Exterior material for power storage device

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 a lamination structure having a base material layer, a first adhesive layer, a metal foil layer, a second adhesive layer and a sealant layer in order, wherein the first adhesive layer and the second adhesive layer contain an urethane-based compound which is a reactant of a polyol-based resin and a polyisocyanate compound, in the first adhesive layer and the second adhesive layer, when infrared absorption spectrum peak intensity at 2,250 to 2,290 cm-1 is represented by A, and 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, the glass transition temperatures of the first adhesive layer and the second adhesive layer are 60 to 80°C, and the polyisocyanate compound contains an aromatic polyisocyanate compound. 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 storage batteries, as well as electrochemical capacitors such as electric double layer capacitors. Due to the miniaturization of portable devices or the limitations of installation space, there is a demand for further miniaturization of power storage devices, and lithium ion batteries with high energy density have been attracting attention. As an exterior material for lithium ion batteries, multilayer films that are lightweight, have high heat dissipation properties, and can be produced at low cost have come to be used.

[0003] A lithium ion battery using the above multilayer film as an exterior material is called a laminated lithium ion battery. The exterior material covers the battery contents (positive electrode, separator, negative electrode, electrolyte, etc.) and prevents moisture from penetrating into the battery. A laminated lithium ion battery is manufactured, for example, by forming a recess in a 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] JP 2013-101765 A 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. An all-solid-state battery is characterized by using a solid electrolyte as the electrolyte, rather than an organic electrolyte. While a lithium-ion battery cannot be used at temperatures higher than the boiling point of the electrolyte (about 80°C), an all-solid-state battery can be used at temperatures exceeding 100°C, and the conductivity of lithium ions can be increased by operating it under high temperature conditions (for example, 100 to 150°C).

[0006] However, when using such a laminated body as an exterior material to manufacture a laminate-type all-solid-state battery, delamination may occur between layers of the exterior material (particularly, between the base 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] In addition, in such all-solid-state batteries, the deeper the recesses formed by cold forming, the more battery contents can be accommodated, and therefore the energy density can be increased. 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 consideration of the above problems, and has an object to provide an exterior material that has excellent heat resistance and sufficient deep draw formability. [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, the first adhesive layer and the second adhesive layer containing a urethane-based compound which is a reaction product of a polyol-based resin and a polyisocyanate compound, and a surface roughness of 2250 to 2290 cm -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 exterior packaging material for an electricity storage device has excellent heat resistance and sufficient deep drawability. The present 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 force. In addition, 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 a 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 the metal foil layer, etc., and the occurrence of fine fracture of the adhesive layer can be suppressed.

[0013] As a result, the above 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 draw formability.

[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 more esters derived from dicarboxylic acids (polar groups) in the molecule, and therefore have high hydrogen bonding strength, which improves the adhesion between the adhesive layer and the base layer, sealant layer, and metal foil layer. As a result, the resulting exterior 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, whereby the resulting packaging material has better deep drawability and is less susceptible to delamination between layers of the packaging material (particularly between the substrate layer or sealant layer and the metal foil layer) even under high temperature conditions (e.g., 100 to 150°C), resulting in better heat resistance.

[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 having a high melting point, the resulting exterior material has excellent heat resistance, and when the sealant layer contains a polyester resin having a higher melting point, the resulting exterior material has even more excellent heat resistance.

[0017] In the present invention, the polyisocyanate compound may contain an aromatic polyisocyanate compound, or may contain an adduct of an aromatic polyisocyanate compound. When the polyisocyanate compound contains these compounds, π-π stacking action between aromatic rings in the molecules or π-H interaction occurs, and the cohesive strength of the adhesive layer is improved. Therefore, when the polyisocyanate compound contains an aromatic polyisocyanate compound or an adduct thereof, the resulting exterior material has excellent heat resistance. In addition, since the adduct of the aromatic polyisocyanate compound has active hydrogen in the molecule, hydrogen bonding occurs between the interface of the adhesion target and the active hydrogen, thereby improving the adhesive strength of the interface. As a result, the resulting exterior material has even better heat resistance.

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

[0019] The present invention may be for an all-solid-state battery. The exterior 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. Effect of the Invention

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

[0021] [Figure 1] 1 is a schematic cross-sectional view of an exterior material for an electricity storage device according to one embodiment of the present invention. [Diagram 2]FIG. 1 is a diagram 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). [Diagram 3] 1A and 1B are perspective views showing a process for 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 a state in which the exterior material for an electricity storage device is prepared, (b) shows a state in which an embossed exterior material for an electricity storage device and a battery element are prepared, (c) shows a state in which a part of the exterior material for an electricity storage device is folded back and the end portion is melted, and (d) shows a state in which both sides of the folded back part are folded back upward. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[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 duplicated explanations will be omitted.

[0023] [Exterior materials for power storage devices] FIG. 1 is a cross-sectional view showing a schematic diagram of an embodiment of the exterior material for a power storage device of the present invention. As shown in FIG. 1, the exterior material (exterior material for a power storage device) 10 of this embodiment is a laminate including a base layer 11, a first adhesive layer 12 provided on one side of the base layer 11, a metal foil layer 13 having corrosion prevention treatment layers 14a, 14b on both sides provided on the side opposite the base layer 11 of the first adhesive layer 12, a second adhesive layer 15 provided on the side opposite the first adhesive layer 12 of the metal foil layer 13, and a sealant layer 16 provided on the side opposite the metal foil layer 13 of the second adhesive layer 15. Here, the corrosion prevention treatment layer 14a is provided on the surface of the metal foil layer 13 facing the first adhesive layer 12, and the corrosion prevention treatment layer 14b is provided on the surface of the metal foil layer 13 facing the second adhesive layer 15. In the exterior material 10, the base layer 11 is the outermost layer, and the sealant layer 16 is the innermost layer. That is, the exterior material 10 is 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 layer 11 imparts heat resistance in a sealing process when manufacturing an electricity storage device and plays a role in suppressing the occurrence of pinholes that may occur during molding and distribution. In particular, in the case of an exterior material for a large-scale electricity storage device, the base layer 11 can also impart scratch resistance, chemical resistance, insulation, and the like.

[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 suppress deterioration of the appearance due to melting of the base layer 11 (outer layer) during heat sealing. When the sealant layer 16 has a multi-layer structure, the peak melting temperature of the sealant layer 16 means 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 in the above range include nylon films, PET films, polyamide films, polyphenylene sulfide films (PPS films), polyimide films, polyester films, etc. The peak melting temperature means 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., a flame retardant, a slip agent, an antiblocking agent, an antioxidant, a light stabilizer, a tackifier, 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 caused by 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 provided with the corrosion prevention treatment layer 14a to the base material layer 11. The first adhesive layer 12 has an adhesive strength required to firmly bond the base material layer 11 to the metal foil layer 13, and also has a conformability to prevent the metal foil layer 13 from being broken by the base material layer 11 during cold forming. The conformability refers to the property that the first adhesive layer 12 remains 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 forming the first adhesive layer 12 include urethane-based compounds and polyolefin-based resins. The adhesive components may be used alone or in combination of two or more. The urethane-based compounds are obtained by reacting a polyol-based resin as a base agent with a polyisocyanate compound as a curing agent.

[0031] Examples of the polyol-based resin 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, since it improves the adhesion between the adhesive layer and the sealant layer and the metal foil layer, and the resulting exterior material has 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-based resins include those produced by addition polymerization of ethylene oxide or propylene oxide to propylene glycol, glycerin, pentaerythritol, or the like.

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

[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 in order 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, and the carboxy group is particularly preferred.

[0037] Examples of acid-modified polyolefin resins in which a carboxy group has been introduced into a polyolefin resin 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 the unsaturated carboxylic acid 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 esters of unsaturated carboxylic acids or their acid anhydrides include methyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dimethyl maleate, monomethyl maleate, diethyl fumarate, dimethyl itaconate, diethyl citracone, 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 with respect to 100 parts by mass of the polyolefin resin.

[0042] The polyisocyanate compound contains a plurality of isocyanate groups and serves to crosslink the polyol resin. The polyisocyanate compound may be used alone or in combination of two or more. Examples of the polyisocyanate compound include an aliphatic polyisocyanate compound, an alicyclic polyisocyanate compound, and an aromatic polyisocyanate compound. Since the heat resistance of the resulting exterior material is improved, an aromatic polyisocyanate compound is preferable.

[0043] Examples of the aliphatic polyisocyanate compound include hexamethylene diisocyanate (HDI) and xylylene diisocyanate (XDI). Examples of the alicyclic polyisocyanate compound include isophorone diisocyanate (IPDI). Examples of the aromatic polyisocyanate compound include tolylene diisocyanate (TDI) and diphenylmethane diisocyanate (MDI). The polyisocyanate compound may also be a multimer (e.g., a trimer) of these compounds, and specifically, an adduct, a biuret, an isocyanurate, or the like may be used. The polyisocyanate compound is preferably an adduct, since the adhesive strength at the interface between the adhesive layer and the object to be adhered is improved, and the heat resistance of the resulting exterior material is improved.

[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, and more preferably 10-30.

[0045] A catalyst may be used to control the reaction when the polyol resin, which is the base agent, reacts with moisture contained in the composition containing the base agent and the curing agent or in the air, generating an amine compound, which may then react with the polyisocyanate compound and self-condense. However, the use of a catalyst can suppress the progression of these side reactions. As a result, the ratio 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 adsorbing substance, since it can suppress corrosion of the metal foil layer 13 caused by hydrogen sulfide present outside the packaging material. Examples of such hydrogen sulfide adsorbing substances include zinc oxide and potassium permanganate. When the first adhesive layer 12 contains a hydrogen sulfide adsorbing substance, it is preferable that the content of the hydrogen sulfide adsorbing substance is 1 to 50 mass% with respect to the total amount of the first adhesive layer 12, since it can suppress corrosion of the metal foil layer 13 caused by hydrogen sulfide present outside the packaging material.

[0047] The thickness of the first adhesive layer 12 is preferably from 1 to 10 μm, and more preferably from 2 to 6 μm, from the viewpoint of obtaining 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 above-mentioned adhesive component base agent and a curing agent. The application method can be a known method, such as 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-based resin, 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 group is preferably 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 and the sealant layer 16.

[0053] Examples of adhesive components forming 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 adsorbing substance because the second adhesive layer 15 can suppress corrosion of the metal foil layer 13 caused by hydrogen sulfide generated from the battery contents inside the exterior material. Examples of such hydrogen sulfide adsorbing substances include the same hydrogen sulfide adsorbing substances as those listed for the first adhesive layer 12. The content of the hydrogen sulfide adsorbing substance can be set to the same range as the content of the hydrogen sulfide adsorbing substance 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 in 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 temperature of the first adhesive layer and the second adhesive layer is 60 to 80° C., and since the resulting packaging material has even better deep draw formability, it 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 processability such as moisture resistance and ductility, and cost, it is preferable that the metal foil layer 13 is an aluminum foil. 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 material 10 having better pinhole resistance and ductility can be obtained. When the iron content is 9.0% by mass or less, an exterior material 10 having better flexibility can be obtained.

[0062] As the aluminum foil, a soft aluminum foil that has been annealed is more preferable because it can impart the 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 a desired electrolyte resistance. In addition, in order to simplify the manufacturing process, it is preferable that the metal foil has a surface that is not etched. As the degreasing treatment, for example, a wet type degreasing treatment or a dry type degreasing treatment can be used, but from the viewpoint of simplifying the manufacturing process, a dry type degreasing treatment is preferable.

[0064] As an example of the dry-type degreasing treatment, there is a method in which the degreasing treatment is performed by extending the treatment time in the process of annealing 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 a flame treatment or a 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] As the wet-type degreasing treatment, for example, an acid degreasing treatment, an alkaline degreasing treatment, etc. can be used. As the acid used in the acid degreasing treatment, for example, an inorganic acid such as sulfuric acid, nitric acid, hydrochloric acid, hydrofluoric acid, etc. can be used. These acids may be used alone or in combination of two or more. As the alkali used in the alkaline degreasing treatment, for example, sodium hydroxide, which has a high etching effect, can be used. The alkaline degreasing treatment may be performed using a weak alkaline material and a material containing a surfactant, etc. The above-described wet-type degreasing treatment can be performed by, for example, a dipping method or a spraying 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 subjected to stress 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 caused by the electrolytic solution or a corrosive liquid or gas, such as hydrofluoric acid, generated by a reaction between the electrolytic solution and moisture. 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 having the same configuration or layers having different configurations.

[0069] The corrosion prevention treatment layers 14a, 14b can be formed, for example, by carrying out a degreasing treatment, a hydrothermal conversion 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 a layer that serves as the base material of the corrosion prevention treatment layers 14a, 14b, or a corrosion prevention treatment that is a combination of these treatments.

[0070] Among the above-mentioned treatments, the degreasing treatment, the hydrothermal conversion treatment, and the anodizing treatment, particularly the hydrothermal conversion treatment and the anodizing treatment, are treatments in which the surface of the metal foil (aluminum foil) is dissolved by a treatment agent to form a metal compound (aluminum compound (boehmite, anodized aluminum)) having excellent corrosion resistance. For this reason, such treatments may be included in the definition of chemical conversion treatment in order to obtain a structure in which the metal foil layer 13 and the corrosion prevention treatment layers 14a and 14b form a co-continuous structure.

[0071] Examples of the degreasing treatment include acid degreasing and alkaline degreasing. Examples of the 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. In addition, by using an acid degreasing agent obtained by dissolving a fluorine-containing compound such as monosodium ammonium difluoride in the inorganic acid, it is possible to form a fluoride of a metal that is in a passive state as well as to degrease the metal foil layer 13, which is effective in terms of hydrofluoric acid resistance. Examples of the alkaline degreasing include a method using sodium hydroxide or the like.

[0072] The hydrothermal conversion treatment may be, for example, a boehmite treatment obtained by immersing the metal foil layer 13 in boiling water to which triethanolamine has been added. The anodizing treatment may be, for example, an alumite 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 that the hydrothermal conversion treatment, the anodizing treatment, and the chemical conversion treatment are preceded by the above-mentioned degreasing treatment.

[0073] The chemical conversion treatment is not limited to a wet method, and may be, for example, a method in which a treatment agent used in the treatment is mixed with a resin component and then applied. In addition, the corrosion prevention treatment is preferably a coating type chromate treatment from the viewpoint of maximizing the 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, a method using a coating agent containing a rare earth element oxide sol is preferred.

[0075] The mass per unit area of ​​the corrosion prevention layers 14a and 14b is 0.005 to 0.200 g / m 2The range of 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 is saturated and no further effect can be expected. Note that the above information is given in terms of mass per unit area, but if the specific gravity is known, it is possible to convert the thickness from that.

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

[0077] <Sealant layer 16> The sealant layer 16 is a layer that imparts heat-sealing sealability to the exterior material 10, and is a layer that is placed on the inside and heat-sealed (thermally fused) when the electricity storage device is assembled.

[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 the heat resistance of the resulting exterior material is further improved.

[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-, medium- and high-density polyethylenes, 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-based resins include polyethylene terephthalate (PET) and polybutylene terephthalate (PBT), etc. These polyester-based 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 according to 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 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 end of the packaging material can be reduced.

[0085] The peak melting temperature of the sealant layer 16 is preferably 200 to 280° C. because this improves the 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 exterior 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 via a second adhesive layer 15.

[0088] <Process S11> In step S11, a corrosion prevention treatment layer 14a is formed on one side of the metal foil layer 13, and a corrosion prevention treatment layer 14b is formed on the other side 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 sides of the metal foil layer 13, and then drying, hardening, and baking are performed in sequence to form the corrosion prevention treatment layers 14a and 14b at the same time. In addition, a corrosion prevention treatment agent may be applied to one side of the metal foil layer 13, and then drying, hardening, and baking are performed in sequence to form the corrosion prevention treatment layer 14a, and then the corrosion prevention treatment layer 14b may be formed in the same manner on the other side of the metal foil layer 13. The order of forming the corrosion prevention treatment layers 14a and 14b is not particularly limited. In addition, the corrosion prevention treatment agent may be different from or the same for the corrosion prevention treatment layer 14a and the corrosion prevention treatment layer 14b. 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 that forms a 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, and may be, for example, 40 to 120°C.

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

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

[0092] [Electricity storage device] Next, an electric storage device including an exterior material 10 as a container will be described. The electric storage device includes a battery element 1 including an electrode, a lead 2 extending from the electrode, and a container for housing the battery element 1, and the container is formed from the exterior material 10 for an electric storage device so that the sealant layer 16 faces the inside. The container may be obtained by overlapping two exterior materials with the sealant layers 16 facing each other and heat-sealing the peripheral portion of the overlapped exterior material 10, or by folding one exterior material and overlapping it, and similarly heat-sealing the peripheral portion of the exterior material 10. The lead 2 is sandwiched and sealed by the exterior material 10 that forms the container with the sealant layer 16 on the inside. The lead 2 may be sandwiched by the exterior material 10 via a tab sealant.

[0093] The exterior material of the present 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, and electrochemical capacitors such as electric double layer capacitors. The exterior material 10 of the present embodiment has excellent deep drawing formability, and is therefore suitable for all-solid-state battery applications in which a recess is formed by cold forming and the battery contents are accommodated in the recess.

[0094] [Method of manufacturing electricity storage device] Next, a method for manufacturing an electricity storage device using the above-mentioned exterior material 10 will be described. Note that, 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. FIG. 3 (a) to (d) 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 the 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 an exterior 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 disposing the battery element 1 on one side of the exterior material 10 to obtain an embossed type exterior 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 clamping the lead 2 is left and the other side is heat-sealed, and then an electrolyte is injected from the remaining side and the remaining side is heat-sealed in a vacuum state (see FIG. 3(c)). Step S25: A step of charging and discharging the battery under predetermined conditions such as current value, voltage value, and ambient temperature to cause a chemical change (chemical conversion). Step S26: A step of cutting the ends of the heat-sealed sides other than the sides that hold the leads 2, and folding them towards the molding processing area (recess 32) side (see FIG. 3(d)).

[0096] <Process S21> In step S21, an exterior material 10, a battery element 1 including electrodes, and a lead 2 extending from the electrodes are prepared. The exterior material 10 is prepared based on the above-described embodiment. There are no particular limitations on the battery element 1 and the lead 2, and a known battery element 1 and lead 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 exterior material 10. The planar shape of the recess 32 is a shape that 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 exterior material 10 in its thickness direction. In addition, the pressing position, i.e., the recess 32, is formed at a position biased toward one end of the exterior material 10 in the longitudinal direction from the center of the exterior material 10 cut into a rectangle. Thereby, 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 method for forming the recesses 32 includes molding (deep drawing) using a mold. As a molding method, a method is exemplified in which a female mold and a male mold are arranged so as to have a gap equal to or greater than the thickness of the exterior material 10, and the male mold is pressed into the female mold together with the exterior material 10. The depth (deep drawing amount) of the recesses 32 can be adjusted to a desired amount by adjusting the pressing amount of the male mold. The embossed type exterior material 30 is obtained by forming the recesses 32 in the exterior material 10. For example, the embossed type exterior material 30 has a shape as shown in FIG. 2. Here, FIG. 2(a) is a perspective view of the embossed type exterior material 30, and FIG. 2(b) is a vertical cross-sectional view taken along the line bb of the embossed type exterior material 30 shown in FIG. 2(a).

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

[0100] After the 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 of the entire packaging material 10. The curing step can be performed at 80 to 150°C.

[0101] The thickness of sealant layer 16 before heat sealing is preferably 40% or more and 80% or less of the thickness of lead 2. When the thickness of sealant layer 16 is equal to or more 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 exterior packaging material 10 of secondary battery 40 can be appropriately suppressed, and the amount of moisture penetrating from the ends of exterior 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 those in step S23.

[0103] <Process S25> In step S25, the secondary battery 40 obtained in step S23 is charged and discharged to cause a chemical change (formation: 3 days in a 40°C environment). Then, in order to remove gas generated by the formation and to replenish the electrolyte, the secondary battery 40 is opened once and then finally sealed. 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 area 32 to form folded back parts 42, thereby obtaining the secondary battery 40.

[0105] Although the preferred embodiments of the exterior 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 variations are possible. EXAMPLES

[0106] The present invention will be described in more detail below with reference to 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 mixed in the ratios shown in Table 2. Details of the base agent and curing agent shown in Tables 1 and 2 are as follows. The following compounds were used as the catalyst and hydrogen sulfide adsorbent. {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 (manufactured by 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., product name: Orgatics TC-401) {Hydrogen sulfide adsorbent} Zinc oxide (manufactured by Ishihara Sangyo Kaisha, Ltd., product name: FZO-50)

[0109] <Corrosion prevention treatment layer> The sodium polyphosphate-stabilized cerium oxide sol was prepared by mixing 10 parts by mass of sodium phosphoric acid with 100 parts by mass of cerium oxide using distilled water as a solvent and adjusting the solid content concentration to 10% by mass.

[0110] <Metal foil layer (thickness 35 μm)> Annealed and degreased soft aluminum foil (manufactured by Toyo Aluminum Co., Ltd., "Material 8079") 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 a dry lamination technique. 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 a dry lamination technique.

[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. Then, the applied sodium polyphosphate-stabilized cerium oxide sol was dried, and then a baking process was carried out in sequence to form a corrosion prevention treatment layer on both sides of the metal foil layer. At this time, 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 the base layer by a dry lamination technique using an adhesive (first adhesive layer). Next, a sealant layer was attached to the other side of the metal foil layer on which the corrosion prevention treatment layer was formed by a dry lamination technique using a (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 ratio] <First adhesive layer> The metal foil layer and the base material layer 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 infrared absorption spectrum peak intensity was designated as B, the urethane abundance ratio (X) was calculated by 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 the 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 exterior material was cut to a width of 15 mm, and the laminate strength between the metal foil layer of the exterior 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 material was heated at 80°C for 5 minutes, and then the laminate strength was measured while still heating at 80°C. Condition 2: The exterior material was heated at 150°C for 5 minutes, and then the laminate strength was measured while still heating at 150°C. Condition 3: The exterior material was heated at 100° C. and exposed to hydrogen sulfide at a concentration of 20 ppm for one week, after which the laminate strength was measured in the same manner 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. ◎: Lamination 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 ×: Lamination strength is less than 1.5N / 15mm

[0122] [Deep drawing formability] <Measurement method> The molding depth at which deep drawing was possible for the exterior materials obtained in each example was evaluated by the following method. The molding depth of the molding device was set to 1.0 to 5.0 mm in increments of 0.25 mm, and the deep-drawn samples were visually checked for the presence or absence of breaks and pinholes while shining a light on the exterior material, and the maximum molding depth at which deep drawing was possible without the occurrence of either breaks or pinholes was determined. The molding depth was also evaluated according to the following criteria, with △ or higher being considered a pass. 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 exterior materials (five specimens each) with a molding depth of 2.00 mm obtained in the above evaluation of [Deep drawability] were stored for one week while being heated to 80°C or 150°C. After that, the occurrence of delamination between the base material layer and the metal foil layer was visually confirmed while shining a light on the vicinity of the molding convex part. 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 samples

[0124] [Heat-resistant seal strength] The exterior material was cut into a size of 120 mm x 60 mm, folded in half so that the sealant layer was on the inside, and the end opposite to the folded part was heat-sealed to a width of 10 mm at 190 ° C / 0.5 MPa / 3 seconds, and stored at room temperature for 6 hours. Then, the longitudinal center part of the heat-sealed part was cut out to a width of 15 mm x length of 300 mm to prepare a sample for measuring heat-seal strength. After leaving this sample in a test environment of 150 ° C for 5 minutes, a T-shaped peel test was performed on the heat-sealed part of the sample using a tensile tester (manufactured by Shimadzu Corporation) at a tensile speed of 50 mm / min. Then, the heat-seal strength was evaluated based on the following evaluation 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, 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] Reference Signs List 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 area (recess), 34...lid, 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 glass transition temperature of the first adhesive layer and the second adhesive layer is 60 to 80°C; the polyisocyanate compound includes an aromatic polyisocyanate compound, The exterior material, wherein the polyisocyanate compound contains a toluylene diisocyanate-adduct as the aromatic polyisocyanate compound. 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 packaging material according to any one of claims 1 to 5, wherein at least the second adhesive layer comprises a hydrogen sulfide adsorbing material.

7. The exterior material according to any one of claims 1 to 6, which is for an all-solid-state battery.

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