WO2022210750A1

WO2022210750A1 - Exterior material for power storage device, power storage device, and method for manufacturing same

Info

Publication number: WO2022210750A1
Application number: PCT/JP2022/015613
Authority: WO
Inventors: 真天野; ゆう木村; 雅博立沢; 孝典山下
Original assignee: 大日本印刷株式会社
Priority date: 2021-04-01
Filing date: 2022-03-29
Publication date: 2022-10-06
Also published as: CN117083751A; JPWO2022210750A1

Abstract

This exterior material for a power storage device includes a film laminate in which at least a substrate layer, an adhesive layer, a barrier layer, and a heat-sealing resin layer are provided in this order. The exterior material for the power storage device has a recessed portion that is formed so as to protrude from the heat-sealing resin layer side to the substrate layer side and accommodate a power storage device element on the heat-sealing resin layer side. In a cross section of the adhesive layer in the thickness direction, a porosity of 25% or less is observed with a 150-fold magnification of an objective lens.

Description

Exterior material for power storage device, power storage device, and manufacturing method thereof

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

Various types of power storage devices have been developed in the past, but in all power storage devices, the exterior material is an indispensable member for sealing the power storage device elements such as electrodes and electrolytes. Conventionally, metal exterior materials have been frequently used as exterior materials for power storage devices.

On the other hand, in recent years, with the increasing performance of electric vehicles, hybrid electric vehicles, personal computers, cameras, mobile phones, etc., power storage devices are required to have various shapes, as well as to be thinner and lighter. However, conventionally widely used metallic exterior materials for electric storage devices have the drawback that it is difficult to follow the diversification of shapes and that there is a limit to weight reduction.

Therefore, in recent years, a film-like exterior material that can be easily processed into various shapes and that can realize thinness and weight reduction has been developed. Laminates have been proposed (see Patent Document 1, for example).

In such a power storage device exterior material, generally, recesses are formed by cold molding using a mold, and power storage device elements such as electrodes and electrolytes are arranged in the spaces formed by the recesses. By heat-sealing the heat-fusible resin layer, an electricity storage device in which the electricity storage device element is housed inside the exterior material for an electricity storage device can be obtained.

JP 2008-287971 A

From the perspective of extending the life of power storage devices and using them in harsh environments, it is necessary to improve the resistance to heat and humidity of power storage devices. In order to improve the heat and humidity resistance of an electricity storage device, it is necessary to improve the heat and humidity resistance of the exterior material for the electricity storage device.

The inventors of the present disclosure conducted various analyzes and evaluations focusing on exterior materials for power storage devices in which concave portions were formed by molding. Then, when a cross section in the thickness direction of the adhesive layer positioned between the base material layer and the barrier layer was observed with a microscope, a new finding was obtained that voids were present in the cross section. Such knowledge has not been known in the past, and the inventors of the present disclosure conducted further studies. As a result, by setting the porosity of the cross section of the adhesive layer to a predetermined value or less, even when the molded exterior material for an electricity storage device is placed in a hot and humid environment for a long period of time, the exterior material for an electricity storage device does not have a concave portion. It was found that delamination between the substrate layer and the barrier layer (that is, the portion where the adhesive layer is present) is suppressed at the position where it is bent for forming.

Under such circumstances, the present disclosure is a power storage device in which a film-like laminate is formed that includes at least a base layer, an adhesive layer, a barrier layer, and a heat-fusible resin layer in this order. A main object of the present invention is to provide an exterior material for an electricity storage device, which is an exterior material and has excellent moisture and heat resistance.

The inventors of the present disclosure have diligently studied to solve the above problems. As a result, an exterior material for an electricity storage device in which a film-like laminate including at least a substrate layer, an adhesive layer, a barrier layer, and a heat-fusible resin layer in this order is formed, In an exterior material for an electricity storage device that is molded so as to protrude from the adhesive resin layer side to the base layer side and has a concave portion for housing the electricity storage device element on the heat-fusible resin layer side, the thickness direction of the adhesive layer By adjusting the porosity observed at a magnification of 150 times of the objective lens to 25% or less for the cross section of the It was discovered that it exhibited moist heat resistance.

Conventionally, no special means has been adopted to reduce the porosity of the adhesive layer. adopted various means.

The present disclosure has been completed through further studies based on these findings. That is, the present disclosure provides inventions in the following aspects.
An exterior material for an electricity storage device, in which a film-like laminate is formed comprising at least a substrate layer, an adhesive layer, a barrier layer, and a heat-fusible resin layer in this order,
The power storage device exterior material is molded so as to protrude from the heat-fusible resin layer side to the base layer side, and has a recessed portion in which the power storage device element is accommodated on the heat-fusible resin layer side. and
An exterior material for an electric storage device, wherein the adhesive layer has a porosity of 25% or less in a cross-section in the thickness direction, as observed at a magnification of 150 times with an objective lens.

According to the present disclosure, an exterior material for an electricity storage device is formed by forming a film-like laminate that includes at least a substrate layer, an adhesive layer, a barrier layer, and a heat-fusible resin layer in this order. As a result, it is possible to provide an exterior material for an electricity storage device that has excellent moisture and heat resistance. Further, according to the present disclosure, it is also possible to provide a method for manufacturing an exterior material for an electricity storage device, an electricity storage device, and a method for manufacturing the same.

FIG. 2 is a schematic cross-sectional view showing an example of the laminated structure of the exterior material for an electricity storage device of the present disclosure; FIG. 2 is a schematic cross-sectional view showing an example of the laminated structure of the exterior material for an electricity storage device of the present disclosure; FIG. 2 is a schematic cross-sectional view showing an example of the laminated structure of the exterior material for an electricity storage device of the present disclosure; 1 is a schematic diagram of a plain view of an exterior material for an electricity storage device of the present disclosure; FIG. FIG. 5 is a schematic cross-sectional view obtained by cutting the power storage device exterior material in a direction parallel to the MD (Machine Direction) direction (x-axis direction) and the thickness direction of FIG. 4 (the lamination structure is omitted). FIG. 6 is a schematic diagram showing a state in which the exterior material for an electricity storage device shown in FIG. 5 is folded back and the heat-fusible resin layers are heat-sealed to each other at the position of the edge for sealing. FIG. 4 is a schematic diagram for explaining how a female mold and a male mold are used to mold an exterior material for an electricity storage device to form a recess. FIG. 4 is a schematic diagram for explaining how a female mold and a male mold are used to mold an exterior material for an electricity storage device to form a recess. It is a schematic diagram for demonstrating the measuring method of the porosity of an adhesive bond layer. It is a schematic diagram for demonstrating the measuring method of the porosity of an adhesive bond layer.

The exterior material for an electricity storage device of the present disclosure is for an electricity storage device, in which a film-like laminate including at least a base layer, an adhesive layer, a barrier layer, and a heat-fusible resin layer in this order is formed. The exterior material for an electricity storage device is formed so as to protrude from the heat-fusible resin layer side to the base layer side, and the heat-fusible resin layer side has a concave portion in which the electricity storage device element is accommodated. and a porosity of 25% or less observed at a magnification of 150 with an objective lens in a cross section of the adhesive layer in the thickness direction. By having the configuration, the power storage device exterior material of the present disclosure suppresses peeling at the position of the adhesive layer of the power storage device exterior material in a moist and heat environment, and exhibits excellent heat and humidity resistance.

The exterior material for an electricity storage device of the present disclosure will be described in detail below. In this specification, the numerical range indicated by "-" means "more than" and "less than". For example, the notation of 2 to 15 mm means 2 mm or more and 15 mm or less.

The present disclosure is an exterior material for an electricity storage device, in which a film-like laminate including at least a substrate layer, an adhesive layer, a barrier layer, and a heat-fusible resin layer in this order is formed. Hereinafter, the shape and laminated structure of the power storage device exterior material of the present disclosure will be described first, and then the details of each layer constituting the laminate constituting the power storage device exterior material of the present disclosure, and the power storage device exterior material. The manufacturing method of and the like will be sequentially described.

In addition, in the exterior material for an electricity storage device, the barrier layer 3 described later can usually be distinguished between MD (Machine Direction) and TD (Transverse Direction) in the manufacturing process. For example, when the barrier layer 3 is made of a metal foil such as an aluminum alloy foil or a stainless steel foil, there are lines called rolling marks on the surface of the metal foil in the rolling direction (RD) of the metal foil. shaped streaks are formed. Since the rolling marks extend along the rolling direction, the rolling direction of the metal foil can be grasped by observing the surface of the metal foil. In addition, in the manufacturing process of the laminate, the MD of the laminate usually matches the RD of the metal foil, so the surface of the metal foil of the laminate is observed to identify the rolling direction (RD) of the metal foil. Thus, the MD of the laminate can be specified. Moreover, since the TD of the laminate is perpendicular to the MD of the laminate, the TD of the laminate can also be specified.

In addition, when the MD of the exterior material for an electricity storage device cannot be specified due to the rolling marks of metal foil such as aluminum alloy foil or stainless steel foil, it can be specified by the following method. As a method for confirming the MD of the exterior material for an electricity storage device, there is a method for confirming the sea-island structure by observing the cross section of the heat-fusible resin layer of the exterior material for the electricity storage device with an electron microscope. In this method, the MD can be determined as the direction parallel to the cross section in which the average diameter of the island shape in the direction perpendicular to the thickness direction of the heat-fusible resin layer is maximum. Specifically, the cross section in the length direction of the heat-fusible resin layer is changed by 10 degrees from a direction parallel to the cross section in the length direction, and the direction is perpendicular to the cross section in the length direction. (10 cross sections in total) are observed with electron micrographs to confirm the sea-island structure. Next, in each cross section, the shape of each individual island is observed. Regarding the shape of each island, the linear distance connecting the leftmost end in the direction perpendicular to the thickness direction of the heat-sealable resin layer and the rightmost end in the perpendicular direction is defined as the diameter y. In each cross section, the average of the top 20 diameters y of the island shape is calculated in descending order of diameter y. The direction parallel to the cross section in which the average diameter y of the island shape is the largest is determined as the MD.

1. Shape and Laminate Structure of Electricity Storage Device Exterior Material The electricity storage device exterior material 10 of the present disclosure, for example, as shown in the schematic diagrams of FIGS. The recess 100 is formed so as to protrude outward (so as to accommodate the electricity storage device element), and has a concave portion 100 in which the electricity storage device element is accommodated on the heat-fusible resin layer 4 side. The recess 100 is formed by molding. That is, the power storage device exterior material 10 of the present disclosure is a film-like laminate that includes at least a base layer 1, an adhesive layer 2, a barrier layer 3, and a heat-fusible resin layer 4 in this order, It is formed so as to protrude from the heat-fusible resin layer 4 side toward the substrate layer 1 side, and a concave portion 100 is formed on the heat-fusible resin layer 4 side to accommodate the electricity storage device element.

The power storage device exterior material 10 shown in FIGS. 4 and 5 has a substantially rectangular shape in plan view. Moreover, the concave portion 100 of the power storage device exterior material 10 shown in FIGS. 4 and 5 has a substantially rectangular shape in plan view. The shape of the power storage device exterior material 10 and the shape of the recess are not particularly limited, and may be determined in consideration of the shape of the power storage device. There are various shapes of recesses formed by molding the exterior material for an electric storage device. For example, planar view substantially rectangular shape, planar view substantially L shape, planar view substantially U shape, etc. are mentioned. These shapes are examples of common recess shapes. In this specification, for example, "substantially rectangular shape" means a rectangular shape in which the corners of the four corners of the rectangle are right angles, and a rectangular shape in which the four corners of the rectangle are rounded (R). It means to include. The same applies to substantially L-shaped, substantially U-shaped, and the like.

For example, as shown in FIGS. 4 and 5, a female mold (having a substantially rectangular opening in a plan view) disposed on the base layer 1 side of a laminate constituting an exterior material for an electric storage device, and heat-sealing Using a male mold (having a convex shape corresponding to the female mold) arranged on the side of the adhesive resin layer 4, the laminate is formed so as to protrude from the side of the heat-fusible resin layer 4 to the side of the base material layer 1. By molding, a substantially rectangular recess in plan view is formed on the side of the heat-fusible resin layer 4 to accommodate the electricity storage device element (see also FIGS. 7 and 8). A power storage device element is accommodated in the space formed by the recess. The shape of the space is various, and includes, for example, a substantially rectangular parallelepiped shape, a substantially cylindrical shape, a substantially elliptical cylindrical shape, and a substantially multi-stage shape. In the present specification, the term “substantially rectangular parallelepiped shape” means a rectangular parallelepiped shape in which each corner portion of the rectangular parallelepiped is a right angle, and for example, a rectangular parallelepiped shape in which each corner portion is rounded (R). is. The same applies to substantially circular cylinders, substantially elliptical cylinders, substantially multi-stage shapes, and the like.

Although the shape of the recessed portion (space) formed by molding the exterior material for an electric storage device varies, the laminate is stretched during molding, which causes a local burden (that is, a large local stress is applied). Delamination in a hot and humid environment is particularly likely to occur at some points. Therefore, it is effective to measure the porosity of the adhesive layer at the location where the load is applied. When the shape of the recess (space) formed by molding the exterior material for an electric storage device is, for example, a shape having a corner portion and a ridge line portion on the sealing edge side, a curved line forming the corner portion and a straight line forming the ridge line are formed. The boundary portion is a portion where a burden is applied during molding. That is, for example, as shown in FIGS. 4 and 5, when a substantially rectangular concave portion 100 in plan view is formed on the side of the sealing edge 10C (FIG. 5), the concave portion 100 in FIG. Although it has a part, the boundary part between the curve forming the corner part and the straight line forming the ridge part (in FIG. 4, the place where the solid line indicating the recess 100 and the broken lines (1) to (8) intersect) is a burden during molding This is the point where the Therefore, it is effective to measure the porosity of the section in the thickness direction of the portion. At this time, since peeling in a moist and hot environment is particularly likely to occur, among the cross sections, the sealing edge of the bent portion 10A on the bottom surface 100A side of the recess 100 and the bent portion 10B on the sealing edge 10C side of the recess 100 It is effective to use the cross section of the bent portion 10B on the 10C side (see region P in FIG. 5) as an object for porosity measurement. For reference, a schematic diagram showing a state in which the electrical storage device exterior material 10 shown in FIG. It is shown in FIG. 4 to 6, the power storage device exterior material 10 is folded back and the heat-sealable resin layers 4 are heat-sealed. When the heat-fusible resin layers 4 of the exterior material 10 are opposed to each other and heat-sealed, or when the heat-fusible resin layers 4 of two molded exterior materials 10 for an electricity storage device are opposed to each other and heat-sealed. There are also cases where The same applies to these cases. In addition, in the case of folding back and heat-sealing, in FIG. 6, it is folded so that there is an edge at 10C on the left side of the figure, but it may be folded so that there is no edge.

7 and 8 schematically show how the power storage device exterior material 10 is molded using a female die 21, a male die 22, and a pressing plate 23 to form a recess. When the power storage device exterior material 10 is molded to form recesses using the female mold 21, the male mold 22, and the pressing plate 23 as shown in FIGS. A bent portion 10A (see FIGS. 5 to 8) is a bent portion formed by the male mold 22, and a bent portion 10B described later is a bent portion formed by the female mold 21. FIG.

The depth of the concave portion 100 of the power storage device exterior material 10 of the present disclosure is appropriately adjusted according to the size of the power storage device, and is, for example, about 4 to 10 mm.

In the exterior material for an electricity storage device after molding of the present disclosure, the period until peeling occurs, which is evaluated by the following <Evaluation of moist heat resistance>, is preferably 5 days or more, more preferably 10 days or more, and more preferably is 20 days or more, more preferably 30 days or more.

<Evaluation of moist heat resistance>
First, an unmolded exterior material for an electricity storage device is cut into strips of 150 mm (MD: Machine Direction) x 90 mm (TD: Transverse Direction). The MD of the power storage device exterior material corresponds to the rolling direction (RD) of the aluminum alloy foil, and the TD of the power storage device exterior material corresponds to the TD of the aluminum alloy foil. Next, a strip is placed between a molding die (female mold) having a diameter of 55 mm (MD) x 32 mm (TD) and a corresponding molding die (male mold) (the female mold side is the base layer side), and cold forming is performed with a pressing pressure of 0.9 MPa and a forming depth of 5.5 mm to obtain a formed exterior material for an electricity storage device (see FIGS. 4 and 5). Next, 16 pieces of each of the obtained exterior materials for electric storage devices after molding are prepared and used as samples. Next, 16 samples are placed in a constant temperature bath at a temperature of 80 ° C. and a relative humidity of 90%, and the occurrence of peeling between the aluminum alloy foil and the biaxially oriented nylon film of the base layer is checked every day. visually observe. When the biaxially oriented nylon film is observed to be peeled off from the aluminum alloy foil by 1 mm or more, it is determined that peeling has occurred, and the number of days until peeling occurs is counted for all 16 samples. It can be said that it is a very severe evaluation to evaluate the heat and humidity resistance of the molded exterior material for an electricity storage device under conditions of a temperature of 80° C. and a relative humidity of 90%.

2. Laminated Structure of Exterior Material for Electricity Storage Device The exterior material 10 for an electricity storage device of the present disclosure includes, for example, as shown in FIGS. It consists of a laminate comprising layers 4 in that order. In the power storage device exterior material 10, the base material layer 1 is the outermost layer, and the heat-fusible resin layer 4 is the innermost layer. When an electricity storage device is assembled using the electricity storage device exterior material 10 and an electricity storage device element, the heat-sealable resin layers 4 of the electricity storage device exterior material 10 face each other, and the peripheral edges are heat-sealed. The electricity storage device element is accommodated in the space formed by . In the laminate constituting the exterior material 10 for an electricity storage device of the present disclosure, the barrier layer 3 is the reference, the heat-fusible resin layer 4 side is inner than the barrier layer 3, and the base layer 1 side is more than the barrier layer 3. outside.

For example, as shown in FIGS. 2 and 3, the electrical storage device exterior material 10 is provided between the barrier layer 3 and the heat-fusible resin layer 4 for the purpose of improving the adhesion between these layers. It may have an adhesive layer 5 depending on the requirements. Further, as shown in FIG. 3, a surface coating layer 6 or the like may be provided on the outside of the base material layer 1 (the side opposite to the heat-fusible resin layer 4 side), if necessary. In the electrical storage device exterior material 10, the barrier layer 3 is preferably one layer.

The thickness of the laminate that constitutes the power storage device exterior material 10 is not particularly limited, but from the viewpoint of cost reduction, energy density improvement, etc., it is, for example, 190 μm or less, preferably about 180 μm or less, about 155 μm or less, or about 120 μm or less. is mentioned. The thickness of the laminate constituting the power storage device exterior material 10 is preferably about 35 μm or more, about 45 μm or more, about 60 μm or more can be mentioned. Further, the preferred range of the laminate constituting the power storage device exterior material 10 is, for example, about 35 to 190 μm, about 35 to 180 μm, about 35 to 155 μm, about 35 to 120 μm, about 45 to 190 μm, and about 45 to 180 μm. , about 45 to 155 μm, about 45 to 120 μm, about 60 to 190 μm, about 60 to 180 μm, about 60 to 155 μm, and about 60 to 120 μm, and particularly preferably about 60 to 155 μm.

In the power storage device exterior material 10, the base material layer 1, the adhesive layer 2, the barrier layer 3, and the adhesive layer 5 provided as necessary with respect to the thickness (total thickness) of the laminate constituting the power storage device exterior material 10 , the heat-fusible resin layer 4, and the surface coating layer 6, which is provided as necessary, are preferably 90% or more, more preferably 95% or more, and still more preferably 98% or more. is. As a specific example, when the electrical storage device exterior material 10 of the present disclosure includes the base material layer 1, the adhesive layer 2, the barrier layer 3, the adhesive layer 5, and the heat-fusible resin layer 4, the electrical storage device exterior The ratio of the total thickness of each layer to the thickness (total thickness) of the laminate constituting the material 10 is preferably 90% or more, more preferably 95% or more, and still more preferably 98% or more. Further, when the power storage device exterior material 10 of the present disclosure is a laminate including the base material layer 1, the adhesive layer 2, the barrier layer 3, and the heat-fusible resin layer 4, the power storage device exterior material The ratio of the total thickness of each of these layers to the thickness (total thickness) of the laminate constituting 10 is, for example, 80% or more, preferably 90% or more, more preferably 95% or more, and further preferably 98% or more. can be done.

3. Each layer of the exterior material for the electricity storage device [base layer 1]
In the present disclosure, the base material layer 1 is a layer provided for the purpose of exhibiting a function as a base material of an exterior material for an electric storage device. The base material layer 1 is located on the outer layer side of the exterior material for electrical storage devices.

The material forming the base material layer 1 is not particularly limited as long as it functions as a base material, that is, at least has insulating properties. The base material layer 1 can be formed using, for example, a resin, and the resin may contain additives described later.

When the substrate layer 1 is made of resin, the substrate layer 1 may be, for example, a resin film made of resin, or may be formed by applying resin. The resin film may be an unstretched film or a stretched film. Examples of stretched films include uniaxially stretched films and biaxially stretched films, with biaxially stretched films being preferred. Examples of stretching methods for forming a biaxially stretched film include successive biaxial stretching, inflation, and simultaneous biaxial stretching. Methods for applying the resin include a roll coating method, a gravure coating method, an extrusion coating method, and the like.

Examples of resins forming the base material layer 1 include resins such as polyester, polyamide, polyolefin, epoxy resin, acrylic resin, fluororesin, polyurethane, silicon resin, phenolic resin, and modified products of these resins. Further, the resin forming the base material layer 1 may be a copolymer of these resins or a modified product of the copolymer. Furthermore, it may be a mixture of these resins.

Among these, polyesters and polyamides are preferred as resins forming the base material layer 1 .

Specific examples of polyester include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolymerized polyester. Examples of copolyester include copolyester having ethylene terephthalate as a main repeating unit. Specifically, copolymer polyester polymerized with ethylene isophthalate with ethylene terephthalate as the main repeating unit (hereinafter abbreviated after polyethylene (terephthalate / 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 singly or in combination of two or more.

Further, as the polyamide, specifically, aliphatic polyamide such as nylon 6, nylon 66, nylon 610, nylon 12, nylon 46, copolymer of nylon 6 and nylon 66; terephthalic acid and / or isophthalic acid Hexamethylenediamine-isophthalic acid-terephthalic acid copolymer polyamide such as nylon 6I, nylon 6T, nylon 6IT, nylon 6I6T (I represents isophthalic acid, T represents terephthalic acid) containing structural units derived from, polyamide MXD6 (polymetallic Polyamides containing aromatics such as silylene adipamide); alicyclic polyamides such as polyamide PACM6 (polybis(4-aminocyclohexyl)methane adipamide); Copolymerized polyamides, polyesteramide copolymers and polyetheresteramide copolymers which are copolymers of copolymerized polyamides with polyesters or polyalkylene ether glycols; and polyamides such as these copolymers. These polyamides may be used singly or in combination of two or more.

The substrate layer 1 preferably includes at least one of a polyester film, a polyamide film, and a polyolefin film, preferably includes at least one of a stretched polyester film, a stretched polyamide film, and a stretched polyolefin film, More preferably, at least one of an oriented polyethylene terephthalate film, an oriented polybutylene terephthalate film, an oriented nylon film, and an oriented polypropylene film is included, and the biaxially oriented polyethylene terephthalate film, biaxially oriented polybutylene terephthalate film, and biaxially oriented nylon film , biaxially oriented polypropylene film.

The base material layer 1 may be a single layer, or may be composed of two or more layers. When the substrate layer 1 is composed of two or more layers, the substrate layer 1 may be a laminate obtained by laminating resin films with an adhesive or the like, or may be formed by co-extrusion of resin to form two or more layers. It may also be a laminate of resin films. A laminate of two or more resin films formed by coextrusion of resin may be used as the base material layer 1 without being stretched, or may be used as the base material layer 1 by being uniaxially or biaxially stretched.

Specific examples of the laminate of two or more resin films in the substrate layer 1 include a laminate of a polyester film and a nylon film, a laminate of nylon films of two or more layers, and a laminate of polyester films of two or more layers. etc., preferably a laminate of a stretched nylon film and a stretched polyester film, a laminate of two or more layers of stretched nylon films, and a laminate of two or more layers of stretched polyester films. For example, when the substrate layer 1 is a laminate of two layers of resin films, a laminate of polyester resin films and polyester resin films, a laminate of polyamide resin films and polyamide resin films, or a laminate of polyester resin films and polyamide resin films. A laminate is preferred, and a laminate of polyethylene terephthalate film and polyethylene terephthalate film, a laminate of nylon film and nylon film, or a laminate of polyethylene terephthalate film and nylon film is more preferred. In addition, the polyester resin is resistant to discoloration when, for example, an electrolytic solution adheres to the surface. It is preferably located in the outermost layer.

When the substrate layer 1 is a laminate of two or more layers of resin films, the two or more layers of resin films may be laminated via an adhesive. Preferred adhesives are the same as those exemplified for the adhesive layer 2 described later. The method for laminating two or more layers of resin films is not particularly limited, and known methods can be employed. Examples thereof include dry lamination, sandwich lamination, extrusion lamination, thermal lamination, and the like. A lamination method is mentioned. When laminating by dry lamination, it is preferable to use an adhesive containing polyurethane as the adhesive. At this time, the thickness of the adhesive is, for example, about 2 to 5 μm. Alternatively, an anchor coat layer may be formed on the resin film and laminated. Examples of the anchor coat layer include the same adhesives as those exemplified for the adhesive layer 2 described later. At this time, the thickness of the anchor coat layer is, for example, about 0.01 to 1.0 μm.

At least one of the surface and the inside of the substrate layer 1 may contain additives such as lubricants, flame retardants, antiblocking agents, antioxidants, light stabilizers, tackifiers, and antistatic agents. good. Only one type of additive may be used, or two or more types may be mixed and used.

In the present disclosure, it is preferable that a lubricant exists on the surface of the base material layer 1 from the viewpoint of improving the moldability of the exterior material for an electricity storage device. The lubricant is not particularly limited, but preferably includes an amide-based lubricant. Specific examples of amide lubricants include saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, methylolamides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, fatty acid ester amides, and aromatic bisamides. Specific examples of saturated fatty acid amides include lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, and hydroxystearic acid amide. Specific examples of unsaturated fatty acid amides include oleic acid amide and erucic acid amide. Specific examples of substituted amides include N-oleyl palmitic acid amide, N-stearyl stearic acid amide, N-stearyl oleic acid amide, N-oleyl stearic acid amide, N-stearyl erucic acid amide and the like. Further, specific examples of methylolamide include methylol stearamide. Specific examples of saturated fatty acid bisamides include methylenebisstearic acid amide, ethylenebiscapric acid amide, ethylenebislauric acid amide, ethylenebisstearic acid amide, ethylenebishydroxystearic acid amide, ethylenebisbehenic acid amide, hexamethylenebisstearin. acid amide, hexamethylenebisbehenamide, hexamethylenehydroxystearic acid amide, N,N'-distearyladipic acid amide, N,N'-distearylsebacic acid amide and the like. Specific examples of unsaturated fatty acid bisamides include ethylenebisoleic acid amide, ethylenebiserucic acid amide, hexamethylenebisoleic acid amide, N,N'-dioleyladipic acid amide, and N,N'-dioleylsebacic acid amide. etc. Specific examples of fatty acid ester amides include stearamide ethyl stearate. Further, specific examples of the aromatic bisamide include m-xylylenebisstearic acid amide, m-xylylenebishydroxystearic acid amide, N,N'-distearyl isophthalic acid amide and the like. Lubricants may be used singly or in combination of two or more.

When a lubricant exists on the surface of the base material layer 1, its amount is not particularly limited, but is preferably about 3 mg/m ² or more, more preferably about 4 to 15 mg/m ² , and still more preferably 5 to 14 mg. / m ² degree.

The lubricant present on the surface of the substrate layer 1 may be obtained by exuding the lubricant contained in the resin constituting the substrate layer 1, or by coating the surface of the substrate layer 1 with the lubricant. may

The thickness of the base material layer 1 is not particularly limited as long as it functions as a base material, but it is, for example, about 3 to 50 μm, preferably about 10 to 35 μm. When the substrate layer 1 is a laminate of two or more resin films, the thickness of each resin film constituting each layer is preferably about 2 to 25 μm.

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

In the present disclosure, the porosity of the cross section of the adhesive layer 2 in the thickness direction observed at a magnification of 150 times of the objective lens is 25% or less. In the power storage device exterior material 10 of the present disclosure, the porosity of the adhesive layer 2 located between the base material layer 1 and the barrier layer 3 is set to 25% or less. Peeling (delamination) at the position of the adhesive layer 2 of the power storage device exterior material 10 is suppressed, and excellent moist heat resistance can be exhibited.

Although the porosity of the adhesive layer 2 may be 25% or less, it is preferably 21% or less, more preferably 15% or less, and still more preferably 10% or less from the viewpoint of more preferably exhibiting the effects of the present disclosure. % or less, more preferably 8% or less, more preferably 5% or less, still more preferably 3% or less. The porosity is preferably 0.5% or more, most preferably 0%. In the present disclosure, preferred ranges for the porosity include 0 to 25%, 0 to 21%, 0 to 15%, 0 to 10%, 0 to 8%, 0 to 5%, 0 to 3%, 0.3%, 5-25%, 0.5-21%, 0.5-15%, 0.5-10%, 0.5-8%, 0.5-5%, 0.5-3%, etc. . However, from the viewpoint of improving the moldability of the exterior material for an electric storage device, the presence of some voids in the adhesive layer 2 reduces the load that the adhesive layer 2 exerts on the base layer 1 and the barrier layer 3 during molding. can be expected to relax.

The porosity of the adhesive layer 2 is a value obtained by measuring a cross section of the adhesive layer 2 in the thickness direction with a laser microscope at a magnification of 150 times with an objective lens. It is desirable to measure the cross section of (particularly, the bent portion of the exterior material for an electric storage device). For example, as shown in FIGS. 4 and 5, if the shape of the concave portion 100 is substantially rectangular in plan view, when the power storage device exterior material 10 is observed from the base layer 1 side, in plan view Regarding the concave portion 100 (molding portion) formed in a substantially rectangular shape, the boundary portion between the curved line forming the corner portion of the concave portion 100 and the straight line forming the ridge portion (in FIG. 4, the solid line indicating the concave portion 100 and (1) to ( 8) where the dashed lines intersect) are cut in a direction parallel to the thickness direction (and in a direction perpendicular to the side to be cut) with a commercially available microtome (eg, ROM-380 manufactured by Yamato Koki Kogyo Co., Ltd.), and glued. A cross section of the agent layer 2 is obtained. In addition, when the power storage device exterior material is observed from the substrate layer 1 side in the concave portion 100 having a substantially rectangular shape in plan view formed by the mold, the corner portions of the concave portion 100 do not form ideal right angles. It becomes curved. This is because the corner portion is generally rounded when molding the exterior material for an electric storage device. The cross section of the observation target is taken at the boundary portion between the curved line forming the corner portion of the recess 100 and the straight line forming the ridge portion (in FIG. 4, the place where the solid line indicating the recess 100 and the broken lines (1) to (8) intersect). It is preferable to obtain As described above, the shape of the recessed portion (space) formed by molding the exterior material for an electric storage device varies, but in places where the laminate is stretched during molding and locally burdened, peeling in a moist and hot environment is particularly likely to occur. Therefore, it is effective to measure the porosity of the adhesive layer at the location where the load is applied. When the shape of the recess (space) formed by molding the exterior material for an electric storage device is, for example, a shape having a corner portion and a ridge line portion on the sealing edge side, a curved line forming the corner portion and a straight line forming the ridge line are formed. The boundary portion is a portion where a burden is applied during molding. That is, for example, as shown in FIGS. 4 and 5, when a substantially rectangular concave portion 100 in plan view is formed on the side of the sealing edge 10C (FIG. 5), the concave portion 100 in FIG. Although it has a part, the boundary part between the curve forming the corner part and the straight line forming the ridge part (in FIG. 4, the place where the solid line indicating the recess 100 and the broken lines (1) to (8) intersect) is a burden during molding This is the point where the Therefore, it is effective to measure the porosity of the section in the thickness direction of the portion. For the cross sections obtained at the eight locations, the porosity of the cross section of the bent portion 10B on the sealing edge 10C side (see region P in FIG. 5) is measured, and the porosity with the largest measured value is It can be the porosity of the adhesive layer 2 of the device exterior material. For the same reason, even when the concave portion is not substantially rectangular in plan view, the bent portion on the sealing edge 10C side of the bent portion on the bottom surface 100A side and the sealing edge 10C side of the concave portion 100 It is effective to measure the porosity of the cross section of

The porosity is measured by observing the cross section of the adhesive layer 2 with a commercially available laser microscope (eg VK-9710 manufactured by KEYENCE) with an objective lens of 150x magnification. Subsequently, from the cross-sectional observation results obtained, the area of the adhesive layer 2 and the area of the voids are quantified using analysis software (for example, VK Analyzer version 2.5.0.1). Specifically, select the volume and area (V) of the evaluation analysis (A) of the VK Analyzer, select the "polygon" mode for the area of the adhesive layer, and all the adhesive layers represented in the acquired image The area is measured by connecting the points by choosing 5 points between the barrier layer and the adhesive layer and 5 points between the adhesive layer and the substrate layer so that they are included. In addition, the "free line" mode is selected for the gap, and the area is measured by enclosing it with a line so that the entire gap is filled. The ratio of the obtained areas is calculated by the following formula to obtain the cross-sectional porosity (%). When the porosity is measured on the cross section at the eight positions (see the places where the solid line indicating the recess 100 and the broken lines (1) to (8) intersect in FIG. 4), the measured values at a total of eight positions Among them, the value with the largest porosity is adopted.
Porosity (%) of the cross section of the adhesive layer = (cross-sectional area of voids in the adhesive layer/cross-sectional area of the adhesive layer) x 100

As a method for reducing the porosity of the adhesive layer 2 to 25% or less, not only selection of the type of adhesive but also In addition, it is required to design the adhesive layer 2 so as not to generate air bubbles as much as possible. For example, by increasing the lamination pressure when laminating the base material layer 1 and the barrier layer 3 with the adhesive layer 2 interposed therebetween, air trapped in the adhesive layer 2 when the base material layer 1 and the barrier layer 3 are laminated. is crushed to reduce the air remaining in the adhesive layer 2, thereby suppressing the generation of voids. In addition, by increasing the diameter of the nip roll used when laminating the base layer 1 and the barrier layer 3 with the adhesive layer 2 interposed therebetween, the adhesive layer 1 and the barrier layer 3 are laminated together. A method of suppressing the generation of voids by increasing the time and area for crushing the air caught in the adhesive layer 2 and reducing the air remaining in the adhesive layer 2 can be mentioned. Furthermore, when laminating the base material layer 1 and the barrier layer 3 with the adhesive layer 2 interposed therebetween, the base material layer 1 is laminated after the adhesive for forming the adhesive layer 2 is applied to the surface of the barrier layer 3. By doing so, the air caught in the lamination of the base material layer 1 gradually volatilizes from the side of the base material layer 1 after lamination, so that the generation of voids can be suppressed. On the other hand, when the barrier layer 3 is laminated after the adhesive for forming the adhesive layer 2 is applied to the surface of the base material layer 1, the air caught in the lamination of the barrier layer 3 is Since it cannot volatilize from the barrier layer 3 side, voids are likely to be formed in the adhesive layer 2 . At least one of these methods is selected to suppress inclusion of air bubbles in the adhesive layer 2 and reduce the porosity.

The adhesive layer 2 is made of an adhesive that can bond the base material layer 1 and the barrier layer 3 together. The adhesive used to form the adhesive layer 2 is not limited, but may be any of a chemical reaction type, a solvent volatilization type, a hot melt type, a hot pressure type, and the like. Further, it may be a two-liquid curing adhesive (two-liquid adhesive), a one-liquid curing adhesive (one-liquid adhesive), or a resin that does not involve a curing reaction. Further, the adhesive layer 2 may be a single layer or multiple layers.

The adhesive is preferably a resin composition containing a curable resin, and the adhesive layer 2 is preferably formed from a cured product of the resin composition. Specific examples of the curable resin (adhesive component) contained in the adhesive include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, polyester such as copolymer polyester; polyether; Polyurethane; Epoxy resin; Phenol resin; Polyamide such as nylon 6, nylon 66, nylon 12, copolyamide; Polyolefin resin such as polyolefin, cyclic polyolefin, acid-modified polyolefin, acid-modified cyclic polyolefin; meth)acrylic resin; polyimide; polycarbonate; amino resin such as urea resin and melamine resin; rubber such as chloroprene rubber, nitrile rubber and styrene-butadiene rubber; These adhesive components may be used singly or in combination of two or more. Among these curable resins, polyurethane is preferred. That is, the adhesive layer 2 is preferably made of a cured resin composition containing polyurethane. In addition, an appropriate curing agent can be used in combination with these adhesive component resins to increase the adhesive strength. The curing agent is selected from among polyisocyanates, polyfunctional epoxy resins, oxazoline group-containing polymers, polyamine resins, acid anhydrides, etc., depending on the functional groups of the adhesive component.

Examples of polyurethanes include polyurethanes containing a first agent containing a polyol compound and a second agent containing an isocyanate compound. Preferred examples include a two-component curing type polyurethane in which a polyol such as polyester polyol, polyether polyol, or acrylic polyol is used as the first agent and an aromatic or aliphatic polyisocyanate is used as the second agent. Examples of polyurethane include polyurethane containing a polyurethane compound obtained by reacting a polyol compound and an isocyanate compound in advance and an isocyanate compound. Examples of polyurethane include polyurethane containing a polyurethane compound obtained by reacting a polyol compound and an isocyanate compound in advance and a polyol compound. Examples of polyurethanes include polyurethanes obtained by reacting a polyurethane compound obtained by reacting a polyol compound and an isocyanate compound in advance with moisture in the air and curing the polyurethane. As the polyol compound, it is preferable to use a polyester polyol having a hydroxyl group in a side chain in addition to the terminal hydroxyl group of the repeating unit. Examples of the second agent include aliphatic, alicyclic, aromatic, and araliphatic isocyanate compounds. Examples of isocyanate compounds include hexamethylene diisocyanate (HDI), xylylene diisocyanate (XDI), isophorone diisocyanate (IPDI), hydrogenated XDI (H6XDI), hydrogenated MDI (H12MDI), tolylene diisocyanate (TDI), and diphenylmethane diisocyanate. (MDI), naphthalene diisocyanate (NDI), and the like. In addition, polyfunctional isocyanate-modified products of one or more of these diisocyanates are also included. Moreover, a polymer (for example, a trimer) can also be used as a polyisocyanate compound. Such multimers include adducts, biurets, nurates and the like. Since the adhesive layer 2 is made of polyurethane, the exterior material for an electric storage device is endowed with excellent electrolyte resistance, and even if the electrolyte adheres to the side surface, the base layer 1 is suppressed from being peeled off.

In addition, the adhesive layer 2 may contain other components as long as they do not impede adhesion, and may contain colorants, thermoplastic elastomers, tackifiers, fillers, and the like. Since the adhesive layer 2 contains a coloring agent, the exterior material for an electric storage device can be colored. Known substances such as pigments and dyes can be used as the colorant. In addition, 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 organic pigments include azo-based, phthalocyanine-based, quinacridone-based, anthraquinone-based, dioxazine-based, indigothioindigo-based, perinone-perylene-based, isoindolenine-based, and benzimidazolone-based pigments. Examples of pigments include carbon black, titanium oxide, cadmium, lead, chromium oxide, and iron pigments, as well as fine powder of mica and fish scale foil.

Among the coloring agents, carbon black is preferable, for example, in order to make the external appearance of the exterior material for a power storage device black.

The average particle size of the pigment is not particularly limited, and is, 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 with a laser diffraction/scattering particle size distribution analyzer.

The content of the pigment in the adhesive layer 2 is not particularly limited as long as the power storage device exterior material is colored, and is, for example, 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 substrate layer 1 and the barrier layer 3 can be adhered, but is, for example, about 1 μm or more, or about 2 μm or more. Moreover, the thickness of the adhesive layer 2 is, for example, about 10 μm or less, or about 5 μm or less. Moreover, the preferable range of the thickness of the adhesive layer 2 is about 1 to 10 μm, about 1 to 5 μm, about 2 to 10 μm, and about 2 to 5 μm.

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

The colored layer can be formed, for example, by applying ink containing a coloring agent to the surface of the base material layer 1 or the surface of the barrier layer 3 . Known substances such as pigments and dyes can be used as the colorant. In addition, 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 colored layer are the same as those exemplified in the [Adhesive layer 2] column.

[Barrier layer 3]
In the power storage device exterior material, the barrier layer 3 is a layer that at least prevents permeation of moisture. In the exterior material for an electric storage device, it is preferable that the barrier layer 3 is one layer.

Examples of the barrier layer 3 include a metal foil, vapor deposition film, and resin layer having barrier properties. Examples of vapor-deposited films include metal vapor-deposited films, inorganic oxide vapor-deposited films, and carbon-containing inorganic oxide vapor-deposited films. Polymers containing fluoroethylene (TFE) as a main component, polymers having a fluoroalkyl group, fluorine-containing resins such as polymers containing fluoroalkyl units as a main component, and ethylene vinyl alcohol copolymers. The barrier layer 3 may also include a resin film provided with at least one of these deposited films and resin layers. 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 that constitutes the barrier layer 3 include aluminum alloys, stainless steels, titanium steels, and steel plates. When used as a metal foil, at least one of an aluminum alloy foil and a stainless steel foil is included. is preferred.

The aluminum alloy foil is more preferably a soft aluminum alloy foil made of, for example, an annealed aluminum alloy, from the viewpoint of improving the formability of the exterior material for an electricity storage device, and from the viewpoint of further improving the formability. Therefore, it is preferably an aluminum alloy foil containing iron. In the aluminum alloy foil containing iron (100% by mass), the iron content is preferably 0.1 to 9.0% by mass, 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 exterior material for an electricity storage device having superior moldability. When the iron content is 9.0% by mass or less, it is possible to obtain an exterior material for an electricity storage device that is more excellent in flexibility. As the soft aluminum alloy foil, for example, an aluminum alloy having a composition specified by JIS H4160: 1994 A8021H-O, JIS H4160: 1994 A8079H-O, JIS H4000: 2014 A8021P-O, or JIS H4000: 2014 A8079P-O foil. Moreover, silicon, magnesium, copper, manganese, etc. may be added as needed. Moreover, softening can be performed by annealing treatment or the like.

In addition, examples of stainless steel foils include austenitic, ferritic, austenitic/ferritic, martensitic, and precipitation hardened stainless steel foils. Furthermore, from the viewpoint of providing an exterior material for an electricity storage device with excellent formability, the stainless steel foil is preferably made of austenitic stainless steel.

Specific examples of the austenitic stainless steel that constitutes the stainless steel foil include SUS304, SUS301, SUS316L, etc. Among these, SUS304 is particularly preferable.

In the case of a metal foil, the thickness of the barrier layer 3 should be at least as long as it functions as a barrier layer that suppresses the intrusion of moisture. The thickness of the barrier layer 3 is preferably about 85 μm or less, more preferably about 50 μm or less, even more preferably about 40 μm or less, particularly preferably about 35 μm or less. Also, the thickness of the barrier layer 3 is preferably about 10 μm or more, more preferably about 20 μm or more, and more preferably about 25 μm or more. The preferred range of thickness of the barrier layer 3 is about 10 to 85 μm, about 10 to 50 μm, about 10 to 40 μm, about 10 to 35 μm, about 20 to 85 μm, about 20 to 50 μm, about 20 to 40 μm, 20 to 40 μm. About 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 preferred. In particular, when the barrier layer 3 is made of stainless steel foil, the thickness of the stainless steel foil is preferably about 60 μm or less, more preferably about 50 μm or less, even more preferably about 40 μm or less, and even more preferably about 30 μm. Below, it is particularly preferably about 25 μm or less. Also, the thickness of the stainless steel foil is preferably about 10 μm or more, more preferably about 15 μm or more. In addition, the preferable range of the thickness of the stainless steel foil is about 10 to 60 μm, about 10 to 50 μm, about 10 to 40 μm, about 10 to 30 μm, about 10 to 25 μm, about 15 to 60 μm, about 15 to 50 μm, 15 to 50 μm. About 40 μm, about 15 to 30 μm, and about 15 to 25 μm can be mentioned.

In addition, when the barrier layer 3 is a metal foil, it is preferable that at least the surface opposite to the base layer is provided with a corrosion-resistant film in order to prevent dissolution and corrosion. The barrier layer 3 may be provided with a corrosion resistant coating on both sides. Here, the corrosion-resistant film includes, for example, hydrothermal transformation treatment such as boehmite treatment, chemical conversion treatment, anodizing treatment, plating treatment such as nickel and chromium, and corrosion prevention treatment such as applying a coating agent to the surface of the barrier layer. It is a thin film that provides corrosion resistance (for example, acid resistance, alkali resistance, etc.) to the barrier layer. The corrosion-resistant film specifically means a film that improves the acid resistance of the barrier layer (acid-resistant film), a film that improves the alkali resistance of the barrier layer (alkali-resistant film), and the like. As the treatment for forming the corrosion-resistant film, one type may be performed, or two or more types may be used in combination. Also, not only one layer but also multiple layers can be used. Furthermore, among these treatments, the hydrothermal transformation treatment and the anodizing treatment are treatments in which the surface of the metal foil is dissolved with a treating agent to form a metal compound having excellent corrosion resistance. These treatments are sometimes included in the definition of chemical conversion treatment. When the barrier layer 3 has a corrosion-resistant film, the barrier layer 3 includes the corrosion-resistant film.

The corrosion-resistant coating prevents delamination between the barrier layer (e.g., aluminum alloy foil) and the substrate layer during the molding of the exterior material for power storage devices, and the hydrogen fluoride generated by the reaction between the electrolyte and moisture. , the dissolution and corrosion of the barrier layer surface, especially when the barrier layer is an aluminum alloy foil, the aluminum oxide present on the barrier layer surface is prevented from dissolving and corroding, and the adhesion (wettability) of the barrier layer surface is improved. , and exhibits the effect of preventing delamination between the base material layer and the barrier layer during heat sealing and preventing delamination between the base material layer and the barrier layer during molding.

Various types of corrosion-resistant coatings formed by chemical conversion treatment are known, and are mainly composed of at least one of phosphates, chromates, fluorides, triazinethiol compounds, and rare earth oxides. and corrosion-resistant coatings containing. Examples of chemical conversion treatments using phosphate and chromate include chromic acid chromate treatment, phosphoric acid chromate treatment, phosphoric acid-chromate treatment, and chromate treatment. Examples of compounds include chromium nitrate, chromium fluoride, chromium sulfate, chromium acetate, chromium oxalate, chromium biphosphate, chromium acetyl acetate, chromium chloride, potassium chromium sulfate, and the like. Phosphorus compounds used for these treatments include sodium phosphate, potassium phosphate, ammonium phosphate, polyphosphoric acid, and the like. Examples of the chromate treatment include etching chromate treatment, electrolytic chromate treatment, coating-type chromate treatment, etc., and coating-type chromate treatment is preferred. In this coating-type chromate treatment, at least the inner layer side surface of the barrier layer (for example, aluminum alloy foil) is first subjected to a well-known method such as an alkali immersion method, an electrolytic cleaning method, an acid cleaning method, an electrolytic acid cleaning method, an acid activation method, or the like. After degreasing by a treatment method, metal phosphate such as Cr (chromium) phosphate, Ti (titanium) phosphate, Zr (zirconium) phosphate, Zn (zinc) phosphate is applied to the degreased surface. A processing solution mainly composed of a salt and a mixture of these metal salts, a processing solution mainly composed of a non-metal phosphate salt and a mixture of these non-metal salts, or a mixture of these and a synthetic resin. This is a treatment in which a treatment liquid composed of a mixture is applied by a well-known coating method such as a roll coating method, a gravure printing method, or an immersion method, and then dried. Various solvents such as water, alcohol-based solvents, hydrocarbon-based solvents, ketone-based solvents, ester-based solvents, and ether-based solvents can be used as the treatment liquid, and water is preferred. In addition, the resin component used at this time includes polymers such as phenolic resins and acrylic resins. and the chromate treatment used. In the aminated phenol polymer, the repeating units represented by the following general formulas (1) to (4) may be contained singly or in any combination of two or more. good too. The acrylic resin is polyacrylic acid, acrylic acid methacrylic acid ester copolymer, acrylic acid maleic acid copolymer, acrylic acid styrene copolymer, or derivatives thereof such as sodium salts, ammonium salts, and amine salts. is preferred. In particular, derivatives of polyacrylic acid such as ammonium salt, sodium salt or amine salt of polyacrylic acid are preferred. In the present disclosure, polyacrylic acid means a polymer of acrylic acid. Further, the acrylic resin is preferably a copolymer of acrylic acid and dicarboxylic acid or dicarboxylic anhydride, and the ammonium salt, sodium salt, Alternatively, it is also preferably an amine salt. Only one type of acrylic resin may be used, or two or more types may be mixed and used.

In general formulas (1) to (4), X represents a hydrogen atom, hydroxy group, alkyl group, hydroxyalkyl group, allyl group or benzyl group. R ¹ and R ² are the same or different and represent a hydroxy group, an alkyl group or a hydroxyalkyl group. Examples of alkyl groups represented by X, R ¹ and R ² in general formulas (1) to (4) include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, A linear or branched alkyl group having 1 to 4 carbon atoms such as a tert-butyl group can be mentioned. Examples of hydroxyalkyl groups represented by X, R ¹ and R ² include hydroxymethyl group, 1-hydroxyethyl group, 2-hydroxyethyl group, 1-hydroxypropyl group, 2-hydroxypropyl group, 3- A straight or branched chain having 1 to 4 carbon atoms substituted with one hydroxy group such as hydroxypropyl group, 1-hydroxybutyl group, 2-hydroxybutyl group, 3-hydroxybutyl group and 4-hydroxybutyl group An alkyl group is mentioned. In general formulas (1) to (4), the alkyl groups and hydroxyalkyl groups represented by X, R ¹ and R ² may be the same or different. In general formulas (1) to (4), X is preferably a hydrogen atom, a hydroxy group or a hydroxyalkyl group. The number average molecular weight of the aminated phenol polymer having repeating units represented by formulas (1) to (4) is, for example, preferably about 500 to 1,000,000, more preferably about 1,000 to 20,000. more preferred. The aminated phenol polymer is produced, for example, by polycondensing a phenol compound or naphthol compound and formaldehyde to produce a polymer comprising repeating units represented by the general formula (1) or general formula (3), followed by formaldehyde. and an amine (R ¹ R ² NH) to introduce a functional group (--CH ₂ NR ¹ R ² ) into the polymer obtained above. An aminated phenol polymer is used individually by 1 type or in mixture of 2 or more types.

Another example of the corrosion-resistant film is formed by a coating-type corrosion prevention treatment in which a coating agent containing at least one selected from the group consisting of rare earth element oxide sol, anionic polymer, and cationic polymer is applied. A thin film that is The coating agent may further contain phosphoric acid or a phosphate, a cross-linking agent for cross-linking the polymer. In the rare earth element oxide sol, rare earth element oxide fine particles (for example, particles having an average particle size of 100 nm or less) are dispersed in a liquid dispersion medium. Examples of rare earth element oxides include cerium oxide, yttrium oxide, neodymium oxide, and lanthanum oxide, and cerium oxide is preferable from the viewpoint of further improving adhesion. The rare earth element oxides contained in the corrosion-resistant coating can be used singly or in combination of two or more. As the liquid dispersion medium for the rare earth element oxide sol, various solvents such as water, alcohol solvents, hydrocarbon solvents, ketone solvents, ester solvents, and ether solvents can be used, with water being preferred. Examples of the cationic polymer include polyethyleneimine, an ionic polymer complex composed of a polymer containing polyethyleneimine and carboxylic acid, a primary amine-grafted acrylic resin obtained by graft-polymerizing a primary amine to an acrylic backbone, polyallylamine, or a derivative thereof. , aminated phenols and the like are preferred. The anionic polymer is preferably poly(meth)acrylic acid or a salt thereof, or a copolymer containing (meth)acrylic acid or a salt thereof as a main component. Moreover, the cross-linking agent is preferably at least one selected from the group consisting of a compound having a functional group such as an isocyanate group, a glycidyl group, a carboxyl group, or an oxazoline group, and a silane coupling agent. Further, the phosphoric acid or phosphate is preferably condensed phosphoric acid or condensed phosphate.

As an example of the corrosion-resistant film, fine particles of metal oxides such as aluminum oxide, titanium oxide, cerium oxide, and tin oxide, and barium sulfate are dispersed in phosphoric acid, which is applied to the surface of the barrier layer. C. or more, and those formed by performing baking processing are mentioned.

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

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

The amount of the corrosion ^- resistant film formed on the surface of the barrier layer 3 in the chemical conversion treatment is not particularly limited. is about 0.5 to 50 mg, preferably about 1.0 to 40 mg in terms of chromium, the phosphorus compound is about 0.5 to 50 mg, preferably about 1.0 to 40 mg in terms of phosphorus, and aminated phenol polymer is contained in a ratio of, for example, about 1.0 to 200 mg, preferably about 5.0 to 150 mg.

The thickness of the corrosion-resistant coating is not particularly limited, but is preferably about 1 nm to 20 μm, more preferably 1 nm to 100 nm, from the viewpoint of cohesion of the coating and adhesion to the barrier layer and the heat-sealable resin layer. about 1 nm to 50 nm, more preferably about 1 nm to 50 nm. The thickness of the corrosion-resistant film can be measured by observation with a transmission electron microscope, or by a combination of observation with a transmission electron microscope and energy dispersive X-ray spectroscopy or electron beam energy loss spectroscopy. By analysis of the composition of the corrosion-resistant coating using time-of-flight secondary ion mass spectrometry, for example, secondary ions composed of Ce, P and O (for example, at least one of Ce ₂ PO ₄ ⁺ and CePO ₄ ⁻ species) and, for example, secondary ions composed of Cr, P, and O (eg, at least one of CrPO ₂ ⁺ and CrPO ₄ ⁻ ) are detected.

Chemical conversion treatment involves applying a solution containing a compound used to form a corrosion-resistant film to the surface of the barrier layer by a bar coating method, roll coating method, gravure coating method, immersion method, etc., and then changing the temperature of the barrier layer. is carried out by heating so that the temperature is about 70 to 200°C. In addition, before the barrier layer is subjected to the chemical conversion treatment, the barrier layer may be previously subjected to a degreasing treatment by an alkali immersion method, an electrolytic cleaning method, an acid cleaning method, an electrolytic acid cleaning method, or the like. By performing the degreasing treatment in this way, it becomes possible to perform the chemical conversion treatment on the surface of the barrier layer more efficiently. In addition, by using an acid degreasing agent obtained by dissolving a fluorine-containing compound in an inorganic acid for degreasing treatment, it is possible to form not only the degreasing effect of the metal foil but also the passive metal fluoride. In such cases, only degreasing treatment may be performed.

[Heat-fusible resin layer 4]
In the power storage device exterior material of the present disclosure, the heat-fusible resin layer 4 corresponds to the innermost layer, and has the function of sealing the power storage device element by heat-sealing the heat-fusible resin layers to each other when assembling the power storage device. It is a layer (sealant layer) that exhibits

The resin constituting the heat-fusible resin layer 4 is not particularly limited as long as it is heat-fusible, but resins containing polyolefin skeletons such as polyolefins and acid-modified polyolefins are preferable. The inclusion of a polyolefin skeleton in the resin constituting the heat-fusible resin layer 4 can be analyzed by, for example, infrared spectroscopy, gas chromatography-mass spectrometry, or the like. Further, when the resin constituting 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 maleic anhydride-modified polyolefin is measured by infrared spectroscopy, peaks derived from maleic anhydride are detected near wavenumbers of 1760 cm ⁻¹ and 1780 cm ⁻¹ . In the case where the heat-fusible resin layer 4 is a layer composed of maleic anhydride-modified polyolefin, a peak derived from maleic anhydride is detected when measured by infrared spectroscopy. However, if the degree of acid denaturation 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 polyolefins include polyethylenes such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; ethylene-α-olefin copolymers; block copolymers of ethylene), random copolymers of polypropylene (for example, random copolymers of propylene and ethylene); propylene-α-olefin copolymers; ethylene-butene-propylene terpolymers; Among these, polypropylene is preferred. When the polyolefin resin is a copolymer, it may be a block copolymer or a random copolymer. These polyolefin-based resins may be used alone or in combination of two or more.

Also, the polyolefin may be a cyclic polyolefin. A cyclic polyolefin is a copolymer of an olefin and a cyclic monomer. Examples of the olefin, which is a constituent monomer of the cyclic polyolefin, include ethylene, propylene, 4-methyl-1-pentene, styrene, butadiene, and isoprene. be done. Examples of cyclic monomers constituting cyclic polyolefins include cyclic alkenes such as norbornene; cyclic dienes such as cyclopentadiene, dicyclopentadiene, cyclohexadiene and norbornadiene. Among these, cyclic alkenes are preferred, and norbornene is more preferred.

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

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

Preferable acid-modified polyolefins include polyolefins modified with carboxylic acid or its anhydride, polypropylene modified with carboxylic acid or its anhydride, maleic anhydride-modified polyolefin, and maleic anhydride-modified polypropylene.

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 resin are combined. Furthermore, the heat-fusible resin layer 4 may be formed of only one layer, or may be formed of two or more layers of the same or different resins.

In addition, the heat-fusible resin layer 4 may contain a lubricant or the like as necessary. When the heat-fusible resin layer 4 contains a lubricant, it is possible to improve the moldability of the power storage device exterior material. The lubricant is not particularly limited, and known lubricants can be used. Lubricants may be used singly or in combination of two or more.

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

When a lubricant exists on the surface of the heat-sealable resin layer 4, the amount of the lubricant is not particularly limited, but from the viewpoint of improving the moldability of the exterior material for an electricity storage device, the amount 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 obtained by exuding the lubricant contained in the resin constituting the heat-fusible resin layer 4 . 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 are heat-sealed to each other to exhibit the function of sealing the electricity storage device element. 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, more preferably about 15 to 45 μm. When the thickness of the adhesive layer 5 described later 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, more preferably 35 to 85 μm. degree.

[Adhesion layer 5]
In the power storage device exterior material of the present disclosure, the adhesive layer 5 is provided between the barrier layer 3 (or the corrosion-resistant film) and the heat-fusible resin layer 4 as necessary in order to firmly bond them. It is a layer that can be

The adhesive layer 5 is made of a resin that can bond the barrier layer 3 and the heat-fusible resin layer 4 together. 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. Further, from the viewpoint of firmly bonding the adhesive layer 5 and the heat-fusible resin layer 4, it is preferable that the resin used for forming the adhesive layer 5 contains a polyolefin skeleton. Polyolefins and acid-modified polyolefins exemplified for the resin layer 4 can be used. On the other hand, from the viewpoint of firmly bonding the barrier layer 3 and the adhesive layer 5, the adhesive layer 5 preferably contains an acid-modified polyolefin. Acid-modified components include dicarboxylic acids such as maleic acid, itaconic acid, succinic acid and adipic acid, their anhydrides, acrylic acid and methacrylic acid. Maleic acid is most preferred. Moreover, from the viewpoint of heat resistance of the exterior material for an electric storage device, the olefin component is preferably a polypropylene-based resin, and the adhesive layer 5 most preferably contains maleic anhydride-modified polypropylene.

Whether the resin constituting the adhesive layer 5 contains a polyolefin skeleton can be analyzed by, for example, infrared spectroscopy, gas chromatography mass spectrometry, or the like, and the analysis method is not particularly limited. Further, the fact that the resin constituting the adhesive layer 5 contains an acid ^- modified polyolefin means that, for example, when the maleic anhydride ^- modified polyolefin is measured by infrared spectroscopy, anhydrous A peak derived from maleic acid is detected. However, if the degree of acid denaturation is low, the peak may be too small to be detected. In that case, it can be analyzed by nuclear magnetic resonance spectroscopy.

Furthermore, from the viewpoint of ensuring durability such as heat resistance and content resistance of the exterior material for an electric storage device and moldability while reducing the thickness, the adhesive layer 5 is made of a resin composition containing an acid-modified polyolefin and a curing agent. A cured product is more preferred. Preferred examples of the acid-modified polyolefin include those mentioned above.

Further, the adhesive layer 5 is a cured product of a resin composition containing 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. 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 and a compound having an epoxy group is particularly preferred. Moreover, 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 ester resin produced by a reaction between an epoxy group and a maleic anhydride group, and an amide ester resin produced by a reaction between an oxazoline group and a maleic anhydride group are preferable. In the case where the adhesive layer 5 contains an isocyanate group-containing compound, an oxazoline group-containing compound, or an unreacted product of a curing agent such as an epoxy resin, the presence of the unreacted product can be detected by, for example, infrared spectroscopy, It can be confirmed by a method selected from Raman spectroscopy, time-of-flight secondary ion mass spectrometry (TOF-SIMS), and the like.

In addition, from the viewpoint of further increasing the adhesion between the barrier layer 3 and the adhesive layer 5, the adhesive layer 5 contains at least It is preferably a cured product of a resin composition containing one curing agent. The curing agent having a heterocyclic ring includes, for example, a curing agent having an oxazoline group, a curing agent having an epoxy group, and the like. Moreover, the curing agent having a C═N bond includes a curing agent having an oxazoline group, a curing agent having an isocyanate group, and the like. Further, the curing agent having a C—O—C bond includes a curing agent having an oxazoline group, a curing agent having an epoxy group, and the like. The adhesive layer 5 is a cured product of a resin composition containing these curing agents, for example, gas chromatography mass spectrometry (GCMS), infrared spectroscopy (IR), time-of-flight secondary ion mass spectrometry (TOF -SIMS) and X-ray photoelectron spectroscopy (XPS).

The compound having an isocyanate group is not particularly limited, but from the viewpoint of effectively increasing the adhesion between the barrier layer 3 and the adhesive layer 5, polyfunctional isocyanate compounds are preferred. The polyfunctional isocyanate compound is not particularly limited as long as it is a compound having two or more isocyanate groups. Specific examples of polyfunctional isocyanate curing agents include pentane diisocyanate (PDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), polymerization and nurate compounds, mixtures thereof, copolymers with other polymers, and the like. In addition, adducts, biurets, isocyanurates and the like are included.

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, more preferably 0.5 to 40% by mass in the resin composition constituting the adhesive layer 5. A range is more preferred. Thereby, the adhesion between the barrier layer 3 and the adhesive layer 5 can be effectively improved.

The compound having an oxazoline group is not particularly limited as long as it is a compound having an oxazoline skeleton. Specific examples of compounds having an oxazoline group include those having a polystyrene main chain and those having an acrylic main chain. Moreover, as a commercial item, the Epocross series by Nippon Shokubai Co., Ltd. etc. are mentioned, for example.

The ratio of the compound having an oxazoline group in the adhesive layer 5 is preferably in the range of 0.1 to 50% by mass, more preferably 0.5 to 40% by mass, in the resin composition constituting the adhesive layer 5. is more preferable. Thereby, the adhesion between the barrier layer 3 and the adhesive layer 5 can be effectively improved.

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 with epoxy groups present in the molecule, and known epoxy resins can be used. The weight average molecular weight of the epoxy resin is preferably about 50 to 2000, more preferably about 100 to 1000, still more preferably about 200 to 800. In the first disclosure, the weight average molecular weight of the epoxy resin is a value measured by gel permeation chromatography (GPC) under conditions using polystyrene as a standard sample.

Specific examples of epoxy resins include glycidyl ether derivatives of trimethylolpropane, bisphenol A diglycidyl ether, modified bisphenol A diglycidyl ether, bisphenol F-type glycidyl ether, novolac glycidyl ether, glycerin polyglycidyl ether, polyglycerin polyglycidyl ether, and the like. are mentioned. An epoxy resin may be used individually by 1 type, and may be used in combination of 2 or more types.

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

The polyurethane is not particularly limited, and known polyurethanes 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, more preferably in the range of 0.5 to 40% by mass, in the resin composition constituting the adhesive layer 5. more preferred. As a result, the adhesion between the barrier layer 3 and the adhesive layer 5 can be effectively enhanced in an atmosphere containing a component that induces corrosion of the barrier layer, such as an electrolytic solution.

In addition, 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 a 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 adhesive layer 5 may contain a modifier having a carbodiimide group.

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, or about 5 μm or less. Also, the thickness of the adhesive layer 5 is preferably about 0.1 μm or more and about 0.5 μm or more. The thickness range of the adhesive layer 5 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, and about 0.1 to 5 μm. , about 0.5 to 50 μm, about 0.5 to 40 μm, about 0.5 to 30 μm, about 0.5 to 20 μm, and about 0.5 to 5 μm. More specifically, in the case of the adhesive exemplified for the adhesive layer 2 or the cured product of acid-modified polyolefin and curing agent, the thickness is preferably about 1 to 10 μm, more preferably about 1 to 5 μm. In the case of using the resin exemplified for the heat-fusible resin layer 4, the thickness is preferably about 2 to 50 μm, more preferably about 10 to 40 μm. When the adhesive layer 5 is the adhesive exemplified for the adhesive layer 2 or a cured product of 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. Thus, the adhesive layer 5 can be formed. Further, when using the resin exemplified for the heat-fusible resin layer 4, the heat-fusible resin layer 4 and the adhesive layer 5 can be formed by extrusion molding, for example.

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

Examples of the surface coating layer 6 include resins such as polyvinylidene chloride, polyester, polyamide, epoxy resin, acrylic resin, fluororesin, polyurethane, silicon resin, phenolic resin, and modified products of these resins. Copolymers of these resins or modified copolymers may also be used. Furthermore, it may be a mixture of these resins. The resin is preferably a curable resin. That is, the surface coating layer 6 is preferably made of a cured product of a resin composition containing a curable resin.

When the resin forming the surface coating layer 6 is a curable resin, the resin may be either a one-liquid curable type or a two-liquid curable type, preferably the two-liquid curable type. Examples of the two-liquid curing resin include two-liquid curing polyurethane, two-liquid curing polyester, and two-liquid curing epoxy resin. Among these, two-liquid curable polyurethane is preferred.

Examples of two-liquid curable polyurethanes include polyurethanes containing a first agent containing a polyol compound and a second agent containing an isocyanate compound. Preferred examples include a two-component curing type polyurethane in which a polyol such as polyester polyol, polyether polyol, or acrylic polyol is used as the first agent and an aromatic or aliphatic polyisocyanate is used as the second agent. Examples of polyurethane include polyurethane containing a polyurethane compound obtained by reacting a polyol compound and an isocyanate compound in advance and an isocyanate compound. Examples of polyurethane include polyurethane containing a polyurethane compound obtained by reacting a polyol compound and an isocyanate compound in advance and a polyol compound. Examples of polyurethanes include polyurethanes obtained by reacting a polyurethane compound obtained by reacting a polyol compound and an isocyanate compound in advance with moisture in the air and the like to cure the compound. As the polyol compound, it is preferable to use a polyester polyol having a hydroxyl group in a side chain in addition to the terminal hydroxyl group of the repeating unit. Examples of the second agent include aliphatic, alicyclic, aromatic, and araliphatic isocyanate compounds. Examples of isocyanate compounds include hexamethylene diisocyanate (HDI), xylylene diisocyanate (XDI), isophorone diisocyanate (IPDI), hydrogenated XDI (H6XDI), hydrogenated MDI (H12MDI), tolylene diisocyanate (TDI), and diphenylmethane diisocyanate. (MDI), naphthalene diisocyanate (NDI), and the like. In addition, polyfunctional isocyanate-modified products of one or more of these diisocyanates are also included. Moreover, a polymer (for example, a trimer) can also be used as a polyisocyanate compound. Such multimers include adducts, biurets, nurates and the like. In addition, the aliphatic isocyanate compound refers to an isocyanate having an aliphatic group and no aromatic ring, and the alicyclic isocyanate compound refers to an isocyanate having an alicyclic hydrocarbon group, and the aromatic isocyanate compound refers to an isocyanate having an aromatic ring. Since the surface coating layer 6 is made of polyurethane, the exterior material for an electric storage device is imparted with excellent electrolyte resistance.

At least one of the surface and the inside of the surface coating layer 6 may be coated with the above-described lubricant or anti-rust agent as necessary depending on the functionality to be provided on the surface coating layer 6 and its surface. Additives such as blocking agents, matting agents, flame retardants, antioxidants, tackifiers and antistatic agents may be included. Examples of the additive include fine particles having an average particle size of about 0.5 nm to 5 μm. The average particle size of the additive is the median size measured with a laser diffraction/scattering particle size distribution analyzer.

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

Specific examples of additives include talc, silica, graphite, kaolin, montmorillonite, mica, hydrotalcite, silica gel, zeolite, aluminum hydroxide, magnesium hydroxide, zinc oxide, magnesium oxide, aluminum oxide, neodymium oxide, and 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 nanotube, high melting point nylon, acrylate resin, Crosslinked acrylic, crosslinked styrene, crosslinked polyethylene, benzoguanamine, gold, aluminum, copper, nickel, and the like. Additives may be used singly or in combination of two or more. Among these additives, silica, barium sulfate, and titanium oxide are preferred from the viewpoint of dispersion stability and cost. In addition, the additive may be subjected to various surface treatments such as insulation treatment and high-dispersion treatment.

The method of forming the surface coating layer 6 is not particularly limited, and for example, a method of applying a resin for forming the surface coating layer 6 can be used. When adding additives to the surface coating layer 6, a resin mixed with the additives may be applied.

The thickness of the surface coating layer 6 is not particularly limited as long as the above functions of the surface coating layer 6 are exhibited.

4. Method for Producing Exterior Material for Electricity Storage Device The method for producing the exterior material for an electricity storage device of the present disclosure is not particularly limited as long as a laminate obtained by laminating each layer included in the exterior material for an electricity storage device of the present invention is obtained. The adhesive layer 2 is formed so as to satisfy the porosity of . Specifically, the method for manufacturing the exterior material 10 for an electricity storage device of the present disclosure is as follows. The details of each layer of the laminate constituting the exterior material for an electricity storage device, the details of the porosity, etc. are as described above.

preparing a film-like laminate comprising at least a substrate layer, an adhesive layer, a barrier layer, and a heat-fusible resin layer in this order;
A step of molding the laminate so as to protrude from the heat-fusible resin layer side to the base layer side, and forming a recess in which an electricity storage device element is housed on the heat-fusible resin layer side. and
A method for producing an exterior material for an electric storage device, wherein the cross section of the adhesive layer in the thickness direction has a porosity of 25% or less observed at a magnification of 150 times with an objective lens.

As described above, in the power storage device exterior material 10 of the present disclosure, in order to form the adhesive layer 2 so as to have the above-described porosity, it is necessary to select not only the type of adhesive but also the base layer 1 and the barrier layer. When laminating the layer 3 with the adhesive layer 2 interposed therebetween, it is required to design the adhesive layer 2 so as not to generate air bubbles as much as possible. For example, by increasing the lamination pressure when laminating the base material layer 1 and the barrier layer 3 with the adhesive layer 2 interposed therebetween, air trapped in the adhesive layer 2 when the base material layer 1 and the barrier layer 3 are laminated. is crushed to reduce the air remaining in the adhesive layer 2, thereby suppressing the generation of voids. In addition, by increasing the diameter of the nip roll used when laminating the base layer 1 and the barrier layer 3 with the adhesive layer 2 interposed therebetween, the adhesive layer 1 and the barrier layer 3 are laminated together. A method of suppressing the generation of voids by increasing the time and area for crushing the air caught in the adhesive layer 2 and reducing the air remaining in the adhesive layer 2 can be mentioned. Furthermore, when laminating the base material layer 1 and the barrier layer 3 with the adhesive layer 2 interposed therebetween, the base material layer 1 is laminated after the adhesive for forming the adhesive layer 2 is applied to the surface of the barrier layer 3. By doing so, the air caught in the lamination of the base material layer 1 gradually volatilizes from the side of the base material layer 1 after lamination, so that the generation of voids can be suppressed. In addition, when the barrier layer 3 is laminated after the adhesive for forming the adhesive layer 2 is applied to the surface of the base material layer 1, the air taken in when laminating the barrier layer 3 is Since the adhesive cannot volatilize from the side, voids are more likely to be formed in the adhesive layer 2 than in the case where the adhesive is applied to the surface of the barrier layer 3 . That is, when the barrier layer 3 is laminated after the adhesive for forming the adhesive layer 2 is applied to the surface of the base material layer 1, the air caught in the lamination of the barrier layer 3 volatilizes from the barrier layer 3 side. As shown in the schematic diagrams of FIGS. 9 and 10, voids 2a are likely to be formed on the barrier layer side. On the other hand, when the adhesive for forming the adhesive layer 2 is applied to the surface of the barrier layer 3 and then the substrate layer 1 is laminated, voids are likely to be formed on the substrate layer side, and volatilization is likely to occur as described above. The generation of voids is suppressed, or if they are formed, they are of small size. Moreover, in the power storage device exterior material 10 of the present disclosure, in order to form the adhesive layer 2 so as to have the above-described porosity, the barrier layer 3 is preferably one layer.

An example of a method for manufacturing a film-like laminate that constitutes the exterior material for an electricity storage device of the present disclosure is as follows. First, a layered body (hereinafter also referred to as "layered body A") is formed by laminating a substrate layer 1, an adhesive layer 2, and a barrier layer 3 in this order. Specifically, the laminate A is formed by applying an adhesive used for forming the adhesive layer 2 on the substrate layer 1 or on the barrier layer 3 whose surface is chemically treated as necessary, by a gravure coating method, It can be performed by a dry lamination method in which the barrier layer 3 or the substrate layer 1 is laminated and the adhesive layer 2 is cured after coating and drying by a coating method such as a roll coating method. The technique for reducing the porosity of the adhesive layer 2 is as described above.

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 thermal lamination or extrusion lamination. 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 placed on the barrier layer 3 of the laminate A. 4 (co-extrusion lamination method, tandem lamination method); A method of laminating on the barrier layer 3 of the laminate A by a thermal lamination method, or forming a laminate in which an adhesive layer 5 is laminated on the barrier layer 3 of the laminate A, and laminating this with a heat-fusible resin layer 4 by a thermal lamination method Lamination method (3) While pouring the melted adhesive layer 5 between the barrier layer 3 of the laminate A and the heat-fusible resin layer 4 formed into a sheet in advance, the adhesive layer 5 is interposed. (4) coating the barrier layer 3 of the laminate A with an adhesive for forming the adhesive layer 5 in solution, A drying method, a baking method, or the like is used to laminate the adhesive layer 5 , and a heat-fusible resin layer 4 that has been formed into a sheet in advance is laminated on the adhesive layer 5 .

When the surface coating layer 6 is provided, the surface coating layer 6 is laminated on the surface of the substrate layer 1 opposite to the barrier layer 3 . The surface coating layer 6 can be formed, for example, by coating the surface of the substrate layer 1 with the above-described resin for forming the surface coating layer 6 . 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 substrate layer 1 , the barrier layer 3 may be formed on the surface of the substrate layer 1 opposite to the surface coating layer 6 .

As described above, the optionally provided surface coating layer 6/base layer 1/adhesive layer 2/barrier layer 3/optionally provided adhesive layer 5/heat-fusible resin layer 4 are combined into this layer. A laminated body is formed in order, and in order to strengthen the adhesiveness of the adhesive layer 2 and the adhesive layer 5 provided as necessary, it may be further subjected to a 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, blasting treatment, oxidation treatment, and ozone treatment to improve processability as necessary. . For example, by subjecting the surface of the substrate layer 1 opposite to the barrier layer 3 to corona treatment, the printability of the ink onto the surface of the substrate layer 1 can be improved.

5. Electricity Storage Device The exterior material for an electricity storage device of the present disclosure is used in a package for sealingly housing electricity storage device elements such as a positive electrode, a negative electrode, and an electrolyte. That is, an electricity storage device can be obtained by housing an electricity storage device element including at least a positive electrode, a negative electrode, and an electrolyte in a package formed by the electricity storage device exterior material of the present disclosure.

Specifically, an electricity storage device element having at least a positive electrode, a negative electrode, and an electrolyte is placed in the exterior material for an electricity storage device of the present disclosure in a state in which metal terminals connected to the positive electrode and the negative electrode protrude outward. , covering the periphery of the electricity storage device element so as to form a flange portion (area where the heat-fusible resin layers contact each other), and heat-sealing the heat-fusible resin layers of the flange portion to seal. provides an electricity storage device using an exterior material for an electricity storage device. In addition, when housing an electricity storage device element in a package formed by 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 on the inside (surface in contact with the electricity storage device element ) to form a package.

The power storage device exterior material of the present disclosure can be suitably used for power storage devices such as batteries (including capacitors, capacitors, etc.). Moreover, although the exterior material for an electricity storage device of the present disclosure may be used for either a primary battery or a secondary battery, it is preferably a secondary battery. The type of secondary battery to which the power storage device exterior material of the present disclosure is applied is not particularly limited. Cadmium storage batteries, 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 can be mentioned as suitable targets for application of the power storage device exterior material of the present disclosure.

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

<Manufacturing exterior materials for power storage devices>
Examples 1-5 and Comparative Examples 1-2
As a substrate layer, a polyethylene terephthalate film (thickness 12 μm) and a biaxially oriented nylon film (thickness 15 μm) are bonded by a two-liquid curable polyurethane adhesive (using adhesives A to D described later). A laminated film was prepared by laminating agent layers (having a thickness of 3 μm after curing). Next, on the biaxially oriented nylon film of the substrate layer, a barrier layer composed of an aluminum alloy foil (thickness: 40 μm) with corrosion-resistant coatings formed on both sides was laminated by a dry lamination method. Specifically, after laminating the biaxially oriented nylon film side of the base layer and the aluminum alloy foil using a two-component curable polyurethane adhesive (each using adhesives A to D described later), A laminate of base material layer/adhesive layer/barrier layer was produced by performing an aging treatment. Of the conditions for laminating the base material layer and the barrier layer via an adhesive layer, conditions other than the type of adhesive (laminating pressure ratio, nip roll diameter ratio, and the surface to which the adhesive is applied (aluminum alloy foil or the surface of a biaxially oriented nylon film) is as described in Table 1.

<Conditions for Laminating the Base Material Layer and the Barrier Layer via the Adhesive Layer>
(type of adhesive)
Adhesive A: A two-component polyurethane adhesive using an aromatic isocyanate compound as a curing agent Adhesive B: A two-component polyurethane adhesive using an aromatic isocyanate compound as a curing agent (manufacturer different from adhesive A) made)
Adhesive C: Two-component polyurethane adhesive using an aromatic isocyanate compound as a curing agent (manufactured by a different manufacturer from Adhesives A and B)
Adhesive D: Two-component polyurethane adhesive using an aliphatic cyclic isocyanate compound as a curing agent (manufactured by the same manufacturer as Adhesive C)

Next, a maleic anhydride-modified polypropylene (40 μm thick) as an adhesive layer and a polypropylene (40 μm thick) as a heat-fusible resin layer were co-extruded onto the barrier layer side of the obtained laminate. An adhesive layer/heat-fusible resin layer was laminated on the barrier layer. Next, by aging and heating the obtained laminate, polyethylene terephthalate film (12 μm)/adhesive layer (3 μm)/biaxially oriented nylon film (15 μm)/adhesive layer (3 μm)/barrier layer ( 40 μm)/adhesive layer (40 μm)/heat-fusible resin layer (40 μm) laminated in this order to obtain a film-like laminate (total thickness: 153 μm).

Next, each laminate obtained was cut into strips of 150 mm (MD: Machine Direction) x 90 mm (TD: Transverse Direction). The MD of the laminate corresponds to the rolling direction (RD) of the aluminum alloy foil, and the TD of the laminate corresponds to the TD of the aluminum alloy foil. Next, a strip is placed between a molding die (female mold) having a diameter of 55 mm (MD) x 32 mm (TD) and a corresponding molding die (male mold) (the female mold side is the base layer side), and cold forming was performed with a pressing pressure of 0.9 MPa and a forming depth of 5.5 mm to obtain a formed exterior material for an electricity storage device (see FIGS. 4 and 5).

<Measurement of Porosity of Adhesive Layer>
The adhesive layer positioned between the substrate layer and the barrier layer (specifically, the biaxially stretched The porosity was measured for a cross section in the thickness direction of the adhesive layer that adheres the nylon film and the aluminum alloy foil).

As shown in the schematic diagrams of FIGS. 4 and 5 , when the power storage device exterior material is observed from the base layer side, the recess 100 (molding portion) formed in a substantially rectangular shape in plan view has a corner portion of the recess 100 . and the straight line forming the ridge (in FIG. 4, where the solid line indicating the recess 100 and the broken lines (1) to (8) intersect), the direction parallel to the thickness direction (further, cutting A cross section of the adhesive layer was obtained by cutting with a microtome (ROM-380 manufactured by Yamato Koki Kogyo Co., Ltd.). Note that when the power storage device exterior material is observed from the base layer side, the corners of the concave portions 100 do not form ideal right angles, but become curved. In this example and comparative example, the boundary portion between the curved line forming the corner portion of the recess 100 and the straight line forming the ridge portion (in FIG. ) was obtained. Then, since peeling is particularly likely to occur in a moist and hot environment, in the cross section, the bent portion 10A on the bottom surface 100A side (as shown in FIGS. 5 to 8, the bent portion formed by the male mold) and the sealing Of the bent portion 10B on the sealing edge 10C side (the bent portion formed by the female mold as shown in FIGS. 5 to 8), the cross section of the bent portion 10B on the sealing edge 10C side (region P in FIG. 5 ) was used as the measurement target for the porosity. Next, of the cross sections obtained for the adhesive layer, the cross section at the bent portion P (see FIG. 5) was observed using a laser microscope (VK-9710 manufactured by KEYENCE) with an objective lens of 150x magnification. rice field. Subsequently, from the cross-sectional observation results obtained, the area of the adhesive layer and the area of the voids were quantified using analysis software VK Analyzer version 2.5.0.1. Specifically, select the volume and area (V) of the evaluation analysis (A) of the VK Analyzer, select the "polygon" mode for the area of the adhesive layer, and all the adhesive layers represented in the acquired image By selecting 5 points between the barrier layer 3 (aluminum alloy foil) and the

adhesive layer

2 and 5 points between the adhesive layer 2 and the base layer 1 (biaxially oriented nylon film) so as to include , the area was measured (see the schematic diagram of FIG. 9. The area of the adhesive layer 2 including the voids 2a is the measurement target.). In addition, the "free line" mode was selected for the voids, and the areas were measured by enclosing them with lines so that the entire voids were filled (see the schematic diagram of FIG. 10. The area of the voids 2a is the measurement target.) . The ratio of the obtained areas was calculated by the following formula to obtain the cross-sectional porosity (%). Table 1 shows the value with the largest porosity among the eight measurement positions described above.
Porosity (%) of the cross section of the adhesive layer = (cross-sectional area of voids in the adhesive layer/cross-sectional area of the adhesive layer) x 100

<Evaluation of moist heat resistance>
16 pieces of each of the molded electrical storage device exterior materials obtained above were prepared as samples. Next, 16 samples are placed in a constant temperature bath at a temperature of 80 ° C. and a relative humidity of 90%, and the occurrence of peeling between the aluminum alloy foil and the biaxially oriented nylon film of the base layer is checked every day. was visually observed. Detachment of the biaxially oriented nylon film from the aluminum alloy foil was judged to have occurred when 1 mm or more was observed, and based on the number of days until detachment occurred for all 16 samples, moisture resistance was measured according to the following criteria. Thermal properties were evaluated. It can be said that it is a very severe evaluation to evaluate the heat and humidity resistance of the molded exterior material for an electricity storage device under conditions of a temperature of 80° C. and a relative humidity of 90%. Table 1 shows the results.
A+: 30 days or more until peeling occurs, most excellent in moist heat resistance A: 20 days or more and less than 30 days until peeling occurs, particularly excellent in moist heat resistance B: Until peeling occurs 10 days or more and less than 20 days, and fairly excellent moist heat resistance C: 5 days or more and less than 10 days until peeling occurs, and excellent moist heat resistance D: Less than 5 days until peeling occurs , Humidity and heat resistance equal to or lower than general standards

The exterior material for an electricity storage device of Examples 1 to 5 was formed into a film-like laminate comprising at least a substrate layer, an adhesive layer, a barrier layer, and a heat-fusible resin layer in this order. An exterior material for an electricity storage device, which is molded so as to protrude from the heat-fusible resin layer side to the base layer side, and has a concave portion for accommodating the electricity storage device element on the heat-fusible resin layer side. , the porosity of the cross section of the adhesive layer in the thickness direction observed at a magnification of 150 times of the objective lens is 25% or less. The power storage device exterior materials of Examples 1 to 5 were inhibited from peeling at the position of the adhesive layer of the power storage device exterior materials in a moist and heat environment, and exhibited excellent moist heat resistance. In Example 5 and Comparative Example 2 in which the adhesive was applied to the surface of the biaxially oriented nylon film, voids were formed on the barrier layer side of the adhesive layer as shown in the schematic diagrams of FIGS.

As described above, the present disclosure provides inventions in the following aspects.
Section 1. An exterior material for an electricity storage device, in which a film-like laminate is formed comprising at least a substrate layer, an adhesive layer, a barrier layer, and a heat-fusible resin layer in this order,
The power storage device exterior material is molded so as to protrude from the heat-fusible resin layer side to the base layer side, and has a recessed portion in which the power storage device element is accommodated on the heat-fusible resin layer side. and
An exterior material for an electric storage device, wherein the adhesive layer has a porosity of 25% or less in a cross-section in the thickness direction, as observed at a magnification of 150 times with an objective lens.
Section 2. Item 2. The exterior material for an electricity storage device according to Item 1, wherein the adhesive layer is formed of a cured product of a resin composition containing a curable resin.
Item 3. Item 3. The exterior material for an electricity storage device according to Item 2, wherein the resin composition is a two-component adhesive.
Section 4. Item 4. The exterior material for an electricity storage device according to

Item

2 or 3, wherein the resin composition contains polyurethane.
Item 5. Item 5. The exterior material for an electricity storage device according to any one of items 1 to 4, wherein the exterior material for an electricity storage device has a substantially rectangular shape in plan view.
Item 6. Item 6. The power storage device exterior material according to any one of Items 1 to 5, wherein the concave portion of the power storage device exterior material has a substantially rectangular shape in plan view.
Item 7. preparing a film-like laminate comprising at least a substrate layer, an adhesive layer, a barrier layer, and a heat-fusible resin layer in this order;
A step of molding the laminate so as to protrude from the heat-fusible resin layer side to the base layer side, and forming a recess in which an electricity storage device element is housed on the heat-fusible resin layer side. and
A method for producing an exterior material for an electric storage device, wherein the adhesive layer has a porosity of 25% or less in a cross-section in the thickness direction, as observed at a magnification of 150 times with an objective lens.
Item 8. An electricity storage device in which an electricity storage device element including at least a positive electrode, a negative electrode, and an electrolyte is housed in a package formed using an electricity storage device exterior material,
The exterior material for an electricity storage device is formed of a film-like laminate that includes at least a base layer, an adhesive layer, a barrier layer, and a heat-fusible resin layer in this order,
The power storage device exterior material is molded so as to protrude from the heat-fusible resin layer side to the base layer side, and has a recessed portion in which the power storage device element is accommodated on the heat-fusible resin layer side. and
The power storage device, wherein the adhesive layer has a porosity of 25% or less in a cross section in the thickness direction, as observed at a magnification of 150 times with an objective lens.
Item 9. An electricity storage device comprising a step of housing an electricity storage device element comprising at least a positive electrode, a negative electrode, and an electrolyte in a package formed using the electricity storage device exterior material according to any one of Items 1 to 6. manufacturing method.

1 Base material layer 2 Adhesive layer 2a Space 3 Barrier layer 4 Heat-fusible resin layer 5 Adhesive layer 6 Surface coating layer 10 Exterior material for electric storage device 10A Bending portion 10B on the bottom side of the recess Bending portion on the edge side for sealing 10C Sealing rim 21 Female die 22 Male die 23 Pressing plate 100 Recess 100A Bottom of recess

Claims

An exterior material for an electricity storage device, in which a film-like laminate is formed comprising at least a substrate layer, an adhesive layer, a barrier layer, and a heat-fusible resin layer in this order,
The power storage device exterior material is molded so as to protrude from the heat-fusible resin layer side to the base layer side, and has a recessed portion in which the power storage device element is accommodated on the heat-fusible resin layer side. and
An exterior material for an electric storage device, wherein the adhesive layer has a porosity of 25% or less in a cross-section in the thickness direction, as observed at a magnification of 150 times with an objective lens.
The exterior material for an electricity storage device according to claim 1, wherein the adhesive layer is formed of a cured resin composition containing a curable resin.
The exterior material for an electricity storage device according to claim 2, wherein the resin composition is a two-component adhesive.
The exterior material for an electricity storage device according to claim 2 or 3, wherein the resin composition contains polyurethane.
The exterior material for an electricity storage device according to any one of claims 1 to 4, wherein the exterior material for an electricity storage device has a substantially rectangular shape in plan view.
The power storage device exterior material according to any one of claims 1 to 5, wherein the concave portion of the power storage device exterior material has a substantially rectangular shape in plan view.
preparing a film-like laminate comprising at least a substrate layer, an adhesive layer, a barrier layer, and a heat-fusible resin layer in this order;
A step of molding the laminate so as to protrude from the heat-fusible resin layer side to the base layer side, and forming a recess in which an electricity storage device element is housed on the heat-fusible resin layer side. and
A method for producing an exterior material for an electric storage device, wherein the adhesive layer has a porosity of 25% or less in a cross-section in the thickness direction, as observed at a magnification of 150 times with an objective lens.
An electricity storage device in which an electricity storage device element including at least a positive electrode, a negative electrode, and an electrolyte is housed in a package formed using an electricity storage device exterior material,
The exterior material for an electricity storage device is formed of a film-like laminate that includes at least a base layer, an adhesive layer, a barrier layer, and a heat-fusible resin layer in this order,
The power storage device exterior material is molded so as to protrude from the heat-fusible resin layer side to the base layer side, and has a recessed portion in which the power storage device element is accommodated on the heat-fusible resin layer side. and
The power storage device, wherein the adhesive layer has a porosity of 25% or less in a cross section in the thickness direction, as observed at a magnification of 150 times with an objective lens.
An electricity storage comprising a step of housing an electricity storage device element comprising at least a positive electrode, a negative electrode, and an electrolyte in a package formed using the electricity storage device exterior material according to any one of claims 1 to 6. How the device is manufactured.