Exterior material for all-solid-state battery and all-solid

Abstract

To provide a sheath material for an all-solid-state battery capable of suppressing generation of bubbles in a sealant layer during heat sealing, and an all-solid-state battery.SOLUTION: A packaging material for an all-solid-state battery comprising at least a substrate layer, a barrier layer, and a sealant layer in this order, wherein a moisture content of the sealant layer is 2700 ppm by mass or less. The sealant layer is composed of, for example, a polyolefin film containing a polyolefin-based resin or a polyester film containing a polyester-based resin.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an exterior material for an all-solid-state battery and an all-solid-state battery. [Background technology]

[0002] In recent years, the development of all-solid-state batteries that can achieve large capacities has progressed rapidly. Unlike current lithium-ion batteries, all-solid-state batteries have a solid electrolyte, which allows them to be used at high temperatures that were previously unachievable. This eliminates the need for battery cooling equipment, and is expected to lead to improved space efficiency, reduced costs, and lower power consumption.

[0003] Such an all-solid-state battery includes a battery body containing a solid electrolyte and electrodes, and an outer bag for housing the battery body. The outer bag is obtained by heat-sealing an outer packaging material. The outer packaging material for such an all-solid-state battery includes a base layer, a barrier layer, and a sealant layer in this order. The sealant layer is made of a polyester film or the like to provide heat resistance (see, for example, Patent Document 1 below). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6747636 (e.g., claim 5) Summary of the Invention [Problem to be solved by the invention]

[0005] However, the exterior packaging material for the all-solid-state battery described in Patent Document 1 has the following problems. That is, in the case of the exterior packaging material of the all-solid-state battery described in Patent Document 1, bubbles were sometimes observed all over the sealant layer during heat sealing.

[0006] The present disclosure has been made in view of the above-described problems, and aims to provide an exterior packaging material for an all-solid-state battery that can suppress the generation of bubbles in a sealant layer during heat sealing, and an all-solid-state battery using the same. [Means for solving the problem]

[0007] The present inventors investigated the cause of the phenomenon of bubbles appearing throughout the sealant layer as described above. As a result, they concluded that the occurrence of bubbles throughout the sealant layer may be due to the heat-sealing of the packaging material at high temperatures. Specifically, the present inventors hypothesized that when the packaging material is heat-sealed at high temperatures, the moisture in the sealant layer of the packaging material evaporates, causing the resulting bubbles to expand rapidly, easily combine with other bubbles, grow, and remain after cooling. The present inventors also hypothesized that the phenomenon may be significantly dependent on the moisture content of the sealant layer of the packaging material. Therefore, the present inventors conducted further intensive research and discovered that the above-mentioned problem can be solved by the following disclosure.

[0008] That is, the present disclosure provides an exterior material for an all-solid-state battery, which includes at least a substrate layer, a barrier layer, and a sealant layer in this order, and the water content of the sealant layer is 2700 ppm by mass or less.

[0009] The packaging material of the present disclosure can suppress the generation of bubbles in the sealant layer during heat sealing. This prevents the sealant layer from having coarse portions (portions with many bubbles) and dense portions (portions with few bubbles), which would otherwise cause a decrease in seal strength at the coarse portions. Therefore, even if the battery body containing a solid electrolyte expands during use of an all-solid-state battery in a high-temperature environment, exerting a force that attempts to open the packaging bag, the packaging material can maintain the sealed state of the packaging bag obtained by heat sealing the packaging material. Therefore, even if a gas such as hydrogen sulfide is generated in the packaging bag of an all-solid-state battery that contains a sulfide-based solid electrolyte as the solid electrolyte, due to a reaction between moisture and the sulfide-based solid electrolyte, leakage of such gas can be suppressed. Furthermore, since the generation of bubbles that easily serve as a moisture passageway is suppressed in the sealant layer, the intrusion of moisture from outside the packaging material is suppressed. Therefore, even if a gas such as hydrogen sulfide is generated in the packaging bag of an all-solid-state battery that contains a sulfide-based solid electrolyte as the solid electrolyte, due to a reaction between moisture and the sulfide-based solid electrolyte, it is also possible to suppress the generation of gas such as hydrogen sulfide in the packaging bag of an all-solid-state battery.

[0010] In the all-solid-state battery packaging material, the sealant layer is preferably a polyolefin film containing a polyolefin-based resin or a polyester film containing a polyester-based resin.

[0011] In this case, the sealing property is improved. Furthermore, since the polyolefin film and the polyester film have heat resistance, the exterior material can further improve the heat resistance of the all-solid-state battery.

[0012] In the all-solid-state battery packaging material, it is preferable that the sealant layer is the polyolefin film, the polyolefin film includes an acid-modified polyolefin resin layer, and the acid-modified polyolefin resin layer is directly laminated to the barrier layer.

[0013] In this case, moisture is less likely to be trapped in the sealant layer than when the acid-modified polyolefin resin layer of the polyolefin film is directly laminated to the barrier layer and the acid-modified polyolefin resin layer of the polyolefin film and the barrier layer are bonded together with a polyurethane-based adhesive, which is used as a high-temperature resistant adhesive. Therefore, even if the packaging material is repeatedly exposed to high temperatures, moisture is less likely to be released from the sealant layer each time. Therefore, when an all-solid-state battery contains a sulfide-based solid electrolyte as a solid electrolyte in an packaging bag, the generation of hydrogen sulfide due to a reaction between the released moisture and sulfide can be suppressed.

[0014] In the all-solid-state battery packaging material, the sealant layer preferably has a melting point of 250° C. or lower.

[0015] In this case, since the sealant layer has a melting point of 250°C or less, the heat sealing temperature can be reduced. Therefore, the generation of bubbles in the sealant layer during heat sealing can be further suppressed. Therefore, the deterioration of the seal strength and barrier properties of the packaging material can be further suppressed. Therefore, the packaging material can more sufficiently maintain the hermeticity of the packaging bag for the all-solid-state battery.

[0016] In the all-solid-state battery packaging material, the sealant layer preferably has a melting point of 150° C. or higher.

[0017] In this case, since the sealant layer has a melting point of 150° C. or higher, it is possible to prevent a decrease in the sealing strength of the exterior material even when the exterior material is used in a high-temperature environment. Therefore, when an all-solid-state battery contains a sulfide-based solid electrolyte as a solid electrolyte in an exterior bag, even if gases such as hydrogen sulfide are generated by a reaction between moisture and the sulfide-based solid electrolyte in the exterior bag of the all-solid-state battery, leakage of such gases can be further prevented.

[0018] The present disclosure also provides an all-solid-state battery including a battery body having a solid electrolyte and an outer bag that houses the battery body, the outer bag being obtained by heat-sealing the above-described outer packaging material for an all-solid-state battery.

[0019] According to the all-solid-state battery of the present disclosure, an outer bag is obtained by heat-sealing the above-described all-solid-state battery exterior material. Here, the above-described exterior material can suppress the generation of air bubbles in the sealant layer during heat sealing. Therefore, the all-solid-state battery of the present disclosure suppresses the occurrence of rough and dense portions in the sealant layer of the exterior material, which would otherwise cause a decrease in seal strength at the rough portions. Therefore, even if the battery body expands during use of the all-solid-state battery in a high-temperature environment, exerting a force that attempts to open the exterior bag, the exterior material can maintain the sealed state of the exterior bag of the all-solid-state battery. Furthermore, since the generation of air bubbles in the sealant layer, which can easily serve as a moisture passageway, is suppressed, the intrusion of moisture from outside the exterior material is suppressed. Therefore, when a sulfide-based solid electrolyte is used as the solid electrolyte, it is also possible to suppress the generation of gases such as hydrogen sulfide due to a reaction between moisture and the sulfide-based solid electrolyte within the exterior bag of the all-solid-state battery.

[0020] In the present disclosure, "melting point" means the "peak melting temperature" determined in accordance with the method described in JIS K7121-1987, and when two or more independent melting peaks appear, the lowest peak melting temperature is used.

[0021] In addition, in the present disclosure, when the sealant layer is a multilayer film, the melting point refers to the melting point of the layer that has the lowest melting point among the layers that make up the multilayer film. [Effects of the Invention]

[0022] According to the present disclosure, there are provided an exterior packaging material for an all-solid-state battery that can suppress the generation of bubbles in a sealant layer during heat sealing, and an all-solid-state battery using the same. [Brief explanation of the drawings]

[0023] [Figure 1]FIG. 1 is a cross-sectional view schematically illustrating an exterior packaging material for an all-solid-state battery according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a cross-sectional view schematically showing an exterior material for an all-solid-state battery according to another embodiment of the present disclosure. [Figure 3] FIG. 10 is a cross-sectional view schematically showing an exterior material for an all-solid-state battery according to still another embodiment of the present disclosure. [Figure 4] FIG. 1 is a perspective view showing an all-solid-state battery according to an embodiment of the present disclosure. [Figure 5] FIG. 2 is a plan view showing a structure for obtaining evaluation samples in Examples and Comparative Examples. DETAILED DESCRIPTION OF THE INVENTION

[0024] Preferred embodiments of the present disclosure will be described in detail below with reference to the drawings. In the drawings, identical or corresponding parts are designated by the same reference numerals, and duplicate explanations will be omitted. Furthermore, the dimensional ratios of the drawings are not limited to those shown.

[0025] [Exterior material for all-solid-state batteries] Fig. 1 is a cross-sectional view schematically illustrating an all-solid-state battery exterior packaging material according to one embodiment of the present disclosure. As shown in Fig. 1, an all-solid-state battery exterior packaging material 10 according to this embodiment (hereinafter also simply referred to as "exterior packaging material") includes, in this order, a base layer 11, a first adhesive layer 12a, a barrier layer 13, a second adhesive layer 12b, and a sealant layer 16. The water content of the sealant layer 16 is 2700 ppm by mass or less. When the exterior packaging material 10 is heat-sealed, the generation of bubbles in the sealant layer 16 of the exterior packaging material 10 can be more effectively suppressed than when the water content of the sealant layer 16 exceeds 2700 ppm by mass.

[0026] The barrier layer 13 may have a first corrosion prevention treatment layer 14a on the substrate layer 11 side. The barrier layer 13 may have a second corrosion prevention treatment layer 14b on the sealant layer 16 side. In the packaging material 10, the substrate layer 11 is the outermost layer, and the sealant layer 16 is the innermost layer. That is, the packaging material 10 is used with the substrate layer 11 facing the exterior side of the all-solid-state battery and the sealant layer 16 facing the interior side of the all-solid-state battery.

[0027] Each layer that constitutes the packaging material 10 will be described in detail below.

[0028] <Base material layer> The base material layer 11 provides heat resistance in the sealing process when manufacturing an all-solid-state battery and plays a role in suppressing the occurrence of pinholes that may occur during molding, processing, and distribution. In particular, in the case of an exterior material for a large-scale all-solid-state battery, the base material layer 11 can also provide scratch resistance, chemical resistance, insulating properties, and the like.

[0029] The base layer 11 is preferably a layer formed of an insulating resin, such as polyester resin, polyamide resin, polyimide resin, polyamideimide resin, polyetherketone resin, polyphenylene sulfide resin, polyetherimide resin, polysulfone resin, fluororesin, phenol resin, melamine resin, urethane resin, allyl resin, silicone resin, epoxy resin, furan resin, or acetyl cellulose resin.

[0030] When these resins are applied to the substrate layer 11, they may be in the form of a stretched or unstretched film, or in the form of a coating film. The substrate layer 11 may be a single layer or a multilayer, and in the case of a multilayer, different resins may be used in combination. In the case of a film, a co-extruded film or a film laminated with an adhesive may be used. In the case of a coating film, a film coated with the number of layers may be used, and a multilayer film may also be formed by combining a film and a coating film.

[0031] Among these resins, polyester resins and polyamide resins are preferred for the base layer 11 because of their excellent moldability. Examples of polyester resins include polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate. Examples of polyamide resins include nylon 6, nylon 6,6, a copolymer of nylon 6 and nylon 6,6, nylon 6, nylon 9T, nylon 10, polymetaxylylene adipamide (MXD6), nylon 11, and nylon 12.

[0032] When these resins are used in the form of a film, a biaxially stretched film is preferred. Examples of stretching methods for biaxially stretched films include sequential biaxial stretching, tubular biaxial stretching, and simultaneous biaxial stretching. From the viewpoint of obtaining better deep drawability, the biaxially stretched film is preferably one stretched by the tubular biaxial stretching method.

[0033] The thickness of the substrate layer 11 is preferably 6 to 50 μm, and more preferably 10 to 30 μm. When the thickness of the substrate layer 11 is 6 μm or more, the pinhole resistance and insulating properties of the packaging material 10 tend to be improved. When the thickness of the substrate layer 11 is 50 μm or less, the total thickness of the packaging material 10 can be reduced.

[0034] The melting point of the base layer 11 is higher than that of the sealant layer 16, preferably 30° C. or more higher than that of the sealant layer 16, in order to suppress deformation of the base layer 11 during sealing.

[0035] <First adhesive layer> The first adhesive layer 12a is a layer that bonds the base material layer 11 and the barrier layer 13. Specific examples of materials that constitute the first adhesive layer 12a include polyurethane resins in which a bifunctional or higher isocyanate compound (a polyfunctional isocyanate compound) is reacted with a base material such as polyester polyol, polyether polyol, acrylic polyol, or carbonate polyol. The various polyols described above can be used alone or in combination of two or more types depending on the functions and performance required of the packaging material 10. In addition to the above, a material that uses an epoxy resin as a base material and a curing agent can also be used, but is not limited to this. Furthermore, various other additives and stabilizers may be blended into the above adhesive depending on the performance required of the adhesive.

[0036] The thickness of the first adhesive layer 12a is not particularly limited, but from the viewpoint of obtaining the desired adhesive strength, conformability, processability, etc., it is preferably, for example, 1 to 10 μm, more preferably 2 to 7 μm.

[0037] <Barrier layer> The barrier layer 13 has water vapor barrier properties that prevent moisture from penetrating into the interior of the all-solid-state battery. The barrier layer 13 may also have extensibility for deep drawing. Examples of the barrier layer 13 that can be used include various metal foils such as aluminum, stainless steel, and copper, as well as metal vapor-deposited films, inorganic oxide vapor-deposited films, carbon-containing inorganic oxide vapor-deposited films, and films having these vapor-deposited films. Examples of films having vapor-deposited films that can be used include aluminum vapor-deposited films and inorganic oxide vapor-deposited films. These may be used alone or in combination of two or more. In terms of mass (specific gravity), moisture resistance, processability, and cost, metal foils are preferred for the barrier layer 13, and aluminum foil is more preferred.

[0038] As the aluminum foil, soft aluminum foil that has been annealed is particularly preferred because it can impart the desired ductility during molding. However, it is more preferable to use aluminum foil containing iron for the purpose of imparting further pinhole resistance and ductility during molding. The iron content in the aluminum foil is preferably 0.1 to 9.0 mass%, more preferably 0.5 to 2.0 mass%, based on 100 mass% of the aluminum foil. By having an iron content of 0.1 mass% or more, an exterior packaging material 10 having better pinhole resistance and ductility can be obtained. By having an iron content of 9.0 mass% or less, an exterior packaging material 10 having better flexibility can be obtained. As the aluminum foil, untreated aluminum foil may be used, but it is preferable to use aluminum foil that has been degreased in order to impart corrosion resistance. When the aluminum foil is degreased, the degreasing treatment may be performed on only one side of the aluminum foil, or on both sides.

[0039] The thickness of the barrier layer 13 is not particularly limited, but is preferably 9 to 200 μm, more preferably 15 to 100 μm, in consideration of barrier properties, pinhole resistance, and processability.

[0040] <First and second corrosion prevention treatment layers> The first and second corrosion prevention treatment layers 14a, 14b are layers provided to prevent corrosion of the metal foil (metal foil layer) that constitutes the barrier layer 13. The first corrosion prevention treatment layer 14a serves to increase the adhesion between the barrier layer 13 and the first adhesive layer 12a. The second corrosion prevention treatment layer 14b serves to increase the adhesion between the barrier layer 13 and the second adhesive layer 12b. The first corrosion prevention treatment layer 14a and the second corrosion prevention treatment layer 14b may be layers of the same configuration or layers of different configurations. The first and second corrosion prevention treatment layers 14a, 14b (hereinafter simply referred to as "corrosion prevention treatment layers 14a, 14b") are formed, for example, by degreasing, hydrothermal conversion treatment, anodizing, chemical conversion treatment, or a combination of these treatments.

[0041] Examples of degreasing treatments include acid degreasing and alkaline degreasing. Examples of acid degreasing include a method using an inorganic acid such as sulfuric acid, nitric acid, hydrochloric acid, or hydrofluoric acid, either alone or in combination. Furthermore, by using an acid degreasing agent prepared by dissolving a fluorine-containing compound such as monosodium ammonium difluoride in the inorganic acid, not only can the aluminum be degreased, but also a passive aluminum fluoride can be formed, which is effective in terms of corrosion resistance, particularly when an aluminum foil is used for the barrier layer 13. Examples of alkaline degreasing include a method using sodium hydroxide or the like.

[0042] An example of the hydrothermal modification treatment is boehmite treatment, in which aluminum foil is immersed in boiling water containing triethanolamine. An example of the anodization treatment is alumite treatment.

[0043] The chemical conversion treatment may be an immersion type or a 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, and various chemical conversion treatments consisting of a mixture of these. On the other hand, an example of the coating type chemical conversion treatment is a method in which a coating agent having corrosion prevention properties is applied to the barrier layer 13.

[0044] When forming at least a part of the corrosion prevention treatment layer by any of these corrosion prevention treatments, i.e., hydrothermal conversion treatment, anodizing treatment, or chemical conversion treatment, it is preferable to perform the degreasing treatment described above beforehand. Note that when a degreased metal foil, such as a metal foil that has been subjected to an annealing process, is used as the barrier layer 13, there is no need to perform a degreasing treatment again when forming the corrosion prevention treatment layers 14a and 14b.

[0045] The coating agent used in the spray-type chemical conversion treatment preferably contains trivalent chromium and may also contain at least one polymer selected from the group consisting of cationic polymers and anionic polymers, which will be described later.

[0046] Among the above treatments, hydrothermal conversion treatment and anodizing, in particular, dissolve the aluminum foil surface with a treatment agent to form aluminum compounds (boehmite, anodized aluminum) with excellent corrosion resistance. Therefore, a bicontinuous structure is formed from the aluminum foil barrier layer 13 to the corrosion prevention treatment layers 14a, 14b, and these treatments are included in the definition of chemical conversion treatment. On the other hand, as described below, it is also possible to form the corrosion prevention treatment layers 14a, 14b using a pure coating method, which is not included in the definition of chemical conversion treatment. One example of such a method is the use of a sol of a rare earth oxide, such as cerium oxide, with an average particle size of 100 nm or less, which has an aluminum corrosion prevention effect (inhibitor effect) and is environmentally friendly. Using this method, it is possible to impart corrosion prevention effects to metal foils such as aluminum foil using a conventional coating method.

[0047] Examples of the rare earth element oxide sol include sols using various solvents such as water-based, alcohol-based, hydrocarbon-based, ketone-based, ester-based, ether-based, etc. Of these, water-based sols are preferred.

[0048] In order to stabilize the dispersion of the rare earth element oxide sol, inorganic acids such as nitric acid, hydrochloric acid, phosphoric acid, or their salts, or organic acids such as acetic acid, malic acid, ascorbic acid, and lactic acid are usually used as dispersion stabilizers. Of these dispersion stabilizers, phosphoric acid in particular is expected to have the following effects on the exterior packaging material 10: (1) stabilizing the dispersion of the sol, (2) improving adhesion to the barrier layer 13 by utilizing the aluminum chelating ability of phosphoric acid, (3) imparting corrosion resistance by capturing aluminum ions (passivation formation), and (4) improving the cohesion of the corrosion prevention treatment layers (oxide layers) 14a, 14b by easily causing dehydration condensation of phosphoric acid even at low temperatures.

[0049] Since the corrosion prevention treatment layers 14a, 14b formed from the rare earth element oxide sol are aggregates of inorganic particles, the cohesive strength of the layers themselves may be reduced even after the dry-cure process. Therefore, in this case, the corrosion prevention treatment layers 14a, 14b are preferably compounded with an anionic polymer or a cationic polymer to compensate for the cohesive strength.

[0050] The corrosion prevention treatment layers 14a, 14b are not limited to the layers described above. For example, they may be formed using a treatment agent that combines phosphoric acid and a chromium compound with a resin binder (such as aminophenol), as in the case of a known paint-type chromate. Using this treatment agent makes it possible to obtain a layer that combines both corrosion prevention functionality and adhesion. Furthermore, although the stability of the coating liquid must be considered, a coating agent that combines a rare earth element oxide sol with a polycationic polymer or a polyanionic polymer in advance as a one-component can be used to obtain a layer that combines corrosion prevention functionality and adhesion.

[0051] The mass per unit area of ​​the corrosion prevention treatment layers 14a and 14b is 0.005 to 0.200 g / m 2 regardless of whether the layer has a multi-layer structure or a single-layer structure. 2 is preferable, and 0.010 to 0.100 g / m 2 It is more preferable that the mass per unit area is 0.005 g / m 2 If the mass per unit area is 0.200 g / m or more, it is easy to impart a corrosion prevention function to the barrier layer 13. 2 Even if the thickness exceeds this range, the corrosion prevention function does not change significantly. On the other hand, when a rare earth element oxide sol is used, if the coating is thick, the heat curing during drying may be insufficient, which may result in a decrease in cohesive force. The thickness of the corrosion prevention treatment layers 14a and 14b can be calculated from their specific gravity.

[0052] From the viewpoint of making it easier to maintain adhesion between the sealant layer 16 and the barrier layer 13, the corrosion prevention treatment layers 14a, 14b may be in an embodiment containing, for example, cerium oxide, 1 to 100 parts by mass of phosphoric acid or a phosphate salt per 100 parts by mass of the cerium oxide, and a cationic polymer, or may be formed by subjecting the barrier layer 13 to a chemical conversion treatment, or may be formed by subjecting the barrier layer 13 to a chemical conversion treatment and contain a cationic polymer.

[0053] <Second adhesive layer> The second adhesive layer 12b is a layer that bonds the barrier layer 13 and the sealant layer 16. A general adhesive for bonding the barrier layer 13 and the sealant layer 16 can be used for the second adhesive layer 12b.

[0054] When a second corrosion prevention treatment layer 14b is provided on the barrier layer 13 and the second corrosion prevention treatment layer 14b has a layer containing at least one polymer selected from the group consisting of the above-mentioned cationic polymers and anionic polymers, the second adhesive layer 12b is preferably a layer containing a compound (hereinafter also referred to as a "reactive compound") that is reactive with the above-mentioned polymer contained in the second corrosion prevention treatment layer 14b.

[0055] For example, if the second corrosion prevention treatment layer 14b contains a cationic polymer, the second adhesive layer 12b contains a compound reactive with the cationic polymer. If the second corrosion prevention treatment layer 14b contains an anionic polymer, the second adhesive layer 12b contains a compound reactive with the anionic polymer. If the second corrosion prevention treatment layer 14b contains both a cationic polymer and an anionic polymer, the second adhesive layer 12b contains a compound reactive with the cationic polymer and a compound reactive with the anionic polymer. However, the second adhesive layer 12b does not necessarily have to contain both of these compounds; it may also contain a compound reactive with both the cationic polymer and the anionic polymer. Here, "reactive" means forming a covalent bond with the cationic polymer or the anionic polymer. The second adhesive layer 12b may also contain an acid-modified polyolefin resin.

[0056] The compound reactive with the cationic polymer may be at least one compound selected from the group consisting of a polyfunctional isocyanate compound, a glycidyl compound, a compound having a carboxy group, and a compound having an oxazoline group.

[0057] 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 from a cationic polymer. Among these, polyfunctional isocyanate compounds are preferred because they have high reactivity with cationic polymers and are easy to form a crosslinked structure.

[0058] The compound reactive with anionic polymers includes at least one compound selected from the group consisting of glycidyl compounds and compounds having an oxazoline group. 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 in cationic polymers. Among these, glycidyl compounds are preferred because of their high reactivity with anionic polymers.

[0059] When the second adhesive layer 12b contains an acid-modified polyolefin resin, the reactive compound preferably also has reactivity with the acidic groups in the acid-modified polyolefin resin (i.e., forms a covalent bond with the acidic groups). This further enhances adhesion to the second corrosion prevention treatment layer 14b. In addition, the acid-modified polyolefin resin forms a crosslinked structure, further improving the solvent resistance of the exterior packaging material 10.

[0060] The content of the reactive compound is preferably from 1 to 10 times the amount of the acidic groups in the acid-modified polyolefin resin. If the content of the reactive compound is equal to or greater than 1, the reactive compound will react sufficiently with the acidic groups in the acid-modified polyolefin resin. On the other hand, if the content of the reactive compound exceeds 10 times the amount of the reactive compound, the crosslinking reaction with the acid-modified polyolefin resin will be fully saturated, resulting in the presence of unreacted material and a risk of deterioration in various performances. Therefore, for example, the content of the reactive compound is preferably 5 to 20 parts by mass (solid content ratio) per 100 parts by mass of the acid-modified polyolefin resin.

[0061] The acid-modified polyolefin resin is a polyolefin resin into which an acidic group has been introduced. Examples of the acidic group include a carboxyl group, a sulfonic acid group, and an acid anhydride group, with a maleic anhydride group and a (meth)acrylic acid group being particularly preferred. For example, the acid-modified polyolefin resin may be the same as the modified polyolefin resin used in the sealant layer 16.

[0062] The second adhesive layer 12b may contain various additives such as a flame retardant, a slip agent, an antiblocking agent, an antioxidant, a light stabilizer, and a tackifier.

[0063] The second adhesive layer 12b 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, from the viewpoint of suppressing a decrease in laminate strength when corrosive gases such as hydrogen sulfide or an electrolyte are involved and further suppressing a decrease in insulating properties. Examples of the carbodiimide compound include N,N'-di-o-toluylcarbodiimide, 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'-di-cyclohexylcarbodiimide, and N,N'-di-p-toluylcarbodiimide.

[0064] The adhesive for forming the second adhesive layer 12b may be, for example, a polyurethane adhesive containing a blend of a polyester polyol made of a hydrogenated dimer fatty acid and a diol and a polyisocyanate. Examples of adhesives include polyurethane resins in which a bifunctional or higher isocyanate compound is reacted with a base material such as polyester polyol, polyether polyol, acrylic polyol, or carbonate polyol, and epoxy resins in which an amine compound or the like is reacted with a base material having an epoxy group, and these are preferred from the viewpoint of heat resistance.

[0065] The thickness of the second adhesive layer 12b is not particularly limited, but is preferably 1 to 10 μm, more preferably 2 to 7 μm, from the viewpoint of obtaining the desired adhesive strength and processability.

[0066] <Sealant layer 16> The sealant layer 16 is a layer that imparts heat-sealing sealing properties to the exterior material 10, and is a layer that is disposed on the inside and heat-sealed (thermally fused) when assembling the all-solid-state battery.

[0067] The moisture content of the sealant layer 16 is 2700 ppm by mass or less. In this case, the generation of bubbles in the sealant layer during heat sealing can be more effectively suppressed than when the moisture content of the sealant layer 16 exceeds 2700 ppm by mass.

[0068] The moisture content of the sealant layer 16 is preferably 2000 ppm by mass or less, and more preferably 1500 ppm by mass or less. The moisture content of the sealant layer 16 may be 0 ppm by mass.

[0069] It is sufficient that the overall moisture content of the sealant layer 16 is 2700 ppm by mass or less. Therefore, when the sealant layer 16 is composed of a multilayer film, the moisture content of each layer may be 2700 ppm by mass or less, but it is also sufficient that the moisture content of some layers is 2700 ppm by mass or less and the moisture content of the remaining layers is greater than 2700 ppm by mass, as long as the overall moisture content is 2700 ppm by mass or less.

[0070] The sealant layer 16 can be made of a film containing a thermoplastic resin, such as a polyolefin resin, a polyester resin, a polycarbonate resin, a polyphenylene ether resin, a polyacetal resin, a polystyrene resin, a polyvinyl chloride resin, or a polyvinyl acetate resin. By blending the various resins listed above to form a polymer alloy, sealing properties and heat resistance can be controlled. Among these, a film containing a polyolefin resin (hereinafter also referred to as a "polyolefin film") or a film containing a polyester resin (hereinafter also referred to as a "polyester film") is preferably used. This improves sealing properties relative to the exterior packaging material 10. Furthermore, since polyolefin films and polyester films have heat resistance, the exterior packaging material 10 can further improve the heat resistance of the all-solid-state battery. It is preferable that the thermoplastic resin does not contain a hydrophilic group component or contains a small proportion of a hydrophilic group component. In this case, the thermoplastic resin is less likely to adsorb moisture, making it easier to maintain the moisture content of the sealant layer 16 at 2700 ppm by mass or less.

[0071] Examples of polyolefin resins include low-, medium-, or high-density polyethylene; ethylene-α-olefin copolymer; polypropylene; block or random copolymers containing propylene as a copolymerization component; and propylene-α-olefin copolymers. The polyolefin resin may be an acid-modified polyolefin resin obtained by modifying a polyolefin resin with acid or glycidyl. When a polyolefin film is directly laminated to the barrier layer 13 without the corrosion prevention treatment layer 14b and the second adhesive layer 12b, it is preferable that the polyolefin film contains an acid-modified polyolefin resin layer containing an acid-modified polyolefin resin, and that this acid-modified polyolefin resin layer is directly laminated to the barrier layer 13. In this case, moisture is less likely to be absorbed into the sealant layer 16 than when the acid-modified polyolefin resin layer of the polyolefin film is directly laminated to the barrier layer 13 and the acid-modified polyolefin resin layer of the polyolefin film and the barrier layer 13 are bonded together with a polyurethane-based adhesive, which is used as a high-temperature-resistant adhesive. Therefore, even if the packaging material 10 is repeatedly exposed to high temperatures, it is unlikely that moisture will be released each time from the sealant layer 16. Therefore, when an all-solid-state battery contains a sulfide-based solid electrolyte as a solid electrolyte in an outer packaging bag, it is possible to suppress the generation of hydrogen sulfide due to a reaction between the released moisture and sulfide.

[0072] Examples of polyester resins include polyethylene terephthalate (PET) resin, polybutylene terephthalate (PBT) resin, polyethylene naphthalate (PEN) resin, polybutylene naphthalate (PBN) resin, and copolymers thereof. These polyester resins may be used alone or in combination of two or more. Also, copolymers of any acid and glycol may be used.

[0073] The sealant layer 16 may further contain additives such as antioxidants, slip agents, flame retardants, antiblocking agents, light stabilizers, dehydrating agents, tackifiers, crystal nucleating agents, and plasticizers to impart sealing properties, heat resistance, and other functionalities.

[0074] The melting point of the sealant layer 16 is not particularly limited, but is preferably 150°C or higher, more preferably 155°C or higher, and even more preferably 160°C or higher. When the melting point of the sealant layer 16 is 150°C or higher, it is possible to prevent a decrease in the seal strength of the packaging material 10 even when the packaging material 10 is used in a high-temperature environment. Therefore, when an all-solid-state battery contains a sulfide-based solid electrolyte as the solid electrolyte in an outer packaging bag, even if gases such as hydrogen sulfide are generated by a reaction between moisture and the sulfide-based solid electrolyte in the outer packaging bag of the all-solid-state battery, leakage of such gases can be further prevented.

[0075] The melting point of the sealant layer 16 is preferably 250°C or lower, more preferably 240°C or lower, and even more preferably 230°C or lower. In this case, the melting point of the sealant layer 16 being 250°C or lower allows the heat sealing temperature to be lowered. This further reduces the generation of bubbles in the sealant layer 16 during heat sealing. This further prevents the deterioration of the seal strength and barrier properties of the packaging material 10. This allows the packaging material 10 to more fully maintain the hermeticity of the packaging bag for the all-solid-state battery. The packaging material 10 can also prevent moisture from penetrating through the packaging material 10.

[0076] The sealant layer 16 may be either a single-layer film or a multilayer film, and may be selected depending on the required function. When the sealant layer 16 is a multilayer film, the layers may be laminated by coextrusion or dry lamination. However, when the sealant layer 16 is a multilayer film, it is preferable to use the same type of resin from the viewpoint of interlayer adhesion. For example, a layer containing a modified polyolefin resin may be disposed in contact with the barrier layer 13, and one layer of unmodified polyolefin resin may be extruded or multiple layers of polyolefin resin may be coextruded on top of that layer.

[0077] The thickness of the sealant layer 16 is not particularly limited, but is preferably 10 to 100 μm, and more preferably 20 to 60 μm. When the thickness of the sealant layer 16 is 10 μm or more, sufficient sealing strength can be obtained. When the thickness of the sealant layer 16 is 100 μm or less, the amount of water vapor penetrating from the peripheral edge of the packaging material 10 can be reduced.

[0078] <Hydrogen sulfide decomposition and adsorption material> When the exterior packaging material 10 is used in an all-solid-state battery having a sulfide-based solid electrolyte, at least one of the layers constituting the exterior packaging material 10 of this embodiment may contain a hydrogen sulfide decomposition / adsorption material that decomposes or adsorbs hydrogen sulfide. In this case, even if hydrogen sulfide is generated by reaction between water and the sulfide-based solid electrolyte in the all-solid-state battery, the hydrogen sulfide is prevented from permeating through the exterior packaging material 10. The hydrogen sulfide decomposition / adsorption material is contained in, for example, the first adhesive layer 12a, the second adhesive layer 12b, the sealant layer 16, or at least one of these. In particular, the hydrogen sulfide decomposition / adsorption material is preferably contained in the sealant layer 16. In this case, the hydrogen sulfide is effectively prevented from permeating through the exterior packaging material 10.

[0079] Examples of hydrogen sulfide decomposition and adsorption materials include zinc oxide, amorphous metal silicates (mainly those containing copper or zinc), zirconium and tantanide hydrates, tetravalent metal phosphates (especially those containing copper), mixtures of zeolite and zinc ions, mixtures of zeolite, zinc oxide, and copper(II) oxide, potassium permanganate, sodium permanganate, silver sulfate, silver acetate, aluminum oxide, iron hydroxide, isocyanate compounds, aluminum silicate, potassium aluminum sulfate, zeolite, activated carbon, amine compounds, and ionomers. Furthermore, hydrogen sulfide decomposition and adsorption materials preferably contain zinc oxide (ZnO) and / or zinc ions, which facilitates detoxifying hydrogen sulfide and is advantageous in terms of cost and ease of handling. These hydrogen sulfide decomposition and adsorption materials can be used singly or in combination.

[0080] The hydrogen sulfide decomposition / adsorption material may be a deodorizer that has a deodorizing effect on hydrogen sulfide, such as "Daimshoo PE-M 3000-Z" (a polyethylene masterbatch product) manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd., "Kesmon" manufactured by Toagosei Co., Ltd., "Shoe Cleanse" manufactured by Rasa Kogyo Co., Ltd., and "Dashlight ZU" and "Dashlight CZU" manufactured by Sinanen Zeomic Corporation.

[0081] A metal soap such as zinc stearate may be added to the layer containing the hydrogen sulfide decomposition / adsorption material to improve the dispersibility of the hydrogen sulfide decomposition / adsorption material. By using the hydrogen sulfide decomposition / adsorption material in combination with a metal soap, the dispersibility of the hydrogen sulfide decomposition / adsorption material in the layer can be improved, making it less likely that the effect of detoxifying hydrogen sulfide will be uneven, and making it easier to prevent a decrease in the functionality (e.g., adhesion strength, seal strength, etc.) of the layer containing the hydrogen sulfide decomposition / adsorption material.

[0082] The hydrogen sulfide decomposition and adsorption material may be used in the form of a masterbatch in advance. When the hydrogen sulfide decomposition and adsorption material is to be blended into the sealant layer 16, a high concentration blend may be prepared in advance as a master batch, and then the master batch may be blended into the resin of the sealant layer 16 to achieve an appropriate concentration. When the hydrogen sulfide decomposition and adsorption material is blended into the first adhesive layer 12a or the second adhesive layer 12b, it may be blended directly into the coating if the first adhesive layer 12a or the second adhesive layer 12b is coated, or when the first adhesive layer 12a or the second adhesive layer 12b is formed by extrusion or the like, it may be blended by preparing a masterbatch in the same manner as the sealant layer 16. When preparing a masterbatch, the resin that can be used may be a thermoplastic resin such as a polyolefin resin, a polyamide resin, a polyester resin, a polycarbonate resin, a polyphenylene ether resin, a polyacetal resin, a polystyrene resin, a polyvinyl chloride resin, or a polyvinyl acetate resin.

[0083] The content of the hydrogen sulfide decomposition adsorption material in the layer containing the hydrogen sulfide decomposition adsorption material may be 0.01% by mass to 30% by mass, 0.05% by mass to 20% by mass, or 0.1% by mass to 15% by mass, based on the total mass of the layer. When the content of the hydrogen sulfide decomposition adsorption material is equal to or greater than the lower limit, the effect of detoxifying hydrogen sulfide is easily achieved, and when the content is equal to or less than the upper limit, deterioration of the functionality (e.g., adhesion strength, seal strength, etc.) of the layer containing the hydrogen sulfide decomposition adsorption material can be suppressed.

[0084] Although the preferred embodiment of the all-solid-state battery exterior material of this embodiment has been described in detail above, the present disclosure is not limited to such a specific embodiment.

[0085] For example, Figure 1 shows a case where corrosion prevention treatment layers 14a and 14b are provided on both sides of the barrier layer 13, but only one of the corrosion prevention treatment layers 14a and 14b may be provided, or no corrosion prevention treatment layer may be provided.

[0086] 1 shows a case where the barrier layer 13 and the sealant layer 16 are laminated using the second adhesive layer 12b, but the barrier layer 13 and the sealant layer 16 may be laminated using an adhesive resin layer 15 as in the all-solid-state battery packaging material 20 shown in Fig. 2. Furthermore, in the all-solid-state battery packaging material 20 shown in Fig. 2, the second adhesive layer 12b may be provided between the barrier layer 13 and the adhesive resin layer 15.

[0087] <Adhesive resin layer 15> The adhesive resin layer 15 is generally composed of an adhesive resin composition as a main component and additive components as necessary. The adhesive resin composition is not particularly limited, but preferably contains a modified polyolefin resin.

[0088] The modified polyolefin resin is preferably a polyolefin resin graft-modified with an unsaturated carboxylic acid derivative derived from an unsaturated carboxylic acid, or an acid anhydride or ester thereof.

[0089] Examples of polyolefin resins include low-density polyethylene, medium-density polyethylene, high-density polyethylene, ethylene-α-olefin copolymer, homopolypropylene, block polypropylene, random polypropylene, and propylene-α-olefin copolymer.

[0090] The modified polyolefin resin is preferably a polyolefin resin modified with maleic anhydride. Suitable modified polyolefin resins include, for example, "Admer" manufactured by Mitsui Chemicals, Inc. and "Modic" manufactured by Mitsubishi Chemical Corporation. Such modified polyolefin resins have excellent reactivity with various metals and polymers having various functional groups, and this reactivity can be utilized to impart adhesion to the adhesive resin layer 15. Furthermore, the adhesive resin layer 15 may contain various additives, such as compatible and incompatible elastomers, flame retardants, slip agents, antiblocking agents, antioxidants, light stabilizers, and tackifiers, as needed.

[0091] The thickness of the adhesive resin layer 15 is not particularly limited, but is preferably the same as or smaller than that of the sealant layer 16 from the viewpoint of stress relaxation and moisture permeation.

[0092] In addition, in the all-solid-state battery packaging material 20, the total thickness of the adhesive resin layer 15 and the sealant layer 16 is preferably in the range of 5 to 100 μm, more preferably in the range of 20 to 80 μm, from the viewpoint of achieving both a thin film and improved heat seal strength in a high-temperature environment.

[0093] In the packaging material 20, the hydrogen sulfide decomposition / adsorbing material may be contained in the adhesive resin layer 15. In the packaging material 20, the hydrogen sulfide decomposition / adsorbing material may be contained in at least one layer selected from the group consisting of the first adhesive layer 12a, the adhesive resin layer 15, and the sealant layer 16.

[0094] The packaging material of the present disclosure may further include a protective layer 17 arranged on the surface of the base material layer 11 opposite to the barrier layer 13, as in the packaging material 30 for an all-solid-state battery shown in Fig. 3. In Fig. 3, the adhesive resin layer 15 may be a second adhesive layer 12b.

[0095] <Protective layer 17> The protective layer 17 is a layer that protects the base material layer 11. The same material as that of the first adhesive layer 12a can be used as a material constituting the protective layer 17. The protective layer 17 can be formed on the base material layer 11 by coating or the like.

[0096] In the packaging material 30, the hydrogen sulfide decomposition / adsorbing material may be contained in the protective layer 17. In the packaging material 30, the hydrogen sulfide decomposition / adsorbing material may be contained in at least one layer selected from the group consisting of the protective layer 17, the first adhesive layer 12a, the adhesive resin layer 15, and the sealant layer 16.

[0097] [Exterior material manufacturing method] Next, a description will be given of an example of a method for manufacturing the packaging material 10 shown in Fig. 1. Note that the method for manufacturing the packaging material 10 is not limited to the following method.

[0098] The manufacturing method of the exterior material 10 of this embodiment is roughly composed of the steps of providing corrosion prevention treatment layers 14a, 14b on the barrier layer 13, bonding the base material layer 11 and the barrier layer 13 together using the first adhesive layer 12a, further laminating the sealant layer 16 via the second adhesive layer 12b to produce a laminate, and, if necessary, aging the obtained laminate.

[0099] (Laminating process of corrosion prevention treatment layer onto barrier layer) This step is a step of forming corrosion prevention treatment layers 14a and 14b on the barrier layer 13. As described above, examples of the method for forming the corrosion prevention treatment layers 14a and 14b include degreasing treatment, hydrothermal treatment, anodizing treatment, and chemical conversion treatment on the barrier layer 13, and applying a coating agent having corrosion prevention properties.

[0100] Furthermore, when the corrosion prevention treatment layers 14a, 14b are multi-layered, for example, the coating liquid (coating agent) constituting the lower corrosion prevention treatment layer (barrier layer 13 side) may be applied to the barrier layer 13 and baked to form a first layer, and then the coating liquid (coating agent) constituting the upper corrosion prevention treatment layer may be applied to the first layer and baked to form a second layer.

[0101] Degreasing treatment can be performed by spraying or immersion. Hydrothermal conversion treatment and anodizing treatment can be performed by immersion. Chemical conversion treatment can be performed by immersion, spraying, coating, or other methods appropriately selected depending on the type of chemical conversion treatment.

[0102] As a method for applying a coating agent having corrosion prevention properties, various methods such as gravure coating, reverse coating, roll coating, and bar coating can be used.

[0103] As described above, the various treatments may be applied to either one or both sides of the metal foil, but in the case of one-side treatment, the treated side is preferably the side on which the sealant layer 16 is laminated. If desired, the above treatments may also be applied to the surface of the base layer 11.

[0104] The amount of coating agent applied to form the first layer and the second layer is 0.005 to 0.200 g / m 2 is preferable, and 0.010 to 0.100 g / m 2 is more preferred.

[0105] Furthermore, if dry curing is required, it can be carried out at a base material temperature in the range of 60 to 300° C. depending on the drying conditions of the corrosion prevention treatment layers 14a and 14b used.

[0106] (Step of bonding the substrate layer and the barrier layer) This step is a step of bonding the barrier layer 13 provided with the corrosion prevention treatment layers 14a and 14b to the base material layer 11 via the first adhesive layer 12a. The bonding method may be dry lamination, non-solvent lamination, wet lamination, or the like, and the two are bonded together using the material that constitutes the first adhesive layer 12a described above. The first adhesive layer 12a has a dry coating amount of 1 to 10 g / m. 2 range, more preferably 2 to 7 g / m 2 It is set within the range.

[0107] (Laminating step of second adhesive layer and sealant layer) This step is a step of bonding the sealant layer 16 via the second adhesive layer 12b to the second corrosion prevention treatment layer 14b side of the barrier layer 13. Examples of bonding methods include a wet process and dry lamination.

[0108] In the case of a wet process, a solution or dispersion of the adhesive constituting the second adhesive layer 12b is applied onto the second corrosion prevention treatment layer 14b, the solvent is evaporated at a predetermined temperature to form a dry film, and a baking process is further performed as necessary. Thereafter, the sealant layer 16 is laminated to produce the exterior material 10. Examples of application methods include the various application methods exemplified above. The preferred dry application amount of the second adhesive layer 12b is the same as that of the first adhesive layer 12a.

[0109] In this case, the sealant layer 16 can be produced, for example, by a melt extrusion molding machine using a resin composition for forming a sealant layer containing the above-mentioned components of the sealant layer 16. From the viewpoint of productivity, the processing speed of the melt extrusion molding machine can be set to 80 m / min or more.

[0110] (Aging treatment process) This step is a step of aging (curing) the laminate. By aging the laminate, it is possible to promote adhesion between the barrier layer 13, the second corrosion prevention treatment layer 14b, the second adhesive layer 12b, and the sealant layer 16. The aging treatment can be carried out at a temperature ranging from room temperature to 100°C. The aging time is, for example, 1 to 10 days.

[0111] In this manner, the packaging material 10 of this embodiment as shown in FIG. 1 can be manufactured.

[0112] Next, a description will be given of an example of a method for manufacturing the exterior packaging material 20 shown in Fig. 2. Note that the method for manufacturing the exterior packaging material 20 is not limited to the following method.

[0113] The manufacturing method of the packaging material 20 of this embodiment is generally composed of the steps of providing corrosion prevention treatment layers 14a, 14b on the barrier layer 13, bonding the base material layer 11 and the barrier layer 13 together using the first adhesive layer 12a, further laminating the adhesive resin layer 15 and the sealant layer 16 to prepare a laminate, and, if necessary, heat treating the obtained laminate. Note that the steps up to the step of bonding the base material layer 11 and the barrier layer 13 can be carried out in the same manner as the manufacturing method of the packaging material 10 described above.

[0114] (Laminating process of adhesive resin layer and sealant layer) This step is a step of forming an adhesive resin layer 15 and a sealant layer 16 on the second corrosion prevention treatment layer 14b formed in the previous step. Examples of methods include sand lamination of the adhesive resin layer 15 together with the sealant layer 16 using an extrusion laminator. Furthermore, lamination can also be performed using a tandem lamination method or a co-extrusion method in which the adhesive resin layer 15 and the sealant layer 16 are extruded. When forming the adhesive resin layer 15 and the sealant layer 16, for example, the components are blended so as to satisfy the above-described structures of the adhesive resin layer 15 and the sealant layer 16. The above-described resin composition for forming a sealant layer is used to form the sealant layer 16.

[0115] This process produces a laminate in which the layers are stacked in the following order: base layer 11 / first adhesive layer 12a / first corrosion prevention treatment layer 14a / barrier layer 13 / second corrosion prevention treatment layer 14b / adhesive resin layer 15 / sealant layer 16, as shown in Figure 2.

[0116] The adhesive resin layer 15 may be formed by directly extruding dry-blended materials having the above-described material composition using an extrusion laminator. Alternatively, the adhesive resin layer 15 may be formed by extruding granules obtained by previously melt-blending the materials using a melt-kneading device such as a single-screw extruder, a twin-screw extruder, or a Brabender mixer, and then extruding the granules using an extrusion laminator.

[0117] The sealant layer 16 may be formed by directly extruding materials dry-blended to the composition described above as the constituent components of the resin composition for forming a sealant layer using an extrusion laminator. Alternatively, the adhesive resin layer 15 and the sealant layer 16 may be formed by a tandem lamination method in which the granules obtained by melt-blending the resin composition using a melt-kneading device such as a single-screw extruder, a twin-screw extruder, or a Brabender mixer are extruded into the adhesive resin layer 15 and the sealant layer 16 using an extrusion laminator, or by a co-extrusion method. Alternatively, a sealant monolayer may be formed in advance as a cast film using the resin composition for forming a sealant layer, and this film may be laminated together with an adhesive resin by sand lamination. The formation speed (processing speed) of the adhesive resin layer 15 and the sealant layer 16 may be, for example, 80 m / min or more from the viewpoint of productivity.

[0118] (Heat treatment process) This step is a step of heat-treating the laminate. Heat-treating the laminate can improve adhesion between the barrier layer 13, the second corrosion prevention treatment layer 14b, the adhesive resin layer 15, and the sealant layer 16. As a method of heat treatment, it is preferable to treat at a temperature at least equal to or higher than the melting point of the adhesive resin layer 15.

[0119] In this manner, the exterior packaging material 20 of this embodiment as shown in FIG. 2 can be manufactured.

[0120] [All-solid battery] FIG. 4 is a perspective view showing one embodiment of an all-solid-state battery produced using the above-described exterior material 10. As shown in FIG. 4, the all-solid-state battery 50 includes a battery body 52 having a sulfide-based electrolyte as a solid electrolyte, two metal terminals (current extraction terminals) 53 for extracting current from the battery body 52 to the outside, and an exterior bag 54 that hermetically encases the battery body 52. ​​The exterior bag 54 is obtained by heat-sealing the exterior material 10 according to the above-described embodiment, and is used as a container for accommodating the battery body 52. ​​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 configured to encase the battery body 52 by folding one laminate film in half and heat-sealing the peripheral portions thereof, or by overlapping two laminate films and heat-sealing the peripheral portions thereof, so that the base material layer 11 is on the outer side of the all-solid-state battery 50 and the sealant layer 16 is on the inner side of the all-solid-state battery 50. The metal terminal 53 is sandwiched by an exterior bag 54 with the sealant layer 16 on the inside. The metal terminal 53 may be sandwiched by the exterior bag 54 via a tab sealant.

[0121] Battery body 52 has at least one power generating element consisting of a positive electrode, a solid electrolyte, and a negative electrode. Metal terminal 53 is a part of the current collector that is taken out of exterior packaging 10, and is made of metal foil such as copper foil or aluminum foil.

[0122] In the all-solid-state battery 50, the outer bag 54 is obtained by heat-sealing the exterior material 10. Here, the exterior material 10 can suppress the generation of air bubbles in the sealant layer 16 during heat sealing. Therefore, in the all-solid-state battery 50, the sealant layer 16 of the exterior material 10 is prevented from having rough and dense portions, which would otherwise cause a decrease in seal strength at the rough portions. Therefore, even if the battery body 52 expands during use of the all-solid-state battery 50 in a high-temperature environment and a force acts on the exterior bag 54 attempting to open it, the exterior material 10 can maintain the sealed state of the exterior bag 54 in the all-solid-state battery 50. As a result, even if hydrogen sulfide is generated within the exterior bag 54, leakage of the hydrogen sulfide from the exterior bag 54 is suppressed. Furthermore, the generation of air bubbles, which can easily serve as a passage for moisture, is suppressed in the sealant layer 16, thereby suppressing the intrusion of moisture from outside the exterior material 10. As a result, the generation of hydrogen sulfide due to a reaction between moisture and the sulfide-based electrolyte can be suppressed.

[0123] In the all-solid-state battery 50, the exterior bag 54 may be obtained by heat-sealing the exterior material 20 or the exterior material 30 instead of the exterior material 10. In addition, the solid electrolyte is not limited to a sulfide-based solid electrolyte, and may be an oxide-based solid electrolyte or the like. [Example]

[0124] Hereinafter, the present disclosure will be described more specifically based on examples, but the present disclosure is not limited to the following examples.

[0125] <Materials used> The materials used in the examples and comparative examples are shown below.

[0126] (base material layer) The following films were used as the substrate layers. Semi-aromatic polyamide (nylon 9T) film (manufactured by Unitika Ltd., melting point: 305°C)

[0127] (First adhesive layer) For the first adhesive layer, a polyurethane adhesive (manufactured by Toyo Ink Co., Ltd.) was used, in which a polyester polyol-based base agent was mixed with a tolylene diisocyanate adduct-based curing agent.

[0128] (First corrosion prevention treatment layer and second corrosion prevention treatment layer) The first corrosion prevention treatment layer (on the substrate layer side) and the second corrosion prevention treatment layer (on the sealant layer side) were formed using the following (CL-1) and (CL-2). (CL-1): Sodium polyphosphate-stabilized cerium oxide sol prepared using distilled water as a solvent to a solids concentration of 10% by mass. The sodium polyphosphate-stabilized cerium oxide sol was prepared by blending 100 parts by mass of cerium oxide with 10 parts by mass of sodium phosphate. (CL-2): A composition prepared by using distilled water as a solvent and adjusting the solid content concentration to 5% by mass. The composition contained "polyallylamine (manufactured by Nitto Boseki Co., Ltd.)" and "polyglycerol polyglycidyl ether (manufactured by Nagase ChemteX Corporation)" in a mass ratio of 90:10.

[0129] (barrier layer) As the barrier layer, a soft aluminum foil (manufactured by Toyo Aluminum Co., Ltd., product name: 8079 material, thickness: 40 μm) that had been annealed and degreased was used.

[0130] (Second adhesive layer) The first adhesive layer was made of the same polyurethane adhesive (manufactured by Toyo Ink Mfg. Co., Ltd., product name: TM-K55) as the first adhesive layer.

[0131] (sealant layer) The following films were used as the sealant layers. Polyolefin film 1 (PO film 1, polypropylene-polyethylene random copolymer, manufactured by Futamura Chemical Co., Ltd., product name: FHK2, thickness: 40 μm, melting point: 135°C, moisture content: 516 mass ppm) Polyolefin film 2 (PO film 2, acid-modified polypropylene (thickness: 12.5 μm, melting point: 160°C) and polypropylene (thickness: 12.5 μm, melting point: 160°C) laminate (melting point: 160°C, thickness: 25 μm, moisture content: 546 mass ppm) Polyester film 1 (polyethylene terephthalate, manufactured by Unitika Ltd., product name: Emblet, thickness: 25 μm, melting point: 257°C, moisture content: 2682 mass ppm) Polyester film 2 (polyethylene naphthalate, manufactured by Toyobo Co., Ltd., product name: Teonex, thickness: 25 μm, melting point: 265°C, moisture content: 2637 ppm by mass) Polyester film 3 (copolymer of multiple types of polyethylene terephthalate, manufactured by Unitika Ltd., thickness: 25 μm, melting point: 210°C, moisture content: 1648 mass ppm) Polyamide film (PA film, nylon 6, manufactured by Toyobo Co., Ltd., product name: Harden N1102, thickness: 25 μm, melting point: 225°C, moisture content: 23729 ppm by mass) The moisture content was measured as follows. That is, a film cut into 10 cm squares was left in an environment of 23°C / 50%RH for two days, and then heated using a thermal moisture vaporizer (manufactured by Hiranuma Corporation, product name: EV-2000) set at 300°C, and the amount of moisture generated was measured using a trace moisture analyzer (Karl Fischer: Hiranuma Corporation "AQ-2100"). At this time, dry N2 gas was used as the carrier gas. Then, using the moisture amount measured as above, the moisture content was calculated according to the following formula. Moisture content (mass ppm) = measured moisture amount (g) / film mass (g)

[0132] Examples 1 to 4 First, a first corrosion prevention treatment layer and a second corrosion prevention treatment layer were provided on the barrier layer by the following procedure: First, (CL-1) was applied to both surfaces of the barrier layer in a dry coating amount of 70 mg / m 2The resulting layer was coated by microgravure coating so that the coating amount was 20 mg / m, and then baked in a drying unit at 200°C. 2 The coating was applied by microgravure coating so that the thickness of the coating was 1 / 2. In this way, composite layers made of (CL-1) and (CL-2) were formed on both sides of the barrier layer as first and second corrosion prevention treatment layers, respectively, to obtain a first laminate. These composite layers exhibit corrosion prevention performance by combining the two types of (CL-1) and (CL-2).

[0133] Next, the first corrosion prevention treatment layer side of the barrier layer (first laminate) provided with the first and second corrosion prevention treatment layers was attached to the substrate layer using a polyurethane adhesive (first adhesive layer) by dry lamination to obtain a laminate (second laminate) of the first laminate and the substrate layer. Specifically, the polyurethane adhesive was applied to the surface of the barrier layer facing the first corrosion prevention treatment layer so that the thickness after curing would be 5 μm, and after drying at 80°C for 1 minute, it was laminated to the substrate layer and aged at 60°C for 120 hours to obtain the second laminate.

[0134] Next, the laminate (second laminate) including the barrier layer and the base layer was set on the unwinding section of an extrusion laminator, and a sealant layer of the type shown in Table 1 was attached to the second corrosion prevention treatment layer by dry lamination using a polyurethane adhesive (second adhesive layer), to obtain a structure. Specifically, the polyurethane adhesive was applied to the surface of the barrier layer facing the second corrosion prevention treatment layer so that the thickness after curing would be 5 μm, and after drying at 80°C for 1 minute, it was laminated with the sealant layer of the type shown in Table 1 and aged at 60°C for 120 hours to obtain a structure.

[0135] In this way, an exterior material (a laminate of substrate layer / first adhesive layer / first corrosion prevention treatment layer / barrier layer / second corrosion prevention treatment layer / second adhesive layer / sealant layer) was obtained.

[0136] Example 5 An exterior material (a laminate of substrate layer / first adhesive layer / first corrosion prevention treatment layer / barrier layer / second corrosion prevention treatment layer / sealant layer) was produced in the same manner as in Example 1, except that a laminate of the barrier layer and substrate layer was set on the unwinding section of an extrusion laminator, and a sealant layer of the type shown in Table 1 was attached to the second corrosion prevention treatment layer by thermal lamination to obtain a structure. At this time, the thermal lamination of the second laminate including the barrier layer and substrate layer with the sealant layer was carried out by heating at a temperature of 190°C under a pressure of 0.5 MPa.

[0137] (Comparative Example 1) An exterior material (a laminate of substrate layer / first adhesive layer / first corrosion prevention treatment layer / barrier layer / second corrosion prevention treatment layer / second adhesive layer / sealant layer) was produced in the same manner as in Example 1, except that the types of sealant layers shown in Table 1 were used as the sealant layers.

[0138] <Exterior material evaluation> The exterior packaging material was cut into a size of 120 mm x 60 mm and folded in half with the sealant layer facing inward. The two longitudinal ends of the exterior packaging material were then overlapped. These ends were heat-sealed for 3 seconds at a temperature 20°C above the melting point of the sealant layer while applying a pressure of 0.5 MPa, forming a 10 mm-wide heat-sealed section (the shaded area in Figure 5 ), thereby producing a structure. The structure was then stored at room temperature for 12 hours. A 15 mm x 30 mm-wide piece was then cut from the structure at the center of the longitudinal direction of the heat-sealed section (see Figure 5 ) to produce an evaluation sample. This evaluation sample was then separated into two pieces at the heat-sealed section. The sealant layer of each separated piece was visually observed, and the state of bubble formation in the sealant layer was evaluated based on the following criteria. The results are shown in Table 1. When the sealant layer was a multilayer film, the "melting point of the sealant layer" was defined as the melting point of the layer with the lowest melting point among the layers constituting the multilayer film. (Evaluation criteria) ◎: No bubbles are observed ○: Localized bubbles are observed ×: Bubbles are observed all over the surface

[0139] [Table 1]

[0140] The results shown in Table 1 show that the packaging materials of Examples 1 to 6, which have a moisture content of 2700 mass ppm or less, suppress the generation of bubbles compared to the packaging material of Comparative Example 1, which has a moisture content of more than 2700 mass ppm.

[0141] Therefore, it was confirmed that the packaging material for an all-solid-state battery according to the present disclosure can suppress the generation of bubbles during heat sealing. [Explanation of symbols]

[0142] Reference Signs List 10, 20, 30... all-solid-state battery casing material, 11... substrate layer, 12a... first adhesive layer, 12b... second adhesive layer, 13... barrier layer, 14a... first corrosion prevention treatment layer, 14b... second corrosion prevention treatment layer, 15... adhesive resin layer, 16... sealant layer, 17... protective layer, 50... all-solid-state battery, 52... battery body, 53... metal terminal, 54... outer bag.

Claims

1. An outer casing material for an all-solid-state battery, comprising at least a substrate layer, a barrier layer, and a sealant layer in this order, The sealant layer has a moisture content of 2700 ppm by mass or less.

2. 2. The exterior packaging material for an all-solid-state battery according to claim 1, wherein the sealant layer is a polyolefin film containing a polyolefin-based resin or a polyester film containing a polyester-based resin.

3. the sealant layer is the polyolefin film, the polyolefin film includes an acid-modified polyolefin resin layer, The all-solid-state battery exterior packaging material according to claim 2 , wherein the acid-modified polyolefin resin layer is directly laminated to the barrier layer.

4. The all-solid-state battery exterior material according to any one of claims 1 to 3, wherein the melting point of the sealant layer is 250°C or lower.

5. The all-solid-state battery exterior material according to any one of claims 1 to 4, wherein the sealant layer has a melting point of 150°C or higher.

6. a battery body including a solid electrolyte; an outer bag that houses the battery body, The all-solid-state battery, wherein the outer packaging bag is obtained by heat-sealing the outer packaging material for an all-solid-state battery according to any one of claims 1 to 5.

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