Exterior materials for energy storage devices

Abstract

To provide an exterior material for a power storage device which is excellent in heat resistance and has sufficient deep drawing moldability.SOLUTION: An exterior material for a power storage device has such a laminated structure as to have a base material layer, a first adhesive layer, a metallic foil layer, a second adhesive layer and a sealant layer in this order, in which the first adhesive layer and the second adhesive layer contain an urethane-based compound that is a reactant of a polyol-based resin and a polyisocyanate compound, in the first adhesive layer and the second adhesive layer, an infrared absorption spectrum peak intensity at 2,250 to 2,290 cm-1 is represented by A, and an infrared absorption spectrum peak intensity at 1,680 to 1,720 cm-1 is represented by B, X defined by the following expression (1) is 10 to 90, and glass transition temperatures of the first adhesive layer and the second adhesive layer are 60-80°C. Expression (1): X={B / (A+B)}×100.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an exterior material for an electricity storage device. [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. Multilayer films, which are lightweight, have high heat dissipation properties, and can be produced at low cost, are increasingly being used as exterior materials for lithium-ion batteries.

[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 an electricity storage device called an all-solid-state battery as a next-generation battery 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 laminate-type all-solid-state battery is manufactured using the above-mentioned laminate as an exterior material, delamination may occur between layers of the exterior material (particularly between the substrate layer or sealant layer and the barrier layer) due to insufficient heat resistance of the exterior material, which may result in insufficient sealing of the package of the all-solid-state battery.

[0007] Furthermore, in such all-solid-state batteries, the deeper the recesses formed by cold forming, the more battery contents can be accommodated, thereby increasing the energy density. Therefore, the exterior material made of a multilayer film is required to have sufficient deep-draw formability to form recesses of the desired depth.

[0008] The present invention has been made in view of the above-mentioned problems, and has an object to provide an exterior packaging material that has excellent heat resistance and sufficient deep drawability. [Means for solving the problem]

[0009] In order to achieve the above object, the present invention provides a laminated structure having a base layer, a first adhesive layer, a metal foil layer, a second adhesive layer, and a sealant layer in this order, wherein the first adhesive layer and the second adhesive layer contain a urethane-based compound which is a reaction product of a polyol-based resin and a polyisocyanate compound, and ... -1 The infrared absorption spectrum peak intensity is A, 1680-1720 cm -1When the infrared absorption spectrum peak intensity of the above is taken as B, X defined in the following formula (1) is 10 to 90, and the glass transition temperatures of the first adhesive layer and the second adhesive layer are 60 to 80°C. X = {B / (A+B)} × 100 … (1)

[0010] The packaging material for an electricity storage device has excellent heat resistance and sufficient deep drawability. The inventors consider the reason why such effects are achieved as follows.

[0011] That is, the urethane group of the urethane compound has a very high cohesive strength. Also, since the urethane group has active hydrogen in the molecule, hydrogen bonds are generated between the interface of the bonded object and the active hydrogen, thereby improving the adhesive strength of the interface. Furthermore, in the adhesive layer, the 1680 to 1720 cm -1 The infrared absorption spectrum peak intensity of 2250-2290 cm originating from the isocyanate group of the raw material -1 When X, which is determined using the infrared absorption spectrum peak intensity of the compound, is 10 or more, the urethane group of the urethane compound exhibits high cohesive force, and when X is 90 or less, excessive curing of the adhesive layer is suppressed, and the adhesive layer has high adhesion.

[0012] Furthermore, when X defined in the above general formula (1) is 10 to 90 and the glass transition temperature is 60 to 80°C, the adhesive layer has a sufficient crosslinking density and has strength that allows the adhesive layer to withstand the shear stress applied when stretched by deep drawing. Furthermore, when X defined in the above general formula (1) and the glass transition temperature are within the above ranges, the adhesive layer does not become excessively rigid, and when stretched by deep drawing, it follows the stretching of the base layer and metal foil layer, etc., and the occurrence of microfractures in the adhesive layer can be suppressed.

[0013] As a result, the packaging material in which both the first adhesive layer and the second adhesive layer contain a urethane compound, X is 10 to 90, and the glass transition temperature is 60 to 80°C has excellent heat resistance and sufficient deep drawability.

[0014] In the present invention, the polyol-based resin may be a polyester polyol-based resin. Compared with other polyol-based resins, polyester polyol-based resins tend to have a large number of esters derived from dicarboxylic acids (polar groups) in the molecule, resulting in high hydrogen bonding strength, which improves adhesion between the adhesive layer and the substrate layer, sealant layer, and metal foil layer. As a result, the resulting packaging material has even better deep-draw formability.

[0015] The present invention can further include a corrosion prevention treatment layer between at least the second adhesive layer and the metal foil layer, thereby providing the resulting packaging material with even better deep drawability and heat resistance, which makes it less susceptible to delamination between the packaging material layers (particularly between the substrate layer or sealant layer and the metal foil layer) even under high temperature conditions (e.g., 100 to 150°C).

[0016] In the present invention, the sealant layer may contain at least one of a polyolefin resin and a polyester resin, or may contain a polyester resin. When the sealant layer contains a polyolefin resin with a high melting point, the resulting packaging material has excellent heat resistance, and when the sealant layer contains a polyester resin with a higher melting point, the resulting packaging material has even more excellent heat resistance.

[0017] In the present invention, the polyisocyanate compound may contain an aromatic polyisocyanate compound or an adduct of an aromatic polyisocyanate compound. When the polyisocyanate compound contains such a compound, intermolecular π-π stacking between aromatic rings or π-H interactions occur, improving the cohesive strength of the adhesive layer. Therefore, when the polyisocyanate compound contains an aromatic polyisocyanate compound or an adduct thereof, the resulting packaging material has excellent heat resistance. Furthermore, since the adduct of the aromatic polyisocyanate compound has active hydrogen in its molecule, hydrogen bonding occurs between the interface of the bonded object and the active hydrogen, thereby improving the adhesion strength at the interface. As a result, the resulting packaging material has even better heat resistance.

[0018] In the present invention, at least the second adhesive layer may contain a hydrogen sulfide adsorbing substance, thereby making the resulting packaging material less susceptible to delamination between the metal foil layer and the sealant layer even when hydrogen sulfide is generated from the electricity storage device, and thus having excellent hydrogen sulfide resistance.

[0019] The packaging material of the present invention may be used for an all-solid-state battery. The packaging material of the present invention has excellent heat resistance and sufficient deep-draw formability, and is therefore suitable for use in an all-solid-state battery in which a recess is formed by cold forming and the battery contents are housed in the recess. [Effects of the Invention]

[0020] According to the present invention, it is possible to provide an exterior packaging material for an electricity storage device that has excellent heat resistance and sufficient deep drawability. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a schematic cross-sectional view of an exterior packaging material for an electricity storage device according to one embodiment of the present invention. [Figure 2]1A and 1B are diagrams showing an embossed type exterior material obtained using an exterior material for an electricity storage device according to one embodiment of the present invention, in which (a) is a perspective view thereof, and (b) is a longitudinal cross-sectional view taken along line bb of the embossed type exterior material shown in (a). [Figure 3] 1A and 1B are perspective views showing the process of manufacturing a secondary battery using an exterior material for an electricity storage device according to one embodiment of the present invention, in which (a) shows the state in which the exterior material for an electricity storage device has been prepared, (b) shows the state in which the embossed exterior material for an electricity storage device and a battery element have been prepared, (c) shows the state in which a part of the exterior material for an electricity storage device has been folded back and the end portion has been melted, and (d) shows the state in which both sides of the folded back part have been folded back upward. DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference numerals, and redundant explanations will be omitted.

[0023] [Exterior materials for energy storage devices] FIG. 1 is a cross-sectional view schematically illustrating one embodiment of the electrical storage device packaging material of the present invention. As shown in FIG. 1, packaging material (electrical storage device packaging material) 10 of this embodiment is a laminate comprising a substrate layer 11, a first adhesive layer 12 provided on one side of the substrate layer 11, a metal foil layer 13 provided on the side of the first adhesive layer 12 opposite the substrate layer 11 and having corrosion prevention treatment layers 14a and 14b on both sides, a second adhesive layer 15 provided on the side of the metal foil layer 13 opposite the first adhesive layer 12, and a sealant layer 16 provided on the side of the second adhesive layer 15 opposite the metal foil layer 13. Here, corrosion prevention treatment layer 14a is provided on the side of the metal foil layer 13 facing the first adhesive layer 12, and corrosion prevention treatment layer 14b is provided on the side of the metal foil layer 13 facing the second adhesive layer 15. In packaging material 10, substrate layer 11 is the outermost layer, and 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. Each layer will be described below.

[0024] <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, processing, 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, insulating properties, etc.

[0025] The base layer 11 preferably has a peak melting temperature higher than that of the sealant layer 16. By having the base layer 11 have a peak melting temperature higher than that of the sealant layer 16, it is possible to prevent the appearance from deteriorating due to melting of the base layer 11 (outer layer) during heat sealing. When the sealant layer 16 has a multilayer structure, the peak melting temperature of the sealant layer 16 refers to the peak melting temperature of the layer with the highest peak melting temperature. The peak melting temperature of the base layer 11 is preferably 290°C or higher, more preferably 290 to 350°C. Examples of resin films that can be used as the base layer 11 and have a peak melting temperature within the above range include nylon film, PET film, polyamide film, polyphenylene sulfide film (PPS film), polyimide film, and polyester film. The peak melting temperature refers to a value determined in accordance with the method described in JIS K7121-1987.

[0026] A commercially available film may be used as the substrate layer 11, or the substrate layer 11 may be formed by coating (application of a coating liquid and drying). The substrate layer 11 may have a single-layer structure or a multi-layer structure, and may be formed by applying a thermosetting resin. The substrate layer 11 may also contain various additives (e.g., flame retardants, slip agents, antiblocking agents, antioxidants, light stabilizers, tackifiers, etc.).

[0027] Melting peak temperature T of the base layer 11 11 and the melting peak temperature T of the sealant layer 16 16 The difference (T 11 -T 16is preferably 20° C. or more. When this temperature difference is 20° C. or more, deterioration of the appearance of the packaging material 20 due to heat sealing can be more sufficiently suppressed. The thickness of the base material layer 11 is preferably 5 to 50 μm, and more preferably 12 to 30 μm.

[0028] <First adhesive layer 12 and second adhesive layer 15> The first adhesive layer 12 and the second adhesive layer 15 will be described in detail below.

[0029] (First adhesive layer 12) The first adhesive layer 12 is a layer that bonds the metal foil layer 13, on which the corrosion prevention treatment layer 14a is provided, to the base material layer 11. The first adhesive layer 12 has the adhesive strength required to firmly bond the base material layer 11 and the metal foil layer 13, and also has conformability to prevent the metal foil layer 13 from being broken by the base material layer 11 during cold forming. Note that conformability refers to the property of the first adhesive layer 12 remaining on the member without peeling off, even if the member is deformed due to expansion and contraction or the like.

[0030] Examples of adhesive components that form the first adhesive layer 12 include urethane compounds and polyolefin resins. The adhesive components may be used alone or in combination of two or more. The urethane compounds are obtained by reacting a polyol resin as a base resin with a polyisocyanate compound as a curing agent.

[0031] Examples of polyol-based resins include polyester polyol-based resins, polyether polyol-based resins, and acrylic polyol-based resins. The polyol-based resin is preferably a polyester polyol-based resin, because it improves the adhesion between the adhesive layer and the sealant layer and the metal foil layer, and the resulting packaging material has even better deep-draw formability.

[0032] Examples of polyester polyol-based resins include those obtained by reacting one or more dicarboxylic acids with a diol.

[0033] Examples of polyether polyol resins include those produced by addition polymerization of ethylene oxide or propylene oxide with propylene glycol, glycerin, pentaerythritol, or the like.

[0034] Examples of acrylic polyol-based resins include copolymers obtained by copolymerizing at least a hydroxyl group-containing acrylic monomer with (meth)acrylic acid. In this case, it is preferable that the copolymer contains a structural unit derived from (meth)acrylic acid as the main component. Examples of hydroxyl group-containing acrylic monomers include 2-hydroxyethyl (meth)acrylate and 2-hydroxypropyl (meth)acrylate.

[0035] 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.

[0036] The polyolefin resin may have an acidic group introduced therein to improve adhesion to the base layer 11 and the metal foil layer 13. Examples of the acidic group to be introduced include a carboxy group and a sulfonic acid group, with the carboxy group being particularly preferred.

[0037] Examples of acid-modified polyolefin resins in which carboxy groups have been introduced into polyolefin resins include acid-modified polyolefin resins obtained by graft-modifying a polyolefin resin with an unsaturated carboxylic acid or its acid anhydride, or an ester of an unsaturated carboxylic acid or its acid anhydride in the presence of a radical initiator.

[0038] 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.

[0039] Examples of the acid anhydrides of unsaturated carboxylic acids include maleic anhydride, itaconic anhydride, citraconic anhydride, tetrahydrophthalic anhydride, and bicyclo[2,2,1]hept-2-ene-5,6-dicarboxylic anhydride.

[0040] Examples of the ester of an unsaturated carboxylic acid or an acid anhydride thereof include 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.

[0041] The proportion of the graft compound in the acid-modified polyolefin resin is preferably 0.2 to 100 parts by mass relative to 100 parts by mass of the polyolefin resin.

[0042] The polyisocyanate compound contains multiple isocyanate groups and serves to crosslink the polyol-based resin. One type of polyisocyanate compound may be used alone, or two or more types may be used in combination. Examples of the polyisocyanate compound include aliphatic polyisocyanate compounds, alicyclic polyisocyanate compounds, and aromatic polyisocyanate compounds. Aromatic polyisocyanate compounds are preferred because they improve the heat resistance of the resulting exterior material.

[0043] Examples of aliphatic polyisocyanate compounds include hexamethylene diisocyanate (HDI) and xylylene diisocyanate (XDI). Examples of alicyclic polyisocyanate compounds include isophorone diisocyanate (IPDI). Examples of aromatic polyisocyanate compounds include tolylene diisocyanate (TDI) and diphenylmethane diisocyanate (MDI). As the polyisocyanate compound, multimers (e.g., trimers) of these compounds can also be used, and specifically, adducts, biurets, isocyanurates, etc. can be used. The polyisocyanate compound is preferably an adduct, as this improves the adhesion strength at the interface between the adhesive layer and the object to be adhered and improves the heat resistance of the resulting exterior material.

[0044] In the urethane compound, the molar ratio of the isocyanate groups of the polyisocyanate compound to the hydroxyl groups of the polyol resin is preferably 1-50, more preferably 10-30.

[0045] A catalyst may be used to control the reaction between the polyol resin as the base resin and the polyisocyanate compound as the curing agent. The polyisocyanate compound may hydrolyze upon reaction with moisture contained in the composition containing the base resin and the curing agent or in the atmosphere, producing an amine compound. The amine compound may then react with the polyisocyanate compound, resulting in self-condensation. However, the use of a catalyst can suppress the progression of these side reactions. As a result, the proportion of urethane groups in the urethane compound in the first adhesive layer can be increased. Examples of such catalysts include organotin compounds such as dibutyltin compounds and dioctyltin compounds, organotitanium compounds, and organozirconium compounds.

[0046] The first adhesive layer 12 preferably contains a hydrogen sulfide adsorbent, since this can inhibit corrosion of the metal foil layer 13 by hydrogen sulfide present outside the packaging material. Examples of such hydrogen sulfide adsorbents include zinc oxide and potassium permanganate. When the first adhesive layer 12 contains a hydrogen sulfide adsorbent, the content thereof is preferably 1 to 50 mass % relative to the total amount of the first adhesive layer 12, since this can inhibit corrosion of the metal foil layer 13 by hydrogen sulfide present outside the packaging material.

[0047] The thickness of the first adhesive layer 12 is preferably 1 to 10 μm, more preferably 2 to 6 μm, from the viewpoint of obtaining the desired adhesive strength, conformability, processability, and the like.

[0048] The first adhesive layer 12 can be obtained, for example, by applying a composition containing the main adhesive agent and curing agent described above. Any known application method can be used, including gravure direct, gravure reverse (direct, kiss), and microgravure.

[0049] When the first adhesive layer 12 contains a urethane-based compound, the content of the polyol-based resin in the composition containing the polyol-based resin and the polyisocyanate compound is preferably 50 to 90 mass% relative to the total amount of the polyol-based resin and the polyisocyanate compound.

[0050] When the first adhesive layer 12 contains a urethane-based compound and a catalyst is used during the reaction between the polyol-based resin and the polyisocyanate compound, the content of the catalyst in the composition containing the polyol-based resin, the polyisocyanate compound, and the catalyst is preferably 0.1 to 20 mass% relative to the total amount of the polyisocyanate compound.

[0051] When the first adhesive layer 12 contains an epoxy resin, it is preferable that the content of the polymer having two or more epoxy groups in the molecule in a composition containing a polymer having two or more epoxy groups in the molecule and a compound having a functional group that reacts with the epoxy groups is 30 to 60 mass% relative to the total amount of these compounds.

[0052] (Second adhesive layer 15) The second adhesive layer 15 is a layer that bonds the metal foil layer 13 provided with the corrosion prevention treatment layer 14b to the sealant layer 16.

[0053] Examples of adhesive components that form the second adhesive layer 15 include the same adhesive components as those listed for the first adhesive layer 12.

[0054] The second adhesive layer 15 preferably contains a hydrogen sulfide adsorbent, since this can inhibit corrosion of the metal foil layer 13 by hydrogen sulfide generated from the battery contents inside the exterior packaging. Examples of such hydrogen sulfide adsorbents include the same hydrogen sulfide adsorbents as those listed for the first adhesive layer 12. The content of the hydrogen sulfide adsorbent can also be set to the same range as the content of the hydrogen sulfide adsorbent in the first adhesive layer 12.

[0055] The second adhesive layer 15 is obtained by the same method as the first adhesive layer 12. When the second adhesive layer 15 contains a urethane-based compound, the content ratio of the polyol-based resin in the composition containing the polyol-based resin and the polyisocyanate compound may be the same as that of the first adhesive layer 12. When a catalyst is used in the reaction between the polyol-based resin and the polyisocyanate compound in forming the second adhesive layer 15, the content ratio of the catalyst in the composition containing the polyol-based resin, the polyisocyanate compound, and the catalyst may be the same as that of the first adhesive layer 12.

[0056] The thickness of the second adhesive layer 15 is preferably 1 to 5 μm. When the thickness of the second adhesive layer 15 is 1 μm or more, sufficient adhesive strength between the metal foil layer 13 and the sealant layer 16 is easily obtained, and when the thickness is 5 μm or less, the occurrence of cracks in the second adhesive layer 15 can be suppressed.

[0057] The first adhesive layer 12 and the second adhesive layer 15 contain a urethane-based compound which is a reaction product of a polyol-based resin and a polyisocyanate compound, and have a viscosity of 2250 to 2290 cm -1 The infrared absorption spectrum peak intensity is A, 1680-1720 cm -1When the infrared absorption spectrum peak intensity is B, X defined by the following formula (1) is 10 to 90, preferably 15 to 75, and more preferably 20 to 60. X = {B / (A+B)} × 100 … (1)

[0058] 2250 to 2290 cm in the first adhesive layer 12 and the second adhesive layer 15 -1 Infrared absorption spectrum peak intensity and 1680-1720cm -1 The infrared absorption spectrum peak intensity can be measured by FT-IR (ATR method (attenuated total reflection infrared spectroscopy)).

[0059] The glass transition temperatures of the first adhesive layer and the second adhesive layer are 60 to 80° C., and since the resulting packaging material has even better deep drawability, the temperature is preferably 60 to 75° C., and more preferably 65 to 70° C. The glass transition temperature of the adhesive layer means a value determined using a rigid pendulum-type physical property tester.

[0060] <Metal foil layer 13> Examples of the metal foil layer 13 include various metal foils such as aluminum and stainless steel, and from the standpoint of moisture resistance, processability such as ductility, and cost, aluminum foil is preferred for the metal foil layer 13. The aluminum foil may be a general soft aluminum foil, but is preferably an iron-containing aluminum foil from the standpoint of excellent pinhole resistance and ductility during molding.

[0061] In the aluminum foil containing iron (100% by mass), the iron content is preferably 0.1 to 9.0% by mass, and more preferably 0.5 to 2.0% by mass (for example, aluminum foil made of JIS 8021 material or 8079 material). When the iron content is 0.1% by mass or more, an exterior packaging material 10 having better pinhole resistance and ductility can be obtained. When the iron content is 9.0% by mass or less, an exterior packaging material 10 having better flexibility can be obtained.

[0062] Furthermore, as the aluminum foil, soft aluminum foil that has been annealed is more preferable because it can impart desired extensibility during molding.

[0063] The metal foil used for the metal foil layer 13 is preferably subjected to, for example, a degreasing treatment in order to obtain the desired electrolyte resistance. Furthermore, in order to simplify the manufacturing process, it is preferable that the surface of the metal foil is not etched. For example, a wet-type degreasing treatment or a dry-type degreasing treatment can be used as the degreasing treatment, but a dry-type degreasing treatment is preferred from the viewpoint of simplifying the manufacturing process.

[0064] An example of the dry-type degreasing treatment is a method in which the degreasing treatment is performed by extending the treatment time during the annealing treatment of the metal foil. Sufficient electrolyte resistance can be obtained even with the degreasing treatment performed simultaneously with the annealing treatment performed to soften the metal foil.

[0065] The dry-type degreasing treatment may be a treatment other than the annealing treatment, such as flame treatment or corona treatment. Furthermore, the dry-type degreasing treatment may be, for example, a degreasing treatment in which contaminants are oxidatively decomposed and removed by active oxygen generated when a metal foil is irradiated with ultraviolet light of a specific wavelength.

[0066] The wet-type degreasing treatment may be, for example, an acid degreasing treatment, an alkaline degreasing treatment, or the like. The acid used in the acid degreasing treatment may be, for example, an inorganic acid such as sulfuric acid, nitric acid, hydrochloric acid, or hydrofluoric acid. These acids may be used alone or in combination of two or more. The alkali used in the alkaline degreasing treatment may be, for example, sodium hydroxide, which has a high etching effect. The alkaline degreasing treatment may also be performed using a weak alkaline material or a material containing a surfactant or the like. The wet-type degreasing treatment described above may be performed by, for example, a dipping method or a spray method.

[0067] From the viewpoints of barrier properties, pinhole resistance, and processability, the thickness of the metal foil layer 13 is preferably 9 to 200 μm, more preferably 15 to 150 μm, and even more preferably 15 to 100 μm. When the thickness of the metal foil layer 13 is 9 μm or more, the metal foil layer 13 is less likely to break even when stress is applied during molding. When the thickness of the metal foil layer 13 is 200 μm or less, the increase in mass of the exterior material can be reduced, and a decrease in the weight energy density of the electricity storage device can be suppressed.

[0068] <Corrosion prevention treatment layers 14a, 14b> The corrosion prevention treatment layers 14a and 14b serve to suppress corrosion of the metal foil layer 13 due to the electrolytic solution or a corrosive liquid or gas, such as hydrofluoric acid, generated by the reaction of the electrolytic solution with water. The corrosion prevention treatment layer 14a also serves to increase the adhesion between the metal foil layer 13 and the first adhesive layer 12. The corrosion prevention treatment layer 14b also serves to increase the adhesion between the metal foil layer 13 and the second adhesive layer 15. The corrosion prevention treatment layers 14a and 14b may be layers of the same configuration or layers of different configurations.

[0069] The corrosion prevention treatment layers 14a, 14b can be formed, for example, by carrying out a degreasing treatment, a hydrothermal treatment, an anodizing treatment, a chemical conversion treatment, a coating-type corrosion prevention treatment in which a coating agent having corrosion prevention properties is applied to the layer that serves as the base material of the corrosion prevention treatment layers 14a, 14b, or a corrosion prevention treatment that combines these treatments.

[0070] Among the above-mentioned treatments, degreasing, hydrothermal modification, and anodizing, particularly hydrothermal modification and anodizing, are treatments that dissolve the surface of the metal foil (aluminum foil) using a treatment agent to form a metal compound (aluminum compound (boehmite, alumite)) that has excellent corrosion resistance. For this reason, such treatments are sometimes included in the definition of chemical conversion treatment, since they obtain a structure that forms a co-continuous structure from the metal foil layer 13 to the corrosion prevention treatment layers 14a, 14b.

[0071] 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. For acid degreasing, an acid degreasing agent obtained by dissolving a fluorine-containing compound such as monosodium ammonium difluoride in the inorganic acid can be used. This not only degreases the metal foil layer 13, but also forms a passive metal fluoride, which is effective in terms of hydrofluoric acid resistance. Examples of alkaline degreasing include a method using sodium hydroxide or the like.

[0072] The hydrothermal modification treatment may be, for example, a boehmite treatment, which is obtained by immersing the metal foil layer 13 in boiling water containing triethanolamine. The anodizing treatment may be, for example, an anodizing treatment. The chemical conversion treatment may be, for example, a chromate treatment, a zirconium treatment, a titanium treatment, a vanadium treatment, a molybdenum treatment, a calcium phosphate treatment, a strontium hydroxide treatment, a cerium treatment, a ruthenium treatment, or a combination of two or more of these. It is preferable to perform the above-mentioned degreasing treatment before these hydrothermal modification treatments, anodizing treatments, and chemical conversion treatments.

[0073] The chemical conversion treatment is not limited to a wet method, and may be, for example, a method in which the treating agent used in the treatment is mixed with a resin component and then applied. Furthermore, the corrosion prevention treatment is preferably a coating-type chromate treatment, from the viewpoint of maximizing its effect and of waste liquid treatment.

[0074] Examples of coating agents used in coating-type corrosion prevention treatments include coating agents containing at least one selected from the group consisting of rare earth element oxide sol, anionic polymers, and cationic polymers. In particular, methods using coating agents containing rare earth element oxide sol are preferred.

[0075] The mass per unit area of ​​the corrosion prevention treatment layers 14a and 14b is 0.005 to 0.200 g / m 2The range is preferably 0.010 to 0.100 g / m 2 More preferably, the range 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 metal foil layer 13. 2 Above this value, the corrosion prevention function saturates and no further effect can be expected. Note that although the above information is given in terms of mass per unit area, it is also possible to convert the thickness from this if the specific gravity is known.

[0076] The thickness of the corrosion prevention layers 14a and 14b is preferably, for example, 10 nm to 5 μm, and more preferably 20 to 500 nm, from the viewpoint of corrosion prevention function and anchor function.

[0077] <Sealant layer 16> 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.

[0078] Examples of the sealant layer 16 include a film made of an acrylic resin, a polyolefin resin, or a polyester resin. The sealant layer 16 is preferably a film made of a polyolefin resin or a polyester resin, and more preferably a film made of a polyester resin, because these have a high melting point and further improve the heat resistance of the resulting exterior material.

[0079] Examples of acrylic resins include polymethyl methacrylate resin (PMMA), etc. These acrylic resins may be used alone or in combination of two or more.

[0080] Examples of polyolefin resins include low-density, medium-density, and high-density polyethylene, ethylene-α-olefin copolymers, polypropylene, and propylene-α-olefin copolymers. When the polyolefin resin is a copolymer, it may be a block copolymer or a random copolymer.

[0081] Examples of polyester resins include polyethylene terephthalate (PET) and polybutylene terephthalate (PBT), etc. These polyester resins may be used alone or in combination of two or more.

[0082] 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 together by coextrusion or by dry lamination.

[0083] The sealant layer 16 may also contain various additives such as flame retardants, slip agents, antiblocking agents, antioxidants, light stabilizers, and tackifiers.

[0084] The thickness of the sealant layer 16 is preferably 10 to 100 μm, and more preferably 20 to 60 μm. When the thickness of the sealant layer 16 is 10 μm or more, sufficient heat seal strength can be obtained, and when the thickness is 100 μm or less, the amount of water vapor penetrating from the edge of the packaging material can be reduced.

[0085] The peak melting temperature of the sealant layer 16 is preferably 200 to 280° C., as this improves heat resistance.

[0086] [Exterior material manufacturing method] Next, a description will be given of a method for manufacturing the packaging material 10. Note that the method for manufacturing the packaging material 10 is not limited to the following method.

[0087] An example of a method for producing the packaging material 10 is a method in which the following steps S11 to S13 are carried out in this order. Step S11: A step of forming a corrosion prevention treatment layer 14a on one surface of the metal foil layer 13 and forming a corrosion prevention treatment layer 14b on the other surface of the metal foil layer 13. Step S12: A step of bonding the surface of the corrosion prevention treatment layer 14a opposite to the metal foil layer 13 to the base material layer 11 via the first adhesive layer 12. Step S13: A step of forming a sealant layer 16 on the surface of the corrosion prevention treatment layer 14b opposite to the metal foil layer 13, with a second adhesive layer 15 interposed therebetween.

[0088] <Process S11> In step S11, a corrosion prevention treatment layer 14a is formed on one surface of the metal foil layer 13, and a corrosion prevention treatment layer 14b is formed on the other surface of the metal foil layer 13. The corrosion prevention treatment layers 14a and 14b may be formed separately, or both may be formed at the same time. Specifically, for example, a corrosion prevention treatment agent (base material of the corrosion prevention treatment layer) is applied to both surfaces of the metal foil layer 13, followed by drying, curing, and baking, to form the corrosion prevention treatment layers 14a and 14b at the same time. Alternatively, a corrosion prevention treatment agent may be applied to one surface of the metal foil layer 13, followed by drying, curing, and baking, to form the corrosion prevention treatment layer 14a, and then the corrosion prevention treatment layer 14b may be formed on the other surface of the metal foil layer 13 in the same manner. The order in which the corrosion prevention treatment layers 14a and 14b are formed is not particularly limited. The corrosion prevention treatment agents used for the corrosion prevention treatment layers 14a and 14b may be different or the same. The method for applying the corrosion prevention treatment agent is not particularly limited, but for example, methods such as gravure coating, gravure reverse coating, roll coating, reverse roll coating, die coating, bar coating, kiss coating, comma coating, and small diameter gravure coating can be used.

[0089] <Process S12> In step S12, the surface of the corrosion prevention treatment layer 14a opposite to the metal foil layer 13 and the base material layer 11 are bonded together by a method such as dry lamination using an adhesive to form the first adhesive layer 12. In step S12, a heat treatment may be performed to promote the adhesiveness of the first adhesive layer 12. The temperature during the heat treatment is not particularly limited, but may be, for example, 40 to 120°C.

[0090] <Process S13> After step S12, the surface of corrosion prevention treatment layer 14b opposite to metal foil layer 13 of the laminate in which base layer 11, first adhesive layer 12, corrosion prevention treatment layer 14a, metal foil layer 13, and corrosion prevention treatment layer 14b are laminated in this order is bonded to sealant layer 16 by a technique such as dry lamination using an adhesive to form second adhesive layer 15. In step S13, heat treatment may be performed to promote the adhesion of second adhesive layer 15. The temperature during heat treatment is not particularly limited, but may be, for example, 40 to 120°C.

[0091] The packaging material 10 is obtained through the above-described steps S11 to S13. The order of steps in the method for producing the packaging material 10 is not limited to a method in which the above-described steps S11 to S13 are performed sequentially. For example, the order of the steps may be changed as appropriate, such as performing step S12 before performing step S11.

[0092] [Energy storage devices] Next, an electricity storage device including a packaging material 10 as a container will be described. The electricity storage device includes a battery element 1 including electrodes, leads 2 extending from the electrodes, and a container that houses the battery element 1. The container is formed from the packaging material 10 for an electricity storage device so that the sealant layer 16 faces the inside. The container may be obtained by overlapping two packaging materials with the sealant layers 16 facing each other and heat-sealing the peripheral edges of the overlapped packaging materials 10, or by folding one packaging material over itself and similarly heat-sealing the peripheral edges of the packaging material 10. The lead 2 is sandwiched and sealed by the packaging material 10 that forms the container with the sealant layer 16 facing the inside. The lead 2 may be sandwiched by the packaging material 10 via a tab sealant.

[0093] The packaging material of this embodiment can be used in various power storage devices. Examples of such power storage devices include secondary batteries such as lithium-ion batteries, nickel-metal hydride batteries, lead-acid batteries, and all-solid-state batteries, as well as electrochemical capacitors such as electric double layer capacitors. The packaging material 10 of this embodiment has excellent deep-draw formability, making it suitable for use in all-solid-state batteries, in which recesses are formed by cold forming and the battery contents are housed in the recesses.

[0094] [Method of manufacturing an electricity storage device] Next, a method for manufacturing an electricity storage device using the above-mentioned exterior material 10 will be described. Here, an example will be described in which a secondary battery 40 is manufactured using an embossed-type exterior material 30. FIG. 2 is a diagram showing the above-mentioned embossed-type exterior material 30. (a) to (d) of FIG. 3 are perspective views showing the manufacturing process of a one-sided molded battery using the exterior material 10. The secondary battery 40 may be a double-sided molded battery manufactured by preparing two exterior materials such as the embossed-type exterior material 30 and bonding them together while adjusting their alignment.

[0095] The secondary battery 40, which is a one-sided molded battery, can be manufactured, for example, by the following steps S21 to S26. Step S21: A step of preparing a packaging material 10, a battery element 1 including electrodes, and leads 2 extending from the electrodes. Step S22: A step of forming a recess 32 for arranging the battery element 1 on one side of the packaging material 10 to obtain an embossed type packaging material 30 (see FIGS. 3(a) and 3(b)). Step S23: A step of placing the battery element 1 in the molding processing area (recess 32) of the embossed type exterior material 30, folding the embossed type exterior material 30 over so that the lid portion 34 covers the recess 32, and heat-sealing one side of the embossed type exterior material 30 so as to sandwich the lead 2 extending from the battery element 1 (see Figures 3(b) and 3(c)). Step S24: A step in which one side other than the side that clamps the lead 2 is left and the other sides are heat-sealed, and then an electrolyte is injected from the remaining side and the remaining side is heat-sealed in a vacuum state (see Figure 3(c)). Step S25: A step of causing a chemical change (formation) by charging and discharging under predetermined conditions such as current value, voltage value, and ambient temperature. Step S26: A step of cutting the ends of the heat-sealed sides other than the sides that hold the leads 2 and bending them toward the molding processing area (recess 32) side (see FIG. 3(d)).

[0096] <Process S21> In step S21, a packaging material 10, a battery element 1 including electrodes, and leads 2 extending from the electrodes are prepared. The packaging material 10 is prepared based on the above-described embodiment. There are no particular limitations on the battery element 1 and the leads 2, and known battery elements 1 and leads 2 can be used.

[0097] <Process S22> In step S22, a recess 32 for disposing the battery element 1 is formed on the sealant layer 16 side of the packaging material 10. The planar shape of the recess 32 matches the shape of the battery element 1, for example, a rectangular shape in plan view. The recess 32 is formed, for example, by pressing a pressing member having a rectangular pressure surface against a part of the packaging material 10 in its thickness direction. The pressing position, i.e., the recess 32, is formed at a position shifted toward one end of the packaging material 10 in the longitudinal direction from the center of the rectangular cut-out packaging material 10. As a result, after molding, the other end side where the recess 32 is not formed can be folded back to form a lid (lid portion 34).

[0098] More specifically, a molding process (deep drawing) using a mold can be used as a method for forming the recesses 32. One molding method involves using a female mold and a male mold arranged so that there is a gap equal to or greater than the thickness of the packaging material 10, and pressing the male mold together with the packaging material 10 into the female mold. The depth of the recesses 32 (amount of deep drawing) can be adjusted to a desired amount by adjusting the amount of pressing of the male mold. An embossed-type packaging material 30 is obtained by forming the recesses 32 in the packaging material 10. This embossed-type packaging material 30 has a shape such as that shown in FIG. 2. Here, FIG. 2(a) is a perspective view of the embossed-type packaging material 30, and FIG. 2(b) is a longitudinal cross-sectional view taken along line bb of the embossed-type packaging material 30 shown in FIG. 2(a).

[0099] <Process S23> In step S23, a battery element 1 composed of a positive electrode, a separator, a negative electrode, etc. is placed in a molding area (recess 32) of the embossed-type exterior material 30. Furthermore, the leads 2 extending from the battery element 1 and joined to the positive electrode and the negative electrode, respectively, are pulled out of the molding area (recess 32). The embossed-type exterior material 30 is then folded back approximately at the center in the longitudinal direction, overlapped with the sealant layers 16 facing inward, and one side of the embossed-type exterior material 30 that sandwiches the lead 2 is heat-sealed. The heat-sealing is controlled by three conditions: temperature, pressure, and time, and is set appropriately. The heat-sealing temperature is preferably equal to or higher than the temperature at which the sealant layer 16 melts, and specifically, can be 180°C or higher.

[0100] After heat sealing, a curing step is performed in which the entire sealant layer 16 is heated. This promotes crystallization in areas other than the heat-sealed portion, ensuring heat resistance throughout the packaging material 10. The curing step can be performed at a temperature of 80 to 150°C.

[0101] The thickness of sealant layer 16 before heat sealing is preferably 40% to 80% of the thickness of lead 2. When the thickness of sealant layer 16 is equal to or greater than the above-mentioned lower limit, the resin constituting sealant layer 16 tends to be able to sufficiently fill the ends of lead 2, and when the thickness is equal to or less than the above-mentioned upper limit, the thickness of the ends of packaging material 10 of secondary battery 40 can be kept appropriately small, and the amount of moisture penetrating from the ends of packaging material 10 can be reduced.

[0102] <Process S24> In step S24, the remaining sides are heat-sealed, leaving only one side other than the side that holds the lead 2. Then, electrolyte is injected from the remaining side, and the remaining side is heat-sealed in a vacuum state. The heat-sealing conditions are the same as in step S23.

[0103] <Process S25> In step S25, the secondary battery 40 obtained up to step S23 is charged and discharged to cause a chemical change (formation: 3 days in a 40°C environment). Then, the secondary battery 40 is opened once to remove gas generated by the formation and to replenish the electrolyte, and then a final seal is performed. Note that this step S25 can be omitted.

[0104] <Process S26> The ends of the heat-sealed sides other than the sides that hold the leads 2 are cut, and the sealant layer 16 that protrudes from the ends is removed. Thereafter, the heat-sealed parts are folded back toward the molding processing area 32 to form folded back parts 42, thereby obtaining the secondary battery 40.

[0105] Although the preferred embodiments of the packaging material for an electricity storage device of the present invention have been described in detail above, the present invention is not limited to these embodiments and various modifications and changes are possible. [Example]

[0106] The present invention will be described in more detail below based on examples, but the present invention is not limited to the following examples. [Materials used] The materials used in the examples and comparative examples are shown below.

[0107] <Base layer (thickness 25 μm)> A polyethylene terephthalate film, one side of which had been corona treated, was used.

[0108] <First adhesive layer (thickness 4 μm) and second adhesive layer (thickness 3 μm)> An adhesive was used in which the base agent, curing agent, catalyst, and hydrogen sulfide adsorbent shown in Table 1 were blended in the proportions shown in Table 2. Details of the base agent and curing agent shown in Tables 1 and 2 are as follows. The catalyst and hydrogen sulfide adsorbent used were the following compounds. {Main ingredient} Acrylic polyol resin (manufactured by Toei Kasei Co., Ltd., product name: YS#6158) Polyester polyol resin (manufactured by Unitika Ltd., product name: Elitel UE-3220) Polyolefin resin (Mitsui Chemicals, Inc., product name: Unistole P501) {hardening agent} HDI-B (hexamethylene diisocyanate-biuret, manufactured by Asahi Kasei Corporation, product name: Duranate 24A-100) HDI-A (hexamethylene diisocyanate-adduct, manufactured by Toyo Ink Co., Ltd., product name: SP hardener) TDI-A (Toluene diisocyanate adduct, manufactured by Toyo Ink Co., Ltd., product name: CAT-10L) TDI-N (Toluene diisocyanate-nurate, manufactured by Mitsui Chemicals, Inc., product name: Takenate D-204EA-1) {catalyst} Organotitanium compound (manufactured by Matsumoto Fine Chemical Co., Ltd., trade name: Orgatics TC-401) {Hydrogen sulfide adsorbent} Zinc oxide (manufactured by Ishihara Sangyo Kaisha, Ltd., product name: FZO-50)

[0109] <Corrosion prevention treatment layer> Distilled water was used as the solvent, and the sodium polyphosphate-stabilized cerium oxide sol was prepared with a solids concentration of 10% by mass. The sodium polyphosphate-stabilized cerium oxide sol was prepared by blending 100 parts by mass of cerium oxide with 10 parts by mass of sodium phosphate.

[0110] <Metal foil layer (thickness 35 μm)> Annealed and degreased soft aluminum foil (manufactured by Toyo Aluminum Co., Ltd., "8079 material") was used.

[0111] <Sealant layer (thickness 40 μm)> As the sealant layer, the films shown in Table 1 were prepared.

[0112] [Exterior material manufacturing] <Examples 1 to 5 and Comparative Examples 1 to 3> The metal foil layer was attached to the base layer using an adhesive (first adhesive layer) by dry lamination, and then the sealant layer was attached to the surface of the metal foil layer opposite to the surface to which the first adhesive layer was attached using an adhesive (second adhesive layer) by dry lamination.

[0113] The laminate thus obtained was heat-treated under the conditions shown in Table 2 to produce an exterior material (substrate layer / first adhesive layer / metal foil layer / second adhesive layer / sealant layer).

[0114] <Examples 6 to 11> First, a sodium polyphosphate-stabilized cerium oxide sol was applied to both sides of the metal foil layer by gravure coating. Next, the applied sodium polyphosphate-stabilized cerium oxide sol was dried, and then a baking treatment was carried out sequentially to form corrosion prevention treatment layers on both sides of the metal foil layer. The baking conditions were a temperature of 150°C and a treatment time of 30 seconds.

[0115] Next, one side of the metal foil layer on which the corrosion prevention treatment layer was formed was attached to a base layer using an adhesive (first adhesive layer) by dry lamination, and then a sealant layer was attached to the other side of the metal foil layer on which the corrosion prevention treatment layer was formed by dry lamination using an adhesive (second adhesive layer).

[0116] The laminate thus obtained was heat-treated under the conditions shown in Table 2 to produce an exterior material (substrate layer / first adhesive layer / corrosion prevention treatment layer / metal foil layer / corrosion prevention treatment layer / second adhesive layer / sealant layer).

[0117] [Measurement of urethane content] <First adhesive layer> The metal foil layer and the substrate layer that were in close contact with the first adhesive layer were peeled off to expose the first adhesive layer. The infrared absorption spectrum peak intensity of the exposed first adhesive layer was measured by infrared spectroscopy (IR). -1 The infrared absorption spectrum peak intensity is A, 1680-1720 cm -1 When the peak intensity of the infrared absorption spectrum of the compound was designated as B, the urethane abundance ratio (X) was calculated using the following formula (2). The results are shown in Table 1. Urethane abundance ratio (X) = {B / (A+B)} × 100 … (2)

[0118] <Second adhesive layer> The metal foil layer and sealant layer in contact with the second adhesive layer were peeled off to expose the second adhesive layer. The urethane content of the exposed second adhesive layer was calculated in the same manner as for the first adhesive layer. The results are shown in Table 1.

[0119] [Measurement of glass transition temperature Tg] <First adhesive layer and second adhesive layer> The glass transition temperatures Tg of the first adhesive layer and the second adhesive layer were determined by differential scanning calorimetry (DSC) measurement at a measurement temperature of 20 to 300° C. and a heating rate of 10° C. / min. The results are shown in Table 1.

[0120] [Evaluation of heat-resistant laminate strength on sealant layer side] <Measurement method> The packaging material was cut to a width of 15 mm, and the laminate strength between the metal foil layer of the packaging material and the sealant layer was measured under any one of the following conditions 1 to 3. Peeling was performed at a 90° angle, and the peeling speed was 50 mm / min. Condition 1: The exterior packaging material was heated at 80°C for 5 minutes, and then the laminate strength was measured while being heated at 80°C. Condition 2: The exterior packaging material was heated at 150°C for 5 minutes, and then the laminate strength was measured while heating at 150°C. Condition 3: The exterior packaging material was heated at 100° C. and exposed to hydrogen sulfide at a concentration of 20 ppm for one week, and then the laminate strength was measured using the same method as in Condition 2 above.

[0121] <Evaluation criteria> The laminate strength was evaluated based on the following criteria, and the results are shown in Table 3. ◎: Laminate strength is 2.5N / 15mm or more ○: Laminate strength is 2.0N / 15mm or more and less than 2.5N / 15mm △: Laminate strength is 1.5N / 15mm or more and less than 2.0N / 15mm ×: Laminate strength is less than 1.5N / 15mm

[0122] [Deep draw formability] <Measurement method> The molding depth at which deep drawing was possible for the exterior packaging materials obtained in each example was evaluated using the following method. The molding depth of the molding machine was set to 1.0 to 5.0 mm in 0.25 mm increments, and the deep-drawn samples were visually inspected for the presence or absence of breaks and pinholes while shining a light onto the exterior packaging material. The maximum molding depth at which deep drawing was possible without the occurrence of breaks or pinholes was determined. The molding depth was also evaluated according to the following criteria, with a grade of fair or better considered to be acceptable. The results are shown in Table 3. <Evaluation criteria> ◎: Maximum molding depth is 4.00mm or more ○: Maximum molding depth is 3.50 mm or more and less than 4.00 mm △: Maximum molding depth is 3.00mm or more and less than 3.50mm ×: Maximum molding depth is less than 3.00 mm

[0123] [Heat resistance after deep drawing] The packaging materials (five specimens each) with a forming depth of 2.00 mm obtained in the above evaluation of "deep drawability" were stored for one week while heated to 80°C or 150°C. After that, the extent of delamination between the substrate layer and the metal foil layer was visually inspected while shining a light on the vicinity of the forming convex portion. This test was evaluated according to the following criteria. The results are shown in Table 3. <Evaluation criteria> ○: Delamination occurred in 0 to 1 out of 5 samples △: Delamination occurred in 2 to 4 out of 5 samples ×: Delamination occurred in 5 out of 5 specimens

[0124] [Heat-resistant seal strength] The packaging material was cut into a 120 mm x 60 mm size, folded in half with the sealant layer facing inward, and the edge opposite the folded portion was heat-sealed to a 10 mm width at 190°C / 0.5 MPa / 3 seconds. The material was then stored at room temperature for 6 hours. A 15 mm wide x 300 mm long sample was then cut from the longitudinal center of the heat-sealed portion to prepare a sample for measuring heat-seal strength. This sample was then left in a test environment at 150°C for 5 minutes, after which a T-peel test was performed on the heat-sealed portion of the sample using a tensile tester (manufactured by Shimadzu Corporation) at a tensile speed of 50 mm / min. The heat-seal strength was then evaluated according to the following criteria. The results are shown in Table 3. <Evaluation criteria> ◎: Heat seal strength is 15N / 15mm or more ○: Heat seal strength is 10N / 15mm or more, less than 15N / 15mm △: Heat seal strength is 5N / 15mm or more and less than 10N / 15mm ×: Heat seal strength is less than 5N / 15mm

[0125] [Table 1]

[0126] [Table 2]

[0127] [Table 3] [Explanation of symbols]

[0128] 1... battery element, 2... lead, 10... exterior material (exterior material for electricity storage device), 11... base material layer, 12... first adhesive layer, 13... metal foil layer, 14a, 14b... corrosion prevention treatment layer, 15... second adhesive layer, 16... sealant layer, 30... embossed type exterior material, 32... molding processing area (recess), 34... lid portion, 40... secondary battery

Claims

1. An exterior material for an electricity storage device, a substrate layer; a first adhesive layer; a metal foil layer; a second adhesive layer; and a sealant layer; in this order, the first adhesive layer and the second adhesive layer contain a urethane-based compound that is a reaction product of a polyol-based resin and a polyisocyanate compound, In the first adhesive layer and the second adhesive layer, 2250 to 2290 cm －１ The infrared absorption spectrum peak intensity is A, 1680 to 1720 cm －１ where B is the infrared absorption spectrum peak intensity of the compound, and X defined in the following formula (1) is 10 to 90, The exterior material, wherein the glass transition temperature of the first adhesive layer and the second adhesive layer is 60 to 80°C. X={B / (A+B)}×100...(1)

2. The exterior packaging material according to claim 1 , wherein the polyol-based resin is a polyester polyol-based resin.

3. The packaging material according to claim 1 or 2, further comprising a corrosion prevention treatment layer at least between the second adhesive layer and the metal foil layer.

4. The packaging material according to any one of claims 1 to 3, wherein the sealant layer contains at least one of a polyolefin-based resin and a polyester-based resin.

5. The exterior packaging material according to any one of claims 1 to 4, wherein the sealant layer contains a polyester-based resin.

6. The exterior packaging material according to any one of claims 1 to 5, wherein the polyisocyanate compound includes an aromatic polyisocyanate compound.

7. The exterior packaging material according to any one of claims 1 to 6, wherein the polyisocyanate compound includes an adduct of an aromatic polyisocyanate compound.

8. The packaging material according to any one of claims 1 to 7, wherein at least the second adhesive layer comprises a hydrogen sulfide adsorbing material.

9. The exterior material according to any one of claims 1 to 8, which is for an all-solid-state battery.

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