TWI775821B - Exterior material for power storage device and power storage device - Google Patents

Abstract

The present invention provides an exterior material 1 for an electrical storage device, which comprises a base material layer 2 made of a heat-resistant resin film, a sealing layer 3 of an inner layer, and a structure disposed between the base material layer 2 and the sealing layer 3 The metal foil layer 4 is composed of: the heat-resistant resin film constituting the base material layer is a heat-resistant resin film with a Young's modulus of 2.5GPa~4.5GPa; the thickness of the base material layer 2 is the metal foil layer 4 1.5 to 3.0 times the thickness. With this configuration, it is possible to provide an exterior material for an electrical storage device, which has excellent bending resistance without generating pinholes, cracks, or the like even if the exterior material is bent or the like.

Description

Exterior material for power storage device and power storage device

The present invention relates to batteries or capacitors used in portable devices such as smartphones and touch panels, and power storage devices such as batteries or capacitors used in hybrid vehicles, electric vehicles, wind power generation, solar power generation, and nighttime electrical power storage. Exterior materials and power storage devices mounted on the exterior materials.

In recent years, the technology of storing various kinds of information in IC cards, credit cards, etc. has progressed day by day. In order to exchange the information in such a large amount of information on the card, a huge amount of electricity is required. Conventionally, those who use magnetic beams using RFID tags and the like cannot obtain sufficient electric power.

In order to exchange information in a card with a large amount of information, a thin battery that can obtain sufficient power is required. When manufacturing thin batteries, thick exterior materials such as metal cans cannot be used due to the requirement of thinness, and due to the requirement of thinness, the battery elements (electrode plates, separators, etc.) arranged inside must be designed to be thin, With such thinning, it is difficult to ensure sufficient strength as a battery element, and there is a problem that the bending resistance of these battery elements is lowered.

Patent Document 1 describes an electronic device mounted with a thin battery. By specifying the relationship between the thickness of the entire current collector inside the thin battery and the thickness of the electronic device side where the thin battery is mounted, even if it is bent and deformed, it can be mounted. There will be no functional degradation such as disconnection of the battery. That is, Patent Document 1 describes an electronic device equipped with a thin battery, which is equipped with a sheet-shaped electrode group and a thin-type battery; the sheet-shaped electrode group is provided with a positive electrode, a negative electrode, and an electrode interposed between the positive electrode and the negative electrode. The electrolyte layer in between; the thin battery includes: an outer casing that seals the electrode group; a thickness h of the electrode group, a distance H1 from the top surface of the electrode group to the top surface of the electronic device on which the thin battery is mounted, and a distance H1 from the electrode group The distance H2 from the bottom of the cluster to the bottom of the electronic device mounted with the thin battery satisfies the relationship of 10≦H1/h and 10≦H2/h (refer to FIG. 6 of the patent document, etc.).

【Prior technical literature】 【Patent Literature】

[Patent Document 1] Japanese Patent Application Laid-Open No. 2013-161691

However, in the above-mentioned conventional technology, in order to prevent the reduction of the function caused by the mounted thin battery during bending deformation, the relationship between the thickness of the entire current collector of the thin battery and the thickness of the mounted electronic device side is not satisfied. A solution to the problem is achieved by specifying the constitution or structure of the thin battery itself. That is, in order to solve the problem, there is a problem in that there is a restriction on the configuration or structure of the electronic device side such as a card mounted with a battery.

The present invention has been made in view of the background of the related art, and an object of the present invention is to provide an exterior material for an electrical storage device which is excellent in bending resistance without generating pinholes or cracks even if it is subjected to bending deformation such as bending.

The present applicant completed the present invention by conducting intensive research to design a configuration or structure of the exterior material itself for a power storage device such as a battery that provides excellent bending resistance. That is, in order to achieve the aforementioned object, the present invention provides the following means.

[1] An exterior material for an electrical storage device, comprising a base material layer made of a heat-resistant resin film, a sealing layer of an inner layer, and a metal foil layer disposed between the base material layer and the sealing layer, It is characterized in that the heat-resistant resin film constituting the base material layer is a heat-resistant resin film with a Young's modulus of 2.5GPa~4.5GPa; the thickness of the base material layer is 1.5 times~3.0 times the thickness of the metal foil layer. times.

[2] The exterior material for an electricity storage device according to the above paragraph 1, wherein the thickness of the metal foil layer is 5 μm to 35 μm.

[3] The exterior material for an electricity storage device according to the above item 1 or 2, wherein the heat-resistant resin film constituting the base material layer is a polyester resin film.

[4] The exterior material for an electrical storage device according to any one of the above paragraphs 1 to 3, wherein the thickness of the exterior material for an electrical storage device is 70 μm to 120 μm.

[5] An outer casing for an electric storage device, characterized by being formed of a molded body of the outer casing for an electric storage device according to any one of the preceding paragraphs 1 to 4.

[6] An electrical storage device, characterized by comprising: a main body of the electrical storage device, the exterior material for an electrical storage device described in any one of Items 1 to 4 above, and/or the exterior casing for an electrical storage device described in Item 5 above and the main body of the power storage device is covered by the outer casing.

According to the invention of [1], since the heat-resistant resin film constituting the base material layer is a film having a Young's modulus of 2.5 GPa to 4.5 GPa, it is possible to provide an exterior material for a power storage device, which has the advantages of bending resistance and the like. It is excellent in bending resistance (bending recovery force), and even if it is bent or the like, pinholes, cracks, etc. will not occur in the exterior material. In addition, since the Young's modulus of the heat-resistant resin film constituting the base material layer is 4.5 GPa or less, favorable formability can be ensured as an exterior material for an electrical storage device. In addition, since the thickness of the base material layer is 1.5 to 3.0 times the thickness of the metal foil layer, it is possible to provide an exterior material for a power storage device whose thickness is thin (for example, a thickness of 60 μm to 90 μm). ), and also excellent in bending resistance (bending recovery force) such as bending resistance. In addition, this exterior material for an electrical storage device is also excellent in mechanical strength (physical strength) such as punching strength.

According to the invention of [2], since the thickness of the metal foil layer is 5 μm to 35 μm, it is possible to provide an exterior material for an electrical storage device which has further excellent bending resistance (bending recovery force) such as bending resistance.

According to the invention of [3], it is possible to provide an exterior material for a power storage device which is excellent in weather resistance such as water resistance.

According to the invention of [4], the heat sealability (heat sealability) of the exterior material for an electrical storage device can be improved.

According to the invention of [5], it is possible to provide an outer casing for a power storage device, which is excellent in bending resistance (bending recovery force) such as bending resistance, and which does not cause pinholes or pinholes in the outer casing even if it is bent or the like. cracks etc. In addition, even if the thickness of the outer casing is a thin structure (for example, a thickness of 60 μm to 90 μm), bending resistance (bending recovery force) such as bending resistance is excellent. In addition, the outer casing is also excellent in mechanical strength (physical strength) such as punching strength.

According to the invention of [6], since it is covered with an exterior material for a power storage device which is excellent in bending resistance (bending recovery force) such as bending resistance, it is possible to provide a power storage device whose exterior is not affected by bending or the like. The loading material still does not produce pinholes or cracks, etc.

1‧‧‧Exterior materials for power storage devices

2‧‧‧Substrate layer (outer layer)

3‧‧‧Sealing layer (inner layer)

4‧‧‧Metal foil layer

20‧‧‧Power storage device

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

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

An embodiment of the exterior material 1 for an electrical storage device of the present invention is shown in FIG. 1 . This exterior material 1 for a power storage device is used as a case for a lithium ion battery. That is, the said exterior material 1 for electric storage devices is used as an outer casing of a storage battery, etc., for example, by deep drawing, bulging, etc. shaping|molding.

The exterior material 1 for an electrical storage device is formed by laminating and integrating a heat-resistant resin film layer (outer layer; base material layer) 2 via a first adhesive layer 5 on one surface of the metal foil layer 4, and the metal The other side surface of the foil layer 4 is formed by laminating and integrating the second adhesive layer 6 and the hot-melt resin layer (inner layer; sealing layer) 3 .

In the exterior material 1 for a power storage device of the present invention, the heat-resistant resin film constituting the base material layer 2 is a heat-resistant resin film having a Young's modulus of 2.5 GPa to 4.5 GPa, and the thickness of the base material layer 2 is The thickness of the metal foil layer 4 is 1.5 times to 3.0 times the thickness. In the present invention, the heat-resistant resin film constituting the base material layer 2 is a heat-resistant resin film having a Young's modulus of 2.5 GPa to 4.5 GPa, so that an exterior material for an electrical storage device can be provided, which is resistant to bending, etc. The bending resistance (bending recovery force) is excellent, and even if it is bent, twisted, etc., the exterior material will not produce pinholes or cracks. Therefore, even if it is bent, bent, or the like, the power storage device can be prevented from being disconnected or liquid leaking. In addition, since the Young's modulus of the heat-resistant resin film constituting the base material layer 2 is 4.5 GPa or less, favorable moldability can be ensured when it is molded into the exterior material 1 for an electrical storage device. In addition, since the thickness of the base material layer 2 is 1.5 times to 3.0 times the thickness of the metal foil layer 4, it is possible to provide an exterior material 1 for a power storage device, even if the total thickness of the exterior material is thin (for example, 60 μm) ~90μm thickness), bending resistance (bending recovery force) such as bending resistance is still excellent.

When the Young's modulus of the heat-resistant resin film constituting the aforementioned base material layer 2 is less than 2.5 GPa, bending resistance such as bending resistance is lowered. In addition, when the Young's modulus of the heat-resistant resin film constituting the base material layer 2 exceeds 4.5 GPa, there may be problems such as pinholes or cracks in the exterior material when bent at a large angle. Among them, the Young's modulus of the heat-resistant resin film constituting the aforementioned base material layer 2 is preferably in the range of 3.0GPa to 4.0GPa.

If the thickness of the aforementioned base material layer 2 is less than 1.5 times the thickness of the aforementioned metal foil layer 4 , there is a problem that the strength of the outer covering material is likely to decrease due to the bending of the outer covering material. In addition, if the thickness of the base material layer 2 exceeds 3.0 times the thickness of the metal foil layer 4, there is a problem that the barrier properties of the exterior material are easily reduced due to the bending of the exterior material. Wherein, the thickness of the aforementioned base material layer 2 is preferably 2.0 times to 2.7 times the thickness of the aforementioned metal foil layer 4 .

As the heat-resistant resin constituting the aforementioned base material layer (outer layer) 2, a heat-resistant resin that does not melt at the heat-sealing temperature when the exterior material is heat-sealed is used. As the above-mentioned heat-resistant resin, it is preferable to use a heat-resistant resin having a melting point higher than that of the hot-melt resin constituting the hot-melt resin layer (sealing layer) 3 by 10°C or more, and it is preferable to use a heat-resistant resin having a melting point higher than that of the hot-melt resin. Heat-resistant resins with a melting point of 20°C or higher are particularly preferred.

The heat-resistant resin film layer (substrate layer) 2 is not particularly limited, and examples thereof include polyamide films such as nylon films, polyester films, polyolefin films, and polycarbonate films, and these are preferably used. stretch film. Among them, the above-mentioned heat-resistant resin film 2 is made of biaxially stretched polybutylene terephthalate (PBT) film, biaxially stretched polyethylene terephthalate (PET) film, biaxially stretched polyethylene naphthalate Biaxially stretched polyester films such as glycol ester (PEN) films are particularly preferred. The said nylon film is not specifically limited, For example, a 6 nylon film, a 6,6 nylon film, a MXD nylon film, etc. are mentioned. The heat-resistant resin film layer 2 may be formed as a single layer, or may be formed of, for example, a polyester film/polyamide film multi-layer (PET film/nylon film multi-layer, etc.). In the multi-layer structure exemplified above, it is preferable to arrange the polyester film on the outer side of the polyamide film, and similarly, it is preferable to arrange the PET film on the outer side of the nylon film.

The thickness of the heat-resistant resin film layer (substrate layer) 2 is preferably set to 9 μm to 100 μm. By setting it above the above ideal lower limit value, sufficient strength as an exterior material can be ensured, and by setting it below the above ideal upper limit value, the stress during forming such as bulging and stretching can be reduced. And the formability can be improved. Among them, the thickness of the heat-resistant resin film layer (substrate layer) 2 is particularly preferably set to 25 μm to 60 μm.

The aforementioned sealing layer (hot-melt resin layer) (inner layer) 3 has excellent chemical resistance against highly corrosive electrolytes used in lithium-ion batteries and the like, and is responsible for imparting heat-sealing properties to the exterior The role of material.

The above-mentioned hot-melt resin layer 3 is not particularly limited, and it is preferable that it is a hot-melt resin without a stretched film layer. The above-mentioned hot-melt resin does not have a stretched film layer 3, which is not particularly limited, but is heated by at least one selected from the group consisting of polyethylene, polypropylene, olefin-based copolymers, acid-denatured compounds of these, and ionomers. A non-stretching film made of molten resin is preferred. In addition, the aforementioned hot-melt resin layer 3 may be a single layer or a multiple layer.

The above-mentioned hot-melt resin layer 3 has a structure that includes at least a three-layer laminated structure, and the three-layer laminated structure is formed on both sides of an intermediate layer containing an olefin-based resin containing an elastomer component, and a coating containing an olefin-based resin is laminated. The structure of the layers, and the intermediate layer, preferably has a structure in which the elastomer component is an island-like sea-island structure.

The olefin-based resin containing the aforementioned elastomer component may be constituted by adding (mixing) an elastomer to the olefin-based resin, or may be an elastomer-modified olefin-based resin formed by chemically combining the olefin-based resin skeleton and the elastomer component. . In addition, the term "elastomer" mentioned above is used to mean that a rubber component is included.

The thickness of the aforementioned hot-melt resin layer 3 is preferably set at 20 μm to 80 μm. By setting it to 20 μm or more, the occurrence of pinholes can be sufficiently prevented, and by setting it to 80 μm or less, the amount of resin used can be reduced, and cost reduction can be achieved. Among them, the thickness of the hot-melt resin layer 3 is preferably set at 20 μm to 40 μm.

In addition, in order to improve moldability when molding the exterior material 1 for a power storage device, it is preferable that the hot-melt resin layer 3 contains a lubricant. The above-mentioned lubricant is not particularly limited, and examples thereof include saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, hydroxymethyl amides, saturated fatty acid diamides, unsaturated fatty acid diamides, and fatty acid esters. amides, aromatic diamides, etc.

The aforementioned metal foil layer 4 plays a role of imparting gas barrier properties to the exterior material 1 to prevent the intrusion of oxygen or moisture. The said metal foil layer 4 is not specifically limited, For example, aluminum foil, SUS foil (stainless steel foil), copper foil, nickel foil, etc. are mentioned, Generally, an aluminum foil is used. The thickness of the aforementioned metal foil layer 4 is preferably 5 μm˜35 μm. By being 5 μm or more, the generation of pinholes during rolling in the production of metal foil can be prevented, and by being 35 μm or less, the stress at the time of forming such as bulging and stretching can be reduced, and the formability can be improved. Among them, the thickness of the aforementioned metal foil layer 4 is preferably 9 μm to 25 μm.

The aforementioned metal foil layer 4 is preferably subjected to chemical conversion treatment on at least the inner surface (the surface on the side of the second adhesive layer 6). By performing such a chemical conversion treatment, the corrosion of the surface of the metal foil due to the contents (electrolyte of the battery, etc.) can be sufficiently prevented. For example, the metal foil can be subjected to chemical conversion treatment by the following treatment. That is, for example, on the surface of the metal foil subjected to the degreasing treatment, by coating the aqueous solution of any one of the following 1) to 3), and then drying, the chemical conversion treatment is applied: 1) Contains phosphoric acid, chromic acid, and an aqueous solution of a mixture of at least one compound selected from the group consisting of metal salts of fluorides and non-metallic salts of fluorides; 2) containing phosphoric acid, selected from acrylic resins, chitosan derivative resins and phenolic resins An aqueous solution of a mixture of at least one resin of the group and at least one compound selected from the group of chromic acid and chromium(III) salt. 3) Compounds containing phosphoric acid, at least one resin selected from the group consisting of acrylic resins, chitosan derivative resins and phenolic resins, and at least one selected from the group consisting of chromic acid and chromium (III) salts , and an aqueous solution of a mixture of at least one compound selected from the group consisting of metal salts of fluorides and non-metallic salts of fluorides.

For the aforementioned chemical film, the chromium adhesion amount (one side) is preferably 0.1 mg/m ² to 50 mg/m ² , and particularly preferably 2 mg/m ² to 20 mg/m ² .

The said 1st adhesive layer 5 is not specifically limited, For example, a polyurethane adhesive layer, a polyester polyurethane adhesive layer, a polyether polyurethane adhesive layer, etc. are mentioned. The thickness of the first adhesive layer 5 is preferably set to 1 μm to 5 μm. Among them, the thickness of the first adhesive layer 5 is preferably set to 1 μm to 3 μm from the viewpoint of thinning and weight reduction of the exterior material.

The second adhesive layer 6 is not particularly limited. For example, those exemplified as the first adhesive layer 5 can also be used. However, it is preferable to use a polyolefin-based adhesive with less swelling caused by the electrolyte. The thickness of the second adhesive layer 6 is preferably set at 1 μm to 5 μm. Among them, from the viewpoint of thinning and weight reduction of the exterior material, the thickness of the second adhesive layer 6 is particularly preferably set to 1 μm to 3 μm.

The thickness of the exterior material 1 for a power storage device of the present invention is preferably set to 70 μm to 120 μm, and particularly preferably set to 80 μm to 110 μm.

In the exterior material 1 for an electrical storage device of the present invention, a layer 1 or a plurality of other layers may be laminated on the outer side (the surface on the opposite side to the metal foil layer 4 side) of the heat-resistant resin film layer (base material layer) 2 .

By molding (deep drawing, bulging, etc.) of the exterior material 1 for a power storage device of the present invention, a molded case (battery case, etc.) can be obtained. Moreover, the exterior material 1 for electric storage devices of this invention can also be used without shaping|molding.

FIG. 2 shows an embodiment of the power storage device 20 constructed using the exterior material 1 of the present invention. This power storage device 20 is a lithium-ion storage battery.

The battery 20 includes an electrolyte 21 , a tab 22 , the unmolded flat outer casing 1 , and a molded case 11 (refer to FIG. 2 ) having a accommodating recess 11 b formed by molding the outer casing 1 . . The power storage device body portion 19 is constituted by the aforementioned electrolyte 21 and the aforementioned tabs 22 .

By accommodating the electrolyte 21 and a part of the tab 22 in the accommodating recess 11b of the molding case 11, the planar outer covering material 1 is arranged on the molding case 11, and the peripheral edge of the outer covering material 1 is arranged. The battery 20 is constituted by heat-sealing and bonding the portion (the inner layer 3 ) to the sealing peripheral portion 11 a (the inner layer 3 ) of the molded case 11 to form a heat-sealed portion (heat-sealed portion). In addition, the front end portion of the aforementioned contact piece 22 is led out from the outside (see FIG. 2 ).

【Example】

Next, specific embodiments of the present invention are described, but the present invention is not particularly limited to these embodiments.

<Example 1>

A chemical conversion treatment solution composed of phosphoric acid, polyacrylic acid (acrylic resin), chromium (III) salt compound, water, and ethanol was applied to both sides of an aluminum foil (metal foil) 4 with a thickness of 25 μm, and then dried at 180°C. Thereby forming a chemical film. The chromium adhesion amount of this chemical film is 10 mg/m ² per side.

Next, on the surface of one side of the aluminum foil 4 that has completed the chemical conversion treatment, a biaxially stretched polyethylene terephthalate with a thickness of 50 μm is passed through a 2-component curable urethane-based adhesive (outer adhesive) 5 A diester (PET) resin film (film for substrate layer) 2 is dry-laminated (bonded). The Young's modulus of the biaxially stretched polyethylene terephthalate (PET) resin film was 4.0 GPa.

Next, one side surface of a non-stretched polypropylene film (sealing film layer) 3 with a thickness of 30 μm was dry-laminated with the above-mentioned dry lamination through a 2-component curable urethane-based adhesive (inside adhesive) 6 . The other side of the aluminum foil 4 is superimposed, and it is dry-laminated by sandwiching it between rubber nip rolls and laminating rolls heated to 100°C, and then cured (heated) at 50°C. After 5 days, an exterior material 1 for a power storage device having a total thickness of 111 μm having the structure shown in FIG. 1 was obtained.

<Example 2>

Except that the metal foil 4 was an aluminum foil of 20 μm, and the total thickness of the exterior material was 106 μm, it was the same as that of Example 1, and the exterior material 1 for a power storage device shown in FIG. 1 was obtained.

<Example 3>

Except that the film 2 for the base layer is a biaxially stretched PET resin film with a thickness of 38 μm, the metal foil 4 is an aluminum foil of 20 μm, and the total thickness of the exterior material is 94 μm, other parts are the same as in Example 1. Figure 1 The shown exterior material 1 for a power storage device.

<Example 4>

Except for the film 2 for the base layer, a biaxially stretched PET resin film with a thickness of 38 μm is used, an aluminum foil with a thickness of 20 μm is used for the metal foil 4, and a non-stretch polypropylene film with a thickness of 20 μm is used for the sealing film 3. The total thickness of the exterior material Except that it is 84 micrometers, it is the same as that of Example 1, and the exterior material 1 for electric storage devices shown in FIG. 1 was obtained.

<Example 5>

In addition to the film 2 for the substrate layer, a co-extruded laminated film (arranged on the outside of the PET resin film) is a biaxially stretched PET resin film with a thickness of 30 μm/biaxially stretched nylon film with a thickness of 20 μm, and the metal foil 4 is a 20 μm thick film. The aluminum foil was the same as that of Example 1 except that the total thickness of the exterior material was 109 μm, and the exterior material 1 for a power storage device shown in FIG. 1 was obtained.

<Example 6>

In addition to the film 2 for the base layer, a co-extruded laminate film (arranged on the outer side of the PET resin film) using a biaxially stretched PET resin film with a thickness of 20 μm and a biaxially stretched nylon film with a thickness of 30 μm is used. The metal foil 4 uses a 20 μm film The aluminum foil was the same as that of Example 1 except that the total thickness of the exterior material was 109 μm, and the exterior material 1 for a power storage device shown in FIG. 1 was obtained.

<Example 7>

In addition to the film 2 for the base layer, a biaxially stretched nylon film with a thickness of 40 μm is used, a 25 μm aluminum foil is used for the metal foil 4, and a non-stretch polypropylene film with a thickness of 40 μm is used for the sealing film 3. The total thickness of the exterior material is 111 μm Other than that, it was the same as that of Example 1, and the exterior material 1 for electric storage devices shown in FIG. 1 was obtained.

<Comparative Example 1>

Except for the film for the substrate layer, which is a biaxially stretched nylon film with a thickness of 25 μm, an aluminum foil with a thickness of 40 μm for the metal foil, a non-stretch polypropylene film with a thickness of 40 μm for the sealing film, and the total thickness of the exterior material is 111 μm. In the same manner as in Example 1, an exterior material for an electrical storage device was obtained.

<Comparative Example 2>

Except that the film for the base layer was a biaxially stretched nylon film with a thickness of 15 μm, an aluminum foil of 35 μm was used for the metal foil, and the total thickness of the exterior material was 86 μm, the rest was the same as that of Example 1, and an exterior for an electric storage device was obtained. material.

<Comparative Example 3>

Except for the film for the substrate layer, a biaxially stretched PET resin film with a thickness of 12 μm is used, an aluminum foil with a thickness of 30 μm is used for the metal foil, a non-stretch polypropylene film with a thickness of 25 μm is used for the sealing film, and the total thickness of the exterior material is 73 μm. Others were the same as in Example 1, and an exterior material for an electrical storage device was obtained.

<Comparative Example 4>

Except for the film for the base layer, a biaxially stretched PET resin film with a thickness of 6 μm is used, an aluminum foil with a thickness of 20 μm is used for the metal foil, a non-stretch polypropylene film with a thickness of 20 μm is used for the sealing film, and the total thickness of the exterior material is 52 μm. Others were the same as in Example 1, and an exterior material for an electrical storage device was obtained.

<Comparative Example 5>

In addition to the film for the substrate layer, a co-extruded laminated film (arranged on the outer side of the PET resin film) using a biaxially stretched PET resin film with a thickness of 10 μm / a biaxially stretched nylon film with a thickness of 40 μm is used. The metal foil uses a 20 μm aluminum foil. Except that the total thickness of the exterior material was 109 μm, it was the same as in Example 1, and an exterior material for an electrical storage device was obtained.

<Comparative Example 6>

Except for the film for the substrate layer, a biaxially stretched PET resin film with a Young's modulus of 4.8 GPa and a thickness of 50 μm was used (the oligomer content of the biaxially stretched PET resin film used in Example 1 was different. Except for the difference in the modulus of

<Comparative Example 7>

Except that the film for the base layer is a biaxially stretched PET resin film with a thickness of 55 μm, an aluminum foil of 15 μm is used for the metal foil, and the total thickness of the exterior material is 106 μm, the rest is the same as that of Example 1, except that a power storage device is obtained. Loading material.

<Measuring method of Young's modulus>

For each film for base material layers before lamination used in the manufacture of exterior materials for electrical storage devices, in accordance with JIS K7127 (1999), a sample length of 100 mm, a sample width of 15 mm, a distance between evaluation points of 50 mm, and an extension speed of 200 mm The Young's modulus (unit: GPa) was calculated from the "stress-strain curve (SS curve)" obtained by measuring the elongation of a sample (a sample of a film for a substrate layer) using an elongation tester under the condition of 1/min. In the aforementioned stress-strain curve, "the inclination of the connection of the straight line portion" is the Young's modulus. The extension testing machine used "Strograph (AGS-5kNX)" manufactured by Shimadzu Corporation. The aforementioned term "Young's modulus" is synonymous with the Young's modulus defined in ASTM-D-882.

In addition, in Examples 5, 6 and Comparative Example 5, a laminate film was used as the film for the base material layer, and in this case, the Young's modulus was measured in the state of the laminate film.

<Bending resistance evaluation method>

For each exterior material for a power storage device, two test pieces of the following dimensions were prepared individually, and a bending test was carried out according to the flexural strength test method of JIS P8115 (2001).

Test machine: MIT TYPE FOLDING ENDURANCE TESTER (manufactured by Toyo Seiki Co., Ltd.)

Test piece size: 10mm wide x 150mm long

Load: 1.75kg

Bending speed: 175 round-trips/min

Bending angle: 90°

Bending front radius: 0.5R

Bending times: 750 times, 1500 times

Under the above test conditions, etc., one test piece was subjected to a bending test of 750 times, and the other test piece was subjected to a bending test of 1,500 times, and the exterior materials for electric storage devices after the individual tests were observed with the naked eye. state, and evaluated according to the following criteria.

(judgment criteria)

"◎"... No defects such as pinholes and cracks are found in the exterior material.

"○"...Although thin wrinkles and creases are visible at the bending position, there are no defects such as pinholes and cracks in the exterior material.

"△": At least one of the following three phenomena has occurred.

. The metal foil layer of the exterior material is cracked

. Pinholes occur in the substrate layer

. Pinholes in the sealing layer

"×"...The exterior material is broken.

As is apparent from Table 1, the exterior materials for power storage devices of Examples 1 to 7 of the present invention are thin exterior materials, but are excellent in bending resistance.

On the other hand, Comparative Examples 1 to 7, which deviate from the predetermined range of the present invention, were inferior in bending resistance.

【Industrial Availability】

As a specific example, the exterior material for a power storage device of the present invention can be used, for example:

． Power storage devices such as lithium batteries (lithium ion batteries, lithium polymer batteries, etc.)

. Lithium Ion Capacitors

． Electric double layer capacitor

. all-solid-state battery

Various external materials for power storage devices, etc. In addition, the exterior material for a power storage device of the present invention is excellent in bending resistance such as bending resistance even if the thickness is thin, so it can be suitably used as an exterior material for thin batteries (card-type batteries, etc.).

In addition, the power storage device of the present invention includes, for example, the various power storage devices exemplified above. Among them, thin-type batteries (card-type batteries, etc.) can be suitably used.

This application claims priority along with Japanese Patent Application No. 2017-44851 of Japanese Patent Application filed on March 9, 2017, and the disclosure thereof directly constitutes a part of this application.

The terms and descriptions used herein are used to describe the embodiments of the present invention, but the present invention is not limited thereto. Various modifications within the claimed scope of the present invention should also be understood to be acceptable.

1‧‧‧Exterior materials for power storage devices

2‧‧‧Substrate layer (outer layer)

3‧‧‧Sealing layer (inner layer)

4‧‧‧Metal foil layer

Claims (5)

An exterior material for an electrical storage device, comprising a base material layer made of a heat-resistant resin film, a sealing layer of an inner layer, and a metal foil layer disposed between the base material layer and the sealing layer, characterized by: The heat-resistant resin film constituting the base material layer is a heat-resistant resin film with a Young's modulus of 2.9GPa to 4.0GPa; the thickness of the base material layer is 1.9 times to 2.5 times the thickness of the metal foil layer; The heat-resistant resin film of the base material layer is formed of two layers or a single layer; the thickness of the base material layer is 25 μm~60 μm; the thickness of the metal foil layer is 20 μm~25 μm. The exterior material for an electrical storage device as described in claim 1, wherein the heat-resistant resin film constituting the base material layer is a polyester resin film. The exterior material for an electrical storage device according to claim 1, wherein the thickness of the exterior material for an electrical storage device is 70 μm to 120 μm. An outer casing for an electricity storage device, characterized by being formed of a molded body of the outer casing material for an electricity storage device as described in any one of claims 1 to 3 of the patent application. An electrical storage device characterized by comprising: a main body of the electrical storage device, the exterior material for an electrical storage device described in any one of claims 1 to 3 of the patent application, and/or the electrical storage device described in claim 4 An exterior member is formed by an exterior casing; and the main body portion of the power storage device is covered by the exterior member.

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