JP2020119756A - Exterior material for power storage device, manufacturing method thereof, and power storage device - Google Patents

Abstract

To provide an exterior material for a power storage device, which allows the high adhesion of a barrier layer having a corrosion resistant coating to be kept even if an electrolyte solution deposits thereto.SOLUTION: An exterior material for a power storage device comprises at least a laminate having a base material layer, a barrier layer and a heat-fusable resin layer in this order. The base material layer is composed of a monolayer polyester film. The barrier layer has a corrosion resistant coating on at least one surface thereof. According to analysis by the time-of-flight secondary ion mass spectrometry on the corrosion resistant coating, the ratio P/Pof a peak intensity Poriginating from POto a peak intensity Poriginating from CePOfalls within a range of 80 or more and 120 or less.SELECTED DRAWING: None

Description

The present disclosure relates to an exterior material for an electricity storage device, a method for manufacturing an exterior material for an electricity storage device, and an electricity storage device.

Conventionally, various types of power storage devices have been developed. In these power storage devices, the power storage device element composed of an electrode, an electrolyte and the like needs to be sealed with an exterior material or the like. As the exterior material for the electricity storage device, a metal exterior material is often used.

2. Description of the Related Art In recent years, as electric vehicles, hybrid electric vehicles, personal computers, cameras, mobile phones, and the like have improved in performance, power storage devices having various shapes have been required. In addition, power storage devices are required to be thinner and lighter. However, it is difficult to follow the diversification of the shape of the electricity storage device with the metal-made exterior material that has been widely used conventionally. Further, since it is made of metal, there is a limit to reducing the weight of the exterior material.

Therefore, a film-like laminate in which a base material layer/barrier layer/heat-fusible resin layer is sequentially laminated as an exterior material for an electricity storage device that can be easily processed into various shapes and can be made thin and lightweight. Has been proposed (for example, see Patent Document 1).

In such a film-like exterior material for an electricity storage device, generally, a recess is formed by molding, and an electricity storage device element such as an electrode or an electrolytic solution is arranged in the space formed by the recess, and the heat sealing property is obtained. By heat-sealing the resin layers to each other, an electricity storage device in which an electricity storage device element is housed inside the exterior material for an electricity storage device is obtained.

JP 2008-287971 A

When water enters the inside of the electricity storage device, the water may react with an electrolyte or the like to generate an acidic substance. For example, an electrolytic solution used in a lithium ion electricity storage device or the like contains a fluorine compound (LiPF ₆ , LiBF _4, etc.) as an electrolyte, and when the fluorine compound reacts with water, hydrogen fluoride is generated. It is known.

The barrier layer of the exterior material for an electricity storage device, which is formed by the film-shaped laminate, is usually composed of a metal foil or the like, and there is a problem that corrosion is likely to occur when an acid contacts the barrier layer. As a technique for increasing the acid resistance of such an exterior material for an electricity storage device, a technique using a barrier layer having a corrosion resistant film formed on its surface by chemical conversion treatment is known.

Conventionally, various methods such as a chromate treatment using a chromium compound such as chromium oxide and a phosphoric acid treatment using a phosphoric acid compound are known as chemical conversion treatments for forming a corrosion resistant film.

However, the inventors of the present disclosure have conducted extensive studies and found that a conventional barrier layer provided with a corrosion-resistant coating has good adhesion (ie, corrosion resistance) to a layer adjacent to the side provided with the corrosion-resistant coating. It became clear that the adhesiveness at the interface between the film and the layer in contact therewith becomes insufficient. More specifically, when the electrolytic solution adheres to the exterior material for an electricity storage device, high adhesion between the corrosion resistant coating and the layer in contact with the coating may not be maintained in some cases.

Under such circumstances, the present disclosure mainly aims to provide an exterior material for an electricity storage device in which high adhesion of a barrier layer provided with a corrosion resistant film is maintained even when an electrolytic solution is attached. .. Another object of the present disclosure is to provide a method for manufacturing the exterior material for an electricity storage device, and an electricity storage device using the exterior material for an electricity storage device.

The inventors of the present disclosure have made earnest studies to solve the above problems. As a result, at least, a base material layer, a barrier layer, and a heat-fusible resin layer is composed of a laminate provided in this order, the base material layer is composed of a single-layer polyester film, At least one surface of the barrier layer is provided with a corrosion-resistant film, and when the corrosion-resistant film is analyzed by time-of-flight secondary ion mass spectrometry, it is derived from CePO ₄ ⁻ . PO ₃ to the peak intensity P _CePO4 that ^- the ratio P _PO3 / P _CePO4 peak intensity P _PO3 derived is the storage device for sheathing material in the range of 80 to 120 or less, higher even when the electrolyte has attached It was found that the adhesiveness is maintained. The present disclosure is an invention completed by further studies based on these findings.

That is, the present disclosure provides the inventions of the following modes.
At least a base material layer, a barrier layer, and a heat-fusible resin layer is composed of a laminate provided in this order,
The base layer is composed of a single-layer polyester film,
At least one surface of the barrier layer is provided with a corrosion resistant film,
When the above corrosion-resistant film is analyzed using time-of-flight secondary ion mass spectrometry, the ratio of the peak intensity P _PO3 derived from PO ₃ ⁻ to the peak intensity P _CePO4 derived from CePO ₄ ⁻ P _PO3 / An exterior material for an electricity storage device, in which P _CePO4 is in the range of 80 or more and 120 or less.

According to the present disclosure, it is possible to provide a packaging material for an electricity storage device in which high adhesion of a barrier layer provided with a corrosion resistant film is maintained even when an electrolytic solution is attached. Further, according to the present disclosure, it is possible to provide a method for manufacturing the exterior material for an electricity storage device, and an electricity storage device using the exterior material for an electricity storage device.

FIG. 3 is a schematic diagram showing an example of a cross-sectional structure of a power storage device exterior material of the present disclosure. FIG. 3 is a schematic diagram showing an example of a cross-sectional structure of a power storage device exterior material of the present disclosure. FIG. 3 is a schematic diagram showing an example of a cross-sectional structure of a power storage device exterior material of the present disclosure. FIG. 3 is a schematic diagram showing an example of a cross-sectional structure of a power storage device exterior material of the present disclosure.

The exterior material for an electricity storage device of the present disclosure is composed of a laminate including at least a base material layer, a barrier layer, and a heat-fusible resin layer in this order, and the base material layer is a single-layer polyester. In the case where the barrier layer is composed of a film and has a corrosion resistant coating on the surface of at least one side of the barrier layer, the corrosion resistant coating is analyzed using time-of-flight secondary ion mass spectrometry. In addition, the ratio P _PO3 /P _CePO4 of the peak intensity P _PO3 derived from PO ₃ ⁻ to the peak intensity P _CePO4 derived from CePO ₄ ⁻ is in the range of 80 or more and 120 or less.

Hereinafter, with reference to FIGS. 1 to 4, the exterior material for an electricity storage device, the method for manufacturing the exterior material for an electricity storage device, and the electricity storage device using the exterior material for an electricity storage device according to the present disclosure will be described in detail.

In addition, in this specification, the numerical range shown by "-" means "more than" and "less than". For example, the notation 2 to 15 mm means 2 mm or more and 15 mm or less.

1. Laminated Structure of Exterior Material for Energy Storage Device The exterior material for an energy storage device according to the present disclosure includes at least the base material layer 1, the barrier layer 3, and the heat-fusible resin layer 4 as shown in FIGS. 1 to 4. It is composed of a laminated body having in order. In the exterior material for an electricity storage device of the present disclosure, the base material layer 1 is the outermost layer side, and the heat-fusible resin layer 4 is the innermost layer. That is, at the time of assembling the electricity storage device, the heat-fusible resin layers 4 located on the periphery of the electricity storage device element are heat-sealed to seal the electricity storage device element, whereby the electricity storage device element is sealed.

At least one surface of the barrier layer 3 is provided with a corrosion resistant film. The corrosion resistant film contains cerium. 1 to 4 are schematic diagrams showing a case where the exterior material for an electricity storage device of the present disclosure is provided with a corrosion resistant coating 3a on the surface of the barrier layer 3 on the side of the heat-fusible resin layer 4. In addition, FIGS. 2 to 4 are schematic diagrams in which the exterior material for an electricity storage device of the present disclosure includes the corrosion-resistant coatings 3 a and 3 b on both surfaces of the barrier layer 3, respectively. As will be described later, in the exterior material for an electricity storage device of the present disclosure, the corrosion resistant coating 3a may be provided only on the surface of the barrier layer 3 on the side of the heat-fusible resin layer 4, or the barrier layer 3 may be provided. The corrosion resistant coating 3b may be provided only on the surface of the base material layer 1 side, or the corrosion resistant coatings 3a and 3b may be provided on both surfaces of the barrier layer 3, respectively.

As shown in FIG. 3 and FIG. 4, the exterior material for an electricity storage device according to the present disclosure may include an adhesive layer between the base material layer 1 and the barrier layer 3 for the purpose of enhancing the adhesiveness thereof, if necessary. 2 may be provided. Further, as shown in FIGS. 3 and 4, an adhesive layer 5 may be provided between the barrier layer 3 and the heat-fusible resin layer 4 for the purpose of enhancing the adhesiveness thereof, if necessary. Good. In addition, as shown in FIG. 4, the exterior material for an electricity storage device of the present disclosure has, as necessary, the base layer 1 for the purpose of improving designability, electrolytic solution resistance, scratch resistance, and moldability. If necessary, a surface coating layer 6 may be provided on the side opposite to the barrier layer 3.

The thickness of the laminate constituting the exterior material 10 for an electricity storage device is not particularly limited, but the upper limit is preferably about 180 μm or less, about 155 μm or less, about 120 μm or less from the viewpoint of cost reduction, energy density improvement and the like. The lower limit is preferably about 35 μm or more, about 45 μm or more, about 60 μm or more, about 100 μm or more, from the viewpoint of maintaining the function of the power storage device exterior material of protecting the power storage device element. About a preferable range, for example, about 35 to 180 μm, about 35 to 155 μm, about 35 to 120 μm, about 45 to 180 μm, about 45 to 155 μm, about 45 to 120 μm, about 60 to 180 μm, about 60 to 155 μm, 100 to 155 μm And about 60 to 120 μm, and of these, about 100 to 155 μm is particularly preferable.

In the exterior material 10 for an electricity storage device of the present disclosure, considering the balance of the lamination configuration of the exterior material 10 for an electricity storage device, the following laminated configurations 1 and 2 are mentioned as particularly preferable specific laminated configurations.
Lamination structure 1: Base material layer 1 (thickness 22 to 28 μm)/adhesive layer 2 (thickness 2 to 5 μm) composed of a single-layer polyethylene terephthalate film/corrosion resistant coatings 3a and 3b described later on both sides Barrier layer 3 (thickness 35 to 45 μm) made of the formed aluminum alloy foil/adhesive layer 5 (thickness 12 to 18 μm) made of acid-modified polypropylene/heat-fusible resin layer made of polypropylene 4 (thickness 25 to 35 μm) is laminated in this order.
Lamination structure 2: Base material layer 1 (thickness 22 to 28 μm)/adhesive layer 2 (thickness 2 to 5 μm) composed of a single-layer polyethylene terephthalate film/corrosion resistant coatings 3a and 3b described later on both sides Barrier layer 3 (thickness 35 to 45 μm) made of the formed aluminum alloy foil/adhesive layer 5 (thickness 22 to 28 μm) made of acid-modified polypropylene/heat-fusible resin layer made of polypropylene 4 (thickness 50 to 60 μm) is laminated in this order.

In the exterior material for an electricity storage device, with respect to the barrier layer 3 described later, it is usually possible to distinguish between the vertical direction (MD) and the horizontal direction (TD) in the manufacturing process. For example, when the barrier layer 3 is made of an aluminum alloy foil, linear streaks called so-called rolling marks are formed on the surface of the aluminum alloy foil in the rolling direction (RD: Rolling Direction) of the aluminum alloy foil. ing. Since the rolling mark extends along the rolling direction, the rolling direction of the aluminum alloy foil can be grasped by observing the surface of the aluminum alloy foil. In addition, in the manufacturing process of the laminated body, since the MD of the laminated body and the RD of the aluminum alloy foil usually match, the surface of the aluminum alloy foil of the laminated body is observed and the rolling direction (RD) of the aluminum alloy foil is observed. By specifying, the MD of the laminated body can be specified. Further, since the TD of the laminated body is in the direction perpendicular to the MD of the laminated body, the TD of the laminated body can be specified.

2. Each layer forming the exterior material for a power storage device [base material layer 1]
In the present disclosure, the base material layer 1 is a layer provided for the purpose of exerting a function as a base material of the exterior material for an electricity storage device. The base material layer 1 is located on the outer layer side of the exterior material 10 for an electricity storage device.

In the present disclosure, the base material layer 1 is composed of a single-layer polyester film. More specifically, in the electricity storage device exterior material 10 of the present disclosure, the number of the polyester film existing outside the barrier layer 3 is one layer, and the polyester film constitutes the base material layer 1.

The polyester film may be an unstretched film or a stretched film. Examples of the stretched film include a uniaxially stretched film and a biaxially stretched film, and a biaxially stretched film is preferable. Examples of the stretching method for forming the biaxially stretched film include a sequential biaxial stretching method, an inflation method and a simultaneous biaxial stretching method.

Specific examples of the polyester constituting the polyester film include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolyester. Examples of the copolyester include a copolyester having ethylene terephthalate as a main repeating unit. Specifically, a copolymer polyester (hereinafter, abbreviated to polyethylene (terephthalate/isophthalate)) in which ethylene terephthalate is a main repeating unit and is polymerized with ethylene isophthalate, polyethylene (terephthalate/adipate), polyethylene (terephthalate/ Sodium sulfoisophthalate), polyethylene (terephthalate/sodium isophthalate), polyethylene (terephthalate/phenyl-dicarboxylate), polyethylene (terephthalate/decanedicarboxylate), and the like. These polyesters may be used alone or in combination of two or more.

The polyester film is preferably a polyethylene terephthalate film. The main resin (for example, 80% by mass or more, further 90% by mass or more) constituting the polyethylene terephthalate film is polyethylene terephthalate, and in addition, for example, polybutylene terephthalate or the like may be contained.

At least one of the surface and the inside of the polyester film constituting the base material layer 1 has additives such as a lubricant, a flame retardant, an antiblocking agent, an antioxidant, a light stabilizer, a tackifier, and an antistatic agent. May be. As the additive, only one kind may be used, or two or more kinds may be mixed and used.

In the present disclosure, a lubricant is preferably present on the surface of the base material layer 1 from the viewpoint of enhancing the moldability of the exterior material for an electricity storage device. The lubricant is not particularly limited, but preferably an amide lubricant is used. Specific examples of the amide-based lubricant include saturated fatty acid amide, unsaturated fatty acid amide, substituted amide, methylol amide, saturated fatty acid bisamide, unsaturated fatty acid bisamide, fatty acid ester amide, aromatic bisamide, and the like. Specific examples of the saturated fatty acid amide 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 the substituted amide include N-oleyl palmitate 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 methylolamide include methylolstearic acid amide. Specific examples of the saturated fatty acid bisamide include methylenebisstearic acid amide, ethylenebiscapric acid amide, ethylenebislauric acid amide, ethylenebisstearic acid amide, ethylenebishydroxystearic acid amide, ethylenebisbehenic acid amide, and hexamethylenebisstearic acid amide. Examples thereof include acid amide, hexamethylene bisbehenic acid amide, hexamethylene hydroxystearic acid amide, N,N′-distearyl adipic acid amide, and N,N′-distearyl sebacic acid amide. Specific examples of the unsaturated fatty acid bisamide include ethylene bisoleic acid amide, ethylene bis erucic acid amide, hexamethylene bis oleic acid amide, N,N′-dioleyl adipate amide, N,N′-dioleyl sebacic acid amide. And so on. Specific examples of the fatty acid ester amide include stearoamide ethyl stearate. Further, specific examples of the aromatic bisamide include m-xylylenebisstearic acid amide, m-xylylenebishydroxystearic acid amide, N,N'-distearylisophthalic acid amide and the like. The lubricant may be used alone or in combination of two or more.

If a lubricant on the surface of the base material layer 1 is present, as it is its abundance is not particularly limited, preferably about 3 mg / m ² or more, more preferably 4~15mg / m ² approximately, more preferably 5~14mg /M ² can be mentioned.

The lubricant present on the surface of the base material layer 1 may be one in which the lubricant contained in the resin constituting the base material layer 1 is exuded, or the lubricant is applied to the surface of the base material layer 1. May be.

The thickness of the base material layer 1 is not particularly limited as long as it exhibits a function as a base material, but preferably about 3 to 50 μm, about 10 to 35 μm, and about 22 to 28 μm. Among these, the thickness of the base material layer 1 is particularly preferably in the range of 22 to 28 μm.

The tensile rupture strength of at least one direction (perpendicular to the thickness direction) of the polyester film constituting the base material layer 1 is preferably about 50 to 90 N/15 mm, more preferably about 60 to 80 N/15 mm. More specifically, the tensile breaking strength of the polyester film in the MD direction is preferably about 50 to 90 N/15 mm, more preferably about 60 to 80 N/15 mm. The tensile rupture strength of the polyester film in the TD direction is preferably about 60 to 80 N/15 mm, more preferably about 60 to 75 N/15 mm. The tensile breaking strength of the polyester film constituting the base material layer 1 is a value measured by the following method.

<Tensile breaking strength of polyester film>
Tensile breaking strength in the machine direction (MD) and the transverse direction (TD) of the polyester film is measured using a tensile tester (for example, AG-Xplus (trade name) manufactured by Shimadzu Corporation). The measurement conditions are a rectangular shape with a sample width of 15 mm, a distance between marked lines of 50 mm, a pulling speed of 50 mm/min, and a test environment of 23°C.

From the viewpoint of enhancing the moldability of the exterior material for an electricity storage device of the present disclosure, the tensile breaking strength of the polyester film is preferably small in the machine direction (MD) and the transverse direction (TD), and the difference is 0 to 10 N. It is preferably about /15 mm.

[Adhesive layer 2]
In the exterior material for an electricity storage device of the present disclosure, the adhesive layer 2 is a layer provided between the base material layer 1 and the barrier layer 3, if necessary, for the purpose of enhancing the adhesiveness between the base material layer 1 and the barrier layer 3.

The adhesive layer 2 is formed of an adhesive that can bond the base material layer 1 and the barrier layer 3 together. The adhesive used for forming the adhesive layer 2 is not limited, and may be any of a chemical reaction type, a solvent volatilization type, a heat melting type, a heat pressure type and the like. Further, it may be a two-component curing type adhesive (two-component adhesive), a one-component curing type adhesive (one-component adhesive), or a resin that does not undergo a curing reaction. The adhesive layer 2 may be a single layer or a multilayer.

Specific examples of the adhesive component contained in the adhesive include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, polyesters such as copolyester; polyether; polyurethane; epoxy resin; Phenol resin; nylon 6, nylon 66, nylon 12, polyamide such as copolyamide; polyolefin resin such as polyolefin, cyclic polyolefin, acid-modified polyolefin, acid-modified cyclic polyolefin; polyvinyl acetate; cellulose; (meth)acrylic resin; Polyimide; polycarbonate; amino resins such as urea resin and melamine resin; rubber such as chloroprene rubber, nitrile rubber and styrene-butadiene rubber; silicone resin and the like. These adhesive components may be used alone or in combination of two or more. Among these adhesive components, a polyurethane adhesive is preferable. In addition, the resin serving as the adhesive component may be used in combination with an appropriate curing agent to enhance the adhesive strength. The curing agent is appropriately selected from polyisocyanates, polyfunctional epoxy resins, oxazoline group-containing polymers, polyamine resins, acid anhydrides, etc. depending on the functional groups of the adhesive component.

Examples of the polyurethane adhesive include a polyurethane adhesive containing a base compound containing a polyol compound and a curing agent containing an isocyanate compound. Preferred is a two-component curing type polyurethane adhesive containing a polyol such as a polyester polyol, a polyether polyol and an acrylic polyol as a main component and an aromatic or aliphatic polyisocyanate as a curing agent. Moreover, as the polyol compound, it is preferable to use a polyester polyol having a hydroxyl group at the side chain in addition to the hydroxyl group at the terminal of the repeating unit. Since the adhesive layer 2 is formed of a polyurethane adhesive, excellent electrolytic solution resistance is imparted to the exterior material for an electricity storage device, and the base layer 1 is prevented from peeling off even when the electrolytic solution adheres to the side surface. ..

Further, the adhesive layer 2 may contain other components as long as it does not impair the adhesiveness, and may contain a colorant, a thermoplastic elastomer, a tackifier, a filler, or the like. Since the adhesive layer 2 contains the coloring agent, the exterior material for the electricity storage device can be colored. Known colorants such as pigments and dyes can be used as the colorant. Moreover, only one type of colorant may be used, or two or more types may be mixed and used.

The type of pigment is not particularly limited as long as it does not impair the adhesiveness of the adhesive layer 2. Examples of the organic pigment include azo-based pigments, phthalocyanine-based pigments, quinacridone-based pigments, anthraquinone-based pigments, dioxazine-based pigments, indigothioindigo-based pigments, perinone-perylene-based pigments, isoindolenin-based pigments, and benzimidazolone-based pigments. Examples of the pigment include carbon black pigments, titanium oxide pigments, cadmium pigments, lead pigments, chromium oxide pigments, iron pigments and the like, and mica (mica) fine powder, fish scale foil and the like.

Among the colorants, for example, carbon black is preferable in order to make the exterior material of the electricity storage device black in appearance.

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

The content of the pigment in the adhesive layer 2 is not particularly limited as long as the exterior material for the electricity storage device is colored, and for example, it is about 5 to 60% by mass, preferably 10 to 40% by mass.

The thickness of the adhesive layer 2 is not particularly limited as long as the base material layer 1 and the barrier layer 3 can be bonded, but the lower limit is, for example, about 1 μm or more and about 2 μm or more, and the upper limit is about 10 μm or less. And about 5 μm or less, and preferable ranges include about 1 to 10 μm, about 1 to 5 μm, about 2 to 10 μm, and about 2 to 5 μm, and of these, about 2 to 5 μm is particularly preferable.

[Colored layer]
The colored layer is a layer provided between the base material layer 1 and the barrier layer 3 as necessary (not shown). When the adhesive layer 2 is provided, a coloring layer may be provided between the base material layer 1 and the adhesive layer 2 and between the adhesive layer 2 and the barrier layer 3. A colored layer may be provided outside the base material layer 1. By providing the colored layer, the exterior material for the electricity storage device can be colored.

The colored layer can be formed, for example, by applying an ink containing a colorant to the surface of the base material 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 the colorant. Moreover, only one type of colorant may be used, or two or more types may be mixed and used.

Specific examples of the colorant contained in the color layer are the same as those exemplified in the section of [Adhesive layer 2].

[Barrier layer 3]
In the exterior material for an electricity storage device, the barrier layer 3 is a layer that suppresses at least entry of moisture.

Examples of the barrier layer 3 include a metal foil having a barrier property, a vapor deposition film, a resin layer, and the like. The vapor deposition film may be a metal vapor deposition film, an inorganic oxide vapor deposition film, a carbon-containing inorganic oxide vapor deposition film, or the like, and the resin layer may be polyvinylidene chloride, chlorotrifluoroethylene (CTFE)-based polymers or tetrachloride. Examples thereof include polymers containing fluoroethylene (TFE) as a main component, polymers having a fluoroalkyl group, fluorine-containing resins such as polymers having a fluoroalkyl unit as a main component, and ethylene vinyl alcohol copolymers. Further, as the barrier layer 3, a resin film provided with at least one of the vapor deposition film and the resin layer may be used. A plurality of barrier layers 3 may be provided. The barrier layer 3 preferably includes a layer made of a metal material. Specific examples of the metal material forming the barrier layer 3 include aluminum alloys, stainless steels, titanium steels, and steel plates. When used as metal foils, at least one of aluminum alloy foils and stainless steel foils is included. It is preferable.

The aluminum alloy foil is, from the viewpoint of improving the formability of the exterior material for an electricity storage device, for example, a soft aluminum alloy foil composed of annealed aluminum alloy or the like is more preferable, and the formability is further improved. Therefore, the aluminum alloy foil containing iron is preferable. In the aluminum alloy foil containing iron (100% by mass), the content of iron is preferably 0.1 to 9.0% by mass, and more preferably 0.5 to 2.0% by mass. When the iron content is 0.1% by mass or more, it is possible to obtain an outer casing material for an electricity storage device having more excellent moldability. When the iron content is 9.0 mass% or less, it is possible to obtain a more flexible outer packaging material for an electricity storage device. As the soft aluminum alloy foil, for example, an aluminum alloy having a composition defined by JIS H4160:1994 A8021H-O, JIS H4160:1994 A8079H-O, JIS H4000:2014 A8021P-O, or JIS H4000:2014 A8029P-O. Foil can be mentioned. If necessary, silicon, magnesium, copper, manganese, etc. may be added.
The softening can be performed by annealing treatment or the like.

Examples of the stainless steel foil include austenite-based, ferrite-based, austenite-ferrite-based, martensite-based, and precipitation hardening-based stainless steel foils. Further, from the viewpoint of providing an exterior material for an electricity storage device having excellent moldability, the stainless steel foil is preferably made of austenitic stainless steel.

Specific examples of the austenitic stainless steel forming the stainless steel foil include SUS304, SUS301, and SUS316L, and among these, SUS304 is particularly preferable.

In the case of a metal foil, the thickness of the barrier layer 3 may be at least a function as a barrier layer that suppresses the entry of moisture, and is, for example, about 9 to 200 μm. As for the thickness of the barrier layer 3, for example, the upper limit is preferably about 85 μm or less, more preferably about 50 μm or less, further preferably about 40 μm or less, particularly preferably about 35 μm or less, and the lower limit is preferably about. 10 μm or more, more preferably about 20 μm or more, more preferably about 25 μm or more, and the preferable range of the thickness is about 10 to 85 μm, about 10 to 50 μm, about 10 to 40 μm, about 10 to 35 μm, 20 to 20 μm. It is about 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. When the barrier layer 3 is made of an aluminum alloy foil, the above range is particularly preferable, and the range of 35 to 45 μm is particularly preferable. Further, in particular, when the barrier layer 3 is composed of a 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, further preferably about 40 μm or less, More preferably about 30 μm or less, particularly preferably about 25 μm or less, the lower limit is preferably about 10 μm or more, more preferably about 15 μm or more, and the preferable thickness range is about 10 to 60 μm. ˜50 μm, about 10-40 μm, about 10-30 μm, about 10-25 μm, about 15-60 μm, about 15-50 μm, about 15-40 μm, about 15-30 μm, about 15-25 μm.

[Corrosion resistant films 3a, 3b]
In the exterior material for an electricity storage device of the present disclosure, the barrier layer 3 is provided with a corrosion resistant film on at least one surface thereof. In the exterior material for an electricity storage device of the present disclosure, the corrosion-resistant coating 3a may be provided only on the surface of the barrier layer 3 on the heat-fusible resin layer 4 side, or the barrier layer 3 on the base material layer 1 side. The corrosion resistant coating 3b may be provided only on the surface of the barrier layer 3, or the corrosion resistant coatings 3a and 3b may be provided on both surfaces of the barrier layer 3, respectively.

In addition, in the exterior material for an electricity storage device of the present disclosure, when the corrosion resistant film is analyzed using the time-of-flight secondary ion mass spectrometry method, the peak intensity P _{CePO 4} derived from CePO ₄ ⁻ is PO ₃ ^-. The ratio P _PO3 /P _CePO4 of the peak intensity P _PO3 derived from is in the range of 80 to 120. The peak intensity ratio P _PO3 / P _CePO4, may be in the range of above, corrosion resistant coating 3a, for any of 3b, the peak intensity ratio P _PO3 / P _CePO4 may be in the range of the Is preferred. In particular, the corrosion-resistant coating 3a located on the heat-fusible resin layer side of the barrier layer and layers adjacent thereto (for example, the adhesive layer 5 and the heat-fusible resin layer 4 which are provided as necessary). ), the adhesiveness is likely to decrease due to the permeation of the electrolytic solution. Therefore, in the exterior material for an electricity storage device of the present disclosure, the corrosion-resistant coating 3a is formed on at least the surface of the barrier layer 3 on the heat-fusible resin layer 4 side. It is preferable that the peak intensity ratio P _PO3 /P _{CePO4 of} the corrosion resistant film 3a is within the above range. Regarding these points, the same applies to each peak intensity ratio shown below.

In the present disclosure, the ratio P _PO3 /P _CePO4 of the peak intensity P _PO3 derived from PO ₃ ⁻ to the peak intensity P _CePO4 derived from CePO ₄ ⁻ may be in the range of 80 to 120, but a corrosion resistant film is formed. From the viewpoint of further enhancing the adhesiveness of the barrier layer provided, the lower limit of the ratio P _PO3 /P _CePO4 is preferably about 85 or more, more preferably about 92 or more, and the upper limit is preferably about 110 or less. More preferably, it is about 105 or less, further preferably about 98 or less. The range of the peak intensity ratio P _PO3 /P _CePO4 is preferably about 80 to 110, about 80 to 105, about 80 to 98, about 85 to 120, about 85 to 110, about 85 to 105, 85. .About.98, about 92 to 120, about 92 to 110, about 92 to 105, and about 92 to 98.

The method for analyzing the corrosion resistant coatings 3a and 3b by using the time-of-flight secondary ion mass spectrometry is specifically performed by using a time-of-flight secondary ion mass spectrometer under the following measurement conditions. be able to.

(Measurement condition)
Primary ion: Double-charged bismuth cluster ion (Bi ₃ ⁺⁺ ).
Primary ion acceleration voltage: 30 kV
Mass range (m/z): 0 to 1500
Measuring range: 100 μm×100 μm
Number of scans: 16 scan/cycle
Number of pixels (1 side): 256 pixels
Etching ions: Ar gas cluster ion beam (Ar-GCIB)
Etching ion acceleration voltage: 5.0 kV

Further, the fact that the corrosion resistant film contains cerium can be confirmed by using X-ray photoelectron spectroscopy. Specifically, first, in the exterior material for an electricity storage device, the layers (adhesive layer, heat-fusible resin layer, adhesive layer, etc.) laminated on the barrier layer are physically peeled off. Next, the barrier layer is placed in an electric furnace, and the organic component existing on the surface of the barrier layer is removed at about 300° C. for about 30 minutes. After that, the presence of cerium is confirmed using X-ray photoelectron spectroscopy on the surface of the barrier layer.

The corrosion resistant coatings 3a and 3b can be formed by subjecting the surface of the barrier layer 3 to chemical conversion treatment with a treatment liquid containing a cerium compound such as cerium oxide.

As the chemical conversion treatment using a treatment liquid containing a cerium compound, for example, phosphoric acid and/or its salt in which a cerium compound such as cerium oxide is dispersed is applied to the surface of the barrier layer 3 and baked. A method of forming a corrosion resistant film on the surface of the barrier layer 3 by carrying out the method can be mentioned.

The peak intensity ratio P _PO3 /P _CePO4 of the corrosion resistant coatings 3a and 3b _depends on, for example, the composition of the treatment liquid forming the corrosion resistant coatings 3a and 3b, the manufacturing conditions such as the temperature and time of the baking treatment after the treatment. Can be adjusted.

The ratio of the cerium compound to the phosphoric acid and/or its salt in the treatment liquid containing the cerium compound is not particularly limited, but from the viewpoint of setting the peak intensity ratio P _PO3 /P _CePO4 within the above range, cerium is used. The ratio of phosphoric acid and/or its salt with respect to 100 parts by mass of the compound is preferably about 12 to 28, more preferably about 15 to 25 parts by mass. As the phosphoric acid and its salt, for example, condensed phosphoric acid and its salt can also be used.

The treatment liquid containing the cerium compound may further contain an anionic polymer and a crosslinking agent for crosslinking the anionic polymer. Examples of the anionic polymer include poly(meth)acrylic acid or a salt thereof, a copolymer containing (meth)acrylic acid or a salt thereof as a main component, and the like. Examples of the cross-linking agent include compounds having a functional group of any one of an isocyanate group, a glycidyl group, a carboxyl group and an oxazoline group, and a silane coupling agent. The anionic polymer and the cross-linking agent may each be one type or two or more types.

Further, from the viewpoint of enhancing the adhesion of the barrier layer provided with the corrosion resistant film while exhibiting excellent corrosion resistance, it is preferable that the treatment liquid containing the cerium compound contains an aminated phenol polymer. In the treatment liquid containing a cerium compound, the content of the aminated phenol polymer is preferably about 100 to 400 parts by mass, more preferably about 200 to 300 parts by mass, relative to 100 parts by mass of the cerium compound. The weight average molecular weight of the aminated phenol polymer is preferably about 5,000 to 20,000. The weight average molecular weight of the aminated phenol polymer is a value measured by gel permeation chromatography (GPC), which was measured under the condition that polystyrene was used as a standard sample.

The solvent for the treatment liquid containing the cerium compound is not particularly limited as long as it can disperse the components contained in the treatment liquid and is then evaporated by heating, but water is preferable. The solid concentration of the treatment liquid containing the cerium compound is, for example, about 8 to 30% by mass.

The solid content concentration of the cerium compound contained in the treatment liquid for forming the corrosion resistant film is not particularly limited, but the peak strength ratio P _PO3 /P _{CePO 4} is set in the above predetermined range to obtain excellent corrosion resistance. From the viewpoint of enhancing the adhesion of the barrier layer provided with the corrosion-resistant film while exhibiting the above, it is preferably about 9.0 to 10.0 parts by mass with respect to 100 parts by mass of the solvent (such as water), More preferably, it is about 9.1 to 10.0 parts by mass.

The thickness of the corrosion resistant film is not particularly limited, but from the viewpoint of enhancing the adhesion of the barrier layer provided with the corrosion resistant film while exhibiting excellent corrosion resistance, it is preferably about 1 nm to 10 μm, more preferably The thickness is preferably about 1 to 100 nm, more preferably about 1 to 50 nm. The thickness of the corrosion-resistant coating can be measured by observation with a transmission electron microscope, or a combination of observation with a transmission electron microscope and energy dispersive X-ray spectroscopy or electron beam energy loss spectroscopy.

From the same viewpoint, the amount of the corrosion resistant coating per 1 m ² of the surface of the barrier layer 3 is preferably about 2 to 100 mg, more preferably about 2 to 70 mg, and further preferably about 2 to 40 mg.

Examples of methods for applying the treatment liquid to the surface of the barrier layer 3 include a bar coating method, a roll coating method, a gravure coating method, and a dipping method.

By setting the peak intensity ratio P _PO3 /P _CePO4 to the above predetermined ranges, respectively, from the viewpoint of enhancing the adhesion of the barrier layer provided with the corrosion resistant film while exhibiting excellent corrosion resistance, the treatment liquid is The heating temperature at the time of baking to form a corrosion resistant film is preferably about 170 to 250°C, more preferably about 180 to 220°C, and further preferably about 190 to 220°C. From the same viewpoint, the baking time is preferably about 2 to 10 seconds, more preferably about 3 to 6 seconds.

From the viewpoint of more efficiently performing the chemical conversion treatment on the surface of the barrier layer, before forming the corrosion resistant film on the surface of the barrier layer 3, an alkali dipping method, an electrolytic cleaning method, an acid cleaning method, an electrolytic acid cleaning method, an acid is used. Degreasing treatment is preferably performed by a known treatment method such as an activation method.

[The heat-fusible resin layer 4]
In the exterior material for an electricity storage device of the present disclosure, the heat-fusible resin layer 4 corresponds to the innermost layer, and the heat-fusible resin layers are heat-fused to each other during assembly of the electricity storage device to seal the electricity storage device element. It is a layer (sealant layer) that exerts.

The resin constituting the heat-fusible resin layer 4 is not particularly limited as long as it can be heat-bonded, but a resin containing a polyolefin skeleton such as polyolefin or acid-modified polyolefin is preferable. The fact that the resin constituting the heat-fusible resin layer 4 contains a polyolefin skeleton can be analyzed by, for example, infrared spectroscopy, gas chromatography mass spectrometry, or the like. Further, when the resin forming the heat-fusible resin layer 4 is analyzed by infrared spectroscopy, it is preferable that a peak derived from maleic anhydride is detected. For example, when measuring the infrared spectroscopy at a maleic anhydride-modified polyolefin, a peak derived from maleic acid is detected in the vicinity of the wave number of 1760 cm ^-1 and near the wave number 1780 cm ^-1. When the heat-fusible resin layer 4 is a layer composed of a maleic anhydride-modified polyolefin, a peak derived from maleic anhydride is detected when measured by infrared spectroscopy. However, if the degree of acid modification is low, the peak may be too small to be detected. In that case, it can be analyzed by nuclear magnetic resonance spectroscopy.

Specific examples of the polyolefin include polyethylene such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; ethylene-α olefin copolymers; homopolypropylene, polypropylene block copolymers (for example, propylene and Examples thereof include polypropylene block copolymers) and polypropylene random copolymers (for example, random copolymers of propylene and ethylene); propylene-α-olefin copolymers; 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.

Further, the polyolefin may be a cyclic polyolefin. The cyclic polyolefin is a copolymer of an olefin and a cyclic monomer, and examples of the olefin which is a constituent monomer of the cyclic polyolefin include ethylene, propylene, 4-methyl-1-pentene, styrene, butadiene, and isoprene. To be Examples of the cyclic monomer which is a constituent monomer of the cyclic polyolefin include cyclic alkenes such as norbornene; and cyclic dienes such as cyclopentadiene, dicyclopentadiene, cyclohexadiene and norbornadiene. Of these, cyclic alkenes are preferable, and norbornene is more preferable.

The acid-modified polyolefin is a polymer modified by block-polymerizing or graft-polymerizing a polyolefin with an acid component. As the acid-modified polyolefin, the above-mentioned polyolefin, a copolymer obtained by copolymerizing the above-mentioned polyolefin with a polar molecule such as acrylic acid or methacrylic acid, or a polymer such as a cross-linked polyolefin can be used. Examples of the acid component used for acid modification include carboxylic acids such as maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, and itaconic anhydride, or anhydrides thereof.

The acid-modified polyolefin may be an acid-modified cyclic polyolefin. The acid-modified cyclic polyolefin is a polymer obtained by copolymerizing part of the monomers constituting the cyclic polyolefin in place of the acid component, or by block-polymerizing or graft-polymerizing the acid component with respect to the cyclic polyolefin. is there. 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, polypropylene modified with carboxylic acids or their anhydrides, maleic anhydride-modified polyolefins, maleic anhydride-modified polypropylenes.

The heat-fusible resin layer 4 may be formed of one type of resin alone, or may be formed of a blend polymer in which two or more types of resins are combined. Further, the heat-fusible resin layer 4 may be formed of only one layer, but may be formed of two or more layers of the same or different resin.

In addition, the heat-fusible resin layer 4 may include a lubricant and the like, if necessary. When the heat-fusible resin layer 4 contains a lubricant, the moldability of the exterior material for an electricity storage device can be improved. The lubricant is not particularly limited, and a known lubricant can be used. The lubricant may be used singly or in combination of two or more.

The lubricant is not particularly limited, but preferably an amide lubricant is used. Specific examples of the lubricant include those exemplified for the base material layer 1. The lubricant may be used alone or in combination of two or more.

When a lubricant is present on the surface of the heat-fusible resin layer 4, the amount of the lubricant is not particularly limited, but from the viewpoint of enhancing the moldability of the exterior material for an electricity storage device, it is preferably about 10 to 50 mg/m ^2. And more preferably about 15 to 40 mg/m ² .

The lubricant present on the surface of the heat-fusible resin layer 4 may be one in which the lubricant contained in the resin forming the heat-fusible resin layer 4 is exuded, or The surface may be coated with a lubricant.

The thickness of the heat-fusible resin layer 4 is not particularly limited as long as the heat-fusible resin layers have a function of heat-sealing each other and sealing the electricity storage device element, but for example, about 100 μm or less, preferably The thickness is about 85 μm or less, more preferably about 15 to 85 μm. For example, when the thickness of the adhesive layer 5 described later is 10 μm or more, the thickness of the heat-fusible resin layer 4 is preferably about 85 μm or less, about 25 to 35 μm, about 50 to 60 μm, and the like. .. More specifically, when the thickness of the adhesive layer 5 is set to about 12 to 18 μm, the thickness of the heat-fusible resin layer 4 is considered in consideration of the balance of the laminated structure of the exterior material 10 for an electricity storage device. Is preferably about 25 to 35 μm, and when the thickness of the adhesive layer 5 is set to about 22 to 28 μm, the thickness of the heat-fusible resin layer 4 is preferably set to about 50 to 60 μm. .. For example, when the thickness of the adhesive layer 5 described below is less than 10 μm or when the adhesive layer 5 is not provided, the thickness of the heat-fusible resin layer 4 is preferably about 20 μm or more, and more preferably The thickness is about 35 to 85 μm.

[Adhesive layer 5]
In the exterior material for an electricity storage device of the present disclosure, the adhesive layer 5 is provided between the barrier layer 3 (or the corrosion-resistant coating 3a) and the heat-fusible resin layer 4 in order to firmly bond the barrier layer 3 (or the corrosion-resistant film 3a) to each other, if necessary. It is a layer provided.

The adhesive layer 5 is formed of a resin capable of adhering the barrier layer 3 (or the corrosion resistant film 3a) and the heat-fusible resin layer 4 to each other. As the resin used for forming the adhesive layer 5, for example, the same adhesives as those exemplified for the adhesive layer 2 can be used. The resin used for forming the adhesive layer 5 preferably contains a polyolefin skeleton, and examples thereof include the polyolefins and the acid-modified polyolefins exemplified in the above heat-fusible resin layer 4. The fact that the resin constituting the adhesive layer 5 contains a polyolefin skeleton can be analyzed by, for example, infrared spectroscopy, gas chromatography mass spectrometry, etc., and the analysis method is not particularly limited. In addition, when the resin constituting the adhesive layer 5 is analyzed by infrared spectroscopy, it is preferable that a peak derived from maleic anhydride is detected. For example, when measuring the infrared spectroscopy at a maleic anhydride-modified polyolefin, a peak derived from maleic acid is detected in the vicinity of the wave number of 1760 cm ^-1 and near the wave number 1780 cm ^-1. However, if the degree of acid modification is low, the peak may be too small to be detected. In that case, it can be analyzed by nuclear magnetic resonance spectroscopy.

From the viewpoint of firmly adhering the barrier layer 3 (or the corrosion resistant film 3a) and the heat-fusible resin layer 4, the adhesive layer 5 preferably contains an acid-modified polyolefin. As the acid-modified polyolefin, a polyolefin modified with a carboxylic acid or an anhydride thereof, a polypropylene modified with a carboxylic acid or an anhydride thereof, a maleic anhydride modified polyolefin, and a maleic anhydride modified polypropylene are particularly preferable.

Furthermore, from the viewpoint of making the exterior material for an electricity storage device thinner while also providing an exterior material for an electricity storage device having excellent shape stability after molding, the adhesive layer 5 is a resin composition containing an acid-modified polyolefin and a curing agent. It is more preferable that the cured product is. As the acid-modified polyolefin, those mentioned above can be preferably exemplified.

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

Further, from the viewpoint of further improving the adhesiveness between the barrier layer 3 (or the corrosion resistant film 3a) and the adhesive layer 5, the adhesive layer 5 includes an oxygen atom, a heterocycle, a C═N bond, and a C—O—C bond. It is preferably a cured product of a resin composition containing a curing agent having at least one selected from the group consisting of Examples of the curing agent having a heterocycle include a curing agent having an oxazoline group and a curing agent having an epoxy group. Examples of the curing agent having a C=N bond include a curing agent having an oxazoline group and a curing agent having an isocyanate group. Further, examples of the curing agent having a C—O—C bond include a curing agent having an oxazoline group, a curing agent having an epoxy group, and polyurethane. The fact that the adhesive layer 5 is a cured product of a resin composition containing these curing agents means, for example, gas chromatograph mass spectrometry (GCMS), infrared spectroscopy (IR), time-of-flight secondary ion mass spectrometry (TOF). -SIMS), X-ray photoelectron spectroscopy (XPS) and the like.

The compound having an isocyanate group is not particularly limited, but from the viewpoint of effectively enhancing the adhesion between the barrier layer 3 (or the corrosion resistant film 3a) and the adhesive layer 5, a polyfunctional isocyanate compound is preferable. .. The polyfunctional isocyanate compound is not particularly limited as long as it is a compound having two or more isocyanate groups. Specific examples of the polyfunctional isocyanate-based curing agent include pentane diisocyanate (PDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), and polymerization or nurate thereof. And the like, and mixtures thereof and copolymers with other polymers. Moreover, an adduct body, a burette body, an isocyanurate body, etc. are mentioned.

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 0.5 to 40% by mass in the resin composition constituting the adhesive layer 5. More preferably, it is in the range. Thereby, the adhesiveness between the barrier layer 3 (or the corrosion resistant film 3a) and the adhesive layer 5 can be effectively enhanced.

The compound having an oxazoline group is not particularly limited as long as it is a compound having an oxazoline skeleton. Specific examples of the compound having an oxazoline group include those having a polystyrene main chain and those having an acrylic main chain. Examples of commercially available products include Epocros 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% by mass, and in the range of 0.5 to 40% by mass in the resin composition constituting the adhesive layer 5. Is more preferable. Thereby, the adhesiveness between the barrier layer 3 (or the corrosion resistant film 3a) and the adhesive layer 5 can be effectively enhanced.

Examples of compounds having an epoxy group include epoxy resins. The epoxy resin is not particularly limited as long as it is a resin capable of forming a crosslinked structure by an epoxy group existing in the molecule, and a known epoxy resin can be used. The weight average molecular weight of the epoxy resin is preferably about 50 to 2000, more preferably about 100 to 1000, and further preferably about 200 to 800. In the present disclosure, the weight average molecular weight of the epoxy resin is a value measured by gel permeation chromatography (GPC), which is measured under the condition that polystyrene is used as a standard sample.

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

The proportion of the epoxy resin in the adhesive layer 5 is preferably in the range of 0.1 to 50% by mass, and in the range of 0.5 to 40% by mass in the resin composition constituting the adhesive layer 5. Is more preferable. Thereby, the adhesiveness between the barrier layer 3 and the adhesive layer 5 can be effectively enhanced.

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

The proportion of polyurethane in the adhesive layer 5 is preferably in the range of 0.1 to 50% by mass, and in the range of 0.5 to 40% by mass in the resin composition constituting the adhesive layer 5. More preferable. Thereby, the adhesiveness between the barrier layer 3 (or the corrosion resistant film 3a) and the adhesive layer 5 can be effectively enhanced in an atmosphere in which a component that induces corrosion of the barrier layer such as an electrolytic solution exists.

When the 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 main agent, 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 the adhesive layer 5 is preferably about 50 μm or less, about 40 μm or less, about 30 μm or less, about 20 μm or less, about 5 μm or less, and the lower limit is preferably about 0.1 μm or more. , About 0.5 μm or more, and the thickness range is preferably about 0.1 to 50 μm, about 0.1 to 40 μm, about 0.1 to 30 μm, about 0.1 to 20 μm, 0. 1 to 5 μm, 0.5 to 50 μm, 0.5 to 40 μm, 0.5 to 30 μm, 0.5 to 20 μm, and 0.5 to 5 μm. More specifically, in the case of the adhesive exemplified in the adhesive layer 2 or a cured product of an acid-modified polyolefin and a curing agent, it is preferably about 1 to 10 μm, more preferably about 1 to 5 μm. When the resin exemplified in the heat-fusible resin layer 4 is used, it is preferably about 2 to 50 μm, about 10 to 40 μm, about 12 to 18 μm, about 22 to 28 μm. As described above, when the thickness of the adhesive layer 5 is set to about 12 to 18 μm, the thickness of the heat-fusible resin layer 4 is 25 in consideration of the balance of the laminated structure of the exterior material 10 for an electricity storage device. The thickness of the heat-fusible resin layer 4 is preferably set to about 50 to 60 μm when the thickness of the adhesive layer 5 is set to about 22 to 28 μm. When the adhesive layer 5 is a cured product of the adhesive exemplified in the adhesive layer 2 or a resin composition containing an acid-modified polyolefin and a curing agent, for example, the resin composition is applied and cured by heating or the like. As a result, the adhesive layer 5 can be formed. When the resin exemplified in the heat-fusible resin layer 4 is used, the heat-fusible resin layer 4 and the adhesive layer 5 can be formed by extrusion molding, for example.

[Surface coating layer 6]
The exterior material for an electricity storage device of the present disclosure is, if necessary, on the base material layer 1 (base material layer 1 for the purpose of at least one of improvement in designability, electrolytic solution resistance, scratch resistance, moldability, etc.). The surface coating layer 6 may be provided on the side opposite to the barrier layer 3). The surface coating layer 6 is a layer located on the outermost layer side of the exterior material for an electricity storage device when the electricity storage device is assembled using the exterior material for an electricity storage device.

The surface coating layer 6 can be formed of 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 curing type or a two-component curing type, but is preferably a two-component curing type. Examples of the two-component curing type resin include two-component curing type polyurethane, two-component curing type polyester, and two-component curing type epoxy resin. Of these, two-component curing type polyurethane is preferable.

Examples of the two-component curable polyurethane include polyurethane containing a base compound containing a polyol compound and a curing agent containing an isocyanate compound. Preferred is a two-component curing type polyurethane having a polyol such as a polyester polyol, a polyether polyol, and an acrylic polyol as a main component and an aromatic or aliphatic polyisocyanate as a curing agent. Moreover, as the polyol compound, it is preferable to use a polyester polyol having a hydroxyl group at the side chain in addition to the hydroxyl group at the terminal of the repeating unit. Since the surface coating layer 6 is made of polyurethane, excellent electrolytic solution resistance is imparted to the exterior material for an electricity storage device.

The surface coating layer 6 may be provided on at least one of the surface and the inside of the surface coating layer 6 depending on the surface coating layer 6 and the functionality to be provided on the surface, and if necessary, the above-mentioned lubricant or anti-reflective agent. It may contain additives such as a blocking agent, a matting agent, a flame retardant, an antioxidant, a tackifier, and an antistatic agent. Examples of the additive include fine particles having an average particle diameter of about 0.5 nm to 5 μm. The average particle size of the additive is the median size measured by a laser diffraction/scattering type particle size distribution measuring device.

The additive may be either an inorganic substance or an organic substance. Also, the shape of the additive is not particularly limited, and examples thereof include spherical shape, fibrous shape, plate shape, amorphous shape, and scale shape.

Specific examples of the additive 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, Examples include crosslinked acrylic, crosslinked styrene, crosslinked polyethylene, benzoguanamine, gold, aluminum, copper and nickel. The additives may be used alone or in combination of two or more. Among these additives, silica, barium sulfate and titanium oxide are preferable from the viewpoint of dispersion stability and cost. The additives may be subjected to various surface treatments such as insulation treatment and high dispersibility treatment on the surface.

The method of forming the surface coating layer 6 is not particularly limited, and examples thereof include a method of applying a resin forming the surface coating layer 6. When the surface coating layer 6 is mixed with an additive, 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 as the surface coating layer 6, and is, for example, about 0.5 to 10 μm, preferably about 1 to 5 μm.

3. The preparation method of the production method for an electricity storage device exterior material of the outer package for a power storage device, as long as the laminate exterior material for a power storage device of the present disclosure a laminate of layers included in the obtained, not particularly limited, at least, the substrate The method includes a step of laminating the layer 1, the barrier layer 3, and the heat-fusible resin layer 4 in this order. That is, in the method for manufacturing the exterior material for an electricity storage device of the present disclosure, at least the base material layer 1, the barrier layer 3, and the heat-fusible resin layer 4 are laminated in this order to obtain a laminate. The substrate layer 1 is composed of a single-layer polyester film, and the surface of at least one side of the barrier layer 3 is provided with a corrosion resistant film. When analyzed using time-of-flight secondary ion mass spectrometry, the ratio P _PO3 /P _{CePO4 of} the peak intensity P _PO3 derived from PO ₃ ⁻ to the peak intensity P _CePO4 derived from CePO ₄ ⁻ is 80 or more and 120 or more. It is characterized by being in the following range.

The following is an example of the method for manufacturing the exterior material for an electricity storage device of the present disclosure. First, a laminated body (hereinafter, also referred to as “laminated body A”) in which a base material layer 1, an adhesive layer 2, and a barrier layer 3 having a corrosion resistant film on at least one surface thereof are laminated in order is described. Form. To form the laminate A, specifically, the adhesive used for forming the adhesive layer 2 on the barrier layer 3 on the base material layer 1 or the surface of which is subjected to a chemical conversion treatment is formed by a gravure coating method, a roll coating method, or the like. It can be carried out by a dry laminating method in which the barrier layer 3 or the base material layer 1 is laminated and the adhesive layer 2 is cured after being coated and dried by the coating method.

Next, the heat-fusible resin layer 4 is laminated on the barrier layer 3 of the laminate A. When the heat-fusible resin layer 4 is directly laminated on the barrier layer 3, the heat-fusible resin layer 4 is laminated on the barrier layer 3 of the laminate A by a method such as a thermal laminating method or an extrusion laminating method. do it. When the adhesive layer 5 is provided between the barrier layer 3 and the heat-fusible resin layer 4, for example, (1) the adhesive layer 5 and the heat-fusible resin layer are provided on the barrier layer 3 of the laminate A. Method of laminating by extruding 4 (coextrusion laminating method, tandem laminating method), (2) Separately, a laminated body in which the adhesive layer 5 and the heat-fusible resin layer 4 are laminated is formed, and the laminated body A By a thermal lamination method, or by forming a laminated body in which the adhesive layer 5 is laminated on the barrier layer 3 of the laminated body A by using the thermal fusion bonding resin layer 4 and the thermal lamination method. Method of Laminating, (3) Through the adhesive layer 5 while pouring the melted adhesive layer 5 between the barrier layer 3 of the laminate A and the heat-fusible resin layer 4 which is formed into a sheet in advance. The laminate A and the heat-fusible resin layer 4 are bonded together (sandwich laminating method), (4) the barrier layer 3 of the laminate A is solution-coated with an adhesive for forming the adhesive layer 5, Examples thereof include a method of drying, a method of baking, and a method of laminating the heat-fusible resin layer 4 formed in a sheet shape on the adhesive layer 5 in advance.

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

As described above, the surface coating layer 6/the base material layer 1/if necessary, the adhesive layer 2/if necessary, the barrier layer 3 provided with a corrosion resistant film on at least one surface thereof/necessary A laminated body including the adhesive layer 5/the heat-fusible resin layer 4 provided in this order is formed. In order to strengthen the adhesiveness of the adhesive layer 2 provided as necessary, It may be subjected to heat treatment.

In the exterior material for an electricity storage device, each layer constituting the laminate may be subjected to surface activation treatment such as corona treatment, blast treatment, oxidation treatment, or ozone treatment, if necessary, to improve processability. .. For example, by performing corona treatment on the surface of the base material layer 1 opposite to the barrier layer 3, the printability of the ink on the surface of the base material layer 1 can be improved.

4. Application of Exterior Material for Electric Storage Device The exterior material for an electric storage device according to the present disclosure is used for a package for hermetically housing an electric storage device element such as a positive electrode, a negative electrode, and an electrolyte. That is, an electricity storage device can be prepared by accommodating an electricity storage device element including at least a positive electrode, a negative electrode, and an electrolyte in a package formed of the exterior material for an electricity storage device of the present disclosure. In addition, in the exterior material for an electricity storage device of the present disclosure, the peak intensity and the like can be analyzed by cutting the exterior material for an electricity storage device from the electricity storage device. When cutting the exterior material for an electricity storage device from the electricity storage device, a sample is obtained from a portion where the heat-fusible resin layers are not thermally fused to each other, such as a top surface or a bottom surface of the electricity storage device, and used for analysis.

Specifically, in an electricity storage device element having at least a positive electrode, a negative electrode, and an electrolyte, in the exterior material for an electricity storage device of the present disclosure, with the metal terminals connected to each of the positive electrode and the negative electrode protruding outward. To cover the periphery of the electricity storage device element so that a flange portion (a region where the heat-fusible resin layers contact each other) can be formed, and heat-seal the heat-fusible resin layers of the flange portion to hermetically seal them. Thus, an electricity storage device using the exterior material for an electricity storage device is provided. In the case where the electricity storage device element is housed in a package formed of the electricity storage device exterior material of the present disclosure, the heat-fusible resin portion of the electricity storage device exterior material of the present disclosure is inside (a surface that contacts the electricity storage device element). ), and a package is formed.

The packaging material for an electricity storage device according to the present disclosure may be used in either a primary battery or a secondary battery, but is preferably a secondary battery. The type of secondary battery to which the exterior material for an electricity storage device of the present disclosure is applied is not particularly limited, and examples thereof include lithium ion batteries, lithium ion polymer batteries, lead storage batteries, nickel-hydrogen storage batteries, nickel-cadmium storage batteries, and nickel. -Iron storage batteries, nickel-zinc storage batteries, silver oxide-zinc storage batteries, metal-air batteries, polyvalent cation batteries, capacitors, capacitors and the like. Among these secondary batteries, lithium ion batteries and lithium ion polymer batteries are mentioned as suitable targets to which the battery exterior material of the present disclosure is applied.

In the exterior material for an electricity storage device of the present disclosure, the barrier layer provided with the corrosion resistant film can maintain the adhesiveness for a long period of time. Therefore, the exterior material for an electricity storage device of the present disclosure is particularly useful as an exterior material for a large electricity storage device used in vehicles such as hybrid vehicles and electric vehicles.

Hereinafter, the present disclosure will be described in detail with reference to Examples and Comparative Examples. However, the present disclosure is not limited to the examples.

<Manufacture of exterior materials for power storage devices>
Example 1
A biaxially oriented polyethylene terephthalate film (PET film, thickness 25 μm) was prepared as a base material layer. Next, a chemical conversion treatment is applied to both surfaces by a method described below to form a barrier layer composed of an aluminum alloy foil (JIS H4160:1994 A8021H-O, thickness 40 μm) having a corrosion resistant film (thickness 20 nm). Then, it was laminated on the surface of the base material layer by a dry laminating method. Specifically, a two-component urethane adhesive (polyol compound and aromatic isocyanate-based compound) is applied to one surface of an aluminum alloy foil provided with a corrosion resistant film to form an adhesive layer (thickness 3 μm). did. Then, after laminating the adhesive layer on the barrier layer provided with a corrosion-resistant film and the base material layer, aging treatment is carried out to make the biaxially stretched polyethylene terephthalate film/adhesive layer/corrosion resistant on both sides. A laminate of barrier layers with a coating was prepared.

Next, on the surface of the corrosion-resistant film of the obtained laminate, maleic anhydride-modified polypropylene as an adhesive layer and random polypropylene as a heat-fusible resin layer were coextruded to give an adhesive layer (thickness 15 μm) and a heat-fusible resin layer (thickness 30 μm) were laminated. Next, by aging the obtained laminate, a biaxially stretched polyethylene terephthalate film (base material layer 25 μm)/adhesive layer (3 μm)/barrier layer (40 μm) provided with a corrosion resistant film (20 nm) on both sides. )/Acid-modified polypropylene (adhesive layer 15 μm)/random polypropylene (heat-fusible resin layer 30 μm) were laminated in this order to obtain a packaging material for an electricity storage device.

The corrosion-resistant film on the surface of the barrier layer is a treatment liquid containing 20 parts by mass of an inorganic phosphorus compound (sodium phosphate) with respect to 100 parts by mass of cerium oxide (containing water as a solvent, solid content). (Concentration is about 10% by mass), the treatment liquid is applied to both sides of the barrier layer (film thickness after drying is 20 nm), and the surface temperature of the barrier layer is about 190° C. for about 3 seconds. It was formed by heating and drying.

Example 2
In Example 1, a biaxially stretched polyethylene terephthalate film/adhesive layer/on the surface of the corrosion-resistant coating of a laminate of barrier layers having corrosion-resistant coatings on both sides, maleic anhydride-modified polypropylene as an adhesive layer, As in Example 1, except that the adhesive layer (thickness: 25 μm) and the heat-fusible resin layer (thickness: 55 μm) were laminated by coextruding a random polypropylene as the heat-fusible resin layer. Biaxially stretched polyethylene terephthalate film (base material layer 25 μm)/adhesive layer (3 μm)/barrier layer (40 μm) with corrosion resistant coating (20 nm) on both sides/acid-modified polypropylene (adhesive layer 25 μm)/random An outer packaging material for an electricity storage device was obtained in which polypropylene (a heat-fusible resin layer 55 μm) was laminated in this order. The aluminum alloy foil as the barrier layer had the same corrosion-resistant coating as in Example 1.

Comparative Example 1
An aluminum alloy foil (JIS H4160) provided with a corrosion-resistant coating (thickness: 20 nm) containing chromium on the surface of a biaxially stretched nylon film (25 μm) as a base material layer by chemical conversion treatment on both surfaces by the method described below. : 1994 A8021H-O, thickness 40 μm) was laminated by a dry laminating method. Specifically, a two-component urethane adhesive (polyol compound and aromatic isocyanate-based compound) is applied to one surface of an aluminum alloy foil provided with a corrosion resistant film to form an adhesive layer (thickness 3 μm). did. Then, after laminating the adhesive layer on the barrier layer provided with the corrosion-resistant film and the biaxially stretched nylon film as the base material layer, the aging treatment is performed to carry out biaxially stretched nylon film/adhesive layer/ A laminate of barrier layers with corrosion resistant coatings on both sides was prepared.

Next, on the surface of the corrosion resistant film of the obtained laminate, an adhesive (thickness after curing is 3 μm) composed of an amorphous polyolefin resin having a carboxyl group and a polyfunctional isocyanate compound is applied as an adhesive layer. And dried. On the adhesive side of the laminate, an unstretched laminated polypropylene film (random polypropylene (thickness 4 μm)/block polypropylene (thickness 22 μm)/random polypropylene (thickness 4 μm) as a first heat-fusible resin layer, A total thickness of 30 μm) was laminated and passed between two heated rolls for adhesion. Further, a random polypropylene (thickness 20 μm) as a second heat-fusible resin layer is extruded from thereover to laminate the adhesive layer/heat-fusible resin layer (2 layers) on the barrier layer. It was Next, by aging the obtained laminate, a biaxially stretched nylon film (25 μm)/adhesive layer (3 μm)/barrier layer (40 μm)/corrosion resistant film (thickness 20 nm) provided on both sides/ An outer packaging material for an electricity storage device was obtained in which an adhesive layer (3 μm)/unstretched laminated polypropylene film (30 μm)/random polypropylene (20 μm) were laminated in this order.

The formation of the corrosion resistant film on the surface of the barrier layer was performed as follows. A treatment solution containing 43 parts by weight of aminated phenol polymer, 16 parts by weight of chromium fluoride, and 13 parts by weight of phosphoric acid per 100 parts by weight of water was easily prepared, and the treatment solution was applied to both surfaces of the barrier layer (after drying). And the barrier layer has a surface temperature of about 190° C. for about 3 seconds.

Comparative example 2
As the heat-fusible resin layer, a biaxially stretched nylon film (25 μm)/25 μm was prepared in the same manner as in Comparative Example 1 except that random polypropylene (thickness 50 μm) was extruded instead of random polypropylene (thickness 20 μm). Adhesive layer (3 μm)/barrier layer (40 μm) with corrosion resistant coating (thickness 20 nm) on both sides/adhesive layer (3 μm)/unstretched laminated polypropylene film (30 μm)/random polypropylene (50 μm) An outer packaging material for an electricity storage device was obtained by being sequentially laminated. The aluminum alloy foil as the barrier layer had the same corrosion-resistant coating as in Comparative Example 1.

Comparative Examples 3 and 4
As the base material layer, a biaxially stretched laminated film was prepared in which polyethylene terephthalate and nylon were laminated by coextrusion. A resin containing a modified thermoplastic resin graft-modified with an unsaturated carboxylic acid derivative component between the biaxially stretched polyethylene terephthalate film (thickness 5 μm) and the biaxially stretched nylon film (thickness 20 μm) in the laminated film. It is adhered by an adhesive layer (adhesive, thickness 1 μm) using the composition. Next, a chemical conversion treatment is applied to both surfaces by a method described below to form a barrier layer composed of an aluminum alloy foil (JIS H4160:1994 A8021H-O, thickness 40 μm) having a corrosion resistant film (thickness 20 nm). It was laminated on the surface of the biaxially stretched nylon film side by a dry lamination method. Specifically, a two-component urethane adhesive (polyol compound and aromatic isocyanate-based compound) is applied to one surface of an aluminum alloy foil provided with a corrosion resistant film to form an adhesive layer (thickness 3 μm). did. Then, the biaxially stretched nylon terephthalate film/adhesive is prepared by laminating the adhesive layer on the barrier layer provided with the corrosion resistant film and the biaxially stretched nylon film side of the base material layer, and then performing aging treatment. A biaxially oriented nylon film/adhesive layer/barrier layer laminate having corrosion resistant coatings on both sides was prepared.

Next, on the surface of the corrosion resistant film of the obtained laminate, an adhesive (thickness after curing is 3 μm) composed of an amorphous polyolefin resin having a carboxyl group and a polyfunctional isocyanate compound is applied as an adhesive layer. And dried. On the adhesive side of the laminate, an unstretched laminated polypropylene film (random polypropylene (thickness 5 μm)/block polypropylene (thickness 30 μm)/random polypropylene (thickness 5 μm) as a heat-fusible resin layer, total thickness 40 μm) was laminated and passed between two heated rolls for adhesion to laminate the adhesive layer/heat-fusible resin layer on the barrier layer. Next, by curing (aging) the obtained laminate, a biaxially stretched polyethylene terephthalate film (5 μm)/adhesive (1 μm)/biaxially stretched nylon film (20 μm)/adhesive layer (3 μm)/both sides A barrier material (40 μm) provided with a corrosion-resistant coating (thickness 20 nm)/adhesive layer (3 μm)/unstretched laminated polypropylene film (40 μm) was laminated in this order to obtain a packaging material for an electricity storage device.

The corrosion-resistant coating on the surface of the barrier layer was obtained by comparing the formation of the corrosion-resistant coating on the surface of the barrier layer with phosphoric acid in Comparative Example 3 to about half (mass ratio) of Example 1 and phosphoric acid in Comparative Example 4. Was obtained in the same manner as in Example 1 except that the above was performed at about 1.5 times (mass ratio) that of Example.

<Time-of-flight secondary ion mass spectrometry>
The analysis of the corrosion resistant film was performed as follows. First, the barrier layer and the adhesive layer were peeled off. At this time, physical peeling was performed without using water, an organic solvent, an acid or alkali aqueous solution, or the like. After peeling between the barrier layer and the adhesive layer, since the adhesive layer remained on the surface of the barrier layer, the remaining adhesive layer was removed by etching with Ar-GCIB. The surface of the barrier layer thus obtained was analyzed for a corrosion resistant film by using a time-of-flight secondary ion mass spectrometry. Each CePO ₄ ^- and PO ₃ ^- and from peak intensity P _CePO4 and P _PO3, the ratio P _PO3 / P _CePO4 peak intensity P _PO3 to the peak intensity P _CePO4, respectively, shown in Table 1. In Comparative Examples 1 and 2, since chromium is used in the chemical conversion treatment solution and cerium is not used, Table 1 shows “−” for items related to the peak intensity P _CePO4 of CePO ₄ ^−. It showed with.

The details of the measuring device and the measuring conditions of the time-of-flight secondary ion mass spectrometry are as follows.
Measuring device: Time-of-flight secondary ion mass spectrometer TOF. manufactured by ION-TOF. SIMS5 (measurement condition)
Primary ion: Double-charged bismuth cluster ion (Bi ₃ ⁺⁺ ).
Primary ion acceleration voltage: 30 kV
Mass range (m/z): 0 to 1500
Measuring range: 100 μm×100 μm
Number of scans: 16 scan/cycle
Number of pixels (1 side): 256 pixels
Etching ions: Ar gas cluster ion beam (Ar-GCIB)
Etching ion acceleration voltage: 5.0 kV

<Adhesion evaluation>
By the following method, the adhesion between the barrier layer and the heat-fusible resin layer when the electrolytic solution adheres to the exterior material for an electricity storage device is evaluated by measuring the peel strength (N/15 mm). It was

First, each of the exterior materials for electric storage devices obtained above was cut into a test piece by cutting into a size of 15 mm (TD: Transverse Direction, lateral direction) and 100 mm (MD: Machine Direction, longitudinal direction). A test piece was placed in a glass bottle, and further mixed with an electrolytic solution (ethylene carbonate:diethyl carbonate:dimethyl carbonate=1:1:1 in volume ratio, to a solution of lithium hexafluorophosphate (concentration in the solution: 1×10 ³ mol/m 2. ³ )) was added so that the entire test piece was immersed in the electrolytic solution. In this state, the glass bottle was covered and sealed. The sealed glass bottle was placed in an oven set at 85° C. and left standing for 24 hours. Next, the glass bottle was taken out from the oven, the test piece was taken out from the glass bottle and washed with water, and the water on the surface of the test piece was wiped off with a towel.

Next, the heat-fusible resin layer and the barrier layer of the test piece are peeled off, and the heat-fusible resin layer side and the barrier layer side of the test piece are subjected to a tensile tester (trade name AGS-XPlus manufactured by Shimadzu Corporation). The test piece was used to pull at a distance between marked lines of 50 mm at a speed of 50 mm/min in the direction of 180°, and the peel strength (N/15 mm) of the test piece was measured. The peel strength of the test piece was measured within 10 minutes after the water on the surface of the test piece was wiped off with a towel. The strength when the distance between the marked lines reached 57 mm was defined as the peel strength of the test piece.

On the other hand, the initial adhesion was evaluated as follows. First, the exterior materials for electric storage devices obtained in Examples 1 and 2 and Comparative Examples 1 to 4 were cut into 15 mm (TD) and 100 mm (MD) sizes to obtain test pieces. Next, the heat-fusible resin layer and the barrier layer of the test piece were peeled off, and the heat-fusible resin layer and the barrier layer were marked by using a tensile tester (trade name AGS-XPlus manufactured by Shimadzu Corporation). The peel strength (N/15 mm) of the test piece was measured by pulling in the direction of 180° at a distance of 50 mm and a speed of 50 mm/min, and the initial adhesion was obtained. The results are shown in Table 1. When the heat-fusible resin layer and the barrier layer are peeled off, the adhesive layer located between these layers is in a state of being laminated on either or both of the heat-fusible resin layer and the barrier layer. Becomes

<Tensile breaking strength of base material layer>
Regarding the biaxially stretched polyethylene terephthalate film used as the base material layer in Examples 1 and 2, and the biaxially stretched nylon film used as the base material layer in Comparative Examples 1 and 2, the machine direction (MD) and the transverse direction ( The tensile breaking strength in TD) is measured using a tensile tester (manufactured by Shimadzu Corporation, AG-Xplus (trade name)). The measurement conditions were a rectangular shape with a sample width of 15 mm, a distance between marked lines of 50 mm, a pulling speed of 50 mm/min, and a test environment of 23°C. The results are shown in Table 1.

In Table 1, PET is a polyethylene terephthalate film, DL is an adhesive layer or an adhesive layer formed by a dry lamination method, ALM is an aluminum alloy foil, PPa is maleic anhydride modified polypropylene, PP is polypropylene, and CPP is an unstretched laminate. Polypropylene film, Ny means nylon film, AD means adhesive layer of PET and Ny. Moreover, the numerical value attached to each layer means the thickness (μm), and for example, the notation “PET25” means “a polyethylene terephthalate film having a thickness of 25 μm”.

As is clear from the results shown in Table 1, the base material layer is composed of a single-layer polyester film, and at least one surface of the barrier layer is provided with a corrosion-resistant film. When analyzed using time-of-flight secondary ion mass spectrometry, the ratio P _PO3 /P _{CePO4 of} the peak intensity P _PO3 derived from PO ₃ ⁻ to the peak intensity P _CePO4 derived from CePO ₄ ⁻ is 80. The outer packaging materials for electricity storage devices of Examples 1 and 2 in the range of 120 to 120 have a corrosion resistant coating on the surface of the barrier layer, but are heat-sealed to the barrier layer after immersion in the electrolytic solution. It can be seen that the adhesiveness with the conductive resin layer is excellent.

As described above, the present disclosure provides the inventions of the aspects described below.
Item 1. At least a base material layer, a barrier layer, and a heat-fusible resin layer is composed of a laminate provided in this order,
The base layer is composed of a single-layer polyester film,
At least one surface of the barrier layer is provided with a corrosion resistant film,
When the corrosion-resistant coating is analyzed by time-of-flight secondary ion mass spectrometry, the ratio of the peak intensity P _PO3 derived from PO ₃ ⁻ to the peak intensity P _CePO4 derived from CePO ₄ ⁻ P _PO3 / An exterior material for an electricity storage device, in which P _CePO4 is in the range of 80 or more and 120 or less.
Item 2. Item 2. The exterior material for an electricity storage device according to Item 1, wherein the corrosion resistant coating is provided on at least the surface of the barrier layer on the side of the heat-fusible resin layer.
Item 3. Item 3. The exterior material for an electricity storage device according to Item 2, wherein the corrosion-resistant coating and the heat-fusible resin layer are laminated with an adhesive layer in between.
Item 4. Item 4. The exterior material for an electricity storage device according to Item 3, wherein the resin forming the adhesive layer has a polyolefin skeleton.
Item 5. Item 5. The exterior material for an electricity storage device according to Item 3 or 4, wherein the adhesive layer contains an acid-modified polyolefin.
Item 6. Item 6. The packaging material for an electricity storage device according to any one of Items 3 to 5, wherein a peak derived from maleic anhydride is detected when the adhesive layer is analyzed by infrared spectroscopy.
Item 7. The acid-modified polyolefin of the adhesive layer is maleic anhydride-modified polypropylene,
Item 7. The exterior material for an electricity storage device according to Item 6, wherein the heat-fusible resin layer contains polypropylene.
Item 8. Any of Items 3 to 7, wherein the adhesive layer 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 a compound having an epoxy group. An exterior material for an electricity storage device according to Crab.
Item 9. Item 3. The adhesive layer is 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. The exterior material for an electricity storage device according to any one of 1 to 8.
Item 10. Item 10. The exterior material for an electricity storage device according to any one of Items 3 to 9, wherein the adhesive layer contains at least one selected from the group consisting of urethane resin, ester resin, and epoxy resin.
Item 11. Item 11. The exterior material for an electricity storage device according to any one of Items 1 to 10, wherein the barrier layer is made of an aluminum alloy foil.
Item 12. Item 12. The exterior material for an electricity storage device according to any one of Items 1 to 11, wherein the resin forming the heat-fusible resin layer contains a polyolefin skeleton.
Item 13. Item 13. The exterior material for an electricity storage device according to any one of Items 1 to 12, which is a packaging material used for an electricity storage device of a mobile device.
Item 14. At least, a base layer, a barrier layer, and a heat-fusible resin layer are laminated in this order to obtain a laminate,
The base layer is composed of a single-layer polyester film,
At least one surface of the barrier layer is provided with a corrosion resistant film,
When the corrosion-resistant coating is analyzed by time-of-flight secondary ion mass spectrometry, the ratio of the peak intensity P _PO3 derived from PO ₃ ⁻ to the peak intensity P _CePO4 derived from CePO ₄ ⁻ P _PO3 / A method for producing an exterior material for an electricity storage device, wherein P _CePO4 is in the range of 80 or more and 120 or less.
Item 15. An electricity storage device, wherein an electricity storage device element including at least a positive electrode, a negative electrode, and an electrolyte is contained in a package formed of the exterior material for an electricity storage device according to any one of Items 1 to 13.

DESCRIPTION OF SYMBOLS 1... Base material layer 2... Adhesive layer 3... Barrier layers 3a and 3b... Corrosion-resistant film 4... Heat-fusible resin layer 5... Adhesive layer 6... Surface coating layer 10... Storage material exterior material

Claims (15)

At least a base material layer, a barrier layer, and a heat-fusible resin layer is composed of a laminate provided in this order,
The base layer is composed of a single-layer polyester film,
At least one surface of the barrier layer is provided with a corrosion resistant film,
When the above corrosion-resistant film is analyzed using time-of-flight secondary ion mass spectrometry, the ratio of the peak intensity P _PO3 derived from PO ₃ ⁻ to the peak intensity P _CePO4 derived from CePO ₄ ⁻ P _PO3 / An exterior material for an electricity storage device, in which P _CePO4 is in the range of 80 or more and 120 or less. The exterior material for an electricity storage device according to claim 1, wherein the corrosion resistant coating is provided on at least the surface of the barrier layer on the side of the heat-fusible resin layer. The exterior material for an electricity storage device according to claim 2, wherein the corrosion-resistant coating and the heat-fusible resin layer are laminated with an adhesive layer in between. The exterior material for an electricity storage device according to claim 3, wherein the resin forming the adhesive layer has a polyolefin skeleton. The exterior material for an electricity storage device according to claim 3, wherein the adhesive layer contains an acid-modified polyolefin. The exterior material for an electricity storage device according to claim 3, wherein a peak derived from maleic anhydride is detected when the adhesive layer is analyzed by infrared spectroscopy. The acid-modified polyolefin of the adhesive layer is maleic anhydride-modified polypropylene,
The exterior material for an electricity storage device according to claim 6, wherein the heat-fusible resin layer contains polypropylene. The adhesive layer 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 a compound having an epoxy group. The exterior material for an electricity storage device according to any one of the above. The adhesive layer is 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. The exterior material for an electricity storage device according to any one of 3 to 8. The exterior material for an electricity storage device according to claim 3, wherein the adhesive layer contains at least one selected from the group consisting of urethane resin, ester resin, and epoxy resin. The exterior material for an electricity storage device according to claim 1, wherein the barrier layer is made of an aluminum alloy foil. The outer casing material for an electricity storage device according to claim 1, wherein the resin forming the heat-fusible resin layer contains a polyolefin skeleton. The packaging material for an electricity storage device according to claim 1, which is a packaging material used for an electricity storage device of a mobile device. At least, a base layer, a barrier layer, and a heat-fusible resin layer are laminated in this order to obtain a laminate,
The base layer is composed of a single-layer polyester film,
At least one surface of the barrier layer is provided with a corrosion resistant film,
When the above corrosion-resistant film is analyzed using time-of-flight secondary ion mass spectrometry, the ratio of the peak intensity P _PO3 derived from PO ₃ ⁻ to the peak intensity P _CePO4 derived from CePO ₄ ⁻ P _PO3 / A method for producing an exterior material for an electricity storage device, wherein P _CePO4 is in the range of 80 or more and 120 or less. An electricity storage device, wherein an electricity storage device element including at least a positive electrode, a negative electrode, and an electrolyte is housed in a package formed of the exterior material for an electricity storage device according to claim 1.