CN115066792A

CN115066792A - Outer packaging material for electricity storage device, method for producing same, and electricity storage device

Info

Publication number: CN115066792A
Application number: CN202180013374.5A
Authority: CN
Inventors: 天野真; 横田一彦; 山下孝典
Original assignee: Dai Nippon Printing Co Ltd
Current assignee: Dai Nippon Printing Co Ltd
Priority date: 2020-02-05
Filing date: 2021-02-04
Publication date: 2022-09-16
Also published as: JPWO2021157673A1; WO2021157673A1

Abstract

The present invention provides an outer packaging material for an electricity storage device, which can suppress curling due to molding and has high mechanical strength even when the thickness is as thin as 100 [ mu ] m or less. The outer packaging material for an electricity storage device of the present invention is composed of a laminate comprising at least a base material layer, a barrier layer and a heat-sealable resin layer in this order, wherein the thickness of the base material layer is 18 μm to 22 μm, the thickness of the barrier layer is 27 μm to 38 μm, and the thickness of the laminate is 100 μm.

Description

Outer packaging material for electricity storage device, method for producing same, and electricity storage device

Technical Field

The present invention relates to an outer covering material for an electricity storage device, a method for manufacturing the same, and an electricity storage device.

Background

Various types of electricity storage devices have been developed, and in all of the electricity storage devices, a packaging material (outer packaging material) is an indispensable component for packaging electricity storage device elements such as electrodes and electrolytes. Conventionally, as an outer covering material for an electric storage device, a metal outer covering material has been often used.

On the other hand, in recent years, with the increase in performance of electric vehicles, hybrid electric vehicles, personal computers, cameras, cellular phones, and the like, electric storage devices are required to have not only various shapes but also a reduction in thickness and weight. However, the metal outer packaging materials for electric storage devices, which are currently used in many cases, have disadvantages that it is difficult to cope with the diversification of shapes and that weight reduction is also limited.

In recent years, as an outer covering material for an electric storage device which can be easily processed into various shapes and can be made thinner and lighter, a film-like outer covering material in which a base material, an aluminum foil layer, and a heat-fusible resin layer are sequentially laminated has been proposed (for example, see patent document 1).

In such a film-like exterior material, a concave portion is formed by cold forming, and an electric storage device element such as an electrode and an electrolytic solution is disposed in a space formed by the concave portion, and the heat-fusible resin layers are heat-fused to each other, whereby an electric storage device in which the electric storage device element is housed inside the exterior material is obtained.

Documents of the prior art

Patent literature

Patent document 1: japanese unexamined patent publication No. 2008-287971

Disclosure of Invention

Technical problem to be solved by the invention

In recent years, further thinning of film-like outer packaging materials has been demanded. In addition, from the viewpoint of further improving the energy density of the electric storage device, it is necessary to form a deeper concave portion in the outer cover.

On the other hand, the inventors of the present invention have found, after studies, that when a concave portion for housing an electric storage device element is formed by laminating a base layer, a barrier layer, and a heat-fusible resin layer in this order to form an outer casing for an electric storage device, if the thickness of the outer casing for an electric storage device is reduced to 100 μm or less, the edge portion of the concave portion is curled (bent) by molding, which hinders housing of the electric storage device element and heat-fusing of the heat-fusible resin layer, and may cause a reduction in production efficiency of the electric storage device.

In particular, in the case of an electric storage device used for small-sized devices such as personal computers, cameras, and cellular phones, a concave portion having a small area and a large depth is required to be formed in a thin outer covering material, and curling due to molding becomes more remarkable.

Further, when the thickness of the outer packaging material for the electricity storage device is as thin as 100 μm or less, the mechanical strength is reduced, and for example, when the electricity storage device receives an impact from the outside (for example, when the electricity storage device falls), there is a risk that the electricity storage device elements cannot be sufficiently protected.

Under the circumstances, a main object of the present invention is to provide an outer packaging material for an electric storage device, which is capable of suppressing curling due to molding and has high mechanical strength, even when the thickness is as thin as 100 μm or less.

Means for solving the problems

In order to solve the above problems, the present inventors have made intensive studies on suppression of formation curl and improvement of mechanical strength of an outer covering for an electric storage device, which is designed to have a thickness of 100 μm or less, focusing on a laminated structure of the outer covering for an electric storage device. As a result, they have found that an outer casing for an electric storage device having a high mechanical strength can be provided while suppressing formation curling as compared with conventional outer casings for electric storage devices. Specifically, when the total thickness of the laminate constituting the outer packaging material for an electricity storage device is set to 100 μm or less, the outer packaging material for an electricity storage device having a small thickness, suppressed curling due to molding, and high mechanical strength can be obtained by setting the thickness of the base material layer to a range of 18 μm to 22 μm and less, and the thickness of the barrier layer to a range of 27 μm to 38 μm.

The present invention has been completed based on the above-mentioned knowledge and further studies. That is, the present invention provides the following embodiments.

An outer packaging material for an electricity storage device, comprising a laminate having at least a base material layer, a barrier layer and a heat-sealable resin layer in this order, wherein the base material layer has a thickness of 18 μm to 22 μm, the barrier layer has a thickness of 27 μm to 38 μm, and the laminate has a thickness of 100 μm.

Effects of the invention

According to the present invention, it is possible to provide an outer packaging material for an electric storage device, which can suppress curling due to molding and has high mechanical strength, even when the thickness is as thin as 100 μm or less. Further, according to the present invention, a method for manufacturing an outer cover for an electric storage device and an electric storage device can be provided.

Drawings

Fig. 1 is a schematic diagram showing an example of a cross-sectional structure of an outer packaging material for an electric storage device according to the present invention.

Fig. 2 is a schematic diagram showing an example of a cross-sectional structure of an outer packaging material for an electric storage device according to the present invention.

Fig. 3 is a schematic diagram showing an example of a cross-sectional structure of an outer packaging material for an electric storage device according to the present invention.

Fig. 4 is a schematic diagram showing an example of a cross-sectional structure of an outer packaging material for an electric storage device according to the present invention.

Fig. 5 is a schematic diagram for explaining a method of housing electric storage device elements in a package formed of an outer packaging material for electric storage devices of the present invention.

Fig. 6 is a schematic diagram for explaining a method of evaluating curling due to molding of an outer cover for an electricity storage device.

Fig. 7 is a schematic diagram for explaining a method of evaluating curling due to molding of the outer packaging material for an electricity storage device.

Detailed Description

The outer packaging material for an electricity storage device is characterized by being composed of a laminate having at least a base material layer, a barrier layer and a heat-sealable resin layer in this order, the base material layer having a thickness of 18 [ mu ] m or more and 22 [ mu ] m or less, the barrier layer having a thickness of 27 [ mu ] m or more and 38 [ mu ] m or less, and the laminate having a thickness of 100 [ mu ] m or less. The outer packaging material for an electric storage device of the present invention has the above-described structure, and therefore can suppress curling due to molding and has high mechanical strength even when the thickness is as thin as 100 μm or less.

The exterior material for an electricity storage device of the present invention will be specifically described below. In the present specification, the numerical range represented by "to" means "above" and "below". For example, the expression 2 to 15mm means 2mm to 15 mm. In the present specification, the thickness of each layer constituting the laminate is a value obtained by rounding off the first decimal place.

1. Laminated structure and physical properties of outer packaging material for electricity storage device

The outer cover 10 for an electric storage device of the present invention is, for example, a laminate having a base material layer 1, a barrier layer 3, and a heat-fusible resin layer 4 in this order, as shown in fig. 1. In the outer package 10 for an electricity storage device, the base material layer 1 is the outermost layer side, and the heat-fusible resin layer 4 is the innermost layer side. When the electric storage device is assembled using the electric storage device exterior material 10 and the electric storage device element, the electric storage device element is housed in a space formed by heat welding the edge portions in a state where the heat-weldable resin layers 4 of the electric storage device exterior material 10 face each other. In the laminate constituting the outer covering 10 for an electricity storage device of the present invention, the heat-fusible resin layer 4 side is located inside the barrier layer 3 and the base material layer 1 side is located outside the barrier layer 3 with respect to the barrier layer 3.

As shown in fig. 2 to 4, for example, the outer cover 10 for an electricity storage device may be provided with an adhesive layer 2 between the base layer 1 and the barrier layer 3 as needed for the purpose of improving the adhesiveness between the two layers. Further, as shown in fig. 3 and 4, for example, an adhesive layer 5 may be provided between the barrier layer 3 and the heat-fusible resin layer 4 as needed for the purpose of improving the adhesiveness between the two layers. As shown in fig. 4, a surface coating layer 6 or the like may be provided on the outer side of the base material layer 1 (the side opposite to the heat-fusible resin layer 4 side), as required. Specific examples of the laminated structure of the outer cover 10 for an electricity storage device include: a laminated structure formed by sequentially laminating a substrate layer 1, a barrier layer 3 and a heat-fusible resin layer 4; a laminated structure in which a base material layer 1, an adhesive layer 2, a barrier layer 3, and a heat-fusible resin layer 4 are laminated in this order; a laminated structure formed by sequentially laminating a base material layer 1, a barrier layer 3, an adhesive layer 5 and a heat-fusible resin layer 4; a laminated structure in which a base material layer 1, an adhesive layer 2, a barrier layer 3, an adhesive layer 5, and a heat-fusible resin layer 4 are laminated in this order; a laminated structure formed by sequentially laminating a surface covering layer 6, a base material layer 1, a barrier layer 3 and a heat-fusible resin layer 4; a laminated structure in which a surface covering layer 6, a base material layer 1, an adhesive layer 2, a barrier layer 3, and a heat-fusible resin layer 4 are laminated in this order; a laminated structure formed by sequentially laminating a surface covering layer 6, a base material layer 1, a barrier layer 3, an adhesive layer 5 and a heat-fusible resin layer 4; a laminate structure comprising the surface covering layer 6, the base material layer 1, the adhesive layer 2, the barrier layer 3, the adhesive layer 5 and the heat-fusible resin layer 4 laminated in this order. In the laminate structure in which the base material layer 1 is the outermost layer, the lubricant may be present on at least one of the outer side of the base material layer 1 and the inner side of the heat-fusible resin layer 4. In the laminate structure in which the surface-covering layer 6 is the outermost layer, a lubricant may be present on at least one of the outer surface of the surface-covering layer 6 and the inner surface of the heat-fusible resin layer 4. As for the lubricant, it will be explained later.

The thickness of the laminate constituting the outer packaging material for an electric storage device of the present invention is set to 100 μm or less. In the outer packaging material for an electricity storage device of the present invention, by setting the thickness of the laminate to 100 μm or less and setting the thickness of the base material layer 1 and the barrier layer 3, which will be described later, to be within a specific range, curling due to molding can be suppressed even though the thickness of the outer packaging material for an electricity storage device is small, and the outer packaging material for an electricity storage device has high mechanical strength. From the viewpoint of making the thickness of the outer covering material for an electric storage device as thin as possible, suitably suppressing curling due to molding, and suitably exerting high mechanical strength, the thickness of the laminate is preferably about 75 μm or more, more preferably about 77 μm or more, still more preferably about 80 μm or more, still more preferably about 85 μm or more, and still more preferably about 88 μm or more. From the same viewpoint, the thickness of the laminate is preferably about 98 μm or less, more preferably about 95 μm or less, still more preferably about 93 μm or less, and still more preferably about 91 μm or less. Preferable ranges of the thickness of the laminate include about 75 to 100 μm, about 75 to 98 μm, about 75 to 95 μm, about 75 to 93 μm, about 75 to 91 μm, about 77 to 100 μm, about 77 to 98 μm, about 77 to 95 μm, about 77 to 93 μm, about 77 to 91 μm, about 80 to 100 μm, about 80 to 98 μm, about 80 to 95 μm, about 80 to 93 μm, about 80 to 91 μm, about 85 to 100 μm, about 85 to 98 μm, about 85 to 95 μm, about 85 to 93 μm, about 85 to 91 μm, about 88 to 100 μm, about 88 to 98 μm, about 88 to 95 μm, about 88 to 93 μm, and about 88 to 91 μm.

In the outer covering material for an electricity storage device of the present invention, the ratio of the total thickness of the base material layer 1, the adhesive layer 2 provided as needed, the barrier layer 3, the adhesive layer 5 provided as needed, the heat-fusible resin layer 4, and the surface covering layer 6 provided as needed to the thickness (total thickness) of the laminate constituting the outer covering material for an electricity storage device is preferably 90% or more, more preferably 95% or more, and still more preferably 98% or more. Specifically, when the outer cover for an electricity storage device of the present invention 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 ratio of the total thickness of these layers to the thickness (total thickness) of the laminate constituting the outer cover 10 for an electricity storage device is preferably 90% or more, more preferably 95% or more, and still more preferably 98% or more. When the outer cover for an electricity storage device of the present invention includes the base layer 1, the adhesive layer 2, the barrier layer 3, and the heat-fusible resin layer 4, the ratio of the total thickness of these layers to the thickness (total thickness) of the laminate constituting the outer cover 10 for an electricity storage device is also preferably 90% or more, more preferably 95% or more, and still more preferably 98% or more.

In the outer covering material for an electric storage device of the present invention, the total thickness of the layers located on the inner side (the heat-fusible resin layer 4 side) of the barrier layer 3 is preferably about 20 μm or more, more preferably about 22 μm or more, still more preferably about 24 μm or more, and still more preferably about 28 μm or more. The total thickness is preferably about 40 μm or less, more preferably about 38 μm or less, and still more preferably about 35 μm or less. Preferable ranges of the total thickness include about 20 to 40 μm, about 20 to 38 μm, about 20 to 35 μm, about 22 to 40 μm, about 22 to 38 μm, about 22 to 35 μm, about 24 to 40 μm, about 24 to 38 μm, about 24 to 35 μm, about 28 to 40 μm, about 28 to 38 μm, and about 28 to 35 μm.

The thickness of each layer of the exterior material for an electric storage device of the present invention and the thickness of the laminate can be measured by cutting the exterior material for an electric storage device in the thickness direction using, for example, a microtome (micro) manufactured by Daihu optical mechanical Co., Ltd.: REM-710 rettome), dividing the exterior material for an electric storage device into two parts, and observing the obtained cross section with, for example, a laser microscope (VK-9700 manufactured by keyence).

In the outer package for an electric storage device, MD (Machine Direction) and TD (Transverse Direction) of the barrier layer 3, which will be described later, can be generally determined during the production process. For example, when the barrier layer 3 is made of an aluminum foil, so-called linear streaks called Rolling marks are formed on the surface of the aluminum foil in the Rolling Direction (RD: Rolling Direction) of the aluminum foil. Since the rolling mark extends in the rolling direction, the rolling direction of the aluminum foil can be known by observing the surface of the aluminum foil. In addition, in the production process of the laminate, the MD of the laminate is usually matched with the RD of the aluminum foil, and therefore, the MD of the laminate can be determined by observing the surface of the aluminum foil of the laminate and determining the Rolling Direction (RD) of the aluminum foil. Further, since the TD of the laminate is a direction perpendicular to the MD of the laminate, the TD of the laminate can also be determined.

The puncture strength on the outer surface side (base material layer side or surface coating layer side) of the laminate constituting the outer packaging material for an electricity storage device is preferably 19N or more, and more preferably 23N or more. The puncture strength is, for example, 30N or less. The puncture strength can be adjusted by, for example, the lamination structure of the outer packaging material for an electricity storage device, the thickness of the base material layer 1, the draw ratio at the time of manufacturing the base material layer 1, the heat setting temperature, and the like. The puncture strength was measured as follows.

< puncture Strength >

According to JIS Z1707: 1997, the strength of the penetration from the outer surface side (base layer side or surface coating layer side) of the laminate constituting the outer packaging material for an electricity storage device was measured. Examples of the measuring apparatus include ZP-50N (dynamometer) manufactured by IMADA and MX2-500N (measurement stand) manufactured by IMADA. In a measuring environment at 23 + -2 deg.C and a relative humidity of 50 + -5%, a test piece was fixed by a stage having a diameter of 115mm and a pressing plate and having an opening portion having a diameter of 15mm at the center, and a semicircular needle having a diameter of 1.0mm and a tip shape radius of 0.5mm was pierced at a rate of 50 + -5 mm per minute to measure the maximum stress until the needle tip was pierced. The number of test pieces was 10, and the average value was obtained. When the number of test pieces is insufficient and 10 cannot be measured, the measurable number is measured, and the average value is obtained. When the puncture strength is 19N or more, the mechanical strength can be said to be sufficiently high; when 23N or more, the mechanical strength is particularly high.

The dynamic friction coefficient of the outer surface (the surface on the base material layer side or the surface coating layer side) of the outer cover for an electricity storage device is preferably about 0.01 or more, more preferably about 0.05 or more, and even more preferably about 0.09 or more. The coefficient of dynamic friction is preferably about 0.80 or less, more preferably about 0.50 or less, and still more preferably about 0.25 or less. Preferable ranges of the coefficient of dynamic friction include about 0.01 to 0.80, about 0.01 to 0.50, about 0.01 to 0.25, about 0.05 to 0.80, about 0.05 to 0.50, about 0.05 to 0.25, about 0.09 to 0.80, about 0.09 to 0.50, and about 0.09 to 0.25. The dynamic friction coefficient is adjusted by the material of the layer constituting the outer surface of the outer covering material for an electricity storage device, a lubricant, and the like. The dynamic friction coefficient was measured as follows.

< coefficient of dynamic Friction >

According to JIS K7125: 1999 8.1, determine the coefficient of dynamic friction. The outer packaging material for an electricity storage device was cut into two pieces of samples 80mm in the TD direction and 200mm in the MD direction. The samples were then stacked with the outer surfaces facing each other, and a slide was placed thereon. Rubber is adhered to the bottom surface of the sliding sheet, so that the total mass of the sliding sheet is 200g, and the sample is tightly attached to the sliding sheet so as to avoid slipping. Then, the slide piece was pulled at a speed of 100 mm/min, the sliding friction force (N) between the two samples was measured, and the sliding friction force was divided by the normal force (1.96N) of the slide piece to calculate the coefficient of kinetic friction. The coefficient of kinetic friction is determined from the average value of the first 30mm after the relative displacement motion between the contact surfaces is started, ignoring the peak value of the static friction force. And, the load cell is directly connected to the slider.

In the case of performing the following 4-fold test, the number of times until the center portion forms the pinhole is preferably 5 or more, and more preferably 7 or more. When the number of times is 5 or more, it can be said that the mechanical strength of the outer packaging material for an electricity storage device is sufficiently high; when the number is 7 or more, it can be said that the mechanical strength of the outer packaging material for an electric storage device is particularly high.

<4 fold test >

The outer packaging material for an electricity storage device was cut into a strip-shaped piece of TD150mm × MD90mm, which was used as a test sample. The test sample was folded into 4 folds 10 times, and the number of times until a pinhole was formed in the center portion was measured. The operation of folding 4 folds is performed by folding the center positions of the heat-fusible resin layers in the TD direction so that the short sides (the sides in the MD direction) of the test sample overlap each other, folding the center positions in two, folding the center positions of the test sample in 4 folds so that the sides in the TD direction overlap each other in the MD direction, and folding the center positions of the test sample in 4 folds. The test sample was folded and unfolded at 4 folds, and the same operation of folding and unfolding the test sample was repeated to perform the test. The number of test samples was 5, and the number of pinholes formed in the center portion was averaged. When the number of test samples is insufficient and 5 cannot be measured, the measurable number is measured and the average value is obtained.

2. Layers forming an outer packaging material for an electricity storage device

[ base Material layer 1]

In the present invention, the base layer 1 is a layer provided for the purpose of exhibiting a function as a base material of an outer casing for an electricity storage device, and the like. The base material layer 1 is positioned on the outer layer side of the outer packaging material for an electricity storage device. The base material layer 1 may be an outermost layer (a layer constituting an outer surface), and when a surface-covering layer 6 described later is provided, for example, the surface-covering layer 6 may be an outermost layer (a layer constituting an outer surface).

One of the features of the outer packaging material for electricity storage devices of the present invention is that the thickness of the base material layer 1 is set within a specific range of 18 to 22 μm. The thickness of the base material layer 1 is preferably about 19 μm or more from the viewpoint that although the thickness of the outer packaging material for an electricity storage device is small, curling due to molding can be appropriately suppressed, and high mechanical strength is appropriately exhibited. From the same viewpoint, the thickness of the base material layer 1 is preferably about 21 μm or less. Preferable ranges of the thickness of the base material layer 1 include about 18 to 21 μm, about 19 to 22 μm, and about 19 to 21 μm. However, in the present invention, when the base material layer 1 is composed of two or more layers and these layers are bonded to each other with a layer of an adhesive such as an adhesive layer, the total thickness of the base material layer 1 does not include the thickness of the layer of the adhesive.

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

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

Examples of the resin forming the base layer 1 include resins such as polyester, polyamide, polyolefin, epoxy resin, acrylic resin, fluororesin, polyurethane, silicone resin, and phenol resin, and modified products of these resins. The resin forming the base layer 1 may be a copolymer of these resins, or may be a modified product of the copolymer. Mixtures of these resins are also possible.

As the resin forming the base layer 1, polyester and polyamide are preferably used.

Specific examples of the polyester include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolyester. The copolyester mainly composed of ethylene terephthalate may be mentioned. Specific examples thereof include a copolyester composed mainly of ethylene terephthalate as a repeating unit and polymerized with ethylene isophthalate (hereinafter, abbreviated as poly (terephthalic acid/isophthalic acid) ethylene glycol), poly (terephthalic acid/adipic acid) ethylene glycol, poly (sodium terephthalate/isophthalate) ethylene glycol, poly (terephthalic acid/benzenedicarboxylic acid) ethylene glycol, and poly (terephthalic acid/sebacic acid) ethylene glycol. These polyesters may be used alone in 1 kind, or may be used in combination of 2 or more kinds.

Further, as the polyamide, specifically, there can be mentioned: aliphatic polyamides such as nylon 6, nylon 66, nylon 610, nylon 12, nylon 46, and copolymers of nylon 6 and nylon 66; aromatic-containing polyamides such as hexamethylenediamine-isophthalic acid-terephthalic acid copolyamides including nylon 6I, nylon 6T, nylon 6IT, and nylon 6I6T (I represents isophthalic acid and T represents terephthalic acid) containing a structural unit derived from terephthalic acid and/or isophthalic acid, and polyamides MXD6 (poly-m-xylylene adipamide); alicyclic polyamides such as polyamide PACM6 (poly (4-aminocyclohexyl) methane adipamide); and polyamides obtained by copolymerizing with an isocyanate component such as a lactone component or 4,4' -diphenylmethane-diisocyanate; a polyester amide copolymer or a polyether ester amide copolymer as a copolymer of a copolyamide and a polyester or polyalkylene ether glycol; and polyamides such as copolymers of the above compounds. These polyamides may be used alone in 1 kind, or may be used in combination of 2 or more kinds.

The base material layer 1 preferably includes at least one of a polyester film, a polyamide film, and a polyolefin film, preferably at least one of a stretched polyester film, a stretched polyamide film, and a stretched polyolefin film, more preferably at least one of a stretched polyethylene terephthalate film, a stretched polybutylene terephthalate film, a stretched nylon film, and a stretched polypropylene film, and still more preferably at least one of a biaxially stretched polyethylene terephthalate film, a biaxially stretched polybutylene terephthalate film, a biaxially stretched nylon film, and a biaxially stretched polypropylene film.

The substrate layer 1 may be a single layer, or may be composed of 2 or more layers. When the base material layer 1 is composed of 2 or more layers, the base material layer 1 may be a laminate in which resin films are laminated with an adhesive or the like, or may be a laminate in which resin films of 2 or more layers are formed by coextrusion. The laminate of the resin film formed by coextruding the resin into 2 or more layers may be used as the base layer 1 as it is without stretching, or may be uniaxially or biaxially stretched to form the base layer 1.

Specific examples of the laminate of 2 or more resin films in the base layer 1 include a laminate of a polyester film and a nylon film, a laminate of 2 or more nylon films, and a laminate of 2 or more polyester films, and preferably a laminate of a stretched nylon film and a stretched polyester film, a laminate of 2 or more stretched nylon films, and a laminate of 2 or more stretched polyester films. For example, when the base layer 1 is a laminate of 2 resin films, it is preferably a laminate of a polyester resin film and a polyester resin film, a laminate of a polyamide film and a polyamide film, or a laminate of a polyester resin film and a polyamide film, and more preferably a laminate of a polyethylene terephthalate film and a polyethylene terephthalate film, a laminate of a nylon film and a nylon film, or a laminate of a polyethylene terephthalate film and a nylon film. Further, since the polyester resin is less likely to be discolored when, for example, an electrolyte solution is adhered to the surface thereof, it is preferable that the polyester resin film is located on the outermost layer of the base material layer 1 when the base material layer 1 is a laminate of 2 or more resin films.

When the base material layer 1 is a laminate of 2 or more resin films, the 2 or more resin films may be laminated by an adhesive. Preferable examples of the adhesive include the same adhesives as those exemplified for the adhesive layer 2 described below. The method for laminating the 2-or more-layer resin film is not particularly limited, and known methods can be used, and examples thereof include a dry lamination method, a sandwich lamination method, an extrusion lamination method, a thermal lamination method, and the like, and a dry lamination method is preferable. When lamination is performed by a dry lamination method, a urethane adhesive is preferably used as the adhesive. In this case, the thickness of the adhesive is, for example, about 2 to 5 μm. Further, an Anchor coat layer (Anchor coat layer) may be formed on the resin film and laminated. The anchor coat layer may be made of the same material as the adhesive exemplified in the adhesive layer 2 described below. In this case, the thickness of the anchor coat layer is, for example, about 0.01 to 1.0 μm. The thickness of the anchor coat layer is not included in the thickness of the base material layer 1.

The base layer 1 is preferably formed of a single-layer nylon film in order to suitably suppress curling due to molding and suitably exhibit high mechanical strength even when the thickness of the outer packaging material for an electricity storage device is small.

When the substrate layer 1 comprises a polyamide film, the polyamide film preferably has a crystallinity index of 1.50 or more as measured from the outside of the substrate layer 1 by the ATR method of fourier transform infrared spectroscopy. The method for measuring the crystal index of the base layer 1 of the outer packaging material 10 for an electricity storage device of the present invention is as follows.

< measurement of Crystal index of base Material layer of outer Material for Power storage device >

Cutting outer packaging material for electricity storage device into pieces of 100mm × 100mmSquare, sample is made. The infrared absorption spectrum of the surface of the polyamide film located on the outer side of the obtained sample was measured in an FT-IR ATR measurement mode at a temperature of 25 ℃ and a relative humidity of 50%. As the apparatus, for example, Nicolet iS10 manufactured by Thermo Fisher Scientific Co. From the obtained absorption spectrum, 1200cm of absorption of alpha crystal derived from nylon was measured ^-1 Nearby peak intensity P and 1370cm from absorption not related to crystallization ^-1 The intensity ratio X of the peak intensity P to the peak intensity Q was calculated as P/Q as the crystal index. When the outer package for an electricity storage device was obtained from an electricity storage device and the crystal index of the base layer was measured, samples were prepared by obtaining the outer package for an electricity storage device from the top surface or the bottom surface, not from the heat-welded portions or the side surfaces of the electricity storage device.

(measurement conditions)

The method comprises the following steps: micro ATR method

Wave number resolution: 8cm ^-1

And (4) accumulating times: 32 times (twice)

A detector: DTGS detector

ATR prism: ge (germanium) oxide

Incident angle: 45 degree

Baseline: at wave number 1100cm ^-1 ～1400cm ^-1 The values are found by linear approximation.

Absorption peak intensity Y ₁₂₀₀ : wave number 1195cm ^-1 ～1205cm ^-1 The maximum value of the peak intensity within the range of (1) minus the difference of the baseline value

Absorption peak intensity Y ₁₃₇₀ : wave number 1365cm ^-1 ～1375cm ^-1 The maximum value of the peak intensity within the range of (1) minus the difference of the baseline value

When the outer surface of the outer package 10 for an electricity storage device is formed of the polyamide film of the base material layer 1, the outer package 10 for an electricity storage device may be directly used as a measurement target of the crystal index. In the case where the base material layer 1 has a multilayer structure as described above and a resin film (for example, polyester film) other than the polyamide film is located outside the polyamide film, or in the case where the outer surface of the electric storage device outer package 10, such as the surface covering layer 6 described later, is laminated outside the base material layer 1 and is not composed of the polyamide film of the base material layer 1, the layer located outside the polyamide film may be removed from the electric storage device outer package 10 and the crystal index may be measured in a state where the surface of the polyamide film is exposed.

In the outer sheath material 10 for an electric storage device, the above-mentioned crystal index may be 1.50 or more, but from the viewpoint that curling due to molding can be appropriately suppressed and high mechanical strength can be appropriately exerted even though the thickness of the outer sheath material for an electric storage device is thin, it is more preferably 1.55 or more, still more preferably 1.60 or more, still more preferably 1.65 or more, and particularly preferably 1.69 or more. The upper limit of the above-mentioned crystal index is not particularly limited, and examples thereof include 2.50 or less and 1.80 or less. Preferable ranges of the crystal index include, for example, 1.50 to 2.50, 1.60 to 2.50, 1.65 to 2.50, 1.69 to 2.50, 1.50 to 1.80, 1.60 to 1.80, 1.65 to 1.80, 1.69 to 1.80, and the like.

As a method for increasing the crystal index of the polyamide film included in the base layer 1 of the outer packaging material for an electricity storage device 10 to 1.50 or more, there is a method for promoting crystallization (promoting the formation of α crystals) by the draw ratio, the heat fixation temperature, the temperature and time of post-heating in the production process of the polyamide film, and the like.

Further, additives such as a lubricant, a flame retardant, an antiblocking agent, an antioxidant, a light stabilizer, a thickener, and an antistatic agent may be present on at least one of the surface and the inside of the base layer 1. The additive may be used in a single amount of 1 kind, or may be used in combination of 2 or more kinds.

In the present invention, a lubricant is preferably present on the surface of the base material layer 1 from the viewpoint of improving the formability of the outer packaging material for an electricity storage device. The lubricant is not particularly limited, but preferably includes an amide-based lubricant. Specific examples of the amide-based lubricant include saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, methylol amides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, fatty acid ester amides, and aromatic bisamides. Specific examples of the saturated fatty amide include lauramide, palmitamide, stearamide, behenamide, and hydroxystearamide. Specific examples of the unsaturated fatty amide include oleamide and erucamide. Specific examples of the substituted amide include N-oleyl palmitamide, N-stearyl stearamide, N-stearyl oleamide, N-oleyl stearamide, N-stearyl erucamide and the like. Specific examples of the methylolamide include methylolstearylamide. Specific examples of the saturated fatty acid bisamide include methylene bisstearamide, ethylene biscapramide, ethylene bislauramide, ethylene bisstearamide, ethylene bishydroxystearamide, ethylene bisbehenamide, hexamethylene bisstearamide, hexamethylene bisbehenamide, hexamethylene hydroxystearamide, N '-distearyldiadipamide, N' -distearyldisebacamide, and the like. Specific examples of the unsaturated fatty acid bisamide include ethylene bisoleamide, ethylene biserucamide, hexamethylene bisoleamide, N '-dioleyl adipamide, N' -dioleyl sebacamide, and the like. Specific examples of the fatty acid ester amide include stearic amide ethyl stearate. Specific examples of the aromatic bisamide include m-xylene bisstearamide, m-xylene bishydroxystearamide, and N, N' -distearyl isophthalamide. The number of the lubricants may be 1 or more.

When the lubricant is present on the surface of the base material layer 1, the amount thereof is not particularly limited, but is preferably about 3mg/m ² More preferably 4 to 15mg/m ² About, more preferably 5 to 14mg/m ² Left and right.

The lubricant present on the surface of the base material layer 1 may be a lubricant exuded from a resin constituting the base material layer 1, or may be a lubricant applied to the surface of the base material layer 1. The lubricant present on the surface of the base material layer 1 may be transferred to the surface of the base material layer 1 in a state where the outer packaging material for an electric storage device is in a wound body wound around a winding core or the like.

[ adhesive layer 2]

In the outer packaging material for an electricity storage device of the present invention, the adhesive layer 2 is provided between the base material layer 1 and the barrier layer 3 as necessary for the purpose of improving the adhesiveness therebetween.

The adhesive layer 2 is formed of an adhesive capable of bonding the base layer 1 and the barrier layer 3. The adhesive used to form the adhesive layer 2 is not limited, and may be any of a chemical reaction type, a solvent volatilization type, a hot melt type, a hot press type, and the like. The adhesive may be a two-component curing adhesive (two-component adhesive), a one-component curing adhesive (one-component adhesive), or a resin that does not involve a curing reaction. The adhesive layer 2 may be a single layer or a plurality of layers.

Specific examples of the adhesive component contained in the adhesive include: polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolyester; a polyether; a polyurethane; an epoxy resin; a phenolic resin; polyamides such as nylon 6, nylon 66, nylon 12, and copolyamide; polyolefin resins such as polyolefin, cyclic polyolefin, acid-modified polyolefin, and acid-modified cyclic polyolefin; polyvinyl acetate; cellulose; (meth) acrylic resins; a polyimide; a polycarbonate; amino resins such as urea resins and melamine resins; rubbers such as chloroprene rubber, nitrile rubber, and styrene-butadiene rubber; silicone resins, and the like. These adhesive components may be used alone in 1 kind, or may be used in combination in 2 or more kinds. Among these adhesive components, a polyurethane adhesive is preferably used. In addition, the resin forming these adhesive components may be used in combination with an appropriate curing agent to improve the adhesive strength. The curing agent may be appropriately selected from polyisocyanates, polyfunctional epoxy resins, oxazoline group-containing polymers, polyamine resins, acid anhydrides, and the like, depending on the functional group of the adhesive component.

The urethane adhesive includes, for example, a main agent containing a polyol compound and a curing agent containing an isocyanate compound. Preferred examples of the adhesive include a two-pack type curable polyurethane adhesive comprising a polyol such as a polyester polyol, a polyether polyol and an acrylic polyol as a main component and an aromatic or aliphatic polyisocyanate as a curing agent. In addition, as the polyol compound, a polyester polyol having a hydroxyl group in a side chain in addition to a hydroxyl group at the terminal of the repeating unit is preferably used. Examples of the curing agent include aliphatic, alicyclic, aromatic, and araliphatic isocyanate compounds. Examples of the isocyanate compound include Hexamethylene Diisocyanate (HDI), Xylylene Diisocyanate (XDI), isophorone diisocyanate (IPDI), hydrogenated XDI (H6XDI), hydrogenated MDI (H12MDI), Toluene Diisocyanate (TDI), diphenylmethane diisocyanate (MDI), and Naphthalene Diisocyanate (NDI). Further, 1 or 2 or more kinds of modified polyfunctional isocyanates derived from these diisocyanates, and the like can be also exemplified. In addition, as the polyisocyanate compound, multimers (e.g., trimers) can also be used. Such polymers include adducts, biurets, and uretates. By forming the adhesive layer 2 from a urethane adhesive, excellent electrolyte resistance can be imparted to the outer packaging material for an electricity storage device, and peeling of the base material layer 1 can be suppressed even if an electrolyte adheres to the side surfaces.

The adhesive layer 2 may contain a colorant, a thermoplastic elastomer, a tackifier, a filler, and the like, as long as the addition of other components is not inhibited. The adhesive layer 2 contains a coloring agent, whereby the outer cover material for an electricity storage device can be colored. As the colorant, known materials such as pigments, dyes, and the like can be used. In addition, only 1 kind of colorant may be used, or 2 or more kinds may be mixed and used.

The type of pigment is not particularly limited as long as the adhesiveness to the adhesive layer 2 is not impaired. Examples of the organic pigment include azo pigments, phthalocyanine pigments, quinacridone pigments, anthraquinone pigments, dioxazine pigments, indigo-thioindigo pigments, perinone pigments, isoindoline pigments, and benzimidazolone pigments; examples of the inorganic pigment include carbon black-based, titanium oxide-based, cadmium-based, lead-based, chromium oxide-based, and iron-based pigments, and fine powders of mica (mica) and fish scale foils.

Among the colorants, carbon black is preferable, for example, in order to make the appearance of the outer packaging material for an electric storage device black.

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

The content of the pigment in the adhesive layer 2 is not particularly limited as long as the outer packaging material for an electricity storage device can be colored, and may be, for example, about 5 to 60 mass%, preferably 10 to 40 mass%.

The thickness of the adhesive layer 2 is not particularly limited as long as the base layer 1 and the barrier layer 3 can be adhered to each other, and is, for example, about 1 μm or more and about 2 μm or more. The thickness of the adhesive layer 2 is, for example, about 10 μm or less and about 5 μm or less. 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.

[ coloring layer ]

The colored layer is a layer (not shown) provided between the base material layer 1 and the barrier layer 3 as necessary. When the adhesive layer 2 is provided, a colored layer may be provided between the base material layer 1 and the adhesive layer 2, or between the adhesive layer 2 and the barrier layer 3. Further, a colored layer may be provided outside the base material layer 1. By providing the coloring layer, the outer packaging material for the electric storage device can be colored.

The colored layer can be formed by, for example, applying an ink containing a colorant to the surface of the base layer 1 or the surface of the barrier layer 3. As the colorant, known colorants such as pigments and dyes can be used. In addition, only 1 kind of colorant may be used, or 2 or more kinds may be mixed and used.

Specific examples of the coloring agent contained in the colored layer include those similar to those listed in the section of the adhesive layer 2.

[ Barrier layer 3]

In the outer packaging material for an electricity storage device, the barrier layer 3 is a layer that at least inhibits moisture penetration.

Examples of the barrier layer 3 include a metal foil having barrier properties, a vapor deposited film, and a resin layer. Examples of the vapor deposited film include a metal vapor deposited film, an inorganic oxide vapor deposited film, and a carbon-containing inorganic oxide vapor deposited film, and examples of the resin layer include a polyvinylidene chloride, a polymer containing Chlorotrifluoroethylene (CTFE) as a main component, a polymer containing Tetrafluoroethylene (TFE) as a main component, a fluorine-containing resin such as a polymer having a fluoroalkyl group, and a polymer containing a fluoroalkyl group unit as a main component, and an ethylene-vinyl alcohol copolymer. The barrier layer 3 may be a resin film provided with at least 1 of the vapor deposited film and the resin layer. The barrier layer 3 may also be provided in a plurality of layers. The barrier layer 3 preferably comprises a layer consisting of a metallic material. Specific examples of the metal material constituting the barrier layer 3 include aluminum alloy, stainless steel, titanium steel, and steel plate, and when used in the form of a metal foil, it is preferable to include at least one of aluminum alloy foil and stainless steel foil.

The aluminum alloy foil is more preferably a soft aluminum alloy foil made of, for example, an aluminum alloy subjected to annealing treatment or the like from the viewpoint of improving the formability of the outer covering material for an electric storage device, and is preferably an iron-containing aluminum alloy foil from the viewpoint of further improving the formability. The iron content in the iron-containing aluminum alloy foil (100 mass%) is preferably 0.1 to 9.0 mass%, more preferably 0.5 to 2.0 mass%. When the iron content is 0.1 mass% or more, an outer packaging material for an electricity storage device having more excellent moldability can be obtained. When the iron content is 9.0 mass% or less, an outer packaging material for an electric storage device having more excellent flexibility can be obtained. Examples of the soft aluminum alloy foil include those having a chemical composition of JIS H4160: 1994A8021H-O, JIS H4160: 1994A8079H-O, JIS H4000: 2014A8021P-O, or JIS H4000: 2014A 8079P-O. Silicon, magnesium, copper, manganese, and the like may be added as necessary. Further, softening can be achieved by annealing or the like.

Examples of the stainless steel foil include austenitic, ferritic, austenitic-ferritic, martensitic, and precipitation hardening stainless steel foils. In addition, the stainless steel foil is preferably made of austenitic stainless steel from the viewpoint of providing an outer covering material for an electric storage device having more excellent moldability.

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

One of the features of the outer packaging material for an electricity storage device of the present invention is that the thickness of the barrier layer 3 is set to a specific range of 27 to 38 μm. From the viewpoint of suitably suppressing curling due to molding and suitably exhibiting high mechanical strength even though the outer packaging material for an electric storage device has a small thickness, the thickness of the barrier layer 3 is preferably 28 μm or more, more preferably about 30 μm or more, and still more preferably 33 μm or more. From the same viewpoint, the thickness of the barrier layer is preferably 37 μm or less, more preferably 36 μm or less. Preferable ranges of the thickness of the barrier layer include about 27 to 37 μm, about 27 to 36 μm, about 28 to 38 μm, about 28 to 37 μm, about 28 to 36 μm, about 30 to 38 μm, about 30 to 37 μm, about 30 to 36 μm, about 33 to 38 μm, about 33 to 37 μm, and about 33 to 36 μm.

When the barrier layer 3 is a metal foil, it is preferable to provide a corrosion-resistant coating film on at least the surface opposite to the base material layer in order to prevent dissolution, corrosion, and the like. The barrier layer 3 may have a corrosion-resistant coating on both surfaces. Here, the corrosion-resistant coating is a thin film having corrosion resistance (for example, acid resistance, alkali resistance, etc.) of the barrier layer by subjecting the surface of the barrier layer to hot water conversion treatment such as boehmite treatment, chemical surface treatment, anodic oxidation treatment, plating treatment of nickel, chromium, etc., and corrosion-resistant treatment by applying a coating material. The corrosion-resistant coating specifically refers to a coating that improves the acid resistance of the barrier layer (acid-resistant coating), a coating that improves the alkali resistance of the barrier layer (alkali-resistant coating), and the like. The treatment for forming the corrosion-resistant coating may be performed in 1 kind, or 2 or more kinds may be combined. Further, not only 1 layer but also a plurality of layers may be formed. Among these treatments, the hot water conversion treatment and the anodic oxidation treatment are treatments in which the surface of the metal foil is dissolved by a treating agent to form a metal compound having excellent corrosion resistance. These treatments are sometimes included in the definition of chemical surface treatment. Further, when the barrier layer 3 has a corrosion-resistant film, the corrosion-resistant film is included as the barrier layer 3.

The corrosion-resistant coating exhibits the following effects when the outer packaging material for an electricity storage device is molded: preventing delamination between the barrier layer (e.g., aluminum alloy foil) and the substrate layer; the surface of the barrier layer is prevented from being dissolved and corroded by hydrogen fluoride generated by the reaction of electrolyte and moisture, and particularly when the barrier layer is an aluminum alloy foil, aluminum oxide on the surface of the barrier layer is prevented from being dissolved and corroded; and improving the adhesion (wettability) of the barrier layer surface; preventing delamination of the substrate layer and the barrier layer upon heat sealing; prevent the base material layer and the barrier layer from delaminating during molding.

Various types of corrosion-resistant films formed by chemical surface treatment are known, and examples thereof include corrosion-resistant films containing at least 1 of phosphate, chromate, fluoride, triazine thiol compounds, and rare earth oxides. Examples of the chemical surface treatment using a phosphate or a chromate include chromate treatment, phosphate chromate treatment, phosphoric acid-chromate treatment, and the like, and examples of the chromium compound used in these treatments include chromium nitrate, chromium fluoride, chromium sulfate, chromium acetate, chromium oxalate, chromium dihydrogen phosphate, chromic acid acetoacetate, chromium chloride, chromium potassium sulfate, and the like. Examples of the phosphorus compound used in these treatments include sodium phosphate, potassium phosphate, ammonium phosphate, and polyphosphoric acid. The chromate treatment includes etching chromate treatment, electrolytic chromate treatment, coating chromate treatment, and the like, and the coating chromate treatment is preferable. The coating type chromate treatment is as follows: first, at least the inner layer side surface of the barrier layer (for example, aluminum alloy foil) is degreased by a known treatment method such as an alkali immersion method, an electrolytic cleaning method, an acid cleaning method, an electrolytic acid cleaning method, or an acid activation method, and then a treatment liquid containing a metal phosphate such as Cr (chromium) phosphate, Ti (titanium) phosphate, Zr (zirconium) phosphate, or Zn (zinc) phosphate and a mixture of these metal salts as main components, a treatment liquid containing a nonmetal phosphate and a mixture of these nonmetal salts as main components, or a treatment liquid containing a mixture of these nonmetal salts and a synthetic resin or the like is applied to the degreased surface by a known application method such as a roll coating method, a gravure printing method, or an immersion method, and dried. For the treatment liquid, various solvents such as water, alcohol solvents, hydrocarbon solvents, ketone solvents, ester solvents, and ether solvents can be used, and water is preferred. Examples of the resin component used in this case include polymers such as phenolic resins and acrylic resins, and chromate treatment using an aminated phenol polymer having a repeating unit represented by the following general formulae (1) to (4). In the aminated phenol polymer, the repeating units represented by the following general formulae (1) to (4) may be contained in 1 kind alone, or may be contained in any combination of 2 or more kinds. The acrylic resin is preferably polyacrylic acid, acrylic acid methacrylate copolymer, acrylic acid maleic acid copolymer, acrylic acid styrene copolymer, or derivatives thereof such as sodium salt, ammonium salt, and amine salt. Particularly preferred are polyacrylic acid derivatives such as ammonium salts, sodium salts, and amine salts of polyacrylic acid. In the present invention, polyacrylic acid refers to a polymer of acrylic acid. The acrylic resin is also preferably a copolymer of acrylic acid and a dicarboxylic acid or dicarboxylic anhydride, and is also preferably an ammonium salt, a sodium salt, or an amine salt of the copolymer of acrylic acid and a dicarboxylic acid or dicarboxylic anhydride. The acrylic resin may be used alone in 1 kind, or 2 or more kinds may be mixed and used.

In the general formulae (1) to (4), X represents a hydrogen atom, a hydroxyl group, an alkyl group, a hydroxyalkyl group, an allyl group or a benzyl group. Furthermore, R ¹ And R ² Each of which is the same or different, represents a hydroxyl group, an alkyl group or a hydroxyalkyl group. X, R in the general formulae (1) to (4) ¹ And R ² Examples of the alkyl group include linear or branched alkyl groups having 1 to 4 carbon atoms such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, and a tert-butyl group. X, R ¹ And R ² Examples of the hydroxyalkyl group include a linear or branched alkyl group having 1 to 4 carbon atoms, such as a hydroxymethyl group, 1-hydroxyethyl group, 2-hydroxyethyl group, 1-hydroxypropyl group, 2-hydroxypropyl group, 3-hydroxypropyl group, 1-hydroxybutyl group, 2-hydroxybutyl group, 3-hydroxybutyl group, or 4-hydroxybutyl group, which is substituted for 1 hydroxyl group. X, R in the general formulae (1) to (4) ¹ And R ² The alkyl and hydroxyalkyl groups shown may be the same or different, respectively. In the general formulae (1) to (4), X is preferably a hydrogen atom, a hydroxyl group or a hydroxyalkyl group. The number average molecular weight of the aminated phenol resin having the repeating units represented by the general formulae (1) to (4) is preferably about 500 to 100 ten thousand, more preferably about 1000 to 2 ten thousand. The aminated phenol-formaldehyde polymer is produced by, for example, polycondensing a phenol compound or naphthol compound with formaldehyde to produce a polymer comprising repeating units represented by the above general formula (1) or general formula (3), and further using formaldehyde and an amine (R) ¹ R ² NH) general functional group (-CH) ₂ NR ¹ R ² ) The polymer obtained above is introduced into the reactor. The aminated phenol formaldehyde polymer can be used alone in 1 kind, or more than 2 kinds can be mixed for use.

As another example of the corrosion-resistant coating, a thin film formed by coating type anticorrosive treatment with a coating material containing at least 1 kind selected from rare earth element oxide sol, anionic polymer, and cationic polymer can be cited. The coating may also contain phosphoric acid or a phosphate salt, a crosslinking agent to crosslink the polymer. In the rare earth element oxide sol, fine particles of a rare earth element oxide (for example, particles having an average particle diameter of 100nm or less) are dispersed in a liquid dispersion medium. Examples of the rare earth element oxide 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 oxide contained in the corrosion-resistant coating may be used alone in 1 kind or in combination with 2 or more kinds. As the liquid dispersion medium of the rare earth element oxide sol, various solvents such as water, alcohol-based solvents, hydrocarbon-based solvents, ketone-based solvents, ester-based solvents, and ether-based solvents can be used, and water is preferred. As the cationic polymer, for example, polyethyleneimine, an ionic polymer complex composed of polyethyleneimine and a polymer having a carboxylic acid, a primary amine-grafted acrylic resin in which a primary amine is graft-polymerized to an acrylic backbone, polyallylamine or a derivative thereof, and an aminated phenol are preferable. The anionic polymer is preferably poly (meth) acrylic acid or a salt thereof, or a copolymer mainly composed of (meth) acrylic acid or a salt thereof. The crosslinking agent is preferably at least 1 selected from compounds having any functional group of an isocyanate group, a glycidyl group, a carboxyl group, and an oxazoline group, and silane coupling agents. The phosphoric acid or phosphate is preferably a condensed phosphoric acid or a condensed phosphate.

Examples of the corrosion-resistant coating include: a coating film formed by applying a dispersion liquid in which fine particles of barium sulfate or a metal oxide such as alumina, titanium oxide, cerium oxide, or tin oxide are dispersed in phosphoric acid to the surface of the barrier layer and baking the coating film at a temperature of 150 ℃ or higher.

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

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

In the chemical surface treatment, the amount of the corrosion-resistant coating formed on the surface of the barrier layer 3 is not particularly limited, and for example, in the case of performing coating-type chromate treatment, it is desirable that the barrier layer 3 is formed every 1m ² On the surface, the content of the chromic acid compound is, for example, about 0.5 to 50mg, preferably about 1.0 to 40mg, in terms of chromium, the content of the phosphorus compound is, for example, about 0.5 to 50mg, preferably about 1.0 to 40mg, in terms of phosphorus, and the content of the aminated phenol polymer is, for example, about 1.0 to 200mg, preferably about 5.0 to 150 mg.

The thickness of the corrosion-resistant coating is not particularly limited, but is preferably about 1nm to 20 μm, more preferably about 1nm to 100nm, and still more preferably about 1nm to 50nm, from the viewpoint of the cohesive force of the coating and the adhesion force with the barrier layer or the heat-fusible resin layer. Wherein the corrosion-resistant coating isThe thickness can be determined by observation with a transmission electron microscope, or a combination of observation with a transmission electron microscope and energy dispersive X-ray spectroscopy or electron beam energy loss spectroscopy. By analyzing the composition of the corrosion-resistant coating by time-of-flight secondary ion mass spectrometry, secondary ions derived from, for example, Ce, P and O (e.g., Ce) ₂ PO ₄ ^﹢ 、CePO ₄ ^﹣ Etc.), for example, a secondary ion (e.g., CrPO) composed of Cr, P, and O ₂ ^﹢ 、CrPO ₄ ^﹣ Etc.).

The chemical surface treatment can be performed by applying a solution containing a compound for forming a corrosion-resistant coating on the surface of the barrier layer by a bar coating method, a roll coating method, a gravure coating method, a dipping method, or the like, and then heating the barrier layer to a temperature of about 70 to 200 ℃. Before the barrier layer is subjected to the chemical surface treatment, the barrier layer may be subjected to a degreasing treatment in advance 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 manner, the surface of the barrier layer can be more efficiently subjected to the chemical surface treatment. Further, by using an acid degreasing agent in which a fluorine-containing compound is dissolved with an inorganic acid in degreasing treatment, not only the degreasing effect of the metal foil can be achieved, but also passive metal fluoride can be formed, and in this case, only degreasing treatment can be performed.

[ Heat-fusible resin layer 4]

In the outer covering material for an electric storage device of the present invention, the heat-fusible resin layer 4 corresponds to the innermost layer, and the heat-fusible resin layers are heat-fused to each other at the time of assembling the electric storage device, and serve as a layer (sealing layer) that seals the electric storage device element.

The resin constituting the heat-fusible resin layer 4 is not particularly limited as long as heat-fusing can be achieved, and a resin having a polyolefin skeleton such as polyolefin and acid-modified polyolefin is preferable. The resin constituting the heat-sealable resin layer 4 can be analyzed by, for example, infrared spectroscopy, gas chromatography mass spectrometry, or the like, since it contains a polyolefin skeleton. In addition, the method can be used for producing a composite materialWhen the resin constituting the heat-fusible resin layer 4 is analyzed by infrared spectroscopy, a peak derived from maleic anhydride is preferably detected. For example, when the maleic anhydride-modified polyolefin is measured by infrared spectroscopy, it is measured at a wavenumber of 1760cm ^-1 Neighborhood and wavenumber 1780cm ^-1 A peak derived from maleic anhydride was detected nearby. When the heat-fusible resin layer 4 was a layer formed of maleic anhydride-modified polyolefin, a peak derived from maleic anhydride was detected when measured by infrared spectroscopy. However, when the degree of acid modification is low, it may not be detected because the peak value is small. In this case, the analysis can be performed by nuclear magnetic resonance spectroscopy.

Specific examples of the polyolefin include polyethylenes such as low density polyethylene, medium density polyethylene, high density polyethylene, and linear low density polyethylene; ethylene-alpha-olefin copolymers; polypropylene such as homopolypropylene, a block copolymer of polypropylene (for example, a block copolymer of propylene and ethylene), a random copolymer of polypropylene (for example, a random copolymer of propylene and ethylene), and the like; propylene- α -olefin copolymers; ethylene-butene-propylene terpolymers, and the like. Among them, polypropylene is preferable. In the case of a copolymer, the polyolefin resin may be a block copolymer or a random copolymer. These polyolefin resins may be used alone in 1 kind, or may be used in combination in 2 or more kinds.

In addition, the polyolefin may also be a cyclic polyolefin. The cyclic polyolefin is a copolymer of an olefin and a cyclic monomer, and examples of the olefin as a structural monomer of the cyclic polyolefin include ethylene, propylene, 4-methyl-1-pentene, styrene, butadiene, isoprene, and the like. Examples of the cyclic monomer as a structural monomer of the cyclic polyolefin include cyclic olefins such as norbornene; cyclic dienes such as cyclopentadiene, dicyclopentadiene, cyclohexadiene and norbornadiene. Among them, cyclic olefins are preferably cited, and norbornene is more preferred.

The acid-modified polyolefin is a polymer modified by block polymerization or graft polymerization of a polyolefin using an acid component. As the acid-modified polyolefin, any of the above-mentioned polyolefins, copolymers obtained by copolymerizing polar molecules such as acrylic acid or methacrylic acid with the above-mentioned polyolefins, and polymers such as crosslinked polyolefins can be used. Examples of the acid component used for acid modification include carboxylic acids such as maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, and itaconic anhydride, and anhydrides thereof.

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

Examples of the preferred acid-modified polyolefin include polyolefins modified with a carboxylic acid or an anhydride thereof, polypropylene modified with a carboxylic acid or an anhydride thereof, maleic anhydride-modified polyolefins, and maleic anhydride-modified polypropylene.

The heat-fusible resin layer 4 may be formed of 1 resin alone or a blend polymer of 2 or more resins in combination. The heat-fusible resin layer 4 may be formed of only 1 layer, or may be formed of 2 or more layers of the same or different resins.

The heat-fusible resin layer 4 may contain a lubricant as needed. When the heat-fusible resin layer 4 contains a lubricant, the moldability of the outer covering material for an electricity storage device can be improved. As the lubricant, there is no particular limitation, and known lubricants can be used. The number of the lubricants may be 1 or more.

The lubricant is not particularly limited, but preferably includes an amide-based lubricant. Specific examples of the lubricant include the lubricant exemplified in the base layer 1. The number of the lubricants may be 1 or more.

When a lubricant is present on the surface of the heat-fusible resin layer 4, the amount of the lubricant is not particularly limited, and is preferably 10 to 50mg/m from the viewpoint of improving the moldability of the outer packaging material for an electricity storage device ² About, more preferably 15 to 40mg/m ² Left and right.

The lubricant present on the surface of the heat-fusible resin layer 4 may be one from which a lubricant contained in the resin constituting the heat-fusible resin layer 4 bleeds out, or one applied to the surface of the heat-fusible resin layer 4.

The thickness of the heat-fusible resin layer 4 may be set to the predetermined thickness described above, depending on the presence or absence of the adhesive layer 5, the thickness of the adhesive layer 5, and the like, as well as the thickness of the base layer 1 and the barrier layer 3, which constitute the outer packaging material for an electric storage device. The thickness of the heat-fusible resin layer 4 is, for example, about 33 μm or less, about 30 μm or less, about 20 μm or less, about 17 μm or less, about 15 μm or less, or the like. The thickness of the heat-fusible resin layer 4 is about 8 μm or more, about 10 μm or more, about 15 μm or more, about 20 μm or more, about 22 μm or more, about 25 μm or more, about 28 μm or more, and the like. The preferable range of the thickness of the heat-fusible resin layer 4 may be about 8 to 33 μm, about 8 to 30 μm, about 8 to 20 μm, about 8 to 17 μm, about 8 to 15 μm, about 10 to 33 μm, about 10 to 30 μm, about 10 to 20 μm, about 10 to 17 μm, about 10 to 15 μm, about 15 to 33 μm, about 15 to 30 μm, about 15 to 20 μm, about 15 to 17 μm, about 20 to 33 μm, about 20 to 30 μm, about 22 to 33 μm, about 22 to 30 μm, about 25 to 33 μm, about 25 to 30 μm, about 28 to 33 μm, about 28 to 30 μm, and the like.

In particular, when the thickness of the adhesive layer 5 to be described later is in the range of 12 to 17 μm, the thickness of the heat-fusible resin layer 4 is preferably about 17 μm or less, and more preferably about 15 μm or less. When the thickness of the adhesive layer 5 to be described later is within a range of 12 to 17 μm, the thickness of the heat-fusible resin layer 4 is preferably about 8 μm or more, and more preferably 10 μm or more. When the thickness of the adhesive layer 5 to be described later is within a range of 12 to 17 μm, preferable ranges of the thickness of the heat-fusible resin layer 4 include about 8 to 17 μm, about 8 to 15 μm, about 10 to 17 μm, and about 10 to 15 μm.

When the thickness of the adhesive layer 5 to be described later is in the range of 1 to 5 μm, the thickness of the heat-sealable resin layer 4 is preferably about 22 μm or more, more preferably about 25 μm or more, and still more preferably about 28 μm or more. When the thickness of the adhesive layer 5 to be described later is in the range of 1 to 5 μm, the thickness of the heat-fusible resin layer 4 is preferably about 33 μm or less, and more preferably about 30 μm or less. When the thickness of the adhesive layer 5 to be described later is in the range of 1 to 5 μm, the thickness of the heat-fusible resin layer 4 is preferably in the range of about 22 to 33 μm, about 22 to 30 μm, about 25 to 33 μm, about 25 to 30 μm, about 28 to 33 μm, and about 28 to 30 μm.

[ adhesive layer 5]

In the outer covering material for an electric storage device of the present invention, the adhesive layer 5 is a layer provided between the barrier layer 3 (or the corrosion-resistant film) and the heat-fusible resin layer 4 as necessary to strongly adhere the layers.

The adhesive layer 5 is formed of a resin capable of bonding the barrier layer 3 and the heat-fusible resin layer 4. As the resin for forming the adhesive layer 5, for example, the same resin as the adhesive exemplified in the adhesive layer 2 can be used. From the viewpoint of firmly bonding the adhesive layer 5 and the heat-fusible resin layer 4, the resin for forming the adhesive layer 5 preferably contains a polyolefin skeleton, and examples thereof include polyolefins and acid-modified polyolefins exemplified for the heat-fusible resin layer 4. On the other hand, the adhesive layer 5 preferably contains an acid-modified polyolefin from the viewpoint of firmly bonding the barrier layer 3 and the adhesive layer 5. Examples of the acid-modifying component include dicarboxylic acids such as maleic acid, itaconic acid, succinic acid, and adipic acid, and anhydrides thereof, acrylic acid, and methacrylic acid, and maleic anhydride is most preferable from the viewpoint of ease of modification, versatility, and the like. In addition, from the viewpoint of heat resistance of the outer covering material for an electricity storage device, the olefin component is preferably a polypropylene resin, and the adhesive layer 5 most preferably contains maleic anhydride-modified polypropylene.

The resin constituting the adhesive layer 5 containing 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 resin constituting the adhesive layer 5 contains an acid-modified polyolefin, for example, in the followingWhen the wave number of the maleic anhydride modified polyolefin is measured by infrared spectroscopy, the wave number is 1760cm ^-1 Neighborhood and wavenumber 1780cm ^-1 A peak derived from maleic anhydride was detected nearby. However, when the degree of acid modification is low, it may not be detected because the peak value is small. In this case, the analysis can be performed by nuclear magnetic resonance spectroscopy.

The adhesive layer 5 is more preferably a cured product of a resin composition containing an acid-modified polyolefin and a curing agent, from the viewpoints of durability such as heat resistance and content resistance of an outer packaging material for an electric storage device, and reduction in thickness and ensuring moldability. As the acid-modified polyolefin, the above-exemplified compounds are preferred.

The adhesive layer 5 is preferably a cured product of a resin composition containing an acid-modified polyolefin and at least 1 selected from a compound having an isocyanate group, a compound having an oxazoline group, and a compound having an epoxy group, and particularly preferably a cured product of a resin composition containing an acid-modified polyolefin and at least 1 selected from a compound having an isocyanate group and a compound having an epoxy group. In addition, the adhesive layer 5 preferably contains at least 1 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 of an epoxy group and a maleic anhydride group, and an amide ester resin produced by a reaction of an oxazoline group and a maleic anhydride group are preferable. When an unreacted material of a compound having an isocyanate group, a compound having an oxazoline group, or a curing agent such as an epoxy resin remains in the adhesive layer 5, the presence of the unreacted material can be confirmed by a method selected from infrared spectroscopy, raman spectroscopy, time-of-flight secondary ion mass spectrometry (TOF-SIMS), and the like.

From the viewpoint of further improving the adhesion between the barrier layer 3 and the adhesive layer 5, the adhesive layer 5 is preferably a cured product of a resin composition containing at least 1 kind of curing agent selected from an oxygen atom, a heterocycle, a C ═ N bond, and a C — O — C bond. Examples of the curing agent having a heterocyclic ring include a curing agent having an oxazoline group, a curing agent having an epoxy group, and the like. Examples of the curing agent having a C ═ N bond include a curing agent having an oxazoline group and a curing agent having an isocyanate group. Examples of the curing agent having a C — O — C bond include a curing agent having an oxazoline group, a curing agent having an epoxy group, and the like. The fact that the adhesive layer 5 is a cured product of a resin composition containing such a curing agent can be confirmed by a method such as Gas Chromatography Mass Spectrometry (GCMS), infrared spectroscopy (IR), time-of-flight secondary ion mass spectrometry (TOF-SIMS), or X-ray photoelectron spectroscopy (XPS).

The compound having an isocyanate group is not particularly limited, and a polyfunctional isocyanate compound is preferably used from the viewpoint of effectively improving the adhesion between the barrier layer 3 and the adhesive layer 5. The polyfunctional isocyanate compound is not particularly limited as long as it has 2 or more isocyanate groups. Specific examples of the polyfunctional isocyanate-based curing agent include Pentamethylene Diisocyanate (PDI), isophorone diisocyanate (IPDI), Hexamethylene Diisocyanate (HDI), Toluene Diisocyanate (TDI), diphenylmethane diisocyanate (MDI), compounds obtained by polymerizing or urethanizing these compounds, mixtures thereof, and copolymers with other polymers. Further, adducts, biuret products, isocyanurate products and the like can be cited.

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. This can effectively improve the adhesion between the barrier layer 3 and the adhesive layer 5.

The oxazoline group-containing compound is not particularly limited as long as it is a compound having an oxazoline skeleton. Specific examples of the oxazoline group-containing compound include a compound having a polystyrene main chain, a compound having an acrylic main chain, and the like. Examples of commercially available products include Epocros series products manufactured by Nippon catalyst Co., Ltd.

The proportion of the oxazoline group-containing compound in the adhesive layer 5 is preferably in the range of 0.1 to 50 mass%, more preferably in the range of 0.5 to 40 mass% in the resin composition constituting the adhesive layer 5. This can effectively improve the adhesion between the barrier layer 3 and the adhesive layer 5.

Examples of the compound having an epoxy group include epoxy resins. The epoxy resin is not particularly limited as long as it is a resin capable of forming a crosslinked structure by epoxy groups present in the molecule, and a known epoxy resin can be used. The weight average molecular weight of the epoxy resin is preferably about 50 to 2000, more preferably about 100 to 1000, and further preferably about 200 to 800. Wherein, in the first invention, the weight average molecular weight of the epoxy resin is a value measured by Gel Permeation Chromatography (GPC) under the condition that polystyrene is used as a standard sample.

Specific examples of the epoxy resin include glycidyl ether derivatives of trimethylolpropane, bisphenol a diglycidyl ether, modified bisphenol a diglycidyl ether, bisphenol F type glycidyl ether, novolak glycidyl ether, glycerol polyglycidyl ether, polyglycerol polyglycidyl ether, and the like. The epoxy resin may be used alone in 1 kind, or 2 or more kinds may be used in combination.

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

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

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

In addition, when the adhesive layer 5 is a cured product of a resin composition containing at least 1 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 function as curing agents, respectively.

The adhesive layer 5 may contain a modifier having a carbodiimide group.

The thickness of the adhesive layer 5 may be set to the predetermined thickness described above, and may be set according to the thickness of the heat-fusible resin layer 4, or the like, as well as the thickness of the laminate constituting the outer covering material for an electric storage device, the thickness of the base material layer 1, and the thickness of the barrier layer 3. The thickness of the adhesive layer 5 is, for example, about 17 μm or less, about 16 μm or less, about 15 μm or less, about 8 μm or less, about 5 μm or less, about 3 μm or less, or the like. The thickness of the adhesive layer 5 is, for example, about 1 μm or more, about 3 μm or more, about 8 μm or more, about 10 μm or more, about 12 μm or more, about 15 μm or more, or the like. The preferable range of the thickness of the adhesive layer is, for example, about 1 to 17 μm, about 1 to 16 μm, about 1 to 15 μm, about 1 to 8 μm, about 1 to 5 μm, about 1 to 3 μm, about 3 to 17 μm, about 3 to 16 μm, about 3 to 15 μm, about 3 to 8 μm, about 3 to 5 μm, about 8 to 17 μm, about 8 to 16 μm, about 8 to 15 μm, about 10 to 17 μm, about 10 to 16 μm, about 10 to 15 μm, about 12 to 17 μm, about 12 to 16 μm, about 12 to 15 μm, about 15 to 17 μm, about 15 to 16 μm, and the like.

Particularly, when the thickness of the heat-fusible resin layer 4 is 8 to 17 μm, the thickness of the adhesive layer 5 is preferably about 12 μm or more, and more preferably about 15 μm or more. When the thickness of the heat-fusible resin layer 4 is 8 to 17 μm, the thickness of the adhesive layer 5 is preferably about 17 μm or less, and more preferably about 16 μm or less. When the thickness of the heat-fusible resin layer 4 is 8 to 17 μm, the preferable range of the thickness of the adhesive layer 5 is about 12 to 17 μm, about 12 to 16 μm, about 15 to 17 μm, and about 15 to 16 μm.

When the thickness of the heat-fusible resin layer 4 is 22 to 33 μm, the thickness of the adhesive layer 5 is preferably about 5 μm or less. When the thickness of the heat-fusible resin layer 4 is 22 to 33 μm, the thickness of the adhesive layer 5 is preferably about 1 μm or more, and more preferably about 3 μm or more. In this case, as the adhesive layer 5, it is preferable to use the acid-modified polyolefin exemplified in the heat-fusible resin layer 4. When the thickness of the heat-fusible resin layer 4 is 22 to 33 μm, the thickness of the adhesive layer 5 is preferably about 1 to 5 μm, more preferably about 3 to 5 μm. In this case, as the adhesive layer 5, a cured product of the acid-modified polyolefin and the curing agent, and an adhesive similar to the adhesive exemplified in the adhesive layer 2 are preferably used.

[ surface coating layer 6]

In order to improve at least one of design properties, electrolyte resistance, scratch resistance, moldability, and the like, the outer packaging material for an electric storage device of the present invention may have a surface-covering layer 6 on the base material layer 1 (on the side of the base material layer 1 opposite to the barrier layer 3), as necessary. The surface-covering layer 6 is a layer located on the outermost layer side of the outer packaging material for an electric storage device when the electric storage device is assembled using the outer packaging material for an electric storage device.

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

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

Examples of the two-liquid curable polyurethane include polyurethanes containing a main agent containing a polyol compound and a curing agent containing an isocyanate compound. Preferred examples of the two-liquid curable polyurethane include two-liquid curable polyurethanes containing a polyol such as a polyester polyol, a polyether polyol and an acrylic polyol as a main component and an aromatic or aliphatic polyisocyanate as a curing agent. In addition, as the polyol compound, a polyester polyol having a hydroxyl group in a side chain in addition to a hydroxyl group at the terminal of the repeating unit is preferably used. Examples of the curing agent include aliphatic, alicyclic, aromatic, and araliphatic isocyanate compounds. Examples of the isocyanate compound include Hexamethylene Diisocyanate (HDI), Xylene Diisocyanate (XDI), isophorone diisocyanate (IPDI), hydrogenated XDI (H6XDI), hydrogenated MDI (H12MDI), Toluene Diisocyanate (TDI), diphenylmethane diisocyanate (MDI), and Naphthalene Diisocyanate (NDI). Also, 1 or 2 or more kinds of modified polyfunctional isocyanates derived from these diisocyanates, and the like can be mentioned. In addition, as the polyisocyanate compound, multimers (e.g., trimers) can also be used. Examples of such polymers include adducts, biuret polymers, and urea acid ester polymers. The aliphatic isocyanate compound is an isocyanate having an aliphatic group and no aromatic ring, the alicyclic isocyanate compound is an isocyanate having an alicyclic hydrocarbon group, and the aromatic isocyanate compound is an isocyanate having an aromatic ring. The surface-covering layer 6 is formed of polyurethane, and thus can impart excellent electrolyte resistance to the outer covering material for an electric storage device.

The thickness of the surface-covering layer 6 is not particularly limited as long as the above-described function as the surface-covering layer 6 can be exhibited, and the thickness of the laminate constituting the outer packaging material for an electricity storage device, the thickness of the base material layer 1, and the thickness of the barrier layer 3 are set to the predetermined thicknesses, and is, for example, about 0.1 μm or more, about 0.5 μm or more, about 1 μm or more, and about 2 μm or more. The thickness of the surface coating layer 6 is, for example, about 5 μm or less, about 4 μm or less, and about 3 μm or less. Preferable ranges of the thickness of the surface-covering layer 6 include about 0.1 to 5 μm, about 0.1 to 4 μm, about 0.1 to 3 μm, about 0.5 to 5 μm, about 0.5 to 4 μm, about 0.5 to 3 μm, about 1 to 5 μm, about 1 to 4 μm, about 1 to 3 μm, about 2 to 5 μm, about 2 to 4 μm, and about 2 to 3 μm.

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

The additive may be any of inorganic and organic. The shape of the additive is also not particularly limited, and examples thereof include spherical, fibrous, plate-like, amorphous, and scaly shapes.

Specific examples of the additive include talc, silica, graphite, kaolin, montmorillonite, mica, hydrotalcite, silica gel, zeolite, aluminum hydroxide, magnesium hydroxide, zinc oxide, magnesium oxide, aluminum oxide, neodymium oxide, antimony oxide, titanium oxide, cerium oxide, calcium sulfate, barium sulfate, calcium carbonate, calcium silicate, lithium carbonate, calcium benzoate, calcium oxalate, magnesium stearate, aluminum oxide, carbon black, carbon nanotubes, high-melting nylon, acrylate resins, crosslinked acrylic acid, crosslinked styrene, crosslinked polyethylene, benzoguanamine, gold, aluminum, copper, nickel, and the like. The additive may be used alone in 1 kind, or 2 or more kinds may be used in combination. Among these additives, silica, barium sulfate, and titanium oxide are preferable from the viewpoints of dispersion stability, cost, and the like. The surface of the additive may be subjected to various surface treatments such as an insulating treatment and a high-dispersibility treatment.

The method for forming the surface-covering layer 6 is not particularly limited, and for example, a method of applying a resin for forming the surface-covering layer 6 is mentioned. When the additive is blended in the surface coating layer 6, a resin mixed with the additive may be applied.

The lubricant present on the surface of the surface-covering layer 6 may be a lubricant exuded from a resin constituting the base material layer 1, or a lubricant applied to the surface of the base material layer 1. The lubricant present on the surface of the surface-covering layer 6 may be transferred to the surface of the surface-covering layer 6 in a state where the outer material for an electric storage device is in the form of a wound body wound around a winding core or the like, and the lubricant present on the surface of the heat-fusible resin layer 4.

3. Method for producing outer packaging material for electricity storage device

The method for producing the outer packaging material for an electric storage device is not particularly limited as long as a laminate obtained by laminating the layers of the outer packaging material for an electric storage device of the present invention can be obtained, and a method including a step of sequentially laminating at least the base layer 1, the barrier layer 3, and the heat-fusible resin layer 4 may be mentioned. That is, the method for producing an outer packaging material for an electricity storage device according to the present invention includes a step of sequentially laminating at least a base material layer, a barrier layer, and a heat-fusible resin layer to obtain a laminate, wherein the base material layer has a thickness of 18 μm to 22 μm, the barrier layer has a thickness of 27 μm to 38 μm, and the laminate has a thickness of 100 μm.

An example of a method for manufacturing an outer casing for an electric storage device according to the present invention is as follows. First, a laminate (hereinafter, may be referred to as "laminate a") in which a base material layer 1, an adhesive layer 2, and a barrier layer 3 are sequentially laminated is formed. Specifically, the laminate a can be formed by a dry lamination method as follows: an adhesive for forming the adhesive layer 2 is applied on the base material layer 1 or the barrier layer 3 whose surface is chemically treated as necessary by a coating method such as a gravure coating method or a roll coating method and dried, and then the barrier layer 3 or the base material layer 1 is laminated and the adhesive layer 2 is cured.

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 may be laminated on the barrier layer 3 of the laminate a by a heat lamination method, an extrusion lamination method, or the like. In addition, when the adhesive layer 5 is provided between the barrier layer 3 and the heat-fusible resin layer 4, for example, the following methods can be mentioned: (1) a method of extruding the adhesive layer 5 and the heat-fusible resin layer 4 to laminate the barrier layer 3 of the laminate a (co-extrusion lamination method, tandem lamination method); (2) a method of forming a laminate in which the adhesive layer 5 and the heat-fusible resin layer 4 are laminated on each other and laminating the laminate on the barrier layer 3 of the laminate A by a heat lamination method, or a method of forming a laminate in which the adhesive layer 5 is laminated on the barrier layer 3 of the laminate A and laminating the laminate and the heat-fusible resin layer 4 by a heat lamination method; (3) a method (interlayer lamination method) in which a molten adhesive layer 5 is injected between the barrier layer 3 of the laminate a and the heat-fusible resin layer 4 formed in a sheet shape in advance, and the laminate a and the heat-fusible resin layer 4 are bonded to each other with the adhesive layer 5; (4) a method of applying an adhesive for forming the adhesive layer 5 to the barrier layer 3 of the laminate a in a solution, drying the adhesive or further baking the adhesive to laminate the layers, and laminating the heat-fusible resin layer 4 previously formed into a sheet shape on the adhesive layer 5.

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

As described above, a laminate having the surface covering layer 6, the base material layer 1, the adhesive layer 2, the barrier layer 3, the adhesive layer 5, and the heat-fusible resin layer 4, which are provided as necessary, in this order, may be formed, and may be subjected to heat treatment in order to enhance the adhesiveness between the adhesive layer 2 and the adhesive layer 5, which are provided as necessary.

In the outer packaging material for an electricity storage device, each layer constituting the laminate may be subjected to surface activation treatment such as corona treatment, blast treatment, acidification treatment, ozone treatment, or the like, as necessary, to thereby improve the processing suitability. For example, by performing corona treatment on the surface of the base material layer 1 opposite to the barrier layer 3, the printing suitability of the ink on the surface of the base material layer 1 can be improved.

4. Use of outer packaging material for electricity storage device

The outer package for an electric storage device of the present invention is used for a package for sealing and housing electric storage device elements such as a positive electrode, a negative electrode, and an electrolyte. That is, the electric storage device element having at least a positive electrode, a negative electrode, and an electrolyte may be housed in a package formed of the outer packaging material for an electric storage device of the present invention to form an electric storage device.

Specifically, the present invention provides an electric storage device using an outer covering material for an electric storage device, in which an electric storage device element having at least a positive electrode, a negative electrode, and an electrolyte is covered so that a flange portion (a region where heat-fusible resin layers are in contact with each other) can be formed on the periphery of the electric storage device element in a state where metal terminals to which the positive electrode and the negative electrode are connected are protruded outward, and the heat-fusible resin layers of the flange portion are heat-sealed with each other. When the electric storage device element is housed in the package formed of the electric storage device exterior material of the present invention, the heat-fusible resin portion of the electric storage device exterior material of the present invention is on the inner side (the surface in contact with the electric storage device element), and the package is formed. The outer package may be formed by laminating the heat-fusible resin layers of the two outer packages for electric storage devices so as to face each other and heat-fusing the peripheral portions of the laminated outer packages for electric storage devices, or may be formed by folding and laminating one outer package for electric storage devices and heat-fusing the peripheral portions, as in the example shown in fig. 5. When folded, the other edges than the folded edges may be heat-welded to form a package by three-side sealing as in the example shown in fig. 5; the flange portion may be folded to form a four-sided seal. In addition, in the outer covering material for an electric storage device, a concave portion for housing the electric storage device element may be formed by deep drawing or stretch forming. As in the example shown in fig. 5, a recess may be provided in one electric storage device outer cover, and no recess may be provided in the other electric storage device outer cover, or a recess may be provided in the other electric storage device outer cover.

The outer package for an electric storage device of the present invention can be applied to an electric storage device such as a battery (including a capacitor or a capacitor). The outer packaging material for an electric storage device of the present invention can be used for both primary batteries and secondary batteries, and is preferably used for secondary batteries. The type of secondary battery to which the outer covering material for an electric storage device of the present invention is applied is not particularly limited, and examples thereof include a lithium ion battery, a lithium ion polymer battery, an all-solid battery, a lead storage battery, a nickel-hydrogen storage battery, a nickel-cadmium storage battery, a nickel-iron storage battery, a nickel-zinc storage battery, a silver oxide-zinc storage battery, a metal air battery, a polyvalent cation battery, a capacitor element (capacitor), and a capacitor (capacitor). Among these secondary batteries, lithium ion batteries and lithium ion polymer batteries are preferable examples of applications of the outer cover for electric storage devices of the present invention.

Examples

The present invention will be described in detail below by way of examples and comparative examples. However, the present invention is not limited to the examples.

< production of outer packaging Material for Power storage device >

Examples 1 to 8 and comparative examples 1 to 8

Each of the outer packaging materials for the electricity storage device was produced according to the following procedure, according to the material and thickness of each layer described in table 1. A biaxially stretched nylon film (thickness shown in Ny Table 1) as a base material layer and an aluminum foil (thickness shown in Table 1, JIS H4160: 1994A 8021H-O) as a barrier layer on both surfaces of which an acid-resistant coating film was formed were prepared. Among these, the biaxially stretched nylon films used in examples 1 to 8 had a crystallinity of 1.72, and the biaxially stretched nylon films used in comparative examples 1 to 4 had a crystallinity of 1.68. The crystallinity was measured by the above method using a device that uses a biaxially stretched nylon film laminated on an outer packaging material for an electric storage device as a measurement target, and Nicolet iS10 manufactured by Thermo Fisher Scientific, inc. As the aluminum foil, two aluminum foils different in distributor were used. The substrate layer and the barrier layer are laminated by a dry lamination method. Specifically, a two-pack curable polyurethane adhesive (a polyol compound and an aromatic isocyanate compound) was applied to one surface of an aluminum foil having acid-resistant films formed on both surfaces thereof, and an adhesive layer (thickness after curing: 3 μm) was formed on the aluminum foil. Next, the adhesive layer on the aluminum foil and the biaxially stretched nylon film were laminated, and then subjected to aging treatment to prepare a laminate of a base layer/adhesive layer/barrier layer. In examples 2 and 6, a two-liquid curable polyurethane adhesive (black pigment, polyol compound and aromatic isocyanate compound) containing a black pigment was used instead of the two-liquid curable polyurethane adhesive (polyol compound and aromatic isocyanate compound) for bonding the base layer and the barrier layer.

Next, in examples 1, 3, 5, and 7 and comparative examples 1 to 8, maleic anhydride-modified polypropylene (PPa, thickness described in table 1) as an adhesive layer and polypropylene (PP, thickness described in table 1) as a heat-fusible resin layer were coextruded on the barrier layer of the obtained laminate, and the adhesive layer/heat-fusible resin layer was laminated on the barrier layer. Next, the obtained laminate was subjected to aging treatment and heating, thereby obtaining an outer covering material for an electric storage device (total thickness shown in table 1) in which a biaxially stretched nylon film/adhesive layer/barrier layer/adhesive layer/heat-fusible resin layer were sequentially laminated.

In examples 2 and 6, on the barrier layer of the obtained laminate, maleic anhydride-modified polypropylene (PPa, thickness described in table 1) as an adhesive layer and polypropylene (PP, thickness described in table 1) as a heat-fusible resin layer were coextruded to laminate an adhesive layer/heat-fusible resin layer on the barrier layer. Further, a resin composition (thickness after curing: 3 μm) containing silica and erucamide having an average particle size of 1.5 μm as fillers and a styrene-based resin having an average particle size of 2.5 μm as additives was applied to the surface of the biaxially stretched nylon film of the obtained laminate by gravure coating to form a matte-finished surface coating layer, and a surface coating layer/biaxially stretched nylon film/adhesive layer/barrier layer/adhesive layer/heat-fusible resin layer was sequentially laminated to obtain an outer covering material for an electric storage device (total thickness described in table 1). Wherein the average particle diameter of the silica is a median particle diameter measured by a laser diffraction/scattering particle size distribution measuring apparatus ("LA-950" manufactured by horiba Ltd.).

In examples 4 and 8, a two-pack curing type adhesive (acid-modified polypropylene and epoxy compound) was applied to the barrier layer of the laminate of the base layer/adhesive layer/barrier layer to form an adhesive layer (thickness after curing: 3 μm) on the aluminum foil. Further, an unstretched polypropylene film (CPP, thickness described in table 1) as a heat-fusible resin layer was laminated from above the adhesive layer by a dry lamination method. Then, the obtained laminate was subjected to aging treatment and heated to obtain an outer covering material for an electric storage device (total thickness shown in table 1) in which a biaxially stretched nylon film/adhesive layer/barrier layer/adhesive layer/heat-fusible resin layer were sequentially laminated.

Here, erucamide as a lubricant was applied to the outer surface of the base layer of each of the outer packaging materials for electricity storage devices of examples 1, 3 to 5, 7, and 8 and comparative examples 1 to 8.

< coefficient of dynamic Friction of outer surface >

The dynamic friction coefficient of the outer surface (surface on the base material layer side) of the outer packaging material for an electricity storage device obtained in examples and comparative examples was measured as follows. Friction test according to JIS K7125: 1999 8.1, film-to-film assay. First, two samples of each of the outer packaging materials for electric storage devices obtained as described above were cut out to have a TD dimension of 80mm × a MD dimension of 200 mm. The samples were then stacked with the outer surfaces facing each other, and a slide was placed thereon. Rubber is adhered to the bottom surface of the sliding sheet, so that the total mass of the sliding sheet is 200g, and the sample is tightly attached to the sliding sheet so as to avoid slipping. Then, the slide piece was pulled at a speed of 100 mm/min, the sliding friction force (N) between the two samples was measured, and the sliding friction force was divided by the normal force (1.96N) of the slide piece to calculate the coefficient of kinetic friction. The coefficient of kinetic friction was determined from the average value of the first 30mm after the relative displacement motion between the contact surfaces was started, ignoring the peak value of the static friction force. And, the load cell is directly connected to the slider. The obtained results were evaluated according to the following criteria. The results are shown in Table 1.

< evaluation of curling due to Molding >

The outer packaging material for electric storage devices obtained above was cut into a strip-shaped piece having a TD (Transverse Direction: vertical Direction) of 150mm × MD (Machine Direction: mechanical Direction) of 90mm, and this was used as a test sample. A mold composed of a rectangular male mold (surface 1.6 mm. times.54.5 mm, nominal value of Rz, corner R2.0mm, ridge line R1.0mm) specified in Table 2 of the surface roughness standard sheet for comparison in accordance with JIS B0659-1: 2002 attachment 1 (reference) and a female mold (surface 0.3mm apart from the male mold (surface 3mm, nominal value of Rz, corner R2.0mm, ridge line R1.0mm) specified in Table 2 of the surface roughness standard sheet for comparison in accordance with JIS B0659-1: 2002 attachment 1 (reference)) was used, the above test sample was placed on the female mold with the heat-sealable resin layer side on the male mold side, the test specimen was pressed with a pressing force (surface pressure) of 0.25MPa to perform cold forming (drawing 1 stage forming), so as to be 31.6Mm (MD) by 54.5mm (TD) and 6mm in molding depth. The details of the location where the forming takes place are shown in figure 6. As shown in fig. 6, the rectangular molded portion M is molded at a position where the shortest distance d between the end portion P of the outer package 10 for an electric storage device is 70.5 mm. The molding portion M indicates a position where the concave portion is formed by the mold. Next, as shown in fig. 7, the molded outer cover 10 for an electric storage device was placed on a horizontal surface 20, and the maximum value t of the distance in the vertical direction y from the horizontal surface 20 to the end P was set as the maximum height of the curl portion (the corner showing the maximum height among the four corners of the test sample). The smaller the value of curl due to molding, the smaller the curl, and the better the outer packaging material for electricity storage devices. The formed curl (mm) is a value obtained by rounding off the second decimal place of the maximum value t. The molded curl was evaluated according to the following criteria. The results are shown in Table 1.

A +: the forming curl is 0mm or more and less than 15mm, the forming curl is small, and the productivity is hardly lowered.

A: the forming curl is 15mm or more and less than 25mm, and the forming curl is slightly large, but the reduction of productivity is small.

B: the forming curl is 25mm or more and less than 35mm, the forming curl is large, and the reduction of productivity is large.

C: the molding curl was 35mm or more, the molding curl was extremely large, and the productivity was extremely reduced.

[ evaluation of mechanical Strength ]

The mechanical strength of the outer packaging material for an electricity storage device was evaluated by the following measurement of puncture strength and 4-fold test. The results of the tests are shown in Table 1.

< puncture Strength >

Using ZP-50N (dynamometer) manufactured by IMADA and MX2-500N (measurement bench) manufactured by IMADA, the following were prepared in accordance with JIS Z1707: 1997, the strength of the penetration from the outer surface side (base layer side or surface coating layer side) of the laminate constituting the outer packaging material for an electricity storage device was measured. Specifically, in a measuring environment at 23. + -. 2 ℃ and a relative humidity of 50. + -.5%, a test piece was fixed by a stage having an opening of 15mm in diameter at the center and having a diameter of 115mm and a pressing plate, and a semicircular needle having a diameter of 1.0mm and a tip shape radius of 0.5mm was used to puncture the test piece at a speed of 50. + -.5 mm per minute, and the maximum stress until the needle tip was penetrated was measured. The number of test pieces was 10, and the average value was obtained. When the number of test pieces is insufficient and 10 cannot be measured, the measurable number is measured, and the average value is obtained. The evaluation criteria are as follows.

A +: the puncture strength is above 23N.

A: the puncture strength is above 19N and below 23N.

B: the puncture strength is 18N or more and less than 19N.

C: the puncture strength was below 18N.

<4 fold test >

The outer packaging material for electric storage devices obtained above was cut into a strip-shaped piece having a TD (Transverse Direction: vertical Direction) of 150mm × MD (Machine Direction: mechanical Direction) of 90mm, and this was used as a test sample. The test sample was folded into 4 folds 10 times, and the number of times until a pinhole was formed in the center portion was measured. The operation of folding 4 folds is performed by folding the center positions of the heat-fusible resin layers in the TD direction so that the short sides (the sides in the MD direction) of the test sample overlap each other, folding the center positions in two, folding the center positions of the test sample in 4 folds so that the sides in the TD direction overlap each other in the MD direction, and folding the center positions of the test sample in 4 folds. The test sample was folded and unfolded at 4 folds, and the same operation of folding and unfolding the test sample was repeated to carry out the test. The number of test samples was 5, and the number of pinholes formed in the center portion was averaged. When the number of test samples is insufficient and 5 cannot be measured, the measurable number is measured and the average value is obtained. The evaluation criteria are as follows.

A +: the number of times until the center portion forms a pinhole is 7 or more.

A: the number of times until the center portion forms a pinhole is 5 to 6 times.

B: the number of times until the center portion forms a pinhole is 2 to 4 times.

C: the number of times until the center portion formed a pinhole was 1.

[ Table 1]

In table 1, "ONy" means a biaxially stretched nylon film, "polyurethane" means an adhesive layer formed of a two-liquid curable polyurethane adhesive by a dry lamination method, and "ALM a" and "ALM B" mean aluminum foil, respectively.

As shown in table 1, the outer packaging materials for electricity storage devices of examples 1 to 8 were each composed of a laminate including at least a base material layer, a barrier layer, and a heat-sealable resin layer in this order, the base material layer had a thickness of 18 μm to 22 μm, the barrier layer had a thickness of 27 μm to 38 μm, and the laminate had a thickness of 100 μm. It is found that the outer packaging materials for electricity storage devices of examples 1 to 8 have high mechanical strength while suppressing curling due to molding, even though the thickness is as thin as 100 μm or less.

As described above, the present invention provides the following inventions.

Item 1: an outer package for an electricity storage device, comprising a laminate having at least a base material layer, a barrier layer, and a heat-sealable resin layer in this order, wherein the base material layer has a thickness of 18 [ mu ] m to 22 [ mu ] m, the barrier layer has a thickness of 27 [ mu ] m to 38 [ mu ] m, and the laminate has a thickness of 100 [ mu ] m.

Item 2: the outer packaging material for an electric storage device according to claim 1, wherein an adhesive layer is provided between the barrier layer and the heat-fusible resin layer, the adhesive layer has a thickness of 12 μm to 17 μm, and the heat-fusible resin layer has a thickness of 8 μm to 17 μm.

Item 3: the outer packaging material for an electric storage device according to claim 1, wherein an adhesive layer is provided between the barrier layer and the heat-fusible resin layer, the adhesive layer has a thickness of 1 μm to 5 μm, and the heat-fusible resin layer has a thickness of 22 μm to 33 μm.

Item 4: the outer packaging material for power storage devices according to any one of claims 1 to 3, further comprising a surface coating layer on a side of the base material layer opposite to the barrier layer side.

Item 5: an electric storage device, wherein an electric storage device element having at least a positive electrode, a negative electrode and an electrolyte is housed in a package formed of the outer packaging material for electric storage devices described in any one of items 1 to 4.

Item 6: a method for producing an outer packaging material for an electricity storage device, comprising a step of sequentially laminating at least a base material layer, a barrier layer and a heat-sealable resin layer to obtain a laminate, wherein the thickness of the base material layer is 18 [ mu ] m or more and 22 [ mu ] m or less, the thickness of the barrier layer is 27 [ mu ] m or more and 38 [ mu ] m or less, and the thickness of the laminate is 100 [ mu ] m or less.

Description of the symbols

1: a substrate layer; 2: an adhesive layer; 3: a barrier layer; 4: a heat-fusible resin layer; 5: an adhesive layer; 6: a surface covering layer; 10: an outer packaging material for an electricity storage device.

Claims

1. An outer packaging material for an electricity storage device, characterized in that,

comprising a laminate comprising at least a base material layer, a barrier layer and a heat-sealable resin layer in this order,

the thickness of the substrate layer is 18-22 μm,

the thickness of the barrier layer is 27 μm to 38 μm,

the thickness of the laminate is 100 μm or less.

2. The outer packaging material for an electricity storage device according to claim 1,

an adhesive layer is provided between the barrier layer and the heat-fusible resin layer,

the thickness of the adhesive layer is 12-17 μm,

the thickness of the heat-sealing resin layer is 8-17 μm.

3. The outer packaging material for an electricity storage device according to claim 1,

the thickness of the adhesive layer is 1-5 μm,

the thickness of the heat-sealing resin layer is 22-33 μm.

4. The outer packaging material for electricity storage devices according to any one of claims 1 to 3,

the substrate layer further has a surface covering layer on the side opposite to the barrier layer side.

5. An electricity storage device characterized in that,

an electric storage device element having at least a positive electrode, a negative electrode, and an electrolyte is housed in a package formed of the outer packaging material for an electric storage device according to any one of claims 1 to 4.

6. A method for producing an outer packaging material for electricity storage devices, characterized in that,

comprises a step of sequentially laminating at least a base material layer, a barrier layer and a heat-fusible resin layer to obtain a laminate,

the thickness of the substrate layer is 18-22 μm,

the thickness of the barrier layer is 27 μm to 38 μm,

the thickness of the laminate is 100 μm or less.