyallylamine or its derivatives, and cationic polymers such as aminophenol. Examples of polyallylamine include homopolymers or copolymers such as allylamine, allylamine amide sulfate, diallylamine, and dimethylallylamine. These amines may be free amines or stabilizers with acetic acid or hydrochloric acid. Further, maleic acid, sulfur dioxide, etc. may be used as copolymer components. Furthermore, a type imparted with thermocrosslinkability by partially methoxylating a primary amine can also be used, and aminophenol can also be used. In particular, allylamine or its derivatives are preferred.

[0060] The cationic polymer is preferably used in combination with a crosslinking agent having a functional group capable of reacting with amines / imines such as a carboxy group or a glycidyl group. As the crosslinking agent used in combination with the cationic polymer, a polymer having a carboxylic acid that forms an ionomeric complex with polyethyleneimine can also be used. Examples include polycarboxylic acids (salts) such as polyacrylic acid or its ionic salts, or copolymers obtained by introducing a comonomer thereto, and polysaccharides having a carboxy group such as carboxymethyl cellulose or its ionic salts.

[0061] The cationic polymer is a more preferable material in terms of improving adhesiveness. Also, since the cationic polymer is water-soluble like the above-mentioned anionic polymer, it is more preferable to form a crosslinked structure to impart water resistance. As the crosslinking agent for forming the crosslinked structure in the cationic polymer, the crosslinking agent described in the section on the anionic polymer can be used. When a rare earth element oxide sol is used as the corrosion prevention treatment layer 14, a cationic polymer may be used instead of using the above-mentioned anionic polymer as the protective layer.

[0062] The corrosion prevention treatment layer by chemical conversion treatment typified by chromate treatment forms an inclined structure with the aluminum foil. Therefore, the aluminum foil is treated with a chemical conversion treatment agent containing hydrofluoric acid, hydrochloric acid, nitric acid, sulfuric acid, or salts thereof, and then a chromium or non-chromium compound is allowed to act to form a chemical conversion treatment layer on the aluminum foil. However, since the above chemical conversion treatment uses an acid in the chemical conversion treatment agent, it is accompanied by deterioration of the working environment and corrosion of the coating device. On the other hand, unlike the chemical conversion treatment typified by chromate treatment, the coating type corrosion prevention treatment layer 14 described above does not need to form an inclined structure with the barrier layer 13 using the aluminum foil. Therefore, the properties of the coating agent are not restricted by acidity, alkalinity, neutrality, etc., and a good working environment can be realized. In addition, the coating type corrosion prevention treatment layer 14 is preferable also from the point that a chromate treatment using a chromium compound requires an alternative in terms of environmental hygiene.

[0063] From the above content, as examples of the combination of the coating type corrosion prevention treatments described above, (1) only rare earth element oxide sol, (2) only an anionic polymer, (3) only a cationic polymer, (4) rare earth element oxide sol + anionic polymer (laminated composite), (5) rare earth element oxide sol + cationic polymer (laminated composite), (6) (rare earth element oxide sol + anionic polymer: laminated composite) / cationic polymer (multilayered), (7) (rare earth element oxide sol + cationic polymer: laminated composite) / anionic polymer (multilayered), etc. can be mentioned. Among them, (1) and (4) to (7) are preferable, and (4) to (7) are particularly preferable. However, the present embodiment is not limited to the above combination. For example, as an example of the selection of the corrosion prevention treatment, since the cationic polymer is also a very preferable material in terms of good adhesion to the modified polyolefin resin mentioned in the description of the second adhesive layer or the sealant layer to be described later, when the second adhesive layer or the sealant layer is composed of a modified polyolefin resin, a design such as providing a cationic polymer on the surface in contact with the second adhesive layer or the sealant layer (for example, the configurations such as (5) and (6)) is possible.

[0064] Further, the corrosion prevention treatment layer 14 is not limited to the layers described above. For example, like the coating type chromate which is a known technique, it may be formed using a treatment agent in which phosphoric acid and a chromium compound are blended in a resin binder (such as aminophenol). By using this treatment agent, a layer having both a corrosion prevention function and adhesiveness can be obtained. Also, although it is necessary to consider the stability of the coating liquid, a coating agent in which a rare earth element oxide sol and a polycationic polymer or a polyanionic polymer are liquefied in advance can be used to form a layer having both a corrosion prevention function and adhesiveness.

[0065] The mass per unit area of the corrosion prevention treatment layer 14 is preferably 0.005 to 0.200 g / m 2 and more preferably 0.010 to 0.100 g / m 2 If the mass per unit area is 0.005 g / m 2 or more, it is easy to impart a corrosion prevention function to the barrier layer 13. Also, even if the mass per unit area exceeds 0.200 g / m 2 the corrosion prevention function does not change much. On the other hand, when using a rare earth element oxide sol, if the coating film is thick, curing by heat during drying may be insufficient, and there is a risk of a decrease in cohesive force. Note that the thickness of the corrosion prevention treatment layer 14 can be converted from its specific gravity.

[0066] From the viewpoint of easily maintaining the adhesiveness between the sealant layer 16 and the barrier layer 13, the corrosion prevention treatment layer 14 may be, for example, a mode including cerium oxide, 1 to 100 parts by mass of phosphoric acid or phosphate with respect to 100 parts by mass of the cerium oxide, and a cationic polymer, or may be a mode formed by subjecting the barrier layer 13 to a chemical conversion treatment, or may be a mode formed by subjecting the barrier layer 13 to a chemical conversion treatment and including a cationic polymer.

[0067] <The second adhesive layer 17> The second adhesive layer 17 is a layer that adheres the barrier layer 13 on which the corrosion prevention treatment layer 14 is formed and the sealant layer 16. As the second adhesive layer 17, a general adhesive for adhering the barrier layer and the sealant layer can be used.

[0068] When the corrosion prevention treatment layer 14 has a layer containing at least one polymer selected from the group consisting of the cationic polymer and the anionic polymer described above, the second adhesive layer 17 is preferably a layer containing a compound (hereinafter also referred to as a "reactive compound") that is reactive with the polymer contained in the corrosion prevention treatment layer 14.

[0069] For example, when the corrosion prevention treatment layer 14 contains a cationic polymer, the second adhesive layer 17 contains a compound that is reactive with the cationic polymer. When the corrosion prevention treatment layer 14 contains an anionic polymer, the second adhesive layer 17 contains a compound that is reactive with the anionic polymer. When the corrosion prevention treatment layer 14 contains a cationic polymer and an anionic polymer, the second adhesive layer 17 contains a compound that is reactive with the cationic polymer and a compound that is reactive with the anionic polymer. However, the second adhesive layer 17 does not necessarily have to contain the above two types of compounds, and may contain a compound that is reactive with both the cationic polymer and the anionic polymer. Here, "being reactive" means forming a covalent bond with the cationic polymer or the anionic polymer. Further, the second adhesive layer 17 may further contain an acid-modified polyolefin resin.

[0070] Examples of the compound that is reactive with the cationic polymer include at least one compound selected from the group consisting of polyfunctional isocyanate compounds, glycidyl compounds, compounds having a carboxy group, and compounds having an oxazoline group.

[0071] Examples of these polyfunctional isocyanate compounds, glycidyl compounds, compounds having a carboxy group, and compounds having an oxazoline group include the polyfunctional isocyanate compounds, glycidyl compounds, compounds having a carboxy group, and compounds having an oxazoline group exemplified above as crosslinking agents for forming a crosslinked structure of the cationic polymer. Among these, polyfunctional isocyanate compounds are preferred in terms of high reactivity with the cationic polymer and ease of forming a crosslinked structure.

[0072] Examples of the compound having reactivity with the anionic polymer include at least one compound selected from the group consisting of glycidyl compounds and compounds having an oxazoline group. Examples of these glycidyl compounds and compounds having an oxazoline group include the glycidyl compounds and compounds having an oxazoline group exemplified above as crosslinking agents for forming a crosslinked structure of the cationic polymer. Among these, glycidyl compounds are preferred in terms of high reactivity with the anionic polymer.

[0073] When the second adhesive layer 17 contains an acid-modified polyolefin resin, the reactive compound preferably also has reactivity with the acidic groups in the acid-modified polyolefin resin (that is, forms a covalent bond with the acidic groups). Thereby, the adhesiveness with the corrosion prevention treatment layer 14 is further enhanced. In addition, the acid-modified polyolefin resin forms a crosslinked structure, and the solvent resistance of the exterior material 10 is further improved.

[0074] The content of the reactive compound is preferably from an equivalent amount to 10 times the equivalent amount with respect to the acidic groups in the acid-modified polyolefin resin. If it is an equivalent amount or more, the reactive compound sufficiently reacts with the acidic groups in the acid-modified polyolefin resin. On the other hand, if it exceeds 10 times the equivalent amount, since the crosslinking reaction with the acid-modified polyolefin resin has reached sufficient saturation, unreacted substances are present, and a decrease in various performances is a concern. Therefore, for example, the content of the reactive compound is preferably 5 to 20 parts by mass (solid content ratio) with respect to 100 parts by mass of the acid-modified polyolefin resin.

[0075] The acid-modified polyolefin resin is obtained by introducing an acidic group into the polyolefin resin. Examples of the acidic group include a carboxy group, a sulfonic acid group, an acid anhydride group, etc., and a maleic anhydride group, a (meth)acrylic acid group, etc. are particularly preferable. As the acid-modified polyolefin resin, for example, the same resin as the modified polyolefin resin (a) used for the first sealant layer 16a described later can be used.

[0076] Various additives such as a flame retardant, a slip agent, an antiblocking agent, an antioxidant, a light stabilizer, and a tackifier may be blended in the second adhesive layer 17.

[0077] From the viewpoints of suppressing a decrease in laminate strength and further suppressing a decrease in insulation properties, the second adhesive layer 17 may contain, for example, an acid-modified polyolefin and at least one curing agent selected from the group consisting of a polyfunctional isocyanate compound, a glycidyl compound, a compound having a carboxy group, a compound having an oxazoline group, and a carbodiimide compound. Examples of the carbodiimide compound include N,N'-di-o-tolylcarbodiimide, N,N'-diphenylcarbodiimide, N,N'-di-2,6-dimethylphenylcarbodiimide, N,N'-bis(2,6-diisopropylphenyl)carbodiimide, N,N'-dioctyldecylcarbodiimide, N-triyl-N'-cyclohexylcarbodiimide, N,N'-di-2,2-di-t-butylphenylcarbodiimide, N-triyl-N'-phenylcarbodiimide, N,N'-di-p-nitrophenylcarbodiimide, N,N'-di-p-aminophenylcarbodiimide, N,N'-di-p-hydroxyphenylcarbodiimide, N,N'-dicyclohexylcarbodiimide, N,N'-di-p-tolylcarbodiimide, etc.

[0078] In addition, as the adhesive for forming the second adhesive layer 17, for example, a polyurethane-based adhesive obtained by blending a polyester polyol composed of a hydrogenated dimer fatty acid and a diol and a polyisocyanate can also be used.

[0079] The thickness of the second adhesive layer 17 is not particularly limited, but from the viewpoint of obtaining a desired adhesive strength, workability, etc., it is preferably 1 to 10 μm, more preferably 3 to 7 μm.

[0080] <Sealant layer 16> The sealant layer 16 is a layer that imparts heat-sealing properties to the exterior material 10. The sealant layer 16 is composed of at least an ionomer.

[0081] When the sealant layer is a single layer as shown in FIG. 1, the sealant layer is an ionomer-containing layer containing an ionomer.

[0082] An ionomer is an ionic polymer material having an ion cross-linkage. For example, it has a structure in which the intermolecular spaces of a base copolymer such as an ethylene-methacrylic acid copolymer or an ethylene-acrylic acid copolymer are cross-linked with metal ions. As the ionomer, known ones can be used without particular limitation.

[0083] The metal ions constituting the ionomer are not particularly limited, and examples include zinc ions and sodium ions. From the viewpoint of more quickly and efficiently detoxifying hydrogen sulfide, zinc ions are preferred. The metal ions can be used alone or in combination of two or more.

[0084] Examples of the base copolymer constituting the ionomer include copolymers composed of α-olefins such as ethylene and propylene and α,β-unsaturated carboxylic acids such as acrylic acid, methacrylic acid, and maleic acid. From the viewpoint of heat-sealability, copolymers composed of ethylene or propylene and acrylic acid or methacrylic acid are preferred. The base copolymer can be used alone or in combination of two or more. In the present specification, an ionomer using ethylene as a constituent component of the base copolymer is also referred to as an "ethylene-based ionomer resin".

[0085] The ionomer-containing layer as the sealant layer 16 may be a layer composed only of an ionomer (an ionomer single layer having an ionomer content of 100% by mass), but may also contain components other than the above ionomer. The ionomer-containing layer as the sealant layer 16 may be composed of, for example, a base resin composition (hereinafter also referred to as "base resin composition") and an ionomer. In this specification, a sealant layer containing an ionomer and a resin other than the ionomer (base resin composition) is also referred to as a "mixed resin layer". Further, the mixed resin layer may further contain a compatibilizer having a site compatible with the resin contained in the base resin composition and a site compatible with the ionomer. Here, the base resin composition refers to the components excluding the ionomer and the compatibilizer from all the components constituting the sealant layer 16.

[0086] When the sealant layer 16 is a mixed resin layer containing an ionomer and a base resin composition, the content of the ionomer in the mixed resin layer may be 1% by mass or more and less than 100% by mass, 1 to 70% by mass, 1 to 40% by mass, or 5 to 20% by mass based on the total solid content of the mixed resin layer. By setting the content of the ionomer within the above range, it is easier to achieve both high heat sealability and the function of detoxifying hydrogen sulfide at a higher level.

[0087] The base resin composition is not particularly limited, and examples thereof include polyolefins such as polyethylene and polypropylene. As the base resin composition, for example, a resin composition (hereinafter sometimes referred to as "resin composition α") containing (A) 60 to 95% by mass of a propylene-ethylene random copolymer and (B) 5 to 40% by mass of a polyolefin-based elastomer having a melting point of 150°C or lower with butene-1 as a comonomer can be mentioned.

[0088] [Resin composition α] As described above, the resin composition α contains (A) 60 to 95% by mass of a propylene-ethylene random copolymer and (B) 5 to 40% by mass of a polyolefin-based elastomer having a melting point of 150°C or lower with butene-1 as a comonomer.

[0089] ((A) Propylene-ethylene random copolymer) (A) The propylene-ethylene random copolymer is excellent in heat sealability at low temperatures as compared with propylene-ethylene block copolymers and propylene homopolymers, and can improve the seal characteristics.

[0090] (A) In the propylene-ethylene random copolymer, the ethylene content is preferably 0.1 to 10% by mass, more preferably 1 to 7% by mass, and still more preferably 2 to 5% by mass. When the ethylene content is 0.1% by mass or more, the melting point lowering effect by copolymerizing ethylene can be sufficiently obtained, the seal characteristics can be further improved, impact resistance can be obtained, and the seal strength and resistance to molding whitening tend to be improved. When the ethylene content is 10% by mass or less, it is possible to suppress excessive lowering of the melting point and more sufficiently suppress the generation of an excessive seal portion. The ethylene content can be calculated from the mixing ratio of the monomers during polymerization.

[0091] (A) The melting point of the propylene-ethylene random copolymer is preferably 120 to 145°C, more preferably 125 to 140°C. When the melting point is 120°C or more, it is possible to more sufficiently suppress the generation of an excessive seal portion. When the melting point is 145°C or less, the seal characteristics tend to be further improved.

[0092] (A) The propylene-ethylene random copolymer may be acid-modified, for example, an acid-modified propylene-ethylene random copolymer obtained by graft-modifying maleic anhydride. By using the acid-modified propylene-ethylene random copolymer, the adhesion to the tab lead can be maintained without a tab sealant.

[0093] (A) The propylene-ethylene random copolymer can be used alone or in combination of two or more.

[0094] In the resin composition α, the content of the component (A) is 60 to 95% by mass, preferably 60 to 90% by mass, and more preferably 60 to 85% by mass based on the total solid content of the resin composition α. When the content of the component (A) is 60% by mass or more, the sealing properties can be improved due to the effect of using the component (A) itself. Further, by setting the content of the component (A) to 60% by mass or more, the excessive presence of the component (B) can be prevented, so that the decrease in the heat resistance of the sealant layer 16 can be suppressed, and the generation of an excessive seal portion can be suppressed. On the other hand, by setting the content of the component (A) to 95% by mass or less, the component (B) can be contained in an amount of 5% by mass or more, so that the effect of improving the heat seal strength by the component (B) can be sufficiently obtained.

[0095] ((B) A polyolefin elastomer having a melting point of 150 ° C or lower with butene-1 as a comonomer) The polyolefin elastomer (B) having a melting point of 150 ° C or lower with butene-1 as a comonomer contributes to the improvement of the sealing properties and also contributes to the suppression of the occurrence of molding whitening.

[0096] The (B) polyolefin elastomer may or may not be compatible with the (A) component, but it preferably includes both a (B-1) compatible polyolefin elastomer having compatibility and a (B-2) incompatible polyolefin elastomer having no compatibility. Here, when the resin constituting the component (A) is a propylene-ethylene random copolymer, being compatible with the component (A) (compatible system) means being dispersed in the propylene-ethylene random copolymer resin constituting the component (A) with a dispersed phase size of 1 nm or more and less than 500 nm. Having no compatibility (incompatible system) means being dispersed in the propylene-ethylene random copolymer resin constituting the component (A) with a dispersed phase size of 500 nm or more and less than 20 μm.

[0097] (B-1) Examples of the compatible polyolefin-based elastomer include a propylene-butene-1 random copolymer.

[0098] (B-2) Examples of the incompatible polyolefin-based elastomer include an ethylene-butene-1 random copolymer.

[0099] (B) The melting point of the polyolefin-based elastomer needs to be 150°C or lower. From the viewpoints of suppressing the excessive seal portion, suppressing molding whitening, and improving the seal characteristics, it is preferably 60 to 120°C, and more preferably 65 to 90°C. By having a melting point of 150°C or lower, the seal characteristics can be improved. Also, when the melting point is 60°C or higher, it is advantageous from the viewpoint of suppressing the generation of the excessive seal portion.

[0100] (B) The polyolefin-based elastomer can be used alone or in combination of two or more.

[0101] In the resin composition α, the content of the component (B) is 5 to 40% by mass based on the total solid content of the resin composition α, preferably 10 to 40% by mass, and more preferably 15 to 40% by mass. By having a content of the component (B) of 5% by mass or more, the effect of improving the seal characteristics can be sufficiently obtained. On the other hand, by setting the content of the component (B) to 40% by mass or less, a decrease in the heat resistance of the sealant layer 16 can be suppressed, and the generation of the excessive seal portion can be suppressed.

[0102] When the component (B) contains a (B-1) compatible polyolefin-based elastomer and a (B-2) incompatible polyolefin-based elastomer, the content ratio thereof ((B-1) compatible polyolefin-based elastomer / (B-2) incompatible polyolefin-based elastomer) is preferably 0.5 to 3 in terms of mass ratio, and more preferably 1 to 2. By setting the content ratio within the above range, the anti-molding whitening property and the seal characteristics can be improved in a well-balanced manner.

[0103] (Additive components) The resin composition α may further contain other components other than the above-mentioned components (A) and (B). As other components other than the components (A) and (B), for example, other resins such as LDPE (low-density polyethylene) may be added to improve pick-up properties and processability. When the total mass of the sealant layer 16 is 100 parts by mass, the content of the other resin component to be added is preferably 10 parts by mass or less. Further, examples of components other than resins include slip agents, antiblocking agents, antioxidants, light stabilizers, flame retardants, and the like. When the total mass of the sealant layer 16 is 100 parts by mass, the content of these other components other than resins is preferably 5 parts by mass or less.

[0104] In the sealant layer 16, the presence of butene-1 can be confirmed by attribution using FT-IR (Fourier transform infrared spectrophotometer). Further, the content of butene-1 can be confirmed by preparing a calibration curve with the transmittance or absorbance of the characteristic absorption bands of the components (A) and (B) using a resin composition α containing a known amount of an elastomer containing a known amount of butene-1. Furthermore, regarding the butene-1 content of each of the (B-1) compatible polyolefin-based elastomer and the (B-2) incompatible polyolefin-based elastomer, imaging can also be performed at the characteristic absorption band of FT-IR in the same manner, and mapping can be performed at the absorption band attributed to butene-1 by microscopic FT-IR (transmission method) for confirmation. In addition to FT-IR, it is also possible to confirm the presence and content of butene-1 by measuring the sealant layer 16 by NMR.

[0105] [Compatibilizer] The sealant layer 16 is a mixed resin layer containing an ionomer and a base resin composition. When the ionomer is incompatible with the resin contained in the base resin composition, it is preferable that the mixed resin layer further contains a compatibilizer having a site compatible with the resin contained in the base resin composition and a site compatible with the ionomer. For example, when the resin contained in the base resin composition is a polypropylene-based resin such as (A) a propylene-ethylene random copolymer and the ionomer is an ethylene-based ionomer resin incompatible with the polypropylene-based resin, it is preferable that the mixed resin layer contains a compatibilizer having a site compatible with the above polypropylene-based resin and a site compatible with the above ethylene-based ionomer resin. When the ionomer is incompatible with the resin contained in the base resin composition, the mixed resin layer will have a sea-island structure in which the ionomer is dispersed in the resin contained in the base resin composition. By adding the above compatibilizer thereto, the adhesion strength at the interface of the sea-island structure can be improved, thereby further improving the seal strength after heat sealing. Incidentally, the above compatibilizer may also improve the adhesion strength at the interface of the sea-island structure formed by the (A) component and the (B) component in the resin composition α described above.

[0106] Examples of the compatibilizer include graft copolymers and block copolymers. Examples of suitable graft copolymers as the compatibilizer include graft copolymers composed of a polyolefin main chain and a polystyrene side chain, graft copolymers composed of a polyolefin main chain and a styrene-acrylonitrile copolymer side chain, and the like. As the above graft copolymer, for example, "Modiper" manufactured by NOF Corporation is suitable.

[0107] Examples of block copolymers suitable as compatibilizers include block copolymers having a block composed of styrene units and a block composed of ethylene-butylene units, block copolymers having a block composed of styrene units, a block composed of ethylene-butylene units, and a block composed of crystalline olefin units, block copolymers having a block composed of crystalline ethylene units and a block composed of ethylene-butylene units, block copolymers having a block composed of ethylene and a block composed of ethylene-octene 1, and block copolymers having a block composed of propylene units and a block composed of ethylene units. For example, the block composed of propylene units is a site compatible with polypropylene-based resins such as the above (A) propylene-ethylene random copolymer, and the block composed of ethylene units is a site compatible with ionomers such as ethylene-based ionomer resins. Examples of the above block copolymers include "DYNARON" manufactured by JSR Corporation, "INTUNE" and "INFUSE" manufactured by DOW Chemical Company, etc.

[0108] When the mixed resin layer contains a compatibilizer, the content of the compatibilizer in the mixed resin layer is preferably 1 to 40% by mass, more preferably 2 to 25% by mass, still more preferably 2 to 20% by mass, and particularly preferably 7 to 15% by mass, based on the total solid content of the mixed resin layer. When the content of the compatibilizer is 1% by mass or more, it becomes easier to improve the adhesion strength at the sea-island interface, and the effect of improving the seal strength is easily obtained. On the other hand, when the content of the compatibilizer is 40% by mass or less, it becomes easier to suppress the decrease in the cohesive force of the entire sealant layer 16 and the seal strength.

[0109] The thickness of the sealing layer 16 is not particularly limited, but for example, it is preferably in the range of 5 to 100 μm, more preferably in the range of 20 to 80 μm. Further, from the viewpoint of thinning the film, the thickness of the sealing layer 16 may be 30 μm or less. Even with such a thin film configuration, the exterior material for all-solid-state batteries of the present embodiment can suppress a decrease in crack resistance after heat sealing and molding, detoxify hydrogen sulfide, and suppress corrosion of the current collector.

[0110] As described above, the preferred embodiments of the exterior material for all-solid-state batteries of the present embodiment have been described in detail. However, the present disclosure is not limited to such specific embodiments, and various modifications and changes are possible within the scope of the gist of the present disclosure described in the claims.

[0111] For example, in FIG. 1, the case where the corrosion prevention treatment layer 14 is formed on the surface of the barrier layer 13 on the side of the second adhesive layer 17 is shown. However, the corrosion prevention treatment layer 14 may be formed on the surface of the barrier layer 13 on the side of the first adhesive layer 12, or may be formed on both surfaces of the barrier layer 13. When the corrosion prevention treatment layers 14 are formed on both surfaces of the barrier layer 13, the configuration of the corrosion prevention treatment layer 14 formed on the side of the first adhesive layer 12 of the barrier layer 13 and the configuration of the corrosion prevention treatment layer 14 formed on the side of the second adhesive layer 17 of the barrier layer 13 may be the same or different. Further, the corrosion prevention treatment layer 14 may not be provided on either surface of the barrier layer 13.

[0112] In FIG. 1, the case where the barrier layer 13 and the sealing layer 16 are laminated using the second adhesive layer 17 is shown. However, the sealing layer 16 may be directly formed on the barrier layer 13 without using the second adhesive layer 17 as in the exterior material 20 for all-solid-state batteries shown in FIG. 2 and the exterior material 30 for all-solid-state batteries shown in FIG. 3. On the other hand, the exterior material 20 for all-solid-state batteries shown in FIG. 2 and the exterior material 30 for all-solid-state batteries shown in FIG. 3 may also include a second adhesive layer 17 between the barrier layer 13 and the sealing layer 16.

[0113] In FIG. 1, the case where the sealant layer 16 is formed of a single layer is shown. However, the sealant layer 16 may be formed of two or more layers like the outer packaging material 20 for all-solid-state battery shown in FIG. 2 and the outer packaging material 30 for all-solid-state battery shown in FIG. 3. The configuration of each layer of the multilayer forming the sealant layer 16 may be the same or different. When the sealant layer 16 is multilayer, at least one of the layers is an ionomer-containing layer containing an ionomer.

[0114] In the outer packaging material 20 for all-solid-state battery shown in FIG. 2, the sealant layer 16 is composed of a first sealant layer 16a and a second sealant layer 16b. Here, the first sealant layer 16a is the outermost layer of the sealant layer, and the second sealant layer 16b is the innermost layer of the sealant layer. At least one layer selected from the group consisting of the first sealant layer 16a and the second sealant layer 16b is an ionomer-containing layer containing the above ionomer. The ionomer-containing layer may be an ionomer single layer composed only of an ionomer as described above, or a mixed resin layer containing an ionomer, a base resin composition, and a compatibilizer as necessary.

[0115] The second sealant layer 16b (innermost layer) can be formed, for example, using the same components as the sealant layer 16 in the outer packaging material 10 described above. When the second sealant layer 16b is an ionomer-containing layer, the detoxification of hydrogen sulfide can be carried out more quickly and efficiently.

[0116] Also, the second sealant layer 16b may be formed using a material obtained by removing an ionomer and a compatibilizer from the material forming the sealant layer 16 in the outer packaging material 10 described above.

[0117] The thickness of the second sealant layer 16b is not particularly limited, but specifically, for example, it is preferably in the range of 5 to 100 μm, and may be in the range of 10 to 30 μm from the viewpoint of thinning.

[0118] The first sealant layer 16a (the outermost layer, the metal foil side layer) may be formed using, for example, the same components as those of the second sealant layer 16b. However, in the first sealant layer 16a, for example, instead of the resin composition α as the base resin composition, a resin composition (hereinafter, sometimes referred to as "resin composition β") containing an adhesive resin composition as the main component in consideration of aluminum treatment and adhesiveness and an additive component as necessary is preferably used. That is, the first sealant layer 16a may be formed, for example, from an ionomer, the resin composition β, and a compatibilizer as necessary, or may be formed only from the resin composition β. When the first sealant layer 16a contains an adhesive resin composition, it is easy to form a sealant layer on the barrier layer without using an adhesive layer. When the first sealant layer 16a is formed from an ionomer, the resin composition β, and a compatibilizer as necessary, there is a tendency to easily maintain the adhesion between the sealant layer and the barrier layer.

[0119] [Resin composition β (excluding the above ionomer)] The adhesive resin composition in the resin composition β is not particularly limited, but preferably contains a modified polyolefin resin (a) component and a macro phase-separated thermoplastic elastomer (b) component. The additive component preferably includes an atactic polypropylene or an atactic propylene-α olefin copolymer (c). Hereinafter, each component will be described.

[0120] (Modified polyolefin resin (a)) The modified polyolefin resin (a) is preferably a resin in which an unsaturated carboxylic acid derivative component derived from any one of an unsaturated carboxylic acid, an acid anhydride of an unsaturated carboxylic acid, and an ester of an unsaturated carboxylic acid is graft-modified to a polyolefin resin.

[0121] Examples of the polyolefin resin include polyolefin resins such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, ethylene-α olefin copolymer, homopolypropylene, block polypropylene, or random polypropylene, and propylene-α olefin copolymer.

[0122] Examples of the compound used for graft-modifying these polyolefin resins include unsaturated carboxylic acid derivative components derived from any of unsaturated carboxylic acids, acid anhydrides of unsaturated carboxylic acids, and esters of unsaturated carboxylic acids.

[0123] Specific examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, tetrahydrophthalic acid, bicyclo[2,2,1]hept-2-ene-5,6-dicarboxylic acid, and the like.

[0124] Examples of the acid anhydride of the unsaturated carboxylic acid include acid anhydrides of unsaturated carboxylic acids such as maleic anhydride, itaconic anhydride, citraconic anhydride, tetrahydrophthalic anhydride, bicyclo[2,2,1]hept-2-ene-5,6-dicarboxylic anhydride, and the like.

[0125] Examples of the ester of the unsaturated carboxylic acid include esters of unsaturated carboxylic acids such as methyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dimethyl maleate, monomethyl maleate, diethyl fumarate, dimethyl itaconate, diethyl citraconate, dimethyl tetrahydrophthalate, dimethyl bicyclo[2,2,1]hept-2-ene-5,6-dicarboxylate, and the like.

[0126] The modified polyolefin resin (a) can be produced by subjecting 0.2 to 100 parts by mass of the above-described unsaturated carboxylic acid derivative component to graft polymerization (graft modification) in the presence of a radical initiator with respect to 100 parts by mass of the base polyolefin resin. The reaction temperature for graft modification is preferably 50 to 250°C, more preferably 60 to 200°C. The reaction time is appropriately set according to the production method. For example, in the case of melt graft polymerization using a twin-screw extruder, within the residence time of the extruder, specifically 2 to 30 minutes is preferable, and 5 to 10 minutes is more preferable. Note that the graft modification can be carried out under any conditions of normal pressure or pressure.

[0127] Examples of radical initiators used for graft modification include organic peroxides such as alkyl peroxide, aryl peroxide, acyl peroxide, ketone peroxide, peroxyketal, peroxicarbonate, peroxyester, and hydroperoxide.

[0128] These organic peroxides can be appropriately selected and used according to the above-described reaction temperature and reaction time conditions. For example, in the case of melt graft polymerization using a twin-screw extruder, alkyl peroxide, peroxyketal, and peroxyester are preferred. Specifically, di-t-butyl peroxide, 2,5-dimethyl-2,5-di-t-butylperoxy-hexyne-3, dicumyl peroxide, etc. are preferred.

[0129] As the modified polyolefin resin (a), a polyolefin resin modified with maleic anhydride is preferred. For example, "Admer" manufactured by Mitsui Chemicals, "Modic" manufactured by Mitsubishi Chemical Corporation, etc. are suitable. Since such a modified polyolefin resin (a) component has excellent reactivity with polymers having various metals and various functional groups, the reactivity can be utilized to impart adhesion to the first sealant layer 16a.

[0130] (Macro phase-separated thermoplastic elastomer (b)) The macro phase-separated thermoplastic elastomer (b) forms a macro phase-separated structure in a range where the dispersed phase size exceeds 200 nm and is 50 μm or less with respect to the modified polyolefin resin (a).

[0131] When the adhesive resin composition contains the macro phase-separated thermoplastic elastomer (b) component, the residual stress generated when laminating the modified polyolefin resin (a) component, etc., which can be the main component constituting the first sealant layer 16a, can be released, and viscoelastic adhesiveness can be imparted to the first sealant layer 16a. Therefore, an exterior material 20 with improved adhesion of the first sealant layer 16a can be obtained.

[0132] The macro phase-separated thermoplastic elastomer (b) exists in a sea-island structure on the modified polyolefin resin (a). However, when the dispersed phase size is 200 nm or less, it becomes difficult to impart an improvement in viscoelastic adhesion. On the other hand, when the dispersed phase size exceeds 50 μm, since the modified polyolefin resin (a) and the macro phase-separated thermoplastic elastomer (b) are essentially incompatible, the laminate suitability (processability) is significantly reduced, and the physical strength of the first sealant layer 16a is likely to decrease. From the above, the dispersed phase size is preferably 500 nm to 10 μm.

[0133] Examples of such macro phase-separated thermoplastic elastomers (b) include polyolefin-based thermoplastic elastomers obtained by copolymerizing ethylene and / or propylene with an α-olefin selected from 1-butene, 1-pentene, 1-hexene, 1-octene, and 4-methyl-1-pentene.

[0134] In addition, as the macro phase-separated thermoplastic elastomer (b) component, commercially available products can be used. For example, "Tafmer" manufactured by Mitsui Chemicals, "Zelas" manufactured by Mitsubishi Chemical, "Catalloy" manufactured by Montell, etc. are suitable.

[0135] In the above resin composition β, the content of the macro phase-separated thermoplastic elastomer (b) component with respect to the modified polyolefin resin (a) component is preferably 1 to 40 parts by mass, and more preferably 5 to 30 parts by mass, per 100 parts by mass of the modified polyolefin resin (a) component. Here, when the content of the macro phase-separated thermoplastic elastomer (b) component is less than 1 part by mass, improvement in the adhesion of the first sealant layer cannot be expected. On the other hand, when the content of the macro phase-separated thermoplastic elastomer (b) component exceeds 40 parts by mass, since the modified polyolefin resin (a) component and the macro phase-separated thermoplastic elastomer (b) component are inherently low in compatibility, the processability is likely to be significantly reduced. Further, since the macro phase-separated thermoplastic elastomer (b) component is not a resin exhibiting adhesiveness, the adhesion of the first sealant layer 16a to other layers such as the second sealant layer 16b and the corrosion prevention treatment layer 14 is likely to decrease.

[0136] (Atactic polypropylene or propylene-α-olefin copolymer with atactic structure (c)) It is preferable that the resin composition β contains, as an additive component, atactic polypropylene or a propylene-α-olefin copolymer with an atactic structure (hereinafter simply referred to as "component (c)"). Here, component (c) is a completely amorphous resin component.

[0137] Hereinafter, in the resin composition β, the effect of adding the additive component (c) to the adhesive resin composition as the main component will be described.

[0138] Component (c) is compatible with the modified polyolefin resin (a) component in the adhesive resin composition in the molten state, but is discharged outside the crystal during crystallization accompanying cooling and is uniformly dispersed around the spherulites. As a result, component (c) does not inhibit the crystallinity of the modified polyolefin resin (a) component in the adhesive resin composition as the main component. Further, by adding component (c) to the resin composition β, the concentration of the modified polyolefin resin (a) component is diluted by component (c) and crystal growth is suppressed, so that the crystal size (spherulite size) of the adhesive component of the base resin (that is, the modified polyolefin resin (a) component) can be reduced. In addition, component (c) discharged outside the crystal is uniformly dispersed around the fine spherulites of the modified polyolefin resin (a) component.

[0139] By the way, it has been conventionally known that a "whitening phenomenon" occurs when cold-molding an exterior material. Here, the mechanism of the whitening phenomenon will be described. (1) By the heat treatment during heat lamination, the modified polyolefin resin (a) in the resin composition β crystallizes. (2) Since the modified polyolefin resin (a) and the macro-phase-separated thermoplastic elastomer (b) are incompatible, strain occurs at the interface between the two due to the crystallization behavior in (1). (3) When stress is applied during molding, cracks occur at the interface between the two, forming void-crazes. (4) Light is scattered by void-crazes, causing a whitening phenomenon due to optical irregular reflection of light.

[0140] That is, in order to suppress the whitening phenomenon, "the crystallization of the modified polyolefin resin (a) does not progress (i.e., it is made difficult to crystallize) with the amount of heat during thermal lamination" and "the adhesion between the modified polyolefin resin (a) and the macro-phase-separating thermoplastic elastomer (b) is improved" are known to be important.

[0141] On the other hand, by adding the component (c) as an additive component to the adhesive resin composition that can be the main component of the first sealant layer 16a, the crystal size (spherulite size) of the modified polyolefin resin (a) component can be reduced, so that flexible and sticky film properties can be obtained. In addition, since the component (c) is uniformly dispersed around the modified polyolefin resin (a), stress relaxation can be achieved uniformly, and the generation of void crazes can be suppressed. Therefore, it is considered possible to alleviate the "whitening phenomenon" of the exterior material 20 accompanying the stress during molding.

[0142] As described above, by adding the component (c) as an additive component to the adhesive resin composition that can be the main component of the first sealant layer 16a, the transparency of the first sealant layer 16a can be increased, and the whitening phenomenon accompanying the stress during molding can be alleviated. As a result, molding whitening is also improved, and it becomes possible to improve the crack resistance of the exterior material 20 accompanying the bending stress. In addition, since the crystallinity of the modified polyolefin resin component (a) in the first sealant layer 16a is maintained while flexibility can be imparted, it is possible to suppress a decrease in the bending resistance (crack resistance) of the exterior material 20.

[0143] (Isotactic propylene-α-olefin copolymer (d)) The resin composition β may further contain, as an additive component, an isotactic propylene-α-olefin copolymer (hereinafter simply referred to as "component (d)") in addition to the above-described component (c).

[0144] By adding component (d) as an additive component to the adhesive resin component, which is the main component of resin composition β, flexibility for stress relaxation can be imparted, thus enabling improvement of the heat seal strength. Further, by combining component (c) and component (d) as the additive components, the whitening phenomenon and the flex resistance can be further improved.

[0145] In resin composition β, the total mass of component (a) and component (b) may be, for example, 60% by mass or more and 95% by mass or less, or 80% by mass or more and 90% by mass or less, based on the total mass of the first sealant layer 16a.

[0146] In resin composition β, the total mass of component (c) and component (d) is preferably, for example, 5% by mass or more and 40% by mass or less, based on the total mass of component (a), component (b), component (c) and component (d). When the total mass of component (c) and component (d) is less than 5% by mass based on the total mass of component (a), component (b), component (c) and component (d), the effects of adding the above-described additives tend not to be sufficiently obtained. On the other hand, when the total mass of component (c) and component (d) exceeds 40% by mass based on the total mass of component (a), component (b), component (c) and component (d), the adhesion of the first sealant layer 16a to other layers such as the second sealant layer 16b and the corrosion prevention treatment layer 14 tends to decrease. From these viewpoints, in resin composition β, the total mass of component (a) and component (b) is preferably, for example, 60 to 95% by mass, based on the total mass of component (a), component (b), component (c) and component (d).

[0147] Note that as a method for analyzing component (c), which is an additive component, in resin composition β, for example, it is possible to quantify by stereoregularity evaluation using nuclear magnetic resonance spectroscopy (NMR).

[0148] On the other hand, as for the analysis of component (d), a calibration curve is created using Fourier transform infrared spectroscopy (FT-IR) with the absorbers attributed to the branching of α-olefins and the absorbers attributed to the characteristic absorbers of the modified polyolefin resin (a), whereby the blending ratio can be confirmed.

[0149] In addition to the adhesive resin composition (i.e., the modified polyolefin resin (a) component and the macro-phase separation thermoplastic elastomer (b) component) and the additive components (i.e., component (c) and component (d)), the resin composition β may contain various additives as necessary, such as flame retardants, slip agents, anti-blocking agents, antioxidants, light stabilizers, tackifiers, and the like.

[0150] The thickness of the first sealant layer 16a is not particularly limited, but from the viewpoints of stress relaxation and water permeation, it is preferably the same as or less than that of the second sealant layer 16b.

[0151] Also, in the exterior material 20 for all-solid-state batteries, from the viewpoint of thinning, the thickness of the sealant layer 16 (the total thickness of the first sealant layer 16a and the second sealant layer 16b) may be 35 μm or less, or may be 30 μm or less. Even with such a thin film structure, the exterior material for all-solid-state batteries of this embodiment can suppress a decrease in crack resistance after heat sealing and molding, can detoxify hydrogen sulfide, and can suppress corrosion of the current collector.

[0152] In FIG. 2, the case where the sealant layer 16 is formed of two layers is shown, but the sealant layer 16 may be formed of three layers like the exterior material 30 for all-solid-state battery shown in FIG. 3. In the exterior material 30 for all-solid-state battery shown in FIG. 3, the sealant layer 16 is composed of a first sealant layer 16a, a second sealant layer 16b, and a third sealant layer 16c. Here, the first sealant layer 16a is the outermost layer of the sealant layer (the layer on the metal foil side), the third sealant layer 16c is the intermediate layer of the sealant layer, and the second sealant layer 16b is the innermost layer of the sealant layer. At least one layer selected from the group consisting of these three layers is an ionomer-containing layer containing the above ionomer.

[0153] Examples and preferred forms of the material constituting the first sealant layer 16a of the exterior material 30 for all-solid-state battery are the same as those of the first sealant layer 16a of the exterior material 20 for all-solid-state battery.

[0154] Examples and preferred forms of the material constituting the second sealant layer 16b and the third sealant layer 16c of the exterior material 30 for all-solid-state battery are the same as those of the second sealant layer 16b of the exterior material 20 for all-solid-state battery.

[0155] In the exterior material 30 for all-solid-state battery, the thickness of the first sealant layer 16a may be, for example, 2 to 30 μm, may be 5 to 20 μm, may be 8 to 10 μm, the thickness of the second sealant layer 16b may be, for example, 10 to 80 μm, may be 13 to 40 μm, may be 15 to 20 μm, and the thickness of the third sealant layer 16c may be, for example, 2 to 30 μm, may be 5 to 20 μm, may be 8 to 10 μm.

[0156] Even in the outer packaging material 30 for all-solid-state batteries, from the perspective of thinning, the thickness of the sealant layer 16 (the total thickness of the first sealant layer 16a, the second sealant layer 16b, and the third sealant layer 16c) may be 30 μm or less. Even with such a thin film structure, the outer packaging material for all-solid-state batteries of the present embodiment can suppress a decrease in crack resistance after heat sealing and molding, can detoxify hydrogen sulfide, and can suppress corrosion of the current collector.

[0157] When the sealant layer 16 is composed of a plurality of layers, such as the outer packaging materials 20 and 30 for all-solid-state batteries, the sealant layer 16 may include an ionomer single layer composed only of an ionomer and a base resin composition layer containing a base resin composition and not containing an ionomer. When the sealant layer has a two-layer structure as shown in FIG. 2, examples of the laminated structure of the first sealant layer 16a / the second sealant layer 16b include an ionomer single layer / base resin composition layer and a base resin composition layer / ionomer single layer laminated structures. Further, when the sealant layer has a three-layer structure as shown in FIG. 3, examples of the laminated structure of the first sealant layer 16a / the third sealant layer 16c / the second sealant layer 16b include an ionomer single layer / base resin composition layer / ionomer single layer and a base resin composition layer / ionomer single layer / base resin composition layer laminated structures. Among these, from the perspective of obtaining better heat sealability, a laminated structure in which the second sealant layer 16b, which is the innermost layer, is a base resin composition layer is preferable. Also, from the perspective of further improving heat sealability, the ionomer single layer in the above-described laminated structure may be changed to a mixed resin layer, and from the perspective of further promoting the detoxification of hydrogen sulfide, the base resin composition layer in the above-described laminated structure may be changed to a mixed resin layer.

[0158] Also, in the outer packaging materials 20 and 30 for all-solid-state batteries shown in FIGS. 2 and 3, a second adhesive layer 17 may be provided between the sealant layer 16 and the corrosion prevention treatment layer 14 from the perspective of improving the adhesion between the sealant layer 16 and the corrosion prevention treatment layer 14 as shown in FIG. 1.

[0159] [Method for manufacturing exterior material] Next, an example of the manufacturing method of the exterior material 10 shown in FIG. 1 will be described. Note that the manufacturing method of the exterior material 10 is not limited to the following method.

[0160] The manufacturing method of the exterior material 10 of the present embodiment generally includes a step of laminating a corrosion prevention treatment layer 14 on the barrier layer 13, a step of bonding the base material layer 11 and the barrier layer 13, a step of further laminating a sealant layer 16 through a second adhesive layer 17 to produce a laminate, and a step of aging the obtained laminate as needed.

[0161] (Step of laminating the corrosion prevention treatment layer 14 on the barrier layer 13) This step is a step of forming a corrosion prevention treatment layer 14 on the barrier layer 13. As the method, as described above, methods such as subjecting the barrier layer 13 to degreasing treatment, hot water conversion treatment, anodizing treatment, chemical conversion treatment, or applying a coating agent having corrosion prevention performance can be mentioned.

[0162] Also, when the corrosion prevention treatment layer 14 is multilayered, for example, a coating liquid (coating agent) constituting the corrosion prevention treatment layer on the lower layer side (barrier layer 13 side) is applied to the barrier layer 13 and baked to form the first layer, and then a coating liquid (coating agent) constituting the corrosion prevention treatment layer on the upper layer side is applied to the first layer and baked to form the second layer.

[0163] For the degreasing treatment, the spray method or the dipping method can be used. For the hot water conversion treatment and the anodizing treatment, the dipping method can be used. For the chemical conversion treatment, the dipping method, the spray method, the coating method, etc. can be appropriately selected according to the type of the chemical conversion treatment.

[0164] Regarding the coating method of the coating agent having corrosion prevention performance, various methods such as gravure coating, reverse coating, roll coating, and bar coating can be used.

[0165] As described above, various processes may be performed on either one or both sides of the metal foil. In the case of single-sided processing, it is preferable that the processed surface be the side on which the second adhesive layer 17 is laminated. Additionally, if required, the above-described processing may also be performed on the surface of the base material layer 11.

[0166] Also, the coating amount of the coating agent for forming the first layer and the second layer is preferably in the range of 0.005 to 0.200 g / m 2 and more preferably in the range of 0.010 to 0.100 g / m 2 .

[0167] Also, when drying and curing are required, depending on the drying conditions of the corrosion prevention treatment layer 14 used, it can be carried out in the range of 60 to 300 °C as the base material temperature.

[0168] (Lamination process of the base material layer 11 and the barrier layer 13) This process is a process of laminating the barrier layer 13 provided with the corrosion prevention treatment layer 14 and the base material layer 11 via the first adhesive layer 12. As the lamination method, methods such as dry lamination, non-solvent lamination, and wet lamination are used, and the two are laminated with the material constituting the above-described first adhesive layer 12. The first adhesive layer 12 is provided in the range of 1 to 10 g / m 2 as the dry coating amount, and more preferably in the range of 3 to 7 g / m 2 .

[0169] (Lamination process of the second adhesive layer 17 and the sealant layer 16) This process is a process of laminating the sealant layer 16 via the second adhesive layer 17 on the corrosion prevention treatment layer 14 side of the barrier layer 13. Examples of the lamination method include the wet process and dry lamination.

[0170] In the case of the wet process, a solution or dispersion of the adhesive constituting the second adhesive layer 17 is applied onto the corrosion prevention treatment layer 14, and the solvent is evaporated and dried to form a film at a predetermined temperature (when the adhesive contains an acid-modified polyolefin resin, a temperature equal to or higher than its melting point), or a baking treatment is performed as necessary after the drying and film formation. Then, the sealant layer 16 is laminated to manufacture the exterior material 10. Examples of the coating method include the various coating methods exemplified above.

[0171] (Aging treatment step) This step is a step of aging (curing) the laminate. By aging the laminate, the adhesion between the barrier layer 13 / corrosion prevention treatment layer 14 / second adhesive layer 17 / sealant layer 16 can be promoted. The aging treatment can be performed in the range of room temperature to 100 °C. The aging time is, for example, 1 to 10 days. Also, in order to bond the second adhesive layer 17 / sealant layer 16, it is possible to perform a heat treatment at a temperature equal to or higher than the melting point of the second adhesive layer 17. Examples of the heat treatment include, but are not limited to, oven heating, sandwiching with heated rolls (heat lamination), winding around a heated roll, etc.

[0172] In this way, the exterior material 10 of the present embodiment as shown in FIG. 1 can be manufactured.

[0173] Next, an example of a method for manufacturing the exterior material 20 shown in FIG. 2 will be described. Note that the manufacturing method of the exterior material 20 is not limited to the following method.

[0174] The manufacturing method of the exterior material 20 of the present embodiment generally includes a step of laminating the corrosion prevention treatment layer 14 on the barrier layer 13, a step of bonding the base material layer 11 and the barrier layer 13, a step of further laminating the first sealant layer 16a and the second sealant layer 16b to form a laminate, and a step of heat-treating the obtained laminate as necessary. Note that up to the step of bonding the base material layer 11 and the barrier layer 13, it can be performed in the same manner as the manufacturing method of the exterior material 10 described above.

[0175] (Lamination process of the first sealant layer 16a and the second sealant layer 16b) This process is a process of forming the first sealant layer 16a and the second sealant layer 16b on the corrosion prevention treatment layer 14 formed in the previous process. As a method thereof, a method of sand laminating the first sealant layer 16a together with the second sealant layer 16b using an extrusion laminator can be mentioned. Furthermore, the first sealant layer 16a and the second sealant layer 16b can also be laminated by a tandem lamination method or a co-extrusion method of extruding them. The resin composition for forming the first sealant layer 16a and the resin composition for forming the second sealant layer 16b can be prepared, for example, by blending each component so as to satisfy the configurations of the first sealant layer 16a and the second sealant layer 16b described above.

[0176] By this process, a laminate in which each layer is laminated in the order of the base material layer 11 / the first adhesive layer 12 / the barrier layer 13 / the corrosion prevention treatment layer 14 / the first sealant layer 16a / the second sealant layer 16b as shown in FIG. 2 is obtained.

[0177] Note that the first sealant layer 16a may be directly laminated by an extrusion laminator with the dry-blended material so as to have the material blending composition described above, or alternatively, the first sealant layer 16a granulated after melt blending using a melt kneading device such as a single-screw extruder, a twin-screw extruder, or a Brabender mixer in advance may be laminated using an extrusion laminator.

[0178] The second sealant layer 16b may be formed by directly laminating, using an extrusion laminator, the materials dry-blended so as to have the material blending composition described above as the resin composition for forming the sealant layer, or alternatively, by laminating, using a tandem lamination method or a co-extrusion method in which the extruded laminate is formed by extruding the first sealant layer 16a and the second sealant layer 16b with an extrusion laminator, the granulated product obtained after subjecting to melt blending using a melt kneading apparatus such as a single-screw extruder, a twin-screw extruder, or a Brabender mixer. Further, the sealant single film may be formed in advance as a cast film using the resin composition for forming the sealant layer, and the film may be laminated by a method of sand lamination together with an adhesive resin, or may be laminated by a dry lamination method using an adhesive agent.

[0179] (Heat treatment step) This step is a step of heat-treating the laminate. By heat-treating the laminate, the adhesion between the barrier layer 13 / the corrosion prevention treatment layer 14 / the first sealant layer 16a / the second sealant layer 16b can be improved. As a heat treatment method, it is preferable to perform the treatment at a temperature equal to or higher than the melting point of at least the first sealant layer 16a.

[0180] In this way, the exterior material 20 of the present embodiment as shown in FIG. 2 can be manufactured.

[0181] Next, an example of a method for manufacturing the exterior material 30 shown in FIG. 3 will be described. Note that the manufacturing method of the exterior material 30 is not limited to the following method.

[0182] The manufacturing method of the exterior material 30 of the present embodiment generally includes a step of laminating the corrosion prevention treatment layer 14 on the barrier layer 13, a step of bonding the base material layer 11 and the barrier layer 13, a step of further laminating the first sealant layer 16a, the third sealant layer 16c, and the second sealant layer 16b to produce a laminate, and a step of heat-treating the obtained laminate as necessary.

[0183] (Lamination step of the first sealant layer 16a, the third sealant layer 16c, and the second sealant layer 16b) This process is a process of forming a first sealant layer 16a, a third sealant layer 16c, and a second sealant layer 16b on the corrosion prevention treatment layer 14. As methods thereof, there are mentioned a tandem lamination method and a coextrusion method in which the first sealant layer 16a, the third sealant layer 16c, and the second sealant layer 16b are extruded using an extrusion laminator. In this case, the materials dry-blended so as to have the above-described material blending composition as the resin composition for forming the sealant layer may be directly laminated by an extrusion laminator, or alternatively, after subjecting to melt blending using a melt kneading device such as a single-screw extruder, a twin-screw extruder, or a Brabender mixer in advance, the granulated product may be laminated by a tandem lamination method or a coextrusion method in which the first sealant layer 16a, the third sealant layer 16c, and the second sealant layer 16b are extruded by an extrusion laminator.

[0184] The third sealant layer 16c and the second sealant layer 16b may be formed into films by coextrusion, and these films may be laminated by a method of sand lamination together with the resin composition for forming the first sealant layer 16a.

[0185] In this way, the exterior material 30 of the present embodiment as shown in FIG. 3 can be manufactured.

[0186] As described above, the preferred embodiments of the exterior material for all-solid-state batteries of the present disclosure have been described in detail. However, the present disclosure is not limited to such specific embodiments, and various modifications and changes are possible within the scope of the gist of the present disclosure described within the claims. For example, when manufacturing an exterior material for all-solid-state batteries that does not have the first adhesive layer 12, as described above, the base material layer 11 may be formed by applying or coating a resin material capable of forming the base material layer 11 on the barrier layer 13.

[0187] [All-solid-state battery] FIG. 4 is a perspective view showing an embodiment of an all-solid-state battery manufactured using the above-described exterior material. As shown in FIG. 4, the all-solid-state battery 50 includes a battery element 52, two metal terminals (current extraction terminals) 53 for extracting current from the battery element 52 to the outside, and an exterior material 10 that encloses the battery element 52 in an airtight state. The exterior material 10 is the exterior material 10 according to the present embodiment described above. In the exterior material 10, the base material layer 11 is the outermost layer, and the sealant layer 16 is the innermost layer. That is, the exterior material 10 is formed by folding one laminate film in half and heat-sealing it so that the base material layer 11 is on the outside of the all-solid-state battery 50 and the sealant layer 16 is on the inside of the all-solid-state battery 50, or by overlapping two laminate films and heat-sealing them, so as to include the battery element 52 inside. Note that, in the all-solid-state battery 50, the exterior material 20 or the exterior material 30 may be used instead of the exterior material 10.

[0188] The battery element 52 is formed by interposing a sulfide-based solid electrolyte between a positive electrode and a negative electrode. The metal terminal 53 is formed by taking out a part of the current collector to the outside of the exterior body 10 and is made of a metal foil such as a copper foil or an aluminum foil. In the all-solid-state battery 50 of the present embodiment, even when hydrogen sulfide is generated from the battery element 52, the exterior material 10 can detoxify the hydrogen sulfide, so that corrosion of the metal terminal (current collector) 53 inside the exterior material 10 can be suppressed, and even when the exterior material 10 is damaged, leakage of hydrogen sulfide to the outside can be suppressed, and excellent safety can be ensured.

Example

[0189] Hereinafter, the present disclosure will be described more specifically based on examples, but the present disclosure is not limited to the following examples.

[0190] [Materials Used] The materials used in the examples and comparative examples are shown below. <Base Material Layer (Thickness: 15 μm)> A nylon (Ny) film (manufactured by Toyobo Co., Ltd.) was used.

[0191] <First Adhesive Layer (Thickness: 4 μm)> A polyurethane adhesive (manufactured by Toyo Ink Co., Ltd.) was used, which was prepared by blending an adduct-based curing agent of tolylene diisocyanate with a polyester polyol-based main agent.

[0192] <The first corrosion prevention treatment layer (substrate layer side) and the second corrosion prevention treatment layer (sealant layer side)> (CL-1): "Sodium polyphosphate-stabilized cerium oxide sol" adjusted to a solid content concentration of 10% by mass using distilled water as a solvent was used. The sodium polyphosphate-stabilized cerium oxide sol was obtained by blending 10 parts by mass of the Na salt of phosphoric acid with respect to 100 parts by mass of cerium oxide. (CL-2): A composition consisting of 90% by mass of "polyallylamine (manufactured by Nitto Boseki Co., Ltd.)" adjusted to a solid content concentration of 5% by mass using distilled water as a solvent and 10% by mass of "polyglycerol polyglycidyl ether (manufactured by Nagase ChemteX Corporation)" was used.

[0193] <Barrier layer (thickness: 35 μm)> Annealed and degreased soft aluminum foil (manufactured by Toyo Aluminum Co., Ltd., "8079 material") was used.

[0194] <Second adhesive layer (thickness: 3 μm)> As adhesives for forming the second adhesive layer, the following adhesives a and b were prepared. Adhesive a: An adhesive prepared by blending 10 parts by mass (solid content ratio) of a polyisocyanate compound having an isocyanurate structure with respect to 100 parts by mass of an acid-modified polyolefin resin dissolved in toluene. Adhesive b: A polyurethane adhesive prepared by blending a polyester polyol composed of hydrogenated dimer fatty acid and diol and a polyisocyanate so that the molar ratio (NCO / OH) is 2.

[0195] <Sealant layer> [Resin composition for forming the sealant layer] As constituent materials for the resin composition for forming a sealant layer, the following base resin, compatibilizing elastomer, ionomer, LDPE, and compatibilizers a and b were prepared. These materials were blended at the mass ratios shown in Table 1 to obtain a resin composition for forming a sealant layer.

[0196] Base resin: Propylene-ethylene random copolymer (random PP). Compatibilizing elastomer: Propylene-butene-1 random copolymer elastomer (propylene-butene-1) having compatibility with the base resin. Ionomer: An ionomer resin in which the intermolecular spaces of an ethylene-α,β-unsaturated carboxylic acid copolymer are crosslinked with zinc ions. LDPE: Low-density polyethylene (manufactured by Nippon Polyethylene Co., Ltd., "LC600A"). Compatibilizer a: A block copolymer composed of propylene units and ethylene units. Compatibilizer b: A block copolymer composed of crystalline ethylene units and ethylene-butylene units.

[0197] [Examples 1 to 13 and Comparative Examples 1 to 3] First, first and second corrosion prevention treatment layers were provided on the barrier layer by the following procedure. That is, (CL-1) was applied to both surfaces of the barrier layer by microgravure coating so that the dry coating amount was 70 mg / m 2 and baked at 200 °C in a drying unit. Next, (CL-2) was applied to the obtained layer by microgravure coating so that the dry coating amount was 20 mg / m 2 to form a composite layer composed of (CL-1) and (CL-2) as the first and second corrosion prevention treatment layers. This composite layer exhibits corrosion prevention performance by compounding two types of (CL-1) and (CL-2).

[0198] Next, the side of the first corrosion prevention treatment layer of the barrier layer provided with the first and second corrosion prevention treatment layers was attached to the base material layer using a polyurethane-based adhesive (first adhesive layer) by a dry lamination method. Next, the side of the second corrosion prevention treatment layer of the barrier layer provided with the first and second corrosion prevention treatment layers was attached to a sealant layer (thickness: 30 μm) previously formed as a cast film using the adhesive a or b (second adhesive layer) shown in Table 1 by a dry lamination method. For forming the sealant layer, a resin composition for forming a sealant layer having the composition shown in Table 1 was used.

[0199] The laminate thus obtained was subjected to an aging treatment at 40°C for 4 days to produce the exterior material of Example 7 (a laminate of a base material layer / first adhesive layer / first corrosion prevention treatment layer / barrier layer / second corrosion prevention treatment layer / second adhesive layer / sealant layer).

[0200] [Example 14] In the same manner as in Example 1, a first and a second corrosion prevention treatment layer were provided on the barrier layer. The side of the first corrosion prevention treatment layer of the barrier layer provided with the first and second corrosion prevention treatment layers was attached to the base material layer using a polyurethane-based adhesive (first adhesive layer) by a dry lamination method. This was set at the unwinding part of an extrusion laminator, and the sealant layer (thickness: 30 μm) was laminated by co-extruding the material of the sealant layer on the second corrosion prevention treatment layer under the processing conditions of 290°C and 100 m / min. The sealant layer was prepared by previously compounding various materials using a twin-screw extruder, passing through a water-cooling and pelletizing process, and then used for the above extrusion lamination. For forming the sealant layer, a resin composition for forming a sealant layer having the composition shown in Table 1 was used.

[0201] The laminate thus obtained was heat-treated so that the maximum temperature reached by the laminate was 190°C to produce the exterior material of Example 14 (a laminate of a base material layer / first adhesive layer / first corrosion prevention treatment layer / barrier layer / second corrosion prevention treatment layer / sealant layer).

[0202] [Example 15] In the same manner as in Example 1, first and second corrosion prevention treatment layers were provided on the barrier layer. The side of the barrier layer provided with the first and second corrosion prevention treatment layers on the first corrosion prevention treatment layer side was attached to the base material layer using a polyurethane-based adhesive (first adhesive layer) by a dry lamination method. Next, the side of the barrier layer provided with the first and second corrosion prevention treatment layers on the second corrosion prevention treatment layer side was attached to a sealant layer (thickness: 30 μm) previously formed as a cast film using adhesive a (second adhesive layer) by a dry lamination method. The sealant layer was formed as a laminated film of a metal foil side layer (hereinafter also referred to as "AL side layer") (thickness: 15 μm) and an innermost layer (thickness: 15 μm) by co-extruding two types of resin compositions for forming the sealant layer having the compositions shown in Table 2.

[0203] [Example 16] In the same manner as in Example 1, first and second corrosion prevention treatment layers were provided on the barrier layer. The side of the barrier layer provided with the first and second corrosion prevention treatment layers on the first corrosion prevention treatment layer side was attached to the base material layer using a polyurethane-based adhesive (first adhesive layer) by a dry lamination method. This was set at the unwinding part of an extrusion laminator, and by co-extruding the material of the sealant layer on the second corrosion prevention treatment layer under the processing conditions of 290°C and 100 m / min, a metal foil side layer (hereinafter also referred to as "AL side layer") (thickness: 15 μm) and an innermost layer (thickness: 15 μm) were laminated in this order as the sealant layer. The AL side layer and the innermost layer were previously prepared by compounding various materials using a twin-screw extruder, and after passing through a water cooling and pelletizing process, they were used for the above extrusion lamination. For the formation of the AL side layer and the innermost layer, a resin composition for forming the sealant layer having the compositions shown in Table 2 was used.

[0204] The laminate thus obtained was heat-treated so that the maximum temperature reached by the laminate was 190°C to produce the exterior material of Example 16 (a laminate of a base material layer / first adhesive layer / first corrosion prevention treatment layer / barrier layer / second corrosion prevention treatment layer / sealant layer (AL side layer) / sealant layer (innermost layer)).

[0205]

Table 1

[0206]

Table 2

[0207] <Evaluation> The following evaluation tests were conducted on the exterior materials obtained in the examples and comparative examples.

[0208] (Heat seal strength) Two samples of the exterior material cut into 60 mm × 120 mm were folded, and one side was heat-sealed at 190 °C, 0.5 MPa, and for 3 seconds with a seal bar having a width of 10 mm. After storing the heat-sealed exterior material at room temperature (25 °C) for 24 hours, the heat-sealed portion was cut to a width of 15 mm (see Fig. 5), and the seal strength (T-peel strength) was measured using a testing machine (manufactured by INSTRON). The test was carried out at 23 °C and 50% RH atmosphere with a peeling speed of 50 mm / min in accordance with JIS K6854. The measurement results are shown in Table 3. A seal strength of 30 N / 15 mm or more is considered qualified.

[0209] (Corrosion evaluation) A sample 40 with the exterior material cut into 120 mm × 200 mm was set in a cold-forming die such that the sealant layer was in contact with the convex part of the forming machine, and a deep drawing with a depth of 2.0 mm was performed at a forming speed of 15 mm / sec to form a deep-drawn part 41. After that, it was folded in two to 120 mm × 100 mm (see Fig. 6(a)). A die with a forming area of 80 mm × 70 mm (square tube type) and a punch corner radius (RCP) of 1.0 mm was used. Next, after heat-sealing the upper side part 44 of 100 mm with a copper foil tab 42 and a tab sealant 43 sandwiched therebetween (see Fig. 6(b)), the side part 45 of 120 mm was heat-sealed to form a bag (see Fig. 6(c)). Then, 5 ml of hydrogen sulfide gas at 1 mass ppm was injected from the remaining unsealed side (see Fig. 6(d)), and the lower side part 46 of 100 mm was sealed by heat-sealing (see Fig. 6(e)). Then, this pouch was stored in a constant-temperature bath at 40°C for one month, and the corrosion status of the copper foil tab 42 inside the pouch after opening was visually confirmed. When any of discoloration, mottling, rust, or dendrite occurred on the copper foil tab 42, it was determined as "B" (corrosion present), and when none of them occurred, it was determined as "A" (corrosion absent). The results are shown in Table 3.

[0210]

Table 3

Explanation of Symbols

[0211] 10, 20, 30… Exterior materials for all-solid-state batteries, 11… Base material layer, 12… First adhesive layer, 13… Barrier layer, 14… Corrosion prevention treatment layer, 16… Sealant layer, 16a… First sealant layer, 16b… Second sealant layer, 16c… Third sealant layer, 17… Second adhesive layer, 40… Sample, 41… Deep-drawn part, 42… Copper foil tab, 43… Tab sealant, 44… Upper side part, 45… Side part, 46… Lower side part, 50… All-solid-state battery, 52… Battery element, 53… Metal terminal.

Claims

1. An exterior material for an all-solid-state battery containing a sulfide-based solid electrolyte, comprising at least a base layer, a barrier layer, and a sealant layer in this order, wherein the sealant layer comprises a mixed resin layer containing an ionomer and a base resin composition other than the ionomer, and the base resin composition is a resin composition containing a base resin and a compatibilizing elastomer having compatibility with the base resin. An exterior material for an all-solid-state battery.

2. The exterior material for an all-solid-state battery according to claim 1, wherein the base resin composition contains (A) 60 to 95% by mass of a propylene-ethylene random copolymer and (B) 5 to 40% by mass of a polyolefin-based elastomer having a melting point of 150°C or lower and having butene-1 as a comonomer.

3. The exterior material for an all-solid-state battery according to claim 1 or 2, wherein the mixed resin layer further contains a compatibilizer having a part compatible with the resin contained in the base resin composition and a part compatible with the ionomer.

4. The exterior material for an all-solid-state battery according to any one of claims 1 to 3, wherein the ionomer contains an ethylene-based ionomer resin.

5. The exterior material for an all-solid-state battery according to any one of claims 1 to 4, wherein the metal ion forming the ionomer contains zinc ions.

6. The exterior material for an all-solid-state battery according to any one of claims 1 to 5, wherein the mixed resin layer contains a polypropylene-based resin and an ethylene-based ionomer resin that is incompatible with the polypropylene-based resin as the ionomer.

7. The exterior material for an all-solid-state battery according to claim 6, wherein the mixed resin layer further contains a compatibilizer having a part compatible with the polypropylene-based resin and a part compatible with the ethylene-based ionomer resin.

8. The exterior material for an all-solid-state battery according to any one of claims 1 to 7, wherein the content of the ionomer in the mixed resin layer is 1 to 40% by mass based on the total solid content of the mixed resin layer.

9. The exterior material for an all-solid-state battery according to any one of claims 1 to 8, wherein the sealant layer is composed of a plurality of layers, at least one of which is a layer containing the ionomer, and at least one of the other layers is a layer containing a polypropylene-based resin, and one of the layer containing the ionomer and the layer containing the polypropylene-based resin is the mixed resin layer.

10. The exterior material for an all-solid-state battery according to any one of claims 1 to 9, wherein a corrosion prevention treatment layer is provided on one or both surfaces of the barrier layer.

11. The exterior material for an all-solid-state battery according to claim 10, wherein the corrosion prevention treatment layer contains cerium oxide, 1 to 100 parts by mass of phosphoric acid or phosphate based on 100 parts by mass of the cerium oxide, and a cationic polymer.

12. A battery element containing a sulfide-based solid electrolyte, A current extraction terminal extending from the battery element, The exterior material for an all-solid-state battery according to any one of claims 1 to 11, which sandwiches the current extraction terminal and houses the battery element, An all-solid-state battery comprising the same.

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