JP7772166B2 - Exterior material for power storage device, manufacturing method thereof, power storage device, and polyamide film - Google Patents

Description

This disclosure relates to an exterior material for an electricity storage device, a manufacturing method thereof, an electricity storage device, and a polyamide film.

Various types of electricity storage devices have been developed to date, but in all of these devices, exterior materials are essential components for sealing the electricity storage device elements, such as electrodes and electrolytes. Traditionally, metal exterior materials have been widely used as exterior materials for electricity storage devices.

On the other hand, in recent years, with the increasing performance of electric vehicles, hybrid electric vehicles, personal computers, cameras, mobile phones, and other devices, there has been a demand for energy storage devices to be thinner and lighter, as well as have a variety of shapes. However, the metal exterior materials for energy storage devices that have traditionally been widely used have the drawback of being difficult to adapt to the increasing variety of shapes, and there are also limitations to how light they can be made.

In recent years, therefore, film-like laminates, in which a base layer, a barrier layer, and a heat-sealable resin layer are sequentially laminated, have been proposed as packaging materials for electricity storage devices that can be easily processed into a variety of shapes and can be made thinner and lighter (see, for example, Patent Document 1).

In such electrical storage device packaging materials, recesses are generally formed by cold forming, and electrical storage device elements such as electrodes and electrolyte are placed in the spaces formed by the recesses. The heat-sealable resin layer is then heat-sealed to obtain an electrical storage device in which the electrical storage device elements are housed inside the electrical storage device packaging material.

Japanese Patent Application Laid-Open No. 2008-287971

Electricity storage device elements contain components such as rare metals, and demand for these components is rapidly increasing. For this reason, when replacing an electricity storage device in various products such as electrical equipment, there is a need to remove the device from the product and recover and reuse the various components contained in the electricity storage device element.

In various products such as electrical equipment, electricity storage devices are firmly fixed to the product's housing using double-sided tape, adhesives, etc. For this reason, when removing an electricity storage device from the product's housing, a large external force is applied to the electricity storage device. Specifically, electricity storage devices are generally removed from the housing using a metal spatula, etc., and a large external force is applied to the electricity storage device. If a large external force is applied to an exterior material for an electricity storage device made of a film-like laminate when removing the electricity storage device, there is a risk that the exterior material for an electricity storage device will be damaged.

Under these circumstances, the primary objective of this disclosure is to provide an exterior material for an electricity storage device that is less likely to be damaged when the electricity storage device is peeled off from the housing after being fixed to the housing with double-sided tape or the like.

The inventors of the present disclosure conducted extensive research to solve the above-mentioned problems. As a result, they discovered that an electrical storage device packaging material that is composed of a laminate including, in order from the outside, at least a base layer, a barrier layer, and a heat-sealable resin layer, wherein the base layer contains a polyamide film, and the crystallization index of the polyamide film measured from the outside of the base layer by the ATR method of Fourier transform infrared spectroscopy is equal to or greater than a predetermined value, is less likely to be damaged when the electrical storage device is peeled from the housing after being fixed to the housing with double-sided tape or the like.

The present disclosure has been completed based on these findings and further investigations. That is, the present disclosure provides the inventions of the following aspects.
The laminate is composed of at least a base layer, a barrier layer, and a heat-sealable resin layer, in this order from the outside,
the substrate layer includes a polyamide film,
An outer casing material for an electricity storage device, wherein the polyamide film has a crystallization index of 1.50 or more as measured from the outside of the base material layer by an ATR method of Fourier transform infrared spectroscopy.

The present disclosure makes it possible to provide an exterior material for an electricity storage device that is less likely to be damaged when an electricity storage device fixed to a housing with double-sided tape or the like is peeled off from the housing with a metal spatula or the like. The present disclosure also makes it possible to provide a method for manufacturing the exterior material for an electricity storage device, an electricity storage device that uses the exterior material for an electricity storage device, and a polyamide film suitable for use as a substrate layer in the exterior material for an electricity storage device.

1 is a schematic diagram showing an example of a cross-sectional structure of an exterior packaging material for an electricity storage device according to the present disclosure. 1 is a schematic diagram showing an example of a cross-sectional structure of an exterior packaging material for an electricity storage device according to the present disclosure. 1 is a schematic diagram showing an example of a cross-sectional structure of an exterior packaging material for an electricity storage device according to the present disclosure. 1 is a schematic diagram showing an example of a cross-sectional structure of an exterior packaging material for an electricity storage device according to the present disclosure. 5A to 5C are schematic diagrams illustrating a procedure for producing a sample used in a peel test of an electricity storage device in an example. 1A and 1B are a side view and a plan view, respectively, of a sample used in a peel test of an electricity storage device in an example. 1A and 1B are a side view and a plan view of a sample used in a peel test of an electricity storage device according to an example, with a double-sided tape attached thereto. FIG. 10 is a schematic diagram illustrating how an electricity storage device is peeled off from a stainless steel plate using a metal spoon in a peel test of the electricity storage device in the examples.

The electrical storage device packaging material of the present disclosure is composed of a laminate including, in order from the outside, at least a base material layer, a barrier layer, and a heat-sealable resin layer, and is characterized in that the base material layer contains a polyamide film, and the polyamide film has a crystallization index of 1.50 or greater as measured from the outside of the base material layer by the ATR method of Fourier transform infrared spectroscopy. The electrical storage device packaging material of the present disclosure is prevented from being damaged when the electrical storage device is peeled from the housing after being fixed to the housing with double-sided tape or the like.

The exterior packaging material for an electricity storage device disclosed herein is described in detail below. Note that in this specification, numerical ranges indicated by "to" mean "greater than or equal to" or "less than or equal to." For example, the expression "2 to 15 mm" means 2 mm or greater and 15 mm or less.

1. Laminated Structure and Physical Properties of the Electricity Storage Device Exterior Material As shown in FIG. 1 , the exterior packaging material 10 for an electricity storage device according to the present disclosure is composed of a laminate including, in order from the outside, a base material layer 1, a barrier layer 3, and a heat-sealable resin layer 4. In the exterior packaging material 10 for an electricity storage device, the base material layer 1 is the outermost layer, and the heat-sealable resin layer 4 is the innermost layer. When assembling an electricity storage device using the exterior packaging material 10 for an electricity storage device and an electricity storage device element, the heat-sealable resin layers 4 of the exterior packaging material 10 for an electricity storage device are placed opposite each other, and the peripheral portions are heat-sealed to form a space, in which the electricity storage device element is housed. In the laminate constituting the exterior packaging material 10 for an electricity storage device according to the present disclosure, the barrier layer 3 is used as the reference, and the heat-sealable resin layer 4 side is the inner side relative to the barrier layer 3, and the base material layer 1 side is the outer side relative to the barrier layer 3.

As shown in Figures 2 to 4, the exterior packaging material 10 for an electricity storage device may optionally have an adhesive layer 2 between the base layer 1 and the barrier layer 3 to improve adhesion between these layers. As shown in Figures 3 and 4, an adhesive layer 5 may optionally be provided between the barrier layer 3 and the heat-sealable resin layer 4 to improve adhesion between these layers. As shown in Figure 5, a surface coating layer 6 may be provided on the outer side of the base layer 1 (the side opposite the heat-sealable resin layer 4) as needed.

The thickness of the laminate constituting the electrical storage device exterior material 10 is not particularly limited, but from the viewpoints of cost reduction and improved energy density, the upper limit is preferably approximately 180 μm or less, approximately 155 μm or less, or approximately 120 μm or less. From the viewpoint of maintaining the function of the electrical storage device exterior material to protect the electrical storage device elements, the lower limit is preferably approximately 35 μm or more, approximately 45 μm or more, or approximately 60 μm or more. Preferred ranges include, for example, approximately 35 to 180 μm, approximately 35 to 155 μm, approximately 35 to 120 μm, approximately 45 to 180 μm, approximately 45 to 155 μm, approximately 45 to 120 μm, approximately 60 to 180 μm, approximately 60 to 155 μm, and approximately 60 to 120 μm. Of these, 60 to 120 μm is particularly preferred.

In the electrical storage device exterior material 10, the ratio of the total thickness of the base material layer 1, optional adhesive layer 2, barrier layer 3, optional adhesive layer 5, heat-sealable resin layer 4, and optional surface coating layer 6 to the thickness (total thickness) of the laminate constituting the electrical storage device exterior material 10 is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more. As a specific example, when the electrical storage device exterior material 10 of the present disclosure includes the base material layer 1, adhesive layer 2, barrier layer 3, adhesive layer 5, and heat-sealable resin layer 4, the ratio of the total thickness of these layers to the thickness (total thickness) of the laminate constituting the electrical storage device exterior material 10 is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more.

The substrate layer 1 of the electrical storage device exterior material 10 of the present disclosure contains a polyamide film, and the crystallization index of the polyamide film measured from the outside of the substrate layer 1 by the ATR method of Fourier transform infrared spectroscopy is 1.50 or greater. The method for measuring the crystallization index of the substrate layer 1 of the electrical storage device exterior material 10 of the present disclosure is as follows.

<Measurement of Crystallization Index of Base Material Layer of Exterior Material for Electricity Storage Device>
The electrical storage device casing material is cut into a 100 mm x 100 mm square to prepare a sample. The surface of the polyamide film located on the outside of the obtained sample is subjected to infrared absorption spectrum measurement using the ATR measurement mode of an FT-IR at a temperature of 25°C and a relative humidity of 50%. As an apparatus, for example, a Nicolet iS10 manufactured by Thermo Fisher Scientific Co., Ltd. can be used. From the obtained absorption spectrum, a peak intensity P near 1200 cm ⁻¹ resulting from absorption of α-crystals of nylon and a peak intensity Q near 1370 cm ⁻¹ resulting from absorption unrelated to crystals are measured, and the intensity ratio X = P/Q of the peak intensity P to the peak intensity Q is calculated as the crystallization index. Note that when the electrical storage device casing material is obtained from an electrical storage device to measure the crystallization index of the base layer, the electrical storage device casing material is obtained from the top or bottom surface of the electrical storage device, rather than from the heat-sealed portion or side surface, to prepare the sample.
(Measurement conditions)
Method: Macro ATR method Wavenumber resolution: 8cm ^-1
Number of integrations: 32 times Detector: DTGS detector ATR prism: Ge
Incident angle: 45°
Baseline: Obtained as a linear approximation between wave numbers 1100 cm ⁻¹ and 1400 cm ⁻¹ .
Absorption peak intensity Y ₁₂₀₀ : the value obtained by subtracting the baseline value from the maximum peak intensity in the wavenumber range of 1195 cm ⁻¹ to 1205 cm ⁻¹ Absorption peak intensity Y ₁₃₇₀ : the value obtained by subtracting the baseline value from the maximum peak intensity in the wavenumber range of 1365 cm ⁻¹ to 1375 cm ⁻¹

When the outer surface of the electricity storage device packaging material 10 is made up of the polyamide film of the base material layer 1, the electricity storage device packaging material 10 can be used as is to measure the crystallization index. Furthermore, when the outer surface of the electricity storage device packaging material 10 is not made up of the polyamide film of the base material layer 1, such as when the base material layer 1 has a multilayer structure as described below and a resin film other than the polyamide film (e.g., a polyester film) is located outside the polyamide film, or when the surface coating layer 6 described below is laminated on the outside of the base material layer 1, the layer located outside the polyamide film can be removed from the electricity storage device packaging material 10 to expose the surface of the polyamide film, and the crystallization index can be measured.

In the electrical storage device packaging material 10, the crystallization index may be 1.50 or greater. However, from the viewpoint of more effectively preventing damage to the electrical storage device packaging material during peeling, it is more preferably 1.55 or greater, even more preferably 1.60 or greater, and particularly preferably 1.65 or greater. There is no particular upper limit to the crystallization index, but examples include 2.50 or less and 1.80 or less. Preferred ranges for the crystallization index include, for example, 1.50 to 2.50, 1.60 to 2.50, 1.65 to 2.50, 1.50 to 1.80, 1.60 to 1.80, and 1.65 to 1.80.

Methods for increasing the crystallization index of the polyamide film contained in the base material layer 1 of the electrical storage device exterior material 10 to 1.50 or higher include promoting crystallization (promoting the formation of α crystals) by adjusting the stretching ratio, heat setting temperature, and post-heating temperature and time during the polyamide film manufacturing process.

2. Layers forming the exterior material for an electricity storage device [Base layer 1]
In the present disclosure, the substrate layer 1 is a layer provided for the purpose of allowing the packaging material for an electricity storage device to function as a substrate. The substrate layer 1 is located on the outer layer side of the packaging material for an electricity storage device.

The substrate layer 1 contains a polyamide film. As described above, the crystallization index of the polyamide film measured from the outside of the substrate layer 1 by the ATR method of Fourier transform infrared spectroscopy is 1.50 or greater.

The polyamide used to form the polyamide film may be any polyamide having α crystals, and specific examples include aliphatic polyamides such as nylon 6, nylon 66, nylon 46, and copolymers of nylon 6 and nylon 66. These polyamides may be used alone or in combination of two or more. The polyamide film is preferably a nylon film.

The polyamide film may be an unstretched film or a stretched film. When the base material layer 1 includes an unstretched film, the unstretched film may be formed by extrusion molding when laminating each layer of the electrical storage device exterior material 10, or a pre-prepared unstretched film may be laminated, or a resin (polyamide) may be applied to form the unstretched film. Examples of methods for applying the resin include roll coating, gravure coating, and extrusion coating. Furthermore, when the base material layer 1 is a stretched film, a pre-prepared stretched film is laminated when laminating each layer of the electrical storage device exterior material 10. Examples of stretched films include uniaxially stretched films and biaxially stretched films, with biaxially stretched films being preferred. Examples of stretching methods for forming biaxially stretched films include sequential biaxial stretching, inflation, and simultaneous biaxial stretching.

The polyamide film is preferably a biaxially oriented nylon film.

The electrical storage device packaging material 10 of the present disclosure can be manufactured using, as the base layer 1, a polyamide film having a crystallization index of 1.50 or more as measured by the ATR method of Fourier transform infrared spectroscopy. Alternatively, the crystallization index can be increased to 1.50 or more by applying heat to the polyamide film during the manufacturing process of the electrical storage device packaging material 10. As described in the section "5. Polyamide Film" below, the electrical storage device packaging material 10 of the present disclosure is preferably manufactured using, as the base layer 1, a polyamide film having a crystallization index of 1.50 or more as measured by the ATR method of Fourier transform infrared spectroscopy. That is, the electrical storage device packaging material 10 of the present disclosure is preferably manufactured by using, as the base layer 1, a polyamide film whose crystallization index has been adjusted in advance to 1.50 or more, and laminating it with each layer, such as the barrier layer 3 and the heat-sealable resin layer 4. Furthermore, as will be shown in the examples described later, the crystallization index of the polyamide film laminated to the electrical storage device packaging material 10 and included in the base material layer 1 can be made higher than the polyamide film before it is applied to the electrical storage device packaging material 10.

From the perspective of more effectively preventing damage to the electrical storage device packaging material during peeling, the thickness of the polyamide film is preferably at least about 3 μm, more preferably at least about 10 μm, and is preferably no more than about 50 μm, more preferably no more than about 35 μm. Preferred ranges include approximately 3 to 50 μm, approximately 3 to 35 μm, approximately 10 to 50 μm, and approximately 10 to 35 μm, with approximately 10 to 35 μm being particularly preferred.

The substrate layer 1 may further include a resin film different from the polyamide film. Examples of resins that may form the resin film different from the polyamide film include polyester, polyolefin, epoxy resin, acrylic resin, fluororesin, polyurethane, silicone resin, and phenolic resin, as well as modified versions of these resins. The resin may also be a copolymer of these resins or a modified version of the copolymer. Furthermore, it may also be a mixture of these resins. Of these, polyester is preferred.

Specific examples of polyesters include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolymer polyesters. Copolymer polyesters include those in which ethylene terephthalate is the main repeating unit. Specific examples include copolymer polyesters in which ethylene terephthalate is the main repeating unit and is polymerized with ethylene isophthalate (hereinafter abbreviated as polyethylene (terephthalate/isophthalate)), polyethylene (terephthalate/adipate), polyethylene (terephthalate/sodium sulfoisophthalate), polyethylene (terephthalate/sodium isophthalate), polyethylene (terephthalate/phenyl dicarboxylate), and polyethylene (terephthalate/decane dicarboxylate). These polyesters may be used alone or in combination of two or more. Among these, polyethylene terephthalate and polybutylene terephthalate are preferred.

The polyester film is preferably a stretched polyester film, and more preferably a biaxially stretched polyester film.

The polyester film is preferably a biaxially oriented polyethylene terephthalate film or a biaxially oriented polybutylene terephthalate film.

If the base layer 1 further contains a resin film other than the polyamide film, the thickness of the other resin film is not particularly limited as long as it does not impair the effects of the present invention. It is preferably at least about 3 μm, more preferably at least about 10 μm, and is preferably at most about 50 μm, more preferably at most about 35 μm. Preferred ranges include approximately 3 to 50 μm, approximately 3 to 35 μm, approximately 10 to 50 μm, and approximately 10 to 35 μm, with approximately 10 to 35 μm being particularly preferred.

The substrate layer 1 may be a single layer or may be composed of two or more layers as long as it contains polyamide film, but from the perspective of making the electrical storage device exterior material 10 thinner, a single layer of polyamide film is preferred.

When the base layer 1 is composed of two or more layers, the base layer 1 may be a laminate in which resin films are laminated with an adhesive or the like, or a laminate of resin films formed by co-extrusion of resins into two or more layers. Furthermore, a laminate of resin films formed by co-extrusion of resins into two or more layers may be used as the base layer 1 in its unstretched state, or may be uniaxially or biaxially stretched to form the base layer 1.

Specific examples of laminates of two or more resin films in the base layer 1 include laminates of polyester film and nylon film, and laminates of two or more nylon film layers. A laminate of stretched nylon film and stretched polyester film, or a laminate of two or more stretched nylon film layers is preferred. For example, when the base layer 1 is a laminate of two resin films, a laminate of polyamide resin film and polyamide resin film, or a laminate of polyester resin film and polyamide resin film, is preferred, and a laminate of nylon film and nylon film, or a laminate of polyethylene terephthalate film and nylon film, is more preferred. Furthermore, because polyester resins are less likely to discolor when electrolyte solution adheres to their surface, for example, when the base layer 1 is a laminate of two or more resin films, it is preferred that the polyester resin film be the outermost layer of the base layer 1.

When the base layer 1 is a laminate of two or more resin film layers, the two or more resin film layers may be laminated via an adhesive. Examples of preferred adhesives include those similar to those exemplified for adhesive layer 2, described below. The method for laminating two or more resin film layers is not particularly limited, and known methods can be used, such as dry lamination, sandwich lamination, extrusion lamination, and thermal lamination, with dry lamination being preferred. When laminating using the dry lamination method, a polyurethane adhesive is preferably used as the adhesive. In this case, the adhesive thickness can be, for example, approximately 2 to 5 μm. Alternatively, an anchor coat layer can be formed on the resin film before lamination. Examples of the anchor coat layer include those similar to those exemplified for adhesive layer 2, described below. In this case, the anchor coat layer thickness can be, for example, approximately 0.01 to 1.0 μm.

Additives such as lubricants, flame retardants, antiblocking agents, antioxidants, light stabilizers, tackifiers, and antistatic agents may also be present on at least one of the surface and interior of the base layer 1. A single type of additive may be used, or two or more types may be mixed together.

In the present disclosure, from the viewpoint of improving the formability of the exterior material for an electrical storage device, it is preferable that a lubricant be present on the surface of the base material layer 1. The lubricant is not particularly limited, but preferably an amide-based lubricant is used. Specific examples of amide-based lubricants include saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, methylolamides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, fatty acid ester amides, and aromatic bisamides. Specific examples of saturated fatty acid amides include lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, and hydroxystearic acid amide. Specific examples of unsaturated fatty acid amides include oleic acid amide and erucic acid amide. Specific examples of substituted amides include N-oleyl palmitic acid amide, N-stearyl stearic acid amide, N-stearyl oleic acid amide, N-oleyl stearic acid amide, and N-stearyl erucic acid amide. Specific examples of methylolamides include methylol stearic acid amide. Specific examples of saturated fatty acid bisamides include methylene bisstearic acid amide, ethylene biscapric acid amide, ethylene bislauric acid amide, ethylene bisstearic acid amide, ethylene bishydroxystearic acid amide, ethylene bisbehenic acid amide, hexamethylene bisstearic acid amide, hexamethylene bisbehenic acid amide, hexamethylene hydroxystearic acid amide, N,N'-distearyl adipamide, N,N'-distearyl sebacic acid amide, etc. Specific examples of unsaturated fatty acid bisamides include ethylene bisoleic acid amide, ethylene biserucic acid amide, hexamethylene bisoleic acid amide, N,N'-dioleyl adipamide, N,N'-dioleyl sebacic acid amide, etc. Specific examples of fatty acid ester amides include stearamidoethyl stearate, etc. Specific examples of aromatic bisamides include m-xylylene bisstearic acid amide, m-xylylene bishydroxystearic acid amide, N,N'-distearyl isophthalic acid amide, etc. The lubricants may be used singly or in combination of two or more.

When a lubricant is present on the surface of the base layer 1, the amount thereof is not particularly limited, but is preferably about 3 mg/ ^m2 or more, more preferably about 4 to 15 mg/ ^m2 , and even more preferably about ⁵ to 14 mg/m2.

The lubricant present on the surface of the base layer 1 may be a lubricant exuded from the resin that makes up the base layer 1, or a lubricant applied to the surface of the base layer 1.

The total thickness of the substrate layer 1 is not particularly limited as long as it functions as a substrate, but examples include approximately 3 to 50 μm, and preferably approximately 10 to 35 μm.

[Coating layer]
The electrical storage device packaging material of the present disclosure may, if necessary, have a coating layer (not shown) on the substrate layer 1 (the side of the substrate layer 1 opposite the barrier layer 3) for the purpose of improving printability, formability, and the like. The coating layer is provided so as to be in contact with the substrate layer 1. The thickness of the coating layer is not particularly limited as long as it exhibits the above-described function of the coating layer, and examples thereof include about 0.01 to 0.40 μm, preferably about 0.01 to 0.30 μm, and more preferably about 0.1 to 0.30 μm. A thickness of 0.01 μm or more allows a layer of uniform thickness to be formed on the substrate layer 1. As a result, the printing property of the electrical storage device packaging material of the present disclosure does not become uneven, enabling uniform printing, and uniform formability can be obtained.

Examples of resins that can form the coating layer include various synthetic resins such as polyvinylidene chloride, vinylidene chloride-vinyl chloride copolymer, polyolefin, acid-modified polyolefin, polyester, epoxy resin, phenolic resin, fluororesin, cellulose ester, polyurethane, acrylic resin, and polyamide. Of these, polyurethane, polyester, and acrylic resin are preferred.

The coating layer may contain lubricants or additives as needed to improve slipperiness. Examples of lubricants include the same lubricants as those described above. Examples of additives include the same additives as those exemplified for the surface coating layer 6 described below. The content and particle size of these lubricants and additives are adjusted appropriately to match the thickness of the coating layer.

The exterior packaging material for an electricity storage device of the present disclosure may also include a coating layer (not shown) on one side (the barrier layer 3 side of the substrate layer 1 or the side opposite the barrier layer 3 of the substrate layer 1) or both sides of the substrate layer 1, as needed, for the purpose of improving adhesion to the layer adjacent to the substrate layer. That is, the coating layer provided on the substrate layer may be a layer intended to improve printability or formability, or may be a layer intended to improve the adhesiveness of the substrate layer. Even when the coating layer is intended to improve the adhesiveness of the substrate layer, the resin and thickness forming the coating layer may be similar to those described above for the resin and thickness of the coating layer. The aforementioned lubricants and additives may also be included, but if there is an adjacent layer on the opposite side of the coating layer from the substrate layer, it is preferable not to include lubricants or additives.

[Adhesive layer 2]
In the packaging material for an electricity storage device of the present disclosure, the adhesive layer 2 is a layer that is provided between the base layer 1 and the barrier layer 3 as needed for the purpose of increasing the adhesion between them.

The adhesive layer 2 is formed from an adhesive capable of bonding the base layer 1 and the barrier layer 3. There are no limitations on the adhesive used to form the adhesive layer 2, and it may be any of a chemical reaction type, a solvent evaporation type, a hot melt type, a thermocompression type, etc. It may also be a two-component curing adhesive (two-component adhesive), a one-component curing adhesive (one-component adhesive), or a resin that does not involve a curing reaction. The adhesive layer 2 may be a single layer or multiple layers.

Specific examples of adhesive components include polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolymer polyesters; polyethers; polyurethanes; epoxy resins; phenolic resins; polyamides such as nylon 6, nylon 66, nylon 12, and copolymer polyamides; polyolefin resins such as polyolefins, cyclic polyolefins, acid-modified polyolefins, and acid-modified cyclic polyolefins; polyvinyl acetate; cellulose; (meth)acrylic resins; polyimides; polycarbonates; amino resins such as urea resins and melamine resins; rubbers such as chloroprene rubber, nitrile rubber, and styrene-butadiene rubber; and silicone resins. These adhesive components may be used alone or in combination. Among these adhesive components, polyurethane adhesives are preferred. Furthermore, the adhesive strength of these adhesive resins can be increased by using an appropriate curing agent. The curing agent is selected from polyisocyanates, multifunctional epoxy resins, oxazoline group-containing polymers, polyamine resins, acid anhydrides, and other materials depending on the functional groups of the adhesive components.

Examples of polyurethane adhesives include those containing a base agent containing a polyol compound and a curing agent containing an isocyanate compound. Preferred examples include two-component curing polyurethane adhesives that use a polyol such as polyester polyol, polyether polyol, or acrylic polyol as the base agent and an aromatic or aliphatic polyisocyanate as the curing agent. Furthermore, it is preferable to use a polyester polyol that has hydroxyl groups on the side chain in addition to the terminal hydroxyl groups of the repeating unit as the polyol compound. Forming the adhesive layer 2 from a polyurethane adhesive provides the electrical storage device exterior material with excellent electrolyte resistance, preventing peeling of the base layer 1 even when electrolyte adheres to the side surface.

In addition, the adhesive layer 2 may contain other components as long as they do not impair adhesion, such as colorants, thermoplastic elastomers, tackifiers, and fillers. By including a colorant in the adhesive layer 2, the electrical storage device packaging material can be colored. Known colorants such as pigments and dyes can be used. A single colorant may be used, or two or more colorants may be mixed together.

There are no particular restrictions on the type of pigment, so long as it does not impair the adhesive properties of the adhesive layer 2. Examples of organic pigments include azo, phthalocyanine, quinacridone, anthraquinone, dioxazine, indigothioindigo, perinone-perylene, isoindolenine, and benzimidazolone pigments. Examples of inorganic pigments include carbon black, titanium oxide, cadmium, lead, chromium oxide, iron, and copper pigments. Other examples include finely powdered mica and fish scale foil. Pigments can be used alone or in combination, such as a mixture of organic and inorganic pigments.

Among colorants, carbon black is preferred, for example, to give the exterior material for an electrical storage device a black appearance.

The average particle size of the pigment is not particularly limited, but may be, for example, approximately 0.05 to 5 μm, and preferably approximately 0.08 to 2 μm. The average particle size of the pigment is the median diameter measured using a laser diffraction/scattering particle size distribution analyzer.

The pigment content in the adhesive layer 2 is not particularly limited as long as it colors the electrical storage device exterior material, but may be, for example, approximately 5 to 60% by mass, and preferably 8 to 40% by mass.

There are no particular restrictions on the thickness of the adhesive layer 2, as long as it can bond the base layer 1 and the barrier layer 3 together. However, the lower limit can be, for example, approximately 1 μm or more, or approximately 2 μm or more, and the upper limit can be approximately 10 μm or less, or approximately 5 μm or less. Preferred ranges include approximately 1 to 10 μm, approximately 1 to 5 μm, approximately 2 to 10 μm, and approximately 2 to 5 μm.

[Colored layer]
The colored layer is a layer (not shown) that is provided as needed between the base material layer 1 and the barrier layer 3. When the adhesive layer 2 is provided, a colored layer may be provided between the base material layer 1 and the adhesive layer 2, or between the adhesive layer 2 and the barrier layer 3. Alternatively, a colored layer may be provided on the outside of the base material layer 1. By providing a colored layer, the packaging material for an electricity storage device can be colored.

The colored layer can be formed, for example, by applying ink containing a colorant to the surface of the base layer 1, the surface of the adhesive layer 2, or the surface of the barrier layer 3. Known colorants such as pigments and dyes can be used as colorants. Furthermore, a single type of colorant may be used, or two or more types may be mixed together.

Specific examples of colorants contained in the colored layer include the same as those exemplified in the [Adhesive Layer 2] section.

[Barrier layer 3]
In the packaging material for an electricity storage device, the barrier layer 3 is a layer that at least prevents the penetration of moisture.

Examples of the barrier layer 3 include metal foils, vapor-deposited films, and resin layers with barrier properties. Vapor-deposited films include metal vapor-deposited films, inorganic oxide vapor-deposited films, and carbon-containing inorganic oxide vapor-deposited films. Resin layers include fluorine-containing resins such as polyvinylidene chloride, polymers based on chlorotrifluoroethylene (CTFE), polymers based on tetrafluoroethylene (TFE), polymers containing fluoroalkyl groups, and polymers based on fluoroalkyl units, as well as ethylene-vinyl alcohol copolymers. Examples of the barrier layer 3 also include resin films comprising at least one of these vapor-deposited films and resin layers. The barrier layer 3 may comprise multiple layers. The barrier layer 3 preferably includes a layer composed of a metal material. Specific examples of metal materials that make up the barrier layer 3 include aluminum alloys, stainless steel, titanium steel, and steel plates. When used as a metal foil, the barrier layer 3 preferably includes at least one of aluminum alloy foil and stainless steel foil.

From the viewpoint of improving the formability of the electrical storage device exterior material, the aluminum alloy foil is preferably a soft aluminum alloy foil made of, for example, an annealed aluminum alloy, and from the viewpoint of further improving formability, it is preferably an iron-containing aluminum alloy foil. In the iron-containing aluminum alloy foil (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. By having an iron content of 0.1% by mass or more, an electrical storage device exterior material with better formability can be obtained. By having an iron content of 9.0% by mass or less, an electrical storage device exterior material with better flexibility can be obtained. Examples of soft aluminum alloy foils include aluminum alloy foils having compositions specified in JIS H4160:1994 A8021H-O, JIS H4160:1994 A8079H-O, JIS H4000:2014 A8021P-O, or JIS H4000:2014 A8079P-O. Silicon, magnesium, copper, manganese, etc. may also be added as needed. Softening can be achieved by annealing or other methods.

Furthermore, examples of stainless steel foil include austenitic, ferritic, austenitic-ferritic, martensitic, and precipitation-hardened stainless steel foils. Furthermore, from the perspective of providing an exterior material for an electricity storage device with excellent formability, it is preferable that the stainless steel foil be made of austenitic stainless steel.

Specific examples of austenitic stainless steels that make up the stainless steel foil include SUS304, SUS301, and SUS316L, with SUS304 being particularly preferred.

In the case of metal foil, the thickness of the barrier layer 3 should be such that it at least functions as a barrier layer to prevent moisture penetration, and can be, for example, approximately 9 to 200 μm. The upper limit of the thickness of the barrier layer 3 is preferably about 85 μm or less, more preferably about 50 μm or less, even more preferably about 40 μm or less, and particularly preferably about 35 μm or less, and the lower limit is preferably about 10 μm or more, even more preferably about 20 μm or more, and more preferably about 25 μm or more. Preferred thickness ranges include about 10 to 85 μm, about 10 to 50 μm, about 10 to 40 μm, about 10 to 35 μm, about 20 to 85 μm, about 20 to 50 μm, about 20 to 40 μm, about 20 to 35 μm, about 25 to 85 μm, about 25 to 50 μm, about 25 to 40 μm, and about 25 to 35 μm, with about 25 to 40 μm being particularly preferred. When the barrier layer 3 is made of aluminum alloy foil, the above-mentioned ranges are particularly preferred. Furthermore, particularly when the barrier layer 3 is composed of stainless steel foil, the upper limit of the thickness of the stainless steel foil is preferably about 60 μm or less, more preferably about 50 μm or less, even more preferably about 40 μm or less, even more preferably about 30 μm or less, and particularly preferably about 25 μm or less. The lower limit is preferably about 10 μm or more, more preferably about 15 μm or more. Preferred thickness ranges include approximately 10 to 60 μm, approximately 10 to 50 μm, approximately 10 to 40 μm, approximately 10 to 30 μm, approximately 10 to 25 μm, approximately 15 to 60 μm, approximately 15 to 50 μm, approximately 15 to 40 μm, approximately 15 to 30 μm, and approximately 15 to 25 μm.

Furthermore, when the barrier layer 3 is a metal foil, it is preferable that at least the surface opposite the substrate layer be provided with a corrosion-resistant coating to prevent dissolution and corrosion. The barrier layer 3 may be provided with a corrosion-resistant coating on both sides. Here, a corrosion-resistant coating refers to a thin film formed on the surface of the barrier layer that is corrosion-resistant, and is obtained by, for example, hydrothermal conversion treatment such as boehmite treatment, chemical conversion treatment, anodizing treatment, plating treatment with nickel or chromium, or corrosion prevention treatment such as applying a coating agent. A single type of treatment may be used to form the corrosion-resistant coating, or two or more types may be combined. Furthermore, multiple layers may be formed, rather than a single layer. Furthermore, among these treatments, hydrothermal conversion treatment and anodizing treatment dissolve the metal foil surface with a treatment agent to form a metal compound with excellent corrosion resistance. Note that these treatments may also be included in the definition of chemical conversion treatment. Furthermore, when the barrier layer 3 has a corrosion-resistant coating, the corrosion-resistant coating is also included in the barrier layer 3.

The corrosion-resistant coating prevents delamination between the barrier layer (e.g., aluminum alloy foil) and the substrate layer during molding of the electrical storage device exterior material, prevents dissolution and corrosion of the barrier layer surface due to hydrogen fluoride produced by the reaction between the electrolyte and water, and particularly prevents dissolution and corrosion of aluminum oxide present on the barrier layer surface when the barrier layer is aluminum alloy foil, and also improves the adhesion (wettability) of the barrier layer surface, preventing delamination between the substrate layer and barrier layer during heat sealing and molding.

Various corrosion-resistant coatings formed by chemical conversion treatments are known, including those containing at least one of phosphates, chromates, fluorides, triazine thiol compounds, and rare earth oxides. Examples of chemical conversion treatments using phosphates and chromates include chromate chromate treatment, phosphate chromate treatment, phosphate-chromate treatment, and chromate treatment. Chromium compounds used in these treatments include chromium nitrate, chromium fluoride, chromium sulfate, chromium acetate, chromium oxalate, chromium biphosphate, chromate acetylacetate, chromium chloride, and potassium chromium sulfate. Phosphorus compounds used in these treatments include sodium phosphate, potassium phosphate, ammonium phosphate, and polyphosphoric acid. Chromate treatments include etching chromate treatment, electrolytic chromate treatment, and paint-on chromate treatment, with paint-on chromate treatment being preferred. This paint-type chromate treatment involves first degreasing at least the inner surface of a barrier layer (e.g., an aluminum alloy foil) using a well-known method such as alkali immersion, electrolytic cleaning, acid pickling, electrolytic pickling, or acid activation, and then coating the degreased surface with a treatment solution containing, as its main component, a metal phosphate such as chromium (Cr) phosphate, titanium (Ti) phosphate, zirconium (Zr) phosphate, or zinc (Zn) phosphate, or a mixture of these metal salts, or a treatment solution containing, as its main component, a nonmetallic phosphate and a mixture of these nonmetallic salts, or a mixture of these with a synthetic resin, by a well-known coating method such as roll coating, gravure printing, or immersion, followed by drying. The treatment solution can be, for example, water, alcoholic solvents, hydrocarbon solvents, ketone solvents, ester solvents, or ether solvents, with water being preferred. The resin component used here may include polymers such as phenolic resins and acrylic resins, and examples thereof include chromate treatment using an aminated phenolic polymer having repeating units represented by the following general formulas (1) to (4). The aminated phenolic polymer may contain one repeating unit represented by the following general formulas (1) to (4) alone, or any combination of two or more repeating units. The acrylic resin is preferably polyacrylic acid, an acrylic acid-methacrylic acid ester copolymer, an acrylic acid-maleic acid copolymer, an acrylic acid-styrene copolymer, or a derivative thereof, such as a sodium salt, an ammonium salt, or an amine salt. Derivatives of polyacrylic acid, such as the ammonium salt, sodium salt, or amine salt of polyacrylic acid, are particularly preferred. In this disclosure, polyacrylic acid refers to a polymer of acrylic acid. The acrylic resin is also preferably a copolymer of acrylic acid and a dicarboxylic acid or a dicarboxylic acid anhydride, and preferably an ammonium salt, a sodium salt, or an amine salt of a copolymer of acrylic acid and a dicarboxylic acid or a dicarboxylic acid anhydride. Only one type of acrylic resin may be used, or two or more types may be mixed together.

In general formulas (1) to (4), X represents a hydrogen atom, a hydroxy group, an alkyl group, a hydroxyalkyl group, an allyl group, or a benzyl group. ^R1 and ^R2 , which may be the same or different, represent a hydroxy group, an alkyl group, or a hydroxyalkyl group. In general formulas (1) to (4), examples of the alkyl group represented by X, ^R1 , and ^R2 include linear or branched alkyl groups having 1 to 4 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, and a tert-butyl group. Examples of the hydroxyalkyl group represented by X, ^R1 , and ^R2 include linear or branched alkyl groups having 1 to 4 carbon atoms and substituted with one hydroxy group, such as a hydroxymethyl group, a 1-hydroxyethyl group, a 2-hydroxyethyl group, a 1-hydroxypropyl group, a 2-hydroxypropyl group, a 3-hydroxypropyl group, a 1-hydroxybutyl group, a 2-hydroxybutyl group, a 3-hydroxybutyl group, and a 4-hydroxybutyl group. In general formulas (1) to (4), the alkyl groups and hydroxyalkyl groups represented by X, ^R1 , and ^R2 may be the same or different. In general formulas (1) to (4), X is preferably a hydrogen atom, a hydroxy group, or a hydroxyalkyl group. The number-average molecular weight of the aminated phenol polymer having repeating units represented by general formulas (1) to (4) is preferably, for example, about 500 to 1,000,000, and more preferably about 1,000 to 20,000. The aminated phenol polymer can be produced, for example, by polycondensing a phenol compound or a naphthol compound with formaldehyde to produce a polymer comprising repeating units represented by general formula ( ₁ ) or ^{(3), and then introducing a functional group (—CH2NR1R2) into the resulting polymer using formaldehyde and an amine (R1R2NH ) . The} aminated phenol polymer may be used alone or in combination of two or more types.

Other examples of corrosion-resistant coatings include thin films formed by a coating-type corrosion prevention treatment in which a coating agent containing at least one selected from the group consisting of rare earth element oxide sol, anionic polymer, and cationic polymer is applied. The coating agent may further contain phosphoric acid or phosphate salts, and a crosslinking agent for crosslinking the polymer. The rare earth element oxide sol contains rare earth element oxide fine particles (e.g., particles with an average particle size of 100 nm or less) dispersed in a liquid dispersion medium. Examples of rare earth element oxides include cerium oxide, yttrium oxide, neodymium oxide, and lanthanum oxide, with cerium oxide being preferred for improved adhesion. The rare earth element oxides contained in the corrosion-resistant coating can be used alone or in combination of two or more. Liquid dispersion media for the rare earth element oxide sol can include various solvents, such as water, alcohol-based solvents, hydrocarbon-based solvents, ketone-based solvents, ester-based solvents, and ether-based solvents, with water being preferred. Preferred examples of cationic polymers include polyethyleneimine, ionic polymer complexes consisting of polyethyleneimine and a polymer having a carboxylic acid, primary amine-grafted acrylic resins in which a primary amine is graft-polymerized onto an acrylic backbone, polyallylamine or its derivatives, and aminated phenols. Preferred anionic polymers are poly(meth)acrylic acid or its salts, or copolymers primarily composed of (meth)acrylic acid or its salts. The crosslinking agent is preferably at least one selected from the group consisting of compounds having a functional group selected from isocyanate, glycidyl, carboxyl, and oxazoline groups, and silane coupling agents. The phosphoric acid or phosphoric acid salt is preferably condensed phosphoric acid or a condensed phosphate salt.

One example of a corrosion-resistant coating is one formed by applying a solution of fine particles of metal oxides such as aluminum oxide, titanium oxide, cerium oxide, and tin oxide, or barium sulfate dispersed in phosphoric acid to the surface of the barrier layer and then baking it at 150°C or higher.

If necessary, the corrosion-resistant coating may have a laminated structure in which at least one of a cationic polymer and an anionic polymer is further laminated. Examples of cationic polymers and anionic polymers include those described above.

The composition of the corrosion-resistant coating can be analyzed using, for example, time-of-flight secondary ion mass spectrometry.

The amount of the corrosion-resistant film formed on the surface of the barrier layer 3 in the chemical conversion treatment is not particularly limited. For example, when a coating type chromate treatment is performed, the amount of the chromate compound is, for example, about 0.5 to 50 mg, preferably 1 mg, in terms of chromium, per 1 m ² of the surface of the barrier layer 3.
It is desirable that the content of the phosphorus compound is, for example, about 0.5 to 50 mg, preferably about 1.0 to 40 mg, in terms of phosphorus, and the content of the aminated phenol polymer is, for example, about 1.0 to 200 mg, preferably about 5.0 to 150 mg.

The thickness of the corrosion-resistant coating is not particularly limited, but is preferably about 1 nm to 20 μm, more preferably about 1 nm to 100 nm, and even more preferably about 1 nm to 50 nm, from the viewpoint of the cohesive strength of the coating and the adhesive strength with the barrier layer and the thermally adhesive resin layer. The thickness of the corrosion-resistant coating can be measured by observation with a transmission electron microscope, or by a combination of observation with a transmission electron microscope and energy dispersive X-ray spectroscopy or electron energy loss spectroscopy. Analysis of the composition of the corrosion-resistant coating using time-of-flight secondary ion mass spectrometry can reveal, for example, secondary ions consisting of Ce, P, and O (e.g., Ce ₂ PO ₄ ⁺ , C
Peaks derived from secondary ions composed of Cr, P, and O (for example, at least one of CrPO 2 + , CrPO ₄ ⁻ , etc.) and secondary ions composed of Cr, P, and O (for example, at least one of CrPO ₂ ⁺ , CrPO ₄ ^{− ,} etc.) are detected.

Chemical conversion treatment is performed by applying a solution containing the compound used to form the corrosion-resistant coating to the surface of the barrier layer using methods such as bar coating, roll coating, gravure coating, or immersion, and then heating the barrier layer to a temperature of approximately 70 to 200°C. Furthermore, before applying chemical conversion treatment to the barrier layer, the barrier layer may be subjected to a degreasing treatment using methods such as alkaline immersion, electrolytic cleaning, acid cleaning, or electrolytic acid cleaning. Performing such a degreasing treatment allows for more efficient chemical conversion treatment of the barrier layer surface. Furthermore, using an acid degreasing agent in which a fluorine-containing compound is dissolved in an inorganic acid not only degreases the metal foil but also forms a passive metal fluoride. In such cases, it is possible to perform only the degreasing treatment.

[Thermofusible resin layer 4]
In the exterior packaging material for an electricity storage device of the present disclosure, the heat-sealable resin layer 4 corresponds to the innermost layer and is a layer (sealant layer) that functions to seal the electricity storage device elements by heat-sealing the heat-sealable resin layers to each other when assembling the electricity storage device.

The resin constituting the heat-sealable resin layer 4 is not particularly limited as long as it is heat-sealable, but resins containing a polyolefin skeleton, such as polyolefins and acid-modified polyolefins, are preferred. The polyolefin skeleton of the resin constituting the heat-sealable resin layer 4 can be determined by, for example, infrared spectroscopy or gas chromatography-mass spectrometry. Furthermore, when the resin constituting the heat-sealable resin layer 4 is analyzed by infrared spectroscopy, peaks derived from maleic anhydride are preferably detected. For example, when measuring maleic anhydride-modified polyolefin by infrared spectroscopy, peaks derived from maleic anhydride are detected near wavenumbers 1760 cm ⁻¹ and 1780 cm ⁻¹ . When the heat-sealable resin layer 4 is a layer composed of maleic anhydride-modified polyolefin, peaks derived from maleic anhydride are detected by infrared spectroscopy. However, if the degree of acid modification is low, the peaks may be small and not be detected. In such cases, analysis can be performed by nuclear magnetic resonance spectroscopy.

Specific examples of polyolefins include polyethylenes such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; ethylene-α-olefin copolymers; polypropylenes such as homopolypropylene, block copolymers of polypropylene (e.g., block copolymers of propylene and ethylene), and random copolymers of polypropylene (e.g., random copolymers of propylene and ethylene); propylene-α-olefin copolymers; and ethylene-butene-propylene terpolymers. Of these, polypropylene is preferred. When the polyolefin resin is a copolymer, it may be a block copolymer or a random copolymer. These polyolefin resins may be used alone or in combination of two or more.

The polyolefin may also be a cyclic polyolefin. Cyclic polyolefins are copolymers of olefins and cyclic monomers. Examples of olefins that constitute the cyclic polyolefin include ethylene, propylene, 4-methyl-1-pentene, styrene, butadiene, and isoprene. Examples of cyclic monomers that constitute the cyclic polyolefin include cyclic alkenes such as norbornene; and cyclic dienes such as cyclopentadiene, dicyclopentadiene, cyclohexadiene, and norbornadiene. Among these, cyclic alkenes are preferred, and norbornene is even more preferred.

Acid-modified polyolefins are polymers modified by block or graft polymerization of polyolefins with an acid component. Examples of acid-modified polyolefins include the polyolefins listed above, copolymers of the polyolefins with polar molecules such as acrylic acid or methacrylic acid, and cross-linked polyolefins. Examples of acid components used for acid modification include carboxylic acids or anhydrides such as maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, and itaconic anhydride.

The acid-modified polyolefin may be an acid-modified cyclic polyolefin. The acid-modified cyclic polyolefin is a polymer obtained by copolymerizing a part of the monomers constituting the cyclic polyolefin by replacing it with an acid component, or by block polymerizing or graft polymerizing an acid component onto the cyclic polyolefin. The acid-modified cyclic polyolefin is the same as described above. The acid component used for the acid modification is the same as the acid component used for the modification of the polyolefin.

Preferred acid-modified polyolefins include polyolefins modified with carboxylic acids or their anhydrides, polypropylenes modified with carboxylic acids or their anhydrides, maleic anhydride-modified polyolefins, and maleic anhydride-modified polypropylenes.

The heat-sealable resin layer 4 may be formed from a single type of resin, or may be formed from a blend polymer of two or more types of resin. Furthermore, the heat-sealable resin layer 4 may be formed from only one layer, or may be formed from two or more layers of the same or different resins.

The heat-sealable resin layer 4 may also contain a lubricant, if necessary. When the heat-sealable resin layer 4 contains a lubricant, the formability of the electrical storage device packaging material can be improved. There are no particular restrictions on the lubricant, and any known lubricant can be used. The lubricant may be used alone or in combination of two or more types.

The lubricant is not particularly limited, but preferably an amide-based lubricant is used. Specific examples of lubricants include those exemplified for base layer 1. One type of lubricant may be used alone, or two or more types may be used in combination.

When a lubricant is present on the surface of the heat-fusible resin layer 4, the amount thereof is not particularly limited, but from the viewpoint of improving the formability of the exterior material for an electricity storage device, it is preferably about 10 to 50 mg/ ^m2 , and more preferably about 15 to 40 mg/ ^m2 .

The lubricant present on the surface of the heat-sealable resin layer 4 may be a lubricant exuded from the resin that makes up the heat-sealable resin layer 4, or a lubricant applied to the surface of the heat-sealable resin layer 4.

The thickness of the heat-sealable resin layer 4 is not particularly limited as long as it functions to heat-seal the heat-sealable resin layers together and seal the electricity storage device element, but examples include approximately 100 μm or less, preferably approximately 85 μm or less, and more preferably approximately 15 to 85 μm. For example, if the thickness of the adhesive layer 5 described below is 10 μm or greater, the thickness of the heat-sealable resin layer 4 is preferably approximately 85 μm or less, more preferably approximately 15 to 45 μm. For example, if the thickness of the adhesive layer 5 described below is less than 10 μm or if the adhesive layer 5 is not provided, the thickness of the heat-sealable resin layer 4 is preferably approximately 20 μm or greater, more preferably approximately 35 to 85 μm.

[Adhesive layer 5]
In the packaging material for an electricity storage device of the present disclosure, the adhesive layer 5 is a layer that is provided as needed between the barrier layer 3 (or the corrosion-resistant coating) and the heat-sealable resin layer 4 in order to firmly bond them together.

The adhesive layer 5 is formed of a resin capable of bonding the barrier layer 3 and the heat-sealable resin layer 4. Examples of resins used to form the adhesive layer 5 include the same adhesives as those exemplified for the adhesive layer 2. The resin used to form the adhesive layer 5 preferably contains a polyolefin skeleton, such as the polyolefins and acid-modified polyolefins exemplified for the heat-sealable resin layer 4. The presence of a polyolefin skeleton in the resin constituting the adhesive layer 5 can be determined by, for example, infrared spectroscopy or gas chromatography-mass spectrometry; any analytical method is acceptable. Furthermore, when the resin constituting the adhesive layer 5 is analyzed by infrared spectroscopy, peaks derived from maleic anhydride are preferably detected. For example, when a maleic anhydride-modified polyolefin is measured by infrared spectroscopy, peaks derived from maleic anhydride are detected near wavenumbers 1760 cm ⁻¹ and 1780 cm ⁻¹ . However, if the degree of acid modification is low, the peaks may be small and not be detected. In such cases, analysis by nuclear magnetic resonance spectroscopy is possible.

From the viewpoint of firmly adhering the barrier layer 3 and the heat-sealable resin layer 4, the adhesive layer 5 preferably contains an acid-modified polyolefin. Particularly preferred acid-modified polyolefins are polyolefins modified with carboxylic acids or their anhydrides, polypropylenes modified with carboxylic acids or their anhydrides, maleic anhydride-modified polyolefins, and maleic anhydride-modified polypropylenes.

Furthermore, from the viewpoint of reducing the thickness of the electrical storage device exterior material while providing an electrical storage device exterior material with excellent shape stability after molding, it is more preferable that the adhesive layer 5 be a cured product of a resin composition containing an acid-modified polyolefin and a curing agent. Preferred examples of acid-modified polyolefins include those listed above.

Furthermore, the adhesive layer 5 is preferably a cured product of a resin composition containing an acid-modified polyolefin and at least one compound selected from the group consisting of a compound having an isocyanate group, a compound having an oxazoline group, and a compound having an epoxy group. It is particularly preferably a cured product of a resin composition containing an acid-modified polyolefin and at least one compound selected from the group consisting of a compound having an isocyanate group and a compound having an epoxy group. The adhesive layer 5 preferably contains at least one compound selected from the group consisting of polyurethane, polyester, and epoxy resin, and more preferably contains polyurethane and epoxy resin. A preferred polyester is, for example, an amide ester resin. Amide ester resins are generally produced by the reaction of a carboxyl group and an oxazoline group. It is more preferred that the adhesive layer 5 is a cured product of a resin composition containing at least one of these resins and the acid-modified polyolefin. Furthermore, if unreacted compounds of curing agents such as compounds having an isocyanate group, compounds having an oxazoline group, or epoxy resin remain in the adhesive layer 5, the presence of the unreacted compounds can be confirmed by a method selected from the group consisting of infrared spectroscopy, Raman spectroscopy, and time-of-flight secondary ion mass spectrometry (TOF-SIMS).

In order to further enhance the adhesion between the barrier layer 3 and the adhesive layer 5, the adhesive layer 5 is preferably a cured product of a resin composition containing a curing agent having at least one selected from the group consisting of an oxygen atom, a heterocycle, a C=N bond, and a C-O-C bond. Examples of curing agents having a heterocycle include curing agents having an oxazoline group and curing agents having an epoxy group. Examples of curing agents having a C=N bond include curing agents having an oxazoline group and curing agents having an isocyanate group. Examples of curing agents having a C-O-C bond include curing agents having an oxazoline group, curing agents having an epoxy group, and polyurethane. Whether the adhesive layer 5 is a cured product of a resin composition containing such a curing agent can be confirmed by, for example, gas chromatography mass spectrometry (GCMS), infrared spectroscopy (IR), time-of-flight secondary ion mass spectrometry (TOF-SIMS), X-ray photoelectron spectroscopy (XPS), or other methods.

The compound having an isocyanate group is not particularly limited, but from the viewpoint of effectively enhancing adhesion between the barrier layer 3 and the adhesive layer 5, a polyfunctional isocyanate compound is preferable. The polyfunctional isocyanate compound is not particularly limited as long as it has two or more isocyanate groups. Specific examples of polyfunctional isocyanate curing agents include pentane diisocyanate (PDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), polymers or nurates thereof, mixtures of these, and copolymers with other polymers. Other examples include adducts, biuret compounds, and isocyanurates.

The content of the compound having an isocyanate group in the adhesive layer 5 is preferably in the range of 0.1 to 50% by mass, and more preferably in the range of 0.5 to 40% by mass, of the resin composition that constitutes the adhesive layer 5. This effectively improves the adhesion between the barrier layer 3 and the adhesive layer 5.

The compound having an oxazoline group is not particularly limited as long as it has an oxazoline skeleton. Specific examples of compounds having an oxazoline group include those having a polystyrene main chain and those having an acrylic main chain. Commercially available products include the Epocross series manufactured by Nippon Shokubai Co., Ltd.

The proportion of the compound having an oxazoline group in the adhesive layer 5 is preferably in the range of 0.1 to 50 mass %, and more preferably in the range of 0.5 to 40 mass %, of the resin composition that constitutes the adhesive layer 5. This effectively improves the adhesion between the barrier layer 3 and the adhesive layer 5.

An example of a compound having an epoxy group is an epoxy resin. There are no particular restrictions on the epoxy resin, so long as it is a resin capable of forming a crosslinked structure via the epoxy groups present in the molecule, and known epoxy resins can be used. The weight-average molecular weight of the epoxy resin is preferably approximately 50 to 2,000, more preferably approximately 100 to 1,000, and even more preferably approximately 200 to 800. In the first disclosure, the weight-average molecular weight of the epoxy resin is a value measured by gel permeation chromatography (GPC) under conditions using polystyrene as a standard sample.

Specific examples of epoxy resins include glycidyl ether derivatives of trimethylolpropane, bisphenol A diglycidyl ether, modified bisphenol A diglycidyl ether, novolac glycidyl ether, glycerin polyglycidyl ether, and polyglycerin polyglycidyl ether. Epoxy resins may be used alone or in combination of two or more.

The proportion of epoxy resin in adhesive layer 5 is preferably in the range of 0.1 to 50% by mass, and more preferably in the range of 0.5 to 40% by mass, of the resin composition that makes up adhesive layer 5. This effectively improves the adhesion between barrier layer 3 and adhesive layer 5.

The polyurethane is not particularly limited, and any known polyurethane can be used. The adhesive layer 5 may be, for example, a cured product of a two-component curing polyurethane.

The proportion of polyurethane in adhesive layer 5 is preferably in the range of 0.1 to 50 mass % of the resin composition constituting adhesive layer 5, and more preferably in the range of 0.5 to 40 mass %. This effectively improves adhesion between barrier layer 3 and adhesive layer 5 in an atmosphere containing components that induce corrosion of the barrier layer, such as electrolyte solution.

When adhesive layer 5 is a cured product of a resin composition containing at least one selected from the group consisting of a compound having an isocyanate group, a compound having an oxazoline group, and an epoxy resin, and the acid-modified polyolefin, the acid-modified polyolefin functions as the base resin, and the compound having an isocyanate group, the compound having an oxazoline group, and the compound having an epoxy group each function as a curing agent.

The upper limit of the thickness of adhesive layer 5 is preferably approximately 50 μm or less, approximately 40 μm or less, approximately 30 μm or less, approximately 20 μm or less, or approximately 5 μm or less. The lower limit is preferably approximately 0.1 μm or more, or approximately 0.5 μm or more. The thickness range is preferably approximately 0.1 to 50 μm, approximately 0.1 to 40 μm, approximately 0.1 to 30 μm, approximately 0.1 to 20 μm, approximately 0.1 to 5 μm, approximately 0.5 to 50 μm, approximately 0.5 to 40 μm, approximately 0.5 to 30 μm, approximately 0.5 to 20 μm, or approximately 0.5 to 5 μm. More specifically, in the case of adhesives such as those exemplified for adhesive layer 2 or a cured product of an acid-modified polyolefin and a curing agent, the thickness is preferably approximately 1 to 10 μm, more preferably approximately 1 to 5 μm. Furthermore, when using a resin exemplified for the heat-sealable resin layer 4, the thickness is preferably about 2 to 50 μm, and more preferably about 10 to 40 μm. When the adhesive layer 5 is an adhesive exemplified for the adhesive layer 2, or a cured product of a resin composition containing an acid-modified polyolefin and a curing agent, the adhesive layer 5 can be formed, for example, by applying the resin composition and curing it by heating or the like. When using a resin exemplified for the heat-sealable resin layer 4, the heat-sealable resin layer 4 and the adhesive layer 5 can be formed, for example, by extrusion molding.

[Surface coating layer 6]
The packaging material for an electricity storage device according to the present disclosure may, if necessary, have a surface coating layer 6 on the substrate layer 1 (the side of the substrate layer 1 opposite to the barrier layer 3) for the purpose of improving at least one of design, electrolyte resistance, scratch resistance, formability, etc. The surface coating layer 6 is a layer located on the outermost layer side of the packaging material for an electricity storage device when an electricity storage device is assembled using the packaging material for an electricity storage device.

The surface coating layer 6 can be formed from a resin such as polyvinylidene chloride, polyester, polyurethane, acrylic resin, or epoxy resin.

When the resin forming the surface coating layer 6 is a curable resin, the resin may be either a one-component curable resin or a two-component curable resin, but is preferably a two-component curable resin. Examples of two-component curable resins include two-component curable polyurethane, two-component curable polyester, and two-component curable epoxy resin. Of these, two-component curable polyurethane is preferred.

Examples of two-component curing polyurethanes include polyurethanes containing a base agent containing a polyol compound and a curing agent containing an isocyanate compound. Preferred examples include two-component curing polyurethanes that use a polyol such as polyester polyol, polyether polyol, or acrylic polyol as the base agent and an aromatic or aliphatic polyisocyanate as the curing agent. Furthermore, it is preferable to use a polyester polyol that has hydroxyl groups on the side chain in addition to the terminal hydroxyl groups of the repeating unit as the polyol compound. Forming the surface coating layer 6 from polyurethane provides the electrical storage device exterior material with excellent electrolyte resistance.

The surface coating layer 6 may contain additives such as the aforementioned lubricants, antiblocking agents, matting agents, flame retardants, antioxidants, tackifiers, and antistatic agents, at least on the surface and/or inside the surface coating layer 6, as needed, depending on the functionality to be provided by the surface coating layer 6 and its surface. Examples of additives include fine particles with an average particle size of approximately 0.5 nm to 5 μm. The average particle size of the additive is the median size measured using a laser diffraction/scattering particle size distribution analyzer.

Additives may be either inorganic or organic. There are also no particular restrictions on the shape of the additive, and examples include spherical, fibrous, plate-like, irregular, and scaly shapes.

Specific examples of additives include talc, silica, graphite, kaolin, montmorillonite, mica, hydrotalcite, silica gel, zeolite, aluminum hydroxide, magnesium hydroxide, zinc oxide, magnesium oxide, aluminum oxide, neodymium oxide, antimony oxide, titanium oxide, cerium oxide, calcium sulfate, barium sulfate, calcium carbonate, calcium silicate, lithium carbonate, calcium benzoate, calcium oxalate, magnesium stearate, alumina, carbon black, carbon nanotubes, high-melting-point nylon, acrylate resin, cross-linked acrylic, cross-linked styrene, cross-linked polyethylene, benzoguanamine, gold, aluminum, copper, and nickel. Additives may be used alone or in combination of two or more. Among these additives, silica, barium sulfate, and titanium oxide are preferred from the standpoints of dispersion stability and cost. The additives may also be subjected to various surface treatments, such as insulation treatments and high-dispersion treatments.

The method for forming the surface coating layer 6 is not particularly limited, and examples include a method of applying a resin to form the surface coating layer 6. If an additive is to be blended into the surface coating layer 6, a resin mixed with the additive may be applied.

The thickness of the surface coating layer 6 is not particularly limited as long as it exhibits the above-mentioned functions of the surface coating layer 6, but may be, for example, approximately 0.5 to 10 μm, and preferably approximately 1 to 5 μm.

3. Manufacturing Method of Electricity Storage Device Exterior Material The manufacturing method of the electricity storage device exterior material is not particularly limited as long as it can obtain a laminate in which each layer included in the electricity storage device exterior material of the present disclosure is laminated, and examples include a method comprising a step of laminating, in this order from the outside, at least a substrate layer 1, a barrier layer 3, and a heat-sealable resin layer 4. Specifically, the manufacturing method of the electricity storage device exterior material of the present disclosure comprises a step of obtaining a laminate in which, in this order from the outside, at least a substrate layer, a barrier layer, and a heat-sealable resin layer are laminated, the substrate layer includes a polyamide film, and the crystallization index of the polyamide film measured from the outside of the substrate layer by the ATR method of Fourier transform infrared spectroscopy is 1.50 or more.

An example of a manufacturing method for an exterior material for an electricity storage device according to the present disclosure is as follows. First, a laminate (hereinafter sometimes referred to as "laminate A") is formed in which a substrate layer 1, an adhesive layer 2, and a barrier layer 3 are laminated in this order. Specifically, laminate A can be formed by a dry lamination method in which the adhesive used to form adhesive layer 2 is applied to substrate layer 1 or, if necessary, to barrier layer 3 whose surface has been chemically treated, by a coating method such as gravure coating or roll coating, and then dried. After that, the barrier layer 3 or substrate layer 1 is laminated, and the adhesive layer 2 is cured.

Next, a heat-sealable resin layer 4 is laminated on the barrier layer 3 of the laminate A. When the heat-sealable resin layer 4 is laminated directly on the barrier layer 3, the heat-sealable resin layer 4 may be laminated on the barrier layer 3 of the laminate A by a method such as thermal lamination or extrusion lamination. Furthermore, when an adhesive layer 5 is provided between the barrier layer 3 and the heat-sealable resin layer 4, for example, (1) a method of laminating the adhesive layer 5 and the heat-sealable resin layer 4 by extruding them onto the barrier layer 3 of the laminate A (co-extrusion lamination, tandem lamination), (2) a method of separately forming a laminate in which the adhesive layer 5 and the heat-sealable resin layer 4 are laminated, and then laminating this on the barrier layer 3 of the laminate A by a thermal lamination, or a method of forming a laminate in which the adhesive layer 5 is laminated on the barrier layer 3 of the laminate A, and then laminating this with the heat-sealable resin layer 4 by a thermal lamination, (3) a method (sandwich lamination method) in which a molten adhesive layer 5 is poured between the barrier layer 3 of the laminate A and a heat-sealable resin layer 4 that has been pre-formed into a sheet, and the laminate A and the heat-sealable resin layer 4 are bonded together via the adhesive layer 5; (4) a method in which an adhesive for forming the adhesive layer 5 is solution-coated onto the barrier layer 3 of the laminate A, followed by drying or baking, and then the heat-sealable resin layer 4 that has been pre-formed into a sheet is laminated onto this adhesive layer 5.

When the surface coating layer 6 is provided, the surface coating layer 6 is laminated on the surface of the base layer 1 opposite the barrier layer 3. The surface coating layer 6 can be formed, for example, by applying the above-mentioned resin that forms the surface coating layer 6 to the surface of the base layer 1. The order of the step of laminating the barrier layer 3 on the surface of the base layer 1 and the step of laminating the surface coating layer 6 on the surface of the base layer 1 is not particularly limited. For example, after the surface coating layer 6 is formed on the surface of the base layer 1, the barrier layer 3 may be formed on the surface of the base layer 1 opposite the surface coating layer 6.

As described above, a laminate is formed comprising, from the outside in, optional surface coating layer 6, substrate layer 1, optional adhesive layer 2, barrier layer 3, optional adhesive layer 5, and heat-sealable resin layer 4. To strengthen the adhesion of optional adhesive layer 2 and adhesive layer 5, the laminate may be further subjected to a heat treatment.

In the packaging material for an electricity storage device, each layer constituting the laminate may be subjected to a surface activation treatment such as corona treatment, blast treatment, oxidation treatment, or ozone treatment, as necessary, to improve its processability. For example, corona treatment can be performed on the surface of the base layer 1 opposite the barrier layer 3, thereby improving the printability of ink on the surface of the base layer 1.

The packaging material for an electricity storage device according to the present disclosure is used in a package for hermetically housing an electricity storage device element such as a positive electrode, a negative electrode, an electrolyte, etc. That is, an electricity storage device can be formed by housing an electricity storage device element including at least a positive electrode, a negative electrode, and an electrolyte in a package formed from the packaging material for an electricity storage device according to the present disclosure.

Specifically, an electricity storage device using the electricity storage device packaging material of the present disclosure is provided by covering an electricity storage device element having at least a positive electrode, a negative electrode, and an electrolyte with the electricity storage device packaging material of the present disclosure, with metal terminals connected to the positive electrode and negative electrode protruding outward, so that a flange portion (a region where the heat-sealable resin layers contact each other) is formed around the periphery of the electricity storage device element, and the heat-sealable resin layers of the flange portion are heat-sealed to form a hermetic seal. When an electricity storage device element is housed in a package formed from the electricity storage device packaging material of the present disclosure, the package is formed so that the heat-sealable resin portion of the electricity storage device packaging material of the present disclosure faces inward (the surface that contacts the electricity storage device element).

The exterior packaging material for an electricity storage device of the present disclosure can be suitably used for electricity storage devices such as batteries (including condensers, capacitors, etc.). The exterior packaging material for an electricity storage device of the present disclosure may be used for either primary or secondary batteries, but is preferably used for secondary batteries. The type of secondary battery to which the exterior packaging material for an electricity storage device of the present disclosure can be applied is not particularly limited, and examples include lithium ion batteries, lithium ion polymer batteries, all-solid-state batteries, lead-acid batteries, nickel-metal hydride batteries, nickel-cadmium batteries, nickel-iron batteries, nickel-zinc batteries, silver oxide-zinc batteries, metal-air batteries, polyvalent cation batteries, capacitors, and capacitors. Among these secondary batteries, lithium ion batteries and lithium ion polymer batteries are suitable applications for the exterior packaging material for an electricity storage device of the present disclosure.

Electricity storage devices are generally fixed to the housing of various products using double-sided tape or adhesive. That is, the exterior material 10 for an electricity storage device of the present disclosure is fixed to the housing of various products using double-sided tape or adhesive. The material of the housing varies depending on the type of product, and ranges widely, for example, from metals such as stainless steel, aluminum alloy, and nickel alloy, to plastics such as polyolefin, polyamide, polyester, polyimide, and polystyrene, and glass.

The adhesive strength between the electricity storage device and the housing is adjusted, for example, to a level that allows the electricity storage device to be peeled off from the housing. The peel strength between the electricity storage device and the housing is preferably fixed using double-sided tape that has a peel strength of approximately 5 to 15 N/7.5 mm against a stainless steel plate, as measured in the (Measuring Peel Strength of Double-Sided Tape) method described below. The exterior packaging material 10 for an electricity storage device can be suitably used for an electricity storage device that is fixed to a housing using double-sided tape that has a peel strength of approximately 5 to 15 N/7.5 mm against the housing.

5. Polyamide Film The polyamide film of the present disclosure is a polyamide film for use in the base layer of a packaging material for an electricity storage device, which is composed of a laminate including at least a base layer, a barrier layer, and a heat-sealable resin layer, and has a crystallization index of 1.50 or more as measured by the ATR method of Fourier transform infrared spectroscopy. Details of the packaging material for an electricity storage device 10 are as described above.

By using the polyamide film of the present disclosure as the substrate layer 1 of the electrical storage device exterior material, the crystallization index of the polyamide film of the substrate layer 1 of the electrical storage device exterior material 10 can be suitably set to 1.50 or greater, effectively preventing damage to the electrical storage device exterior material during the aforementioned peeling. That is, the electrical storage device exterior material 10 of the present disclosure is preferably manufactured by using the polyamide film of the present disclosure, whose crystallization index has been adjusted to 1.50 or greater, as the substrate layer 1 and laminating it with various layers, such as the barrier layer 3 and the heat-sealable resin layer 4. As described above, the crystallization index of the polyamide film laminated to the electrical storage device exterior material 10 and included in the substrate layer 1 can be made higher than that of the polyamide film before it is applied to the electrical storage device exterior material 10. Specifically, the crystallization index can also be increased by applying heat to the polyamide film during the manufacturing process of the electrical storage device exterior material 10.

The method for measuring the crystallization index for the polyamide film of the present disclosure is as follows:

<Measurement of Crystallization Index of Polyamide Film>
A polyamide film is cut into a 100 mm x 100 mm square to prepare a sample. The surface of the obtained sample is subjected to infrared absorption spectrum measurement using the ATR measurement mode of an FT-IR at a temperature of 25°C and a relative humidity of 50%. An example of the instrument that can be used is a Nicolet iS10 manufactured by Thermo Fisher Scientific. From the obtained absorption spectrum, a peak intensity P near 1200 cm ⁻¹ resulting from absorption of α-crystals of nylon and a peak intensity Q near 1370 cm ⁻¹ resulting from absorption unrelated to crystals are measured, and the intensity ratio X = P/Q of the peak intensity P to the peak intensity Q is calculated as the crystallization index.
(Measurement conditions)
Method: Macro ATR method Wavenumber resolution: 8cm ^-1
Number of integrations: 32 times Detector: DTGS detector ATR prism: Ge
Incident angle: 45°
Baseline: Obtained as a linear approximation between wave numbers 1100 cm ⁻¹ and 1400 cm ⁻¹ .
Absorption peak intensity Y ₁₂₀₀ : the value obtained by subtracting the baseline value from the maximum peak intensity in the wavenumber range of 1195 cm ⁻¹ to 1205 cm ⁻¹ Absorption peak intensity Y ₁₃₇₀ : the value obtained by subtracting the baseline value from the maximum peak intensity in the wavenumber range of 1365 cm ⁻¹ to 1375 cm ⁻¹

In the polyamide film of the present disclosure, the crystallization index may be 1.50 or greater. However, from the viewpoint of more effectively preventing damage to the electrical storage device packaging material during peeling, it is more preferably 1.55 or greater, even more preferably 1.60 or greater, and particularly preferably 1.65 or greater. The upper limit of the crystallization index is not particularly limited, but examples include 2.50 or less and 1.80 or less. Preferred ranges for the crystallization index include, for example, 1.50 to 2.50, 1.60 to 2.50, 1.65 to 2.50, 1.50 to 1.80, 1.60 to 1.80, and 1.65 to 1.80.

Specific examples of polyamides that form the polyamide film are as described in the section on the base material layer 1 of the electrical storage device exterior material 10. The polyamide film may be an unstretched film or a stretched film. Stretched films include uniaxially stretched films and biaxially stretched films, with biaxially stretched films being preferred. Stretching methods for forming biaxially stretched films include, for example, sequential biaxial stretching, inflation, and simultaneous biaxial stretching. Resin application methods include roll coating, gravure coating, and extrusion coating.

The polyamide film is preferably a biaxially oriented nylon film.

From the perspective of more effectively preventing damage to the electrical storage device packaging material during peeling, the thickness of the polyamide film is preferably at least about 3 μm, more preferably at least about 10 μm, and is preferably no more than about 50 μm, more preferably no more than about 35 μm. Preferred ranges include approximately 3 to 50 μm, approximately 3 to 35 μm, approximately 10 to 50 μm, and approximately 10 to 35 μm, with approximately 10 to 35 μm being particularly preferred.

Additives such as lubricants, flame retardants, antiblocking agents, antioxidants, light stabilizers, tackifiers, and antistatic agents may be present on at least one of the surface and interior of the polyamide film. A single type of additive may be used, or two or more types may be mixed together. Details of the additives are as explained in the section on the base material layer 1 of the exterior material 10 for an electricity storage device.

The present disclosure will be explained in detail below using examples and comparative examples. However, the present disclosure is not limited to the examples.

<Manufacturing of exterior materials for electricity storage devices>
Examples 1-3 and Comparative Examples 1-2
A stretched nylon (ONy) film (25 μm thick) was prepared as the substrate layer. As described below, the stretched nylon films used in Examples 1-3 and Comparative Examples 1-2 were adjusted to the crystallization index values listed in Table 1 by changing the stretch ratio and heat setting temperature. Erucic acid amide was applied to the stretched nylon film as a lubricant. An aluminum alloy foil (JIS H4160:1994 A8021H-O (40 μm thick)) was prepared as the barrier layer. An adhesive (two-component urethane adhesive) was then applied to one side of the aluminum alloy foil and allowed to dry. The adhesive on the barrier layer and the substrate layer were then laminated by dry lamination, followed by aging treatment to produce a substrate layer (25 μm thick)/adhesive layer (3 μm thick after curing)/barrier layer (40 μm thick) laminate. Both sides of the aluminum alloy foil were subjected to a chemical conversion treatment. The chemical conversion treatment of the aluminum alloy foil was performed by applying a treatment solution consisting of a phenolic resin, a chromium fluoride compound, and phosphoric acid to both sides of the aluminum alloy foil by roll coating so that the amount of chromium applied was 10 mg/ ^m2 (dry mass), and then baking the solution.

Next, maleic anhydride-modified polypropylene as an adhesive layer (23 μm thick) and random polypropylene as a heat-sealable resin layer (23 μm thick) were co-extruded onto the barrier layer of each of the laminates obtained above, thereby laminating the adhesive layer/heat-sealable resin layer on top of the barrier layer, and aging was performed to obtain a laminate (total thickness 114 μm) consisting of, from outside in, base layer (25 μm thick), adhesive layer (3 μm), barrier layer (40 μm), adhesive layer (23 μm), and heat-sealable resin layer (23 μm).

Example 4
An oriented nylon (ONy) film (thickness: 20 μm) was prepared as the substrate layer. As described below, the stretched nylon film used in Example 4 had its crystallization index adjusted to the values listed in Table 1 by changing the stretch ratio and heat setting temperature. The stretched nylon film had a coating layer (a polyester polyurethane containing a lubricant applied to a thickness of 300 nm or less) on the surface opposite the barrier layer, and another coating layer (a polyester polyurethane applied to a thickness of 300 nm or less) on the surface facing the barrier layer. An aluminum alloy foil (JIS H4160:1994 A8021H-O (thickness: 35 μm)) was prepared as the barrier layer. Next, an adhesive (a two-component urethane adhesive) was applied to one side of the aluminum alloy foil and allowed to dry. Next, the adhesive on the barrier layer and the substrate layer were laminated by dry lamination, and then aging treatment was performed to produce a laminate of substrate layer (thickness 20 μm)/adhesive layer (thickness 3 μm after curing)/barrier layer (thickness 35 μm). Both sides of the aluminum alloy foil were subjected to chemical conversion treatment. The chemical conversion treatment of the aluminum alloy foil was performed by applying a treatment solution consisting of a phenolic resin, a chromium fluoride compound, and phosphoric acid to both sides of the aluminum alloy foil by roll coating so that the coating amount of chromium was 10 mg/ ^m2 (dry mass), and baking.

Next, maleic anhydride-modified polypropylene as an adhesive layer (15 μm thick) and random polypropylene as a heat-sealable resin layer (15 μm thick) were co-extruded onto the barrier layer of each of the laminates obtained above, thereby laminating the adhesive layer/heat-sealable resin layer on top of the barrier layer, and aging was performed to obtain a laminate (total thickness 88 μm) consisting of, from outside in, a base layer (20 μm thick), adhesive layer (3 μm), barrier layer (35 μm), adhesive layer (15 μm), and heat-sealable resin layer (15 μm).

Example 5
An oriented nylon (ONy) film (thickness: 20 μm) was prepared as the substrate layer. The oriented nylon film used in Example 5 was the same as that used in Example 4. The oriented nylon film had a coating layer (a polyester polyurethane containing a lubricant applied to a thickness of 300 nm or less) on the surface opposite the barrier layer, and a coating layer (a polyester polyurethane applied to a thickness of 300 nm or less) on the surface facing the barrier layer. An aluminum alloy foil (JIS H4160:1994 A8021H-O (thickness: 30 μm)) was prepared as the barrier layer. Next, an adhesive (a two-component urethane adhesive) was applied to one side of the aluminum alloy foil and allowed to dry. Next, the adhesive on the barrier layer and the substrate layer were laminated by dry lamination, followed by aging treatment to produce a substrate layer (thickness: 20 μm)/adhesive layer (thickness: 3 μm after curing)/barrier layer (thickness: 30 μm). Both sides of the aluminum alloy foil were subjected to a chemical conversion treatment. The chemical conversion treatment of the aluminum alloy foil was performed by applying a treatment solution consisting of a phenolic resin, a chromium fluoride compound, and phosphoric acid to both sides of the aluminum alloy foil by roll coating so that the amount of chromium applied was 10 mg/ ^m2 (dry mass), and then baking the solution.

Next, maleic anhydride-modified polypropylene as an adhesive layer (14 μm thick) and random polypropylene as a heat-sealable resin layer (10 μm thick) were co-extruded onto the barrier layer of each of the laminates obtained above, thereby laminating the adhesive layer/heat-sealable resin layer on top of the barrier layer, and aging was performed to obtain a laminate (total thickness 77 μm) consisting of, from outside in, a base layer (20 μm thick), adhesive layer (3 μm), barrier layer (30 μm), adhesive layer (14 μm), and heat-sealable resin layer (10 μm).

Example 6
A laminate (total thickness 114 μm) having, from outside to inside, the following layers stacked in order: base material layer (thickness 25 μm), adhesive layer (3 μm), barrier layer (40 μm), adhesive layer (23 μm), and heat-fusible resin layer (23 μm) was obtained in the same manner as in Example 1, except that a stretched nylon (ONy) film having a coating layer (polyester polyurethane applied to a thickness of 300 nm or less) on the surface on the barrier layer side was used as the base material layer.

Example 7
An oriented nylon (ONy) film (thickness: 20 μm) was prepared as the substrate layer. The oriented nylon film used in Example 7 was the same as that used in Example 4. An aluminum alloy foil (JIS H4160:1994 A8021H-O (thickness: 35 μm)) was prepared as the barrier layer. Next, the barrier layer and the substrate layer were laminated by dry lamination using an adhesive (a two-component urethane adhesive containing carbon black), and then aging treatment was performed to produce a substrate layer (thickness: 20 μm)/adhesive layer (thickness: 3 μm after curing)/barrier layer (thickness: 35 μm). Both sides of the aluminum alloy foil were subjected to a chemical conversion treatment. The chemical conversion treatment of the aluminum alloy foil was performed by roll coating both sides of the aluminum alloy foil with a treatment solution consisting of a phenolic resin, a chromium fluoride compound, and phosphoric acid so that the coating amount of chromium was 10 mg/m ² (dry mass), followed by baking.

Next, maleic anhydride-modified polypropylene as an adhesive layer (thickness 15 μm) and random polypropylene as a heat-sealable resin layer (thickness 15 μm) were co-extruded onto the barrier layer of each laminate obtained above, thereby laminating the adhesive layer/heat-sealable resin layer on top of the barrier layer, thereby obtaining a laminate in which the substrate layer (thickness 20 μm)/adhesive layer (3 μm)/barrier layer (35 μm)/adhesive layer (15 μm)/heat-sealable resin layer (15 μm) were laminated in this order. Next, a two-component urethane resin containing silica particles and resin beads was applied to the surface of the stretched nylon film of the resulting laminate to a thickness of 3 μm to form a matte layer as a surface coating layer, and aging was performed to obtain a laminate (total thickness 91 μm) consisting of, from outside in, a surface coating layer (thickness 3 μm), a base layer (thickness 20 μm), an adhesive layer (3 μm), a barrier layer (35 μm), an adhesive layer (15 μm), and a heat-sealable resin layer (15 μm).

Example 8
An oriented nylon (ONy) film (thickness: 20 μm) was prepared as the substrate layer. The oriented nylon film used in Example 8 was the same as that used in Example 4. An aluminum alloy foil (JIS H4160:1994 A8021H-O (thickness: 40 μm)) was prepared as the barrier layer. Next, an adhesive (two-component urethane adhesive) was applied to one side of the aluminum alloy foil and allowed to dry. Next, the adhesive on the barrier layer and the substrate layer were laminated by dry lamination, and then aging treatment was performed to produce a laminate of substrate layer (thickness: 20 μm)/adhesive layer (thickness: 3 μm after curing)/barrier layer (thickness: 40 μm). Both sides of the aluminum alloy foil were subjected to a chemical conversion treatment. The chemical conversion treatment of the aluminum alloy foil was performed by applying a treatment solution consisting of a phenolic resin, a chromium fluoride compound, and phosphoric acid to both sides of the aluminum alloy foil by roll coating so that the amount of chromium applied was 10 mg/ ^m2 (dry mass), and then baking the solution.

Next, maleic anhydride-modified polypropylene as an adhesive layer (14 μm thick) and random polypropylene as a heat-sealable resin layer (10 μm thick) were co-extruded onto the barrier layer of each of the laminates obtained above, thereby laminating the adhesive layer/heat-sealable resin layer on top of the barrier layer, and aging was performed to obtain a laminate (total thickness 87 μm) consisting of, from outside in, a base layer (20 μm thick), adhesive layer (3 μm), barrier layer (40 μm), adhesive layer (14 μm), and heat-sealable resin layer (10 μm).

Example 9
An oriented nylon (ONy) film (thickness: 20 μm) was prepared as the substrate layer. The oriented nylon film used in Example 9 was the same as that used in Example 4. An aluminum alloy foil (JIS H4160:1994 A8021H-O (thickness: 40 μm)) was prepared as the barrier layer. Next, the barrier layer and the substrate layer were laminated by dry lamination using an adhesive (a two-component urethane adhesive containing carbon black), and then aging treatment was performed to produce a substrate layer (thickness: 20 μm)/adhesive layer (thickness: 3 μm after curing)/barrier layer (thickness: 40 μm). Both sides of the aluminum alloy foil were subjected to a chemical conversion treatment. The chemical conversion treatment of the aluminum alloy foil was performed by roll coating both sides of the aluminum alloy foil with a treatment solution consisting of a phenolic resin, a chromium fluoride compound, and phosphoric acid so that the coating amount of chromium was 10 mg/m ² (dry mass), followed by baking.

Next, maleic anhydride-modified polypropylene as an adhesive layer (thickness 14 μm) and random polypropylene as a heat-sealable resin layer (thickness 10 μm) were co-extruded onto the barrier layer of each laminate obtained above, thereby laminating the adhesive layer/heat-sealable resin layer on top of the barrier layer, thereby obtaining a laminate in which the substrate layer (thickness 20 μm)/adhesive layer (3 μm)/barrier layer (40 μm)/adhesive layer (14 μm)/heat-sealable resin layer (10 μm) were laminated in this order. Next, a two-component urethane resin containing silica particles and resin beads was applied to the surface of the stretched nylon film of the resulting laminate to a thickness of 3 μm to form a matte layer as a surface coating layer, and aging was performed to obtain a laminate (total thickness 90 μm) consisting of, from outside in, a surface coating layer (thickness 3 μm), a base layer (thickness 20 μm), an adhesive layer (3 μm), a barrier layer (40 μm), an adhesive layer (14 μm), and a heat-sealable resin layer (10 μm).

Example 10
An oriented nylon (ONy) film (thickness: 20 μm) was prepared as the substrate layer. The oriented nylon film used in Example 10 was the same as that used in Example 4. An aluminum alloy foil (JIS H4160:1994 A8021H-O (thickness: 40 μm)) was prepared as the barrier layer. Next, an adhesive (two-component urethane adhesive) was applied to one side of the aluminum alloy foil and allowed to dry. Next, the adhesive on the barrier layer and the substrate layer were laminated by dry lamination, and then aging treatment was performed to produce a laminate of substrate layer (thickness: 20 μm)/adhesive layer (thickness: 3 μm after curing)/barrier layer (thickness: 40 μm). Both sides of the aluminum alloy foil were subjected to a chemical conversion treatment. The chemical conversion treatment of the aluminum alloy foil was performed by applying a treatment solution consisting of a phenolic resin, a chromium fluoride compound, and phosphoric acid to both sides of the aluminum alloy foil by roll coating so that the amount of chromium applied was 10 mg/ ^m2 (dry mass), and then baking the solution.

Next, maleic anhydride-modified polypropylene as an adhesive layer (15 μm thick) and random polypropylene as a heat-sealable resin layer (15 μm thick) were co-extruded onto the barrier layer of each of the laminates obtained above, thereby laminating the adhesive layer/heat-sealable resin layer on top of the barrier layer, and aging was performed to obtain a laminate (total thickness 93 μm) consisting of, from outside in, a base layer (20 μm thick), adhesive layer (3 μm), barrier layer (40 μm), adhesive layer (15 μm), and heat-sealable resin layer (15 μm).

Example 11
An oriented nylon (ONy) film (thickness: 20 μm) was prepared as the substrate layer. The oriented nylon film used in Example 11 was the same as that used in Example 4. An aluminum alloy foil (JIS H4160:1994 A8021H-O (thickness: 40 μm)) was prepared as the barrier layer. Next, the barrier layer and the substrate layer were laminated by dry lamination using an adhesive (a two-component urethane adhesive containing carbon black), and then aging treatment was performed to produce a substrate layer (thickness: 20 μm)/adhesive layer (thickness: 3 μm after curing)/barrier layer (thickness: 40 μm). Both sides of the aluminum alloy foil were subjected to a chemical conversion treatment. The chemical conversion treatment of the aluminum alloy foil was performed by roll coating both sides of the aluminum alloy foil with a treatment solution consisting of a phenolic resin, a chromium fluoride compound, and phosphoric acid so that the coating amount of chromium was 10 mg/m ² (dry mass), followed by baking.

Next, maleic anhydride-modified polypropylene as an adhesive layer (thickness 14 μm) and random polypropylene as a heat-sealable resin layer (thickness 10 μm) were co-extruded onto the barrier layer of each laminate obtained above, thereby laminating the adhesive layer/heat-sealable resin layer on top of the barrier layer, thereby obtaining a laminate in which the substrate layer (thickness 20 μm)/adhesive layer (3 μm)/barrier layer (40 μm)/adhesive layer (15 μm)/heat-sealable resin layer (15 μm) were laminated in this order. Next, a two-component urethane resin containing silica particles and resin beads was applied to the surface of the stretched nylon film of the resulting laminate to a thickness of 3 μm to form a matte layer as a surface coating layer, and aging was performed to obtain a laminate (total thickness 96 μm) consisting of, from outside in, a surface coating layer (thickness 3 μm), a base layer (thickness 20 μm), an adhesive layer (3 μm), a barrier layer (40 μm), an adhesive layer (15 μm), and a heat-sealable resin layer (15 μm).

<Measurement of Crystallization Index of Base Material Layer of Exterior Material for Electricity Storage Device>
The exterior material for a power storage device was cut into a 100 mm x 100 mm square to prepare a sample. The surface of the stretched nylon film located on the outside of the obtained sample was subjected to infrared absorption spectroscopy at a temperature of 25°C and a relative humidity of 50% using a Nicolet iS10 FT-IR (manufactured by Thermo Fisher Scientific) in ATR mode. From the obtained absorption spectrum, the peak intensity P near 1200 cm ⁻¹ resulting from the absorption of nylon α crystals and the peak intensity Q near 1370 cm ⁻¹ resulting from absorption unrelated to crystals were measured, and the intensity ratio X = P/Q of the peak intensity P to the peak intensity Q was calculated as the crystallization index. For Examples 7, 9, and 11, the measurement was performed before the surface coating layer was applied. The results are shown in Table 1.
(Measurement conditions)
Method: Macro ATR method Wavenumber resolution: 8cm ^-1
Number of integrations: 32 times Detector: DTGS detector ATR prism: Ge
Incident angle: 45°
Baseline: Obtained as a linear approximation between wave numbers 1100 cm ⁻¹ and 1400 cm ⁻¹ .
Absorption peak intensity Y ₁₂₀₀ : the value obtained by subtracting the baseline value from the maximum peak intensity in the wavenumber range of 1195 cm ⁻¹ to 1205 cm ⁻¹ Absorption peak intensity Y ₁₃₇₀ : the value obtained by subtracting the baseline value from the maximum peak intensity in the wavenumber range of 1365 cm ⁻¹ to 1375 cm ⁻¹

<Measurement of Crystallization Index of Stretched Nylon Film>
The stretched nylon film used as the base layer of the exterior material for a power storage device was cut into a 100 mm x 100 mm square to prepare a sample. The surface of the obtained sample was subjected to infrared absorption spectroscopy at a temperature of 25°C and a relative humidity of 50% using a Nicolet iS10 FT-IR (manufactured by Thermo Fisher Scientific) in ATR mode. From the obtained absorption spectrum, the peak intensity P near 1200 cm ⁻¹ resulting from the absorption of α-crystals of nylon and the peak intensity Q near 1370 cm ⁻¹ resulting from absorption unrelated to crystals were measured, and the intensity ratio X = P/Q of the peak intensity P to the peak intensity Q was calculated as the crystallization index. The results are shown in Table 1.
(Measurement conditions)
Method: Macro ATR method Wavenumber resolution: 8cm ^-1
Number of integrations: 32 times Detector: DTGS detector ATR prism: Ge
Incident angle: 45°
Baseline: Obtained as a linear approximation between wave numbers 1100 cm ⁻¹ and 1400 cm ⁻¹ .
Absorption peak intensity Y ₁₂₀₀ : the value obtained by subtracting the baseline value from the maximum peak intensity in the wavenumber range of 1195 cm ⁻¹ to 1205 cm ⁻¹ Absorption peak intensity Y ₁₃₇₀ : the value obtained by subtracting the baseline value from the maximum peak intensity in the wavenumber range of 1365 cm ⁻¹ to 1375 cm ⁻¹

<Electricity storage device peeling test>
A peel test for an electricity storage device was performed according to the following procedure. This procedure will be described with reference to FIGS. 5 to 8 . First, the procedure for preparing a sample used in the peel test for an electricity storage device will be described with reference to FIG. 5 . As shown in FIG. 5 a, an electrical storage device packaging material was cut into a rectangular shape measuring 200 mm in length (MD) and 90 mm in width (TD). Next, using a molding die (female die) with a diameter of 55 mm in length (MD) x 32 mm in width (TD) and a corresponding molding die (male die), the electrical storage device packaging material was cold-molded to a depth of 5.0 mm from the heat-sealable resin layer side at a position 15 mm away from the short side, forming a recess M (the area surrounded by the dashed line in FIG. 5 a). Next, an acrylic plate measuring 55 mm in length, 32 mm in width, and 5 mm in thickness was inserted into the recess M ( FIGS. 5 b and 5 c). Next, the molded electrical storage device packaging material was folded in half in the TD direction at the crease P (along the short side of the recess M) with the recess M facing inward (FIG. 5d). Next, along the periphery of the recess M, the overlapping portions of the thermally adhesive resin layers were heat-sealed (190°C, 3 seconds, surface pressure 1 MPa) in three locations along the MD and TD to seal the recess M (FIG. 5e). In FIG. 5e, the colored area S represents the heat-sealed portion. Next, as shown in FIG. 5f, the sample was trimmed to a size of 60 mm in length (MD) and 37 mm in width (TD) along the recess M to prepare sample 12 for use in peel testing of electrical storage devices. FIG. 6 shows a side view (FIG. 6a) and a plan view (FIG. 6b) of sample 12.

Next, as shown in the schematic diagram of Figure 7, three strips of double-sided tape (7.5 mm wide, 55 mm long) were attached to both ends and the center of the flat surface of sample 12 (the surface opposite the surface on which recesses M were formed) in the machine direction (MD). The peel strength of the double-sided tape to the object was measured using the method described below.

Next, Sample 12 with the double-sided tape attached was attached to a stainless steel plate and cured in an environment of 60°C for 24 hours. The stainless steel plate served as a housing to which the electricity storage device was fixed with the double-sided tape. Next, as shown in the schematic diagram of FIG. 8 , Sample 12 was carefully peeled off from the stainless steel plate using a metal spatula, and the peeled Sample 12 was visually inspected for the presence or absence of holes. Three samples were evaluated in the electricity storage device peel test according to the following criteria. As shown in FIG. 8 , the electricity storage device was peeled off by applying force from the lateral direction (TD) of Sample 12. The results are shown in Table 1. A: No holes were present in any of the three samples.
B: One or two samples had holes.
C: All three samples had holes.

The electrical storage device packaging materials of Examples 1 to 11 are composed of a laminate including, in order from the outside, at least a base layer, a barrier layer, and a heat-sealable resin layer. The base layer includes a polyamide film, and the polyamide film has a crystallization index of 1.50 or more as measured from the outside of the base layer by the ATR method of Fourier transform infrared spectroscopy. Furthermore, the polyamide film used in the base layer of the electrical storage device packaging materials of Examples 1 to 11 has a crystallization index of 1.50 or more as measured by the ATR method of Fourier transform infrared spectroscopy. It can be seen that the electrical storage device packaging materials of Examples 1 to 11 effectively prevent damage to the electrical storage device packaging materials when an electrical storage device fixed with double-sided tape or the like is peeled off from a housing.

The difference between the crystallization index measured for the base layer of the electrical storage device casing material and the crystallization index measured for the stretched nylon film is thought to be due to the aging of the electrical storage device casing material. The stretched nylon film used in Comparative Examples 1 and 2 had a crystallization index value significantly lower than that of Examples 1 to 11, but the value measured after it was used as the base layer of the electrical storage device casing material was significantly higher than the value measured in the stretched nylon film state. However, in Comparative Examples 1 and 2, the crystallization index of the polyamide film measured from the outside of the base layer did not increase to 1.50 or higher after aging of the electrical storage device casing material, and the peel test evaluation of the electrical storage device was inferior to that of Examples 1 to 11.

(Measurement of peel strength of double-sided tape)
The electrical storage device exterior materials (15 mm long x 70 mm wide) of Examples 1 to 11, the double-sided tape (7.5 mm long x 60 mm wide) used in the "Electricity Storage Device Peel Test," aluminum foil (35 μm thick x 15 mm long x 150 mm wide), a fixing double-sided adhesive tape (5 mm long x 60 mm wide), and an acrylic plate (3 mm thick x 50 mm long x 70 mm wide) were prepared. First, the stretched nylon film side of the electrical storage device exterior material (the surface of the coating layer on the stretched nylon film for Examples 4 and 5, and the surface of the surface coating layer on the stretched nylon film for Examples 7, 9, and 11) was bonded to one side of the double-sided tape, and aluminum foil was then bonded to the other side of the double-sided tape. A 2 kg roller was then rolled back and forth over the aluminum foil to obtain a laminate P. Furthermore, a laminate Q was obtained by bonding an acrylic plate to one side of the fixing double-sided adhesive tape. Furthermore, the surface of the heat-fusible resin layer of the electrical storage device exterior material of the laminate P was attached to the other side of the fixing double-sided adhesive tape of the laminate Q, and pressed down by hand to obtain a laminate R in which an acrylic plate, fixing double-sided adhesive tape, electrical storage device exterior material, double-sided tape, and aluminum foil were laminated in that order, and this was designated as test sample M. Test sample M was stored in an environment at a temperature of 60°C for 24 hours. Next, the stretched nylon film surface of the electrical storage device exterior material was peeled off from the end of the double-sided tape by about 1 mm, providing a trigger point for measuring peel strength. Next, the acrylic plate of test sample M was fixed, and using a tensile tester (manufactured by Shimadzu Corporation, AG-Xplus (trade name)), the aluminum foil was pulled at a pulling angle of 180°, a peeling rate of 300 mm/min, and a peeling distance of 50 mm or more, and the aluminum foil was peeled at the interface between the stretched nylon film surface of the electrical storage device exterior material and the double-sided tape (from the trigger point), and the peel strengths at peeling distances of 10 mm, 20 mm, 30 mm, and 40 mm, as well as the maximum peel strength between 10 and 40 mm, were averaged to calculate the peel strength (peel strength of the double-sided tape to the stretched nylon film (N/7.5 mm)). The results are shown in Table 2.

Next, a stainless steel plate (3 mm thick x 50 mm long x 70 mm wide), double-sided tape (7.5 mm long x 60 mm wide), and the aforementioned aluminum foil (35 μm thick x 15 mm long x 150 mm wide) were prepared for use in the <Peel Test for Energy Storage Devices>. One side of the double-sided tape was bonded to the surface of the stainless steel plate, and aluminum foil was then bonded to the other side of the double-sided tape. A 2 kg roller was rolled back and forth over the aluminum foil to obtain a laminate, designated Test Sample N. Test Sample N was stored in an environment at 60°C for 24 hours. Next, the edge of the double-sided tape was peeled approximately 1 mm from the surface of the stainless steel plate to create a trigger point for measuring peel strength. Next, the stainless steel plate of test sample N was fixed in place, and using a tensile tester (Shimadzu Corporation, AG-Xplus (trade name)), the aluminum foil was pulled at a pull angle of 180°, a peel rate of 300 mm/min, and a peel distance of at least 50 mm. The aluminum foil was peeled at the interface between the stainless steel plate surface and the double-sided tape (from the aforementioned peel trigger point). The peel strength was calculated from the average of five peel strengths: peel strengths at peel distances of 10 mm, 20 mm, 30 mm, and 40 mm, and the maximum peel strength between 10 and 40 mm, and this was taken as the peel strength (peel strength of the double-sided tape to the stainless steel plate (N/7.5 mm)). The results are shown in Table 2.

As is clear from the results shown in Table 2, the peel strength of the double-sided tape used in the "Electricity Storage Device Peel Test" was comparable to that of the stretched nylon film and stainless steel plate.

As described above, the present disclosure provides the following aspects of the invention.
Item 1. The device is composed of a laminate including, in order from the outside, at least a base layer, a barrier layer, and a heat-sealable resin layer,
the substrate layer includes a polyamide film,
An outer casing material for an electricity storage device, wherein the polyamide film has a crystallization index of 1.50 or more as measured from the outside of the base material layer by an ATR method of Fourier transform infrared spectroscopy.
Item 2. The packaging material for an electricity storage device according to Item 1, further comprising an adhesive layer between the base layer and the barrier layer.
Item 3. The packaging material for an electricity storage device according to Item 1 or 2, further comprising an adhesive layer between the barrier layer and the heat-sealable resin layer.
Item 4. The method includes a step of obtaining a laminate in which at least a base layer, a barrier layer, and a thermally adhesive resin layer are laminated in this order from the outside,
the substrate layer includes a polyamide film,
A method for producing an exterior material for an electricity storage device, wherein the polyamide film has a crystallization index of 1.50 or more as measured from the outside of the base material layer by an ATR method of Fourier transform infrared spectroscopy.
Item 5. An electricity storage device, in which an electricity storage device element including at least a positive electrode, a negative electrode, and an electrolyte is housed in a package formed from the exterior material for an electricity storage device according to any one of Items 1 to 3.
Item 6. A polyamide film for use in a base material layer of an electrical storage device packaging material composed of a laminate including at least a base material layer, a barrier layer, and a heat-sealable resin layer,
The polyamide film has a crystallization index of 1.50 or more as measured by the ATR method of Fourier transform infrared spectroscopy.

REFERENCE SIGNS LIST 1 Base material layer 2 Adhesive layer 3 Barrier layer 4 Heat-sealable resin layer 5 Adhesive layer 6 Surface coating layer 10 Electricity storage device packaging material

Claims (9)

The laminate is composed of at least a base layer, a barrier layer, and a heat-sealable resin layer, in this order from the outside,
the substrate layer includes a polyamide film having a thickness of 10 μm or more and 35 μm or less,
the substrate layer is a single layer,
An outer casing material for an electricity storage device, wherein the polyamide film has a crystallization index of 1.50 or more as measured from the outside of the base material layer by an ATR method of Fourier transform infrared spectroscopy. The exterior packaging material for an electricity storage device according to claim 1, wherein the thickness of the barrier layer is 25 μm or more and 50 μm or less. an adhesive layer is further provided between the barrier layer and the thermal adhesive resin layer,
The packaging material for an electricity storage device according to claim 1 or 2, wherein the adhesive layer has a thickness of 0.1 μm or more and 20 μm or less. The packaging material for an electricity storage device according to any one of claims 1 to 3, wherein the thickness of the heat-sealable resin layer is 10 μm or more and 23 μm or less. The exterior packaging material for an electricity storage device according to any one of claims 1 to 4, further comprising an adhesive layer between the base layer and the barrier layer. The packaging material for an electricity storage device according to any one of claims 1 to 5, further comprising an adhesive layer between the barrier layer and the heat-sealable resin layer. The method includes a step of obtaining a laminate in which at least a base layer, a barrier layer, and a thermally adhesive resin layer are laminated in this order from the outside,
the substrate layer includes a polyamide film having a thickness of 10 μm or more and 35 μm or less,
the substrate layer is a single layer,
A method for producing an exterior material for an electricity storage device, wherein the polyamide film has a crystallization index of 1.50 or more as measured from the outside of the base material layer by an ATR method of Fourier transform infrared spectroscopy. An electricity storage device in which an electricity storage device element having at least a positive electrode, a negative electrode, and an electrolyte is housed in a package formed from the exterior packaging material for an electricity storage device according to any one of claims 1 to 6. A polyamide film having a thickness of 10 μm or more and 35 μm or less, for use as a substrate layer of an exterior material for an electricity storage device, the exterior material being composed of a laminate including at least a substrate layer, a barrier layer, and a heat-sealable resin layer,
the substrate layer is a single layer,
The polyamide film has a crystallization index of 1.50 or more as measured by the ATR method of Fourier transform infrared spectroscopy.