JP7722196B2 - Exterior material for power storage device, manufacturing method thereof, and power storage device - Google Patents

Description

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

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

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

In recent years, therefore, a film-like packaging material consisting of a substrate, an aluminum foil layer, and a heat-sealable resin layer laminated in that order has been proposed as a packaging material for electricity storage devices that can be easily processed into a variety of shapes and can be made thinner and lighter (see, for example, Patent Document 1).

In such film-like exterior materials, recesses are generally formed by cold forming, and energy storage device elements such as electrodes and electrolyte are placed in the spaces formed by the recesses. The heat-sealable resin layers are then heat-sealed together to obtain an energy storage device in which the energy storage device elements are housed inside the exterior material.

Japanese Patent Application Laid-Open No. 2008-287971

In recent years, there has been a demand for thinner film exterior materials. Furthermore, in order to further increase the energy density of energy storage devices, there is also a demand for the formation of deeper recesses in the exterior materials.

However, the inventors have conducted research and found that when an exterior material for an electricity storage device is made by sequentially laminating a base material layer, a barrier layer, and a heat-sealable resin layer, and this is molded to form a recess for accommodating an electricity storage device element, if the thickness of the exterior material for an electricity storage device is reduced to 100 μm or less, the peripheral edge of the recess may curl (bend) during molding, hindering the accommodation of the electricity storage device element and the heat-sealing of the heat-sealable resin layer, and potentially reducing the production efficiency of the electricity storage device.

In particular, energy storage devices used in small devices such as personal computers, cameras, and mobile phones require the formation of small, deep recesses in thin exterior materials, which can result in significant curling due to molding.

Furthermore, if the thickness of the exterior material for an electricity storage device becomes as thin as 100 μm or less, the mechanical strength decreases, and there is a risk that the electricity storage device elements may not be adequately protected, for example, if an external impact is applied to the electricity storage device (for example, if the electricity storage device is dropped).

Under these circumstances, the main objective of this disclosure is to provide an exterior material for an electricity storage device that, despite its thin thickness of 100 μm or less, suppresses curling during molding and has high mechanical strength.

To solve the above-mentioned problems, the present inventors conducted extensive research into suppressing curl during molding and improving mechanical strength in an electrical storage device exterior packaging material designed to have a thickness of 100 μm or less, focusing on the laminate structure of the electrical storage device exterior packaging material. As a result, they discovered that it is possible to provide an electrical storage device exterior material that suppresses curl during molding and has high mechanical strength compared to conventional electrical storage device exterior materials. Specifically, they discovered that by setting the total thickness of the laminate constituting the electrical storage device exterior material to 100 μm or less, setting the thickness of the base layer in the range of 18 μm to 22 μm, and setting the thickness of the barrier layer in the range of 27 μm to 38 μm, it is possible to obtain an electrical storage device exterior material that is thin, suppresses curl during molding, and has high mechanical strength.

The present disclosure has been completed based on these findings and further investigations. That is, the present disclosure provides the inventions of the following aspects.
The laminate is composed of at least a base layer, a barrier layer, and a heat-sealable resin layer in this order,
The thickness of the base layer is 18 μm or more and 22 μm or less,
the thickness of the barrier layer is 27 μm or more and 38 μm or less;
The laminate has a thickness of 100 μm or less.

The present disclosure makes it possible to provide an exterior material for an electricity storage device that, despite its thin thickness of 100 μm or less, is suppressed from curling during molding and has high mechanical strength. The present disclosure also makes it possible to provide a method for manufacturing an exterior material for an electricity storage device, and an electricity storage device.

1 is a schematic diagram showing an example of a cross-sectional structure of an exterior packaging material for an electricity storage device according to the present disclosure. 1 is a schematic diagram showing an example of a cross-sectional structure of an exterior packaging material for an electricity storage device according to the present disclosure. 1 is a schematic diagram showing an example of a cross-sectional structure of an exterior packaging material for an electricity storage device according to the present disclosure. 1 is a schematic diagram showing an example of a cross-sectional structure of an exterior packaging material for an electricity storage device according to the present disclosure. FIG. 2 is a schematic diagram illustrating a method for housing an electricity storage device element in a package formed from the exterior packaging material for an electricity storage device of the present disclosure. FIG. 2 is a schematic diagram illustrating a method for evaluating curling due to molding of an exterior material for an electricity storage device. FIG. 2 is a schematic diagram illustrating a method for evaluating curling due to molding of an exterior material for an electricity storage device.

The electrical storage device packaging material of the present disclosure is composed of a laminate having at least a substrate layer, a barrier layer, and a heat-sealable resin layer, in this order, and is characterized in that the substrate layer has a thickness of 18 μm or more and 22 μm or less, the barrier layer has a thickness of 27 μm or more and 38 μm or less, and the laminate has a thickness of 100 μm or less. By having this configuration, the electrical storage device packaging material of the present disclosure is able to suppress curling during molding, despite its thin thickness of 100 μm or less, and furthermore, has high mechanical strength.

The exterior packaging material for an electricity storage device disclosed herein is described in detail below. In this specification, numerical ranges indicated by "to" mean "greater than or equal to" or "less than or equal to." For example, the expression "2 to 15 mm" means 2 mm or greater and 15 mm or less. In this specification, the thickness of each layer constituting the laminate is rounded to one decimal place.

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

As shown in Figures 2 to 4, the exterior packaging material 10 for an electricity storage device may optionally include an adhesive layer 2 between the base layer 1 and the barrier layer 3 to enhance adhesion between these layers. As shown in Figures 3 and 4, the exterior packaging material 10 may optionally include an adhesive layer 5 between the barrier layer 3 and the heat-sealable resin layer 4 to enhance adhesion between these layers. As shown in Figure 4, a surface coating layer 6 may be provided on the outer side of the base layer 1 (the side opposite the heat-sealable resin layer 4) as needed. Specific examples of the laminate structure of the exterior material 10 for an electricity storage device include a laminate structure in which a substrate layer 1, a barrier layer 3, and a heat-sealable resin layer 4 are laminated in this order; a laminate structure in which a substrate layer 1, an adhesive layer 2, a barrier layer 3, and a heat-sealable resin layer 4 are laminated in this order; a laminate structure in which a substrate layer 1, a barrier layer 3, an adhesive layer 5, and a heat-sealable resin layer 4 are laminated in this order; a laminate structure in which a substrate layer 1, an adhesive layer 2, a barrier layer 3, an adhesive layer 5, and a heat-sealable resin layer 4 are laminated in this order; a laminate structure in which a surface coating layer 6, a substrate layer 1, a barrier layer 3, and a heat-sealable resin layer 4 are laminated in this order; a laminate structure in which a surface coating layer 6, a substrate layer 1, an adhesive layer 2, a barrier layer 3, and a heat-sealable resin layer 4 are laminated in this order; a laminate structure in which a surface coating layer 6, a substrate layer 1, a barrier layer 3, an adhesive layer 5 ... In a laminated structure in which the base layer 1 is the outermost layer, a lubricant may be present on at least one of the outer surface of the base layer 1 and the inner surface of the heat-sealable resin layer 4. In addition, in a laminated structure in which the surface coating layer 6 is the outermost layer, a lubricant may be present on at least one of the outer surface of the surface coating layer 6 and the inner surface of the heat-sealable resin layer 4. Lubricants will be described later.

The thickness of the laminate constituting the electrical storage device exterior material of the present disclosure is set to 100 μm or less. In the electrical storage device exterior material of the present disclosure, by setting the thickness of the laminate to 100 μm or less and setting the thicknesses of the substrate layer 1 and barrier layer 3 (described below) within specific ranges, curling during molding is suppressed and the electrical storage device exterior material has high mechanical strength, despite its thin thickness. From the viewpoints of optimally suppressing curling during molding and exhibiting high mechanical strength while making the electrical storage device exterior material as thin as possible, the thickness of the laminate is preferably about 75 μm or more, more preferably about 77 μm or more, even more preferably about 80 μm or more, even more preferably about 85 μm or more, and even 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, even more preferably about 93 μm or less, and even more preferably about 91 μm or less. Preferred ranges for 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 electrical storage device packaging material of the present disclosure, the ratio of the total thickness of the base material layer 1, optional adhesive layer 2, barrier layer 3, optional adhesive layer 5, heat-sealable resin layer 4, and optional surface coating layer 6 to the thickness (total thickness) of the laminate constituting the electrical storage device packaging material is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more. As a specific example, when the electrical storage device packaging material of the present disclosure includes the base material layer 1, adhesive layer 2, barrier layer 3, adhesive layer 5, and heat-sealable resin layer 4, the ratio of the total thickness of these layers to the thickness (total thickness) of the laminate constituting the electrical storage device packaging material 10 is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more. Furthermore, even when the electrical storage device packaging material of the present disclosure includes a substrate layer 1, an adhesive layer 2, a barrier layer 3, and a heat-sealable resin layer 4, the ratio of the total thickness of these layers to the thickness (total thickness) of the laminate constituting the electrical storage device packaging material 10 is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more.

In addition, in the packaging material for an electricity storage device disclosed herein, the total thickness of the layers located inside the barrier layer 3 (on the thermally adhesive resin layer 4 side) is preferably at least about 20 μm, more preferably at least about 22 μm, even more preferably at least about 24 μm, and even more preferably at least about 28 μm. Furthermore, this total thickness is preferably no more than about 40 μm, more preferably no more than about 38 μm, and even more preferably no more than about 35 μm. Preferred ranges for the total thickness include approximately 20 to 40 μm, approximately 20 to 38 μm, approximately 20 to 35 μm, approximately 22 to 40 μm, approximately 22 to 38 μm, approximately 22 to 35 μm, approximately 24 to 40 μm, approximately 24 to 38 μm, approximately 24 to 35 μm, approximately 28 to 40 μm, approximately 28 to 38 μm, and approximately 28 to 35 μm.

The thickness of each layer of the electrical storage device packaging material or the thickness of the laminate of the present disclosure can be measured by, for example, cutting the electrical storage device packaging material in the thickness direction using a microtome (REM-710 lithratome, manufactured by Yamato Koki Kogyo Co., Ltd.), dividing the electrical storage device packaging material into two, and observing the resulting cross section with, for example, a laser microscope (VK-9700, manufactured by Keyence Corporation).

In the case of the barrier layer 3 of the electrical storage device exterior packaging material, the MD (machine direction) and TD (transverse direction) during the manufacturing process can usually be determined. For example, if the barrier layer 3 is made of aluminum foil, linear streaks known as rolling marks are formed on the surface of the aluminum foil in the rolling direction (RD) of the aluminum foil. Because the rolling marks extend along the rolling direction, the rolling direction of the aluminum foil can be determined by observing the surface of the aluminum foil. Furthermore, during the manufacturing process of a laminate, the MD of the laminate usually coincides with the RD of the aluminum foil. Therefore, the MD of the laminate can be determined by observing the surface of the aluminum foil and identifying the rolling direction (RD) of the aluminum foil. Furthermore, because the TD of the laminate is perpendicular to the MD of the laminate, the TD of the laminate can also be determined.

The puncture strength from the outer surface side (substrate layer side or surface coating layer side) of the laminate constituting the electrical storage device exterior material is preferably 19 N or more, more preferably 23 N or more. The puncture strength is, for example, 30 N or less. The puncture strength is adjusted, for example, by the laminate structure of the electrical storage device exterior material, the thickness of the substrate layer 1, the stretch ratio during production of the substrate layer 1, the heat setting temperature, etc. The puncture strength is measured as follows.

<Puncture strength>
The puncture strength from the outer surface side (substrate layer side or surface coating layer side) of the laminate constituting the exterior material for an electricity storage device is measured by a method conforming to the provisions of JIS Z1707:1997. Measurement devices that can be used include, for example, Imada's ZP-50N (force gauge) and Imada's MX2-500N (measuring stand). In a measurement environment of 23±2°C and 50±5% relative humidity, a test specimen is fixed using a 115 mm diameter base with a 15 mm diameter opening in the center and a pressure plate, and a semicircular needle with a 1.0 mm diameter and a 0.5 mm tip radius is pierced at a rate of 50±5 mm per minute, and the maximum stress until the needle penetrates is measured. Ten test specimens are measured for each test, and the average value is calculated. If there are not enough test specimens to measure 10, the number of test specimens that can be measured is measured, and the average value is calculated. If the puncture strength is 19 N or more, the mechanical strength is sufficiently high, and if it is 23 N or more, the mechanical strength is particularly high.

The dynamic friction coefficient of the outer surface (the surface on the substrate layer side or the surface coating layer side) of the exterior material for an electric 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 dynamic friction coefficient is preferably about 0.80 or less, more preferably about 0.50 or less, and even more preferably about 0.25 or less. Preferred ranges for the dynamic friction coefficient include approximately 0.01 to 0.80, approximately 0.01 to 0.50, approximately 0.01 to 0.25, approximately 0.05 to 0.80, approximately 0.05 to 0.50, approximately 0.05 to 0.25, approximately 0.09 to 0.80, approximately 0.09 to 0.50, and approximately 0.09 to 0.25. The dynamic friction coefficient is adjusted by the material and lubricant of the layers that make up the outer surface of the exterior material for an electric storage device. The dynamic friction coefficient is measured as follows.

<Dynamic friction coefficient>
The dynamic friction coefficient is measured using a method conforming to JIS K7125:1999, Section 8.1, Film-to-Film Measurement. Two samples measuring 80 mm in the TD direction and 200 mm in the MD direction are cut out of the exterior material for a storage battery device. Next, the samples are stacked with their outer surfaces facing each other, and a slider is placed on top of them. Rubber is attached to the bottom of the slider, with a total mass of 200 g. The sample and slider are in close contact to prevent slippage. The slider is then pulled at a speed of 100 mm/min, and the dynamic friction force (N) between the two samples is measured. The dynamic friction force is divided by the normal force (1.96 N) of the slider to calculate the dynamic friction coefficient. The dynamic friction coefficient is determined from the average value for the first 30 mm after the start of relative shear movement between the contact surfaces, ignoring the peak of the static friction force. The load cell is directly connected to the slider.

Furthermore, when the electrical storage device packaging material of the present disclosure is subjected to the following four-fold test, it is preferable that it can be folded five or more times, and more preferably seven or more times, before a pinhole forms in the center. If it can be folded five or more times, it can be said that the mechanical strength of the electrical storage device packaging material is sufficiently high, and if it can be folded seven or more times, it can be said that the mechanical strength of the electrical storage device packaging material is particularly high.

<Four-fold test>
The exterior material for an electricity storage device is cut into strips measuring 150 mm in TD x 90 mm in MD, which serve as test samples. The test sample is folded in four 10 times, and the number of times until a pinhole forms in the center is measured. The test sample is folded in four by folding it in half at the center in the TD so that the short sides (sides in the MD) of the test sample overlap, and then folding it in half again at the center in the MD so that the sides in the TD overlap, resulting in a quarter-fold at the center of the test sample. This operation counts as one quarter-folding operation. The test sample is then unfolded, and the same quarter-folding and unfolding operations are repeated to perform the test. Five test samples are used for each test, and the average number of times until a pinhole forms in the center is calculated. If there are not enough test samples to measure five, the number of measurable samples is measured, and the average is calculated.

2. Layers forming the exterior material for an electricity storage device [Base layer 1]
In the present disclosure, the substrate layer 1 is a layer provided for the purpose of, for example, exhibiting the function as a substrate of the packaging material for an electricity storage device. The substrate layer 1 is located on the outer layer side of the packaging material for an electricity storage device. The substrate layer 1 may be the outermost layer (a layer constituting the outer surface), or, for example, in the case where a surface coating layer 6 described below is provided, the surface coating layer 6 may be the outermost layer (a layer constituting the outer surface).

One of the features of the electrical storage device packaging material disclosed herein is that the thickness of the substrate layer 1 is set to a specific range of 18 to 22 μm. From the perspective of optimally suppressing curling during molding and optimally exhibiting high mechanical strength despite the thin thickness of the electrical storage device packaging material, the thickness of the substrate layer 1 is preferably approximately 19 μm or greater. From the same perspective, the thickness of the substrate layer 1 is preferably approximately 21 μm or less. Preferred thickness ranges for the substrate layer 1 include approximately 18 to 21 μm, approximately 19 to 22 μm, and approximately 19 to 21 μm. Note that in the present disclosure, if the substrate layer 1 is composed of two or more layers and these layers are bonded together with an adhesive layer, such as an adhesive layer, the overall thickness of the substrate layer 1 does not include the thickness of the adhesive layer.

There are no particular restrictions on the material from which the substrate layer 1 is made, as long as it functions as a substrate, i.e., has at least insulating properties. The substrate layer 1 can be made, for example, using a resin, which may contain additives as described below.

When the base layer 1 is formed from a resin, the base layer 1 may be, for example, a resin film formed from a resin, or may be formed by applying a resin. The resin film may be an unstretched film or a stretched film. Stretched films include uniaxially stretched films and biaxially stretched films, with biaxially stretched films being preferred. Stretching methods for forming biaxially stretched films include, for example, sequential biaxial stretching, inflation, and simultaneous biaxial stretching. Methods for applying a resin include roll coating, gravure coating, and extrusion coating.

Examples of resins that form the base layer 1 include polyester, polyamide, polyolefin, epoxy resin, acrylic resin, fluororesin, polyurethane, silicone resin, and phenolic resin, as well as modified versions of these resins. The resin that forms the base layer 1 may also be a copolymer of these resins or a modified version of the copolymer. It may also be a mixture of these resins.

Of these, polyester and polyamide are preferred as resins for forming the base layer 1.

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

Specific examples of polyamides include aliphatic polyamides such as nylon 6, nylon 66, nylon 610, nylon 12, nylon 46, and copolymers of nylon 6 and nylon 66; hexamethylenediamine-isophthalic acid-terephthalic acid copolymer polyamides such as nylon 6I, nylon 6T, nylon 6IT, and nylon 6I6T (where I represents isophthalic acid and T represents terephthalic acid), which contain structural units derived from terephthalic acid and/or isophthalic acid; aromatic polyamides such as polyamide MXD6 (polymetaxylylene adipamide); alicyclic polyamides such as polyamide PACM6 (polybis(4-aminocyclohexyl)methane adipamide); polyamides copolymerized with lactam components or isocyanate components such as 4,4'-diphenylmethane diisocyanate; polyesteramide copolymers and polyetheresteramide copolymers, which are copolymers of copolymerized polyamides with polyesters or polyalkylene ether glycols; and other polyamide copolymers. These polyamides may be used alone or in combination of two or more.

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

The base layer 1 may be a single layer, or may be composed of two or more layers. When the base layer 1 is composed of two or more layers, the base layer 1 may be a laminate in which resin films are laminated with an adhesive or the like, or a laminate of resin films formed by co-extrusion of resins into two or more layers. Furthermore, a laminate of resin films formed by co-extrusion of resins into two or more layers may be used as the base layer 1 without being stretched, or may be uniaxially or biaxially stretched to form the base layer 1.

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

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

In order to effectively suppress curling during molding and to effectively exhibit high mechanical strength despite the thin thickness of the exterior material for an electricity storage device, it is preferable that the base material layer 1 be composed of a single layer of nylon film.

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

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

In addition, when the outer surface of the electrical storage device exterior material 10 is composed of the polyamide film of the base material layer 1, the crystallization index can be measured directly using the electrical storage device exterior material 10. Furthermore, when the outer surface of the electrical storage device exterior material 10 is not composed of the polyamide film of the base material layer 1, such as when the base material layer 1 has a multilayer structure as described above and a resin film other than the polyamide film (e.g., a polyester film) is positioned outside the polyamide film, or when the surface coating layer 6 described below is laminated on the outside of the base material layer 1, the layer positioned outside the polyamide film can be removed from the electrical storage device exterior material 10 to expose the surface of the polyamide film, and the crystallization index can be measured.

In the electrical storage device exterior packaging material 10, the crystallization index may be 1.50 or greater. However, from the viewpoint of favorably suppressing curling during molding and favorably exhibiting high mechanical strength despite the thin thickness of the electrical storage device exterior packaging material, the crystallization index is more preferably 1.55 or greater, even more preferably 1.60 or greater, even more preferably 1.65 or greater, and particularly preferably 1.69 or greater. The upper limit of the crystallization index is not particularly limited, but examples include 2.50 or less and 1.80 or less. Preferred ranges for the crystallization index include, for example, 1.50 to 2.50, 1.60 to 2.50, 1.65 to 2.50, 1.69 to 2.50, 1.50 to 1.80, 1.60 to 1.80, 1.65 to 1.80, and 1.69 to 1.80.

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

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

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

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

The lubricant present on the surface of the base layer 1 may be a lubricant exuded from the resin that constitutes the base layer 1, or a lubricant applied to the surface of the base layer 1. Furthermore, the lubricant present on the surface of the base layer 1 may be a lubricant that was present on the surface of the heat-sealable resin layer 4 and transferred to the surface of the base layer 1 when the electrical storage device packaging material was wound around a core or the like into a roll.

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

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

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

Examples of polyurethane adhesives include those containing a base agent containing a polyol compound and a curing agent containing an isocyanate compound. Two-component curing polyurethane adhesives are preferred, with a polyol such as polyester polyol, polyether polyol, or acrylic polyol as the base agent and an aromatic or aliphatic polyisocyanate as the curing agent. Furthermore, it is preferable to use a polyester polyol that has hydroxyl groups on the side chain in addition to the terminal hydroxyl groups of the repeating unit as the polyol compound. Examples of curing agents include aliphatic, alicyclic, aromatic, and araliphatic isocyanate compounds. Examples of isocyanate compounds include hexamethylene diisocyanate (HDI), xylylene diisocyanate (XDI), isophorone diisocyanate (IPDI), hydrogenated XDI (H6XDI), hydrogenated MDI (H12MDI), tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), and naphthalene diisocyanate (NDI). Also included are polyfunctional isocyanate-modified compounds of one or more of these diisocyanates. Multimers (e.g., trimers) can also be used as polyisocyanate compounds. Examples of such multimers include adducts, biurets, and nurates. Forming the adhesive layer 2 using a polyurethane adhesive provides the electrical storage device exterior material with excellent electrolyte resistance, preventing peeling of the base layer 1 even when the electrolyte adheres to the side surface.

In addition, other components may be added to the adhesive layer 2 as long as they do not impair adhesion, and may contain colorants, thermoplastic elastomers, tackifiers, fillers, etc. By including a colorant in the adhesive layer 2, the exterior material for an electrical storage device can be colored. Known colorants such as pigments and dyes can be used. Furthermore, only one type of colorant may be used, or two or more types may be mixed together.

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

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

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

The pigment content in the adhesive layer 2 is not particularly limited as long as it colors the exterior material for the energy storage device, and may be, for example, approximately 5 to 60% by mass, preferably 10 to 40% by mass.

The thickness of the adhesive layer 2 is not particularly limited as long as it can bond the base layer 1 and the barrier layer 3, but is, for example, approximately 1 μm or more, approximately 2 μm or more. The thickness of the adhesive layer 2 is, for example, approximately 10 μm or less, approximately 5 μm or less. Preferred thickness ranges for the adhesive layer 2 include approximately 1 to 10 μm, approximately 1 to 5 μm, approximately 2 to 10 μm, and approximately 2 to 5 μm.

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

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

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

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

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

From the viewpoint of improving the formability of the electrical storage device exterior material, the aluminum alloy foil is preferably a soft aluminum alloy foil made of, for example, an annealed aluminum alloy, and from the viewpoint of further improving formability, it is preferably an iron-containing aluminum alloy foil. In the iron-containing aluminum alloy foil (100% by mass), the iron content is preferably 0.1 to 9.0% by mass, and more preferably 0.5 to 2.0% by mass. By having an iron content of 0.1% by mass or more, an electrical storage device exterior material with better formability can be obtained. By having an iron content of 9.0% by mass or less, an electrical storage device exterior material with better flexibility can be obtained. Examples of soft aluminum alloy foils include aluminum alloy foils having a composition specified in JIS H4160:1994 A8021H-O, JIS H4160:1994 A8079H-O, JIS H4000:2014 A8021P-O, or JIS H4000:2014 A8079P-O. Silicon, magnesium, copper, manganese, etc. may be added as needed. Softening can be achieved by annealing or other methods.

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

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

One of the features of the electrical storage device packaging material disclosed herein is that the thickness of the barrier layer 3 is set to a specific range of 27 to 38 μm. From the perspective of favorably suppressing curling during molding and favorably exhibiting high mechanical strength despite the thin thickness of the electrical storage device packaging material, the thickness of the barrier layer 3 is preferably 28 μm or more, more preferably approximately 30 μm or more, and even more preferably 33 μm or more. From the same perspective, the thickness of the barrier layer is preferably 37 μm or less, more preferably 36 μm or less. Preferred ranges for the thickness of the barrier layer include approximately 27 to 37 μm, approximately 27 to 36 μm, approximately 28 to 38 μm, approximately 28 to 37 μm, approximately 28 to 36 μm, approximately 30 to 38 μm, approximately 30 to 37 μm, approximately 30 to 36 μm, approximately 33 to 38 μm, approximately 33 to 37 μm, and approximately 33 to 36 μm.

Furthermore, when the barrier layer 3 is a metal foil, it is preferable to provide a corrosion-resistant coating on at least the surface opposite the substrate layer to prevent dissolution and corrosion. The barrier layer 3 may also be provided with a corrosion-resistant coating on both sides. Here, a corrosion-resistant coating refers to a thin film formed on the surface of the barrier layer, which is provided with corrosion resistance (e.g., acid resistance, alkali resistance, etc.) by, for example, hydrothermal conversion treatment such as boehmite treatment, chemical conversion treatment, anodizing treatment, nickel or chromium plating treatment, or corrosion prevention treatment using a coating agent. Specifically, a corrosion-resistant coating refers to a coating that improves the acid resistance of the barrier layer (acid-resistant coating) or a coating that improves the alkali resistance of the barrier layer (alkali-resistant coating). The corrosion-resistant coating may be formed by one type of treatment or a combination of two or more types. Furthermore, a single layer or multiple layers can be formed. Furthermore, among these treatments, hydrothermal conversion treatment and anodizing treatment dissolve the metal foil surface with a treatment agent to form a metal compound with excellent corrosion resistance. These treatments may be included in the definition of chemical conversion treatment. In addition, when the barrier layer 3 is provided with a corrosion-resistant coating, the barrier layer 3 includes the corrosion-resistant coating.

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

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

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

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

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

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

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

The amount of the corrosion-resistant coating formed on the surface of the barrier layer 3 in the chemical conversion treatment is not particularly limited. For example, in the case of a paint-type chromate treatment, it is desirable that the barrier layer 3 contain, per square ^meter of its surface, about 0.5 to 50 mg, preferably about 1.0 to 40 mg, of a chromium-equivalent chromate compound, about 0.5 to 50 mg, preferably about 1.0 to 40 mg, of a phosphorus compound, and about 1.0 to 200 mg, preferably about 5.0 to 150 mg, of an aminated phenol polymer, in phosphorus-equivalent amounts.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

The thickness of the heat-sealable resin layer 4 can be set depending on the presence or absence of the adhesive layer 5 and the thickness of the adhesive layer 5, while setting the thickness of the laminate constituting the electrical storage device packaging material, the thickness of the base layer 1, and the thickness of the barrier layer 3 to the aforementioned predetermined thicknesses. The thickness of the heat-sealable 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, or about 15 μm or less. The thickness of the heat-sealable resin layer 4 is, for example, 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, or about 28 μm or more. Preferred ranges for the thickness of the heat-sealable resin layer 4 are 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, and about 28 to 30 μm.

In particular, when the thickness of adhesive layer 5 (described below) is within the range of 12 to 17 μm, the thickness of heat-sealable resin layer 4 is preferably approximately 17 μm or less, more preferably approximately 15 μm or less. Furthermore, when the thickness of adhesive layer 5 (described below) is within the range of 12 to 17 μm, the thickness of heat-sealable resin layer 4 is preferably approximately 8 μm or more, more preferably 10 μm or more. When the thickness of adhesive layer 5 (described below) is within the range of 12 to 17 μm, preferred thickness ranges for heat-sealable resin layer 4 include approximately 8 to 17 μm, approximately 8 to 15 μm, approximately 10 to 17 μm, and approximately 10 to 15 μm.

Furthermore, when the thickness of adhesive layer 5 described below is within the range of 1 to 5 μm, the thickness of heat-sealable resin layer 4 is preferably at least about 22 μm, more preferably at least about 25 μm, and even more preferably at least about 28 μm. Furthermore, when the thickness of adhesive layer 5 described below is within the range of 1 to 5 μm, the thickness of heat-sealable resin layer 4 is preferably no more than about 33 μm, more preferably no more than about 30 μm. When the thickness of adhesive layer 5 described below is within the range of 1 to 5 μm, the preferred thickness ranges of heat-sealable resin layer 4 are approximately 22 to 33 μm, approximately 22 to 30 μm, approximately 25 to 33 μm, approximately 25 to 30 μm, approximately 28 to 33 μm, and approximately 28 to 30 μm.

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

The adhesive layer 5 is formed from a resin capable of bonding the barrier layer 3 and the heat-sealable resin layer 4. Examples of resins used to form the adhesive layer 5 include the same adhesives as those exemplified for the adhesive layer 2. Furthermore, from the perspective of firmly bonding the adhesive layer 5 and the heat-sealable resin layer 4, the resin used to form the adhesive layer 5 preferably contains a polyolefin skeleton, such as the polyolefins and acid-modified polyolefins exemplified for the heat-sealable resin layer 4. On the other hand, from the perspective of firmly bonding the barrier layer 3 and the adhesive layer 5, the adhesive layer 5 preferably contains an acid-modified polyolefin. Examples of acid-modified components include dicarboxylic acids such as maleic acid, itaconic acid, succinic acid, and adipic acid, as well as their anhydrides, acrylic acid, and methacrylic acid. However, maleic anhydride is most preferred due to its ease of modification and versatility. Furthermore, from the perspective of the heat resistance of the electrical storage device exterior material, the olefin component is preferably a polypropylene-based resin, and the adhesive layer 5 most preferably contains maleic anhydride-modified polypropylene.

The inclusion of a polyolefin skeleton in the resin constituting the adhesive layer 5 can be determined by, for example, infrared spectroscopy, gas chromatography mass spectrometry, or the like; the analysis method is not particularly limited. Furthermore, the inclusion of an acid-modified polyolefin in the resin constituting the adhesive layer 5 can be determined, for example, by measuring a maleic anhydride-modified polyolefin by infrared spectroscopy, whereby peaks derived from maleic anhydride are detected at wavenumbers of approximately 1760 ^cm and 1780 ^cm . However, if the degree of acid modification is low, the peaks may be small and not be detected. In such cases, analysis can be performed by nuclear magnetic resonance spectroscopy.

Furthermore, from the perspective of ensuring durability, such as heat resistance and resistance to contents, of the electrical storage device exterior material, and ensuring formability while reducing the thickness, it is more preferable that the adhesive layer 5 be a cured product of a resin composition containing an acid-modified polyolefin and a curing agent. Preferred examples of acid-modified polyolefins include those listed above.

The adhesive layer 5 is preferably a cured product of a resin composition containing an acid-modified polyolefin and at least one compound selected from the group consisting of a compound having an isocyanate group, a compound having an oxazoline group, and a compound having an epoxy group. It is particularly preferably a cured product of a resin composition containing an acid-modified polyolefin and at least one compound selected from the group consisting of a compound having an isocyanate group and a compound having an epoxy group. The adhesive layer 5 preferably contains at least one compound selected from the group consisting of polyurethane, polyester, and epoxy resin, and more preferably contains polyurethane and epoxy resin. Preferred polyesters include, for example, ester resins formed by the reaction of epoxy groups with maleic anhydride groups, and amide ester resins formed by the reaction of oxazoline groups with maleic anhydride groups. If unreacted components of the curing agent, such as the compound having an isocyanate group, the compound having an oxazoline group, or the epoxy resin, remain in the adhesive layer 5, the presence of the unreacted components can be confirmed by a method selected from, for example, infrared spectroscopy, Raman spectroscopy, or time-of-flight secondary ion mass spectrometry (TOF-SIMS).

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

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

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

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

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

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

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

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

There are no particular restrictions on the polyurethane, and any known polyurethane can be used. The adhesive layer 5 may be, for example, a cured product of a two-component curing polyurethane.

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

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

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

The thickness of the adhesive layer 5 can be set according to the thickness of the heat-sealable resin layer 4, while setting the thickness of the laminate constituting the electrical storage device packaging material, the thickness of the base layer 1, and the thickness of the barrier layer 3 to the predetermined thicknesses. 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, or about 3 μm or less. 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, or about 15 μm or more. Preferred ranges for the thickness of the adhesive layer are, 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.

In particular, when the thickness of the aforementioned heat-sealable resin layer 4 is 8 to 17 μm, the thickness of the adhesive layer 5 is preferably at least about 12 μm, and more preferably at least about 15 μm. Furthermore, when the thickness of the heat-sealable resin layer 4 is 8 to 17 μm, the thickness of the adhesive layer 5 is preferably no more than about 17 μm, and more preferably no more than about 16 μm. Furthermore, when the thickness of the heat-sealable resin layer 4 is 8 to 17 μm, the preferred thickness ranges for the adhesive layer 5 are approximately 12 to 17 μm, approximately 12 to 16 μm, approximately 15 to 17 μm, and approximately 15 to 16 μm.

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

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

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

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

Examples of two-component curing polyurethanes include polyurethanes containing a base agent containing a polyol compound and a curing agent containing an isocyanate compound. Preferred examples include two-component curing polyurethanes that use a polyol such as polyester polyol, polyether polyol, or acrylic polyol as the base agent and an aromatic or aliphatic polyisocyanate as the curing agent. Furthermore, it is preferable to use a polyester polyol that has hydroxyl groups on the side chain in addition to the terminal hydroxyl groups of the repeating unit as the polyol compound. Examples of curing agents include aliphatic, alicyclic, aromatic, and araliphatic isocyanate compounds. Examples of isocyanate compounds include hexamethylene diisocyanate (HDI), xylylene diisocyanate (XDI), isophorone diisocyanate (IPDI), hydrogenated XDI (H6XDI), hydrogenated MDI (H12MDI), tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), and naphthalene diisocyanate (NDI). Also included are polyfunctional isocyanate-modified compounds of one or more of these diisocyanates. Furthermore, polymers (e.g., trimers) can also be used as polyisocyanate compounds. Examples of such polymers include adducts, biurets, and nurates. The aliphatic isocyanate compound refers to an isocyanate having an aliphatic group but not an aromatic ring, the alicyclic isocyanate compound refers to an isocyanate having an alicyclic hydrocarbon group, and the aromatic isocyanate compound refers to an isocyanate having an aromatic ring. The surface coating layer 6 is formed from polyurethane, which provides the electrical storage device packaging material with excellent electrolyte resistance.

The thickness of the surface coating layer 6 is not particularly limited as long as it exhibits the above-described functions as the surface coating layer 6 and the thicknesses of the laminate constituting the electrical storage device exterior material, the substrate layer 1, and the barrier layer 3 are all set to the aforementioned predetermined thicknesses. For example, the thickness of the surface coating layer 6 is approximately 0.1 μm or more, approximately 0.5 μm or more, approximately 1 μm or more, or approximately 2 μm or more. The thickness of the surface coating layer 6 is, for example, approximately 5 μm or less, approximately 4 μm or less, or approximately 3 μm or less. Preferred thickness ranges for the surface coating layer 6 include approximately 0.1 to 5 μm, approximately 0.1 to 4 μm, approximately 0.1 to 3 μm, approximately 0.5 to 5 μm, approximately 0.5 to 4 μm, approximately 0.5 to 3 μm, approximately 1 to 5 μm, approximately 1 to 4 μm, approximately 1 to 3 μm, approximately 2 to 5 μm, approximately 2 to 4 μm, and approximately 2 to 3 μm.

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

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

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

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

The lubricant present on the surface of the surface coating layer 6 may be a lubricant exuded from the resin that constitutes the base layer 1, or a lubricant applied to the surface of the base layer 1. Furthermore, the lubricant present on the surface of the surface coating layer 6 may be a lubricant that was present on the surface of the heat-fusible resin layer 4 and transferred to the surface of the surface coating layer 6 when the electrical storage device packaging material is wound around a core or the like into a roll.

3. Manufacturing Method of Electricity Storage Device Exterior Material The manufacturing method of the electricity storage device exterior material is not particularly limited as long as it can obtain a laminate in which each layer included in the electricity storage device exterior material of the present invention is laminated, and examples include a method including a step of laminating at least a substrate layer 1, a barrier layer 3, and a heat-sealable resin layer 4 in this order. That is, the manufacturing method of the electricity storage device exterior material of the present disclosure includes a step of laminating at least a substrate layer, a barrier layer, and a heat-sealable resin layer in this order to obtain a laminate, in which the thickness of the substrate layer is 18 μm or more and 22 μm or less, the thickness of the barrier layer is 27 μm or more and 38 μm or less, and the thickness of the laminate is 100 μm or less.

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

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

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

As described above, a laminate is formed which comprises, in this order, an optional surface coating layer 6, a substrate layer 1, an optional adhesive layer 2, a barrier layer 3, an optional adhesive layer 5, and a heat-sealable resin layer 4. In order to strengthen the adhesion of the optional adhesive layer 2 and adhesive layer 5, the laminate may be further subjected to a heat treatment.

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

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

Specifically, an electricity storage device using the electricity storage device packaging material of the present disclosure is provided by covering an electricity storage device element including at least a positive electrode, a negative electrode, and an electrolyte with the electricity storage device packaging material of the present disclosure, with metal terminals connected to the positive electrode and negative electrode protruding outward, so that a flange portion (a region where the heat-sealable resin layers contact each other) is formed around the periphery of the electricity storage device element, and the heat-sealable resin layers of the flange portion are heat-sealed to form a hermetic seal. When an electricity storage device element is housed in a package formed from the electricity storage device packaging material of the present disclosure, the package is formed so that the heat-sealable resin portion of the electricity storage device packaging material of the present disclosure faces inward (the surface that contacts the electricity storage device element). A package may be formed by overlapping two electrical storage device exterior materials with the heat-fusible resin layers facing each other and heat-sealing the peripheral portions of the overlapped electrical storage device exterior materials. Alternatively, as shown in the example of FIG. 5, one electrical storage device exterior material may be folded over and overlapped, and the peripheral portions may be heat-sealed to form a package. When folding over and overlapping, as shown in the example of FIG. 5, the edges other than the folded edge may be heat-sealed to form a package with a three-sided seal, or the material may be folded over to form a flange and sealed on all four sides. Furthermore, a recess for accommodating an electrical storage device element may be formed in the electrical storage device exterior material by deep drawing or bulging molding. As shown in the example of FIG. 5, one electrical storage device exterior material may have a recess and the other electrical storage device exterior material may not have a recess, or the other electrical storage device exterior material may also have a recess.

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

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

<Manufacturing of exterior materials for electricity storage devices>
Examples 1-8 and Comparative Examples 1-8
Each electrical storage device packaging material was manufactured by the following procedure, using the materials and thicknesses of each layer listed in Table 1. A biaxially oriented nylon film (Ny, thickness listed in Table 1) was prepared as a base layer, and aluminum foil (JIS H4160:1994 A8021H-O, thickness listed in Table 1) was prepared as a barrier layer with acid-resistant coatings formed on both sides. The biaxially oriented nylon film used in Example 1-8 had a crystallinity of 1.72, and the biaxially oriented nylon film used in Comparative Example 1-4 had a crystallinity of 1.68. The crystallinity was measured using a Nicolet iS10 (manufactured by Thermo Fisher Scientific Inc.) on the biaxially oriented nylon film laminated on the electrical storage device packaging material, using the method described above. Two types of aluminum foil obtained from different sources were used as the aluminum foil. The base layer and barrier layer were laminated by dry lamination. Specifically, a two-component curing urethane adhesive (a polyol compound and an aromatic isocyanate compound) was applied to one side of an aluminum foil having an acid-resistant coating formed on both sides, forming an adhesive layer (3 μm thick after curing) on the aluminum foil. Next, the adhesive layer on the aluminum foil and a biaxially oriented nylon film were laminated, and then aging treatment was performed to produce a substrate layer/adhesive layer/barrier layer laminate. In Examples 2 and 6, a two-component curing urethane adhesive (a black pigment, a polyol compound, and an aromatic isocyanate compound) containing a black pigment was used instead of the two-component curing urethane adhesive (a polyol compound and an aromatic isocyanate compound) used to bond the substrate layer and the barrier layer.

Next, in Examples 1, 3, 5, and 7 and Comparative Examples 1-8, maleic anhydride-modified polypropylene (PPa, thickness shown in Table 1) as an adhesive layer and polypropylene (PP, thickness shown in Table 1) as a heat-sealable resin layer were co-extruded onto the barrier layer of the resulting laminate, thereby laminating an adhesive layer/heat-sealable resin layer onto the barrier layer. The resulting laminate was then aged and heated to obtain an exterior packaging material for an electricity storage device (total thickness shown in Table 1) in which biaxially oriented nylon film/adhesive layer/barrier layer/adhesive layer/heat-sealable resin layer were laminated in this order.

In Examples 2 and 6, maleic anhydride-modified polypropylene (PPa, thickness listed in Table 1) as an adhesive layer and polypropylene (PP, thickness listed in Table 1) as a heat-sealable resin layer were co-extruded onto the barrier layer of the resulting laminate, thereby laminating an adhesive layer and a heat-sealable resin layer on the barrier layer. Furthermore, a resin composition (thickness after curing: 3 μm) containing silica as a filler additive with an average particle size of 1.5 μm, erucic acid amide, and a styrene-based resin with an average particle size of 2.5 μm was gravure-coated onto the surface of the biaxially oriented nylon film of the resulting laminate, forming a matte surface coating layer. This resulted in an exterior packaging material for an energy storage device (total thickness listed in Table 1) consisting of a surface coating layer/biaxially oriented nylon film/adhesive layer/barrier layer/adhesive layer/heat-sealable resin layer laminated in this order. The average particle size of the silica is the median diameter measured using a laser diffraction/scattering particle size distribution analyzer (Horiba, Ltd., "LA-950").

In Examples 4 and 8, a two-component curing adhesive (acid-modified polypropylene and epoxy compound) was applied to the barrier layer of a substrate layer/adhesive layer/barrier layer laminate, forming an adhesive layer (3 μm thick after curing) on aluminum foil. Furthermore, an unstretched polypropylene film (CPP, thickness listed in Table 1) was laminated onto the adhesive layer using the dry lamination method as a heat-sealable resin layer. The resulting laminate was then aged and heated to obtain an exterior packaging material for an electricity storage device (total thickness listed in Table 1) in which a biaxially oriented nylon film/adhesive layer/barrier layer/adhesive layer/heat-sealable resin layer was laminated in this order.

In addition, erucic acid amide was applied as a lubricant to the outer surface of the substrate layer of each of the exterior materials for electricity storage devices in Examples 1, 3-5, 7, and 8 and Comparative Examples 1-8.

<Dynamic friction coefficient of outer surface>
The dynamic friction coefficient of the outer surface (surface on the substrate layer side) of the electrical storage device exterior materials obtained in the Examples and Comparative Examples was measured as follows. The friction test was performed according to JIS K7125:1999, Section 8.1, Film-to-Film Measurement. First, two samples measuring 80 mm in the TD direction and 200 mm in the MD direction were cut out of each electrical storage device exterior material obtained above. Next, the samples were stacked with their outer surfaces facing each other, and a sliding piece was placed on top of them. Rubber was attached to the bottom of the sliding piece, and the total mass of the sliding piece was 200 g. The sample and the sliding piece were closely attached to each other to prevent slippage. Next, the sliding piece was pulled at a speed of 100 mm/min, and the dynamic friction force (N) between the two samples was measured. The dynamic friction force was divided by the normal force of the sliding piece (1.96 N) to calculate the dynamic friction coefficient. The dynamic friction coefficient was calculated from the average value over the first 30 mm after the start of relative shear movement between the contact surfaces, ignoring the peak static friction force. The load cell was directly connected to the slider. The results were evaluated according to the following criteria. The results are shown in Table 1.

<Evaluation of curl due to molding>
The resulting electrical storage device exterior material was cut into strips measuring 150 mm in transverse direction (TD) × 90 mm in machine direction (MD), which served as test samples. A 31.6 mm × 54.5 mm rectangular male mold (the surface had a maximum height roughness (nominal Rz value) of 1.6 μm, corner R2.0 mm, ridge R1.0 mm, as specified in Table 2 of the comparative surface roughness standard specimen in JIS B 0659-1:2002, Appendix 1 (Reference)) and a female mold with a clearance of 0.3 mm between the male mold and the female mold (the surface had a maximum height roughness (nominal Rz value) of 1.6 μm, corner R2.0 mm, ridge R1.0 mm, as specified in Table 2 of the comparative surface roughness standard specimen in JIS B 0659-1:2002, Appendix 1 (Reference)) were used. The maximum height roughness (nominal Rz value) of the comparative surface roughness standard piece, as specified in Table 2, is 3.2 μm. Using a mold having a corner R of 2.0 mm and a ridge R of 1.0 mm, the test sample was placed on a female mold so that the heat-sealable resin layer side was positioned on the male mold side, and the test sample was pressed with a pressure (surface pressure) of 0.25 MPa to obtain a size of 31.6 mm (MD) x 54.5 mm (TD) and a molding depth of 6 mm, and cold-molded (single-stage drawing molding). Details of the molding position are as shown in FIG. 6. As shown in FIG. 6, molding was performed at a position where the shortest distance d between the rectangular molding portion M and the end P of the exterior material 10 for an electricity storage device was 70.5 mm. The molding portion M indicates the position where a recess is formed by the mold. Next, the formed electrical storage device exterior material 10 was placed on a horizontal surface 20 as shown in FIG. 7, and the maximum distance t in the vertical direction y from the horizontal surface 20 to the end P was taken as the maximum height of the curled portion (the corner showing the maximum height among the four corners of the test sample). The smaller the value of the curl due to forming, the smaller the curl, and the more excellent the exterior material for an electrical storage device. The formed curl (mm) is the value obtained by rounding the maximum value t to one decimal place. The formed curl was evaluated according to the following criteria. The results are shown in Table 1.
A+: The curl during molding is 0 mm or more and less than 15 mm. The curl during molding is small, and does not substantially reduce productivity.
A: The curl during molding is 15 mm or more and less than 25 mm. The curl during molding is somewhat large, but the decrease in productivity is small.
B: The curl formed is 25 mm or more and less than 35 mm. The curl formed is large, and the productivity is greatly reduced.
C: The curl during molding is 35 mm or more. The curl during molding is very large, and the decrease in productivity is very large.

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

<Puncture strength>
The puncture strength from the outer surface side (substrate layer side or surface coating layer side) of the laminate constituting the exterior material for a power storage device was measured using an Imada ZP-50N (force gauge) and an Imada MX2-500N (measuring stand) in accordance with the provisions of JIS Z1707:1997. Specifically, in a measurement environment of 23±2°C and 50±5% relative humidity, a test specimen was fixed using a 115mm diameter base and a pressure plate with a 15mm diameter opening in the center, and a semicircular needle with a diameter of 1.0mm and a tip radius of 0.5mm was pierced at a rate of 50±5mm per minute, and the maximum stress until the needle penetrated was measured. Ten test specimens were used for each test, and the average value was calculated. Note that if there were not enough test specimens to measure 10, the number that could be measured was measured and the average value was calculated. The evaluation criteria are as follows.
A+: The puncture strength is 23N or more.
A: The puncture strength is 19N or more and less than 23N.
B: The puncture strength is 18N or more and less than 19N.
C: The puncture strength is less than 18N.

<Four-fold test>
The above-obtained exterior material for an electricity storage device was cut to prepare a strip of 150 mm TD (Transverse Direction) × 90 mm MD (Machine Direction), which was used as a test sample. The test sample was folded into four 10 times, and the number of times until a pinhole was formed in the center was measured. The folding operation was performed by folding the test sample in half so that the short sides (sides in the MD direction) of the test sample overlapped with each other at the center position in the TD direction so that the heat-sealable resin layers overlapped, and then folding it in half so that the sides in the TD direction overlapped with each other at the center position in the MD direction, and the operation of folding the center position of the test sample in four was performed, which was counted as one folding operation. The test sample was then opened in four, and the same folding operation and opening operation were repeated to perform the test. There were five test samples for each test, and the average number of times until a pinhole was formed in the center was calculated. If the number of test samples is insufficient to measure five samples, the number of samples that can be measured is measured and the average value is calculated. The evaluation criteria are as follows:
A+: Seven or more passes were required before a pinhole was formed in the center.
A: The number of times until a pinhole is formed in the center portion is 5 or more and 6 or less.
B: The number of times until a pinhole is formed in the center portion is 2 or more and 4 or less.
C: One cycle until a pinhole is formed in the center.

In Table 1, "ONy" refers to biaxially oriented nylon film, "urethane" refers to an adhesive layer formed using a two-component curing urethane adhesive using the dry lamination method, and "ALM A" and "ALM B" refer to aluminum foil, respectively.

As shown in Table 1, the electrical storage device packaging material of Example 1-8 is composed of a laminate having at least a base material layer, a barrier layer, and a heat-sealable resin layer in this order, with the thickness of the base material layer being 18 μm or more and 22 μm or less, the thickness of the barrier layer being 27 μm or more and 38 μm or less, and the thickness of the laminate being 100 μm or less. It can be seen that the electrical storage device packaging material of Example 1-8 is suppressed from curling during molding, despite its thin thickness of 100 μm or less, and furthermore, has high mechanical strength.

As described above, the present disclosure provides the following aspects of the invention.
Item 1. The laminate is composed of at least a base layer, a barrier layer, and a heat-sealable resin layer in this order,
The thickness of the base layer is 18 μm or more and 22 μm or less,
the thickness of the barrier layer is 27 μm or more and 38 μm or less;
The laminate has a thickness of 100 μm or less.
Item 2. An adhesive layer is provided between the barrier layer and the heat-sealable resin layer,
The thickness of the adhesive layer is 12 μm or more and 17 μm or less,
Item 2. The packaging material for an electricity storage device according to Item 1, wherein the heat-sealable resin layer has a thickness of 8 μm or more and 17 μm or less.
Item 3. An adhesive layer is provided between the barrier layer and the heat-sealable resin layer,
The thickness of the adhesive layer is 1 μm or more and 5 μm or less,
Item 2. The packaging material for an electricity storage device according to Item 1, wherein the heat-sealable resin layer has a thickness of 22 μm or more and 33 μm or less.
Item 4. The packaging material for an electricity storage device according to any one of Items 1 to 3, further comprising a surface coating layer on the side of the base material layer opposite to the barrier layer side.
Item 5. An electricity storage device, in which an electricity storage device element including at least a positive electrode, a negative electrode, and an electrolyte is housed in a package formed from the exterior packaging material for an electricity storage device according to any one of Items 1 to 4.
Item 6. The method includes a step of laminating at least a base layer, a barrier layer, and a heat-sealable resin layer in this order to obtain a laminate,
The thickness of the base layer is 18 μm or more and 22 μm or less,
the thickness of the barrier layer is 27 μm or more and 38 μm or less;
The method for producing an exterior material for an electricity storage device, wherein the laminate has a thickness of 100 μm or less.

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

Claims (24)

The laminate is composed of at least a base layer, an adhesive layer, a barrier layer, an adhesive layer, and a heat-sealable resin layer in this order,
the substrate layer includes a stretched polyamide film,
The thickness of the base layer is 18 μm or more and 22 μm or less,
the adhesive layer is formed of a polyurethane adhesive;
The thickness of the adhesive layer is 1 μm or more and 10 μm or less,
the barrier layer comprises an aluminum alloy foil;
the thickness of the barrier layer is 27 μm or more and 38 μm or less;
the adhesive layer comprises a polyolefin;
the heat-sealable resin layer contains polyolefin,
a total thickness of the layers located closer to the thermal adhesive resin layer than the barrier layer is 20 μm or more and 40 μm or less;
The laminate has a thickness of 100 μm or less. The thickness of the adhesive layer is 12 μm or more and 17 μm or less,
The packaging material for an electricity storage device according to claim 1 , wherein the thermally adhesive resin layer has a thickness of 8 μm or more and 17 μm or less. The thickness of the adhesive layer is 1 μm or more and 5 μm or less,
The packaging material for an electricity storage device according to claim 1 , wherein the thermally adhesive resin layer has a thickness of 22 μm or more and 33 μm or less. The exterior packaging material for an electricity storage device according to any one of claims 1 to 3, further comprising a surface coating layer on the side of the substrate layer opposite the barrier layer. The exterior material for an electricity storage device according to any one of claims 1 to 4, wherein two or more types of lubricants are present on at least one of the surface and interior of the base material layer. The exterior material for an electricity storage device according to any one of claims 1 to 5, wherein at least two selected from the group consisting of 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 are present on at least one of the surface and interior of the base layer. a lubricant is present on the surface of the substrate layer;
The exterior packaging material for an electricity storage device according to any one of claims 1 to 6, wherein the lubricant is present in an amount of 3 mg/m2 or ^more . a lubricant is present on the surface of the heat-sealable resin layer;
The exterior packaging material for an electricity storage device according to any one of claims 1 to 7, wherein the lubricant is present in an amount of 10 mg/m2 or ^more . The exterior packaging material for an electricity storage device according to any one of claims 1 to 8, wherein the heat-sealable resin layer is composed of a resin containing a polyolefin skeleton. The electrical storage device packaging material according to any one of claims 1 to 9, wherein the heat-sealable resin layer contains at least one selected from the group consisting of polyolefins, cyclic polyolefins, acid-modified polyolefins, and acid-modified cyclic polyolefins. The exterior packaging material for an electricity storage device according to any one of claims 1 to 10, wherein the heat-sealable resin layer is formed from a blend polymer that combines two or more types of resin. The packaging material for an electricity storage device according to any one of claims 1 to 11, wherein the heat-sealable resin layer is formed of two or more layers of the same or different resins. The packaging material for an electricity storage device according to any one of claims 1 to 12, wherein two or more types of lubricants are present on at least one of the surface and interior of the heat-sealable resin layer. The electrical storage device packaging material according to any one of claims 1 to 13, wherein at least two selected from the group consisting of 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 are present on at least one of the surface and interior of the heat-sealable resin layer. The packaging material for an electricity storage device according to any one of claims 1 to 14, wherein the adhesive layer is made of a resin containing a polyolefin skeleton. The adhesive layer comprises at least one selected from the group consisting of polyolefins, cyclic polyolefins, acid-modified polyolefins, and acid-modified cyclic polyolefins. An outer casing material for an electricity storage device according to any one of claims 1 to 15. The packaging material for an electricity storage device according to any one of claims 1 to 16, wherein the adhesive layer is formed from a blend polymer in which two or more types of resins are combined. a surface coating layer on the opposite side of the substrate layer from the barrier layer side,
The packaging material for an electricity storage device according to any one of claims 1 to 17, wherein a lubricant is present on at least one of the surface and the interior of the surface coating layer. a surface coating layer on the opposite side of the substrate layer from the barrier layer side,
The packaging material for an electricity storage device according to any one of claims 1 to 18, wherein two or more types of lubricants are present on at least one of the surface and the interior of the surface coating layer. a surface coating layer on the opposite side of the substrate layer from the barrier layer side,
The exterior material for a storage battery device according to any one of claims 1 to 19, wherein at least one selected from the group consisting of 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 is present on at least one of the surface and the interior of the surface coating layer. An electricity storage device in which an electricity storage device element having at least a positive electrode, a negative electrode, and an electrolyte is housed in a package formed from the exterior packaging material for an electricity storage device according to any one of claims 1 to 20. The method includes a step of laminating at least a base layer, an adhesive layer, a barrier layer, an adhesive layer, and a heat-sealable resin layer in this order to obtain a laminate,
the substrate layer includes a stretched polyamide film,
The thickness of the base layer is 18 μm or more and 22 μm or less,
the adhesive layer is formed of a polyurethane adhesive;
The thickness of the adhesive layer is 1 μm or more and 10 μm or less,
the barrier layer comprises an aluminum alloy foil;
the thickness of the barrier layer is 27 μm or more and 38 μm or less;
the adhesive layer comprises a polyolefin;
the heat-sealable resin layer contains polyolefin,
a total thickness of the layers located closer to the thermal adhesive resin layer than the barrier layer is 20 μm or more and 40 μm or less;
The method for producing an exterior material for an electricity storage device, wherein the laminate has a thickness of 100 μm or less. 23. The method for producing an exterior material for an electricity storage device according to claim 22 , wherein the adhesive layer and the heat-sealable resin layer are formed by a co-extrusion lamination method, a tandem lamination method, a thermal lamination method, a sandwich lamination method, or a method of solution-coating an adhesive for forming the adhesive layer onto the barrier layer, and laminating the heat-sealable resin layer, which has been formed in advance into a sheet shape, onto the adhesive layer. The method for producing an exterior packaging material for an electricity storage device according to claim 22 or 23, wherein the heat-sealable resin layer is formed of two or more layers made of the same or different resins.