Exterior materials for energy storage devices

Abstract

To provide an exterior material for a power storage device which has excellent yellowing resistance, obtains sufficient adhesive strength of an outer adhesive, and also has good moldability.SOLUTION: The exterior material for a power storage device includes a substrate layer 2 as an outer layer, a heat-fusible resin layer 3 as an inner layer, and a metal foil layer 4 arranged between both the layers. The substrate layer 2 and the metal foil layer 4 are bonded via an outer adhesive layer 5. The outer adhesive layer 5 is formed of a cured film of a two-pack curable urethane adhesive which contains a main agent containing a polyol, and a polyfunctional isocyanate mixture, the content of the polyol being 50-95 mas%. The polyfunctional isocyanate mixture is composed of a mixture containing an aromatic polyfunctional isocyanate and an aliphatic polyfunctional isocyanate having an aromatic ring.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a packaging material for electricity storage devices such as batteries and capacitors used in mobile devices such as smartphones and tablets, and batteries and capacitors used in hybrid vehicles, electric vehicles, wind power generation, solar power generation, and storing nighttime electricity, and to an electricity storage device packaged with the packaging material.

[0002] In this specification and claims, the term "aromatic polyfunctional isocyanate" refers to a polyfunctional isocyanate having a chemical structural formula in which the N atom of -NCO (isocyanate functional group) is directly bonded to a C atom constituting an aromatic ring (benzene ring), and the term "aliphatic polyfunctional isocyanate having an aromatic ring" refers to a polyfunctional isocyanate having a chemical structural formula in which the N atom of -NCO (isocyanate functional group) is bonded to a C atom constituting an aromatic ring (benzene ring) via one or more linking groups such as methylene groups. In other words, the term "aliphatic polyfunctional isocyanate having an aromatic ring" does not include a polyfunctional isocyanate having a chemical structural formula in which the N atom of -NCO (isocyanate functional group) is directly bonded to a C atom constituting an aromatic ring (benzene ring). [Background technology]

[0003] In recent years, as mobile electrical devices such as smartphones and tablet terminals have become thinner and lighter, laminates consisting of a heat-resistant resin layer / an outer adhesive layer / a metal foil layer / an inner adhesive layer / a heat-sealable resin layer (an inner sealant layer) have been used instead of conventional metal cans as the exterior packaging materials for the lithium-ion secondary batteries, lithium polymer secondary batteries, lithium-ion capacitors, electric double-layer capacitors, and other power storage devices installed in these devices. Furthermore, power sources for electric vehicles and the like, large-scale power sources for power storage applications, capacitors, and the like are increasingly being packaged with laminates (exterior packaging materials) having the above-described configurations. The laminates are molded into a three-dimensional shape, such as a roughly rectangular parallelepiped, by stretch molding or deep drawing. Molding into such a three-dimensional shape ensures that a storage space for the main body of the power storage device can be secured.

[0004] It is known to use an adhesive containing a polyfunctional isocyanate as an outer adhesive to prevent delamination (peeling) between the heat-resistant resin layer and the metal layer (see Patent Document 1). Patent Document 1 describes that tolylene diisocyanate is preferably used as the polyfunctional isocyanate. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 4380728 Summary of the Invention [Problem to be solved by the invention]

[0006] However, battery casing materials that use tolylene diisocyanate as a polyfunctional isocyanate have a problem in that the outer adhesive layer yellows due to contact with the electrolyte in an atmosphere where the material comes into contact with the electrolyte, resulting in a poor appearance. Of course, care can be taken during production to prevent contact with the electrolyte, but in practice, it is difficult to prevent the electrolyte from adhering to the casing material during production, etc. Therefore, there has been a need for a composition that prevents the outer adhesive itself from yellowing even when the electrolyte is adhering to the casing material.

[0007] The present invention has been made in view of this technical background, and aims to provide an exterior material for an electricity storage device that has excellent yellowing resistance, sufficient adhesive strength for the outer adhesive, and good formability, and an electricity storage device exteriorized with the exterior material. [Means for solving the problem]

[0008] In order to achieve the above object, the present invention provides the following means.

[0009] [1] An exterior packaging material for an electricity storage device, comprising a base material layer as an outer layer, a heat-sealable resin layer as an inner layer, and a metal foil layer disposed between these layers, the substrate layer and the metal foil layer are bonded via an outer adhesive layer, the outer adhesive layer is formed of a cured film of a two-component curing urethane adhesive containing a polyol-containing base agent and a polyfunctional isocyanate mixture, the polyol content of which is 50% by mass to 95% by mass; The packaging material for an electricity storage device is characterized in that the polyfunctional isocyanate mixture is a mixture containing an aromatic polyfunctional isocyanate and an aliphatic polyfunctional isocyanate having an aromatic ring.

[0010] [2] The packaging material for a storage battery device according to item 1, wherein the content of the aromatic polyfunctional isocyanate in the polyfunctional isocyanate mixture is 5% by mass to 50% by mass, and the content of the aliphatic polyfunctional isocyanate having an aromatic ring in the polyfunctional isocyanate mixture is 50% by mass to 95% by mass.

[0011] [3] The polyol is a polyester polyol, The polyester polyol contains a dicarboxylic acid component, 3. The packaging material for an electricity storage device according to item 1 or 2 above, wherein the dicarboxylic acid component contains an aromatic dicarboxylic acid, and the content of the aromatic dicarboxylic acid in the dicarboxylic acid component is 40 mol % to 80 mol %.

[0012] [4] The packaging material for an electricity storage device according to any one of items 1 to 3 above, wherein the aliphatic polyfunctional isocyanate having an aromatic ring is one or more isocyanates selected from the group consisting of xylylene diisocyanate and modified products thereof.

[0013] [5] The exterior packaging material for an electricity storage device according to any one of items 1 to 4 above, wherein the two-component curing urethane adhesive forms a cured film with a Young's modulus of 90 MPa to 400 MPa.

[0014] [6] An exterior case for an electricity storage device, which is made of a molded article of the exterior material for an electricity storage device according to any one of items 1 to 5 above.

[0015] [7] A main body of the power storage device; The electrical storage device packaging material according to any one of items 1 to 5 above and the electrical storage device packaging case according to claim 6 are included in one or two packaging members selected from the group consisting of: The power storage device, wherein the power storage device main body is sheathed with the sheathing member. [Effects of the Invention]

[0016] In the invention [1], the polyfunctional isocyanate mixture is composed of a mixture containing an aromatic polyfunctional isocyanate and an aliphatic polyfunctional isocyanate having an aromatic ring, so that the outer adhesive layer is less likely to yellow, the exterior material has excellent yellowing resistance, and the outer adhesive has sufficient adhesive strength and good moldability.

[0017] In the invention [2], the yellowing resistance can be further improved, the moldability can be improved, and the adhesive strength of the outer adhesive can also be improved.

[0018] In the invention [3], polyester polyol is used as the polyol, and the content of aromatic dicarboxylic acid in the dicarboxylic acid component is 40 mol % or more, so that delamination (peeling) between the outer layer and the metal foil layer can be more sufficiently prevented, and the content of aromatic dicarboxylic acid in the dicarboxylic acid component is 80 mol % or less, so that the adhesive strength of the outer adhesive can be more sufficiently ensured.

[0019] The invention [4] can further improve the resistance to yellowing.

[0020] In the invention [5], the Young's modulus of the cured film of the two-component curing urethane adhesive is 90 MPa or more, thereby improving the heat resistance of the outer adhesive layer and more adequately preventing delamination (peeling) between the outer layer and the metal foil layer during heat sealing. Furthermore, the Young's modulus is 400 MPa or less, which not only ensures more adequate adhesive strength of the outer adhesive but also improves high-temperature lamination strength.

[0021] In the invention [6], the outer adhesive layer is resistant to yellowing, making the exterior material highly resistant to yellowing, while the adhesive strength of the outer adhesive is sufficiently ensured, making it possible to provide an exterior case for an electricity storage device that is well molded.

[0022] The invention [7] can provide an electricity storage device that is packaged with an exterior member that has excellent yellowing resistance and ensures sufficient adhesive strength of the outer adhesive. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a cross-sectional view showing one embodiment of an exterior packaging material for an electricity storage device according to the present invention. [Figure 2] 1 is a cross-sectional view showing an embodiment of an electricity storage device according to the present invention. [Figure 3] 3 is a perspective view showing the exterior material (flat), the electricity storage device main body, and the exterior case (a molded article molded into a three-dimensional shape) that constitute the electricity storage device of FIG. 2 in a separated state before being heat-sealed. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0024] One embodiment of an exterior packaging material 1 for an electricity storage device according to the present invention is shown in Fig. 1. This exterior packaging material 1 for an electricity storage device is used for a lithium ion secondary battery case.

[0025] The packaging material 1 for an electricity storage device has a configuration in which a base material layer (outer layer) 2 is laminated integrally on one surface of a metal foil layer 4 via an outer adhesive layer 5, and a heat-sealable resin layer (inner layer) 3 is laminated integrally on the other surface of the metal foil layer 4 via an inner adhesive layer 6.

[0026] In the exterior packaging material 1 for a storage battery device according to the present invention, the outer adhesive layer 5 is formed of a cured film of a two-component curing urethane adhesive containing a polyol-containing main agent and a polyfunctional isocyanate mixture, with the polyol content being 50% by mass to 95% by mass, and the polyfunctional isocyanate mixture being composed of a mixture containing an aromatic polyfunctional isocyanate and an aliphatic polyfunctional isocyanate having an aromatic ring. Therefore, the outer adhesive layer is resistant to yellowing, and the exterior packaging material has excellent yellowing resistance, and the outer adhesive has sufficient adhesive strength and good formability.

[0027] In the present invention, the main agent constituting the two-component curing urethane adhesive contains a polyol, and preferably contains 50% by mass or more of polyol. When the polyol content in the main agent is 50% by mass or more, the adhesive strength can be further increased and delamination (peeling) between the outer layer 2 and the metal foil layer 4 can be sufficiently prevented. In particular, the polyol content in the main agent is more preferably 70% by mass or more, and even more preferably 90% by mass or more.

[0028] The polyol is not particularly limited, and examples thereof include polyester polyol, polyether polyol, polycaprolactone diol, etc. In the present invention, polyester polyol includes urethane-modified polyester polyol (polyester polyurethane polyol, etc.), and polyether polyol includes urethane-modified polyether polyol (polyether polyurethane polyol, etc.). Among them, it is preferable to use a copolymer polyester polyol made from dicarboxylic acid and dialcohol as the raw material as the polyol. In the present invention, by appropriately selecting the type and composition of the dicarboxylic acid and dialcohol raw material, it is possible to further increase the adhesive strength and prevent delamination even when deeper molding is performed.

[0029] The dicarboxylic acid is not particularly limited, but examples thereof include aliphatic dicarboxylic acids, aromatic dicarboxylic acids, etc. The aliphatic dicarboxylic acids are not particularly limited, but examples thereof include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, etc. The aromatic dicarboxylic acids are not particularly limited, but examples thereof include phthalic acid, isophthalic acid, terephthalic acid, etc.

[0030] The dialcohol is not particularly limited, but examples thereof include ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, diethylene glycol, dipropylene glycol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, octanediol, 1,4-cyclohexanediol, and 2-butyl-2-ethyl-1,3-propanediol.

[0031] When a polyester polyol is used as the polyol, the polyester polyol preferably contains a dicarboxylic acid component (including a dicarboxylic acid ester derived from a dicarboxylic acid), and the dicarboxylic acid component preferably contains an aromatic dicarboxylic acid. The content of the aromatic dicarboxylic acid in the dicarboxylic acid component is preferably 40 mol% to 80 mol%, more preferably 50 mol% to 70 mol%.

[0032] The number average molecular weight (Mn) of the polyol is preferably in the range of 8,000 to 25,000, in which case the outer adhesive layer 5 can be given appropriate coating strength and coating elongation.

[0033] The number-average molecular weight of the polyester polyol can be adjusted by chain extension with a polyfunctional isocyanate. Specifically, when the polyester component in the base resin is linked with NCO, a polymer with terminal hydroxyl groups is produced, and the number-average molecular weight of the polyester polyol can be adjusted by adjusting the equivalent ratio between the isocyanate group and the polyester hydroxyl group. In the present invention, it is preferable to use a polyester polyol linked so that this equivalent ratio (OH / NCO) is in the range of 1.01 to 10. Another molecular weight adjustment method is to adjust the reaction conditions (e.g., the molar ratio of the dicarboxylic acid and the dialcohol) for the polycondensation reaction of the dicarboxylic acid and the dialcohol.

[0034] The base agent may be prepared by adding, for example, a polyhydric alcohol to the polyol, which is an essential component. The polyhydric alcohol is not particularly limited, but examples thereof include trimethylolpropane (TMP), methylpentanediol, dimethylbutanediol, ethylene glycol, 1,4-butanediol, glycerin, and sorbitol.

[0035] The polyfunctional isocyanate mixture is a mixture containing an aromatic polyfunctional isocyanate and an aliphatic polyfunctional isocyanate having an aromatic ring.

[0036] The aromatic polyfunctional isocyanate is not particularly limited, but examples thereof include tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), triphenylmethane triisocyanate, etc. Among these, it is preferable to use one or more aromatic polyfunctional isocyanates selected from the group consisting of tolylene diisocyanate, diphenylmethane diisocyanate, and polyfunctional isocyanate modified products of at least one of these diisocyanates. The modification method is not particularly limited, but examples thereof include adducts with polyfunctional active hydrogen compounds such as water, glycerin, and trimethylolpropane, as well as polyfunctional isocyanate modified products obtained by polymerization reactions such as isocyanuration, carbodiimidization, and polymerization.

[0037] The aliphatic polyfunctional isocyanate having an aromatic ring is not particularly limited, but examples thereof include xylylene diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI), and polyfunctional isocyanate modified products of at least one of these diisocyanates. The modification method is not particularly limited, but examples thereof include adducts with polyfunctional active hydrogen compounds such as water, glycerin, and trimethylolpropane, as well as polyfunctional isocyanate modified products obtained by polymerization reactions such as isocyanuration, carbodiimidization, and polymerization. Among these, it is preferable to use one or more isocyanates selected from the group consisting of xylylene diisocyanate and modified products thereof.

[0038] Preferably, the content of the aromatic polyfunctional isocyanate in the polyfunctional isocyanate mixture is 5% by mass to 50% by mass, and the content of the "aliphatic polyfunctional isocyanate having an aromatic ring" in the polyfunctional isocyanate mixture is 50% by mass to 95% by mass. In this case, it is possible to further improve yellowing resistance, moldability, and the adhesive strength of the outer adhesive 5. When the content of the aromatic polyfunctional isocyanate is 5% by mass or more, moldability can be further improved, and when the content of the aromatic polyfunctional isocyanate is 50% by mass or less, yellowing resistance can be further improved. When the content of the aliphatic polyfunctional isocyanate having an aromatic ring is 50% by mass or more, yellowing resistance can be further improved, and when the content of the aliphatic polyfunctional isocyanate having an aromatic ring is 95% by mass or less, moldability can be further improved.

[0039] In the two-component curing urethane adhesive (cured urethane adhesive film), the content of the polyol component is set to 50% by mass to 95% by mass. A polyol component content of 50% by mass or more can sufficiently improve the adhesive strength of the outer adhesive, and a polyol component content of 95% by mass or less can ensure sufficient sealing resistance. In particular, in the two-component curing urethane adhesive, the content of the polyol component is preferably 60% by mass to 90% by mass. Also, in the two-component curing urethane adhesive, the content of the polyfunctional isocyanate mixture is preferably 40% by mass to 10% by mass. Furthermore, in the two-component curing urethane adhesive (cured urethane adhesive film), the content of the polyol component is more preferably 70% by mass to 90% by mass and the content of the polyfunctional isocyanate mixture is more preferably 30% by mass to 10% by mass.

[0040] In the two-component curing urethane adhesive described above, which comprises a polyol as the base component and a polyfunctional isocyanate mixture as the curing agent, it is preferable that the isocyanate groups (-NCO) of the polyfunctional isocyanate mixture be blended in a ratio of 1 mole to 30 moles per mole of hydroxyl groups (-OH) of the polyol. A molar ratio ([NCO] / [OH]) of 1 or greater ensures sufficient curing reaction, resulting in appropriate coating strength and heat resistance. Furthermore, a molar ratio ([NCO] / [OH]) of 30 or less prevents excessive reaction with functional groups other than the polyol, resulting in appropriate coating strength and elongation. It is particularly preferable that the molar ratio ([NCO] / [OH]) of the hydroxyl groups of the polyol to the isocyanate groups of the polyfunctional isocyanate mixture be in the range of 2 to 26.

[0041] In addition to the components described above, the two-component curing urethane adhesive may contain, as needed, a reaction catalyst used during the urethane extension of the polyester polyol and during the urethane curing reaction of the two-component curing urethane adhesive; a coupling agent, epoxy resin, or acrylic resin for improving adhesive strength; and various other known additives such as an antifoaming agent, a leveling agent, an ultraviolet absorber, or an antioxidant, added to the base resin or curing agent.

[0042] It is preferable to adopt a configuration in which the Young's modulus of the cured film of the two-component curing urethane adhesive is 90 MPa to 400 MPa. When the Young's modulus of the cured film is 90 MPa or more, the heat resistance of the outer adhesive layer 5 can be improved and delamination (peeling) between the outer layer 2 and the metal foil layer 4 can be more sufficiently prevented during heat sealing. When the Young's modulus of the cured film is 400 MPa or less, the adhesive strength of the outer adhesive can be more sufficiently ensured and high-temperature lamination strength can also be improved. Of these, it is more preferable that the Young's modulus of the cured film of the two-component curing urethane adhesive be 140 MPa to 300 MPa.

[0043] The thickness of the outer adhesive layer 5 is preferably set to 1 μm to 5 μm. In particular, from the viewpoint of reducing the thickness and weight of the exterior material, the thickness of the outer adhesive layer 5 is particularly preferably set to 1 μm to 3 μm.

[0044] In the present invention, the base layer (outer layer) 2 is preferably formed of a heat-resistant resin layer. The heat-resistant resin constituting the heat-resistant resin layer 2 is a heat-resistant resin that does not melt at the heat-sealing temperature when the packaging material 1 is heat-sealed. The heat-resistant resin preferably has a melting point 10°C or more higher than the melting point of the heat-fusible resin layer 3 (if the heat-fusible resin layer is formed of multiple layers, the melting point of the layer with the highest melting point), and it is particularly preferable to use a heat-resistant resin having a melting point 20°C or more higher than the melting point of the heat-fusible resin layer 3 (if the heat-fusible resin layer is formed of multiple layers, the melting point of the layer with the highest melting point).

[0045] The heat-resistant resin layer (outer layer) 2 is not particularly limited, but examples thereof include polyamide films such as nylon films, polyester films, etc., and oriented films thereof are preferably used. Among these, it is particularly preferred to use biaxially oriented polyamide films such as biaxially oriented nylon films, biaxially oriented polybutylene terephthalate (PBT) films, biaxially oriented polyethylene terephthalate (PET) films, or biaxially oriented polyethylene naphthalate (PEN) films as the heat-resistant resin layer 2. Examples of the nylon film include, but are not limited to, nylon 6 film, nylon 6,6 film, and MXD nylon film. The heat-resistant resin layer 2 may be formed as a single layer, or may be formed as a multilayer structure, for example, consisting of polyester film / polyamide film (e.g., a multilayer structure consisting of PET film / nylon film).

[0046] The thickness of the heat-resistant resin layer (outer layer) 2 is preferably 2 μm to 50 μm. When a polyester film is used, the thickness is preferably 2 μm to 50 μm, and when a nylon film is used, the thickness is preferably 7 μm to 50 μm. By setting the thickness equal to or greater than the above-mentioned preferable lower limit, sufficient strength as a packaging material can be ensured, and by setting the thickness equal to or less than the above-mentioned preferable upper limit, stress during molding such as stretch molding and draw molding can be reduced, thereby improving moldability.

[0047] The heat-sealable resin layer (inner layer) 3 provides excellent chemical resistance to highly corrosive electrolytes used in lithium ion secondary batteries and the like, and also plays a role in imparting heat sealability to the exterior packaging material.

[0048] The heat-sealable resin layer 3 is not particularly limited, but is preferably a heat-sealable resin non-stretched film layer. The heat-sealable resin non-stretched film layer 3 is not particularly limited, but is preferably composed of a non-stretched film made of at least one heat-sealable resin selected from the group consisting of polyethylene, polypropylene, olefin copolymers, acid-modified products thereof, and ionomers. The heat-sealable resin layer 3 may be a single layer or multiple layers.

[0049] The thickness of the heat-sealable resin layer 3 is preferably set to 10 μm to 80 μm. By setting the thickness to 10 μm or more, the occurrence of pinholes can be sufficiently prevented, and by setting the thickness to 80 μm or less, the amount of resin used can be reduced, thereby reducing costs. In particular, the thickness of the heat-sealable resin layer 3 is particularly preferably set to 25 μm to 50 μm.

[0050] A lubricant may be contained in the heat-sealable resin layer 3. The lubricant is not particularly limited, but a fatty acid amide is preferably used. The fatty acid amide is not particularly limited, but 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.

[0051] The metal foil layer 4 serves to impart gas barrier properties to the packaging material 1, preventing the intrusion of oxygen and moisture. The metal foil layer 4 is not particularly limited, but examples thereof include aluminum foil, SUS foil (stainless steel foil), copper foil, and nickel foil, with aluminum foil being commonly used. The thickness of the metal foil layer 4 is preferably 5 μm to 50 μm. A thickness of 5 μm or more can prevent the occurrence of pinholes during rolling in the production of the metal foil, while a thickness of 50 μm or less can reduce stress during forming such as stretch forming and drawing, thereby improving formability. Among these, a thickness of 10 μm to 30 μm is particularly preferred for the metal foil layer 4.

[0052] It is preferable that at least the inner surface (the surface on the second adhesive layer 6 side) of the metal foil layer 4 is subjected to a chemical conversion treatment. By performing such a chemical conversion treatment, corrosion of the metal foil surface due to the contents (such as the electrolyte of a battery) can be sufficiently prevented. For example, the chemical conversion treatment is performed on the metal foil by the following treatment. That is, for example, the surface of the metal foil that has been degreased is subjected to the following treatment. 1) phosphoric acid, Chromic acid, and at least one compound selected from the group consisting of metal salts of fluoride and non-metal salts of fluoride. 2) phosphoric acid, at least one resin selected from the group consisting of acrylic resins, chitosan derivative resins, and phenolic resins; and at least one compound selected from the group consisting of chromic acid and chromium (III) salts. 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 chromium (III) salts; and at least one compound selected from the group consisting of metal salts of fluoride and non-metal salts of fluoride. The chemical conversion treatment is carried out by applying an aqueous solution of any one of the above 1) to 3) and then drying it.

[0053] The chemical conversion coating has a chromium deposition amount (per side) of 0.1 mg / m 2 ~50mg / m 2 is preferred, and 2 mg / m 2 ~20mg / m 2 is preferred.

[0054] The inner adhesive layer 6 is not particularly limited, and although the adhesives exemplified above for the inner adhesive layer 5 can be used, it is preferable to use a polyolefin adhesive that is less likely to swell with an electrolyte. The thickness of the inner adhesive layer 6 is preferably set to 1 μm to 5 μm. In particular, from the viewpoint of reducing the thickness and weight of the exterior material, it is particularly preferable to set the thickness of the inner adhesive layer 6 to 1 μm to 3 μm.

[0055] An exterior case (battery case, etc.) 10 can be obtained by molding (deep drawing, stretch molding, etc.) the exterior material 1 for an electricity storage device of the present invention (see FIG. 3). Note that the exterior material 1 of the present invention can also be used as is without being subjected to molding (see FIG. 3).

[0056] FIG. 2 shows one embodiment of an electricity storage device 30 constructed using an exterior material 1 for an electricity storage device of the present invention. This electricity storage device 30 is a lithium-ion secondary battery. In this embodiment, as shown in FIGS. 2 and 3, an exterior member 15 is constructed by an exterior case 10 obtained by molding the exterior material 1 and a planar exterior material 1. A substantially rectangular parallelepiped electricity storage device main body 31 (such as an electrochemical element) is housed in a housing recess of the exterior case 10 obtained by molding the exterior material 1 of the present invention. The exterior material 1 of the present invention is placed on top of the electricity storage device main body 31 without being molded, with its heat-sealable resin layer 3 facing inward (lower), and the peripheral portion of the heat-sealable resin layer 3 of the planar exterior material 1 and the heat-sealable resin layer 3 of a flange portion (sealing peripheral portion) 29 of the exterior case 10 are heat-sealed and sealed to form the electricity storage device 30 of the present invention (see FIGS. 2 and 3). The inner surface of the storage recess of the exterior case 10 is made of a heat-sealable resin layer 3, and the outer surface of the storage recess is made of a base layer (outer layer) 2 (see FIG. 3).

[0057] 2, 39 denotes a heat-sealed portion where the peripheral edge of the exterior material 1 and the flange portion (sealing peripheral edge) 29 of the exterior case 10 are joined (welded) together. In the electricity storage device 30, the tip of a tab lead connected to the electricity storage device main body 31 is led out of the exterior member 15, but is not shown in the figure.

[0058] The electricity storage device main body 31 is not particularly limited, but examples thereof include a battery main body, a capacitor main body, and a condenser main body.

[0059] The width of the heat-sealed portion 39 is preferably set to 0.5 mm or more. By setting the width to 0.5 mm or more, sealing can be performed reliably. In particular, the width of the heat-sealed portion 39 is preferably set to 3 mm to 15 mm.

[0060] In the above embodiment, the exterior member 15 is configured to include an exterior case 10 obtained by molding the exterior material 1 and a planar exterior material 1 (see Figures 2 and 3), but is not limited to such a combination. For example, the exterior member 15 may be configured to include a pair of planar exterior materials 1, or a pair of exterior cases 10. [Example]

[0061] Next, specific examples of the present invention will be described, but the present invention is not particularly limited to these examples.

[0062] Example 1 A polyester polyol solution, the main component of a two-component curing urethane adhesive, was prepared. 30 moles of neopentyl glycol, 30 moles of ethylene glycol, and 40 moles of 1,6-hexanediol were melted at 80°C and stirred. A dicarboxylic acid mixture consisting of 40 moles of adipic acid, an aliphatic dicarboxylic acid, and 60 moles of isophthalic acid, an aromatic dicarboxylic acid, was subjected to a condensation polymerization reaction at 210°C for 20 hours to obtain a polyester polyol as the main component. This polyester polyol had a number-average molecular weight (Mn) of 15,000. 60 parts by weight of ethyl acetate was added to 40 parts by weight of the obtained polyester polyol (main component) and dissolved uniformly to obtain a polyester polyol solution with a solids content of 40% by weight and a hydroxyl value of 3.0 mgKOH / g (solution value).

[0063] A two-component curing urethane adhesive was obtained by blending 80 parts by weight of this polyester polyol solution with 6 parts by weight of an isocyanurate polyfunctional polyisocyanate solution of tolylene diisocyanate (TDI) as a curing agent (NCO content 7.6% by weight, solids content 50% by weight) and 14 parts by weight of an adduct polyisocyanate solution of xylylene diisocyanate (XDI) and trimethylolpropane as a curing agent (NCO content 11.9% by weight, solids content 75% by weight). In this two-component curing urethane adhesive, the polyol content of the solids (in the outer adhesive layer) was 70.3% by weight. Furthermore, in this two-component curing urethane adhesive, the solids content of the aromatic polyfunctional isocyanate in the total solids of the curing agent was 22.2% by weight, and the solids content of the "aliphatic polyfunctional isocyanate having an aromatic ring" in the total solids of the curing agent was 77.8% by weight.

[0064] Next, a chemical conversion treatment solution consisting of polyacrylic acid, a trivalent chromium compound, water, and alcohol was applied to both sides of a 35 μm thick aluminum foil (A8079 aluminum foil specified in JIS H4160) 4, and the resulting mixture was dried at 150° C. to prepare an aluminum foil with a chemical conversion coating on both sides. The chromium deposition amount of this chemical conversion coating was 5 mg / m on each side. 2 It was.

[0065] Next, the two-component curing urethane adhesive was applied to one side of the aluminum foil on both sides of which the chemical conversion coating had been formed, in an amount of 3.5 g / m after drying. 2 The aluminum foil 4 was coated on its other side with a 15 μm thick polyaxially oriented polyamide film (substrate layer) 2 and dried to form an outer adhesive layer 5, and a 15 μm thick biaxially oriented polyamide film (substrate layer) 2 was laminated to the surface of the outer adhesive layer 5. The other surface of the aluminum foil 4 was coated with a polyacrylic adhesive and dried to form an inner adhesive layer 6, and a 30 μm thick unstretched polypropylene film (heat-fusible resin layer) 3 was laminated to the surface of the inner adhesive layer 6. This laminate was left to stand (for aging) in a 40° C. environment for 9 days, thereby obtaining an exterior packaging material 1 for an electricity storage device having the configuration shown in FIG.

[0066] <Example 2> An exterior material for a power storage device 1 having the configuration shown in FIG. 1 was obtained in the same manner as in Example 1, except that 6 parts by mass of an isocyanurate multifunctional polyisocyanate solution of diphenylmethane diisocyanate (MDI) (NCO content 7.5% by mass, solid content 50% by mass) was used as the curing agent instead of 6 parts by mass of the isocyanurate multifunctional polyisocyanate solution of tolylene diisocyanate (TDI) in Example 1 (see Table 1).

[0067] Example 3 An exterior material for a power storage device 1 having the configuration shown in FIG. 1 was obtained in the same manner as in Example 1, except that, instead of 6 parts by mass of the isocyanurate polyfunctional polyisocyanate solution of tolylene diisocyanate (TDI) in Example 1, 3 parts by mass of an isocyanurate polyfunctional polyisocyanate solution of tolylene diisocyanate (TDI) (NCO content 7.6% by mass, solid content 50% by mass) and 3 parts by mass of an isocyanurate polyfunctional polyisocyanate solution of diphenylmethane diisocyanate (MDI) (NCO content 7.5% by mass, solid content 50% by mass) were used as the curing agent (see Table 1).

[0068] Example 4 An electrical storage device packaging material 1 having the configuration shown in FIG. 1 was obtained in the same manner as in Example 1, except that, instead of 6 parts by mass of the isocyanurate polyfunctional polyisocyanate solution of tolylene diisocyanate (TDI) and 14 parts by mass of the adduct polyisocyanate solution of xylylene diisocyanate (XDI) and trimethylolpropane in Example 1 as the curing agent, 4 parts by mass of an isocyanurate polyfunctional polyisocyanate solution of tolylene diisocyanate (TDI) (NCO content 7.6% by mass, solid content 50% by mass) and 16 parts by mass of an adduct polyisocyanate solution of xylylene diisocyanate (XDI) and trimethylolpropane as the curing agent (NCO content 11.9% by mass, solid content 75% by mass) were blended and stirred (see Table 1).

[0069] <Example 5> An electrical storage device packaging material 1 having the configuration shown in FIG. 1 was obtained in the same manner as in Example 1, except that, instead of 6 parts by mass of the isocyanurate polyfunctional polyisocyanate solution of tolylene diisocyanate (TDI) and 14 parts by mass of the adduct polyisocyanate solution of xylylene diisocyanate (XDI) and trimethylolpropane in Example 1 as the curing agent, 8 parts by mass of an isocyanurate polyfunctional polyisocyanate solution of tolylene diisocyanate (TDI) (NCO content 7.6% by mass, solid content 50% by mass) and 12 parts by mass of an adduct polyisocyanate solution of xylylene diisocyanate (XDI) and trimethylolpropane as the curing agent (NCO content 11.9% by mass, solid content 75% by mass) were blended and stirred (see Table 1).

[0070] Example 6 An exterior packaging material 1 for an electricity storage device having the configuration shown in FIG. 1 was obtained in the same manner as in Example 1, except that, instead of 6 parts by mass of the isocyanurate polyfunctional polyisocyanate solution of tolylene diisocyanate (TDI) and 14 parts by mass of the adduct polyisocyanate solution of xylylene diisocyanate (XDI) and trimethylolpropane in Example 1 as the curing agent, 10 parts by mass of an isocyanurate polyfunctional polyisocyanate solution of tolylene diisocyanate (TDI) (NCO content 7.6% by mass, solid content 50% by mass) and 10 parts by mass of an adduct polyisocyanate solution of xylylene diisocyanate (XDI) and trimethylolpropane as the curing agent (NCO content 11.9% by mass, solid content 75% by mass) were blended and stirred (see Table 1).

[0071] Example 7 An outer casing material 1 for a power storage device having the configuration shown in FIG. 1 was obtained in the same manner as in Example 1, except that a dicarboxylic acid mixture consisting of 65 molar parts of adipic acid, which is an aliphatic dicarboxylic acid, and 35 molar parts of isophthalic acid, which is an aromatic dicarboxylic acid, was used as the dicarboxylic acid mixture (see Table 1).

[0072] Example 8 An outer casing material 1 for an electricity storage device having the configuration shown in FIG. 1 was obtained in the same manner as in Example 1, except that a dicarboxylic acid mixture consisting of 55 molar parts of adipic acid, which is an aliphatic dicarboxylic acid, and 45 molar parts of isophthalic acid, which is an aromatic dicarboxylic acid, was used as the dicarboxylic acid mixture (see Table 1).

[0073] Example 9 An outer casing material 1 for an electricity storage device having the configuration shown in FIG. 1 was obtained in the same manner as in Example 1, except that a dicarboxylic acid mixture consisting of 20 molar parts of adipic acid, which is an aliphatic dicarboxylic acid, and 80 molar parts of isophthalic acid, which is an aromatic dicarboxylic acid, was used as the dicarboxylic acid mixture (see Table 1).

[0074] Example 10 An outer casing material 1 for an electricity storage device having the configuration shown in FIG. 1 was obtained in the same manner as in Example 1, except that a dicarboxylic acid mixture consisting of 15 molar parts of adipic acid, which is an aliphatic dicarboxylic acid, and 85 molar parts of isophthalic acid, which is an aromatic dicarboxylic acid, was used as the dicarboxylic acid mixture (see Table 1).

[0075] Example 11 An outer casing material 1 for a power storage device having the configuration shown in FIG. 1 was obtained in the same manner as in Example 1, except that a dicarboxylic acid mixture consisting of 10 molar parts of adipic acid, which is an aliphatic dicarboxylic acid, and 90 molar parts of isophthalic acid, which is an aromatic dicarboxylic acid, was used as the dicarboxylic acid mixture (see Table 1).

[0076] Example 12 An exterior material 1 for an electricity storage device having the configuration shown in FIG. 1 was obtained in the same manner as in Example 1, except that the compounding ratio of main agent (solution) / curing agent (solution) in the two-component curing urethane adhesive was changed to main agent (solution) / curing agent (solution) = 5 parts by mass / 35 parts by mass (see Table 1).

[0077] Example 13 An exterior material 1 for a power storage device having the configuration shown in FIG. 1 was obtained in the same manner as in Example 1, except that the compounding ratio of main agent (solution) / curing agent (solution) in the two-component curing urethane adhesive was changed to main agent (solution) / curing agent (solution) = 70 parts by mass / 30 parts by mass (see Table 1).

[0078] Example 14 An exterior material 1 for an electricity storage device having the configuration shown in FIG. 1 was obtained in the same manner as in Example 1, except that the compounding ratio of main agent (solution) / curing agent (solution) in the two-component curing urethane adhesive was changed to main agent (solution) / curing agent (solution) = 90 parts by mass / 10 parts by mass (see Table 1).

[0079] Example 15 An exterior material 1 for a power storage device having the configuration shown in FIG. 1 was obtained in the same manner as in Example 1, except that 80 parts by mass of the following polyether polyurethane polyol solution (referred to as "Polyol O" in Table 1) was used as the main agent (solution) instead of 80 parts by mass of the polyester polyol solution in Example 1 (see Table 1).

[0080] To prepare the polyether polyurethane polyol solution, 500 parts by mass of polytetramethylene ether glycol (hydroxyl value 112 mgKOH / g) as a polyether polyol and 82.2 parts by mass of tolylene diisocyanate were charged into a reaction vessel and reacted at 100°C for 7 hours with stirring to complete the reaction. After that, 388.1 parts by mass of ethyl acetate were added to obtain a polyether polyurethane polyol solution (solid content 40% by mass, number average molecular weight of polyether polyurethane polyol 14,500, hydroxyl value 3.1 mgKOH / g (solution value)).

[0081] Example 16 An exterior material 1 for a power storage device having the configuration shown in FIG. 1 was obtained in the same manner as in Example 1, except that 80 parts by mass of a polyester polyurethane polyol solution (referred to as "Polyol M" in Table 1) was used as the main agent (solution) instead of 80 parts by mass of the polyester polyol solution in Example 1 (see Table 1).

[0082] To prepare the polyester polyurethane polyol solution, first prepare a polyester polyol. 30 moles of neopentyl glycol, 30 moles of ethylene glycol, and 40 moles of 1,6-hexanediol were mixed and melted at 80°C. While stirring, a dicarboxylic acid mixture consisting of 40 moles of adipic acid (an aliphatic dicarboxylic acid) and 60 moles of isophthalic acid (an aromatic dicarboxylic acid) was subjected to a condensation polymerization reaction at 210°C for 20 hours to obtain a polyester polyol with a hydroxyl value of 56 mgKOH / g and an acid value of 0.4 mgKOH / g. Next, 500 parts by weight of the obtained polyester polyol and 39.2 parts by weight of tolylene diisocyanate were charged into a reaction vessel and reacted with stirring at 100°C for 7 hours to complete the reaction. After this, 359.4 parts by weight of ethyl acetate was added to obtain a polyester polyurethane polyol solution (solids content 40% by weight, polyester polyurethane polyol number average molecular weight 14,700, hydroxyl value 3.1 mgKOH / g (solution value)).

[0083] Example 17 An exterior material 1 for an electricity storage device having the configuration shown in FIG. 1 was obtained in the same manner as in Example 1, except that, instead of 14 parts by mass of the adduct polyisocyanate solution of xylylene diisocyanate (XDI) and trimethylolpropane in Example 1, 14 parts by mass of an adduct polyisocyanate solution of tetramethylxylylene diisocyanate (TMXDI) and trimethylolpropane (NCO content 10.2% by mass, solid content 75% by mass) was blended and stirred as a curing agent (aliphatic polyfunctional isocyanate having an aromatic ring).

[0084] <Comparative Example 1> An exterior material for an electricity storage device was obtained in the same manner as in Example 1, except that 20 parts by mass of an isocyanurate multifunctional polyisocyanate solution of diphenylmethane diisocyanate (MDI) (NCO content 7.5% by mass, solid content 50% by mass) was used as the curing agent instead of 6 parts by mass of the isocyanurate multifunctional polyisocyanate solution of tolylene diisocyanate (TDI) and 14 parts by mass of the adduct polyisocyanate solution of xylylene diisocyanate (XDI) and trimethylolpropane (see Table 1).

[0085] <Comparative Example 2> An exterior material for an electricity storage device was obtained in the same manner as in Example 1, except that 20 parts by mass of an isocyanurate multifunctional polyisocyanate solution of tolylene diisocyanate (TDI) (NCO content 7.6% by mass, solid content 50% by mass) was used as the curing agent instead of 6 parts by mass of the isocyanurate multifunctional polyisocyanate solution of tolylene diisocyanate (TDI) and 14 parts by mass of the adduct polyisocyanate solution of xylylene diisocyanate (XDI) and trimethylolpropane (see Table 1).

[0086] <Comparative Example 3> An exterior material for an electricity storage device was obtained in the same manner as in Example 1, except that 20 parts by mass of an adduct polyisocyanate solution of xylylene diisocyanate (XDI) and trimethylolpropane (NCO content 11.9% by mass, solid content 75% by mass) was used as the curing agent instead of 6 parts by mass of the isocyanurate polyfunctional polyisocyanate solution of tolylene diisocyanate (TDI) and 14 parts by mass of the adduct polyisocyanate solution of xylylene diisocyanate (XDI) and trimethylolpropane (see Table 1).

[0087] The Young's modulus of the cured film of the two-component curing urethane adhesive (outer adhesive) used in Examples 1 to 17 and Comparative Examples 1 to 3 is shown in Table 1. The Young's modulus was measured in accordance with JIS K7127-1999 (tensile test method for plastic films). Specifically, each outer adhesive was applied to a glass plate to a thickness of 50 μm, and then subjected to a heat aging treatment at 40°C for 11 days to thermally cure the outer adhesive, yielding a cured product with a thickness of 46 μm. The cured product was then peeled from the glass plate and cut into a size of 150 mm long, 10 mm wide, and 46 mm thick to prepare a test piece. A tensile test was performed at a tensile speed of 200 mm / min using a Shimadzu Access Strograph (tensile testing device) (AGS-5kNX) with an initial chuck distance of 100 mm and a gauge length of 50 mm to determine the Young's modulus (MPa).

[0088] [Table 1]

[0089] [Table 2]

[0090] Each of the packaging materials for an electricity storage device obtained as described above was evaluated according to the following evaluation methods. The results are shown in Table 2.

[0091] <Yellowing resistance evaluation method> An electrical storage device exterior material was immersed in an electrolyte solution prepared by dissolving lithium hexafluorophosphate (LiPF6) at a concentration of 1000 ppm in a mixed solvent of equal volumetric ratios of ethylene carbonate (EC) and dimethyl carbonate (DMC), and then stored at 45°C for 24 hours. The electrical storage device exterior material was then removed, washed with water, and dried. The Lab value of the dried electrical storage device exterior material from the outer layer side was measured using a Konica Minolta CM-2500C color-difference colorimeter, and the b value was used as a criterion for determining the degree of yellowing, and the material was evaluated based on the following criteria. The higher the b value, the deeper the yellow color. (Judgment criteria) "◎"...b value is 1.0 or less (pass) "○": b value is greater than 1.0 and less than 2.0 (pass) "×"...b value is greater than 2.0.

[0092] <Formability evaluation method> Using a depth-free straight mold, the exterior material was subjected to one-stage deep drawing under the following molding conditions, and formability was evaluated for each forming depth (9.0 mm, 8.5 mm, 8.0 mm, 7.5 mm, 7.0 mm, 6.5 mm, 6.0 mm, 5.5 mm, 5.0 mm, 4.5 mm, 4.0 mm, 3.5 mm, 3.0 mm, 2.5 mm, 2.0 mm). The maximum forming depth (mm) at which good forming could be achieved with no pinholes at the corners was determined, and formability was evaluated based on the following criteria. The presence or absence of pinholes was determined by visually observing the presence or absence of transmitted light passing through the pinholes. (Molding conditions) Mold...Punch: 33.3mm x 53.9mm, Die: 80mm x 120mm, Corner R: 2mm, Punch R: 1.3mm, Die R: 1mm Wrinkle holding pressure...Gauge pressure: 0.475 MPa, Actual pressure (calculated value): 0.7 MPa Material: SC (carbon steel), punch R only chrome plated. (Judgment criteria) "◎": The maximum molding depth without pinholes or cracks is 7.0 mm or more (passed) "○": The maximum molding depth without pinholes or cracks is 5.0 mm or more and less than 7.0 mm (passed). "X": The maximum forming depth at which pinholes and cracks do not occur is less than 5.0 mm.

[0093] <Hot lamination strength evaluation method> A test specimen measuring 15 mm wide x 150 mm long was cut out from the obtained exterior material for a storage battery device, and the test specimen was held in a temperature environment of 120°C for 1 minute. After that, in accordance with JIS K6854-3 (1999), a T-type peel was performed between the outer layer 2 and the metal foil layer 4 at a tensile speed of 100 mm / min using a Strograph (tensile testing device) (AGS-5kNX) manufactured by Shimadzu Access Co., Ltd., and the peel strength was measured. This was taken as the hot lamination strength (N / 15 mm width) and evaluated based on the following criteria. (Judgment criteria) "◎": Hot lamination strength is "2.0N / 15mm width" or more (passed) "○": Hot lamination strength is "1.5N / 15mm width" or more and less than "2.0N / 15mm width" (passed) "△": Hot lamination strength is "1.0N / 15mm width" or more and less than "1.5N / 15mm width" (pass) "X": Hot lamination strength is less than "1.0 N / 15 mm width".

[0094] <Seal resistance evaluation method> The exterior material was subjected to a single-stage deep-draw molding process to a depth of 5.0 mm using a depth-free straight mold, and then the peripheral edges of a pair of molded products were overlapped so that the inner layers of each were in contact. Using a heat-sealing device (TP-701-A) manufactured by Tester Sangyo Co., Ltd., the product was heat-sealed by heating on one side at a heat-sealing temperature of 170°C, a sealing pressure of 0.2 MPa (gauge pressure), and a sealing time of 6 seconds. The appearance of the heat-sealed product was visually inspected for the presence and length of any lifting or delamination (peeling) between the outer layer and the metal foil layer of the heat-sealed product, and the sealability was evaluated based on the following criteria. (Judgment criteria) "◎": No lifting or delamination (passed) "○": The length of the lifted or delaminate area is over 0 mm and 2 mm or less (passed) "△": The length of the lifted or delaminate area is over 2 mm and 4 mm or less (passed) "X": The length of the lifted or delaminate area is longer than 4 mm.

[0095] As is clear from the table, the packaging materials for electricity storage devices of Examples 1 to 17 of the present invention were excellent in yellowing resistance, ensured good formability, had sufficient hot lamination strength, and also had good sealing resistance.

[0096] In contrast, Comparative Examples 1 and 2, in which aromatic polyfunctional isocyanate was used alone as the curing agent, exhibited poor yellowing resistance, and Comparative Example 3, in which aliphatic polyfunctional isocyanate having an aromatic ring was used alone as the curing agent, exhibited poor moldability. [Industrial Applicability]

[0097] Specific examples of the packaging material for an electricity storage device according to the present invention include: - Energy storage devices such as lithium secondary batteries (lithium ion batteries, lithium polymer batteries, etc.) Lithium-ion capacitor Electric double layer capacitor The electric storage device according to the present invention is used as an exterior material for various electric storage devices such as the above-mentioned electric storage devices. In addition, the electric storage device according to the present invention also includes all-solid-state batteries. [Explanation of symbols]

[0098] 1...Exterior materials for energy storage devices 2...Base material layer (outer layer) 3…Thermofusible resin layer (inner layer) 4…Metal foil layer 5…Outer adhesive layer 10...Outer case 15...Exterior material 30...Electricity storage device 31...electricity storage device main body

Claims

1. An exterior packaging material for an electricity storage device, comprising: a base material layer as an outer layer; a heat-sealable resin layer as an inner layer; and a metal foil layer disposed between these layers, the substrate layer and the metal foil layer are bonded via an outer adhesive layer, the outer adhesive layer is formed of a cured film of a two-component curing urethane adhesive, the outer adhesive layer including a base agent containing a polyol and a polyfunctional isocyanate mixture; the polyfunctional isocyanate mixture is a mixture containing an aromatic polyfunctional isocyanate and an aliphatic polyfunctional isocyanate having an aromatic ring, An exterior material for an electricity storage device, characterized in that the isocyanate group (-NCO) of the polyfunctional isocyanate mixture is blended in a ratio of 1 mole to 30 moles per mole of hydroxyl group (-OH) of the polyol.

2. The content of the aromatic polyfunctional isocyanate in the polyfunctional isocyanate mixture is 5% by mass to 40% by mass, and the content of the aliphatic polyfunctional isocyanate having an aromatic ring in the polyfunctional isocyanate mixture is 60% by mass to 95% by mass.

2. The electrical storage device packaging material according to claim 1,

3. the polyol is a polyester polyol, The polyester polyol contains a dicarboxylic acid component, 3. The electrical storage device packaging material according to claim 1, wherein the dicarboxylic acid component contains an aromatic dicarboxylic acid, and the content of the aromatic dicarboxylic acid in the dicarboxylic acid component is 35 mol% to 90 mol%.

4. The packaging material for an electricity storage device according to any one of claims 1 to 3, wherein the aliphatic polyfunctional isocyanate having an aromatic ring is one or more isocyanates selected from the group consisting of xylylene diisocyanate and modified products thereof.

5. An exterior case for an electricity storage device, comprising a molded article of the exterior material for an electricity storage device according to any one of claims 1 to 4.

6. a power storage device main body; The electrical storage device packaging material according to any one of claims 1 to 4 and the electrical storage device packaging case according to claim 5 are provided with one or two packaging members selected from the group consisting of: The power storage device, wherein the power storage device main body is sheathed with the sheathing member.

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