TW201616705A - Packaging material for power storage device and power storage device - Google Patents

Abstract

The present invention relates to a packaging material 1 for a power storage device, which is characterized in comprising: a heat-resistant resin layer 2 used as an outer layer, a thermoplastic resin layer 3 used as an inner layer, and a metal foil layer 4 arranged between the two layers. A center line average roughness (Ra) of a surface 4a on the outer layer 2 side of the metal foil is from 1nm to 150nm. According to the present invention, a packaging material for a power storage device having excellent malleability even when performing deep molding is provided.

Description

External storage material and power storage device for power storage device

The present invention relates to a battery or a power source used in a portable device such as a smart phone or a tablet computer, and a power storage device such as a battery or a power source used for power storage of a hybrid vehicle, an electric vehicle, a wind power generation, a solar power generation, and a nighttime generator. The exterior material and the power storage device externally mounted on the exterior material.

In addition, the "center line average roughness" described in the patent application scope and the specification of the present application refers to the center line average roughness Ra measured based on JIS B0601-2001.

In recent years, it has become thinner and lighter in portable devices such as smart phones and tablet terminals, and is used as a power storage device such as a lithium ion battery, a lithium polymer battery, a lithium ion capacitor, or an electric double layer capacitor mounted on such devices. In the outer casing, a heat-resistant resin layer/adhesive layer/metal foil layer/adhesive layer/thermoplastic resin layer is used to replace the conventional metal can (refer to Patent Document 1). Usually, the laminated body is subjected to inflation molding or deep drawing molding to form a three-dimensional shape such as a substantially rectangular parallelepiped shape. In addition, in the case of a power source for an electric vehicle or the like, a large-sized power source for power storage, a capacitor, and the like, the laminate (the exterior material) having the above-described configuration is used, and the number of the exterior is gradually increased.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2007-161310

The battery for carrying equipment, etc., is expected to increase the battery capacity, but increasing the battery capacity requires further increase in the volume of the contents. In the case of increasing the volume of the contents of the battery, deep forming is required when the exterior material is formed into a three-dimensional shape, but such deep forming is required, and the outer material needs to have good formability to prevent the corner portion of the molded article. Such as pinholes or cracks.

In addition, batteries for electric vehicles and the like must be long-lived, so the exterior materials are also expected to be long-lived. In the exterior material for batteries, the adhesion strength between the metal foil layer and the thermoplastic resin layer (inner layer) is lowered with time due to the influence of the electrolyte or the like of the contents, so the current positive electrode force Seek to maintain this tightness for a long time.

In view of the above-described technical background, the first object of the present invention is to provide an exterior material for a power storage device which can ensure excellent formability even when deep molding is performed.

To achieve the foregoing objects, the present invention provides the following means.

1) An exterior material for a power storage device, characterized in that it contains heat resistance as an outer layer The resin layer, the thermoplastic resin layer as the inner layer, and the metal foil layer disposed between the two layers; and the center line average roughness (Ra) of the surface on the outer layer side of the metal foil is 1 nm to 150 nm.

(2) The exterior material for a storage battery device according to the above aspect, wherein a center line average roughness (Ra) of the surface on the inner layer side of the metal foil is 100 nm to 500 nm.

(3) A power storage device, comprising: a power storage device main body portion, and an external storage material for a power storage device according to the above item 1 or 2; and the power storage device main body portion is externally mounted by the exterior material .

According to the invention of [1], since the center line average roughness (Ra) of the surface on the side layer side of the metal foil layer is from 1 nm to 150 nm, even if the exterior material is subjected to deep molding, the metal foil layer can be sufficiently prevented. The "peeling between the metal foil layer and the outer layer (heat resistant resin layer) at the time of molding" caused by the surface roughness. In other words, even when the exterior material is subjected to deep molding, excellent moldability can be ensured, and the adhesion between the metal foil layer and the outer layer (heat resistant resin layer) can be sufficiently maintained during molding. That is, the above first object can be achieved. Further, since the center line average roughness (Ra) of the surface on the side layer side of the metal foil layer is from 1 nm to 150 nm, when the exterior material of the present invention is visually observed from the outside, the appearance thereof has a metallic luster.

According to the invention of [2], the center line average roughness (Ra) of the surface on the inner layer side of the metal foil layer is from 100 nm to 500 nm, and the surface unevenness of the surface on the inner layer side of the metal foil can be used for the adhesive layer. The anchoring effect is fully exerted, such as the metal foil layer and the inner layer (heat The adhesive strength between the plastic resin layers) can sufficiently ensure the initial strength while maintaining a sufficient bonding strength for a long period of time. That is, the above second object can be achieved. For example, even if the content of the electrical storage device has an electrolytic solution or the like, the adhesion strength between the metal foil layer and the thermoplastic resin layer (inner layer) does not decrease with time, and sufficient adhesion strength can be maintained over a long period of time.

According to the invention (the power storage device) of the above [3], it is possible to provide a power storage device, and even if the volume of the content is designed to be large in order to increase the capacity of the power storage device, it is possible to form a deep shape without cracks. The exterior material is externally mounted and has a metallic luster.

1‧‧‧External materials for power storage devices

2‧‧‧Heat resistant resin layer (outer layer)

3‧‧‧ thermoplastic resin layer (inner layer)

4‧‧‧metal foil layer

4a‧‧‧Face on the outer side of the metal foil

4b‧‧‧ the side of the inner side of the metal foil

5‧‧‧1st adhesive layer

6‧‧‧2nd adhesive layer

11‧‧‧Shaped housing

19‧‧‧Power storage unit body

20‧‧‧Power storage device

Fig. 1 is a cross-sectional view showing an embodiment of an exterior material for a storage battery device according to the present invention.

Fig. 2 is a cross-sectional view showing an embodiment of a power storage device comprising an exterior material for a power storage device according to the present invention.

An embodiment of the exterior material 1 for a storage battery device according to the present invention is shown in Fig. 1 . The exterior material 1 for a storage device is used as a lithium ion secondary battery case. In other words, the exterior material 1 for an electrical storage device is used as a casing user of a secondary battery by performing molding such as deep drawing molding or bulging molding.

In the exterior material 1 for a power storage device, the surface of one side of the metal foil layer 4 is integrated with the heat-resistant resin layer (outer layer) 2 by the first adhesive layer 5, and the metal foil layer 4 is laminated. The other side passes through the second adhesive layer 6 and the thermoplastic resin layer (inside Layer) 3 layers formed by integration.

In the present invention, the metal foil layer 4 is a metal foil having a center line average roughness (Ra) of 1 nm to 150 nm on the outer layer side surface 4a. If Ra is less than 1 nm, the rolling cost of the foil will be higher. On the other hand, when Ra exceeds 150 nm and the exterior material is subjected to deep molding, peeling occurs between the metal foil layer 4 and the outer layer (heat resistant resin layer) 2 during molding. If such a portion between the metal foil layer 4 and the outer layer 2 is peeled off during the forming, stress concentration occurs and the metal foil layer 4 shrinks and deforms, and most of the results cause cracking during molding.

The center line average roughness (Ra) of the surface 4a on the outer layer side of the metal foil 4 is preferably 5 nm to 100 nm, and Ra is preferably 5 nm to 40 nm.

In addition, as the metal foil 4, a metal foil having a center line average roughness (Ra) of 1 nm to 150 nm on the outer layer side surface 4a is used to constitute the outer casing 1 of the present invention, and the outer casing 1 is outside. The total value (index value of glossiness) measured on the side of layer 2 (from the upper side of FIG. 1) is in the range of 200 to 800, and when the exterior material 1 of the present invention is visually observed from the outer layer side, the appearance is Has a metallic luster. There is a relationship that the smaller the center line average roughness (Ra) of the surface 4a on the outer layer side is, the larger the total value is.

In the present invention, as the metal foil 4, a metal foil having a center line average roughness (Ra) of 100 nm to 500 nm on the inner layer side surface 4b is preferably used. When the Ra of the surface 4b on the inner layer side is 100 nm or more, the anchoring effect of the second adhesive layer 6 can be sufficiently exhibited, and the bonding strength between the metal foil layer 4 and the inner layer (thermoplastic resin layer) 3 can be sufficiently ensured. Its initial strength, while maintaining a sufficient bonding strength for a long time. Further, when the Ra of the surface 4b on the inner layer side is 500 nm or less, the adhesive can be applied evenly.

Among them, the center line average thickness (Ra) of the surface 4b on the inner layer side of the metal foil 4 is preferably from 140 nm to 350 nm.

The heat-resistant resin constituting the heat-resistant resin layer (outer layer) 2 is a heat-resistant resin that does not melt at the heat sealing temperature when the exterior material is heat-sealed. The heat resistant resin is preferably a heat resistant resin having a melting point higher than a melting point of the thermoplastic resin constituting the thermoplastic resin layer 3 by 10 ° C or more, and the melting point is higher than the melting point of the thermoplastic resin by 20 ° C or more. The heat resistant resin is particularly excellent.

The heat-resistant resin layer (outer layer) 2 is not particularly limited, and examples thereof include a polyamide film such as a nylon film, a polyester film, and the like, and such a stretched film can be preferably used. In the heat-resistant resin layer 2, a biaxially stretched polyamide film such as a biaxially stretched nylon film, a biaxially stretched polybutylene terephthalate (PBT) film, and a biaxially oriented polyterephthalic acid are used. A glycol ester (PET) film or a biaxially stretched polyphthalic acid (PEN) film is particularly preferred. The nylon film is not particularly limited, and examples thereof include a nylon film, a 6,6 nylon film, and an MXD nylon film. Further, the heat-resistant resin layer 2 may be formed of a single layer, or may be formed of, for example, a plurality of layers (a plurality of layers of a PET ester film/nylon film) composed of a polyester film/polyamide film.

The thickness of the heat resistant resin layer 2 is preferably from 12 μm to 50 μm. When a polyester film is used, the thickness is preferably from 12 μm to 50, and when a nylon film is used, the thickness is preferably from 15 μm to 50 μm. By setting it at or above the above preferred lower limit value, it is possible to ensure sufficient strength of the packaging material, and by setting it below the above preferred upper limit value, it is possible to reduce stress during bulging forming or deep drawing forming. Formability.

The aforementioned thermoplastic resin layer (inner layer) 3, even for use in lithium ionization An electrolyte solution having a high corrosiveness such as a sub-battery or the like has excellent chemical resistance and is also responsible for imparting heat sealing properties to the packaging material.

The thermoplastic resin layer 3 is not particularly limited, but is preferably a thermoplastic film unstretched film layer. The thermoplastic resin unstretched film layer 3 is not particularly limited, and is preferably at least one selected from the group consisting of polyethylene, polypropylene, an olefin-based copolymer, an acid-modified product thereof, and an ionic polymer. A non-stretched film composed of a plastic resin is preferably used.

The thickness of the thermoplastic resin layer 3 is preferably set to 20 μm to 80 μm. By setting it at 20 μm or more, the occurrence of pinholes can be sufficiently prevented, and by setting it to 80 μm or less, the amount of the resin can be lowered to achieve cost reduction. Among them, it is particularly preferable that the thickness of the thermoplastic resin layer 3 is set to 30 μm to 50 μm. Further, the thermoplastic resin layer 3 may be a single layer or a plurality of layers.

The metal foil layer 4 is responsible for imparting gas barrier properties to the outer packaging material 1 to prevent oxygen or moisture from entering. The metal foil layer 4 is not particularly limited, and examples thereof include an aluminum foil and a copper foil, and aluminum foil is generally used. The thickness of the metal foil layer 4 is preferably 20 μm to 100 μm. When the thickness is 20 μm or more, the production of the metal foil can prevent the occurrence of the pinhole which is delayed, and at the same time, when the thickness is 100 μm or less, the stress at the time of inflation molding or deep drawing can be lowered to improve the formability.

It is preferable that the metal foil layer 4 is subjected to a chemical conversion treatment at least on the inner surface 4b (the surface on the second adhesive layer 6 side). By performing such a chemical conversion treatment, the surface corrosion of the metal foil due to the contents (electrolyte of the battery, etc.) can be sufficiently prevented. In addition, when the chemical conversion treatment film is formed on the surface 4a (the surface on the side of the first adhesive layer 5) on the side layer side of the metal foil, the following effects can be obtained. That is, there is a very small amount of oxygen and liquid from the heat resistant resin layer (outer layer) Inflow of doubts, if these intrusions reach the metal foil layer, it may become the cause of corrosion of the metal foil layer. At this time, there will be a decrease in the metallic luster of the metal foil layer or a local turbidity, by the outside of the metal foil. A chemical conversion treatment film is formed on the surface of the layer side, and these problems can be sufficiently prevented. Further, when the electrolytic solution is injected, even if the electrolytic solution adheres to the outer layer or the end surface of the opening for liquid injection, it is possible to sufficiently prevent corrosion of the metal foil layer by forming a chemical conversion treatment film on the side of the side layer side of the metal foil. . For example, the chemical conversion treatment of the metal foil can be performed by performing the treatment described below. In other words, for example, an aqueous solution of any one of the following 1) to 3) can be applied to the surface of the metal foil after the degreasing treatment, and then dried to carry out a chemical conversion treatment.

1) an aqueous solution containing a mixture of at least one compound selected from the group consisting of a metal salt of phosphoric acid, chromic acid, a fluoride, and a non-metal salt of a fluoride

2) a resin containing at least one of a group consisting of phosphoric acid, an acrylic resin, a chitosan derivative resin, and a phenol resin, and at least one selected from the group consisting of chromic acid and chromium (III) salt An aqueous solution of a mixture of one compound

3) a resin containing at least one selected from the group consisting of phosphoric acid, an acrylic resin, a chitosan derivative resin, and a phenol resin, and at least one selected from the group consisting of chromic acid and chromium (III) salt. At least one of a compound, a metal salt selected from a fluoride, and a non-metal salt of a fluoride An aqueous solution of a mixture of the compounds.

The chemical conversion film has a chromium adhesion amount (each side) of preferably 0.1 mg/m ² to 50 mg/m ^{2 , and particularly} preferably 2 mg/m ² to 20 mg/m ² .

The first adhesive layer 5 is not particularly limited, and examples thereof include a polyurethane adhesive layer, a polyester urethane adhesive layer, and a polyether urethane adhesive layer. The thickness of the first adhesive layer 5 is preferably set to 1 μm to 5 μm. In particular, the thickness of the first adhesive layer 5 is preferably 1 μm to 3 μm from the viewpoint of thinning and weight reduction of the exterior material.

Although the second adhesive layer 6 is not particularly limited, for example, the above-described first adhesive layer 5 can be used, but a polyolefin-based adhesive which is less likely to swell by the electrolytic solution is preferably used. The thickness of the second adhesive layer 6 is preferably set to 1 μm to 5 μm. In particular, the thickness of the second adhesive layer 6 is particularly preferably 1 μm to 3 μm from the viewpoint of thinning and weight reduction of the exterior material.

The outer casing 1 of the present invention can be obtained by molding (deep drawing, bulging molding, etc.) to obtain a molded casing (battery casing or the like). Further, the exterior material 1 of the present invention may be used as it is without being molded.

One embodiment of the battery device 20 constructed using the exterior material 1 of the present invention is shown in FIG. This battery device 20 is a lithium ion secondary battery.

The battery 20 includes an electrolyte 21, a tab 22, the outer casing 1 that is not formed into a flat shape, and the outer casing 1 that is molded to obtain a molded casing 11 having a housing recess 11b (see FIG. 2). ). The power storage device main body portion 19 is configured by the electrolyte 21 and the tab 22 described above.

A part of the electrolyte 21 and the tab 22 are accommodated in the housing recess 11b of the molded case 11, and the planar outer casing 1 is placed on the molded casing 11 by the peripheral portion of the outer casing 1 ( The inner layer 3) is joined to the sealing inner peripheral portion 11a (the inner layer 3) of the molded casing 11 and sealed to constitute the battery 20. Further, the tip end portion of the tab 22 is led out (see Fig. 2).

[Examples]

Next, specific examples of the invention will be described, but the invention is not particularly limited to the examples.

<Example 1>

The center line average roughness Ra of the one side is 40 nm, the center line average roughness Ra of the other side is 30 nm, and both sides of the aluminum foil 4 having a thickness of 35 μm are coated with polyacrylic acid, a trivalent chromium compound, The chemical conversion treatment liquid formed of water or alcohol was dried at 180 ° C to form a chemical conversion film. The chromium adhesion amount of the chemical conversion film was 10 mg/m ^{2 on} one side.

Next, on the surface on one side of the aluminum foil 4 (the surface having a Ra of 40 nm), the two-liquid-curing type urethane-based adhesive 5 and the two-axis-stretched nylon film having a thickness of 15 μm (melting point: 220 ° C) 2) Dry lamination (fitting).

Next, a maleic acid-denatured polypropylene layer (second adhesive layer) 6 having a thickness of 7 μm and an ethylene having a melting point of 140 ° C and an MFR (melt flow rate) of 7 g/10 minutes and a thickness of 28 μm were used by using a T-die. - a propylene random copolymer resin layer (inner layer) 3 is co-extruded, and a laminate film obtained by laminating these two layers is obtained, and immediately after the total extrusion, the second adhesive layer of the laminated film is formed on the surface of the second adhesive layer. The surface of the other side of the aluminum foil 4 after the dry lamination (Ra 230 The surface of the nm 4b is superposed, and is thermally laminated by using a pair of hot rollers heated to 150 ° C to obtain an exterior material 1 for a storage device having the configuration shown in FIG. 1 .

<Example 2>

In addition to the aluminum foil 4, the center line average roughness Ra of the one side surface (the outer layer side surface) 4a is 10 nm, and the center line average roughness Ra of the other side surface (the inner layer side surface) 4b is 140 nm. In the same manner as in the first embodiment, the aluminum foil having a thickness of 35 μm was obtained, and the exterior material 1 for a power storage device having the configuration shown in Fig. 1 was obtained.

<Example 3>

In addition to the aluminum foil 4, the center line average roughness Ra of the surface on the one side (the surface on the outer layer side) 4a is 70 nm, and the center line average roughness Ra of the surface on the other side (the surface on the inner layer side) 4b is 450 nm. In the same manner as in the first embodiment, the aluminum foil having a thickness of 35 μm was obtained, and the exterior material 1 for a power storage device having the configuration shown in Fig. 1 was obtained.

<Example 4>

In addition to the aluminum foil 4, the center line average roughness Ra of the one side surface (the outer layer side surface) 4a is 40 nm, and the center line average roughness Ra of the other side surface (the inner layer side surface) 4b is 500 nm. In the same manner as in the first embodiment, the aluminum foil having a thickness of 35 μm was obtained, and the exterior material 1 for a power storage device having the configuration shown in Fig. 1 was obtained.

<Example 5>

In addition to the aluminum foil 4, the center line average roughness Ra of the surface on the one side (the surface on the outer layer side) 4a is 5 nm, and the center line average roughness Ra of the surface on the other side (the surface on the inner layer side) 4b is 230 nm. In the same manner as in the first embodiment, the aluminum foil having a thickness of 35 μm was obtained, and the exterior material 1 for a power storage device having the configuration shown in Fig. 1 was obtained.

<Example 6>

In addition to the aluminum foil 4, the center line average roughness Ra of the one side surface (the outer layer side surface) 4a is 110 nm, and the center line average roughness Ra of the other side surface (the inner layer side surface) 4b is 70 nm. In the same manner as in Example 1, except for the aluminum foil having a thickness of 35 μm, an exterior material for a storage battery device was obtained.

<Comparative Example 1>

In addition to the aluminum foil 4, the center line average roughness Ra of the surface on the one side (the surface on the outer layer side) 4a is 230 nm, and the center line average roughness Ra of the surface on the other side (the surface on the inner layer side) 4b is 40 nm. In the same manner as in Example 1, except for the aluminum foil having a thickness of 35 μm, an exterior material for a storage battery device was obtained.

In addition, the center line average roughness Ra of the surface of the aluminum foil used in each of the above-mentioned examples and the comparative examples was measured by JIS B0601-2001 using the surface roughness measuring machine "SURFTEST SV600" manufactured by Mitutoyo Corporation. The value.

Further, the adjustment of the individual Ra of both surfaces of the respective aluminum foils used in the respective examples and the comparative examples was carried out as follows. Examples 2, 3, 4, and 6 were used for the prepared aluminum foil having a thickness of 300 μm. The calendering roller above and below the calender is calendered several times until its thickness reaches a predetermined thickness, by changing the surface roughness of the final calendering roller to a different one (by using the surface roughness as the final calendering roller) And adjust Ra. On the other hand, in the first, fifth, and comparative examples, two sheets of aluminum foil having a thickness of 300 μm were prepared, and rolling was performed several times using a rolling roller above and below the foil calender until the thickness reached a predetermined thickness. The surface roughness of the final calender roll is changed to a different one (by using the surface roughness as the final calender roll), the Ra of the surface of the contact calender roll is adjusted. whole. In the latter case, the Ra of the surface of the two aluminum foils was 230 nm.

The external materials for electrical storage devices obtained as described above were evaluated for performance based on the following evaluation method. The results are shown in Table 1.

<Formability Evaluation Method>

The outer casing was bulged in a slightly rectangular shape of 55 mm in length × 35 mm in width by an inflation molding machine (No. TP-25C-X2) manufactured by Amada Co., Ltd., that is, the forming of the forming depth was changed, and observation was carried out. Whether or not pinholes and cracks were formed in the corner portions of the obtained molded body, the "maximum forming depth (mm)" at which pinholes and cracks were not generated was measured.

<Electrolyte resistance evaluation method>

The outer packaging material was cut into a test piece of a width of 15 mm, and the mixture was dissolved in a mixed solvent of ethylene carbonate and diethyl carbonate at a volume ratio of 1:1 to dissolve lithium hexafluorophosphate to obtain a concentration of 1 mol/L. The solution is placed in a jar made of tetrafluoroethylene resin and placed After storing in an oven at 85 ° C for one week, the test piece was taken out and the interface between the aluminum foil 4 and the ethylene-propylene random copolymer resin layer (inner layer) 3 was peeled off, and the laminate strength (adequate strength) between the two was measured (N/ 15mm wide).

<Measurement of total value (GU value) of exterior materials>

"micro-TRI-gloss-s" manufactured by BYK Corporation was used as a measuring machine at a reflection angle of 60°. Moreover, the total value (gloss of the surface on the side of the outer layer 2 on the side of the exterior material) was measured by the outer layer 2 of the exterior material.

As is clear from Table 1, the exterior materials of Examples 1 to 6 of the present invention have a large maximum forming depth, and excellent formability can be ensured when performing deep molding. Further, the materials of Examples 1 to 5 having a center line average roughness Ra of the surface on the inner layer side of the metal foil of 100 nm to 500 nm can maintain sufficient bonding strength for a long period of time and have excellent electrolyte resistance.

On the other hand, in the case where the center line average roughness Ra of the surface on the outer layer side of the metal foil was out of the range of 1 nm to 150 nm, the material was not contained, and good formability could not be ensured during deep molding.

[The possibility of industrial use]

The exterior material for an electrical storage device of the present invention can be, for example, as:

‧ Lithium secondary battery (lithium ion battery, lithium polymer battery, etc.)

‧Lithium ion capacitor

‧Electric double layer capacitor

Use of exterior materials such as various power storage devices.

This application is accompanied by an application filed on October 22, 2014. The priority of Japanese Patent Application No. 2014-214981, the disclosure of which is incorporated herein in its entirety.

The terms and descriptions used herein are for describing embodiments of the invention, but the invention is not limited thereto. It is to be understood that any equivalents of the features disclosed and described herein are not to be construed as limited.

1‧‧‧External materials for power storage devices

2‧‧‧Heat resistant resin layer (outer layer)

3‧‧‧ thermoplastic resin layer (inner layer)

4‧‧‧metal foil layer

4a‧‧‧Face on the outer side of the metal foil

4b‧‧‧ the side of the inner side of the metal foil

5‧‧‧1st adhesive layer

6‧‧‧2nd adhesive layer

Claims (8)

An exterior material for a power storage device, comprising: a heat resistant resin layer as an outer layer; a thermoplastic resin layer as an inner layer; and a metal foil layer disposed between the two layers; and the metal foil The center line average roughness (Ra) of the surface on the outer layer side is 1 nm to 150 nm. The exterior material for a storage battery device according to the first aspect of the invention, wherein the inner layer side surface of the metal foil has a center line average roughness (Ra) of 100 nm to 500 nm. The exterior material for a storage battery device according to the first aspect of the invention, wherein the surface of the metal foil on the outer layer side has a center line average roughness (Ra) of 5 nm to 100 nm. The exterior material for a storage battery device according to the first aspect of the invention, wherein the surface of the metal foil on the outer layer side has a center line average roughness (Ra) of 5 nm to 40 nm. The exterior material for a storage battery device according to the first aspect of the invention, wherein the surface of the outer side layer of the metal foil is formed with a chemical conversion coating film. The exterior material for a storage battery device according to the first aspect of the invention, wherein the metal foil is an aluminum foil having a thickness of 20 μm to 100 μm. The exterior material for a storage battery device according to the first aspect of the invention, wherein when the exterior material is visually observed from the outer layer side, the appearance is metallic luster, and the outer casing is measured by the outer layer side. The total value of the materials is 200~800. An electric storage device according to any one of the first to seventh aspects of the present invention, wherein: The main body of the power storage device is externally attached to the exterior material.