Sheath material for power storage device

Abstract

To provide a sheath material for a power storage device which can secure excellent heat seal strength under high temperature environment, and can secure excellent heat seal strength under room temperature environment after having been exposed to high temperature environment.SOLUTION: A sheath material for a power storage device includes at least a base material, a barrier layer, and a sealant layer in this order, wherein the sealant layer contains polyolefin as a first resin, and at least one kind of a resin selected from the group consisting of polyester, polyamide, polycarbonate and polyphenylene ether as a second resin.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an exterior material for a power storage device and a power storage device using the same. [Background technology]

[0002] Known examples of power storage devices include secondary batteries such as lithium-ion batteries, nickel-metal hydride batteries, and lead-acid batteries, as well as electrochemical capacitors such as electric double-layer capacitors. Due to the miniaturization of portable devices and limitations on installation space, there is a demand for further miniaturization of power storage devices, and lithium-ion batteries with high energy density have attracted attention. While metal cans have traditionally been used as the exterior materials for lithium-ion batteries, multilayer films have begun to be used, which are lightweight, have excellent heat dissipation properties, and can be produced at low cost.

[0003] Lithium-ion batteries that use the above multilayer film as an exterior material are called laminated lithium-ion batteries. The exterior material covers the battery contents (positive electrode, separator, negative electrode, electrolyte, etc.) and prevents moisture from penetrating into the battery. Laminated lithium-ion batteries are manufactured, for example, by forming a recess in part of the exterior material by cold forming, accommodating the battery contents in the recess, folding back the remaining part of the exterior material, and heat-sealing the edges (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-101765 Summary of the Invention [Problem to be solved by the invention]

[0005] Meanwhile, research and development is being conducted on power storage devices known as all-solid-state batteries as the next generation of lithium-ion batteries. All-solid-state batteries are characterized by using a solid electrolyte instead of an organic electrolyte solution as the electrolyte material. While lithium-ion batteries cannot be used at temperatures higher than the boiling point of the electrolyte solution (approximately 80°C), all-solid-state batteries can be used at temperatures exceeding 100°C, and the conductivity of lithium ions can be increased by operating them under high temperature conditions (for example, 100 to 150°C).

[0006] However, when a laminated all-solid-state battery is manufactured using the above-mentioned multilayer film as an exterior material, if the heat resistance of the exterior material is insufficient, interlayer adhesion (adhesion between layers fused by heat sealing) in a high-temperature environment after heat sealing cannot be ensured, and the heat seal strength may decrease, resulting in a risk of a decrease in the hermeticity of the package of the all-solid-state battery.

[0007] Therefore, from the viewpoint of ensuring heat seal strength in a high-temperature environment, the present inventors have investigated a method of using a highly heat-resistant resin for a sealant layer to be fused by heat sealing. However, the present inventors have found that when an all-solid-state battery is produced using an exterior material in which a highly heat-resistant resin is used for the sealant layer, and the battery is operated in a high-temperature environment and then returned to room temperature, a problem occurs in that the heat seal strength in a room-temperature environment decreases.

[0008] The present disclosure has been made in view of the above-described problems, and aims to provide an exterior packaging material for a power storage device that can ensure excellent heat seal strength in a high-temperature environment and can also ensure excellent heat seal strength in a room temperature environment after exposure to a high-temperature environment, and a power storage device using the same. [Means for solving the problem]

[0009] In order to achieve the above object, the present disclosure provides an exterior packaging material for an electricity storage device that includes at least a substrate layer, a barrier layer, and a sealant layer in this order, wherein the sealant layer contains a polyolefin as a first resin and at least one resin selected from the group consisting of polyester, polyamide, polycarbonate, and polyphenylene ether as a second resin.

[0010] The use of the second resin can improve the heat seal strength of the packaging material in a high-temperature environment. However, the present inventors discovered that when the second resin is used alone, when the packaging material is exposed to a high-temperature environment and then returned to room temperature, the heat seal strength at room temperature decreases compared to before exposure, making it difficult to ensure excellent heat seal strength. The second resin has high heat resistance, and its performance when used in a high-temperature environment has been studied. However, the change in heat seal strength at room temperature before and after exposure to a high-temperature environment has not been sufficiently investigated. All-solid-state batteries are repeatedly placed in a high-temperature environment during use and at room temperature when not in use, so it is necessary for the heat seal strength of the packaging material to not deteriorate even in such a usage environment. Therefore, the present inventors conducted extensive research and discovered that by using the first resin in combination with the second resin, the decrease in heat seal strength at room temperature after exposure to a high-temperature environment can be suppressed. That is, according to the above-mentioned packaging material for a storage battery device, by using a combination of a specific first resin and a specific second resin as materials for the sealant layer, it is possible to ensure excellent heat seal strength in a high-temperature environment, and also to ensure excellent heat seal strength in a room temperature environment after exposure to a high-temperature environment.

[0011] In the electrical storage device packaging material, the first resin may contain a modified polyolefin having a polar group capable of reacting with the second resin. The modified polyolefin may be a polyolefin modified with maleic anhydride. The compatibility between the first resin and the second resin may not be necessarily good, resulting in insufficient dispersibility, and the above-mentioned combined effect may not be fully achieved. In contrast, when the first resin contains a modified polyolefin having a polar group capable of reacting with the second resin, the compatibility between the first resin and the second resin can be improved, resulting in improved dispersibility. As a result, the synergistic effect of the combined use of the first resin and the second resin can be more fully achieved, ensuring superior heat seal strength in high-temperature environments and superior heat seal strength at room temperature after exposure to high-temperature environments. Furthermore, when the modified polyolefin is a polyolefin modified with maleic anhydride, the above-mentioned effect can be more fully achieved.

[0012] Here, the first resin may contain the above-mentioned modified polyolefin and a polyolefin (unmodified polyolefin) that does not have a polar group that can react with the second resin. Because the melting point and molecular weight of modified polyolefins tend to decrease upon modification, combining the modified polyolefin with a normal polyolefin (unmodified polyolefin) can prevent a decrease in heat seal strength in high-temperature environments. When modified polyolefins and unmodified polyolefins are used in combination, the modified polyolefin acts as a compatibilizer, improving the dispersibility of the unmodified polyolefin and the second resin.

[0013] In the packaging material for a power storage device, the sealant layer may contain the polyester and / or the polyamide, and the crystallinity of the polyester and / or the polyamide may be 10% or more and less than 70% after the sealant layer is heat-sealed under conditions of 260°C, 0.5 MPa, and 3 seconds and cooled to 25°C. When the crystallinity of the polyester and / or polyamide measured by the above method is within the above range, the heat seal strength in a high-temperature environment can be further improved, and the flexibility of the packaging material can also be further improved.

[0014] In the above-mentioned casing material for a power storage device, a corrosion prevention treatment layer may be provided on one or both surfaces of the barrier layer. Providing the corrosion prevention treatment layer can prevent corrosion of the barrier layer, and the presence of the corrosion prevention treatment layer can enhance the adhesion between the barrier layer and an adjacent layer. Furthermore, in all-solid-state batteries, sulfide-based materials are sometimes used as electrolytes. When moisture penetrates into the casing material, the sulfide-based compounds react with water to generate hydrogen sulfide (H2S). This H2S may reduce the adhesion between the barrier layer and an adjacent layer. However, when the above-mentioned casing material for a power storage device is used as a casing material for an all-solid-state battery, providing a corrosion prevention treatment layer on the surface of the barrier layer can impart H2S resistance to the barrier layer and prevent a reduction in the adhesion between the barrier layer and an adjacent layer. Therefore, the above-mentioned casing material for a power storage device can ensure excellent heat seal strength in a high-temperature environment even when exposed to hydrogen sulfide, and can also ensure excellent heat seal strength in a room temperature environment after exposure to a high-temperature environment.

[0015] In the above-described packaging material for a storage battery device, when the substrate layer side of the packaging material for a storage battery device is the outer side and the sealant layer side of the packaging material for a storage battery device is the inner side, at least one of the layers disposed on the inner side of the barrier layer may contain a hydrogen sulfide adsorbent. As described above, hydrogen sulfide (HS) may be generated in all-solid-state batteries. However, if at least one of the layers disposed on the inner side of the barrier layer contains a hydrogen sulfide adsorbent, the layer containing the hydrogen sulfide adsorbent can adsorb and neutralize HS generated inside the packaging material, thereby providing a higher level of protection from HS to the barrier layer, the current collector (particularly copper foil), and a positive electrode containing Ni. Therefore, the above-described packaging material for a storage battery device can ensure excellent heat seal strength in a high-temperature environment even when exposed to hydrogen sulfide, and can also ensure excellent heat seal strength in a room temperature environment after exposure to a high-temperature environment.

[0016] The packaging material for a power storage device may be used for an all-solid-state battery.

[0017] The present disclosure also provides an electricity storage device including: an electricity storage device main body; a current extracting terminal extending from the electricity storage device main body; and an exterior material for an electricity storage device according to the present disclosure, the exterior material sandwiching the current extracting terminal and housing the electricity storage device main body. The electricity storage device may be an all-solid-state battery. [Effects of the Invention]

[0018] According to the present disclosure, it is possible to provide an exterior packaging material for an electricity storage device that can ensure excellent heat seal strength in a high-temperature environment and can also ensure excellent heat seal strength in a room temperature environment after exposure to a high-temperature environment, and an electricity storage device using the same. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a schematic cross-sectional view of an exterior packaging material for a power storage device according to an embodiment of the present disclosure. [Figure 2] 1 is a schematic cross-sectional view of an exterior packaging material for a power storage device according to an embodiment of the present disclosure. [Figure 3]1 is a perspective view of an electricity storage device according to an embodiment of the present disclosure. [Figure 4] FIG. 2 is a schematic diagram illustrating a method for preparing a sample for measuring heat seal strength in the examples. DETAILED DESCRIPTION OF THE INVENTION

[0020] 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.

[0021] [Exterior materials for energy storage devices] Fig. 1 is a cross-sectional view schematically illustrating one embodiment of an exterior packaging material for an energy storage device according to the present disclosure. As shown in Fig. 1, an exterior packaging material (exterior packaging material for an energy storage device) 10 of this embodiment is a laminate including a substrate layer 11, a first adhesive layer 12a provided on one side of the substrate layer 11, a barrier layer 13 provided on the side of the first adhesive layer 12a opposite the substrate layer 11 and having first and second corrosion prevention treatment layers 14a, 14b on both sides, a second adhesive layer 12b provided on the side of the barrier layer 13 opposite the first adhesive layer 12a, and a sealant layer 16 provided on the side of the second adhesive layer 12b opposite the barrier layer 13. The first corrosion prevention treatment layer 14a is provided on the surface of the barrier layer 13 facing the substrate layer 11, and the second corrosion prevention treatment layer 14b is provided on the surface of the barrier layer 13 facing the sealant layer 16. In the packaging material 10, the base material 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 base material layer 11 facing the exterior side of the electricity storage device and the sealant layer 16 facing the interior side of the electricity storage device.

[0022] In the packaging material 10 of this embodiment, the sealant layer 16 contains a polyolefin as a first resin and at least one resin selected from the group consisting of polyester, polyamide, polycarbonate, and polyphenylene ether as a second resin. Each layer constituting the packaging material 10 will be described in detail below.

[0023] <Base material layer 11> The base material layer 11 provides heat resistance in the sealing process when manufacturing the electricity storage device and plays a role in suppressing the occurrence of pinholes that may occur during molding and distribution. In particular, in the case of an exterior material for a large-scale electricity storage device, the base material layer 11 can also provide scratch resistance, chemical resistance, insulation, etc.

[0024] 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.

[0025] 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.

[0026] 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 that constitute the polyamide film 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.

[0027] 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.

[0028] The thickness of the substrate layer 11 is preferably 6 to 40 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 exceeds 40 μm, the total thickness of the packaging material 10 tends to be large.

[0029] In order to suppress deformation of the base layer 11 during sealing, the peak melting temperature of the base layer 11 is higher than the peak melting temperature of the sealant layer 16, and is preferably 30°C or more higher than the peak melting temperature of the sealant layer 16.

[0030] <First adhesive layer 12a> 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.

[0031] 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.

[0032] <Barrier layer 13> The barrier layer 13 has water vapor barrier properties that prevent moisture from penetrating into the interior of the electricity storage device. The barrier layer 13 may also have extensibility to allow 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.

[0033] 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.

[0034] 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.

[0035] <First and second corrosion prevention treatment layers 14a, 14b> 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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 (1) stabilize the dispersion of the sol, (2) improve adhesion to the barrier layer 13 by utilizing the aluminum chelating ability of phosphoric acid, (3) impart corrosion resistance by capturing aluminum ions eluted by the influence of acids or corrosive gases (passivation formation), and (4) improve the cohesion of the corrosion prevention treatment layers (oxide layers) 14a, 14b by easily causing dehydration condensation of phosphoric acid even at low temperatures.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] From the viewpoint of easily maintaining the adhesion between the sealant layer and the barrier layer, 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.

[0048] <Second adhesive layer 12b> 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.

[0049] When a 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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 amount is equal to or greater than 10 times, the reactive compound will react sufficiently with the acidic groups in the acid-modified polyolefin resin. On the other hand, if the amount exceeds 10 times, the crosslinking reaction with the acid-modified polyolefin resin will be fully saturated, resulting in the presence of unreacted material, which may lead to a decrease 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] <Sealant layer 16> The sealant layer 16 is a layer that imparts heat-sealing sealing properties to the packaging material 10, and is a layer that is placed on the inside and heat-sealed (thermally fused) when assembling the electricity storage device.

[0062] The sealant layer 16 contains a polyolefin as a first resin and at least one resin selected from the group consisting of polyester, polyamide, polycarbonate, and polyphenylene ether as a second resin.

[0063] Examples of polyolefins include polyethylenes such as low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE), and high-density polyethylene (HDPE); ethylene-α-olefin copolymers; polypropylene; block or random copolymers containing propylene as a copolymerization component; propylene-α-olefin copolymers; and polybutene. Among these, polypropylene is preferred from the viewpoint of heat resistance and flexibility, and block polypropylene (block PP) is particularly preferred. The above-mentioned polyolefins may be used alone or in combination of two or more.

[0064] The polyolefin preferably includes a modified polyolefin having a polar group capable of reacting with the second resin. Here, examples of the functional group possessed by the second resin include the following functional groups: When the second resin is a polyester, examples of the functional group include a terminal hydroxyl group, a terminal carboxyl group, and an ester bond; When the second resin is a polyamide, examples of the functional group include a terminal amino group and an amide bond; When the second resin is a polycarbonate, examples of the functional group include a terminal hydroxyl group and an ester bond; When the second resin is a polyphenylene ether, examples of the functional group include a terminal hydroxyl group.

[0065] Examples of polar groups that can react with the functional groups of the second resin include, when the second resin is polyester or polycarbonate, hydroxyl groups, acid-modified (ester) groups, aldehyde groups, oxazoline groups, glycidyl groups, amide groups, and imino groups. When the second resin is polyamide, examples of polar groups include, when the second resin is polyphenylene ether, acid-modified (ester) groups, oxazoline groups, glycidyl groups, amide groups, and imino groups.

[0066] Modified polyolefins having hydroxyl groups as polar groups are commercially available, such as "Poval" manufactured by Kuraray Co., Ltd. and "Mersene H" manufactured by Tosoh Corporation. Modified polyolefins having glycidyl groups as polar groups are commercially available, such as "Modiper" manufactured by NOF Corporation and "LOTADER" and "BONDINE" manufactured by Arkema. Modified polyolefins having amide groups as polar groups are commercially available, such as "APOLHYA" manufactured by Arkema. Modified polyolefins having imino groups as polar groups are commercially available, such as "Admer IP" manufactured by Mitsui Chemicals, Inc. Modified polyolefins having oxazoline groups as polar groups are commercially available, such as "Epocross" manufactured by Nippon Shokubai Co., Ltd.

[0067] Examples of acid-modified polyolefins include acid-modified polyolefins modified with any of unsaturated carboxylic acids, acid anhydrides of unsaturated carboxylic acids, and esters of unsaturated carboxylic acids.

[0068] Specific examples of unsaturated carboxylic acids include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, tetrahydrophthalic acid, and bicyclo[2,2,1]hept-2-ene-5,6-dicarboxylic acid.

[0069] Examples of the acid anhydrides of unsaturated carboxylic acids include acid anhydrides of unsaturated carboxylic acids such as maleic anhydride, itaconic anhydride, citraconic anhydride, tetrahydrophthalic anhydride, and bicyclo[2,2,1]hept-2-ene-5,6-dicarboxylic anhydride.

[0070] Examples of the esters of unsaturated carboxylic acids 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, and dimethyl bicyclo[2,2,1]hept-2-ene-5,6-dicarboxylate.

[0071] Specific examples of acid-modified polyolefin products include the following: Polyolefins modified with maleic anhydride include "ADMER" manufactured by Mitsui Chemicals, Inc., "MODIC" manufactured by Mitsubishi Chemical Corporation, "TOYOTAC" manufactured by Toyobo Co., Ltd., and "SUNTACK" manufactured by Sanyo Chemical Industry Co., Ltd. Furthermore, examples of acid-modified polyolefins having carboxyl groups as polar groups include "NUCREL" and "HIMILAN" manufactured by DuPont-Mitsui Polychemicals (ionomer-based polyolefins can also be used). Examples of acid-modified polyolefins having ester groups as polar groups include "EVAFLEX" manufactured by DuPont-Mitsui Polychemicals, and "LOTADER," "BONDINE," and "EVATANE" manufactured by Arkema.

[0072] The acid-modified polyolefin is preferably a polyolefin modified with maleic anhydride. The above-mentioned modified polyolefins may be used singly or in combination of two or more.

[0073] The polyester, which is the second resin, can be obtained by reacting an acid component with a glycol component. Examples of the acid component include phthalic acid, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, cyclohexanedicarboxylic acid, adipic acid, and sebacic acid. Examples of the glycol component include ethylene glycol, butanediol, pentanediol, hexanediol, neopentyl glycol, diethylene glycol, polytetramethylene glycol, cyclohexanedimethanol, and propanediol. Specific examples of the polyester include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polycyclohexanedimethylene terephthalate (PCT).

[0074] Examples of polyamides that are the second resin include nylon-based polyamides such as nylon 6, nylon 11, nylon 12, and nylon 6,6, and aromatic aramid-based polyamides.

[0075] When polyester and / or polyamide is used as the second resin, the crystallinity of the polyester and / or polyamide is preferably 10% or more and less than 70% after heat-sealing the sealant layer 16 containing the polyester and / or polyamide under conditions of 260°C, 0.5 MPa, and 3 seconds and cooling to 25°C. If the crystallinity of the polyester and / or polyamide measured by the above method is too low, the heat seal strength in a high-temperature environment tends to decrease, while if it is too high, the flexibility tends to decrease. From the viewpoint of achieving both heat seal strength and flexibility in a high-temperature environment, the crystallinity is more preferably 15% or more and less than 50%. Note that since polycarbonate and polyphenylene ether are non-crystalline, there is no preferred range for the crystallinity.

[0076] The second resin may be used singly or in combination of two or more.

[0077] The content of the first resin in the sealant layer 16 is preferably 10 to 80% by mass, more preferably 20 to 70% by mass, and even more preferably 40 to 60% by mass, based on the total amount of the first resin and second resin in the sealant layer 16. A first resin content of 10% by mass or more makes it easier to ensure excellent heat seal strength at room temperature after exposure to a high-temperature environment, while a first resin content of 80% by mass or less makes it easier to ensure even excellent heat seal strength in a high-temperature environment. The first resin and second resin may be melt-kneaded in advance using a kneader or the like.

[0078] The content of the modified polyolefin in the first resin is preferably 0.1 to 100% by mass, and more preferably 0.5 to 40% by mass, based on the total amount of the first resin. When the content of the modified polyolefin is 0.1% by mass or more, the polar groups of the modified polyolefin and the functional groups of the second resin are more likely to react with each other, and the compatibility between the first resin and the second resin is more likely to be improved. Note that the content of the modified polyolefin in the first resin may be 100% by mass, but if the melting point of the modified polyolefin is low, there is a risk of a decrease in heat seal strength in a high-temperature environment, so the content is more preferably 40% by mass or less.

[0079] The sealant layer 16 may contain components other than the first resin and the second resin. For example, the sealant layer 16 may contain a component such as an elastomer to impart impact resistance. The sealant layer 16 may also contain additives such as antioxidants, slip agents, flame retardants, antiblocking agents, light stabilizers, dehydrating agents, tackifiers, and nucleating agents to impart sealing properties, heat resistance, and other functionalities.

[0080] The sealant layer 16 may be a single-layer film or a multilayer film, and may be selected depending on the required function. When the sealant layer 16 has a multilayer structure, the layers may be laminated by coextrusion or dry lamination. When the sealant layer 16 has a multilayer structure, it is sufficient that at least one layer contains the first resin and the second resin. However, from the viewpoint of more fully obtaining the effects of the present disclosure, all layers may contain the first resin and the second resin.

[0081] The thickness of the sealant layer 16 (total thickness in the case of multiple layers) is preferably 10 to 150 μm, and more preferably 20 to 100 μm. When the thickness of the sealant layer 16 is 10 μm or more, sufficient heat seal strength can be obtained, and when the thickness is 150 μm or less, the amount of water vapor penetrating from the edge of the packaging material can be reduced.

[0082] The peak melting temperature of the sealant layer varies depending on the application, but in the case of an exterior material for an all-solid-state battery, it is preferably 160 to 280° C. because this improves heat resistance.

[0083] The above describes in detail a preferred embodiment of the exterior packaging material for a power storage device of the present embodiment, but the present disclosure is not limited to such a specific embodiment, and various modifications and variations are possible within the scope of the gist of the present disclosure as set forth in the claims.

[0084] 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.

[0085] While FIG. 1 shows a case in which the barrier layer 13 and the sealant layer 16 are laminated together using the second adhesive layer 12b, as in the packaging material 20 for an electricity storage device shown in FIG. 2, the sealant layer 16 and the barrier layer 13 may be laminated directly together without the second adhesive layer 12b. Even in this case, good adhesion between the sealant layer 16 and the barrier layer 13 can be obtained by including the first resin and the second resin in the sealant layer 16. This is because the second resin, such as polyester or polyamide, has adhesive properties with the barrier layer. Furthermore, when the first resin has a polar group, the adhesion between the sealant layer 16 and the barrier layer 13 can be further improved.

[0086] <Hydrogen sulfide adsorbent> When the packaging materials 10 and 20 of the present embodiment are used in all-solid-state batteries, hydrogen sulfide may be generated by reaction with moisture depending on the type of all-solid-state electrolyte. Therefore, a material that decomposes or adsorbs hydrogen sulfide (a hydrogen sulfide adsorbent) may be added to the packaging materials 10 and 20. The hydrogen sulfide adsorbent may be added to at least one of the first adhesive layer 12a, the second adhesive layer 12b, and the sealant layer 16, for example. When the substrate layer 11 side of the packaging materials 10 and 20 is defined as the outer side and the sealant layer 16 side as the inner side, it is preferable to add the hydrogen sulfide adsorbent to at least one of the layers disposed inside the barrier layer 13, since this facilitates adsorption of hydrogen sulfide generated inside the packaging materials 10 and 20. Adding the hydrogen sulfide adsorbent to the sealant layer 16 is particularly preferable, since this provides a greater effect.

[0087] Examples of hydrogen sulfide adsorbents include zinc oxide, amorphous metal silicates (mainly those containing copper or zinc), hydrates of zirconium and tantanide elements, tetravalent metal phosphates (particularly 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. Among these, zinc oxide is preferred because it more easily neutralizes hydrogen sulfide and is cost-effective and easy to handle. These hydrogen sulfide adsorbents can be used alone or in combination.

[0088] The layer to which the hydrogen sulfide adsorbent is added may be a single layer or multiple layers. When adding the hydrogen sulfide adsorbent to the sealant layer 16, a high-concentration masterbatch may be prepared in advance, and the masterbatch may then be blended into the resin of the sealant layer 16 to achieve an appropriate concentration. When blending the first adhesive layer 12a or the second adhesive layer 12b, if they are formed by coating the adhesive, the masterbatch may be blended directly into the coating liquid. If they are formed by extrusion or the like, the masterbatch may be prepared and blended in, as with the sealant layer 16. Thermoplastic resins such as polyolefin, polyamide, polyester, polycarbonate, polyphenylene ether, polyacetal, polystyrene, polyvinyl chloride, and polyvinyl acetate can be used as the resin for preparing the masterbatch.

[0089] When adding the hydrogen sulfide adsorbing substance, in order to impart dispersibility, sealing property, heat resistance, and other functions, for example, a dispersant, an antioxidant, a slip agent, a flame retardant, an antiblocking agent, a light stabilizer, a dehydrating agent, a tackifier, a crystal nucleating agent, a plasticizer, etc. may be added.

[0090] The content of the hydrogen sulfide adsorbent is preferably 0.01 to 30 mass %, and more preferably 0.1 to 20 mass %, based on the total solid content of the layer to which it is added. If the content of the hydrogen sulfide adsorbent is less than 0.01 mass %, the effect of detoxifying hydrogen sulfide is small, and if it exceeds 30 mass %, the physical properties of the layer to which it is added tend to deteriorate.

[0091] [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.

[0092] 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.

[0093] (Step of Laminating Anti-Corrosion Treatment Layers 14a and 14b on Barrier Layer 13) 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.

[0094] 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.

[0095] 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.

[0096] 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.

[0097] 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.

[0098] 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.

[0099] 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.

[0100] (Step of bonding the base layer 11 and the barrier layer 13) 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.

[0101] (Laminating step of second adhesive layer 12b and sealant layer 16) 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.

[0102] 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, and the solvent is evaporated at a predetermined temperature to form a dry film, or a baking process is performed as necessary after the dry film formation. The sealant layer 16 is then 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.

[0103] 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.

[0104] (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.

[0105] In this manner, the packaging material 10 of this embodiment as shown in FIG. 1 can be manufactured.

[0106] 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.

[0107] The manufacturing method of the packaging material 20 of this embodiment is generally configured to include 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 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 performed in the same manner as the manufacturing method of the packaging material 10 described above.

[0108] (Laminating step of sealant layer 16) This step is a step of forming a sealant layer 16 on the second corrosion prevention treatment layer 14b formed in the previous step. One method for this is to laminate the sealant layer 16 using an extrusion laminator. In forming the sealant layer 16, for example, the components are blended so as to satisfy the above-mentioned structure of the sealant layer 16. The above-mentioned resin composition for forming a sealant layer is used to form the sealant layer 16.

[0109] 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 / sealant layer 16, as shown in Figure 2.

[0110] The sealant layer 16 may be formed by directly extruding, using an extrusion laminator, materials dry-blended to achieve the composition described above as the constituent components of the resin composition for forming a sealant layer. Alternatively, the sealant layer 16 may be formed by extruding, using an extrusion laminator, a granulated product that has been melt-blended in advance using a melt-kneading device such as a single-screw extruder, a twin-screw extruder, or a Brabender mixer. From the viewpoint of productivity, the formation speed (processing speed) of the sealant layer 16 may be, for example, 80 m / min or more.

[0111] (Heat treatment process) This step involves heat treating the laminate. Heat treating the laminate can improve adhesion between the barrier layer 13, the second corrosion prevention treatment layer 14b, and the sealant layer 16. The heat treatment is preferably carried out at a temperature at least equal to or higher than the melting point of the sealant layer 16.

[0112] In this manner, the exterior packaging material 20 of this embodiment as shown in FIG. 2 can be manufactured.

[0113] The above describes in detail preferred embodiments of the exterior packaging material for a power storage device of the present disclosure, but the present disclosure is not limited to such specific embodiments, and various modifications and variations are possible within the scope of the gist of the present disclosure as set forth in the claims.

[0114] The packaging material for an electricity storage device according to the present disclosure can be suitably used as a packaging material for an electricity storage device such as, for example, a secondary battery such as a lithium ion battery, a nickel-metal hydride battery, or a lead-acid battery, and an electrochemical capacitor such as an electric double layer capacitor. In particular, the packaging material for an electricity storage device according to the present disclosure can maintain excellent heat sealability even when used in a high-temperature environment after heat sealing, and is therefore suitable as a packaging material for an all-solid-state battery using a solid electrolyte that is expected to be used in such an environment.

[0115] [Electricity storage device] FIG. 3 is a perspective view showing one embodiment of an electricity storage device fabricated using the above-described exterior material. As shown in FIG. 3, the electricity storage device 50 includes a battery element (electricity storage device main body) 52 including electrodes, two metal terminals (leads, current extraction terminals) 53 extending from the electrodes for extracting current from the battery element 52 to the outside, and an exterior material 10 that hermetically encases the battery element 52. The exterior material 10 is the exterior material 10 according to the above-described embodiment and is used as a container for accommodating the battery element 52. In the exterior material 10, the base 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 element 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 layer 11 is on the exterior side of the electricity storage device 50 and the sealant layer 16 is on the interior side of the electricity storage device 50. Metal terminal 53 is sandwiched and sealed by exterior material 10 that forms a container with sealant layer 16 on the inside. Metal terminal 53 may be sandwiched by exterior material 10 via a tab sealant. Note that in electricity storage device 50, exterior material 20 may be used instead of exterior material 10.

[0116] Battery element 52 has an electrolyte interposed between a positive electrode and a negative electrode. Metal terminal 53 is a part of the current collector that is taken out from exterior packaging 10, and is made of metal foil such as copper foil or aluminum foil.

[0117] The electricity storage device 50 of this embodiment may be an all-solid-state battery. In this case, a solid electrolyte such as a sulfide-based solid electrolyte is used as the electrolyte of the battery element 52. The electricity storage device 50 of this embodiment uses the packaging material 10 of this embodiment, and therefore can ensure excellent heat seal strength in a high-temperature environment (e.g., 150°C), as well as excellent heat seal strength in a room temperature environment after being exposed to a high-temperature environment. [Example]

[0118] Hereinafter, the present disclosure will be described more specifically based on examples, but the present disclosure is not limited to the following examples.

[0119] [Materials used] The materials used in the examples and comparative examples are shown below.

[0120] <Base layer (thickness 25 μm)> A polyethylene terephthalate film was used, one side of which had been subjected to a corona treatment.

[0121] <First adhesive layer (thickness 4 μm)> A polyurethane adhesive (manufactured by Toyo Ink Co., Ltd.) containing a polyester polyol-based base resin and a tolylene diisocyanate adduct curing agent was used.

[0122] <First corrosion prevention treatment layer (base layer side) and second corrosion prevention treatment layer (sealant layer side)> (CL-1): "Sodium polyphosphate-stabilized cerium oxide sol" was used, adjusted to a solids concentration of 10% by mass using distilled water as the solvent. The sodium polyphosphate-stabilized cerium oxide sol was obtained by blending 100 parts by mass of cerium oxide with 10 parts by mass of sodium phosphate. (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. (CL-3): A 1% by mass aqueous solution of phosphoric acid was used as the solvent. The solid content of the water-soluble phenolic resin (manufactured by Sumitomo Bakelite Co., Ltd.) was adjusted to 1% by mass. Chromium fluoride (CrF3) was added to the resin at a concentration of 10 mg / m2, with the amount of Cr present in the final dried film. 2 The chemical conversion treatment agent was used with its concentration adjusted so that

[0123] <Barrier layer (thickness: 40 μm)> Annealed and degreased soft aluminum foil (manufactured by Toyo Aluminum Co., Ltd., "8079 material") was used.

[0124] <Second adhesive layer (thickness 3 μm)> An epoxy adhesive was used, prepared by diluting a mixture of 100 parts by mass of epoxy resin (manufactured by Adeka Corporation, product name: EP4100) and 25 parts by mass of polyamidoamine curing agent (manufactured by Adeka Corporation, product name: EH4602) with ethyl acetate to a solids content of 30% by mass.

[0125] <Sealant layer (thickness: 80 μm)> The first resin and the second resin shown in Table 1 were prepared. The first resin and the second resin were melt-blended in advance using a twin-screw kneader to form a resin composition for forming a sealant layer. The compositions of the resin compositions for forming a sealant layer (the resins used and their blending amounts) are shown in Tables 2 to 6. The blending amount unit "%" in the tables refers to "% by mass" based on the mass of the total amount of the first resin and the second resin (100% by mass). The modified polyolefins were those modified with the acid anhydrides shown in the Name column, or those having polar groups shown in the same column.

[0126] [Table 1]

[0127] <Hydrogen sulfide adsorbent> In some examples and comparative examples, zinc oxide (manufactured by Sakai Chemical Industry Co., Ltd.) was added as a hydrogen sulfide adsorbent to the sealant layer or the second adhesive layer. Whether or not it was added is shown in Tables 2 to 6. When added to the sealant layer, the amount added was 3 parts by mass per 100 parts by mass of the total of the first resin and the second resin. When the sealant layer was multi-layered, the above amount was added to both layers. When added to the second adhesive layer, the amount added was 3 parts by mass per 100 parts by mass of the total of the epoxy resin and the curing agent. The hydrogen sulfide adsorbent was mixed with the materials constituting each layer.

[0128] [Fabrication of exterior materials] (Examples 1 to 3) The barrier layer was attached to the base layer by dry lamination using a polyurethane adhesive (first adhesive layer). The barrier layer and base layer were laminated by applying a polyurethane adhesive to one side of the barrier layer so that the thickness after curing was 4 μm, drying it at 80°C for 1 minute, laminating it with the base layer, and aging it at 60°C for 5 days.

[0129] Next, the side of the barrier layer opposite the substrate layer was attached to the sealant layer using an epoxy adhesive (second adhesive layer) by dry lamination. The barrier layer and sealant layer were laminated by applying an epoxy adhesive to the surface of the barrier layer opposite the substrate layer so that the thickness after curing would be 3 μm, drying at 80°C for 1 minute, laminating it with the sealant layer, and aging it at 120°C for 3 hours. The sealant layer was prepared by previously casting the resin composition for forming the sealant layer shown in Table 2 into a film. Using the above method, an exterior material (a laminate of substrate layer / first adhesive layer / barrier layer / second adhesive layer / sealant layer) was produced.

[0130] Examples 4 to 14 First, first and second corrosion prevention treatment layers were formed on the barrier layer by the following procedure: (CL-1) was applied to both surfaces of the barrier layer in a dry coating amount of 70 mg / m 2 The 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 By applying the coating by microgravure coating so that the coating was as follows, a composite layer consisting of (CL-1) and (CL-2) was formed as the first and second corrosion prevention treatment layers. This composite layer exhibits corrosion prevention performance by combining the two types of (CL-1) and (CL-2).

[0131] Next, the first corrosion prevention treatment layer side of the barrier layer provided with the first and second corrosion prevention treatment layers was attached to the base layer by dry lamination using a polyurethane adhesive (first adhesive layer). The lamination of the barrier layer and base layer was performed by applying a polyurethane adhesive to the surface of the barrier layer facing the first corrosion prevention treatment layer so that the thickness after curing would be 4 μm, drying at 80°C for 1 minute, laminating it to the base layer, and aging it at 60°C for 5 days.

[0132] Next, the second corrosion prevention treatment layer side of the barrier layer provided with the first and second corrosion prevention treatment layers was attached to the sealant layer by dry lamination using an epoxy-based adhesive (second adhesive layer). The barrier layer and sealant layer were laminated by applying an epoxy-based adhesive to the surface of the barrier layer opposite the substrate layer to a thickness of 3 μm after curing, drying at 80°C for 1 minute, laminating it to the sealant layer, and aging at 120°C for 3 hours. The sealant layer was a pre-cast film of the resin composition for forming the sealant layer shown in Table 2. Using the above method, 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. A hydrogen sulfide adsorbent was added to the second adhesive layer in Example 12, and to the sealant layer in the other Examples.

[0133] Example 15 An exterior material (a laminate of substrate layer / first adhesive layer / barrier layer / second adhesive layer / sealant layer) was produced in the same manner as in Example 11, except that no anti-corrosion treatment layer was provided.

[0134] Example 16 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 11, except that no hydrogen sulfide adsorbing substance was added to the sealant layer.

[0135] (Examples 17 to 23) 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 11, except that the composition of the resin composition for forming the sealant layer was changed as shown in Table 3.

[0136] Example 24 The first and second corrosion prevention treatment layers were formed by the following procedure: (CL-3) was applied to both surfaces of the barrier layer in a dry coating amount of 30 mg / m 2 The 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 By applying the coating by microgravure coating so that the coating was as follows, composite layers consisting of (CL-3) and (CL-2) were formed as first and second corrosion prevention treatment layers. This composite layer exhibits corrosion prevention performance by combining the two types of (CL-3) and (CL-2). 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 11, except that a barrier layer provided with the first and second corrosion prevention treatment layers was used.

[0137] (Examples 25 to 27) In the same manner as in Example 11, the barrier layer provided with the first and second corrosion prevention treatment layers and the substrate layer were laminated using a polyurethane adhesive (first adhesive layer). Next, this was set in the unwinding section of an extrusion laminator, and a sealant layer (thickness: 80 μm) was extrusion laminated onto the second corrosion prevention treatment layer at 270°C and 100 m / min. For the sealant layer, various materials were compounded in advance using a twin-screw extruder, and the compound was used for the extrusion lamination after undergoing water cooling and pelletizing processes. The resin composition for forming the sealant layer shown in Table 4 was used to form the sealant layer.

[0138] The laminate thus obtained was subjected to a heat treatment so that the maximum temperature of the laminate reached was 220°C, thereby producing 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).

[0139] (Examples 28 to 30 and 33) 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 11, except that the composition of the resin composition for forming the sealant layer was changed as shown in Table 4.

[0140] (Examples 31 to 32 and 34) 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 26, except that the composition of the resin composition for forming the sealant layer was changed as shown in Table 4.

[0141] (Examples 35 and 38-39) In the same manner as in Example 11, a barrier layer provided with first and second corrosion prevention treatment layers and a substrate layer were laminated using a polyurethane adhesive (first adhesive layer). Next, the second corrosion prevention treatment layer side of the barrier layer provided with the first and second corrosion prevention treatment layers was attached to a sealant layer by dry lamination using an epoxy adhesive (second adhesive layer). The barrier layer and sealant layer were laminated by applying an epoxy adhesive to the surface of the barrier layer opposite the substrate layer to a thickness of 3 μm after curing, drying at 80°C for 1 minute, laminating the layer to the sealant layer, and aging at 120°C for 3 hours. The sealant layer was a multilayer cast film (thickness of each layer: 40 μm) previously formed using the resin composition for forming a barrier layer and the resin composition for forming an innermost layer, as shown in Table 5. Using the above method, 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 (barrier layer-side sealant layer and innermost layer-side sealant layer)) was produced. The hydrogen sulfide adsorbing substance was added to both of the two sealant layers.

[0142] (Examples 36 to 37 and 40) In the same manner as in Example 11, the barrier layer provided with the first and second corrosion prevention treatment layers and the substrate layer were laminated using a polyurethane adhesive (first adhesive layer). The resulting laminate was then set in the unwinding section of an extrusion laminator, and co-extruded onto the second corrosion prevention treatment layer at 270°C and 100 m / min to form two sealant layers (each 40 μm thick). For the sealant layer, various materials were compounded in advance using a twin-screw extruder, and the compound was subjected to water cooling and pelletizing processes before being used in the extrusion lamination. The resin composition for forming the barrier layer and the resin composition for forming the innermost sealant layer shown in Table 5 were used to form the sealant layer.

[0143] The laminate thus obtained was subjected to a heat treatment so that the maximum temperature of the laminate reached was 220°C, thereby producing 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 (barrier layer-side sealant layer and innermost layer-side sealant layer)). The hydrogen sulfide adsorbing substance was added to both of the two sealant layers.

[0144] (Examples 41 to 42) 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 11, except that the composition of the resin composition for forming a sealant layer was changed as shown in Table 5.

[0145] (Comparative Examples 1 to 2, 4 and 6) 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 11, except that the composition of the resin composition for forming a sealant layer was changed as shown in Table 6.

[0146] (Comparative Examples 3 and 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 26, except that the composition of the resin composition for forming the sealant layer was changed as shown in Table 6.

[0147] [Measurement of crystallinity after heat sealing] Two exterior materials using polyester or polyamide as the second resin were prepared, laminated with the sealant layers facing each other, and heat-sealed at 260°C, 0.5 MPa, and for 3 seconds. After cooling to 25°C, the crystallinity of the polyester and polyamide in the sealant layer was measured. The crystallinity was calculated using IR from the area ratio of the crystalline peak to the (amorphous peak + crystalline peak).

[0148] [Measurement of room temperature heat seal strength] A 60mm x 120mm sample of packaging material was cut and folded in half, and one side was heat-sealed with a 10mm-wide sealing bar at 220°C, 0.5 MPa, and 3 seconds. The heat-sealed packaging material was aged at 150°C for 60 minutes and then cooled to room temperature. The heat-sealed area was cut into 15mm widths (see Figure 4), and the seal strength (T-peel strength) was measured using an Instron testing machine. The test was conducted in accordance with JIS K6854 at 23°C, 50% RH, and a peel rate of 50mm / min. The measured seal strength (burst strength) was evaluated according to the following criteria. A rating of C or higher was considered a pass. A: Seal strength is 40N / 15mm or more B: Seal strength is 30N / 15mm or more and less than 40N / 15mm C: Seal strength is 25N / 15mm or more and less than 30N / 15mm D: Seal strength is less than 25N / 15mm

[0149] Furthermore, by comparing the seal strength before and after 150°C aging (hereinafter sometimes referred to as "150°C AG"), the rate of decrease in seal strength was calculated according to the following formula. Decrease rate (%) = {(seal strength before AG at 150°C - seal strength after AG at 150°C) / seal strength before AG at 150°C} x 100

[0150] [Measurement of high-temperature heat seal strength] A sample of the packaging material was cut to 60mm x 120mm, folded in half, and one side was heat-sealed at 220°C, 0.5MPa, and 3 seconds using a 10mm-wide sealing bar. The heat-sealed area was then cut to a 15mm width (see Figure 4) and left to stand for 5 minutes in a 150°C environment. The seal strength (T-peel strength) was then measured at a peel rate of 50mm / min in a 150°C environment using a testing machine (manufactured by Instron). The measured seal strength (burst strength) was evaluated according to the following criteria. A rating of C or higher was considered a pass. A: Seal strength is 35N / 15mm or more B: Seal strength is 30N / 15mm or more and less than 35N / 15mm C: Seal strength is 20N / 15mm or more and less than 30N / 15mm D: Seal strength is less than 20N / 15mm

[0151] [Measurement of room temperature heat seal strength after H2S exposure] A 60mm x 120mm sample of packaging material was cut and folded in half. One side was heat-sealed with a 10mm-wide seal bar at 220°C, 0.5 MPa, and 3 seconds. The heat-sealed area was then cut into 15mm widths (see Figure 4) and left to stand at room temperature for 72 hours in an environment with a hydrogen sulfide concentration of 20 ppm by mass. After standing at room temperature for 5 minutes, the seal strength (T-peel strength) of the heat-sealed area was measured using a testing machine (manufactured by Instron). The test was conducted in accordance with JIS K6854 at 23°C, 50% RH, and a peel speed of 50 mm / min. The measured seal strength (burst strength) was evaluated according to the following criteria. A: Seal strength is 50N / 15mm or more B: Seal strength is 40N / 15mm or more and less than 50N / 15mm C: Seal strength is 35N / 15mm or more and less than 50N / 15mm D: Seal strength is less than 35N / 15mm

[0152] [Measurement of high-temperature heat seal strength after H2S exposure] A 60mm x 120mm sample of the packaging material was folded in half and one side was heat-sealed at 220°C, 0.5 MPa, and 3 seconds using a 10mm-wide sealing bar. The heat-sealed area was then cut into 15mm widths (see Figure 4) and left to stand at room temperature for 72 hours in an environment with a hydrogen sulfide concentration of 20 ppm by mass. After leaving the sample to stand for 5 minutes in an environment at 150°C, the seal strength (T-peel strength) was measured at a peel rate of 50 mm / min in an environment at 150°C using a testing machine (manufactured by Instron). The measured seal strength (burst strength) was evaluated according to the following criteria. A: Burst strength is 35N / 15mm or more B: Burst strength is 30N / 15mm or more and less than 35N / 15mm C: Burst strength is 20N / 15mm or more and less than 30N / 15mm D: Burst strength is less than 20N / 15mm

[0153] [Table 2]

[0154] [Table 3]

[0155] [Table 4]

[0156] [Table 5]

[0157] [Table 6] [Industrial Applicability]

[0158] According to the present disclosure, there are provided an exterior packaging material for a storage battery device that can ensure excellent heat seal strength in a high-temperature environment (e.g., 150°C) and can suppress a decrease in heat seal strength in a room temperature environment after use in a high-temperature environment (e.g., 150°C), and an electricity storage device using the same. [Explanation of symbols]

[0159] 10, 20...outer packaging material for electricity storage device, 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, 16...sealant layer, 50...electricity storage device, 52...battery element, 53...metal terminal.

Claims

[Claim 1] An outer packaging material for an electricity storage device comprising at least a base layer, a barrier layer, and a sealant layer in this order, The sealing layer comprises a first resin that is a polyolefin, and a second resin that is at least one resin selected from the group consisting of polyester, polyamide, polycarbonate, and polyphenylene ether.

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