JP2018147860A - Power storage device exterior material and power storage device - Google Patents

Abstract

Provided is an exterior material for an electric storage device having excellent bending resistance in which pinholes, cracks, and the like do not occur in the exterior material even when subjected to bending or the like. The structure includes a base layer made of a heat-resistant resin film, a sealant layer as an inner layer, and a metal foil layer disposed between the base layer and the sealant layer. The heat-resistant resin film constituting the base layer 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 layer 2 is 1.5 times the thickness of the metal foil layer 4. Double to 3.0 times. [Selection diagram] Fig. 1

Description

  The present invention is for batteries and capacitors used for portable devices such as smartphones and tablets, hybrid vehicles, electric vehicles, wind power generation, solar power generation, storage devices such as batteries and capacitors used for storage of night electricity. The present invention relates to an exterior material and an electricity storage device that is exteriorized with the exterior material.

  In recent years, techniques for holding various information in cards such as IC cards and credit cards have been advanced. In order to exchange information in a card with such a large amount of information, a large amount of power is required. Conventionally, a device using magnetic flux such as an RFID tag has been used, but a sufficient amount of electric power has not been obtained.

  In order to exchange information in a card having a large amount of information, a thin battery capable of obtaining a sufficient amount of power is required. In order to manufacture a thin battery, a thin exterior material such as a metal can cannot be used because there is a demand for thinness, and a battery element (electrode plate, separator, etc.) disposed inside because there is a demand for thinness. Etc.) must be designed to be thin, and it is difficult to secure sufficient strength as a battery element due to such a thinning, and the bending resistance of these battery elements is reduced.

  In Patent Document 1, by defining the relationship between the thickness of the entire current collector inside the thin battery and the thickness of the electronic device on which the thin battery is mounted, functions such as disconnection of the mounted battery even when subjected to bending deformation There has been proposed a thin battery-equipped electronic device that does not cause a decrease. That is, Patent Document 1 discloses a thin battery including a positive electrode, a negative electrode, a sheet-like electrode group having an electrolyte layer interposed between the positive electrode and the negative electrode, and an outer package for sealing the electrode group. A thin battery-mounted electronic device mounted, wherein the electrode group has a thickness h, a distance H1 from the upper surface of the electrode group to the upper surface of the thin battery-mounted electronic device, and a distance from the lower surface of the electrode group to the lower surface of the thin battery-mounted electronic device. A thin battery-equipped electronic device that satisfies the relationship of H2 = 10 ≦ H1 / h and 10 ≦ H2 / h is described (see FIG. 6 of Patent Document).

JP2013-161691A

  However, the above-described prior art has a thickness of the entire current collector of the thin battery and a thickness on the electronic device side to be mounted so that the function deterioration due to the mounted thin battery does not occur when bending deformation is performed. This is not intended to be solved by defining the configuration and structure of the thin battery itself. That is, in order to solve the problem, there is a problem that the configuration and structure on the electronic device side such as a card on which a battery is mounted are limited.

  The present invention has been made in view of such a technical background, and provides an exterior material for an electricity storage device having excellent bending resistance that does not cause pinholes or cracks in the exterior material even when subjected to bending deformation such as bending. The purpose is to do.

  The present applicant has completed the present invention by conducting intensive research to provide a material having excellent bending resistance by devising the configuration and structure of the exterior material itself for a power storage device such as a battery. That is, in order to achieve the above object, the present invention provides the following means.

[1] In an exterior material for an electricity storage device comprising a base material layer made of a heat-resistant resin film, a sealant layer as an inner layer, and a metal foil layer disposed between the base material layer and the sealant layer,
The heat resistant resin film constituting the base material layer is a heat resistant resin film having a Young's modulus of 2.5 GPa to 4.5 GPa,
The thickness of the said base material layer is 1.5 times-3.0 times the thickness of the said metal foil layer, The exterior material for electrical storage devices characterized by the above-mentioned.

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

  [4] The power storage device exterior material according to any one of items 1 to 3, wherein the power storage device exterior material has a thickness of 70 μm to 120 μm.

  [5] An electricity storage device exterior case comprising the molded body of the electricity storage device exterior material according to any one of 1 to 4 above.

[6] A power storage device body,
The exterior member for an electricity storage device according to any one of items 1 to 4 and / or the exterior member comprising the exterior case for an energy storage device according to item 5 above,
The electricity storage device, wherein the electricity storage device body is covered with the exterior member.

  In the invention of [1], since the heat-resistant resin film constituting the base material layer has a Young's modulus of 2.5 GPa to 4.5 GPa, bending resistance such as bending resistance (bending recovery force) Thus, an exterior material for an electricity storage device is provided that is excellent in resistance and does not cause pinholes or cracks in the exterior material even when subjected to bending or the like. Moreover, since the Young's modulus of the heat resistant resin film constituting the base material layer is 4.5 GPa or less, good moldability is ensured as an exterior material for an electricity storage device. Moreover, since the thickness of the base material layer is 1.5 times to 3.0 times the thickness of the metal foil layer, the thickness of the exterior material is thin (for example, a thickness of 60 μm to 90 μm). In addition, an exterior material for an electricity storage device having excellent bending resistance such as bending resistance (bending recovery force) is provided. Moreover, this exterior material for an electricity storage device is also excellent in mechanical strength (physical strength) such as piercing strength.

  In the invention of [2], since the thickness of the metal foil layer is 5 μm to 35 μm, an exterior material for an electricity storage device that is superior in bending resistance (bending recovery force) such as bending resistance is provided.

  In the invention of [3], an exterior material for an electricity storage device having excellent weather resistance such as water resistance is provided.

  In the invention of [4], the heat sealing property (heat sealing property) of the exterior member for an electricity storage device can be improved.

  In the invention of [5], there is provided an outer case for an electricity storage device that is excellent in bending resistance (bending recovery force) such as bending resistance and that does not cause pinholes or cracks in the outer packaging even when subjected to bending or the like. . Further, even when the outer case is thin (for example, 60 μm to 90 μm thick), it has excellent bending resistance (bending recovery force) such as bending resistance. Moreover, this exterior case is also excellent in mechanical strength (physical strength) such as piercing strength.

  In the invention of [6], since it is packaged with an exterior material for an electricity storage device having excellent bending resistance (bending recovery force) such as bending resistance, pinholes and cracks are generated in the exterior material even when subjected to bending or the like. No electricity storage device is provided.

It is sectional drawing which shows one Embodiment of the exterior material for electrical storage devices which concerns on this invention. It is sectional drawing which shows one Embodiment of the electrical storage device comprised using the exterior material for electrical storage devices which concerns on this invention.

  One embodiment of an exterior material 1 for an electricity storage device according to the present invention is shown in FIG. The power storage device exterior material 1 is used for a lithium ion secondary battery case. In other words, the power storage device exterior material 1 is used as a case of a secondary battery by being subjected to molding such as deep drawing molding or stretch molding, for example.

  The power storage device exterior material 1 has a heat-resistant resin film layer (outer layer; base material layer) 2 laminated and integrated on one surface of a metal foil layer 4 via a first adhesive layer 5. The heat-fusing resin layer (inner layer; sealant layer) 3 is laminated and integrated on the other surface of the metal foil layer 4 via the second adhesive layer 6.

  In the power storage device exterior material 1 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 configured to be 1.5 to 3.0 times the thickness of the metal foil layer 4. In the present invention, since a heat-resistant resin film having a Young's modulus of 2.5 GPa to 4.5 GPa is used as the heat-resistant resin film constituting the base material layer 2, bending resistance such as bending resistance (bending recovery force) ), And an exterior material for an electricity storage device that does not cause pinholes or cracks in the exterior material even when subjected to bending, bending, or the like is provided. Therefore, even when subjected to bending, bending, or the like, a short circuit or liquid leakage in the electricity storage device can be prevented. Moreover, since the Young's modulus of the heat-resistant resin film constituting the base material layer 2 is 4.5 GPa or less, good moldability is ensured when the power storage device exterior material 1 is molded. Moreover, 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, the total thickness of the exterior material is thin (for example, a thickness of 60 μm to 90 μm). Even so, it is possible to provide the exterior device 1 for an electricity storage device that is excellent in bending resistance (bending recovery force) such as bending resistance.

  When the Young's modulus of the heat resistant resin film constituting the base material layer 2 is less than 2.5 GPa, bending resistance such as bending resistance is lowered. Moreover, when the Young's modulus of the heat-resistant resin film constituting the base material layer 2 exceeds 4.5 GPa, there is a problem that pinholes, cracks, and the like are likely to occur in the exterior material when bending at a large angle is performed. Especially, it is preferable that the Young's modulus of the heat resistant resin film which comprises the said base material layer 2 is the range of 3.0 GPa-4.0 GPa.

  When the thickness of the base material layer 2 is less than 1.5 times the thickness of the metal foil layer 4, there is a problem that the strength of the exterior material is likely to be reduced due to bending of the exterior material. Moreover, when 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 property of the exterior material is likely to be lowered due to the bending of the exterior material. Especially, it is preferable that the thickness of the base material layer 2 is 2.0 times to 2.7 times the thickness of the metal foil layer 4.

  As the heat-resistant resin constituting the base material layer (outer layer) 2, a heat-resistant resin that does not melt at the heat sealing temperature when heat-sealing the exterior material is used. As the heat resistant resin, it is preferable to use a heat resistant resin having a melting point higher by 10 ° C. than the melting point of the heat fusible resin constituting the heat fusible resin layer (sealant layer) 3. It is particularly preferable to use a heat-resistant resin having a melting point that is 20 ° C. higher than the melting point.

  The heat-resistant resin film layer (base material layer) 2 is not particularly limited, and examples thereof include polyamide films such as nylon films, polyester films, polyolefin films, and polycarbonate films. These stretched films Is preferably used. Among them, the heat-resistant resin film 2 is a biaxially stretched polyester film such as a biaxially stretched polybutylene terephthalate (PBT) film, a biaxially stretched polyethylene terephthalate (PET) film, or a biaxially stretched polyethylene naphthalate (PEN) film. It is particularly preferable to use it. The nylon film is not particularly limited, and examples thereof include 6 nylon film, 6,6 nylon film, MXD nylon film, and the like. The heat-resistant resin film layer 2 may be formed as a single layer or, for example, a multilayer composed of a polyester film / polyamide film (such as a multilayer composed of PET film / nylon film). May be. In the multilayer structure exemplified above, the polyester film is preferably disposed outside the polyamide film, and similarly, the PET film is preferably disposed outside the nylon film.

  The thickness of the heat resistant resin film layer (base material layer) 2 is preferably set to 9 μm to 100 μm. By setting it above the above preferred lower limit value, it is possible to ensure sufficient strength as an exterior material, and by setting it below the above preferred upper limit value, it is possible to reduce the stress at the time of molding such as stretch forming, draw forming, etc. and improve moldability Can be made. Especially, it is especially preferable that the thickness of the heat resistant resin film layer (base material layer) 2 is set to 25 μm to 60 μm.

  The sealant layer (heat-fusible resin layer) (inner layer) 3 has excellent chemical resistance against a highly corrosive electrolytic solution used in a lithium ion secondary battery or the like, and an exterior material. It plays a role of imparting heat-sealing properties.

  The heat-fusible resin layer 3 is not particularly limited, but is preferably a heat-fusible resin unstretched film layer. The heat-fusible resin unstretched film layer 3 is not particularly limited, but is at least one selected from the group consisting of polyethylene, polypropylene, olefin copolymers, acid-modified products thereof, and ionomers. It is preferably composed of an unstretched film made of a heat-fusible resin. The heat-fusible resin layer 3 may be a single layer or a multilayer.

  In particular, the heat-fusible resin layer 3 includes at least a three-layer laminated structure in which a coating layer containing an olefin resin is laminated on both surfaces of an intermediate layer containing an olefin resin containing an elastomer component. The intermediate layer preferably has a sea-island structure in which the elastomer component is an island.

  The olefin resin containing the elastomer component may have a structure in which an elastomer is added (blended) to the olefin resin, or an elastomer in which the elastomer component is chemically bonded to the olefin resin skeleton. It may be a modified olefin resin. The term “elastomer” is used to include a rubber component.

  The thickness of the heat-fusible resin layer 3 is preferably set to 20 μm to 80 μm. When the thickness is 20 μm or more, pinholes can be sufficiently prevented from being generated, and by setting the thickness to 80 μm or less, the amount of resin used can be reduced, and the cost can be reduced. In particular, the thickness of the heat-fusible resin layer 3 is particularly preferably set to 20 μm to 40 μm.

  In addition, when shape | molding in the exterior | packing material 1 for electrical storage devices, it is preferable to make the said heat-fusible resin layer 3 contain a lubricant for the improvement of a moldability. The lubricant is not particularly limited, and examples thereof include saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, methylol amides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, fatty acid ester amides, and aromatic bisamides. Can be mentioned.

  The metal foil layer 4 plays a role of imparting a gas barrier property to the exterior material 1 to prevent entry of oxygen and moisture. Although it does not specifically limit as said metal foil layer 4, For example, aluminum foil, SUS foil (stainless steel foil), copper foil, nickel foil etc. are mentioned, Aluminum foil is generally used. The thickness of the metal foil layer 4 is preferably 5 μm to 35 μm. When it is 5 μm or more, it is possible to prevent the occurrence of pinholes during rolling when manufacturing metal foil, and when it is 35 μm or less, it is possible to reduce the stress during forming such as stretch forming and draw forming, thereby improving formability. be able to. Especially, it is especially preferable that the thickness of the metal foil layer 4 is 9 μm to 25 μm.

The metal foil layer 4 is preferably subjected to a chemical conversion treatment on at least the inner surface (the surface on the second adhesive layer 6 side). By performing such a chemical conversion treatment, corrosion of the metal foil surface by the contents (battery electrolyte or the like) can be sufficiently prevented. For example, the metal foil is subjected to chemical conversion treatment by the following treatment. That is, for example, on the surface of the metal foil that has been degreased,
1) phosphoric acid;
Chromic acid,
An aqueous solution of a mixture comprising at least one compound selected from the group consisting of a metal salt of fluoride and a nonmetal salt of fluoride; 2) phosphoric acid;
At least one resin selected from the group consisting of acrylic resins, chitosan derivative resins and phenolic resins;
An aqueous solution of a mixture comprising at least one compound selected from the group consisting of chromic acid and a chromium (III) salt, 3) phosphoric acid,
At least one resin selected from the group consisting of acrylic resins, chitosan derivative resins and phenolic resins;
At least one compound selected from the group consisting of chromic acid and a chromium (III) salt;
An aqueous solution of a mixture comprising at least one compound selected from the group consisting of a fluoride metal salt and a fluoride non-metal salt. After applying an aqueous solution of any one of the above 1) to 3), drying is performed. Then, chemical conversion treatment is performed.

The conversion coating, chromium coating weight preferably is 0.1mg / m ² ~50mg / m ² as a (per one surface), in particular 2mg / m ² ~20mg / m 2 preferred.

  The first adhesive layer 5 is not particularly limited, and examples thereof include a polyurethane adhesive layer, a polyester polyurethane adhesive layer, and a polyether polyurethane adhesive layer. The thickness of the first adhesive layer 5 is preferably set to 1 μm to 5 μm. Especially, it is especially preferable that the thickness of the said 1st adhesive bond layer 5 is set to 1 micrometer-3 micrometers from a viewpoint of thickness reduction of an exterior material and weight reduction.

  Although it does not specifically limit as said 2nd adhesive bond layer 6, For example, what was illustrated as said 1st adhesive bond layer 5 can be used, However, The polyolefin-type adhesive agent with few swelling by electrolyte solution is used. Is preferred. The thickness of the second adhesive layer 6 is preferably set to 1 μm to 5 μm. Especially, it is especially preferable that the thickness of the said 2nd adhesive bond layer 6 is set to 1 micrometer-3 micrometers from a viewpoint of thickness reduction of an exterior material and weight reduction.

  The thickness of the power storage device exterior material 1 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 energy storage device exterior material 1 of the present invention, one or more other layers are laminated on the outer side of the heat resistant resin film layer (base material layer) 2 (on the surface opposite to the metal foil layer 4 side). May be.

  A molded case (battery case or the like) can be obtained by molding (deep drawing molding, stretch molding or the like) of the electricity storage device exterior material 1 of the present invention. In addition, the exterior | packing material 1 for electrical storage devices of this invention can also be used as it is, without providing for shaping | molding.

  One Embodiment of the electrical storage device 20 comprised using the exterior | packing material 1 of this invention is shown in FIG. The electricity storage device 20 is a lithium ion secondary battery.

  The battery 20 includes an electrolyte 21, a tab lead 22, the planar outer packaging material 1 that is not used for molding, and a molding case 11 having an accommodation recess 11 b obtained by molding the outer packaging material 1. (See FIG. 2). The electrolyte 21 and the tab lead 22 constitute a power storage device main body 19.

  A part of the electrolyte 21 and the tab lead 22 is accommodated in the accommodating recess 11 b of the molding case 11, the planar exterior material 1 is disposed on the molding case 11, and a peripheral portion ( The inner layer 3) and the sealing peripheral edge portion 11a of the molded case 11 (the inner layer 3) are joined by heat sealing to form a heat sealing portion (heat sealing portion), whereby the battery 20 is formed. Is configured. The leading end of the tab lead 22 is led out to the outside (see FIG. 2).

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

<Example 1>
After applying a chemical conversion treatment solution composed of phosphoric acid, polyacrylic acid (acrylic resin), chromium (III) salt compound, water, alcohol on both sides of an aluminum foil (metal foil) 4 having a thickness of 25 μm, the temperature is 180 ° C. Drying was performed to form a chemical conversion film. The amount of chromium deposited on this chemical film was 10 mg / m ² per side.

  Next, a biaxially stretched polyethylene terephthalate (PET) resin film (base) having a thickness of 50 μm is formed on one surface of the chemical conversion-treated aluminum foil 4 via a two-component curable urethane adhesive (outer adhesive) 5. The material layer film) 2 was dry laminated (bonded). The Young's modulus of this biaxially stretched polyethylene terephthalate (PET) resin film is 4.0 GPa.

  Next, the dry-laminated aluminum foil 4 is placed on one surface of a 30 μm-thick unstretched polypropylene film (sealant film layer) 3 via a two-component curable urethane adhesive (inner adhesive) 6. By laminating the other surface, sandwiching between a rubber nip roll and a laminating roll heated to 100 ° C. and press-bonding, and then aging (heating) at 50 ° C. for 5 days As a result, an exterior packaging material 1 for an electricity storage device having a total thickness of 111 μm having the configuration shown in FIG. 1 was obtained.

<Example 2>
A power storage device exterior material 1 shown in FIG. 1 was obtained in the same manner as in Example 1 except that a 20 μm aluminum foil was used as the metal foil 4 and the total thickness of the exterior material was 106 μm.

<Example 3>
The same as Example 1 except that a biaxially stretched PET resin film with a thickness of 38 μm was used as the substrate layer film 2, an aluminum foil with a thickness of 20 μm was used as the metal foil 4, and the total thickness of the exterior material was 94 μm. Thus, the exterior device 1 for an electricity storage device shown in FIG. 1 was obtained.

<Example 4>
A biaxially stretched PET resin film with a thickness of 38 μm is used as the base film 2, an aluminum foil with a thickness of 20 μm is used as the metal foil 4, and an unstretched polypropylene film with a thickness of 20 μm is used as the sealant film 3. 1 was obtained in the same manner as in Example 1 except that the total thickness of the material was 84 μm.

<Example 5>
As the base layer film 2, a 30 μm-thick biaxially stretched PET resin film / a 20 μm-thick biaxially stretched nylon film coextruded laminated film (PET resin film is disposed on the outer side) is used as the metal foil 4. A power storage device exterior material 1 shown in FIG. 1 was obtained in the same manner as in Example 1 except that a 20 μm aluminum foil was used and the total thickness of the exterior material was 109 μm.

<Example 6>
As the base layer film 2, a 20 μm-thick biaxially stretched PET resin film / 30 μm-thick biaxially stretched nylon film coextruded laminated film (PET resin film is disposed on the outer side) is used as the metal foil 4. A power storage device exterior material 1 shown in FIG. 1 was obtained in the same manner as in Example 1 except that a 20 μm aluminum foil was used and the total thickness of the exterior material was 109 μm.

<Example 7>
A biaxially stretched nylon film having a thickness of 40 μm is used as the base film 2, an aluminum foil having a thickness of 25 μm is used as the metal foil 4, and an unstretched polypropylene film having a thickness of 40 μm is used as the sealant film 3. 1 was obtained in the same manner as in Example 1 except that the thickness was 111 μm.

<Comparative Example 1>
A biaxially stretched nylon film with a thickness of 25 μm is used as the film for the substrate layer, an aluminum foil with a thickness of 40 μm is used as the metal foil, an unstretched polypropylene film with a thickness of 40 μm is used as the sealant film, and the total thickness of the exterior material is set. An exterior material for an electricity storage device was obtained in the same manner as in Example 1 except that the thickness was 111 μm.

<Comparative Example 2>
As in Example 1, except that a biaxially stretched nylon film with a thickness of 15 μm was used as the base layer film, an aluminum foil with a thickness of 35 μm was used as the metal foil, and the total thickness of the exterior material was 86 μm. An exterior material for an electricity storage device was obtained.

<Comparative Example 3>
The total thickness of the exterior material is a biaxially stretched PET resin film with a thickness of 12 μm as the film for the base material layer, an aluminum foil with a thickness of 30 μm is used as the metal foil, and an unstretched polypropylene film with a thickness of 25 μm is used as the sealant film. Was obtained in the same manner as in Example 1 except that the thickness was 73 μm.

<Comparative example 4>
The total thickness of the exterior material is a biaxially stretched PET resin film having a thickness of 6 μm as the film for the base material layer, an aluminum foil having a thickness of 20 μm is used as the metal foil, and an unstretched polypropylene film having a thickness of 20 μm is used as the sealant film. Was obtained in the same manner as in Example 1 except that the thickness was 52 μm.

<Comparative Example 5>
As the base layer film, a 10 μm thick biaxially stretched PET resin film / a 40 μm thick biaxially stretched nylon film co-extruded laminated film (PET resin film is disposed on the outer side) and a metal foil of 20 μm An exterior material for an electricity storage device was obtained in the same manner as in Example 1 except that aluminum foil was used and the total thickness of the exterior material was set to 109 μm.

<Comparative Example 6>
As a film for a substrate layer, a Biaxially stretched PET resin film having a Young's modulus of 4.8 GPa and a thickness of 50 μm (the oligomer content is different from the biaxially stretched PET resin film used in Example 1, and the Young's modulus is also Except for using (different), an exterior material for an electricity storage device was obtained in the same manner as in Example 1.

<Comparative Example 7>
As in Example 1, except that a biaxially stretched PET resin film having a thickness of 55 μm was used as the base layer film, an aluminum foil having a thickness of 15 μm was used as the metal foil, and the total thickness of the exterior material was 106 μm. Thus, an exterior material for an electricity storage device was obtained.

<Measurement method of Young's modulus>
About each base material layer film before lamination used for manufacturing an exterior material for an electricity storage device, in accordance with JIS K7127 (1999), a sample length is 100 mm, a sample width is 15 mm, a distance between ratings is 50 mm, and a tensile speed is 200 mm / min. The Young's modulus (unit: GPa) was calculated from a “stress-strain curve (SS curve)” obtained by tensile measurement of a sample piece (sample piece of a base layer film) under the above conditions. “Slope of tangent of straight line portion” in the stress-strain curve is Young's modulus. “Strograph (AGS-5kNX)” manufactured by Shimadzu Corporation was used as a tensile tester. The term “Young's modulus” is synonymous with Young's modulus defined in ASTM-D-882.

  In Examples 5 and 6 and Comparative Example 5, a laminated film is used as the base layer film. In this case, the Young's modulus is measured in the laminated film state.

<Bending resistance evaluation method>
Two test pieces of the following sizes were prepared for each of the power storage device exterior materials, and a bending test was performed in accordance with the fold strength test method of JIS P8115 (2001).

Test equipment: MIT TYPE FOLDING ENDURANCE TESTER (Toyo Seiki Seisakusho)
Test piece size: 10 mm width x 150 mm length Load: 1.75 kg
Bending speed: 175 reciprocations / minute ("bending and return" is counted as one reciprocation)
Bending angle: 90 °
Bending tip radius: 0.5R
Number of bending: 750 times, 1500 times Under the above test conditions, one test piece was subjected to 750 times bending test, and the other test piece was subjected to 1500 times bending test, and the exterior for the electricity storage device after each test The state of the material was visually examined and evaluated based on the following criteria.
(Criteria)
“A”: Defects such as pinholes and cracks were not observed in the exterior material.
“◯”: A thin crease was observed at the bent portion, but no defects such as pinholes and cracks were observed in the exterior material.
“Δ”: At least one of the following three phenomena occurred.

・ A crack occurred in the metal foil layer of the exterior material. ・ A pinhole occurred in the base material layer. ・ A pinhole occurred in the sealant layer. “X”: A fracture occurred in the exterior material.

  As is apparent from Table 1, the power storage device exterior materials of Examples 1 to 7 of the present invention were excellent in bending resistance while being thin.

  On the other hand, in Comparative Examples 1-7 which deviate from the prescription | regulation range of this invention, it was inferior to bending resistance.

As a specific example, an exterior material for an electricity storage device according to the present invention is, for example,
-Power storage devices such as lithium secondary batteries (lithium ion batteries, lithium polymer batteries, etc.)-Used as exterior materials for various power storage devices such as lithium ion capacitors, electric double layer capacitors, all solid state batteries Moreover, since the exterior material for an electricity storage device according to the present invention is excellent in bending resistance such as bending resistance even when the thickness is thin, it is suitable as an exterior material for a thin battery (such as a card type battery). is there.

  In addition, examples of the electricity storage device according to the present invention include the various electricity storage devices exemplified above. Especially, it is suitable as a thin battery (card type battery etc.).

DESCRIPTION OF SYMBOLS 1 ... Exterior material for electrical storage devices 2 ... Base material layer (outer layer)
3. Sealant layer (inner layer)
4 ... Metal foil layer 20 ... Electric storage device

Claims (6)

In an exterior device for an electricity storage device comprising a base material layer made of a heat-resistant resin film, a sealant layer as an inner layer, and a metal foil layer disposed between the base material layer and the sealant layer,
The heat resistant resin film constituting the base material layer is a heat resistant resin film having a Young's modulus of 2.5 GPa to 4.5 GPa,
The thickness of the said base material layer is 1.5 times-3.0 times the thickness of the said metal foil layer, The exterior material for electrical storage devices characterized by the above-mentioned.   The power storage device exterior material according to claim 1, wherein the metal foil layer has a thickness of 5 μm to 35 μm.   The heat storage resin film according to claim 1 or 2, wherein the heat-resistant resin film constituting the base material layer is a polyester resin film.   The thickness of the said electricity storage device exterior material is 70 micrometers-120 micrometers, The electrical storage device exterior material of any one of Claims 1-3.   The exterior case for electrical storage devices which consists of a molded object of the exterior material for electrical storage devices of any one of Claims 1-4. An electricity storage device body,
An exterior member made of the exterior material for an electricity storage device according to any one of claims 1 to 4 and / or the exterior case for an electricity storage device according to claim 5,
The electricity storage device, wherein the electricity storage device body is covered with the exterior member.

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