JP2017059388A - Jacket material for power storage device and power storage device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a jacket material for a power storage device excellent in deep drawing moldability and a power storage device using the same.SOLUTION: The jacket material includes a structure in which at least a substrate layer, an adhesive layer, a metal foil layer, sealant adhesive layer, and sealant layer are laminated in this order. The substrate layer is made of a polyester film containing greater than or equal to 12% of ΔA shown by the following formula (1) and having the stress value when being extended by 50% after heat treatment at 200°C is greater than or equal to 75 MPa. ΔA=(fracture elongation after heat treatment at 200°C)-(fracture elongation after heat treatment at 160°C) ...(1)SELECTED DRAWING: Figure 1

Description

  The present invention relates to a power storage device exterior material and a power storage device using the same.

  As power storage devices, for example, secondary batteries such as lithium ion batteries, nickel metal hydride batteries, and lead storage batteries, and electrochemical capacitors such as electric double layer capacitors are known. There is a demand for further miniaturization of power storage devices due to miniaturization of portable devices or limitations on installation space, and lithium ion batteries with high energy density are attracting attention. Conventionally, metal cans have been used as exterior materials used in lithium ion batteries, but multilayer films that are lightweight, have high heat dissipation properties, and can be manufactured at low cost are being used.

  In a lithium ion battery using the multilayer film as an exterior material, the battery contents (positive electrode, separator, negative electrode, electrolyte, etc.) are covered with an exterior material including an aluminum foil layer in order to prevent moisture from entering the interior. It has been adopted. A lithium ion battery employing such a configuration is called an aluminum laminate type lithium ion battery.

  An aluminum laminate type lithium ion battery, for example, forms a recess in a part of the exterior material by cold molding, accommodates the battery contents in the recess, folds the remaining part of the exterior material, and heats the edge portion. An embossed type lithium ion battery sealed with a seal is known. (For example, refer to Patent Document 1). In such a lithium ion battery, the deeper the recess formed by cold forming, the more battery contents can be accommodated, so the energy density can be increased.

JP 2013-101765 A

  However, when an exterior material for a power storage device is manufactured according to the material and the manufacturing method described in Patent Document 1 and a deep recess is formed in the exterior material, the exterior material may be broken. Therefore, an object of the present invention is to provide an exterior material for a power storage device that is excellent in deep drawability and a power storage device using the same.

In order to achieve the above object, the present invention has a structure in which at least a base material layer, an adhesive layer, a metal foil layer, a sealant adhesive layer, and a sealant layer are laminated in this order. Provided is a power storage device exterior material, which is a layer made of a polyester film having a ΔA shown in 1) of 12% or more and a 50% elongation stress value after heat treatment at 200 ° C. of 75 MPa or more.
ΔA = (breaking elongation after heat treatment at 200 ° C.) − (Breaking elongation after heat treatment at 160 ° C.) (1)
However, the elongation at break and the stress value at 50% elongation are respectively tensile tests (test piece shape: JIS) with respect to the four directions (0 ° (MD), 45 °, 90 ° (TD), 135 °) of the base material layer. No. 5 type dumbbell shape defined in K7127, distance between chucks: 75 mm, distance between gauge points: 25 mm, test speed: 50 mm / min).

  In a manufacturing process of a power storage device exterior material, there is a process that requires a laminating process in order to stack a plurality of layers. At this time, in general, the base material layer may be thermally deteriorated by heat applied at the time of lamination or heat applied at the time of drying the adhesive, and tearing may occur when the drawing is performed. On the other hand, in the case of a base material layer that is so rigid that it hardly causes thermal degradation due to heat applied during lamination or heat applied during drying of the adhesive, there is a possibility that tearing may occur when the drawing is performed. The present invention solves these problems and can exhibit excellent deep drawability regardless of the manufacturing process of the exterior material.

  It is preferable that the power storage device exterior material further includes an easy adhesion treatment layer provided between the base material layer and the adhesive layer. Thereby, while being able to improve the adhesiveness between a base material layer and a contact bonding layer, deep drawing moldability can be improved more.

  In the power storage device exterior material, the easy adhesion treatment layer may be a layer containing at least one resin selected from the group consisting of a polyester resin, an acrylic resin, a polyurethane resin, an epoxy resin, and an acrylic graft polyester resin. preferable. Thereby, while being able to improve the adhesiveness between a base material layer and a contact bonding layer, deep drawing moldability can be improved more.

  The power storage device exterior material preferably further includes a corrosion prevention treatment layer provided on both surfaces of the metal foil layer. Thereby, the adhesiveness between a base material layer and a metal foil layer can be improved more.

  In the exterior material for a power storage device, it is preferable that the corrosion prevention treatment layer includes a rare earth element oxide and phosphoric acid or a phosphate. Thereby, the adhesiveness between a base material layer and a metal foil layer can be improved more.

  In the power storage device exterior material, the rare earth element oxide is preferably cerium oxide. Thereby, the adhesiveness between a base material layer and a metal foil layer can be improved more.

  The present invention also includes a battery element including an electrode, a lead extending from the electrode, and a container that sandwiches the lead and accommodates the battery element, and the container includes the outer packaging material for a power storage device of the present invention. Thus, a power storage device is provided in which the sealant layer is formed on the inner side. In such a power storage device, since the power storage device exterior material of the present invention is used as a container for accommodating battery elements, a deep recess can be formed in the container without causing breakage or the like.

  ADVANTAGE OF THE INVENTION According to this invention, the exterior material for electrical storage apparatuses excellent in deep drawing moldability, and an electrical storage apparatus using the same can be provided. More specifically, according to the present invention, excellent deep drawability can be exhibited regardless of the exterior material manufacturing process.

It is a schematic sectional drawing of the exterior material for electrical storage apparatuses which concerns on one Embodiment of this invention. It is a figure which shows the embossing type exterior material obtained using the exterior material for electrical storage devices which concerns on one Embodiment of this invention, (a) is the perspective view, (b) is the embossing shown to (a). It is a longitudinal cross-sectional view along the bb line of the type exterior material. It is a perspective view which shows the process of manufacturing a secondary battery using the exterior material for electrical storage devices which concerns on one Embodiment of this invention, (a) shows the state which prepared the exterior material for electrical storage devices, (b) Is a state in which an exterior material for a power storage device processed into an embossed type and a battery element are prepared, and (c) is a state in which a part of the exterior material for a power storage device is folded and an end is melted. ) Shows a state where both sides of the folded portion are folded upward.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant description is omitted.

[Exterior material for power storage devices]
FIG. 1 is a cross-sectional view schematically showing an embodiment of an exterior material for a power storage device of the present invention. As shown in FIG. 1, an exterior material (exterior material for a power storage device) 10 of this embodiment includes a base material layer 11, an easy adhesion treatment layer 12 provided on one surface side of the base material layer 11, An adhesive layer 13 provided on the side opposite to the base material layer 11 of the easy adhesion treatment layer 12 and a corrosion prevention treatment layer 15a on both sides provided on the opposite side of the easy adhesion treatment layer 12 of the adhesive layer 13 And 15b, a sealant adhesive layer 16 provided on the opposite side of the adhesive layer 13 of the metal foil layer 14, and a metal foil layer 14 provided on the opposite side of the sealant adhesive layer 16. The sealant layer 17 is sequentially laminated. Here, the corrosion prevention treatment layer 15a is provided on the surface of the metal foil layer 14 on the adhesive layer 13 side, and the corrosion prevention treatment layer 15b is provided on the surface of the metal foil layer 14 on the sealant adhesion layer 16 side. In the exterior material 10, the base material layer 11 is the outermost layer and the sealant layer 17 is the innermost layer. That is, the exterior material 10 is used with the base material layer 11 facing the outside of the power storage device and the sealant layer 17 facing the inside of the power storage device. Hereinafter, each layer will be described.

(Base material layer 11)
The base material layer 11 provides the exterior material 10 with heat resistance in a pressurization heat fusion process, which will be described later in manufacturing the power storage device, and resistance to the electrolyte solution leaked from the other power storage device. This is a layer for suppressing the generation of pinholes that may occur during distribution. The base material layer is a layer made of a polyester film having ΔA represented by the following formula (1) of 12% or more and a 50% elongation stress value (F50 stress value) after heat treatment at 200 ° C. of 75 MPa or more. It is.
ΔA = (breaking elongation after heat treatment at 200 ° C.) − (Breaking elongation after heat treatment at 160 ° C.) (1)

In the present embodiment, the elongation at break and the stress value at 50% elongation are values defined as follows. That is, after heating the base material layer cut into A4 size for 30 minutes in an oven maintained at an arbitrary heat treatment temperature (160 ° C. or 200 ° C.), the four directions of the base material layer (0 ° (MD), 45 °, 90 ° (TD), 135 °) vs. tensile test at 23 ° C (room temperature) (Test piece shape: No. 5 type dumbbell as defined in JIS K7127, Chuck distance: 75 mm, Between marks Distance: 25 mm, test speed: 50 mm / min). And the fracture | rupture elongation in this embodiment and the stress value at the time of 50% elongation are calculated by taking the average of the measurement result with respect to 4 directions. The elongation at break is a value calculated as follows.
Elongation at break (%) = {(Distance between gauge points at break−Distance between gauge points before measurement) / Distance between gauge points before measurement} × 100

  In addition, the vertical direction and the horizontal direction of a base material layer shall be matched with MD direction (machine feed direction) and TD direction (perpendicular direction of MD direction) of a base material layer original fabric, respectively. That is, when the base material layer 11 consists of a biaxially stretched film, the vertical direction and the horizontal direction of a test piece correspond to either one of the two extending directions of a film, respectively.

  In the exterior material 10, since the above ΔA is 12% or more, even when the base material layer 11 is easily stretched with a smaller force due to heat of heat treatment, it is difficult to break. Can be made possible. From this viewpoint, ΔA is preferably 14% or more, and more preferably 16% or more. The upper limit of ΔA is not particularly limited, but if the base material layer 11 is easily stretched and the stress value at 50% elongation becomes too small, it is difficult to play a role of protecting the metal foil layer 14 from molding stress. From the viewpoint of becoming, it can be about 100%.

  Moreover, in the exterior material 10, when the stress value at the time of 50% elongation after heat treatment at 200 ° C. is 75 MPa or more, the force when a local force is applied to the exterior material 10 can be dispersed, The metal foil layer 14 can be prevented from breaking when it is drawn. From this viewpoint, the stress value at 50% elongation is preferably 80 MPa or more, and more preferably 85 MPa or more. The upper limit of the 50% elongation stress value is not particularly limited, but can be about 250 MPa from the viewpoint of being molded and used.

  The polyester resin constituting the polyester film of the base material layer 11 can be used without particular limitation as long as it can satisfy the above characteristics. For example, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate. And copolyester. Among these, from the viewpoint of excellent deep drawability, a copolymerized polyester can be suitably used.

  As the polyester film, any one obtained by any of the simultaneous stretching method and the biaxial stretching method can be used, but from the viewpoint of obtaining a better deep drawing moldability, it may be a biaxially stretched polyester film. preferable.

  Examples of the stretching method for the biaxially stretched film include a sequential biaxial stretching method, a tubular biaxial stretching method, and a simultaneous biaxial stretching method. The biaxially stretched film is preferably stretched by a tubular biaxial stretching method and a simultaneous biaxial stretching method from the viewpoint of obtaining better deep drawability.

  The thickness of the base material layer 11 is preferably 6 to 40 μm, and more preferably 10 to 30 μm. When the thickness of the base material layer 11 is 6 μm or more, there is a tendency that the pinhole resistance and the insulating property of the power storage device exterior material 10 can be improved. If the thickness of the base material layer 11 exceeds 40 μm, the total thickness of the power storage device exterior material 10 becomes large, which is not desirable because the electric capacity of the battery may have to be reduced.

(Easy adhesion treatment layer 12)
The easy adhesion treatment layer 12 is provided on one surface side of the base material layer 11 and is disposed between the base material layer 11 and the adhesive layer 13. The easy adhesion treatment layer 12 is a layer for improving the adhesiveness between the base material layer 11 and the adhesive layer 13 and thus improving the adhesiveness between the base material layer 11 and the metal foil layer 14. In the power storage device exterior material 10, the easy adhesion treatment layer 12 may not be provided. In that case, in order to improve the adhesiveness between the base material layer 11 and the adhesive layer 13, and consequently improve the adhesiveness between the base material layer 11 and the metal foil layer 14, the adhesive layer of the base material layer 11 is used. The 13th surface may be corona treated.

  The easy adhesion treatment layer 12 is preferably a layer containing at least one resin selected from the group consisting of a polyester resin, an acrylic resin, a polyurethane resin, an epoxy resin, and an acrylic graft polyester resin. The easy-adhesion treatment layer 12 is made of, for example, at least one resin selected from the group consisting of a polyester resin, an acrylic resin, a polyurethane resin, an epoxy resin, and an acrylic graft polyester resin on one surface of the base material layer 11. It can be formed by applying a coating agent as a main component.

<Polyester resin>
As the polyester resin, a copolymer polyester in which a copolymer component is introduced to lower the glass transition temperature is preferable from the viewpoint of adhesiveness. The copolymer polyester preferably has water solubility or water dispersibility from the viewpoint of coatability. As such a copolyester, a copolyester in which at least one group selected from the group consisting of sulfonic acid groups or alkali metal bases thereof is bonded (hereinafter referred to as “sulfonic acid group-containing copolyester”) is used. It is preferable to use it.

  Here, the sulfonic acid group-containing copolymer polyester means a polyester in which at least one group selected from the group consisting of a sulfonic acid group or an alkali metal base thereof is bonded to a part of a dicarboxylic acid component or a glycol component, , A copolymer prepared using an aromatic dicarboxylic acid component containing at least one group selected from the group consisting of sulfonic acid groups or alkali metal bases thereof in a proportion of 2 to 10 mol% based on the total acid components Polyester is preferred.

  As an example of such a dicarboxylic acid, 5-sodium sulfoisophthalic acid is suitable. In this case, as other dicarboxylic acid components, terephthalic acid, isophthalic acid, phthalic acid, p-β-oxyethoxybenzoic acid, 2,6-naphthalenedicarboxylic acid, 4,4′-dicarboxydiphenyl, 4,4 ′ -Dicarboxybenzophenone, bis (4-carboxyphenyl) ethane, adipic acid, sebacic acid, cyclohexane-1,4-dicarboxylic acid and the like.

  As the glycol component for producing the sulfonic acid group-containing copolymer polyester, ethylene glycol is mainly used. In addition, addition of propylene glycol, butanediol, neopentyl glycol, diethylene glycol, cyclohexanedimethanol, bisphenol A ethylene oxide addition Products, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and the like can be used. Among them, it is preferable to use ethylene glycol, propylene glycol, butanediol, neopentyl glycol, diethylene glycol, cyclohexane dimethanol or the like as a copolymerization component in terms of improving compatibility with polystyrene sulfonate.

  In addition, as the polyester resin, a modified polyester copolymer, for example, a block copolymer modified with polyester, urethane, epoxy, or the like, a graft copolymer, or the like may be used. In the present embodiment, in order to improve the adhesion between the easy adhesion treatment layer 12 and the base material layer 11 and the adhesion layer 13, the easy adhesion treatment layer 12 may further contain a resin other than the polyester resin. Examples of such a resin include a urethane resin and an acrylic resin.

<Acrylic resin>
Examples of the monomer component constituting the acrylic resin include alkyl acrylate, alkyl methacrylate (alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, 2 -Ethylhexyl group, lauryl group, stearyl group, cyclohexyl group, phenyl group, benzyl group, phenylethyl group and the like); 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl Hydroxyl group-containing monomers such as methacrylate; acrylamide, methacrylamide, N-methylacrylamide, N-methylmethacrylamide, N-methylolacrylamide, N-methylolmethacrylamide, N, N Amide group-containing monomers such as dimethylolacrylamide, N-methoxymethylacrylamide, N-methoxymethylmethacrylamide and N-phenylacrylamide; amino group-containing monomers such as N, N-diethylaminoethyl acrylate and N, N-diethylaminoethyl methacrylate; Epoxy group-containing monomers such as glycidyl acrylate and glycidyl methacrylate; carboxyl groups such as acrylic acid, methacrylic acid and salts thereof (lithium salt, sodium salt, potassium salt, etc.), or monomers containing such salts can be used. . These may be used individually by 1 type, and may be copolymerized using 2 or more types. Furthermore, these can be used in combination with other monomers other than those described above.

  Other monomers include, for example, epoxy group-containing monomers such as allyl glycidyl ether; sulfonic acid groups such as styrene sulfonic acid, vinyl sulfonic acid and salts thereof (lithium salt, sodium salt, potassium salt, ammonium salt, etc.) Monomers containing salts; Monomers containing carboxyl groups or salts thereof such as crotonic acid, itaconic acid, maleic acid, fumaric acid, and salts thereof (lithium salt, sodium salt, potassium salt, ammonium salt, etc.); maleic anhydride Monomers containing acid anhydrides such as acid and itaconic anhydride; vinyl isocyanate, allyl isocyanate, styrene, vinyl methyl ether, vinyl ethyl ether, vinyl trisalkoxysilane, alkyl maleic acid monoester, alkyl fumaric acid monoe Ether, acrylonitrile, methacrylonitrile, alkyl itaconic acid monoester, vinylidene chloride, vinyl acetate, etc. can be used vinyl chloride. In addition, as the acrylic resin, a modified acrylic copolymer, for example, a block copolymer modified with polyester, urethane, epoxy, or the like, a graft copolymer, or the like may be used.

  The glass transition point (Tg) of the acrylic resin used in the present embodiment is not particularly limited, but is preferably 0 to 90 ° C, more preferably 10 to 80 ° C. If the Tg is low, the adhesiveness under high temperature and high humidity may decrease, and if it is high, cracks may occur during stretching. From the viewpoint of suppressing them, the Tg of the acrylic resin is within the above range. Is preferred.

  In addition, the weight average molecular weight of the acrylic resin used in the present embodiment is preferably 100,000 or more, and more preferably 300,000 or more. If the weight average molecular weight is low, the heat-and-moisture resistance may decrease. In the present embodiment, in order to improve the adhesion between the easy adhesion treatment layer 12 and the base material layer 11 and the adhesion layer 13, the easy adhesion treatment layer 12 may further contain a resin other than an acrylic resin. Examples of such a resin include a polyester resin and a urethane resin.

<Polyurethane resin>
As the polyurethane resin, an aqueous polyurethane resin is preferable. The water-based polyurethane resin is preferably a self-emulsifying type from the viewpoint of small particle size and good stability. The particle diameter of the water-based polyurethane resin is preferably about 10 to 100 nm. As for the water-based polyurethane resin used for this embodiment, it is desirable that the glass transition point (Tg) is 40 to 150 degreeC. When Tg is 40 ° C. or higher, there is a tendency that it is possible to sufficiently suppress the occurrence of blocking when winding into a roll after coating. On the other hand, if the Tg is too higher than the drying temperature after coating, it is difficult to form a uniform film. Therefore, the Tg is preferably 150 ° C. or lower.

  In the present embodiment, a crosslinking agent may be used together with the water-based polyurethane resin. As a water-based polyurethane crosslinking agent, a general-purpose water-soluble crosslinking agent such as a water-soluble epoxy compound can be used. A water-soluble epoxy compound is a compound having solubility in water and having two or more epoxy groups. Examples of the water-soluble epoxy compound include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, 1,4-butanediol, 1,6-hexanediol, neo Polyepoxy compounds obtained by etherification of 1 mol of glycols such as pentyl glycol and 2 mol of epichlorohydrin, and esters of 1 mol of dicarboxylic acids such as phthalic acid, terephthalic acid, adipic acid and oxalic acid and 2 mol of epichlorohydrin And diepoxy compounds obtained by the conversion. However, the water-soluble epoxy compound is not limited to these.

  These water-soluble crosslinking agents crosslink with the water-based polyurethane resin, improve the water resistance and solvent resistance of the coating film, and improve the adhesion between the easy adhesion treatment layer 12 and the base material layer 11 and the adhesive layer 13. Contribute. In this embodiment, in order to improve the adhesiveness between the easily bonding process layer 12, the base material layer 11, and the contact bonding layer 13, you may further contain resin other than a urethane resin. Examples of such a resin include a polyester resin and an acrylic resin.

  The easy adhesion treatment layer 12 may include, for example, the resin as the main component and a curing agent such as a polyfunctional isocyanate, a polyfunctional glycidyl compound, or a melamine compound. As described above, by including the above-mentioned resin as a main component and a curing agent such as a polyfunctional isocyanate, a polyfunctional glycidyl compound, or a melamine compound, it is possible to incorporate a cross-linked structure, so it is hard and easy to adhere. The treatment layer 12 can be configured.

  The coating agent used to form the easy adhesion treatment layer 12 may be a solvent system or an aqueous system. A dispersion type (dispersion) using an aqueous main agent has a large molecular weight, improves intermolecular cohesion, and is effective for adhesion between the easy adhesion treatment layer 12, the base material layer 11, and the adhesive layer 13. is there.

  The thickness of the easy adhesion treatment layer 12 is preferably 0.02 to 0.5 μm, and more preferably 0.04 to 0.3 μm. When the thickness of the easy adhesion treatment layer 12 is 0.02 μm or more, it is easy to form a uniform easy adhesion treatment layer 12 and a more sufficient easy adhesion effect tends to be obtained. On the other hand, when the thickness of the easy adhesion treatment layer 12 is 0.5 μm or less, the deep drawability of the exterior material 10 tends to be further improved.

(Adhesive layer 13)
The adhesive layer 13 is a layer that bonds the base material layer 11 and the metal foil layer 14 together. The adhesive layer 13 is bonded to the base material layer 11 via the easy adhesion treatment layer 12. The adhesive layer 13 has an adhesive force necessary for firmly bonding the base material layer 11 and the metal foil layer 14, and the metal foil layer 14 is broken by the base material layer 11 during cold forming. It also has follow-up property for suppressing this (performance for reliably forming the adhesive layer 13 on the member without peeling even if the member is deformed / stretched).

  As an adhesive constituting the adhesive layer 13, for example, a two-part liquid having a main agent made of a polyol such as polyester polyol, polyether polyol, acrylic polyol, and a curing agent made of an aromatic or aliphatic isocyanate. A curable polyurethane adhesive can be used. In the above adhesive, the molar ratio of the isocyanate group of the curing agent to the hydroxyl group of the main agent (= NCO / OH) is preferably 1 to 10, and more preferably 2 to 5.

  For example, the polyurethane adhesive is subjected to aging at 40 ° C. for 4 days or more after coating, whereby the reaction between the hydroxyl group of the main agent and the isocyanate group of the curing agent proceeds, whereby the base material layer 11 and the metal foil layer 14. It becomes possible to bond more firmly.

  The thickness of the adhesive layer 13 is preferably 1 to 10 μm and more preferably 2 to 6 μm from the viewpoint of obtaining desired adhesive strength, followability, workability, and the like.

(Metal foil layer 14)
Examples of the metal foil layer 14 include various metal foils such as aluminum and stainless steel, and the metal foil layer 14 is preferably an aluminum foil from the viewpoint of workability such as moisture resistance and spreadability, and cost. The aluminum foil may be a general soft aluminum foil, but is preferably an aluminum foil containing iron from the viewpoint of excellent pinhole resistance and extensibility during molding.

  In the aluminum foil containing iron (100% by mass), the iron content is preferably 0.1 to 9.0% by mass, and more preferably 0.5 to 2.0% by mass. When the iron content is 0.1% by mass or more, it is possible to obtain the exterior material 10 having more excellent pinhole resistance and spreadability. When the iron content is 9.0% by mass or less, it is possible to obtain the exterior material 10 having more flexibility.

  The aluminum foil is more preferably a soft aluminum foil subjected to an annealing treatment (for example, aluminum foil made of 8021 material and 8079 material according to JIS standards) from the viewpoint of imparting desired extensibility during molding.

  The metal foil used for the metal foil layer 14 is preferably subjected to a degreasing treatment, for example, in order to obtain a desired electrolytic solution resistance. In order to simplify the production process, the metal foil is preferably one whose surface is not etched. As the degreasing process, for example, a wet type degreasing process or a dry type degreasing process can be used, but a dry type degreasing process is preferable from the viewpoint of simplifying the manufacturing process.

  Examples of the dry-type degreasing treatment include a method of performing the degreasing treatment by increasing the treatment time in the step of annealing the metal foil. In the annealing treatment performed to soften the metal foil, sufficient electrolytic solution resistance can be obtained even with the degreasing treatment performed simultaneously.

  In addition, as the dry type degreasing treatment, a treatment such as a frame treatment or a corona treatment which is a treatment other than the annealing treatment may be used. Further, as the dry type degreasing treatment, for example, a degreasing treatment in which contaminants are oxidatively decomposed and removed by active oxygen generated when the metal foil is irradiated with ultraviolet rays having a specific wavelength may be used.

  As the wet type degreasing treatment, for example, treatments such as acid degreasing treatment and alkali degreasing treatment can be used. Examples of the acid used for the acid degreasing treatment include inorganic acids such as sulfuric acid, nitric acid, hydrochloric acid, and hydrofluoric acid. These acids may be used individually by 1 type, and may use 2 or more types together. Moreover, as an alkali used for an alkali degreasing process, sodium hydroxide with a high etching effect can be used, for example. Moreover, you may perform an alkaline degreasing process using the material with which the weak alkali type material, surfactant, etc. were mix | blended. The wet type degreasing treatment described above can be performed, for example, by an immersion method or a spray method.

  The thickness of the metal foil layer 14 is preferably 9 to 200 μm, more preferably 15 to 150 μm, and further preferably 15 to 100 μm from the viewpoint of barrier properties, pinhole resistance, and workability. preferable. When the thickness of the metal foil layer 14 is 9 μm or more, the metal foil layer 14 is hardly broken even when stress is applied by molding. When the thickness of the metal foil layer 14 is 200 μm or less, an increase in mass of the exterior material can be reduced, and a decrease in weight energy density of the power storage device can be suppressed.

(Corrosion prevention treatment layers 15a, 15b)
The corrosion prevention treatment layers 15a and 15b serve to suppress the corrosion of the metal foil layer 14 due to the electrolytic solution or hydrofluoric acid generated by the reaction between the electrolytic solution and moisture. The corrosion prevention treatment layer 15 a plays a role of increasing the adhesion between the metal foil layer 14 and the adhesive layer 13. Further, the corrosion prevention treatment layer 15 b plays a role of increasing the adhesion between the metal foil layer 14 and the sealant adhesive layer 16. The corrosion prevention treatment layer 15a and the corrosion prevention treatment layer 15b may be layers having the same configuration or different configurations. Although FIG. 1 shows the case where the corrosion prevention treatment layers are formed on both surfaces of the metal foil layer 14, the corrosion prevention treatment layers may be formed on at least one surface of the metal foil layer 14.

  Corrosion prevention treatment layers 15a and 15b are, for example, coating agents having a degreasing treatment, a hydrothermal alteration treatment, an anodizing treatment, a chemical conversion treatment, and a corrosion prevention ability for a layer that is a base material of the corrosion prevention treatment layers 15a and 15b. It can be formed by carrying out a coating-type corrosion prevention treatment in which coating is applied, or a corrosion prevention treatment combining these treatments.

  Of the above-mentioned treatments, degreasing treatment, hydrothermal modification treatment, anodizing treatment, particularly hydrothermal modification treatment and anodizing treatment are performed by dissolving the surface of the metal foil (aluminum foil) with a treating agent and having excellent corrosion resistance. This is a treatment for forming an aluminum compound (boehmite, anodized). For this reason, such a treatment may be included in the definition of chemical conversion treatment in order to obtain a structure in which a co-continuous structure is formed from the metal foil layer 14 to the corrosion prevention treatment layers 15a and 15b.

  Degreasing treatment includes acid degreasing and alkali degreasing. Examples of the acid degreasing include a method using acid degreasing obtained by mixing inorganic acids such as sulfuric acid, nitric acid, hydrochloric acid, and hydrofluoric acid as described above alone or by mixing them. Further, as acid degreasing, an acid degreasing agent in which a fluorine-containing compound such as monosodium ammonium difluoride is dissolved with the above-described inorganic acid is used, so that not only the degreasing effect of the metal foil layer 14 but also a passive metal fluoride is obtained. This is effective in terms of resistance to hydrofluoric acid. Examples of the alkaline degreasing include a method using sodium hydroxide and the like.

  As the hydrothermal modification treatment, for example, a boehmite treatment obtained by immersing the metal foil layer 14 in boiling water to which triethanolamine is added can be used. As the anodizing treatment, for example, an alumite treatment can be used. In addition, as the chemical conversion treatment, for example, chromate treatment, zirconium treatment, titanium treatment, vanadium treatment, molybdenum treatment, calcium phosphate treatment, strontium hydroxide treatment, cerium treatment, ruthenium treatment, or a combination of two or more of these is used. be able to. These hydrothermal modification treatment, anodizing treatment, and chemical conversion treatment are preferably performed in advance with the above-described degreasing treatment.

  Note that the chemical conversion treatment is not limited to a wet method, and for example, a treatment agent used in these treatments may be mixed with a resin component and applied. Moreover, as said corrosion prevention process, while the effect is maximized, the application | coating type chromate process is preferable from a viewpoint of a waste liquid process.

  The coating agent used in the coating type corrosion prevention treatment for coating the coating agent having the corrosion prevention performance contains at least one selected from the group consisting of rare earth oxide sols, anionic polymers, and cationic polymers. A coating agent is mentioned. In particular, a method using a coating agent containing a rare earth element oxide sol is preferable.

  The method using the coating agent containing the rare earth element oxide sol is a pure coating type corrosion prevention treatment. By using this method, a corrosion prevention effect is imparted to the metal foil layer 14 even by a general coating method. It is possible. Moreover, the layer formed using the rare earth element oxide sol has a corrosion prevention effect (inhibitor effect) of the metal foil layer 14 and is also a material suitable from the environmental aspect.

  In the rare earth element oxide sol, rare earth element oxide fine particles (for example, particles having an average particle diameter of 100 nm or less) are dispersed in a liquid dispersion medium. Examples of rare earth element oxides include cerium oxide, yttrium oxide, neodymium oxide, and lanthanum oxide. Of these, cerium oxide is preferable. Thereby, the adhesiveness between the metal foil layers 14 can be further improved. As the liquid dispersion medium of the rare earth element oxide sol, various solvents such as water, alcohol solvents, hydrocarbon solvents, ketone solvents, ester solvents, ether solvents and the like can be used. Of these, water is preferred. The rare earth element oxides contained in the corrosion prevention treatment layers 15a and 15b can be used singly or in combination of two or more.

  In order to stabilize the dispersion of rare earth element oxide particles, rare earth element oxide sols are used as dispersion stabilizers, such as inorganic acids such as nitric acid, hydrochloric acid and phosphoric acid, and organic substances such as acetic acid, malic acid, ascorbic acid and lactic acid. It is preferable to contain acids, salts thereof and the like. Of these dispersion stabilizers, it is particularly preferable to use phosphoric acid or phosphate. As a result, not only the dispersion stabilization of rare earth element oxide particles, but also the improvement of adhesion between the metal foil layer 14 and the use of hydrofluoric acid in the use of a lithium ion battery exterior material, utilizing the chelating ability of phosphoric acid. Effects such as imparting resistance to the electrolyte by capturing metal ions eluted by the influence (passivation formation) and improving the cohesive strength of the rare earth element oxide layer by easily causing dehydration condensation of phosphoric acid even at low temperatures can be expected. Examples of phosphoric acid or phosphate used as a dispersion stabilizer include orthophosphoric acid, pyrophosphoric acid, metaphosphoric acid, alkali metal salts and ammonium salts thereof. Among these, condensed phosphoric acid such as trimetaphosphoric acid, tetrametaphosphoric acid, hexametaphosphoric acid, and ultrametaphosphoric acid, or alkali metal salts and ammonium salts thereof are preferable for the functional expression as a lithium ion battery exterior material. In particular, considering the dry film-forming properties (drying capacity, heat quantity) when forming a layer containing rare earth oxides by various coating methods using a coating composition containing rare earth element oxide sol, the reactivity at low temperature In view of excellent dehydration condensation properties at low temperatures, sodium salts are preferred. As the phosphate, a water-soluble salt is preferable. The phosphoric acid or phosphate contained in the corrosion prevention treatment layers 15a and 15b can be used alone or in combination of two or more.

  The blending amount of phosphoric acid or a salt thereof in the rare earth element oxide sol is preferably 1 part by mass or more and more preferably 5 parts by mass or more with respect to 100 parts by mass of the rare earth element oxide. When the amount is 1 part by mass or more, the sol is stabilized well and the function as an exterior material for a lithium ion battery is easily satisfied. The upper limit of the phosphoric acid or salt thereof added to 100 parts by mass of the rare earth element oxide may be in a range not accompanied by a decrease in the function of the rare earth element oxide sol, and is 100 parts by mass or less with respect to 100 parts by mass of the rare earth element oxide. Preferably, 50 parts by mass or less is more preferable, and 20 parts by mass or less is more preferable.

  However, since the layer formed from the rare earth element oxide sol described above is an aggregate of inorganic particles, the cohesive force of the layer itself is low even after the drying curing process. Therefore, in order to supplement the cohesive force of this layer, it is preferable to make a composite with an anionic polymer.

  As an anionic polymer, the polymer which has a carboxy group is mentioned, For example, the copolymer which copolymerized poly (meth) acrylic acid (or its salt) or poly (meth) acrylic acid as a main component is mentioned. The copolymer component of the copolymer includes an alkyl (meth) acrylate monomer (the alkyl group includes a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, t-butyl group, 2-ethylhexyl group, cyclohexyl group, etc.); (meth) acrylamide, N-alkyl (meth) acrylamide, N, N-dialkyl (meth) acrylamide (alkyl groups include methyl, ethyl, n-propyl group, i-propyl group, n-butyl group, i-butyl group, t-butyl group, 2-ethylhexyl group, cyclohexyl group, etc.), N-alkoxy (meth) acrylamide, N, N- Dialkoxy (meth) acrylamide (as alkoxy groups, methoxy group, ethoxy group, butoxy group, isobutoxy group, etc.), N-methyl Amide group-containing monomers such as diol (meth) acrylamide and N-phenyl (meth) acrylamide; Hydroxyl-containing monomers such as 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate; Glycidyl (meth) acrylate, Glycidyl group-containing monomers such as allyl glycidyl ether; Silane-containing monomers such as (meth) acryloxypropyltrimethoxysilane and (meth) acryloxypropyltriethoxysilane; Isocyanate groups such as (meth) acryloxypropyl isocyanate And monomers. Also, styrene, α-methylstyrene, vinyl methyl ether, vinyl ethyl ether, maleic acid, alkyl maleic acid monoester, fumaric acid, alkyl fumaric acid monoester, itaconic acid, alkyl itaconic acid monoester, (meth) acrylonitrile, chloride Examples include vinylidene, ethylene, propylene, vinyl chloride, vinyl acetate, and butadiene.

  An anionic polymer plays the role which improves the stability of the corrosion prevention process layers 15a and 15b (oxide layer) obtained using rare earth element oxide sol. This is due to the effect of protecting the hard and brittle oxide layer with an acrylic resin component and the effect of capturing ion contamination (especially sodium ions) derived from phosphate contained in the rare earth oxide sol (cation catcher). Achieved. That is, when the corrosion prevention treatment layers 15a and 15b obtained using the rare earth element oxide sol contain alkali metal ions or alkaline earth metal ions such as sodium in particular, starting from the place containing the ions. The corrosion prevention treatment layers 15a and 15b are liable to deteriorate. Therefore, the resistance of the corrosion prevention treatment layers 15a and 15b is improved by fixing sodium ions and the like contained in the rare earth oxide sol by the anionic polymer.

  Corrosion prevention treatment layers 15a and 15b combined with an anionic polymer and a rare earth element oxide sol have the same corrosion prevention performance as the corrosion prevention treatment layers 15a and 15b formed by subjecting the metal foil layer 14 to chromate treatment. The anionic polymer preferably has a structure in which a polyanionic polymer that is essentially water-soluble is crosslinked. Examples of the crosslinking agent used for forming the structure include compounds having an isocyanate group, a glycidyl group, a carboxy group, and an oxazoline group. Furthermore, it is also possible to introduce a crosslinking site having a siloxane bond using a silane coupling agent.

  Examples of the compound having an isocyanate group include diisocyanates such as tolylene diisocyanate, xylylene diisocyanate or hydrogenated products thereof, hexamethylene diisocyanate, 4,4′-diphenylmethane diisocyanate or hydrogenated products thereof, and isophorone diisocyanate compounds. Or adducts obtained by reacting these isocyanates with polyhydric alcohols such as trimethylolpropane, bures obtained by reacting with water, or isocyanurates which are trimers. Isocyanates; or block polyisocyanates obtained by blocking these polyisocyanates with alcohols, lactams, oximes, and the like.

  Examples of the compound having a glycidyl group include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, 1,4-butanediol, 1,6-hexanediol, Epoxy hydrin was reacted with polyhydric alcohols such as epoxy compounds, glycerin, polyglycerin, trimethylolpropane, pentaerythritol, sorbyl, etc., which were reacted with glycols such as neopentyl glycol and epiquinol hydrin. Examples thereof include an epoxy compound, an epoxy compound obtained by reacting a dicarboxylic acid such as phthalic acid, terephthalic acid, oxalic acid, and adipic acid with epichlorohydrin.

  Examples of the compound having a carboxy group include various aliphatic or aromatic dicarboxylic acids, and it is also possible to use poly (meth) acrylic acid and alkali (earth) metal salts of poly (meth) acrylic acid. is there.

  As the compound having an oxazoline group, for example, a low molecular compound having two or more oxazoline units, or a polymerizable monomer such as isopropenyl oxazoline, (meth) acrylic acid, (meth) acrylic acid alkyl ester And a compound obtained by copolymerizing an acrylic monomer such as hydroxyalkyl (meth) acrylate.

  As the silane coupling agent, γ-glycidoxypropyl-trimethoxysilane, γ-glycidoxypropyltriethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-chloropropylmethoxysilane, Examples include vinyltrichlorosilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β (aminoethyl) -γ-aminopropyltrimethoxysilane, and γ-isocyanatopropyltriethoxysilane, particularly anions. In view of the reactivity with the functional polymer, epoxy silane, amino silane, and isocyanate silane are preferable.

  1-50 mass parts is preferable with respect to 100 mass parts of anionic polymers, and, as for the compounding quantity of a crosslinking agent, 10-20 mass parts is more preferable. When the ratio of the crosslinking agent is 1 part by mass or more with respect to 100 parts by mass of the anionic polymer, a crosslinked structure is easily formed. When the ratio of the crosslinking agent is 50 parts by mass or less with respect to 100 parts by mass of the anionic polymer, the pot life of the coating liquid is improved.

  The method for crosslinking the anionic polymer is not limited to the above-mentioned crosslinking agent, and may be a method for forming ionic crosslinking using a titanium or zirconium compound. Moreover, you may apply the coating composition which forms the corrosion prevention process layer 15a to these materials.

  In the corrosion prevention treatment layers 15a and 15b described above, the corrosion prevention treatment layers 15a and 15b by chemical conversion treatment represented by chromate treatment are formed with an inclined structure with the metal foil layer 14, and in particular, hydrofluoric acid, hydrochloric acid, nitric acid. Then, the metal foil layer 14 is treated using a chemical conversion treatment agent containing sulfuric acid or a salt thereof, and then a chemical conversion treatment layer is formed on the metal foil layer 14 by the action of a chromium-based or non-chromium-based compound. However, since the said chemical conversion treatment uses the acid for a chemical conversion treatment agent, it is accompanied by deterioration of a working environment and corrosion of a coating apparatus.

  On the other hand, unlike the chemical conversion treatment represented by the chromate treatment, the coating-type corrosion prevention treatment layers 15a and 15b described above do not require an inclined structure to be formed on the metal foil layer. Therefore, the properties of the coating agent are not subject to restrictions such as acidity, alkalinity, and neutrality, and a good working environment can be realized. In addition, the chromate treatment using a chromium compound is preferably the coating-type corrosion prevention treatment layers 15a and 15b from the viewpoint that an alternative is required for environmental hygiene.

  The corrosion prevention treatment layers 15a and 15b may have a laminated structure in which a cationic polymer is further laminated as necessary. Examples of the cationic polymer include polyethyleneimine, an ionic polymer complex composed of polyethyleneimine and a polymer having a carboxylic acid, a primary amine-grafted acrylic resin in which a primary amine is graphed on an acrylic main skeleton, polyallylamine, or derivatives thereof. And aminophenol resins.

  Examples of the “polymer having a carboxylic acid” forming an ionic polymer complex include polycarboxylic acid (salt), a copolymer in which a comonomer is introduced into polycarboxylic acid (salt), a polysaccharide having a carboxy group, and the like. It is done. Examples of the polycarboxylic acid (salt) include polyacrylic acid or an ionic salt thereof. Examples of the polysaccharide having a carboxy group include carboxymethyl cellulose or an ionic salt thereof. Examples of the ionic salt include alkali metal salts and alkaline earth metal salts.

  The primary amine graph acrylic resin is a resin obtained by graphing a primary amine on an acrylic main skeleton. Examples of the acrylic main skeleton include various monomers used in the above-described acrylic polyol, such as poly (meth) acrylic acid. Examples of the primary amine graphed on the acrylic main skeleton include ethyleneimine.

  As polyallylamine or derivatives thereof, homopolymers or copolymers of allylamine, allylamine amide sulfate, diallylamine, dimethylallylamine, etc. can be used. Furthermore, these amines can be free amines or acetic acid or hydrochloric acid. Stabilized products can also be used. Further, maleic acid, sulfur dioxide or the like can be used as a copolymer component. Furthermore, it is possible to use a type in which a primary amine is partially methoxylated to impart thermal crosslinkability. These cationic polymers may be used alone or in combination of two or more. Among the above, the cationic polymer is preferably at least one selected from the group consisting of polyallylamine and derivatives thereof.

  The cationic polymer is preferably used in combination with a crosslinking agent having a functional group capable of reacting with an amine / imine such as a carboxy group or a glycidyl group. As the crosslinking agent used in combination with the cationic polymer, a polymer having a carboxylic acid that forms an ionic polymer complex with polyethyleneimine can also be used. For example, a polycarboxylic acid (salt) such as polyacrylic acid or an ionic salt thereof, or the like And a copolymer having a carboxy group such as carboxymethylcellulose or an ionic salt thereof.

  In the present embodiment, the cationic polymer is also described as one component constituting the corrosion prevention treatment layers 15a and 15b. The reason for this is that, as a result of intensive studies using various compounds to provide the electrolyte resistance and hydrofluoric acid resistance required for the exterior materials for lithium ion batteries, the cationic polymer itself also has electrolyte resistance and anti-fluorine resistance. This is because the compound was found to be capable of imparting acidity. This factor is presumed to be because the metal foil layer 14 is prevented from being damaged by capturing fluorine ions with a cationic group (anion catcher). The cationic polymer is also very preferable in terms of improving the adhesion between the corrosion prevention treatment layer 15 b and the sealant adhesive layer 16. Further, since the cationic polymer is water-soluble like the anionic polymer described above, the water resistance can be improved by forming a crosslinked structure using the above-mentioned crosslinking agent. Thus, since a crosslinked structure can be formed even if a cationic polymer is used, when a rare earth oxide sol is used for forming the corrosion prevention treatment layers 15a and 15b, an anionic polymer is used as the protective layer. Instead, a cationic polymer may be used.

  From the above contents, examples of combinations of the above-described coating type corrosion prevention treatments are as follows: (1) only rare earth oxide sol, (2) only anionic polymer, (3) only cationic polymer, (4) rare earth oxide Sol + anionic polymer (laminated composite), (5) rare earth oxide sol + cationic polymer (laminated composite), (6) (rare earth oxide sol + anionic polymer: laminated composite) / cationic polymer ( (Multilayered), (7) (rare earth oxide sol + cationic polymer: laminated composite) / anionic polymer (multilayered), and the like. Among these, (1) and (4) to (7) are preferable, and (4) to (7) are more preferable. In the case of the corrosion prevention treatment layer 15a, (6) is particularly preferable because the corrosion prevention effect and the anchor effect (adhesion improvement effect) can be further realized. In the case of the corrosion prevention treatment layer 15b, (6) and (7) are particularly preferable because the resistance to the electrolyte solution on the sealant layer 17 side can be more easily maintained. However, the present embodiment is not limited to the above combination. For example, as an example of the selection of the corrosion prevention treatment, the cationic polymer is a very preferable material in that it has a good adhesiveness with the modified polyolefin resin mentioned in the description of the sealant adhesive layer 16 described later. In the case where the layer 16 is composed of a modified polyolefin resin, it is possible to design such that a cationic polymer is provided on the surface in contact with the sealant adhesive layer 16 (for example, configurations (5) and (6)).

  However, the corrosion prevention treatment layers 15a and 15b are not limited to the layers described above. For example, it may be formed using an agent in which phosphoric acid and a chromium compound are blended in a resin binder (aminophenol resin or the like), such as a coating chromate that is a known technique. If this processing agent is used, it becomes possible to form a layer having both a corrosion prevention function and adhesion. Moreover, in order to improve adhesiveness with respect to the chemical conversion treatment layer (a layer formed by degreasing treatment, hydrothermal modification treatment, anodizing treatment, chemical conversion treatment, or a combination of these treatments), the cationic property described above is used. It is also possible to perform a complex treatment using a polymer and / or an anionic polymer, or to laminate a cationic polymer and / or an anionic polymer as a multilayer structure for a combination of these treatments. In addition, although it is necessary to consider the stability of the coating solution, it is possible to prevent corrosion by using a coating agent obtained by previously making the rare earth oxide sol and the cationic polymer or anionic polymer into one solution. And a layer having both adhesion and adhesion.

Corrosion treatment layer 15a, the mass per unit area of 15b is preferably in a range of 0.005~0.200g / ^{m 2,} the range of 0.010~0.100g / ^{m 2} is more preferable. If it is 0.005 g / m ² or more, the metal foil layer 14 is easily imparted with a corrosion prevention function. Even if the mass per unit area exceeds 0.200 g / m ² , the corrosion prevention function is saturated and does not change much. On the other hand, when the rare earth oxide sol is used, if the coating film is thick, curing due to heat at the time of drying becomes insufficient, and there is a possibility that the cohesive force is lowered. In addition, although it described with the mass per unit area in the said content, if specific gravity is known, it is also possible to convert thickness from there.

  The thickness of the corrosion prevention treatment layers 15a and 15b is, for example, preferably 10 nm to 5 μm, and more preferably 20 to 500 nm, from the viewpoint of the corrosion prevention function and the function as an anchor.

(Sealant adhesive layer 16)
The sealant adhesive layer 16 is a layer that bonds the metal foil layer 14 on which the corrosion prevention treatment layer 15 b is formed and the sealant layer 17. The exterior material 10 is roughly divided into a thermal laminate configuration and a dry laminate configuration depending on the adhesive component that forms the sealant adhesive layer 16.

  The adhesive component forming the sealant adhesive layer 16 in the heat laminate configuration is preferably an acid-modified polyolefin resin obtained by graft-modifying a polyolefin resin with an acid. Since the acid-modified polyolefin-based resin has a polar group introduced in a part of the non-polar polyolefin-based resin, the acid-modified polyolefin-based resin has a polarity with the sealant layer 17 formed of a non-polar polyolefin-based resin film or the like. In many cases, it can be firmly adhered to both of the corrosion prevention treatment layers 15b. In addition, the use of the acid-modified polyolefin resin improves the resistance of the exterior material 10 to the contents such as the electrolyte, and even if hydrofluoric acid is generated inside the battery, the adhesive strength is reduced due to deterioration of the sealant adhesive layer 16. It is easy to prevent.

  Examples of the polyolefin resin of the acid-modified polyolefin resin include low density, medium density and high density polyethylene; ethylene-α olefin copolymer; polypropylene; and propylene-α olefin copolymer. The polyolefin resin in the case of a copolymer may be a block copolymer or a random copolymer. Further, as the polyolefin resin, a copolymer obtained by copolymerizing a polar molecule such as acrylic acid or methacrylic acid with the above-described one, or a polymer such as a crosslinked polyolefin can be used. Examples of the acid that modifies the polyolefin resin include carboxylic acid, epoxy compound, and acid anhydride, and maleic anhydride is preferable. The acid-modified polyolefin resin used for the sealant adhesive layer 16 may be one type or two or more types.

  The heat-laminated sealant adhesive layer 16 can be formed by extruding the adhesive component with an extrusion device. The thickness of the heat-bonded sealant adhesive layer 16 is preferably 2 to 50 μm.

  Examples of the adhesive component for forming the sealant adhesive layer 16 having a dry laminate structure include the same adhesives as those mentioned for the adhesive layer 13. In this case, in order to suppress swelling due to the electrolyte and hydrolysis due to hydrofluoric acid, the composition of the adhesive may be designed so that it is a main component of a skeleton that is difficult to hydrolyze and that can improve the crosslinking density. preferable.

  In order to improve the crosslinking density, for example, dimer fatty acid, dimer fatty acid ester or hydrogenated product, dimer fatty acid reduced glycol, dimer fatty acid ester or hydrogenated reduced glycol may be added to the adhesive. The dimer fatty acid is an acid obtained by dimerizing various unsaturated fatty acids, and examples of the structure include acyclic, monocyclic, polycyclic and aromatic ring types.

  The fatty acid that is a starting material of the dimer fatty acid is not particularly limited. Moreover, you may introduce | transduce such a dibasic acid used with a normal polyester polyol by using such a dimer fatty acid as an essential component. As a hardening | curing agent with respect to the main ingredient which comprises the sealant contact bonding layer 16, it is possible to use the isocyanate compound which can be used also as a chain extender of a polyester polyol, for example. As a result, the crosslinking density of the adhesive coating film increases, leading to improvements in solubility and swelling, and an increase in the urethane group concentration can also be expected to improve substrate adhesion.

  Since the sealant adhesive layer 16 having a dry laminate structure has a highly hydrolyzable bonding portion such as an ester group and a urethane group, a heat laminate structure is used as the sealant adhesive layer 16 for applications requiring higher reliability. It is preferable to use the adhesive component. For example, the sealant adhesive layer 16 is formed by blending the above-mentioned various curing agents in a coating solution obtained by dissolving or dispersing an acid-modified polyolefin resin in a solvent such as toluene or methylcyclohexane (MCH), and applying and drying. To do.

  When the sealant adhesive layer 16 is formed by extrusion molding, the adhesive resin is easily oriented in the MD direction (extrusion direction) due to stress generated during the extrusion molding. In this case, an elastomer may be blended in the sealant adhesive layer 16 in order to relax the anisotropy of the sealant adhesive layer 16. As an elastomer mix | blended with the sealant contact bonding layer 16, an olefin-type elastomer, a styrene-type elastomer, etc. can be used, for example.

  The average particle size of the elastomer is preferably a particle size capable of improving the compatibility between the elastomer and the adhesive resin and improving the effect of relaxing the anisotropy of the sealant adhesive layer 16. Specifically, the average particle diameter of the elastomer is preferably 200 nm or less, for example.

  The average particle size of the elastomer can be obtained, for example, by taking a photograph of an enlarged cross section of the elastomer composition with an electron microscope and then measuring the average particle size of the dispersed crosslinked rubber component by image analysis. . The said elastomer may be used individually by 1 type, and may be used in combination of 2 or more type.

  When blending an elastomer in the sealant adhesive layer 16, the blending amount of the elastomer added to the sealant adhesive layer 16 (100 mass%) is, for example, preferably 1 to 25 mass%, more preferably 10 to 20 mass%. By setting the blending amount of the elastomer to 1% by mass or more, the compatibility with the adhesive resin is improved, and the effect of relaxing the anisotropy of the sealant adhesive layer 16 tends to be improved. Moreover, there exists a tendency for the effect which suppresses that the sealant contact bonding layer 16 swells with electrolyte solution by making the compounding quantity of an elastomer into 25 mass% or less.

  As the sealant adhesive layer 16, for example, a dispersion type adhesive resin liquid in which an adhesive resin is dispersed in an organic solvent may be used.

  In the case of a heat laminate configuration, the thickness of the sealant adhesive layer 16 is preferably 2 to 50 μm, and more preferably 20 to 40 μm. When the thickness of the sealant adhesive layer 16 is 2 μm or more, sufficient adhesive strength between the metal foil layer 14 and the sealant layer 17 can be easily obtained. It is possible to easily reduce the amount of moisture entering. The thickness of the sealant adhesive layer 16 is preferably 1 to 5 μm in the case of a dry laminate configuration. When the thickness of the sealant adhesive layer 16 is 1 μm or more, sufficient adhesion strength between the metal foil layer 14 and the sealant layer 17 is easily obtained, and when the thickness is 5 μm or less, the sealant adhesive layer 16 is not cracked. Can be suppressed.

(Sealant layer 17)
The sealant layer 17 is a layer that imparts a sealing property to the exterior material 10 by heat sealing, and is a layer that is disposed on the inner side and assembled by heat fusion when the power storage device is assembled. Examples of the sealant layer 17 include a polyolefin resin or a resin film made of an acid-modified polyolefin resin obtained by graft-modifying an acid such as maleic anhydride to a polyolefin resin. Among these, a polyolefin-based resin that improves the barrier property of water vapor and can form the power storage device without being excessively crushed by heat sealing is preferable, and polypropylene is particularly preferable.

  Examples of the polyolefin-based resin include low density, medium density and high density polyethylene; ethylene-α olefin copolymer; polypropylene; and propylene-α olefin copolymer. The polyolefin resin in the case of a copolymer may be a block copolymer or a random copolymer. These polyolefin resin may be used individually by 1 type, and may use 2 or more types together.

  In addition, each of the above-mentioned types of polypropylene, that is, random polypropylene, homopolypropylene, and block polypropylene includes low crystalline ethylene-butene copolymer, low crystalline propylene-butene copolymer, ethylene, butene, and propylene 3 A terpolymer made of a component copolymer, silica, zeolite, an antiblocking agent (AB agent) such as acrylic resin beads, a fatty acid amide slip agent, or the like may be added.

  Examples of the acid-modified polyolefin-based resin include those similar to those exemplified in the sealant adhesive layer 16.

  The sealant layer 17 may be a single layer film or a multilayer film, and may be selected according to a required function. For example, in terms of imparting moisture resistance, a multilayer film in which a resin such as an ethylene-cyclic olefin copolymer and polymethylpentene is interposed can be used.

  The sealant layer 17 may contain various additives such as a flame retardant, a slip agent, an antiblocking agent, an antioxidant, a light stabilizer, and a tackifier.

  When a heat-weldable film formed by extrusion molding is used as the sealant layer 17, there is an orientation tendency in the extrusion direction of the heat-weldable film. For this reason, an elastomer may be blended in the heat-weldable film from the viewpoint of relaxing the anisotropy of the sealant layer 17 due to orientation. Thereby, it can suppress that the sealant layer 17 whitens when cold-molding the exterior | covering material 10 for electrical storage devices and forming a recessed part.

  As the elastomer constituting the sealant layer 17, for example, the same material as the material exemplified as the elastomer constituting the sealant adhesive layer 16 can be used. When the sealant layer 17 has a multilayer film structure, at least one of the plurality of layers constituting the multilayer film structure may include an elastomer. For example, when the sealant layer 17 has a three-layer laminated structure composed of laminated random polypropylene layer / block polypropylene layer / random polypropylene layer, the elastomer may be blended only in the block polypropylene layer or only in the random polypropylene layer. You may mix | blend and you may mix | blend with both a random polypropylene layer and a block polypropylene layer.

  Further, a lubricant may be included in order to impart slipperiness to the sealant layer 17. As described above, when the sealant layer 17 contains the lubricant, when forming the recess in the power storage device exterior material 10 by cold forming, the side or corner of the recess having a high stretch ratio in the power storage device exterior material 10 It becomes possible to suppress that the part which becomes becomes unnecessarily extended | stretched. Thereby, it can suppress that between the metal foil layer 14 and the sealant contact bonding layer 16 peels, or the fracture | rupture and whitening by a crack arise in the sealant layer 17 and the sealant contact bonding layer 16.

  When the sealant layer 17 contains a lubricant, the content of the lubricant in the sealant layer 17 (100% by mass) is preferably 0.001 to 0.5% by mass. There exists a tendency which can suppress more that the sealant layer 17 whitens at the time of cold molding as content of a lubricant is 0.001 mass% or more. Moreover, there exists a tendency which can suppress the fall of the adhesive strength between the surfaces of the other layer which contacts the surface of the sealant layer 17 as content of a lubricant is 0.5 mass% or less.

  The thickness of the sealant layer 17 is preferably 10 to 100 μm, and more preferably 20 to 60 μm. When the thickness of the sealant layer 17 is 10 μm or more, sufficient heat seal strength can be obtained, and when it is 100 μm or less, the amount of water vapor entering from the edge of the exterior material can be reduced.

[Method of manufacturing exterior material]
Next, the manufacturing method of the exterior material 10 is demonstrated. In addition, the manufacturing method of the exterior material 10 is not limited to the following method.

As a manufacturing method of the exterior material 10, the method which has following process S11-S14 is mentioned, for example.
Step S11: A step of forming the corrosion prevention treatment layer 15a on one surface of the metal foil layer 14 and the corrosion prevention treatment layer 15b on the other surface of the metal foil layer 14.
Process S12: The process of forming the easily bonding process layer 12 on one surface of the base material layer 11, and obtaining a laminated body. Step S13: A step of bonding the surface of the corrosion prevention treatment layer 15a opposite to the metal foil layer 14 and the surface of the laminate on the side of the easy adhesion treatment layer 12 via the adhesive layer 13.
Step S14: A step of forming a sealant layer 17 via a sealant adhesive layer 16 on the surface of the corrosion prevention treatment layer 15b opposite to the metal foil layer 14.

(Process S11)
In step S11, the corrosion prevention treatment layer 15a is formed on one surface of the metal foil layer 14, and the corrosion prevention treatment layer 15b is formed on the other surface of the metal foil layer 14. The corrosion prevention treatment layers 15a and 15b may be formed separately, or both may be formed at once. Specifically, for example, a corrosion prevention treatment agent (base material of the corrosion prevention treatment layer) is applied to both surfaces of the metal foil layer 14, and thereafter, drying, curing, and baking are sequentially performed. 15a and 15b are formed at once. In addition, after applying a corrosion prevention treatment agent to one surface of the metal foil layer 14, drying, curing, and baking are sequentially performed to form the corrosion prevention treatment layer 15 a, the same is applied to the other surface of the metal foil layer 14. The corrosion prevention treatment layer 15b may be formed. The order in which the corrosion prevention treatment layers 15a and 15b are formed is not particularly limited. Further, different corrosion prevention treatment agents may be used for the corrosion prevention treatment layer 15a and the corrosion prevention treatment layer 15b, or the same one may be used. As said corrosion prevention processing agent, the corrosion prevention processing agent for coating type chromate processing etc. can be used, for example. The coating method of the corrosion inhibitor is not particularly limited. For example, gravure coating method, gravure reverse coating method, roll coating method, reverse roll coating method, die coating method, bar coating method, kiss coating method, comma coating method, etc. Can be used. In addition, as the metal foil layer 14, an untreated metal foil layer may be used, or a metal foil layer subjected to degreasing treatment by wet type degreasing treatment or dry type degreasing treatment may be used.

(Process S12)
In step S <b> 12, the easy adhesion treatment layer 12 is formed on one surface of the base material layer 11. Here, an in-line coating method will be described as an example of a method for forming the easy adhesion treatment layer 12. First, an aqueous coating solution containing a dispersion in which the above-described resin that is the main component of the easy adhesion treatment layer 12 is dispersed with a dispersant is prepared. Subsequently, the said aqueous coating liquid is apply | coated to one surface of the thermoplastic resin film (base material of the base material layer 11) before crystal orientation is completed. Next, the applied aqueous coating solution is dried, and then the thermoplastic resin film is stretched in at least a uniaxial direction.

  Subsequently, the laminated body in which the easily bonding process layer 12 was formed on one surface of the base material layer 11 is obtained by completing orientation of a thermoplastic resin film by heat processing. By forming the easy adhesion treatment layer 12 using such an in-line coating method, the adhesion between the base material layer 11 and the easy adhesion treatment layer 12 is improved. In addition, the formation method of the easily bonding process layer 12 is not limited to the said method, You may use what kind of method. Moreover, the timing which forms the easily bonding process layer 12 is not limited to this Embodiment.

(Process S13)
In step S13, the surface on the opposite side to the metal foil layer 14 of the corrosion prevention treatment layer 15a and the surface on the easy adhesion treatment layer 12 side of the laminate are dry-laminated using an adhesive that forms the adhesion layer 13. It is pasted together by the technique. In step S13, an aging (curing) treatment may be performed in the range of room temperature to 100 ° C. to promote adhesion. The aging time is, for example, 1 to 10 days.

(Process S14)
After step S13, the base material layer 11, the easy adhesion treatment layer 12, the adhesion layer 13, the corrosion prevention treatment layer 15a, the metal foil layer 14 and the corrosion prevention treatment layer 15b are laminated in this order on the corrosion prevention treatment layer 15b of the laminate. A sealant layer 17 is formed on the surface opposite to the metal foil layer 14 via a sealant adhesive layer 16. The sealant layer 17 may be laminated by dry lamination, sandwich lamination, or the like, or may be laminated together with the sealant adhesive layer 16 by a coextrusion method. From the viewpoint of improving adhesiveness, the sealant layer 17 is preferably laminated by, for example, sandwich lamination, or is preferably laminated by the coextrusion method together with the sealant adhesive layer 16, and more preferably by sandwich lamination.

  The exterior material 10 is obtained by the steps S11 to S14 described above. In addition, the process sequence of the manufacturing method of the cladding | exterior_material 10 is not limited to the method of implementing said process S11-S14 sequentially. For example, the order of steps to be performed may be changed as appropriate, such as step S11 after step S12.

[Power storage device]
Next, a power storage device including the exterior material 10 as a container will be described. The power storage device includes a battery element 1 including an electrode, a lead 2 extending from the electrode, and a container that sandwiches the lead 2 and accommodates the battery element 1. The sealant layer 17 is formed on the inner side. The container may be obtained by stacking two exterior materials with the sealant layers 17 facing each other, and heat-sealing the peripheral edge of the overlaid exterior material 10, or by folding back one exterior material. It may be obtained by overlapping and similarly heat-sealing the peripheral portion of the exterior material 10. The power storage device may include the exterior material 20 as a container. Examples of the power storage device include secondary batteries such as lithium ion batteries, nickel metal hydride batteries, and lead storage batteries, and electrochemical capacitors such as electric double layer capacitors.

  The lead 2 is sandwiched and sealed by an exterior material 10 that forms a container with the sealant layer 17 inside. The lead 2 may be clamped by the exterior material 10 via a tab sealant.

[Method for Manufacturing Power Storage Device]
Next, a method for manufacturing a power storage device using the above-described exterior material 10 will be described. Here, a case where the secondary battery 40 is manufactured using the embossed type exterior material 30 will be described as an example. FIG. 2 is a view showing the embossed type exterior member 30. FIGS. 3A to 3D are perspective views showing a manufacturing process of a one-side molded battery using the exterior material 10. The secondary battery 40 is a double-sided molded battery that is manufactured by bonding two exterior materials such as the embossed type exterior material 30 and bonding the exterior materials together while adjusting the alignment. Also good. Further, the embossed type exterior material 30 may be formed using the exterior material 20.

The secondary battery 40 that is a one-side molded battery can be manufactured, for example, by the following steps S21 to S25.
Step S21: A step of preparing the outer packaging material 10, the battery element 1 including the electrodes, and the leads 2 extending from the electrodes.
Step S22: A step of forming a recess 32 for disposing the battery element 1 on one side of the exterior material 10 (see FIGS. 3A and 3B).
Step S23: The battery element 1 is arranged in the molding processing area (recessed portion 32) of the embossed-type exterior member 30, and the embossed-type exterior member 30 is folded and overlapped so that the lid portion 34 covers the recessed portion 32, and extends from the battery element 1. A step of pressurizing and heat-bonding one side of the embossed type exterior member 30 so as to sandwich the lead 2 to be held (see FIGS. 3B and 3C).
Step S24: Leave one side other than the side sandwiching the lead 2 and pressurize and melt the other side, then inject the electrolyte from the remaining side and pressurize and heat-bond the remaining side in a vacuum state Step (see FIG. 3C).
Step S25: A step of cutting the end portion of the pressurization heat fusion other than the side sandwiching the lead 2 and bending it to the side of the molding area (recess 32) (see FIG. 3D).

(Process S21)
In step S21, the exterior material 10, the battery element 1 including the electrodes, and the leads 2 extending from the electrodes are prepared. The exterior material 10 is prepared based on the above-described embodiment. There is no restriction | limiting in particular as the battery element 1 and the lead 2, The well-known battery element 1 and the lead 2 can be used.

(Step S22)
In step S22, a recess 32 for disposing the battery element 1 on the sealant layer 17 side of the exterior material 10 is formed. The planar shape of the recess 32 is a shape that matches the shape of the battery element 1, for example, a rectangular shape in plan view. The recess 32 is formed, for example, by pressing a pressing member having a rectangular pressure surface against a part of the exterior material 10 in the thickness direction. Further, the pressing position, that is, the recess 32 is formed at a position deviated from the center of the exterior material 10 cut into a rectangle toward one end in the longitudinal direction of the exterior material 10. Thereby, the other end part side which does not form the recessed part 32 after a shaping | molding process can be turned back, and it can be set as a cover (lid part 34).

  More specifically, a method of forming the recess 32 includes a molding process using a mold (deep drawing molding). As a molding method, a female mold and a male mold disposed so as to have a gap larger than the thickness of the exterior material 10 are used, and the male mold is pushed into the female mold together with the exterior material 10. Is mentioned. By adjusting the pushing amount of the male mold, the depth (deep drawing amount) of the recess 32 can be adjusted to a desired amount. The embossed type exterior material 30 is obtained by forming the recess 32 in the exterior material 10. The embossed type exterior member 30 has a shape as shown in FIG. 2, for example. Here, FIG. 2 (a) is a perspective view of the embossed type exterior member 30, and FIG. 2 (b) is a longitudinal section along the line bb of the embossed type exterior member 30 shown in FIG. 2 (a). FIG.

(Step S23)
In step S <b> 23, the battery element 1 including the positive electrode, the separator, the negative electrode, and the like is disposed in the molding processing area (recess 32) of the embossed type exterior material 30. Further, the lead 2 extending from the battery element 1 and bonded to the positive electrode and the negative electrode, respectively, is drawn out from the molding area (recess 32). Thereafter, the embossed type exterior member 30 is folded back at substantially the center in the longitudinal direction, and the sealant layers 17 are stacked so as to be inside, and one side of the embossed type exterior member 30 sandwiching the lead 2 is subjected to pressure heat fusion. The The pressure heat fusion is controlled by three conditions of temperature, pressure, and time, and is appropriately set. The temperature of the pressure heat fusion is preferably equal to or higher than the temperature at which the sealant layer 17 is melted.

  Note that the thickness of the sealant layer 17 before heat sealing is preferably 40 to 80% of the thickness of the lead 2. When the thickness of the sealant layer 17 is equal to or greater than the lower limit value, the heat-sealing resin tends to sufficiently fill the end of the lead 2, and when the thickness is equal to or less than the upper limit value, the exterior material 10 of the secondary battery 40. The thickness of the end can be moderately suppressed, and the amount of moisture permeating from the end of the exterior material 10 can be reduced.

(Process S24)
In step S24, one side other than the side sandwiching the lead 2 is left and the other side is subjected to pressure heat fusion. Thereafter, an electrolytic solution is injected from the remaining side, and the remaining side is pressurized and heat-sealed in a vacuum state. The conditions for the pressure heat fusion are the same as in step S23.

(Step S25)
Edge edges of the peripheral pressure heat-sealing side other than the sides sandwiching the lead 2 are cut, and the sealant layer 17 protruding from the ends is removed. Then, the secondary battery 40 is obtained by folding the peripheral pressure heat-sealed portion toward the molding area 32 and forming the folded portion 42.

  As mentioned above, the preferred embodiment of the exterior material for the power storage device and the method for manufacturing the power storage device of the present invention has been described in detail, but the present invention is not limited to such specific embodiment, and is within the scope of the claims. Various modifications and changes can be made within the scope of the gist of the present invention described.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example, this invention is not limited to a following example.

(Preparation of base material layer)
As the base material layer 11, a polyester film having the characteristics shown in Table 1 (both having a thickness of 25 μm) was prepared. In Table 1, ΔA is a value represented by the following formula (1), and F50 ²⁰⁰ represents a stress value at 50% elongation after heat treatment at 200 ° C.
ΔA = (breaking elongation after heat treatment at 200 ° C.) − (Breaking elongation after heat treatment at 160 ° C.) (1)

The elongation at break and the stress value at 50% elongation were measured as follows. That is, the polyester film cut into A4 size is heated in an oven maintained at an arbitrary heat treatment temperature (160 ° C. or 200 ° C.) for 30 minutes, and then the four directions of the base material layer (0 ° (MD), 45 Tensile test at 23 ° C (°, 90 ° (TD), 135 °) (Test piece shape: No. 5 type dumbbell defined in JIS K7127, Chuck distance: 75 mm, Gage distance: 25 mm, Test speed: 50 mm / min). And the fracture | rupture elongation in this embodiment and the stress value at the time of 50% elongation were computed by taking the average of the measurement result with respect to 4 directions. However, the elongation at break is a value calculated as follows.
Elongation at break (%) = {(Distance between gauge points at break−Distance between gauge points before measurement) / Distance between gauge points before measurement} × 100

(Preparation of coating agent for easy adhesion treatment layer formation)
As a coating agent for forming an easy adhesion treatment layer, a coating agent having the following composition was prepared.
Coating agent: water-soluble polyester “Aronmelt PES-1000” manufactured by Toagosei Co., Ltd., self-emulsifying type polyisocyanate “Aquanate 100” manufactured by Nihon Polyurethane Industry Co., Ltd., and spherical silica manufactured by Nippon Shokubai Chemical Co., Ltd. Fine particles “Seahoster KE-P30” (average particle size 0.3 μm) were added at a blending ratio (mass ratio) of 95/5 / 0.5, and diluted with water.

Example 1
In Example 1, the power storage device exterior material 10 was produced by the following method. First, a 40 μm-thick soft aluminum foil 8079 material (manufactured by Toyo Aluminum Co., Ltd.) was prepared as the metal foil layer 14. Subsequently, sodium polyphosphate-stabilized cerium oxide sol (corrosion prevention treatment agent) was applied to both surfaces of the metal foil layer 14 by gravure coating using distilled water as a solvent and adjusting the solid content concentration to 10% by mass. At this time, phosphoric acid was 10 mass parts with respect to 100 mass parts of cerium oxide.

  Next, after drying the applied sodium polyphosphate-stabilized cerium oxide sol, a baking treatment is sequentially performed to form a corrosion prevention treatment layer 15a on one surface of the metal foil layer 14 and corrosion prevention on the other surface. A treatment layer 15b was formed. At this time, the baking conditions were a temperature of 150 ° C. and a processing time of 30 seconds.

  Subsequently, as the base material layer 11, the polyester film A-1 was used and the single side | surface of the base material layer 11 was corona-treated.

  Next, a polyurethane-based adhesive was applied as the adhesive layer 13 to the surface of the metal foil layer 14 opposite to the metal foil layer 14 of the corrosion prevention treatment layer 15a. Next, the metal foil layer 14 and the corona-treated surface of the base material layer 11 were bonded via the adhesive layer 13 by a dry laminating method. Thereafter, the structure composed of the base material layer 11, the adhesive layer 13, the corrosion prevention treatment layer 15a, the metal foil layer 14, and the corrosion prevention treatment layer 15b is left in an atmosphere at a temperature of 60 ° C. for 6 days, thereby aging. Processed. Thereafter, a total of three types of exterior packaging materials 10 for a power storage device having a dry laminate configuration or a heat laminate configuration were prepared according to the adhesive component forming the sealant adhesive layer 16 as shown below.

-Dry laminate structure Polyurethane system in which polyisocyanate is blended in acid-modified polyolefin dissolved in a mixed solvent of toluene and methylcyclohexane as sealant adhesive layer 16 on the surface opposite to metal foil layer 14 of corrosion prevention treatment layer 15b Adhesive was applied. Next, by a dry laminating method, a 40 μm-thick polyolefin film (a film obtained by corona-treating the surface of the unstretched polypropylene film on the sealant adhesive layer 16 side) and the metal foil layer 14 through the sealant adhesive layer 16. And were adhered. Thereafter, the structure composed of the base material layer 11, the adhesive layer 13, the corrosion prevention treatment layer 15a, the metal foil layer 14, the corrosion prevention treatment layer 15b, the sealant adhesion layer 16, and the sealant layer 17 is placed in an atmosphere having a temperature of 40 ° C. Aging treatment was carried out by leaving it for 6 days. Thereby, the exterior material 10 for power storage devices was produced.
・ Laminate structure (160 ℃ or 200 ℃)
The sealant adhesive layer 16 was formed by extruding maleic anhydride-modified polypropylene (trade name: Admer, manufactured by Mitsui Chemicals), which is a base material of the sealant adhesive layer 16. At this time, the thickness of the sealant adhesive layer 16 was 15 μm. Then, a 30 μm-thick polyolefin film (on the side of the sealant adhesive layer 16 of the unstretched polypropylene film) that becomes the sealant layer 17 is formed on the corrosion prevention layer 15b via the sealant adhesive layer 16 by sandwich lamination instead of the dry lamination method. The film having a corona-treated surface was adhered (heat-pressed) at 160 ° C. or 200 ° C. Thereby, the exterior material 10 for power storage devices was produced.

(Examples 2-4 and 6-8, Comparative Examples 1-5)
An exterior material 10 for a power storage device was produced in the same manner as in Example 1 except that the polyester film shown in Table 1 was used instead of the polyester film of A-1.

(Example 5)
Instead of corona treating one side of the base material layer 11, the easy adhesion treatment layer 12 is formed on the surface of the base material layer 11 on the side of the adhesive layer 13, and the polyester film of A-5 is used instead of the polyester film of A-1 A power storage device exterior material 10 was produced in the same manner as in Example 1 except that a film was used. The easy adhesion treatment layer 12 is coated on one side of the base material layer 11 by using an in-line coating method so that the coating agent serving as a base material of the easy adhesion treatment layer 12 is 0.1 g / m ² in solid content. Then, the easy adhesion treatment layer 12 having a thickness of about 0.1 μm was formed by drying.

Example 9
Instead of forming the corrosion prevention treatment layers 15a and 15b using sodium polyphosphate-stabilized cerium oxide sol, the chromate treatment is performed to form the corrosion prevention treatment layers 15a and 15b, and instead of the polyester film of A-1. A power storage device exterior material 10 was produced in the same manner as in Example 1 except that the polyester film of A-9 was used. The chromate treatment was performed by applying a treatment liquid composed of a phenol resin, a chromium fluoride compound, and phosphoric acid on both surfaces of the metal foil layer 14 to form a film and baking it.

<Evaluation of molding depth>
With respect to each of the three types of external packaging materials for power storage devices 10 produced in each example and comparative example, the molding depth capable of deep drawing was evaluated by the following method. First, the power storage device exterior material 10 was placed in the molding apparatus so that the sealant layer 17 faced upward. The molding depth of the molding apparatus was set to 3.5 to 7.0 mm every 0.5 mm, and cold molding was performed in an environment with a room temperature of 23 ° C. and a dew point temperature of −35 ° C. The punch mold has a rectangular cross section of 70 mm × 80 mm, has a punch radius (RP) of 1.00 mm on the bottom, and a punch corner radius (RCP) of 1.00 mm on the side. It was used. A die mold having a 1.00 mm diradius (RD) on the upper surface of the opening was used. Whether or not there is a break in the cold-formed part and the presence or absence of a pinhole is confirmed visually while irradiating the exterior material 10 with light. The value (molding limit) was determined. The results are shown in Table 2.

<Evaluation of adhesion>
The adhesion between the base material layer 11 and the metal foil layer 14 was evaluated by the following method for the heat storage device exterior material 10 having a heat laminate configuration (160 ° C.) produced in each Example and Comparative Example. First, the power storage device exterior material 10 was placed in the molding apparatus so that the sealant layer 17 faced upward. The molding depth of the molding apparatus was set to 5 mm, and cold molding was performed in an environment with a room temperature of 23 ° C and a dew point temperature of -35 ° C. The punch mold has a rectangular cross section of 70 mm × 80 mm, has a punch radius (RP) of 1.00 mm on the bottom, and a punch corner radius (RCP) of 1.00 mm on the side. It was used. A die mold having a 1.00 mm diradius (RD) on the upper surface of the opening was used.

Next, the cold-molded outer packaging material 10 was placed in a 100 mL capacity beaker containing 30 mL of 1M lithium hexafluorophosphate solution (solvent volume ratio = ethyl carbonate: dimethyl carbonate: dimethyl carbonate = 1: 1: 1). . Next, the beaker containing the exterior material 10 was sealed in a can and placed in a temperature environment of 40 ° C. for 2 hours to expose the exterior material 10 to the electrolytic solution. Then, the exterior material 10 was taken out from the beaker in the Ito can and placed in an oven at 110 ° C. in an environment of temperature 60 ° C. and humidity 95%, or warm water of 50 ° C. Then, after 1 week, 2 weeks, 3 weeks, and 4 weeks, the presence or absence of peeling between the base material layer 11 and the metal foil layer 14 of the outer packaging material 10 was visually confirmed, and the base material layer 11 The maximum value (unit: week) of the period during which no peeling was confirmed between the metal foil layer 14 and the metal foil layer 14 was obtained. Based on the results, the adhesion between the base material layer 11 and the metal foil layer 14 was evaluated according to the following evaluation criteria. The results are shown in Table 2. In addition, about Comparative Examples 3-5, since the shaping | molding limit was less than 5 mm, adhesive evaluation was not performed.
A: No peeling was confirmed even after 4 weeks.
B: Peeling was not confirmed after 3 weeks, but peeling occurred after 4 weeks.

  From the results shown in Table 1, it is understood that according to the present example, excellent deep drawability can be exhibited regardless of the manufacturing process of the exterior material. Furthermore, it is understood that the surface treatment of the metal foil layer is preferably performed using cerium oxide in order to obtain better adhesion regardless of the manufacturing process of the exterior material.

  DESCRIPTION OF SYMBOLS 1 ... Battery element, 2 ... Lead, 10 ... Exterior material (exterior material for power storage device), 11 ... Base material layer, 12 ... Easy adhesion treatment layer, 13 ... Adhesive layer, 14 ... Metal foil layer, 15a, 15b ... Corrosion Prevention treatment layer, 16 ... sealant adhesive layer, 17 ... sealant layer, 30 ... embossed type exterior material, 32 ... molding process area (concave part), 34 ... lid part, 40 ... secondary battery.

Claims (7)

At least a base material layer, an adhesive layer, a metal foil layer, a sealant adhesive layer and a sealant layer have a structure laminated in this order,
The base material layer is a layer made of a polyester film having a ΔA represented by the following formula (1) of 12% or more and a 50% elongation stress value after heat treatment at 200 ° C. of 75 MPa or more. Equipment exterior materials.
ΔA = (breaking elongation after heat treatment at 200 ° C.) − (Breaking elongation after heat treatment at 160 ° C.) (1)
[The elongation at break and the stress value at 50% elongation are respectively tensile tests (test piece shape: JIS K7127) in four directions (0 ° (MD), 45 °, 90 ° (TD), 135 °) of the base material layer. No. 5 type dumbbell shape defined in 1), distance between chucks: 75 mm, distance between gauge points: 25 mm, test speed: 50 mm / min). ]   The packaging material for a power storage device according to claim 1, further comprising an easy adhesion treatment layer provided between the base material layer and the adhesive layer.   The power storage device according to claim 2, wherein the easy adhesion treatment layer is a layer containing at least one resin selected from the group consisting of a polyester resin, an acrylic resin, a polyurethane resin, an epoxy resin, and an acrylic graft polyester resin. Exterior material.   The exterior material for a power storage device according to any one of claims 1 to 3, further comprising a corrosion prevention treatment layer provided on both surfaces of the metal foil layer.   The packaging material for a power storage device according to claim 4, wherein the corrosion prevention treatment layer includes a rare earth element oxide and phosphoric acid or a phosphate.   The power storage device exterior material according to claim 5, wherein the rare earth element oxide is cerium oxide. A battery element including an electrode; a lead extending from the electrode; and a container for holding the battery element while sandwiching the lead.
The said container is an electrical storage apparatus formed from the exterior material for electrical storage apparatuses as described in any one of Claims 1-6 so that the said sealant layer may become an inner side.

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