Packaging material for power storage device, power storage device, and power storage apparatus

Abstract

To provide an exterior material for a power storage device capable of effectively adsorbing hydrogen sulfide, and to provide a power storage device and power storage equipment.SOLUTION: A packaging material for a power storage device comprising a hydrogen sulfide adsorption layer containing a hydrogen sulfide adsorbent, a substrate layer, a metal foil layer, and a sealant layer in this order, wherein the hydrogen sulfide adsorbent comprises a metal oxide, and a content of the hydrogen sulfide adsorbent in the hydrogen sulfide adsorption layer is 0.5% by mass or more.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an exterior material for an electricity storage device, an electricity storage device, and an electricity storage apparatus. [Background technology]

[0002] In an electricity storage device such as an all-solid-state battery, an electricity storage element having a sulfide-based solid electrolyte is housed in an exterior bag formed using an exterior material.

[0003] Sulfide-based solid electrolytes react with moisture in the air to produce toxic hydrogen sulfide, so countermeasures are necessary. For example, measures have been taken to improve the moisture barrier properties of the exterior packaging to prevent moisture from the air from penetrating the inside of the exterior bag. As an exterior material for forming such an exterior bag, for example, Patent Document 1 listed below discloses a laminate sheet for a sulfide-based all-solid-state battery, which has, in this order, a base layer, a barrier layer, a moisture absorption layer containing a moisture absorbent, and a sulfide-based gas absorption layer containing a hydrogen sulfide absorbent. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-187855 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the laminate sheet for a sulfide-based all-solid-state battery described in Patent Document 1 has room for improvement in terms of adsorption of hydrogen sulfide.

[0006] The present disclosure has been made in view of the above circumstances, and has an object to provide an exterior material for an electricity storage device, an electricity storage device, and an electricity storage apparatus that can effectively adsorb hydrogen sulfide. [Means for solving the problem]

[0007] One aspect of the present disclosure provides an exterior packaging material for an electricity storage device, comprising, in this order, a hydrogen sulfide adsorption layer containing a hydrogen sulfide adsorbent, a substrate layer, a metal foil layer, and a sealant layer, wherein the hydrogen sulfide adsorbent is made of a metal oxide, and the content of the hydrogen sulfide adsorbent in the hydrogen sulfide adsorption layer is 0.5 mass% or more.

[0008] The above-described packaging material for an electricity storage device (hereinafter also simply referred to as "packaging material") has the above configuration, so that when hydrogen sulfide permeates the packaging material, the hydrogen sulfide can be effectively adsorbed by the hydrogen sulfide adsorbent in the hydrogen sulfide adsorption layer. Therefore, this packaging material can prevent hydrogen sulfide generated in an outer packaging bag formed using the packaging material from leaking to the outside of the packaging material. Furthermore, because the hydrogen sulfide adsorption layer is located on the opposite side of the sealant layer from the metal foil layer, even if water is generated as a result of the adsorption reaction of hydrogen sulfide by the hydrogen sulfide adsorbent, the water does not easily permeate the metal foil layer. This prevents water from penetrating into the outer packaging bag formed using the packaging material, and therefore prevents hydrogen sulfide from being generated by a reaction between water and the solid electrolyte even when a solid electrolyte is disposed in the outer packaging bag.

[0009] In the packaging material for a power storage device, it is preferable that the base material layer contains a hydrogen sulfide adsorbent, and that the hydrogen sulfide adsorbent is made of a metal oxide. In this case, since the hydrogen sulfide adsorbent is contained not only in the hydrogen sulfide adsorption layer but also in the base material layer, when hydrogen sulfide permeates the packaging material, it is adsorbed not only by the hydrogen sulfide adsorbent in the hydrogen sulfide adsorption layer but also by the hydrogen sulfide adsorbent in the base material layer, thereby enabling the packaging material for an electricity storage device to more effectively adsorb hydrogen sulfide.

[0010] In the packaging material for a power storage device, the content of the hydrogen sulfide adsorbent in the base material layer is preferably 0.5 mass % or more. In this case, hydrogen sulfide is effectively adsorbed by the hydrogen sulfide adsorbent in the substrate layer, and therefore hydrogen sulfide is effectively adsorbed by the exterior material.

[0011] In the packaging material for a power storage device, at least one of the hydrogen sulfide adsorption layer and the base material layer preferably further contains a color developer that changes color upon reaction with hydrogen sulfide, and the color developer preferably comprises a metal salt of an acid. In this case, if the amount of hydrogen sulfide that permeates the packaging material becomes excessive, the color developer in the hydrogen sulfide adsorption layer and the base layer containing the color developer begins to discolor due to reaction with hydrogen sulfide. The discoloration of the color developer indicates that the hydrogen sulfide adsorbent can no longer adsorb hydrogen sulfide and that the packaging material can no longer be used. This makes it easier to determine whether the packaging material can be continued.

[0012] In the packaging material for a power storage device, the total content of the hydrogen sulfide adsorbent and the color developer in the hydrogen sulfide adsorption layer or the base material layer is preferably 30 mass % or less. When the total content in the hydrogen sulfide adsorption layer or the substrate layer is 30 mass % or less, the hydrogen sulfide adsorption layer or the substrate layer is less likely to become brittle.

[0013] In the packaging material for a power storage device, the metal oxide preferably includes an oxide of a divalent metal. In this case, hydrogen sulfide can be adsorbed more effectively.

[0014] In the packaging material for a power storage device, the hydrogen sulfide adsorption layer is preferably obtained using a coating liquid containing the hydrogen sulfide adsorbent. In this case, the hydrogen sulfide adsorption layer can be easily formed regardless of the type of hydrogen sulfide adsorbent contained in the coating liquid.

[0015] In the packaging material for a power storage device, it is preferable that the coating liquid further contains a binder resin, and that the binder resin contains at least one of an acrylic resin and a urethane resin. In this case, the coating liquid contains a binder resin, which fixes the hydrogen sulfide adsorbent in the hydrogen sulfide adsorption layer and makes the hydrogen sulfide adsorbent less likely to fall off. Furthermore, the binder resin contains at least one of a urethane resin and an acrylic resin, which improves the chemical resistance of the hydrogen sulfide adsorption layer and the chemical resistance of the packaging material.

[0016] In the packaging material for a power storage device, the sealant layer preferably contains a resin but does not contain a hydrogen sulfide adsorbent. In this case, gaps are not formed between the resin and the hydrogen sulfide adsorbent contained in the sealant layer due to poor compatibility between them, improving moisture barrier properties. Furthermore, since the sealant layer does not contain a hydrogen sulfide adsorbent, which is a foreign substance to the resin, heat seal strength can be increased.

[0017] The packaging material for a power storage device preferably further includes an adhesive layer between the base material layer and the metal foil layer. In this case, the adhesive layer improves the adhesion between the substrate layer and the metal foil layer, thereby suppressing delamination in the packaging material.

[0018] Another aspect of the present disclosure provides an electricity storage device including an outer bag and an electricity storage element housed in the outer bag, wherein the outer bag is obtained using the electricity storage device exterior material, the hydrogen sulfide adsorption layer of the electricity storage device exterior material is the outermost layer, and the electricity storage element contains an electrolyte.

[0019] According to the above-described electricity storage device, even if hydrogen sulfide is generated inside the outer bag, the hydrogen sulfide can be effectively adsorbed by the hydrogen sulfide adsorbent in the hydrogen sulfide adsorption layer as the hydrogen sulfide permeates through the outer bag. Therefore, this electricity storage device can prevent hydrogen sulfide generated inside the outer bag from leaking to the outside of the outer bag. Furthermore, because the hydrogen sulfide adsorption layer is located on the opposite side of the sealant layer from the metal foil layer, even if water is generated as a result of the adsorption reaction of hydrogen sulfide by the hydrogen sulfide adsorbent, the water does not easily permeate the metal foil layer, making it difficult for the water to enter the outer bag. This prevents the electrolyte in the electricity storage element housed inside the outer bag from coming into contact with water, thereby preventing the generation of hydrogen sulfide due to the reaction between water and the electrolyte.

[0020] The electricity storage device is particularly useful when the electrolyte is a solid electrolyte (i.e., when it is an all-solid-state battery). When the electricity storage device is an all-solid-state battery, the electricity storage element may react with moisture to generate hydrogen sulfide inside the outer bag, but even in this case, the hydrogen sulfide is effectively adsorbed by the hydrogen sulfide adsorbent in the hydrogen sulfide adsorption layer as it passes through the outer bag, and leakage of hydrogen sulfide to the outside of the outer bag can be suppressed.

[0021] Yet another aspect of the present disclosure provides an electric storage device including a plurality of electric storage devices and a housing that houses the plurality of electric storage devices, wherein the electric storage devices are the electric storage devices described above.

[0022] By virtue of the above configuration, even if hydrogen sulfide is generated in each of the electricity storage devices, the hydrogen sulfide can be effectively adsorbed by the hydrogen sulfide adsorbent in the hydrogen sulfide adsorption layer as the hydrogen sulfide permeates the exterior bag. Therefore, this electricity storage device can prevent hydrogen sulfide generated in each of the electricity storage devices from leaking from inside the electricity storage device into the space between the housing and the electricity storage device. Furthermore, in this electricity storage device, the hydrogen sulfide adsorption layer is located on the opposite side of the metal foil layer from the sealant layer in the exterior bag of the electricity storage device. Therefore, even if a malfunction of one of the electricity storage devices causes hydrogen sulfide to leak from the exterior bag of that electricity storage device into the space between the electricity storage device and the housing, the hydrogen sulfide can be effectively adsorbed by the hydrogen sulfide adsorption layers of the exterior bags of the other electricity storage devices, preventing hydrogen sulfide from leaking outside the housing. [Effects of the Invention]

[0023] According to the present disclosure, there are provided an exterior packaging material for an electricity storage device, an electricity storage device, and an electricity storage device that can effectively adsorb hydrogen sulfide. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 1 is a cross-sectional view that schematically shows one embodiment of an exterior packaging material for an electricity storage device according to the present disclosure. [Figure 2] FIG. 2 is a perspective view schematically illustrating an embodiment of the power storage device of the present disclosure. [Figure 3]FIG. 3 is a cross-sectional view schematically showing an embodiment of the power storage device of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0025] 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.

[0026] [Exterior materials for energy storage devices] Fig. 1 is a cross-sectional view schematically illustrating an electrical storage device packaging material according to an embodiment of the present disclosure. As shown in Fig. 1, packaging material 10 of this embodiment is a packaging material used in an electrical storage device, and includes a hydrogen sulfide adsorption layer 17, a base material layer 11, a metal foil layer 13, and a sealant layer 16, in this order. The hydrogen sulfide adsorbent (hereinafter also simply referred to as "adsorbent") in the hydrogen sulfide adsorption layer 17 is 0.5 mass % or more. As shown in FIG. 1, the exterior packaging material 10 may also include a first adhesive layer 12 between the base material layer 11 and the metal foil layer 13, and a second adhesive layer 15 between the metal foil layer 13 and the sealant layer 16.

[0027] When hydrogen sulfide permeates the packaging material 10, the hydrogen sulfide can be effectively adsorbed by the hydrogen sulfide adsorbent in the hydrogen sulfide adsorption layer 17. Therefore, the packaging material 10 can prevent hydrogen sulfide generated inside an outer packaging bag formed using the packaging material 10 from leaking out to the outside of the packaging material 10. Furthermore, since the hydrogen sulfide adsorption layer 17 is located on the opposite side of the sealant layer 16 relative to the metal foil layer 13, even if water is generated as a result of the adsorption reaction of hydrogen sulfide by the hydrogen sulfide adsorbent, the moisture is unlikely to permeate the metal foil layer 13, and therefore moisture is unlikely to penetrate into the exterior bag formed using the exterior material 10. This prevents the electrolyte in the storage element housed in the exterior bag from coming into contact with moisture, thereby suppressing the generation of hydrogen sulfide due to the reaction between moisture and the electrolyte.

[0028] The metal foil layer 13 may have a first corrosion prevention treatment layer 14a on the substrate layer 11 side, and may have a second corrosion prevention treatment layer 14b on the sealant layer 16 side. When packaging material 10 is used as an outer bag for an electricity storage device, hydrogen sulfide adsorption layer 17 is the outermost layer and sealant layer 16 is the innermost layer in packaging material 10. In other words, packaging material 10 is used with hydrogen sulfide adsorption layer 17 facing the outside of the electricity storage device and sealant layer 16 facing the inside of the electricity storage device.

[0029] Each layer that constitutes the packaging material 10 will now be described in detail.

[0030] <Hydrogen sulfide adsorption layer> The hydrogen sulfide-adsorbing layer 17 is a layer that adsorbs hydrogen sulfide and contains a hydrogen sulfide adsorbent. The hydrogen sulfide-adsorbing layer 17 is obtained using a resin composition for forming a hydrogen sulfide-adsorbing layer that contains a hydrogen sulfide adsorbent.

[0031] The hydrogen sulfide adsorbent is made of a metal oxide that adsorbs hydrogen sulfide. Examples of metal oxides include oxides of monovalent metals such as silver oxide, oxides of divalent metals such as zinc oxide, calcium oxide, copper oxide, lead oxide, manganese oxide, nickel oxide, cobalt oxide, tin oxide, and cadmium oxide, oxides of trivalent metals, and oxides of tetravalent metals. Among these, the hydrogen sulfide adsorbent is preferably an oxide of a divalent metal, which can adsorb hydrogen sulfide more effectively. The divalent metal oxide is particularly preferably zinc oxide, which can adsorb hydrogen sulfide even more effectively.

[0032] The hydrogen sulfide adsorbent may be a non-conductive hydrogen sulfide adsorbent as described above, or may be a conductive hydrogen sulfide adsorbent, such as conductive zinc oxide.

[0033] The content of the hydrogen sulfide adsorbent in the hydrogen sulfide adsorption layer 17 may be 0.5% by mass or more, or may be 1% by mass or more, 5% by mass or more, 10% by mass or more, or 15% by mass or more. When the content is 0.5 mass % or more, hydrogen sulfide is effectively adsorbed by the hydrogen sulfide adsorbent in the hydrogen sulfide adsorption layer 17, and therefore hydrogen sulfide is effectively adsorbed by the exterior packaging material 10. The content may be 30% by mass or less, or 20% by mass or less, in which case the hydrogen sulfide absorbing layer 17 is less likely to become brittle.

[0034] The hydrogen sulfide absorbing layer 17 may or may not further contain a color developer that changes color upon reaction with hydrogen sulfide. When the hydrogen sulfide adsorption layer 17 contains a color developer, if the amount of hydrogen sulfide that permeates the packaging material 10 becomes excessive, the color developer in the hydrogen sulfide adsorption layer 17 will begin to discolor due to a reaction with hydrogen sulfide. The discoloration of the color developer is an indication that the hydrogen sulfide adsorbent can no longer adsorb hydrogen sulfide and that the packaging material 10 can no longer be used. This makes it easier to determine whether the packaging material 10 can be continued to be used. Furthermore, when the hydrogen sulfide adsorption layer 17 contains a color developer, it is easy to visually confirm that the color developer has reacted with hydrogen sulfide and discolored in an packaging bag obtained using the packaging material 10 and with the hydrogen sulfide adsorption layer 17 as the outermost layer.

[0035] The color developer is a material that changes color upon reaction with hydrogen sulfide and is made of a metal salt of an acid. The acid may be an organic acid or an inorganic acid, such as acetic acid, or an inorganic acid. Examples of metals include monovalent metals such as silver, and divalent metals such as lead and copper. Examples of metal salts of acids include lead acetate, silver sulfate, and copper sulfate, which can be used either alone or in combination of two or more.

[0036] The content of the color developer in the hydrogen sulfide adsorption layer 17 may be 0.01% by mass or more, 0.1% by mass or more, 0.5% by mass or more, 1% by mass or more, or 5% by mass or more. When the content is 0.01% by mass or more, if the developer reacts with hydrogen sulfide and discolors, the discoloration of the hydrogen sulfide adsorption layer 17 becomes more pronounced, making it possible to more reliably determine whether or not the developer has reacted with hydrogen sulfide. The content may be 30% by mass or less, 20% by mass or less, 15% by mass or less, or 10% by mass or less, in which case the hydrogen sulfide adsorption layer 17 is less likely to become brittle.

[0037] The total content of the hydrogen sulfide adsorbent and the color developer in the hydrogen sulfide adsorption layer 17 may be 60% by mass or less, 50% by mass or less, 40% by mass or less, 30% by mass or less, 20% by mass or less, 15% by mass or less, or 10% by mass or less. In particular, the total content is preferably 30 mass % or less, which makes the hydrogen sulfide adsorption layer 17 less brittle. Furthermore, when the hydrogen sulfide adsorption layer 17 contains a resin, a decrease in the proportion of the resin further prevents the deterioration of the role and function that the resin originally has. The total content is 0.5% by mass or more. The total content may be 1% by mass or more, 3% by mass or more, or 5% by mass or more. When the total content is 1% by mass or more, hydrogen sulfide can be effectively adsorbed.

[0038] The resin composition for forming the hydrogen sulfide adsorption layer 17 may contain a catalyst that increases the reactivity of the components in the resin composition for forming the hydrogen sulfide adsorption layer, or may further contain a catalyst and a reaction retarder. The catalyst may be, for example, a urethanization catalyst, and the reaction retarder may be, for example, acetylacetone.

[0039] The hydrogen sulfide adsorption layer 17 may further contain various additives, such as a flame retardant, a slip agent, an antiblocking agent, an antioxidant, a light stabilizer, a dehydrating agent, a crystal nucleating agent, and a tackifier, as needed.

[0040] The hydrogen sulfide adsorption layer 17 may be in the form of a coating film, or in the form of a stretched or unstretched film.

[0041] When the hydrogen sulfide-adsorbing layer 17 is a coating film, the hydrogen sulfide-adsorbing layer 17 is obtained by using a coating liquid containing a hydrogen sulfide adsorbent as a resin composition for forming the hydrogen sulfide-adsorbing layer. In this case, the hydrogen sulfide-adsorbing layer 17 can be easily formed regardless of the type or amount of the hydrogen sulfide adsorbent contained in the coating liquid or the thickness of the hydrogen sulfide-adsorbing layer 17. The hydrogen sulfide adsorption layer 17 can be formed by coating a coating liquid containing a hydrogen sulfide adsorbent once or for the number of times the hydrogen sulfide adsorption layer 17 is laminated.

[0042] The coating liquid containing the hydrogen sulfide adsorbent may further contain a binder resin, which fixes the hydrogen sulfide adsorbent in the hydrogen sulfide adsorbing layer 17 and makes the hydrogen sulfide adsorbent less likely to fall off. The binder resin is not particularly limited, and examples of the binder resin include acrylic resin, urethane resin, polyester resin, polyamide resin, polyimide resin, polyamideimide resin, polyether ketone resin, polyphenylene sulfide resin, polyetherimide resin, polysulfone resin, fluororesin, phenol resin, melamine resin, allyl resin, silicone resin, epoxy resin, furan resin, and acetyl cellulose resin. The binder resin preferably contains at least one of an acrylic resin and a urethane resin, which can improve the chemical resistance of the hydrogen sulfide adsorption layer 17 and the chemical resistance of the packaging material 10.

[0043] When the hydrogen sulfide-adsorbing layer 17 is a stretched or unstretched film, the resin composition for forming the hydrogen sulfide-adsorbing layer contains a hydrogen sulfide adsorbent and a binder resin. Examples of binder resins include acrylic resins, urethane resins, polyester resins, polyamide resins, polyimide resins, polyamideimide resins, polyether ketone resins, polyphenylene sulfide resins, polyetherimide resins, polysulfone resins, fluororesins, phenolic resins, melamine resins, allyl resins, silicone resins, epoxy resins, furan resins, and acetyl cellulose resins. From the viewpoint of improving the chemical resistance of the hydrogen sulfide adsorption layer 17, the binder resin preferably contains at least one of a urethane resin and an acrylic resin.

[0044] The thickness of the hydrogen sulfide adsorption layer 17 is not particularly limited, but is preferably 1 to 20 μm, and more preferably 2 to 5 μm. When the thickness of the hydrogen sulfide adsorption layer 17 is 1 μm or more, the hydrogen sulfide adsorption layer 17 can hold a sufficient amount of hydrogen sulfide adsorbent, and therefore hydrogen sulfide is more effectively adsorbed when it permeates the hydrogen sulfide adsorption layer 17. When the thickness of the hydrogen sulfide adsorption layer 17 is 20 μm or less, the total thickness of the packaging material 10 can be reduced.

[0045] <Base material layer> The base material layer 11 provides heat resistance in the sealing step when manufacturing the electricity storage device and plays a role in suppressing the occurrence of pinholes that may occur during molding, processing, and distribution. In particular, when the exterior material is an exterior material for a large-scale electricity storage device, the base material layer 11 can also be provided with scratch resistance, chemical resistance, insulating properties, and the like.

[0046] 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.

[0047] The substrate layer 11 may be in the form of a stretched or unstretched film, or in the form of a coating film. Furthermore, the substrate layer 11 may be a single layer or multiple layers, and in the case of multiple layers, different resins can be used in combination. If it is a film, it can be a co-extruded film or a film laminated with an adhesive. If the substrate layer 11 is a coating film, it can be a substrate layer 11 coated with the same number of layers. The substrate layer 11 can also be a multi-layered layer made by combining a film and a coating film.

[0048] Among these resins, polyester resin and polyamide resin 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, copolymers of nylon 6 and nylon 6,6, nylons such as nylon 10, nylon 11 and nylon 12, and aromatic polyamides such as nylon 9T and polymetaxylylene adipamide (MXD6).

[0049] When these resins are used in the form of a film, the base layer 11 is preferably a biaxially stretched film. When the base layer 11 is a biaxially stretched film, examples of the stretching method include sequential biaxial stretching, tubular biaxial stretching, and simultaneous biaxial stretching. The biaxially stretched film is preferably a film stretched by a tubular biaxial stretching method, from the viewpoint of obtaining better deep drawability.

[0050] The substrate layer 11 may or may not contain a hydrogen sulfide adsorbent, but preferably contains a hydrogen sulfide adsorbent. In this case, the hydrogen sulfide adsorbent is contained not only in the hydrogen sulfide adsorption layer 17 but also in the base material layer 11, so that when hydrogen sulfide permeates the packaging material 10, it is adsorbed not only by the hydrogen sulfide adsorbent in the hydrogen sulfide adsorption layer 17 but also by the hydrogen sulfide adsorbent in the base material layer 11. When the base material layer 11 is multilayered, one layer of the base material layer 11 may contain the hydrogen sulfide adsorbent, or multiple layers or all layers may contain the hydrogen sulfide adsorbent.

[0051] The content of the hydrogen sulfide adsorbent in the substrate layer 11 is not particularly limited, and may be less than 0.5 mass % or 0.5 mass % or more, but is preferably 0.5 mass % or more. In this case, hydrogen sulfide is effectively adsorbed by the hydrogen sulfide adsorbent in the substrate layer 11 . The content may be 1% by mass or more, or 2% by mass or more. The content may be 30% by mass or less, 20% by mass or less, 15% by mass or less, or 10% by mass or less. When the content is 30% by mass or less, the base layer 11 is less likely to become brittle.

[0052] The base layer 11 may contain a color developer that changes color upon reaction with hydrogen sulfide. The color developer is made of a metal salt of an acid. In this case, if the amount of hydrogen sulfide that permeates the packaging material 10 becomes excessive, the color developer in the base layer 11 begins to discolor due to a reaction with hydrogen sulfide. The discoloration of the color developer indicates that the hydrogen sulfide adsorbent can no longer adsorb hydrogen sulfide and that the packaging material 10 can no longer be used. This makes it easier to determine whether the packaging material 10 can be continued to be used. When both the hydrogen sulfide adsorption layer 17 and the substrate layer 11 contain a color developer, the color developers may be the same or different.

[0053] When the base layer 11 contains a color developer, the base layer 11 may or may not contain a hydrogen sulfide adsorbent. Here, the hydrogen sulfide adsorbent may be the same as the hydrogen sulfide adsorbent in the hydrogen sulfide adsorption layer 17. The hydrogen sulfide adsorbent in the base layer 11 may be the same as or different from the hydrogen sulfide adsorbent in the hydrogen sulfide adsorbent layer 17.

[0054] The content of the color developer in the base layer 11 may be 0.01% by mass or more, 0.1% by mass or more, 0.5% by mass or more, 1% by mass or more, or 2% by mass or more. When the content is 0.01% by mass or more, when the developer reacts with hydrogen sulfide and discolors, the discoloration of the base material layer 11 becomes more noticeable, making it easier to determine whether the exterior material 10 can be continued to be used. The content may be 30% by mass or less, 20% by mass or less, 5% by mass or less, or 1% by mass or less. When the content is 30% by mass or less, the base layer 11 is less likely to become brittle.

[0055] The total content of the hydrogen sulfide adsorbent and the color developer in the base layer 11 is preferably 30 mass % or less. In this case, the base layer 11 is less likely to become brittle. Furthermore, when the base layer 11 contains a resin, a decrease in the proportion of the resin further prevents the deterioration of the roles and functions that the resin originally has. The content may be 20% by mass or less, 15% by mass or less, or 10% by mass or less. The content may be 0.01% by mass or more, 0.5% by mass or more, 1% by mass or more, or 2% by mass or more.

[0056] The base layer 11 may further contain various additives, such as a flame retardant, a slip agent, an antiblocking agent, an antioxidant, a light stabilizer, a dehydrating agent, a crystal nucleating agent, and a tackifier, as needed.

[0057] The thickness of the base layer 11 is preferably 6 to 40 μm, and more preferably 10 to 30 μm. When the thickness of the base material layer 11 is 6 μm or more, it tends to be possible to improve the pinhole resistance and insulating properties of the packaging material 10. When the thickness of the base material layer 11 is 40 μm or less, it is possible to reduce the total thickness of the packaging material 10.

[0058] In order to suppress deformation of the base layer 11 during sealing, the melting point of the base layer 11 is preferably higher than the melting point of the sealant layer 16, and more preferably 30° C. or more higher than the melting point of the sealant layer 16.

[0059] <First adhesive layer> The first adhesive layer 12 is a layer that bonds the base material layer 11 and the metal foil layer 13 together. Specific examples of materials constituting the first adhesive layer 12 include polyurethane resins in which a bifunctional or higher isocyanate compound (a polyfunctional isocyanate compound) is allowed to react 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 exterior packaging material 10. In addition to the above, a material containing an epoxy resin as the main component and a hardener blended therein can also be used, but the material is not limited to this. Depending on the performance required for the first adhesive layer 12, various other additives and stabilizers may be blended into the above-mentioned materials.

[0060] The thickness of the first adhesive layer 12 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.

[0061] First adhesive layer 12 may or may not contain a hydrogen sulfide adsorbent. When first adhesive layer 12 contains a hydrogen sulfide adsorbent, the hydrogen sulfide adsorbent is contained not only in hydrogen sulfide adsorption layer 17 but also in first adhesive layer 12, and therefore, when hydrogen sulfide permeates packaging material 10, it is adsorbed not only by the hydrogen sulfide adsorbent in hydrogen sulfide adsorption layer 17 but also by the hydrogen sulfide adsorbent in first adhesive layer 12. Furthermore, because first adhesive layer 12 is located on the opposite side of sealant layer 16 with respect to metal foil layer 13, even if water is generated as a result of the adsorption reaction of hydrogen sulfide by the hydrogen sulfide adsorbent contained in first adhesive layer 12, the water does not easily permeate metal foil layer 13 and therefore does not easily penetrate into the bag formed using packaging material 10, thereby suppressing the generation of hydrogen sulfide.

[0062] The first adhesive layer 12 may or may not contain a color developer. When the first adhesive layer 12 contains a color developer, if there is a defect such as a pinhole in the metal foil layer 13, discoloration of the first adhesive layer 12 will be noticeable in the vicinity of the defect, making it easier to determine that the amount of hydrogen sulfide has become excessive and also to identify the defect in the metal foil layer 13. When the hydrogen sulfide adsorption layer 17, the base layer 11, and the first adhesive layer 12 all contain a color developer, the color developers may be the same or different from one another.

[0063] <Metal foil layer> The metal foil layer 13 has a water vapor barrier property that prevents moisture from permeating the packaging material 10. The metal foil layer 13 may also have extensibility so that it can be deep-drawn. Examples of metals that can be used to form the metal foil layer 13 include aluminum, stainless steel, copper, etc. From the standpoints of mass (specific gravity), moisture resistance, processability, and cost, the metal foil layer 13 is preferably aluminum foil.

[0064] As the aluminum foil, soft aluminum foil that has been subjected to annealing can be preferably used because it can impart the desired extensibility during molding. However, for the purpose of imparting further pinhole resistance and extensibility during molding, it is more preferable to use an aluminum foil containing iron. The content of iron in the aluminum foil is preferably 0.1 to 9.0 mass %, more preferably 0.5 to 2.0 mass %, based on 100 mass % of the aluminum foil. When the iron content is 0.1% by mass or more, it is possible to obtain an exterior packaging material 10 with better pinhole resistance and ductility. When the iron content is 9.0% by mass or less, it is possible to obtain an exterior packaging material 10 with better flexibility. As the aluminum foil, untreated aluminum foil may be used, but it is preferable to use aluminum foil that has been subjected to a degreasing treatment 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 of the foil.

[0065] The thickness of the metal foil 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.

[0066] <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 layer 13. The first corrosion prevention treatment layer 14a serves to increase the adhesion between the metal foil layer 13 and the first adhesive layer 12. The second corrosion prevention treatment layer 14b serves to increase the adhesion between the metal foil layer 13 and the second adhesive layer 15. The first corrosion prevention treatment layer 14a and the second corrosion prevention treatment layer 14b may be layers having the same configuration, or may be layers having 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 by, for example, degreasing treatment, hydrothermal treatment, anodizing treatment, chemical conversion treatment, or a combination of these treatments.

[0067] 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 singly 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, particularly when an aluminum foil is used for the metal foil layer 13, not only can the aluminum be degreased, but also a passive aluminum fluoride can be formed. Furthermore, acid degreasing agents are effective in terms of corrosion resistance. Alkaline degreasing may be achieved by using sodium hydroxide or the like.

[0068] 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 anodizing treatment is alumite treatment.

[0069] Examples of chemical conversion treatments include immersion-type chemical conversion treatments and coating-type chemical conversion treatments. Examples of immersion-type chemical conversion treatments 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 treatments. An example of the coating-type chemical conversion treatment is a method in which a coating agent having corrosion prevention properties is applied onto the metal foil layer 13.

[0070] When forming at least a part of the corrosion prevention treated layers 14a, 14b by any of the corrosion prevention treatments, hydrothermal treatment, anodizing treatment, and chemical conversion treatment, it is preferable to carry out the above-mentioned degreasing treatment beforehand. When a degreased metal foil, such as a metal foil that has been annealed, is used as the metal foil layer 13, there is no need to perform a degreasing process again when forming the corrosion prevention layers 14a and 14b.

[0071] 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.

[0072] Among the above treatments, hydrothermal conversion treatment and anodizing treatment, in particular, dissolve the aluminum foil surface with a treatment agent to form aluminum compounds (boehmite, alumite) with excellent corrosion resistance. Therefore, a bicontinuous structure is formed from the metal foil layer 13 using aluminum foil to the corrosion prevention treatment layers 14a, 14b, and the above 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 by a pure coating method alone, which is not included in the definition of chemical conversion treatment. One example of this method is to use 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 inhibitor effect and is also environmentally friendly. By using this method, it is possible to impart corrosion inhibitory effects to metal foils, such as aluminum foils, even with a general coating method.

[0073] Examples of the rare earth element oxide sol include sols using various solvents such as aqueous solvents, alcoholic solvents, hydrocarbon solvents, ketone solvents, ester solvents, ether solvents, etc. Among these, aqueous sols (sols using aqueous solvents) are preferred.

[0074] In order to stabilize the dispersion of the rare earth element oxide sol, inorganic acids such as nitric acid, hydrochloric acid, phosphoric acid, etc. or their salts, and organic acids such as acetic acid, malic acid, ascorbic acid, lactic acid, etc. are usually used as dispersion stabilizers. Among these dispersion stabilizers, phosphoric acid in particular is expected to have the following effects in the packaging material 10. (1) Dispersion stabilization of sol (2) Improved adhesion between the corrosion prevention treatment layers 14a, 14b and the metal foil layer 13 by utilizing the aluminum chelating ability of phosphoric acid (3) Imparting corrosion resistance by capturing aluminum ions (passivation) (4) Improvement of the cohesive strength of the corrosion prevention treatment layers (oxide layers) 14a and 14b due to the tendency of dehydration condensation of phosphoric acid to occur even at low temperatures.

[0075] 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.

[0076] 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 made by blending phosphoric acid and a chromium compound with a resin binder (such as aminophenol), as in the case of a known paint-type chromate. Use of this treatment agent allows for a layer that combines corrosion prevention functionality with good adhesion. Furthermore, although the stability of the coating liquid must be taken into consideration, a coating agent in which a rare earth element oxide sol and a polycationic polymer or a polyanionic polymer are preliminarily mixed into a one-component solution can be used to form a layer that combines corrosion prevention properties with good adhesion.

[0077] 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 corrosion prevention treatment layers 14a and 14b have a multi-layer structure or a single-layer structure. 2 is preferable, and 0.010 to 0.100 g / m 2 is more preferred. The mass per unit area is 0.005g / 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 metal foil layer 13. 2Even 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.

[0078] From the viewpoint of easily maintaining the adhesion between the sealant layer 16 and the metal foil 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 metal foil layer 13 to a chemical conversion treatment, or may be formed by subjecting the metal foil layer 13 to a chemical conversion treatment and contain a cationic polymer.

[0079] <Second adhesive layer> The second adhesive layer 15 is a layer that bonds the metal foil layer 13 and the sealant layer 16. The second adhesive layer 15 may be a layer obtained using an adhesive resin composition, or may be a layer obtained using an adhesive.

[0080] When the second adhesive layer 15 is a layer obtained using an adhesive resin composition, the adhesive resin composition is not particularly limited, but preferably contains a modified polyolefin resin.

[0081] 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.

[0082] 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.

[0083] 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 second adhesive layer 15.

[0084] When the second adhesive layer 15 is a layer obtained using an adhesive, a general adhesive for bonding the metal foil layer 13 and the sealant layer 16 can be used for the second adhesive layer 15.

[0085] When a corrosion prevention treatment layer 14b is provided on the metal foil 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 15 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.

[0086] For example, when the second corrosion prevention treatment layer 14b contains a cationic polymer, the second adhesive layer 15 contains a compound reactive with the cationic polymer. When the second corrosion prevention treatment layer 14b contains an anionic polymer, the second adhesive layer 15 contains a compound reactive with the anionic polymer. When the second corrosion prevention treatment layer 14b contains both a cationic polymer and an anionic polymer, the second adhesive layer 15 contains a compound reactive with the cationic polymer and a compound reactive with the anionic polymer. However, the second adhesive layer 15 does not necessarily need to contain both of these compounds; it may 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 15 may also contain an acid-modified polyolefin resin.

[0087] 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.

[0088] Among these, polyfunctional isocyanate compounds are preferred because they have high reactivity with cationic polymers and can easily form crosslinked structures.

[0089] The compound reactive with anionic polymers may be at least one compound selected from the group consisting of glycidyl compounds and compounds having an oxazoline group. Among these, glycidyl compounds are preferred because of their high reactivity with anionic polymers.

[0090] When the second adhesive layer 15 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.

[0091] The content of the reactive compound is preferably 1 to 10 times the equivalent of the acidic group in the acid-modified polyolefin resin. If the content of the reactive compound is 1 equivalent or more, 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 equivalents, the crosslinking reaction with the acid-modified polyolefin resin will be fully saturated, and there will be unreacted material, which may result in 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) relative to 100 parts by mass of the acid-modified polyolefin resin.

[0092] Acid-modified polyolefin resins are polyolefin resins into which acidic groups have been introduced. Examples of acidic groups include carboxyl groups, sulfonic acid groups, and acid anhydride groups, with maleic anhydride groups and (meth)acrylic acid groups being particularly preferred. As the acid-modified polyolefin resin, for example, the same modified polyolefin resin as that used in the sealant layer 16 can be used.

[0093] The second adhesive layer 15 may contain various additives, such as elastomers, flame retardants, slip agents, antiblocking agents, antioxidants, light stabilizers, and tackifiers, as needed.

[0094] The thickness of the second adhesive layer 15 is not particularly limited, but is preferably the same as or less than the thickness of the sealant layer 16 from the viewpoint of stress relaxation and moisture permeation.

[0095] <Sealant layer> The sealant layer 16 is a layer that provides sealing properties to the packaging material 10 by heat sealing, and is a layer that is placed on the inside and heat sealed (thermally fused) when assembling the electricity storage device. The sealant layer 16 may be either a single layer film or a multi-layer film.

[0096] The sealant layer 16 contains a resin. Examples of the resin include polyolefin-based resins and polyester-based resins. These resins may be used alone or in combination of two or more.

[0097] Examples of polyolefin resins include low-density, medium-density, or high-density polyethylene; ethylene-α-olefin copolymers; polypropylene; block or random copolymers containing propylene as a copolymerization component; and propylene-α-olefin copolymers.

[0098] Examples of polyester resins include polyethylene terephthalate (PET) resin, polybutylene terephthalate (PBT) resin, polyethylene naphthalate (PEN) resin, polybutylene naphthalate (PBN) resin, and copolymers thereof.

[0099] The sealant layer 16 may contain additives such as slip agents, antiblocking agents, antioxidants, light stabilizers, and flame retardants.

[0100] The sealant layer 16 may or may not contain a hydrogen sulfide adsorbent, but preferably does not contain a hydrogen sulfide adsorbent. In this case, gaps are not formed between the resin and the hydrogen sulfide adsorbent contained in the sealant layer 16 due to poor compatibility between them, improving the moisture barrier properties. In addition, because the sealant layer 16 does not contain a hydrogen sulfide adsorbent, which is a foreign substance to the resin, the heat seal strength can be increased.

[0101] The sealant layer 16 may or may not contain a color developer, but preferably does not contain a color developer. In this case, gaps are prevented from forming between the resin and the developer contained in the sealant layer 16 due to poor compatibility between them, improving the moisture barrier properties. In addition, because the sealant layer 16 does not contain a developer, which is a foreign substance to the resin, the heat seal strength can be increased.

[0102] The thickness of the sealant layer 16 is not particularly limited, but from the viewpoint of achieving both a thin film and improved heat seal strength in a high-temperature environment, it is preferably in the range of 5 to 100 μm, more preferably in the range of 10 to 100 μm, and even more preferably in the range of 20 to 80 μm. The total thickness of the second adhesive 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 85 μm, from the viewpoint of achieving both a thin film and improved heat seal strength in a high-temperature environment.

[0103] [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.

[0104] 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 metal foil layer 13, bonding the base material layer 11 and the metal foil layer 13 together using the first adhesive layer 12 to obtain a laminate, laminating a hydrogen sulfide adsorption layer 17 on the base material layer 11 of the laminate, further laminating a sealant layer 16 via a second adhesive layer 15 to produce a structure, and, if necessary, aging the obtained structure.

[0105] (Step of Laminating Anti-Corrosion Treatment Layers 14a and 14b on Metal Foil Layer 13) This step is a step of forming corrosion prevention treatment layers 14a and 14b on the metal foil layer 13. As described above, examples of the method include degreasing, hydrothermal treatment, anodizing, and chemical conversion treatment of the metal foil layer 13, and applying a coating agent having corrosion prevention properties.

[0106] Furthermore, when the corrosion prevention treatment layers 14a, 14b are multi-layered, the corrosion prevention treatment layers 14a, 14b can be formed, for example, by applying a coating liquid (coating agent) that constitutes the lower corrosion prevention treatment layer (metal foil layer 13 side) to the metal foil layer 13 and baking it to form a first layer, and then applying a coating liquid (coating agent) that constitutes the upper corrosion prevention treatment layer to the first layer and baking it to form a second layer, and repeating this process.

[0107] The degreasing treatment can be carried out by a spray method or an immersion method. The hydrothermal conversion treatment and anodizing treatment can be carried out by an immersion method. The chemical conversion treatment can be carried out by an immersion method, a spray method, a coating method, or the like, appropriately selected depending on the type of chemical conversion treatment.

[0108] The coating agent having corrosion prevention properties can be applied by various methods such as gravure coating, reverse coating, roll coating, and bar coating.

[0109] As described above, the various treatments may be performed on either one or both sides of the metal foil that constitutes the metal foil layer 13, but in the case of one-sided treatment, it is preferable that the treated surface be the side on which the sealant layer 16 is laminated. If desired, the surface of the base layer 11 may be subjected to the above treatment.

[0110] The amount of coating agent applied to form the first and second layers is 0.005 to 0.200 g / m 2 , or 0.010 to 0.100 g / m 2 may be.

[0111] Furthermore, when dry curing is required, the drying can be performed 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. Here, the base material temperature refers to the temperature of the metal foil layer 13.

[0112] (Step of bonding the base material layer 11 and the metal foil layer 13) This step is a step of bonding the metal foil layer 13 provided with the corrosion prevention treatment layers 14a and 14b to the base material layer 11 via the first adhesive layer 12 to obtain a laminate. Examples of the lamination method include methods such as dry lamination, non-solvent lamination, and wet lamination, in which the metal foil layer 13 and the base material layer 11 are laminated together using the material that constitutes the first adhesive layer 12 described above. The first adhesive layer 12 has a dry coating amount of 1 to 10 g / m 2 or 2 to 7 g / m 2 It may be set in the range.

[0113] (Laminating process of hydrogen sulfide adsorption layer) This step is a step of forming a hydrogen sulfide adsorption layer 17 on the surface of the substrate layer 11 of the laminate opposite to the metal foil layer 13. The hydrogen sulfide absorbing layer 17 may be a coating film or a film.

[0114] When the hydrogen sulfide-adsorbing layer 17 is a coating film, the hydrogen sulfide-adsorbing layer 17 can be formed by applying the above-mentioned resin composition (coating liquid) for forming a hydrogen sulfide-adsorbing layer to the substrate layer 11 and heating it. The resin composition for forming a hydrogen sulfide adsorption layer can be applied by various methods such as gravure coating, reverse coating, roll coating, and bar coating.

[0115] When dry curing is required, the drying can be carried out at a base material temperature in the range of 60 to 300° C. depending on the drying conditions of the resin composition for forming the hydrogen sulfide adsorption layer used.

[0116] When the hydrogen sulfide-adsorbing layer 17 is a film, the hydrogen sulfide-adsorbing layer 17 may be laminated by directly extruding a material obtained by dry-blending the components of the resin composition for forming the hydrogen sulfide-adsorbing layer using an extrusion laminator. Alternatively, the hydrogen sulfide-adsorbing layer 17 may be formed by forming a hydrogen sulfide-adsorbing layer as a cast film in advance using a resin composition for forming a hydrogen sulfide-adsorbing layer, and then laminating this hydrogen sulfide-adsorbing layer. The bonding method can be the same as the method used to bond the metal foil layer 13 and the base material layer 11 together. From the viewpoint of productivity, the formation speed (processing speed) of the hydrogen sulfide adsorption layer 17 can be, for example, 80 m / min or more. Before the hydrogen sulfide absorbing layer 17 is laminated on the laminate, the laminate may be aged.

[0117] (Laminating step of second adhesive layer 15 and sealant layer 16) This step is a step of forming a second adhesive layer 15 and a sealant layer 16 on the surface of the metal foil layer 13 on the side of the corrosion prevention treatment layer 14b to obtain a structure. The second adhesive layer 15 may be a layer obtained by using a heat-fusible resin composition, or may be a layer obtained by using an adhesive.

[0118] When the second adhesive layer 15 is a layer obtained using a heat-fusible resin composition, a method for laminating the second adhesive layer 15 and the sealant layer 16 includes a method of using an extrusion laminator to sandwich the second adhesive layer 15 with the corrosion prevention treatment layer 14b and the sealant layer 16. In this case, the sealant layer 16 may be formed in advance as a cast film using a resin composition for forming a sealant layer. Furthermore, lamination can also be performed by a tandem lamination method or a co-extrusion method in which the second adhesive layer 15 and the sealant layer 16 are extruded. In this case, the second adhesive layer 15 and the sealant layer 16 may be formed by extruding granules obtained by melt blending in advance 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. To form the second adhesive layer 15 and the sealant layer 16, a resin composition for forming the second adhesive layer containing the components of the second adhesive layer 15 described above and a resin composition for forming the sealant layer containing the components of the sealant layer 16 are used, respectively.

[0119] The second adhesive layer 15 may be laminated by directly extruding a material obtained by dry-blending the components of the resin composition for forming the second adhesive layer using an extrusion laminator.

[0120] The sealant layer 16 may be laminated by directly extruding a material obtained by dry-blending the components of the resin composition for forming the sealant layer using an extrusion laminator. From the viewpoint of productivity, the forming speed (processing speed) of the second adhesive layer 15 and the sealant layer 16 can be, for example, 80 m / min or more.

[0121] When the second adhesive layer 15 is a layer obtained using an adhesive, the second adhesive layer 15 and the sealant layer 16 can be laminated by bonding the sealant layer 16 to the second corrosion prevention treatment layer 14b side of the metal foil layer 13 via the second adhesive layer 15. Examples of the lamination method include wet lamination, dry lamination, etc. In this case, the sealant layer may be a cast film previously formed using the resin composition for forming a sealant layer.

[0122] When the sealant layer 16 is attached by dry lamination, a resin composition for forming the second adhesive layer 15 is applied onto the second corrosion prevention treatment layer 14b, and the solvent is removed and the layer is dried at a predetermined temperature, after which the sealant layer 16 is laminated. The preferred dry application amount of the resin composition for forming the second adhesive layer is the same as that of the resin composition for forming the first adhesive layer 12 .

[0123] The lamination process of the second adhesive layer 15 and the sealant layer 16 results in a structure as shown in FIG. 1, in which the hydrogen sulfide adsorption layer 17, the substrate layer 11, the first adhesive layer 12, the first corrosion prevention treatment layer 14a, the metal foil layer 13, the second corrosion prevention treatment layer 14b, the second adhesive layer 15, and the sealant layer 16 are laminated in this order.

[0124] (Aging treatment process) This step is a step of aging (curing) the structure. By aging the structure, it is possible to promote adhesion between the substrate layer 11, the first adhesive layer 12, the first corrosion prevention treatment layer 14a, and the metal foil layer 13, as well as adhesion between the metal foil layer 13, the second corrosion prevention treatment layer 14b, the second adhesive layer 15, and the sealant layer 16.

[0125] In this manner, the packaging material 10 of this embodiment as shown in FIG. 1 can be manufactured.

[0126] [Electricity storage device] Next, a power storage device according to an embodiment of the present disclosure will be described with reference to Fig. 2. Fig. 2 is a perspective view of the power storage device according to an embodiment of the present disclosure. 2, the electricity storage device 50 includes an electricity storage element 52 and an outer bag 54 that houses the electricity storage element 52. The outer bag 54 is obtained using the outer packaging material 10. The electricity storage device 50 may further include two metal terminals (current extraction terminals) 53 extending from the electricity storage element 52 and for extracting current to the outside. Here, the metal terminals 53 are sandwiched by the exterior packaging material 10. A tab sealant may be interposed between the metal terminals 53 and the exterior packaging material 10. The outer bag 54 usually houses the electricity storage element 52 in an airtight state, but does not necessarily have to house the electricity storage element 52 in an airtight state.

[0127] The electricity storage element 52 has a positive electrode, an electrolyte, and a negative electrode in this order.

[0128] In the exterior packaging material 10, the hydrogen sulfide adsorption layer 17 is the outermost layer, and the sealant layer 16 is the innermost layer. The exterior bag 54 may be formed by folding one exterior packaging material 10 in half and heat-sealing the peripheral edges so that the hydrogen sulfide adsorption layer 17 is the outermost layer and the sealant layer 16 is the innermost layer (see FIG. 2), or by stacking two exterior packaging materials 10 with the sealant layers 16 facing each other and heat-sealing the peripheral edges.

[0129] According to the electricity storage device 50, even if hydrogen sulfide is generated inside the outer bag 54, the hydrogen sulfide can be effectively adsorbed by the hydrogen sulfide adsorbent in the hydrogen sulfide adsorption layer 17 as the hydrogen sulfide permeates through the outer bag 54. Therefore, the electricity storage device 50 can prevent the hydrogen sulfide generated inside the outer bag 54 from leaking out of the outer bag 54. Furthermore, because the hydrogen sulfide adsorption layer 17 is located on the opposite side of the metal foil layer 13 from the sealant layer 16, even if water is generated as a result of the adsorption reaction of hydrogen sulfide by the hydrogen sulfide adsorbent, the water does not easily permeate the metal foil layer 13 and therefore does not easily enter the outer bag 54. This prevents the electrolyte in the electricity storage element 52 housed inside the outer bag 54 from coming into contact with water, thereby preventing the generation of hydrogen sulfide due to the reaction between water and the electrolyte.

[0130] The electrolyte may be a liquid electrolyte or a solid electrolyte, and examples of the solid electrolyte include oxide-based solid electrolytes and sulfide-based solid electrolytes.

[0131] Metal terminal 53 is a part of the current collector taken out of packaging material 10, and is made of metal foil such as copper foil or aluminum foil.

[0132] Specific examples of the power storage device 50 include secondary batteries such as all-solid-state batteries, lithium-ion batteries, nickel-metal hydride batteries, and lead-acid batteries, as well as electrochemical capacitors such as electric double layer capacitors, and semi-solid batteries. The present disclosure is particularly useful when the power storage device 50 is an all-solid-state battery. When the power storage device 50 is an all-solid-state battery, that is, when the power storage element 52 is a power storage element having a solid electrolyte, hydrogen sulfide may be generated when the power storage element 52 comes into contact with moisture. Even in this case, however, the hydrogen sulfide is effectively adsorbed by the hydrogen sulfide adsorbent in the hydrogen sulfide adsorption layer 17 as it permeates the outer bag 54, and leakage of hydrogen sulfide to the outside of the outer bag 54 can be suppressed.

[0133] [Electricity storage equipment] Next, an electric power storage device according to an embodiment of the present disclosure will be described with reference to Fig. 3. Fig. 3 is a cross-sectional view schematically showing an electric power storage device according to an embodiment of the present disclosure. 3, the power storage device 60 includes a plurality of power storage devices 50 and a housing 65 that houses the plurality of power storage devices 50. A space exists between the housing 65 and the plurality of power storage devices 50. The power storage device 60 may further include two or more metal terminals for extracting current generated in the plurality of power storage devices 50 to the outside of the power storage device 60. The plurality of power storage devices 50 may be connected in series or in parallel.

[0134] According to the electrical storage device 60, even when hydrogen sulfide is generated in each electrical storage device 50, when the hydrogen sulfide permeates through the outer packaging bag 54, the hydrogen sulfide adsorbent in the hydrogen sulfide adsorption layer 17 can effectively adsorb the hydrogen sulfide. Therefore, this electrical storage device 60 can suppress the leakage of hydrogen sulfide generated in each electrical storage device 50 into the space between the electrical storage device 50 and the housing 65. Further, in the electrical storage device 50, since the hydrogen sulfide adsorption layer 17 is located on the side opposite to the sealant layer 16 with respect to the base material layer 11, even if hydrogen sulfide leaks from the outer packaging bag 54 of a certain electrical storage device 50 into the space between the electrical storage device 50 and the housing 65 due to a defect in any one of the electrical storage devices 50, the hydrogen sulfide adsorption layer 17 of the outer packaging bag 54 of the other electrical storage devices 50 can effectively adsorb the hydrogen sulfide, and the leakage of hydrogen sulfide to the outside of the housing 65 can be suppressed. The material constituting the housing 65 is not particularly limited, and for example, it is constituted of metal, resin, or the like.

Example

[0135] Hereinafter, the present disclosure will be specifically described based on examples, but the present disclosure is not limited to the following examples.

[0136] [Materials used] The materials used in the examples and comparative examples are shown below. <Base agent for forming the outermost layer> As the base agent for forming the outermost layer, a polyurethane-based coating agent obtained by adding a curing agent (product name: SP curing agent, manufactured by Toyo Ink Co., Ltd.) composed of an adduct of hexamethylene diisocyanate (HDI) and toluene as a solvent to 100 parts by mass of a polyester polyol-based main agent (product name: Bayron 200, manufactured by Toyobo Co., Ltd.) was used. Note that the "outermost layer" becomes the "hydrogen sulfide adsorption layer" when it contains a hydrogen sulfide (hereinafter, also referred to as "H2S") adsorbent.

[0137] <H2S adsorbent and color developer> Zinc oxide was used as the H2S adsorbent, and lead acetate was used as the color developer.

[0138] <Base material layer> As the base layer, the following base layer films A1, A2, B, C, and D were used. (Base layer film A1) Easy-to-form polyethylene terephthalate film (easy-to-form PET, thickness 25 μm, manufactured by Unitika Ltd., double-sided corona treatment) (Base layer film A2) Easy-to-form polyethylene terephthalate film (easy-to-form PET, thickness 25 μm, manufactured by Unitika Ltd., one-sided corona treatment) (Base layer film B) A film obtained by extruding a dry blend of polyethylene terephthalate (PET) pellets, an H2S adsorbent, and a color developer into a film using the extrusion lamination method, and then corona treating both sides of the resulting single-layer PET film. The amounts of the H2S adsorbent and the color developer to be dry-blended were each 3 mass % based on the total mass of the obtained base layer film. The thickness of the base layer film B was 25 μm. (Base layer film C) A film obtained in the same manner as base layer film B except that no developer was added. (Base layer film D) A film obtained in the same manner as in base layer film C, except that the content of the H2S adsorbent was 0.01 mass% based on the total mass of the obtained base layer film.

[0139] <Materials for forming the first corrosion prevention treatment layer (base layer side) and the second corrosion prevention treatment layer (sealant layer side)> The following (CL-1) and (CL-2) were used as materials for forming the first corrosion prevention treatment layer (substrate layer side) and the second corrosion prevention treatment layer (sealant layer side). (CL-1): "Sodium polyphosphate-stabilized cerium oxide sol" obtained by using distilled water as a solvent and adjusting the solid content to 10% by mass. The sodium polyphosphate stabilized cerium oxide sol was obtained by blending 10 parts by mass of sodium salt of phosphoric acid with 100 parts by mass of cerium oxide. (CL-2): A composition consisting of 90% by mass of "polyallylamine (manufactured by Nitto Boseki Co., Ltd.)" and 10% by mass of "polyglycerol polyglycidyl ether (manufactured by Nagase ChemteX Corporation)" obtained by adjusting the solid content concentration to 5% by mass using distilled water as a solvent.

[0140] <Metal foil layer (thickness 40 μm)> Annealed and degreased soft aluminum foil (manufactured by Toyo Aluminum Co., Ltd., product name "8079 material") was used.

[0141] <Adhesive for forming adhesive layer> The adhesive used for forming the adhesive layer was a polyurethane adhesive obtained by adding 15 parts by mass of a curing agent containing toluene diisocyanate (TDI) (product name: CAT10, manufactured by Toyo Morton Co., Ltd.) to 100 parts by mass of a polyester polyol-based base agent (product name: AD502, manufactured by Toyo Morton Co., Ltd.).

[0142] <Resin for forming second adhesive layer> The resin used for forming the second adhesive layer was acid-modified polypropylene (acid-modified PP), which was "Modic (registered trademark) P555" manufactured by Mitsubishi Chemical Corporation.

[0143] <Resin for forming sealant layer> Polypropylene (PP) was used as the resin for forming the sealant layer. PC684S manufactured by SunAllomer Co., Ltd. was used as the polypropylene.

[0144] [Fabrication of exterior materials] Example 1 First, first and second corrosion prevention treatment layers were provided on both sides of the metal foil layer by the following procedure. That is, the material (CL-1) was applied to both surfaces of the metal foil layer in a dry coating amount of 70 mg / m 2 The layers were coated by microgravure coating so that the thickness was 20 mg / m², and then baked in a drying unit at 200°C. After that, (CL-2) was applied to the layers formed with the material (CL-1) on both sides in a dry coating amount of 20 mg / m². 2In this way, first and second corrosion prevention treatment layers were formed on both sides of the metal foil layer.

[0145] Next, the substrate layer film A1 was attached to the first corrosion prevention treatment layer using an adhesive for forming an adhesive layer by dry lamination. That is, the adhesive for forming an adhesive layer was applied to the surface of the metal foil layer facing the first corrosion prevention treatment layer so that the thickness after curing was 5 μm, and the adhesive was heated and dried at 80 ° C for 1 minute, and then laminated to the substrate layer and aged at 80 ° C for 120 hours. In this way, a laminate (substrate layer / adhesive layer / first corrosion prevention treatment layer / metal foil layer / second corrosion prevention treatment layer) was obtained.

[0146] Next, an H2S adsorption layer, which is the outermost layer, was formed on the substrate layer of the laminate obtained as described above by the following procedure. First, a hydrogen sulfide adsorbent was added to a base agent for forming the outermost layer to obtain a composition for forming the outermost layer (coating liquid). The composition for forming the outermost layer was then applied to the substrate layer of the laminate using a bar coater and dried at 100°C for 1 minute to form an H2S adsorption layer. The amount of adsorbent added to the base agent for forming the outermost layer was such that the content of the H2S adsorbent would be 3 mass% based on the total mass of the H2S adsorption layer after drying. The amount of the composition for forming the outermost layer was such that the thickness of the H2S adsorption layer after drying would be 3 μm.

[0147] Finally, a second adhesive layer and a sealant layer were laminated in this order on the second corrosion prevention treatment layer. That is, the laminate was set on the unwinding section of an extrusion laminator. Then, the second adhesive layer resin and the sealant layer resin were co-extruded from a T-die under processing conditions of 270 ° C and 80 m / min, thereby laminating the second adhesive layer and the sealant layer in this order on the second corrosion prevention treatment layer. In addition, the thickness ratio of the second adhesive layer and the sealant layer was set to 2:1, and the total thickness was 80 μm.

[0148] In this way, the packaging material for a power storage device according to Example 1 (H2S adsorption layer / adhesive layer / first corrosion prevention treatment layer / metal foil layer / second corrosion prevention treatment layer / second adhesive layer / sealant layer) was obtained.

[0149] (Examples 2 and 4 to 6) Except for preparing a composition for forming an outermost layer by mixing an H2S adsorbent and a color developer with a base agent for forming an outermost layer, the packaging materials of Examples 2 and 4 to 6 were obtained in the same manner as in Example 1. The contents of the H2S adsorbent and color developer added to the base agent for forming an outermost layer were adjusted so that the contents of the H2S adsorbent and color developer based on the total mass of the H2S adsorption layer after drying were the values ​​shown in Table 1.

[0150] Example 3 An exterior packaging material of Example 3 was obtained in the same manner as in Example 2, except that the film B for base layer was used as the base layer instead of the film A1 for base layer.

[0151] (Comparative Example 1) An exterior packaging material of Comparative Example 1 was obtained in the same manner as in Example 1, except that no H2S adsorbent was added to the base agent for forming the outermost layer.

[0152] (Comparative Example 2) An exterior material of Comparative Example 2 was obtained in the same manner as in Example 1, except that the base material layer film A2 was used instead of the base material layer film A1 as the base material layer, the corona-treated surface of the base material layer film A2 was laminated on the metal foil layer side, and no H2S adsorption layer was formed.

[0153] (Comparative Example 3) An exterior material of Comparative Example 3 was obtained in the same manner as in Example 1, except that a color developer was added to the base agent for forming the outermost layer without adding an H2S adsorbent, to prepare a composition for forming the outermost layer. The amount of color developer added to the base agent for forming the outermost layer was set so that the content would be 3 mass% based on the total mass of the H2S adsorption layer after drying.

[0154] Comparative Example 4 An exterior packaging material of Comparative Example 4 was obtained in the same manner as in Comparative Example 2, except that the film C for base layer was used as the base layer instead of the film A2 for base layer.

[0155] (Comparative Example 5) An exterior packaging material of Comparative Example 5 was obtained in the same manner as in Comparative Example 2, except that the film D for base layer was used as the base layer instead of the film A2 for base layer.

[0156] [Evaluation of H2S adsorption] The H2S adsorption capacity of the packaging materials of the Examples and Comparative Examples was evaluated by the following procedure. First, a sheet measuring 50 mm x 50 mm was cut out from each of the packaging materials according to the Examples and Comparative Examples, and the sheet was attached to the inside of a 2 L Tedlar bag so that the inner wall of the Tedlar bag was in contact with the sealant layer of the packaging material. At this time, the four sides of the sheet were sealed with polyimide tape to prevent H2S from entering the gap between the sheet and the Tedlar bag. Next, the Tedlar bag was sealed, and air and H2S were injected into the bag so that the H2S concentration in the bag was 20 ppm. The Tedlar bag was then sealed again and allowed to stand at room temperature for 168 hours (1 week). The H2S concentration in the Tedlar bag was then measured using a detector tube gas measuring instrument and evaluated based on the following criteria. The results are shown in Table 1. The unit of H2S concentration, "ppm," stands for "ppm by mass." (Evaluation criteria) 〇 (Pass): H2S concentration is 9 ppm or less × (Fail): H2S concentration exceeds 9 ppm

[0157] [Table 1]

[0158] The results shown in Table 1 show that the packaging materials of Examples 1 to 6 had sufficiently low H2S concentrations in the Tedlar bags after standing for 168 hours compared to the packaging materials of Comparative Examples 1 to 5. From the above, it was confirmed that the packaging materials of the present disclosure can effectively adsorb hydrogen sulfide.

[0159] The outline of this disclosure is as follows. [1] An exterior packaging material for an electricity storage device, comprising a hydrogen sulfide adsorption layer containing a hydrogen sulfide adsorbent, a substrate layer, a metal foil layer, and a sealant layer in this order, the hydrogen sulfide adsorbent is made of a metal oxide, The packaging material for a power storage device, wherein the content of the hydrogen sulfide adsorbent in the hydrogen sulfide adsorption layer is 0.5 mass % or more. [2] The packaging material for a power storage device according to [1], wherein the base layer contains a hydrogen sulfide adsorbent, and the hydrogen sulfide adsorbent is made of a metal oxide. [3] The packaging material for a power storage device according to [1] or [2], wherein the content of the hydrogen sulfide adsorbent in the base material layer is 0.5 mass % or more. [4] The packaging material for a storage battery device according to any one of [1] to [3], wherein at least one of the hydrogen sulfide adsorption layer and the base material layer further contains a color developer that changes color upon reaction with hydrogen sulfide, and the color developer is made of a metal salt of an acid. [5] The packaging material for a power storage device according to [4], wherein the total content of the hydrogen sulfide adsorbent and the color developer in the hydrogen sulfide adsorption layer or the base material layer is 30 mass % or less. [6] The packaging material for a power storage device according to any one of [1] to [5], wherein the metal oxide includes an oxide of a divalent metal. [7] The packaging material for a power storage device according to any one of [1] to [6], wherein the hydrogen sulfide adsorption layer is obtained using a coating liquid containing the hydrogen sulfide adsorbent. [8] The packaging material for a power storage device according to [7], wherein the coating liquid further contains a binder resin, and the binder resin contains at least one of an acrylic resin and a urethane resin. [9] The packaging material for a power storage device according to any one of [1] to [8], wherein the sealant layer contains a resin but does not contain a hydrogen sulfide adsorbent.

[10] The packaging material for a power storage device according to any one of [1] to [9], further comprising an adhesive layer between the base material layer and the metal foil layer.

[11] An outer bag; an electricity storage element housed in the outer bag, The outer packaging bag is obtained using the outer packaging material for a power storage device according to any one of [1] to

[10] , The electricity storage device, wherein the hydrogen sulfide adsorption layer of the packaging material for the electricity storage device is an outermost layer, and the electricity storage element contains an electrolyte.

[12] The electricity storage device according to

[11] , wherein the electrolyte is a solid electrolyte.

[13] A plurality of power storage devices; a housing that houses the plurality of power storage devices, The power storage device is the power storage device according to

[11] or

[12] . [Industrial Applicability]

[0160] INDUSTRIAL APPLICABILITY The exterior packaging material for an electricity storage device according to the present disclosure can effectively adsorb hydrogen sulfide and is therefore useful as an exterior packaging material for an electricity storage device such as an all-solid-state battery. [Explanation of symbols]

[0161] 10...outer packaging material for electricity storage device, 11...substrate layer, 13...metal foil layer, 15...second adhesive layer (adhesive layer), 16...sealant layer, 17...hydrogen sulfide adsorption layer, 50...electricity storage device, 60...electricity storage equipment, 65...casing

Claims

1. An outer casing material for an electricity storage device, comprising, in this order, a hydrogen sulfide adsorption layer containing a hydrogen sulfide adsorbent, a substrate layer, a metal foil layer, and a sealant layer, the hydrogen sulfide adsorbent is made of a metal oxide; the hydrogen sulfide adsorbent content in the hydrogen sulfide adsorption layer is 0.5 mass % or more.

2. 2 . The packaging material for a power storage device according to claim 1 , wherein the base layer contains a hydrogen sulfide adsorbent, and the hydrogen sulfide adsorbent is made of a metal oxide.

3. The packaging material for a power storage device according to claim 2 , wherein the content of the hydrogen sulfide adsorbent in the base material layer is 0.5 mass % or more.

4. 2. The exterior packaging material for a power storage device according to claim 1, wherein at least one of the hydrogen sulfide adsorption layer and the base layer further contains a color developer that changes color upon reaction with hydrogen sulfide, the color developer comprising a metal salt of an acid.

5. 5. The packaging material for a power storage device according to claim 4, wherein a total content of the hydrogen sulfide adsorbent and the color developer in the hydrogen sulfide adsorption layer or the base material layer is 30 mass % or less.

6. The packaging material for a power storage device according to claim 1 , wherein the metal oxide comprises an oxide of a divalent metal.

7. The packaging material for a power storage device according to claim 1 , wherein the hydrogen sulfide adsorption layer is obtained using a coating liquid containing the hydrogen sulfide adsorbent.

8. The packaging material for a power storage device according to claim 7 , wherein the coating liquid further contains a binder resin, and the binder resin contains at least one of an acrylic resin and a urethane resin.

9. The packaging material for a power storage device according to claim 1 , wherein the sealant layer contains a resin and does not contain a hydrogen sulfide adsorbent.

10. The packaging material for a power storage device according to claim 1 , further comprising an adhesive layer between the base material layer and the metal foil layer.

11. An outer bag, a storage element accommodated in the outer bag, The outer packaging bag is obtained using the outer packaging material for a power storage device according to any one of claims 1 to 10, the hydrogen sulfide adsorption layer of the electrical storage device packaging material is an outermost layer, The power storage device, wherein the power storage element includes an electrolyte.

12. The power storage device according to claim 11 , wherein the electrolyte is a solid electrolyte.

13. A plurality of power storage devices; a housing that houses the plurality of power storage devices, The power storage device is the power storage device according to claim 11.

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