Exterior material for power storage device

Abstract

To provide an exterior material for a power storage device which is difficult to be deformed even when being pressurized under high temperature environment.SOLUTION: An exterior material for a power storage device includes a base material layer, a barrier layer, a thermal adhesive resin layer or an adhesive layer, and a sealant layer which are laminated in this order, wherein when the thermal adhesive resin and the sealant layer, or the sealant layer is represented by (I), and the base material layer is represented by (II), a loop stiffness value of (I) is 10 mN or more and 80 mN or less, a loop stiffness value of (II) is 2 mN or more and 20 mN or less, a ratio (I / II) in the loop stiffness value of (I) to (II) is 1.0 or more and 15 or less, and a ratio (I / II) in the thickness of (I) to (II) is 1.0 or more and 8.0 or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an exterior material for an electricity storage device. [Background technology]

[0002] Known examples of power storage devices include secondary batteries such as lithium-ion batteries, nickel-metal hydride batteries, and lead-acid batteries, as well as electrochemical capacitors such as electric double-layer capacitors. Due to the miniaturization of portable devices and limitations on installation space, there is a demand for further miniaturization of power storage devices, and lithium-ion batteries with high energy density have attracted attention. While metal cans have traditionally been used as the exterior materials for lithium-ion batteries, multilayer films have begun to be used, which are lightweight, have excellent heat dissipation properties, and can be produced at low cost.

[0003] A lithium ion battery that uses the above multilayer film as an exterior material is called a laminated lithium ion battery. A laminated lithium ion battery includes an energy storage element having a positive electrode, a liquid electrolyte, and a negative electrode, and an exterior bag that houses the energy storage element and prevents moisture from penetrating into the battery. The exterior bag has an exterior material, and the exterior material includes a base layer, a barrier layer, an adhesive layer, and a sealant layer, in that order. The exterior material covers the energy storage element with the sealant layer facing inward and the base layer facing outward. A laminated lithium ion battery is manufactured, for example, by forming a recess in part of the exterior material by cold forming, housing the energy storage element in the recess, folding back the remaining part of the exterior material, and heat-sealing the edges (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-101765 Summary of the Invention [Problem to be solved by the invention]

[0005] Research and development of energy storage devices known as all-solid-state batteries has been underway as next-generation batteries for lithium-ion batteries. An all-solid-state battery includes, for example, an energy storage element and an outer bag housing the energy storage element. In an all-solid-state battery, expansion or contraction of the negative and positive electrodes associated with charging and discharging can cause delamination between the solid electrolyte and the positive electrode active material, or between the solid electrolyte and the negative electrode active material. This can result in insufficient output from the all-solid-state battery. Therefore, unlike liquid lithium-ion batteries, to improve the output of an all-solid-state battery, the energy storage element may be pressurized via the outer bag. However, if excessive deformation of the outer bag occurs due to the pressurization, uniform pressure may not be applied to the energy storage element via the outer bag.

[0006] Here, the temperature range of an all-solid-state battery is, for example, from -40°C to 100°C. This range is wider than the temperature range of a liquid lithium-ion battery (for example, from -40°C to 60°C). When an all-solid-state battery is used that is pressurized by an outer bag in a high-temperature environment (for example, 70°C or higher) in order to improve the output of the all-solid-state battery, the above-mentioned deformation of the outer bag is likely to occur. Therefore, even when an all-solid-state battery is used in a high-temperature environment, the output of the all-solid-state battery may be insufficient.

[0007] An object of one aspect of the present disclosure is to provide an exterior material for an electricity storage device that is resistant to excessive deformation even when pressurized in a high-temperature environment. [Means for solving the problem]

[0008] An exterior packaging material for an electricity storage device according to one aspect of the present disclosure comprises a base material layer, a barrier layer, a thermal adhesive resin layer or adhesive layer, and a sealant layer, which are laminated in this order; when the thermal adhesive resin layer and the sealant layer, or the sealant layer, are (I) and the base material layer is (II), the loop stiffness value of (I) is 10 mN or more and 80 mN or less, the loop stiffness value of (II) is 2 mN or more and 20 mN or less, the ratio of the loop stiffness values ​​of (I) and (II) (I / II) is 1.0 or more and 15 or less, and the thickness ratio of (I) to (II) (I / II) is 1.0 or more and 8.0 or less.

[0009] According to the electrical storage device packaging material, the ratio (I / II) of the loop stiffness values ​​of (I) and (II) is 1.0 or more and 15 or less, and the ratio (I / II) of the thicknesses of (I) and (II) is 1.0 or more and 8.0 or less. By satisfying these parameters, an electrical storage device packaging material that is resistant to excessive deformation even when pressurized in a high-temperature environment is provided.

[0010] The thickness of (I) may be 30 μm or more and 120 μm or less, and the thickness of (II) may be 10 μm or more and 60 μm or less. In this case, the durability of the packaging material can be ensured while keeping the thickness of the packaging material small. In addition, the loop stiffness value of (I) and the loop stiffness value of (II) can be reliably set within the above ranges.

[0011] The ratio (I / II) of the loop stiffness values ​​of (I) and (II) may be 2.5 or more and 11.0 or less, in which case deformation of the exterior packaging material for an electricity storage device is further suppressed even when pressure is applied in a high-temperature environment.

[0012] The ratio (I / II) of the loop stiffness values ​​of (I) and (II) may be 3.5 or more and 10 or less. In this case, deformation of the exterior packaging material for an electricity storage device is more effectively suppressed even when pressure is applied in a high-temperature environment.

[0013] The sealant layer may contain a polypropylene-based resin as a base resin, and the polypropylene-based resin may be composed of homopropylene or block polypropylene, in which case melting of the sealant layer in a high-temperature environment can be suppressed.

[0014] The sealant layer may further contain an additive resin containing a polyethylene-based resin or a block copolymer compatible with the polypropylene-based resin, in which case deformation of the electrical storage device packaging material is further suppressed.

[0015] The sealant layer may further include an additive resin containing a polyethylene-based resin, and a compatibilizer having a portion compatible with the polypropylene-based resin and a portion compatible with the polyethylene-based resin, in which case deformation of the electrical storage device packaging material is more effectively suppressed.

[0016] The compatibilizer may include a block copolymer of polypropylene and polyethylene, or a block copolymer of polyethylene and polyethylenebutylene.

[0017] The packaging material for an electricity storage device may be a packaging material for an all-solid-state battery. The packaging material for an electricity storage device is highly suitable as a packaging material for an all-solid-state battery because it can suppress deformation even when pressurized in a high-temperature environment. [Effects of the Invention]

[0018] According to the present disclosure, it is possible to provide an exterior packaging material for an electricity storage device that is resistant to excessive deformation even when pressurized in a high-temperature environment. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a schematic cross-sectional view of an exterior packaging material for an electricity storage device according to one embodiment. [Figure 2] FIG. 2 is a perspective view showing an electricity storage device according to one embodiment. [Figure 3]FIG. 3(a) is a schematic cross-sectional view of a comparative exterior material when pressed against a rigid body, and FIG. 3(b) is a schematic cross-sectional view of an exterior material for an electricity storage device according to one embodiment when pressed against a rigid body. [Figure 4] FIG. 4 is a schematic cross-sectional view of an exterior packaging material for an electricity storage device according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0020] Preferred embodiments of the present disclosure will be described in detail below with reference to the drawings. In the drawings, identical or corresponding parts are designated by the same reference numerals, and duplicate explanations will be omitted. Furthermore, the dimensional ratios of the drawings are not limited to those shown.

[0021] [Exterior materials for energy storage devices] FIG. 1 is a schematic cross-sectional view of an electrical storage device packaging material according to one embodiment. As shown in FIG. 1, packaging material 10 (electrical storage device packaging material) according to one embodiment is a packaging material used in an electrical storage device, and includes, in this order, a base material layer 11, a barrier layer 13, a thermal adhesive resin layer 15, and a sealant layer 16. If a laminate of thermal adhesive resin layer 15 and sealant layer 16 is designated as (I) and base material layer 11 is designated as (II), the loop stiffness value of (I) is 10 mN or more and 80 mN or less, the loop stiffness value of (II) is 2 mN or more and 20 mN or less, the ratio of the loop stiffness values ​​of (I) and (II) (I / II) is 1.0 or more and 15 or less, and the thickness ratio of (I) to (II) (I / II) is 1.0 or more and 8.0 or less. This packaging material 10 can suppress deformation even when pressure is applied in a high-temperature environment.

[0022] In one embodiment, in packaging material 10, barrier layer 13 has first corrosion prevention treatment layer 14a on the substrate layer 11 side via first adhesive layer 12a, and has second corrosion prevention treatment layer 14b on the sealant layer 16 side. When packaging material 10 is used as an exterior bag for an electricity storage device, substrate layer 11 is the outermost layer and sealant layer 16 is the innermost layer in packaging material 10. In other words, packaging material 10 is used with substrate layer 11 facing outward from the electricity storage device and sealant layer 16 facing inward from the electricity storage device.

[0023] Each layer that constitutes the packaging material 10 will now be described in detail.

[0024] <Base material layer> The base material layer 11 provides heat resistance in the sealing process when manufacturing the electricity storage device and plays a role in suppressing the occurrence of pinholes that may occur during molding, processing, and distribution. In particular, in the case of an exterior material for a large-scale electricity storage device, the base material layer 11 can also provide scratch resistance, chemical resistance, insulating properties, etc.

[0025] The base layer 11 is preferably a layer formed of an insulating resin, such as polyester resin, polyamide resin, polyimide resin, polyamideimide resin, polyetherketone resin, polyphenylene sulfide resin, polyetherimide resin, polysulfone resin, fluororesin, phenol resin, melamine resin, urethane resin, allyl resin, silicone resin, epoxy resin, furan resin, or acetyl cellulose resin.

[0026] Among these resins, polyester resins and polyamide resins are preferred for the base layer 11 because of their excellent moldability. Examples of polyester resins include polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate. Examples of polyamide resins include nylon 6, nylon 6,6, a copolymer of nylon 6 and nylon 6,6, nylon 9T, nylon 10, polymetaxylylene adipamide (MXD6), nylon 11, and nylon 12.

[0027] The substrate layer 11 may be in the form of a stretched or unstretched film, or in the form of a coating film. The substrate layer 11 may be a single layer or a multilayer. When the substrate layer 11 is a multilayer, it is formed by laminating layers made of different resins. When the substrate layer 11 is in the form of a film, a co-extruded film or a film laminated with an adhesive can be used. When the substrate layer 11 is a coating film, a coating film obtained by applying a coating film-forming composition multiple times can be used. The substrate layer 11 can also be multilayered by combining a film and a coating film.

[0028] When the above-mentioned resin is used in the form of a film, the base material layer 11 is preferably a biaxially stretched film. In this case, the molding property of the packaging material 10 is improved. Examples of the stretching method for the biaxially stretched film include sequential biaxial stretching, tubular biaxial stretching, and simultaneous biaxial stretching. From the viewpoint of obtaining better deep-draw moldability, the biaxially stretched film is preferably a film stretched by the tubular biaxial stretching method.

[0029] The thickness of the base layer 11 is 10 μm or more and 60 μm or less. The thickness of the base layer 11 may be 15 μm or more, 20 μm or more, 25 μm or more, 50 μm or less, 40 μm or less, or 35 μm or less. When the thickness of the base layer 11 is within the above range, it is easy to control the loop stiffness value of the base layer 11 within a suitable range.

[0030] From the viewpoint of stiffness and thermal deformation resistance of the packaging material 10, the loop stiffness value of the base material layer 11 is 2 mN or more and 20 mN or less. The loop stiffness value of the base material layer 11 may be 2.5 mN or more and 17 mN or less, 3 mN or more and 15 mN or less, or 4.5 mN or more and 14.5 mN or less. The loop stiffness value of the base material layer 11 corresponds to the stress when the base material layer 11 is bent into a loop shape and compressed in the diameter direction of the loop. Generally, the higher the loop stiffness value of a film, the stronger the stiffness of the film. The loop stiffness value of the base material layer 11 can be obtained, for example, by a loop stiffness tester described in the examples below.

[0031] <First adhesive layer> The first adhesive layer 12a is a layer that bonds the base material layer 11 and the barrier layer 13. Specific examples of materials that constitute the first adhesive layer 12a include polyurethane resins in which a bifunctional or higher isocyanate compound (a polyfunctional isocyanate compound) acts as a curing agent on a base material such as polyester polyol, polyether polyol, acrylic polyol, or carbonate polyol. The various polyols described above can be used alone or in combination of two or more types depending on the functions and performance required of the packaging material 10. In addition to the above, materials that can be used to constitute the first adhesive layer 12a include those that use epoxy resin as a base material and a curing agent.

[0032] The first adhesive layer 12a is formed using an adhesive composition containing the above-mentioned base agent and curing agent. Furthermore, the first adhesive layer 12a may contain various other additives and stabilizers in the above-mentioned adhesive composition depending on the performance required of the adhesive layer. Examples of additives include a tin-based, titanium-based, or zirconium-based urethane catalyst to accelerate curing, and a latent curing agent or a latent curing agent. Examples of latent curing agents include amine-based compounds. These may be used alone or in combination.

[0033] The adhesive composition preferably contains, as a curing agent, at least one polyfunctional isocyanate compound selected from the group consisting of alicyclic isocyanate polymers and isocyanate polymers containing an aromatic ring in the molecular structure. Examples of polyfunctional isocyanate compounds include nurate forms of isophorone diisocyanate, adduct forms of tolylene diisocyanate, adduct forms of hexamethylene diisocyanate, biuret forms and nurate forms of hexamethylene diisocyanate, biuret forms and nurate forms of tolylene diisocyanate, adduct forms, biuret forms and nurate forms of diphenylmethane diisocyanate, and adduct forms, biuret forms and nurate forms of xylylene diisocyanate.

[0034] As the curing agent, an alicyclic isocyanate polymer and an isocyanate polymer containing an aromatic ring in the molecular structure may be used in combination. By using these in combination, heat resistance tends to be further improved.

[0035] From the viewpoint of further improving heat resistance, the adhesive composition preferably contains at least one polyol selected from the group consisting of polyester polyol, acrylic polyol, and polycarbonate diol, and among these, polyester polyol is more preferred from the viewpoint of further improving heat resistance.

[0036] In the adhesive composition, the ratio of the number of isocyanate groups contained in the polyfunctional isocyanate compound to the number of hydroxyl groups contained in the polyol (NCO / OH) may be 1.5 or more and 40.0 or less, or 15.0 or more and 30.0 or less. If this ratio is 1.5 or more, the curing agents react with each other, easily producing by-products such as urea resins and biuret resins. These by-products contain active hydrogen groups, which interact with polar groups in adjacent layers, further improving the interfacial adhesion between the first adhesive layer 12a and the substrate layer 11 and the barrier layer 13. This tends to improve the heat resistance of the packaging material 10. On the other hand, if the ratio is 40.0 or less, the laminate strength of the packaging material 10 can be further improved in room temperature and high temperature environments.

[0037] The thickness of the first adhesive layer 12a is not particularly limited, but is, for example, 1 μm or more and 10 μm or less, or 2 μm or more and 7 μm or less, from the viewpoint of obtaining the desired adhesive strength, followability, processability, etc.

[0038] The mass per unit area of ​​the first adhesive layer 12a is set to 2.0 g / m from the viewpoint of ensuring superior lamination strength both in room temperature and high temperature environments and obtaining superior deep drawability. 2 More than 6.0g / m 2 may be less than or equal to 2.5 g / m 2 More than 5.0g / m 2 It may be 3.0 g / m or less. 2 More than 4.0g / m 2 It may be the following:

[0039] <Barrier layer> The barrier layer 13 has water vapor barrier properties that prevent moisture from penetrating into the interior of the electricity storage device. The barrier layer 13 may also have extensibility for deep drawing. Examples of the barrier layer 13 that can be used include various metal foils such as aluminum, stainless steel, and copper, as well as metal vapor-deposited films, inorganic oxide vapor-deposited films, carbon-containing inorganic oxide vapor-deposited films, and films having these vapor-deposited films. Examples of films having vapor-deposited films that can be used include aluminum vapor-deposited films and inorganic oxide vapor-deposited films. These may be used alone or in combination of two or more. In terms of mass (specific gravity), barrier properties such as moisture resistance, processability, and cost, metal foils are preferred for the barrier layer 13, and aluminum foil or stainless steel foil is more preferred.

[0040] As the aluminum foil, soft aluminum foil that has been annealed is particularly preferred because it can impart the desired ductility during molding. To further impart pinhole resistance and ductility during molding, it is more preferable to use aluminum foil containing iron. The iron content in the aluminum foil is preferably 0.1% by mass or more and 9.0% by mass or less, and more preferably 0.5% by mass or more and 2.0% by mass or less, based on 100% by mass of the aluminum foil. By having an iron content of 0.1% by mass or more, an exterior packaging material 10 having better pinhole resistance and ductility can be obtained. By having an iron content of 9.0% by mass or less, an exterior packaging material 10 having better flexibility can be obtained. Untreated aluminum foil may be used as the aluminum foil, but it is preferable to use aluminum foil that has been degreased in order to impart corrosion resistance. When degreasing the aluminum foil, the degreasing treatment may be performed on only one side of the aluminum foil, or on both sides.

[0041] The thickness of the barrier layer 13 is not particularly limited, but taking into consideration the barrier properties, pinhole resistance, and processability, it is preferably 9 μm or more and 200 μm or less, more preferably 15 μm or more and 100 μm or less, even more preferably 30 μm or more and 80 μm or less, and particularly preferably 40 μm or more and 60 μm or less.

[0042] <First and second corrosion prevention treatment layers> The first and second corrosion prevention treatment layers 14a, 14b are layers provided to prevent corrosion of the metal foil (metal foil layer) that constitutes the barrier layer 13. The first corrosion prevention treatment layer 14a serves to increase the adhesion between the barrier layer 13 and the first adhesive layer 12a. The second corrosion prevention treatment layer 14b serves to increase the adhesion between the barrier layer 13 and the thermal adhesive resin layer 15. The first corrosion prevention treatment layer 14a and the second corrosion prevention treatment layer 14b may be layers of the same configuration or layers of different configurations. The first and second corrosion prevention treatment layers 14a, 14b (hereinafter simply referred to as "corrosion prevention treatment layers 14a, 14b") are formed, for example, by degreasing, hydrothermal conversion treatment, anodizing, chemical conversion treatment, or a combination of these treatments.

[0043] Examples of degreasing treatments include acid degreasing and alkaline degreasing. Acid degreasing methods include using inorganic acids such as sulfuric acid, nitric acid, hydrochloric acid, and hydrofluoric acid, either singly or in combination. For acid degreasing, it is preferable to use an acid degreasing agent prepared by dissolving a fluorine-containing compound such as monosodium ammonium difluoride in the inorganic acid. In this case, the aluminum degreasing effect can be achieved, particularly when an aluminum foil is used for the barrier layer 13. Furthermore, acid degreasing agents can form aluminum fluorides, which are passive, and are therefore effective in terms of corrosion resistance. Alkaline degreasing methods include using sodium hydroxide or the like.

[0044] An example of the hydrothermal modification treatment is boehmite treatment, in which aluminum foil is immersed in boiling water containing triethanolamine. An example of the anodization treatment is alumite treatment.

[0045] The chemical conversion treatment may be an immersion type or a coating type. Examples of the immersion type chemical conversion treatment include chromate treatment, zirconium treatment, titanium treatment, vanadium treatment, molybdenum treatment, calcium phosphate treatment, strontium hydroxide treatment, cerium treatment, ruthenium treatment, and various chemical conversion treatments consisting of a mixture of these. On the other hand, an example of the coating type chemical conversion treatment is a method in which a coating agent having corrosion prevention properties is applied to the barrier layer 13.

[0046] When forming at least a part of the corrosion prevention treatment layer by any of these corrosion prevention treatments, i.e., hydrothermal conversion treatment, anodizing treatment, or chemical conversion treatment, it is preferable to perform the degreasing treatment described above beforehand. Note that when a degreased metal foil, such as a metal foil that has been subjected to an annealing process, is used as the barrier layer 13, there is no need to perform a degreasing treatment again when forming the corrosion prevention treatment layers 14a and 14b.

[0047] The coating agent used in the spray-type chemical conversion treatment preferably contains trivalent chromium and may also contain at least one polymer selected from the group consisting of cationic polymers and anionic polymers, which will be described later.

[0048] Among the above treatments, hydrothermal conversion treatment and anodizing, in particular, dissolve the aluminum foil surface with a treatment agent to form aluminum compounds (boehmite, anodized aluminum) with excellent corrosion resistance. Therefore, a bicontinuous structure is formed from the aluminum foil barrier layer 13 to the corrosion prevention treatment layers 14a, 14b, and therefore these treatments are included in the definition of chemical conversion treatment. On the other hand, as described below, it is also possible to form the corrosion prevention treatment layers 14a, 14b using a pure coating method, which is not included in the definition of chemical conversion treatment. One example of such a method is the use of a sol of a rare earth oxide, such as cerium oxide, with an average particle size of 100 nm or less, which has an aluminum corrosion prevention effect (inhibitor effect) and is environmentally friendly. Using this method, it is possible to impart corrosion prevention effects to metal foils such as aluminum foil using a conventional coating method.

[0049] Examples of the rare earth element oxide sol include sols using various solvents such as water-based, alcohol-based, hydrocarbon-based, ketone-based, ester-based, ether-based, etc. Of these, water-based sols are preferred.

[0050] In order to stabilize the dispersion of the rare earth element oxide sol, inorganic acids such as nitric acid, hydrochloric acid, phosphoric acid, etc. or their salts, and organic acids such as acetic acid, malic acid, ascorbic acid, lactic acid, etc. are usually used as dispersion stabilizers. Among these dispersion stabilizers, phosphoric acid in particular is expected to have the following effects (1) to (4) in the packaging material 10. (1) Dispersion stabilization of sol (2) Improved adhesion to the barrier layer 13 by utilizing the aluminum chelating ability of phosphoric acid (3) Imparting corrosion resistance by capturing aluminum ions (passivation) (4) Improvement of the cohesive strength of the corrosion prevention treatment layers (oxide layers) 14a and 14b due to the tendency of dehydration condensation of phosphoric acid to occur even at low temperatures.

[0051] Since the corrosion prevention treatment layers 14a, 14b formed from the rare earth element oxide sol are aggregates of inorganic particles, the cohesive strength of the layers themselves may be reduced even after the dry-cure process. Therefore, in this case, the corrosion prevention treatment layers 14a, 14b are preferably compounded with an anionic polymer or a cationic polymer to compensate for the cohesive strength.

[0052] The corrosion prevention treatment layers 14a, 14b are not limited to the layers described above. For example, they may be formed using a treatment agent that combines phosphoric acid and a chromium compound with a resin binder (such as aminophenol), as in the case of a known paint-type chromate. Using this treatment agent makes it possible to obtain a layer that combines both corrosion prevention functionality and adhesion. Furthermore, although the stability of the coating liquid must be considered, a coating agent that combines a rare earth element oxide sol with a polycationic polymer or a polyanionic polymer in advance as a one-component can be used to obtain a layer that combines corrosion prevention functionality and adhesion.

[0053] The mass per unit area of ​​the corrosion prevention treatment layers 14a and 14b is 0.005 g / m2 regardless of whether the layer has a multi-layer structure or a single-layer structure. 2 More than 0.200g / m 2 Preferably, it is 0.010 g / m or less. 2 More than 0.100g / m 2 It is more preferable that the mass per unit area is 0.005 g / m or less. 2 If the mass per unit area is 0.200 g / m or more, it is easy to impart a corrosion prevention function to the barrier layer 13. 2 Even if the thickness exceeds this range, the corrosion prevention function does not change significantly. On the other hand, when a rare earth element oxide sol is used, if the coating is thick, the heat curing during drying may be insufficient, which may result in a decrease in cohesive force. The thickness of the corrosion prevention treatment layers 14a and 14b can be calculated from their specific gravity.

[0054] From the viewpoint of easily maintaining adhesion between the sealant layer 16 and the barrier layer 13, the corrosion prevention treatment layers 14a, 14b may be in an embodiment containing, for example, cerium oxide, phosphoric acid or a phosphate in an amount of 1 part by mass or more and 100 parts by mass or less per 100 parts by mass of the cerium oxide, and a cationic polymer, or may be in an embodiment formed by subjecting the barrier layer 13 to a chemical conversion treatment, or may be in an embodiment formed by subjecting the barrier layer 13 to a chemical conversion treatment and containing a cationic polymer.

[0055] <Sealant layer and thermal adhesive resin layer> The sealant layer 16 is a layer that provides heat-sealing properties to the packaging material 10, and is placed on the inside and heat-sealed (thermally fused) when assembling the electricity storage device. The thermal adhesive resin layer 15 is a layer that bonds the sealant layer 16 and the barrier layer 13 together, and contains an adhesive resin.

[0056] In one embodiment, the sealant layer 16 includes a polypropylene-based resin as a base resin. The polypropylene-based resin is a resin obtained from a polymerized monomer containing propylene. Examples of the polypropylene-based resin include homopolypropylene, block polypropylene, and random polypropylene. These may be used alone or in combination of two or more. From the viewpoint of stiffness of the sealant layer 16, the polypropylene-based resin may include at least one of homopolypropylene and block polypropylene.

[0057] The content of the polypropylene resin in the sealant layer 16 is not particularly limited and is, for example, 30% by mass or more and 100% by mass or less. From the viewpoint of stiffness of the sealant layer 16, the content may be 50% by mass or more and 95% by mass or less, or 70% by mass or more and 90% by mass or less.

[0058] In addition to the base resin, the sealant layer 16 may contain an additive resin containing a polyethylene-based resin or a block copolymer compatible with polypropylene-based resins. Polyethylene-based resins are resins obtained from polymerized monomers containing ethylene and serve to impart softness (stress relaxation properties). Examples of polyethylene-based resins include low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), and polyethylene-based elastomers. These may be used alone or in combination of two or more. Since polyethylene-based resins can particularly impart softness, it is preferable for them to contain a polyethylene-based elastomer. The block copolymer compatible with polypropylene-based resins is sufficient as long as it is compatible with at least polypropylene-based resins, and may be, for example, one type of compatibilizer described below.

[0059] The polyethylene elastomer may be an elastomer containing an α-olefin as a comonomer, specifically, a compound obtained by copolymerizing ethylene with at least one α-olefin selected from 1-butene, 1-pentene, 1-hexene, 1-octene, and 4-methyl-1-pentene.

[0060] When the sealant layer 16 contains a polyethylene-based resin as an additive resin, the content of the polyethylene-based resin in the sealant layer 16 is not particularly limited and is, for example, 1% by mass to 70% by mass. From the viewpoint of stiffness of the sealant layer 16, the content may be 5% by mass to 50% by mass, 10% by mass to 30% by mass, or 10% by mass to 20% by mass. When the sealant layer 16 contains a block copolymer that is compatible with the polypropylene-based resin, the content of the block copolymer in the sealant layer 16 is not particularly limited and is, for example, 1% by mass to 70% by mass. From the viewpoint of stiffness of the sealant layer 16, the content may be 5% by mass to 50% by mass, 10% by mass to 30% by mass, or 10% by mass to 20% by mass.

[0061] The sealant layer 16 may contain, in addition to the base resin, the additive resin and a compatibilizer. The compatibilizer efficiently imparts softness by finely dispersing the polyethylene resin in the base resin made of the polypropylene resin. In one embodiment, the compatibilizer has a portion compatible with the polypropylene resin (hereinafter also referred to as the "PP compatible portion") and a portion compatible with the polyethylene resin (hereinafter also referred to as the "PE compatible portion"). Specific examples of the compatibilizer include a graft copolymer in which the PP compatible portion is the main chain and the PE compatible portion is the side chain, a graft copolymer in which the PE compatible portion is the main chain and the PP compatible portion is the side chain, and a block copolymer in which the PP compatible portion and the PE compatible portion each exist as a block. From the viewpoint of improving the dispersibility of the compatibilizer, the compatibilizer may be a block copolymer in which at least the PP compatible portion exists as a block, or a block copolymer in which the PP compatible portion and the PE compatible portion each exist as a block. Examples of such block copolymers include polypropylene and polyethylene block copolymers (PP·PE block copolymers) and polyethylene and polyethylene butylene block copolymers (PE·PE-butylene block copolymers). In PE·PE-butylene block copolymers, the butylene portion corresponds to the PP compatible site.

[0062] The content of the compatibilizer in the sealant layer 16 is not particularly limited and is, for example, 1% by mass to 50% by mass. From the viewpoint of stiffness of the sealant layer 16, the content may be 2% by mass to 30% by mass, 5% by mass to 15% by mass, or 6% by mass to 10% by mass.

[0063] The total content of the additive resin containing the polyethylene resin and the compatibilizer in the sealant layer 16 may be 1% by mass or more and 70% by mass or less, 2% by mass or more and 50% by mass or less, or 5% by mass or more and 30% by mass or less.

[0064] The mass ratio of the compatibilizer to the additive resin containing a polyethylene resin is, for example, 5:1 to 1:5 (additive resin containing a polyethylene resin: compatibilizer), and may be 2:1 to 1:4 or 1:1.1 to 1:3.

[0065] The sealant layer 16 may contain other additive components as needed, such as slip agents, antiblocking agents, antioxidants, light stabilizers, crystal nucleating agents, flame retardants, etc. The content of these additive components is, for example, 5% by mass or less, assuming that the total mass of the sealant layer 16 is 100% by mass.

[0066] The thermal adhesive resin layer 15 is not particularly limited as long as it contains a resin that bonds the sealant layer 16 and the barrier layer 13 together, and examples of such resins include acid-modified polyolefin resins.

[0067] The acid-modified polyolefin resin may be a polyolefin resin modified with maleic anhydride, carboxylic acid, sulfonic acid, or a derivative thereof. The acid-modified polyolefin resin may be, for example, a graft copolymer, a block copolymer, or a random copolymer. From the viewpoint of adhesion to the barrier layer 13, the acid-modified polyolefin resin is preferably a polyolefin resin graft-modified with maleic anhydride.

[0068] The thermal adhesive resin layer 15 may contain various additives, such as various compatible and incompatible elastomers, flame retardants, slip agents, antiblocking agents, antioxidants, light stabilizers, nucleating agents, and tackifiers, as needed.

[0069] The ratio of the thickness of the sealant layer 16 to the thickness of the thermal adhesive resin layer 15 (thickness of sealant layer 16 / thickness of thermal adhesive resin layer 15) is preferably 1 or more, more preferably 1.1 or more, and even more preferably 1.5 or more. The ratio of the thickness of the sealant layer 16 to the thickness of the thermal adhesive resin layer 15 (thickness of sealant layer 16 / thickness of thermal adhesive resin layer 15) is preferably 10 or less, more preferably 3 or less, and even more preferably 2.2 or less.

[0070] As described below, the sealant layer 16 and the thermal adhesive resin layer 15 are formed simultaneously, making separation of the sealant layer 16 and the thermal adhesive resin layer 15 difficult. Therefore, in one embodiment, the physical properties of the innermost layer of the packaging material 10 are considered to be the physical properties of a laminate of the sealant layer 16 and the thermal adhesive resin layer 15. The total thickness of the sealant layer 16 and the thermal adhesive resin layer 15 (i.e., the thickness of the laminate) is greater than the thickness of the base material layer 11, which is the outermost layer of the packaging material 10, and is 30 μm or more and 120 μm or less. The thickness of the laminate may be 45 μm or more and 100 μm or less, 65 μm or more and 85 μm or less, or 70 μm or more and 80 μm or less. By keeping the total thickness of the sealant layer 16 and the thermal adhesive resin layer 15 within the above range, it is easy to control the loop stiffness value of the laminate within a suitable range. Additionally, pinholes can be prevented from occurring in the sealant layer 16, thereby reducing the risk of breakage of the packaging material 10. The loop stiffness value of the laminate is, for example, 10 mN or more and 80 mN or less. The loop stiffness value of the laminate may be greater than the loop stiffness value of the base material layer 11. The loop stiffness value may be 15 mN or more, 25 mN or more, 35 mN or more, 40 mN or more, 80 mN or less, 70 mN or less, 60 mN or less, 50 mN or less, or 45 mN or less.

[0071] In one embodiment, when the laminate of the sealant layer 16 and the thermal adhesive resin layer 15 is (I) and the base layer 11 is (II), the ratio of the thicknesses of (I) and (II) (I / II) is 1.0 or more and 8.0 or less. In addition, the ratio of the loop stiffness values ​​of (I) and (II) (I / II) is, for example, 1.0 or more and 15 or less. In this case, the hardness (stiffness) of (I) and the hardness (stiffness) of (II) are well balanced. Therefore, when pressure is applied from the base layer 11 toward the sealant layer 16 while the sealant layer 16 is in close contact with the electricity storage device, the pressure can be uniformly distributed at the stage of being transmitted to the electricity storage device.

[0072] The ratio (I / II) of the thickness of (I) to that of (II) may be 1.5 or more and 6.5 or less, 2.0 or more and 5.0 or less, or 2.3 or more and 3.2 or less. The ratio (I / II) of the loop stiffness value of (I) to that of (II) may be 2.5 or more and 11.0 or less, 3.0 or more and 11.0 or less, 3.5 or more and 10 or less, 7.0 or more and 10 or less, 7.5 or more and 9.0 or less, 8.0 or more and 10.0 or less, or 8.0 or more and 8.7 or less.

[0073] Fig. 2 is a perspective view showing an electricity storage device according to an embodiment of the present disclosure. As shown in Fig. 2, an all-solid-state battery 50 as an electricity storage device includes an electricity storage element 52, two metal terminals (current extraction terminals) 53 for extracting current from the electricity storage element 52 to the outside, and an exterior bag 54 for hermetically housing the electricity storage element 52.

[0074] The exterior bag 54 is formed using the exterior material 10 to have a bag main body 54a and a seal portion 54b provided on the bag main body 54a, and is used as a container for accommodating the energy storage element 52. In the exterior material 10, the base material layer 11 is the outermost layer, and the sealant layer 16 is the innermost layer. That is, the exterior bag 54 can accommodate the energy storage element 52 inside by folding one exterior material 10 in half and heat-sealing the peripheral portions, or by stacking two exterior materials 10 and heat-sealing the peripheral portions, so that the base material layer 11 is on the outside of the all-solid-state battery 50 and the sealant layer 16 is on the inside of the all-solid-state battery 50.

[0075] The metal terminal 53 is sandwiched by an exterior bag 54 with the sealant layer 16 on the inside. The metal terminal 53 may be sandwiched by the exterior bag 54 via a tab sealant. The metal terminal 53 is a part of the current collector that is taken out to the outside of the exterior material 10, and is made of a metal foil such as copper foil or aluminum foil.

[0076] The energy storage element 52 has a pair of electrodes and a solid electrolyte sandwiched between the pair of electrodes. One of the pair of electrodes is a positive electrode, and the other is a negative electrode. Examples of the solid electrolyte include a sulfide-based solid electrolyte and an oxide-based solid electrolyte.

[0077] [Exterior material manufacturing method] Next, a description will be given of an example of a method for manufacturing the packaging material 10 shown in Fig. 1. Note that the method for manufacturing the packaging material 10 is not limited to the following method.

[0078] A manufacturing method of an exterior material 10 of one embodiment is generally composed of the steps of providing corrosion prevention treatment layers 14a, 14b on a barrier layer 13, bonding the base material layer 11 and the barrier layer 13 together using a first adhesive layer 12a, further laminating a thermal adhesive resin layer 15 and a sealant layer 16 on the surface of the barrier layer 13 facing the corrosion prevention treatment layer 14b, and, if necessary, performing an aging treatment.

[0079] (Laminating process of corrosion prevention treatment layer onto barrier layer) This step is a step of forming corrosion prevention treatment layers 14a and 14b on the barrier layer 13. As described above, examples of the method for forming the corrosion prevention treatment layers 14a and 14b include degreasing treatment, hydrothermal treatment, anodizing treatment, and chemical conversion treatment on the barrier layer 13, and applying a coating agent having corrosion prevention properties.

[0080] Furthermore, when the corrosion prevention treatment layers 14a, 14b are multi-layered, for example, the coating liquid (coating agent) constituting the lower corrosion prevention treatment layer (barrier layer 13 side) may be applied to the barrier layer 13 and baked to form a first layer, and then the coating liquid (coating agent) constituting the upper corrosion prevention treatment layer may be applied to the first layer and baked to form a second layer.

[0081] Degreasing treatment can be performed by spraying or immersion. Hydrothermal conversion treatment and anodizing treatment can be performed by immersion. Chemical conversion treatment can be performed by immersion, spraying, coating, or other methods appropriately selected depending on the type of chemical conversion treatment.

[0082] As a method for applying a coating agent having corrosion prevention properties, various methods such as gravure coating, reverse coating, roll coating, and bar coating can be used.

[0083] As described above, the various treatments for the barrier layer 13 may be applied to either one or both sides of the metal foil, but in the case of one-side treatment, the treated side is preferably the side on which the sealant layer 16 is laminated. If desired, the surface of the base layer 11 may also be subjected to the above treatments.

[0084] The coating amount of the coating agent for forming the first layer and the second layer was 0.005 g / m 2 More than 0.200g / m 2 Preferably, it is 0.010 g / m or less. 2 More than 0.100g / m 2 More preferably, it is:

[0085] Furthermore, if dry curing is required, it can be performed at a base material temperature in the range of 60° C. to 300° C., depending on the drying conditions of the corrosion prevention treatment layers 14a and 14b used.

[0086] (Step of bonding the substrate layer and the barrier layer) This step is a step of bonding the barrier layer 13 provided with the corrosion prevention treatment layers 14a and 14b to the substrate layer 11 via the first adhesive layer 12a. The substrate layer 11 is bonded to the surface of the barrier layer 13 on the corrosion prevention treatment layer 14a side. The bonding method may be dry lamination, non-solvent lamination, wet lamination, or the like, and the two are bonded together using the material that constitutes the first adhesive layer 12a described above. The first adhesive layer 12a is preferably applied in a dry coating amount of 1 g / m 2 More than 10g / m 2 the following range, more preferably 2 g / m 2 More than 7g / m 2 It is set within the following range.

[0087] (Laminating process of thermal adhesive resin layer and sealant layer) The lamination process for the thermal adhesive resin layer and the sealant layer is a process for forming the thermal adhesive resin layer 15 and the sealant layer 16 on the surface of the barrier layer 13 facing the corrosion prevention treatment layer 14b. Examples of methods for this include sand lamination of the thermal adhesive resin layer 15 together with the sealant layer 16 using an extrusion laminator. Furthermore, lamination can also be performed using a tandem lamination method or a co-extrusion method in which the thermal adhesive resin layer 15 and the sealant layer 16 are extruded. When forming the thermal adhesive resin layer 15 and the sealant layer 16, for example, the components are blended so as to satisfy the above-described structures of the thermal adhesive resin layer 15 and the sealant layer 16. The thermal adhesive resin layer 15 is formed using a resin composition for forming a thermal adhesive resin layer containing the above-described components of the thermal adhesive resin layer 15. The sealant layer 16 is formed using a resin composition for forming a sealant layer containing the above-described components of the sealant layer 16.

[0088] The lamination process of the thermal adhesive resin layer and the sealant layer results in a laminated structure in which the layers are laminated in the order of base material layer 11 / first adhesive layer 12a / first corrosion prevention treatment layer 14a / barrier layer 13 / second corrosion prevention treatment layer 14b / thermal adhesive resin layer 15 / sealant layer 16, as shown in Figure 1.

[0089] The thermal adhesive resin layer 15 may be formed by directly extruding dry-blended materials using an extrusion laminator to form the above-mentioned material composition. Alternatively, the thermal adhesive resin layer 15 may be formed by extruding granules obtained by previously melt-blending the materials using a melt kneading device such as a single-screw extruder, a twin-screw extruder, or a Brabender mixer, and then extruding the granules using an extrusion laminator.

[0090] The sealant layer 16 may be laminated by directly extruding a material obtained by dry-blending the components of the resin composition for forming a sealant layer using an extrusion laminator. Alternatively, the thermal adhesive resin layer 15 and the sealant layer 16 may be laminated by a tandem lamination method or a coextrusion method in which the granules obtained by melt-blending in advance using a melt kneading device such as a single-screw extruder, a twin-screw extruder, or a Brabender mixer are extruded into the thermal adhesive resin layer 15 and the sealant layer 16 using an extrusion laminator. Alternatively, the thermal adhesive resin layer 15 and the sealant layer 16 may be laminated by a method in which the sealant layer is first formed as a cast film using the resin composition for forming a sealant layer, and then this sealant layer is sandwich-laminated with an adhesive resin. From the viewpoint of productivity, the formation speed (processing speed) of the thermal adhesive resin layer 15 and the sealant layer 16 can be, for example, 80 m / min or more.

[0091] (Aging treatment process) The aging treatment step is a step of aging (curing) the laminated structure. Aging the laminated structure can promote adhesion between the base layer 11, the first adhesive layer 12a, the first corrosion prevention treatment layer 14a, and the barrier layer 13, and between the barrier layer 13, the second corrosion prevention treatment layer 14b, the thermal adhesive resin layer 15, and the sealant layer 16. The aging temperature may be 80°C or higher, 100°C or higher, or 120°C or higher, and may be 140°C or lower, 150°C or lower, or 160°C or lower. The aging time may be 1 hour or longer, 2 hours or longer, or 3 hours or longer, and may be 24 hours or shorter, 48 hours or shorter, or 72 hours or shorter.

[0092] In this manner, an exterior packaging material 10 of one embodiment as shown in FIG. 1 can be manufactured.

[0093] The effects achieved by the packaging material 10 according to one embodiment will be described below with reference to FIGS. 3(a) and 3(b). FIG. 3(a) is a schematic cross-sectional view of a comparative packaging material pressed against a rigid body, and FIG. 3(b) is a schematic cross-sectional view of the packaging material for an electricity storage device according to one embodiment pressed against a rigid body. The comparative packaging material 100 shown in FIG. 3(a) differs from the packaging material 10 in that the ratio of the loop stiffness value of the laminate of the sealant layer 116 and the thermal adhesive resin layer 115 to the loop stiffness value of the base material layer 11 is less than 1 or greater than 15. Therefore, the loop stiffness value of the base material layer 11 and the loop stiffness value of the laminate are significantly different. Therefore, the stiffness of the laminate of the sealant layer 116 and the thermal adhesive resin layer 115, which is the innermost layer of the packaging material 100, is either too low (i.e., too soft) or too high (i.e., too hard) compared to the stiffness of the base material layer 11, which is the outermost layer of the packaging material 100.

[0094] When an exterior packaging material 100 including a laminate with too low stiffness is pressed against a rigid body 200, for example, the resin included in the sealant layer 116 easily flows. This resin flow causes the sealant layer 116 to deform, as shown in FIG. 3(a). This can cause significant variations in the thickness of the sealant layer 116, resulting in uneven application of pressure to the rigid body 200 via the exterior packaging material 100. Since this deformation is likely to occur in a high-temperature environment (e.g., 70°C or higher), uneven application of pressure tends to be more likely. On the other hand, when an exterior packaging material 100 including a laminate with too high stiffness is pressed against a rigid body 200, force tends to concentrate at a portion of the exterior packaging material 100 that contacts the end 200a (pressurized end, see FIG. 3(a)) of the rigid body 200. Alternatively, convex portions provided on the surface of the sealant layer 116 in accordance with the unevenness of the base material layer 11 are difficult to deform, and force tends to concentrate at these convex portions. Such a concentration of force tends to result in localized pressure being applied to the rigid body 200 via the exterior material 100. Therefore, not only when the stiffness is too low, but also when the stiffness is too high, the rigid body tends to be non-uniformly pressurized via the exterior material.

[0095] In contrast, in an exterior packaging material 10 according to one embodiment, where a laminate of the thermal adhesive resin layer 15 and the sealant layer 16 is designated as (I) and the base material layer 11 is designated as (II), the loop stiffness value of (I) is 10 mN or more and 80 mN or less, the loop stiffness value of (II) is 2 mN or more and 20 mN or less, the ratio of the loop stiffness values ​​of (I) and (II) (I / II) is 1.0 or more and 15 or less, and the thickness ratio of (I) to (II) (I / II) is 1.0 or more and 8.0 or less. This allows the stiffness of the innermost layer of the exterior packaging material 10, the stiffness of the outermost layer of the exterior packaging material 10, and the balance between these to be set within appropriate ranges. As a result, as shown in FIG. 3(b), even when pressure is applied to a rigid body 200 via the exterior packaging material 10 in a high-temperature environment, the exterior packaging material 10 is less likely to deform excessively. Therefore, even when pressure is applied to the rigid body 200 via the outer packaging material 10 in a high-temperature environment, pressure can be applied to the rigid body 200 uniformly via the outer packaging material 10.

[0096] The loop stiffness value of the resin layer (substrate layer 11, sealant layer 16, etc.) in the packaging material 10 can be adjusted by, for example, the layer thickness, the degree of crystallinity of the resin, the type of resin, etc. Generally, the loop stiffness value increases as the thickness of the resin layer increases. However, simply adjusting the loop stiffness value by adjusting the thickness of the resin layer may result in an excessively thick packaging material, which may result in insufficient durability of the packaging material. In contrast, in one embodiment, the thickness of the above-mentioned (I) is 30 μm or more and 120 μm or less, and the thickness of the above-mentioned (II) is 10 μm or more and 60 μm or less. In this case, the durability of the packaging material 10 can be ensured while keeping the thickness of the packaging material 10 low. Therefore, even when pressure is applied in a high-temperature environment, pinholes, breakage, etc., are unlikely to occur in the packaging material 10. In addition, the loop stiffness value of the above-mentioned (I) and the loop stiffness value of the above-mentioned (II) can be reliably set within the above-mentioned ranges.

[0097] In one embodiment, the ratio (I / II) of the loop stiffness values ​​of (I) and (II) may be 2.5 or more and 11.0 or less. In this case, the ratio (I / II) of the thicknesses of (I) and (II) may be 1.0 or more and 6.5 or less, the thickness of (I) may be 45 μm or more and 100 μm or less, and the thickness of (II) may be 15 μm or more and 50 μm or less. In this case, deformation of the packaging material 10 is well suppressed even when pressure is applied in a high-temperature environment.

[0098] In one embodiment, the ratio (I / II) of the loop stiffness values ​​of (I) and (II) may be 3.5 or more and 10.0 or less. In this case, the ratio (I / II) of the thicknesses of (I) and (II) may be 2.0 or more and 5.0 or less, the thickness of (I) may be 65 μm or more and 85 μm or less, and the thickness of (II) may be 20 μm or more and 40 μm or less. In this case, deformation of the packaging material 10 is more effectively suppressed even when pressure is applied in a high-temperature environment.

[0099] In one embodiment, the sealant layer 16 includes a polypropylene-based resin as a base resin, and the polypropylene-based resin may be composed of homopropylene or block polypropylene. In this case, melting of the sealant layer 16 in a high-temperature environment can be suppressed.

[0100] In one embodiment, the sealant layer 16 may further contain an additive resin containing a polyethylene-based resin or a block copolymer that is compatible with the polypropylene-based resin. In this case, deformation of the exterior packaging material 10 is further suppressed.

[0101] In one embodiment, the sealant layer 16 may further include an additive resin containing a polyethylene-based resin, and a compatibilizer having a portion compatible with the polypropylene-based resin and a portion compatible with the polyethylene-based resin, which can more effectively suppress deformation of the packaging material 10.

[0102] In one embodiment, the exterior material 10 may be an exterior material for an all-solid-state battery. In this case, even when the all-solid-state battery 50 is pressurized via the exterior material 10 in a high-temperature environment, the pressurization can be performed uniformly. This allows the output of the all-solid-state battery 50 to be improved satisfactorily. Therefore, the exterior material 10 can be highly suitable as an exterior material for the all-solid-state battery 50.

[0103] Hereinafter, an exterior packaging material according to a modified example of the above embodiment will be described with reference to Fig. 4. Note that in the modified example, explanations that overlap with the above embodiment will be omitted. Fig. 4 is a schematic cross-sectional view of an exterior packaging material for an electricity storage device according to the modified example. As shown in Fig. 4, exterior packaging material 20 is an exterior packaging material used in an electricity storage device, and includes a base material layer 11, a barrier layer 13, a second adhesive layer 12b, and a sealant layer 16, which are laminated in this order.

[0104] In the packaging material 20, the barrier layer 13 has a first corrosion prevention treatment layer 14a on the substrate layer 11 side via a first adhesive layer 12a, and has a second corrosion prevention treatment layer 14b on the sealant layer 16 side.

[0105] The exterior packaging material 20 differs from the exterior packaging material 10 in that a second adhesive layer 12b is used instead of the thermal adhesive resin layer 15. The thickness of the second adhesive layer 12b in the exterior packaging material 20 is significantly smaller than the thickness of the sealant layer 16, and therefore has almost no effect on the physical properties of the sealant layer 16. Therefore, in this modification, the sealant layer 16 is designated as (I) and the base material layer 11 is designated as (II). In this modification, the ratio of the thickness of (I) to the thickness of (II) and the ratio of the loop stiffness value of (I) to the loop stiffness value of (II) are each within the same range as in the above embodiment.

[0106] <Second adhesive layer> The second adhesive layer 12b will now be described. The second adhesive layer 12b is a layer that bonds the barrier layer 13 and the sealant layer 16. A general adhesive for bonding the barrier layer 13 and the sealant layer 16 can be used for the second adhesive layer 12b.

[0107] When a corrosion prevention treatment layer 14b is provided on the barrier layer 13 and the second corrosion prevention treatment layer 14b has a layer containing at least one polymer selected from the group consisting of the above-mentioned cationic polymers and anionic polymers, the second adhesive layer 12b is preferably a layer containing a compound (hereinafter also referred to as a "reactive compound") that is reactive with the above-mentioned polymer contained in the second corrosion prevention treatment layer 14b.

[0108] For example, when the second corrosion prevention treatment layer 14b contains a cationic polymer, the second adhesive layer 12b preferably contains a compound reactive with the cationic polymer. When the second corrosion prevention treatment layer 14b contains an anionic polymer, the second adhesive layer 12b preferably contains a compound reactive with the anionic polymer. When the second corrosion prevention treatment layer 14b contains both a cationic polymer and an anionic polymer, the second adhesive layer 12b preferably contains both a compound reactive with the cationic polymer and a compound reactive with the anionic polymer. However, the second adhesive layer 12b does not necessarily need to contain both of these compounds; it may contain a compound reactive with both the cationic polymer and the anionic polymer. Here, "reactive" means forming a covalent bond with the cationic polymer or the anionic polymer. The second adhesive layer 12b may also contain an acid-modified polyolefin resin.

[0109] The compound reactive with the cationic polymer may be at least one compound selected from the group consisting of a polyfunctional isocyanate compound, a glycidyl compound, a compound having a carboxy group, and a compound having an oxazoline group.

[0110] Examples of these polyfunctional isocyanate compounds, glycidyl compounds, compounds having a carboxy group, and compounds having an oxazoline group include the polyfunctional isocyanate compounds, glycidyl compounds, compounds having a carboxy group, and compounds having an oxazoline group exemplified above as crosslinking agents for forming a crosslinked structure from a cationic polymer. Among these, polyfunctional isocyanate compounds are preferred because they have high reactivity with cationic polymers and are easy to form a crosslinked structure.

[0111] The compound reactive with anionic polymers includes at least one compound selected from the group consisting of glycidyl compounds and compounds having an oxazoline group. These glycidyl compounds and compounds having an oxazoline group include the glycidyl compounds and compounds having an oxazoline group exemplified above as crosslinking agents for forming a crosslinked structure in cationic polymers. Among these, glycidyl compounds are preferred because of their high reactivity with anionic polymers.

[0112] When the second adhesive layer 12b contains an acid-modified polyolefin resin, the reactive compound preferably also has reactivity with the acidic groups in the acid-modified polyolefin resin (i.e., forms a covalent bond with the acidic groups). This further enhances adhesion to the second corrosion prevention treatment layer 14b. In addition, the acid-modified polyolefin resin forms a crosslinked structure, further improving the solvent resistance of the exterior material 20.

[0113] The content of the reactive compound is preferably from 1 to 10 times the equivalent of the acidic groups in the acid-modified polyolefin resin. If the amount is equal to or more than 10 times, the reactive compound will react sufficiently with the acidic groups in the acid-modified polyolefin resin. On the other hand, if the amount exceeds 10 times, the crosslinking reaction with the acid-modified polyolefin resin will be fully saturated, resulting in the presence of unreacted material and concerns about a decrease in various performances. Therefore, for example, the content of the reactive compound is preferably 5 to 20 parts by mass (solid content ratio) per 100 parts by mass of the acid-modified polyolefin resin.

[0114] The acid-modified polyolefin resin is a polyolefin resin into which an acidic group has been introduced. Examples of the acidic group include a carboxyl group, a sulfonic acid group, and an acid anhydride group, with a maleic anhydride group and a (meth)acrylic acid group being particularly preferred. For example, the acid-modified polyolefin resin may be the same as the modified polyolefin resin used in the sealant layer 16.

[0115] The second adhesive layer 12b may contain various additives such as a flame retardant, a slip agent, an antiblocking agent, an antioxidant, a light stabilizer, and a tackifier.

[0116] The second adhesive layer 12b may contain, for example, an acid-modified polyolefin and at least one curing agent selected from the group consisting of a polyfunctional isocyanate compound, a glycidyl compound, a compound having a carboxy group, a compound having an oxazoline group, and a carbodiimide compound, from the viewpoint of suppressing a decrease in heat seal strength when corrosive gases such as hydrogen sulfide or an electrolyte are involved and further suppressing a decrease in insulating properties. Examples of the carbodiimide compound include N,N'-di-o-toluylcarbodiimide, N,N'-diphenylcarbodiimide, N,N'-di-2,6-dimethylphenylcarbodiimide, N,N'-bis(2,6-diisopropylphenyl)carbodiimide, N,N'-dioctyldecylcarbodiimide, N-triyl-N'-cyclohexylcarbodiimide, N,N'-di-2,2-di-t-butylphenylcarbodiimide, N-triyl-N'-phenylcarbodiimide, N,N'-di-p-nitrophenylcarbodiimide, N,N'-di-p-aminophenylcarbodiimide, N,N'-di-p-hydroxyphenylcarbodiimide, N,N'-di-cyclohexylcarbodiimide, and N,N'-di-p-toluylcarbodiimide.

[0117] The adhesive for forming the second adhesive layer 12b may be, for example, a polyurethane adhesive containing a polyester polyol made of a hydrogenated dimer fatty acid and a diol, and a polyisocyanate. Examples of adhesives include polyurethane resins in which a bifunctional or higher isocyanate compound is reacted with a base material such as polyester polyol, polyether polyol, acrylic polyol, or carbonate polyol, and epoxy resins in which an amine compound or the like is reacted with a base material having an epoxy group. These are preferred from the standpoint of heat resistance.

[0118] The thickness of the second adhesive layer 12b is not particularly limited, but from the viewpoint of obtaining the desired adhesive strength and processability, it is preferably 1 μm or more and 10 μm or less, and more preferably 2 μm or more and 7 μm or less.

[0119] Next, a description will be given of an example of a method for manufacturing the exterior packaging material 20 shown in Fig. 4. Note that the method for manufacturing the exterior packaging material 20 is not limited to the following method.

[0120] The manufacturing method of the exterior packaging material 20 according to the modified example is generally configured to include the steps of providing corrosion prevention treatment layers 14a, 14b on the barrier layer 13, bonding the base material layer 11 and the barrier layer 13 together using a first adhesive layer 12a, bonding the sealant layer 16 to the corrosion prevention treatment layer 14b side of the barrier layer 13 via a second adhesive layer 12b to obtain a laminated structure, and, if necessary, aging the obtained laminated structure. The steps up to the step of bonding the base material layer 11 and the barrier layer 13 together using the first adhesive layer 12a can be performed in the same manner as the manufacturing method of the exterior packaging material 10 described above. The step of aging the obtained laminated structure can be performed in the same manner as the manufacturing method of the exterior packaging material 10 described above.

[0121] (Laminating step of second adhesive layer and sealant layer) The lamination step of the second adhesive layer and sealant layer is a step of obtaining a laminated structure by laminating the sealant layer 16 via the second adhesive layer 12b to the corrosion prevention treatment layer 14b side of the barrier layer 13. Examples of lamination methods include a wet process and dry lamination.

[0122] In the case of a wet process, a solution or dispersion of the adhesive constituting the second adhesive layer 12b is applied onto the corrosion prevention treatment layer 14b, and the solvent is evaporated at a predetermined temperature to form a dry film, or a baking process is performed as necessary after the dry film formation. Then, the sealant layer 16 is laminated to produce the exterior material 20. Examples of application methods include the various application methods exemplified above. The preferred dry application amount of the second adhesive layer 12b is the same as that of the first adhesive layer 12a.

[0123] In this case, the sealant layer 16 can be produced, for example, by a melt extrusion molding machine using a resin composition for forming a sealant layer containing the above-mentioned base resin, additive resin, and compatibilizer. From the viewpoint of productivity, the melt extrusion molding machine can be processed at a processing speed of 80 m / min or more.

[0124] The exterior packaging material 20 according to the modified example described above also exhibits the same effects as those of the above embodiment.

[0125] An exterior packaging material for an electricity storage device according to one aspect of the present disclosure is as described in the following [1] to [9], and has been described in detail based on the above embodiment and the above modified example. [1] An exterior packaging material for an electricity storage device, comprising a base material layer, a barrier layer, a thermal adhesive resin layer or adhesive layer, and a sealant layer laminated in this order, wherein, when the thermal adhesive resin layer and the sealant layer, or the sealant layer, are (I) and the base material layer is (II), the loop stiffness value of (I) is 10 mN or more and 80 mN or less, the loop stiffness value of (II) is 2 mN or more and 20 mN or less, the ratio of the loop stiffness values ​​of (I) and (II) (I / II) is 1.0 or more and 15 or less, and the thickness ratio of (I) to (II) (I / II) is 1.0 or more and 8.0 or less. [2] The packaging material for an electricity storage device according to [1], wherein the thickness of (I) is 30 μm or more and 120 μm or less, and the thickness of (II) is 10 μm or more and 60 μm or less. [3] The packaging material for an electricity storage device according to [1] or [2], wherein the ratio (I / II) of the loop stiffness values ​​of (I) and (II) is 2.5 or more and 11.0 or less. [4] The packaging material for an electricity storage device according to any one of [1] to [3], wherein the ratio (I / II) of the loop stiffness values ​​of (I) and (II) is 3.5 or more and 10 or less. [5] The packaging material for an electricity storage device according to any one of [1] to [4], wherein the sealant layer contains a polypropylene-based resin as a base resin, and the polypropylene-based resin is composed of homopropylene or block polypropylene. [6] The packaging material for an electricity storage device according to [5], wherein the sealant layer further contains an additive resin containing a polyethylene-based resin, or a block copolymer that is compatible with the polypropylene-based resin. [7] The exterior packaging material for an electricity storage device according to [5], wherein the sealant layer further contains an additive resin containing a polyethylene-based resin, and a compatibilizer having a portion compatible with the polypropylene-based resin and a portion compatible with the polyethylene-based resin. [8] The packaging material for an electricity storage device according to [7], wherein the compatibilizer contains a block copolymer of polypropylene and polyethylene, or a block copolymer of polyethylene and polyethylenebutylene. [9] The packaging material for an electricity storage device according to any one of [1] to [8], which is a packaging material for an all-solid-state battery.

[0126] However, one aspect of the present disclosure is not limited to the above embodiment, the above modification, and the above [1] to [9]. One aspect of the present disclosure can be further modified within the scope of the gist thereof. For example, in the above embodiment and modification, a corrosion prevention treatment layer is provided on each of both sides of the barrier layer, but this is not limited thereto. The exterior material may have only one corrosion prevention treatment layer, or may not have any corrosion prevention treatment layer.

[0127] The electrical storage device packaging material of the present disclosure can be used as a packaging material for electrical storage devices such as secondary batteries, such as lithium-ion batteries, nickel-metal hydride batteries, and lead-acid batteries, as well as electrochemical capacitors, such as electric double-layer capacitors. However, the electrical storage device packaging material of the present disclosure is particularly suitable for use as a packaging material for an electrical storage device consisting of an all-solid-state battery. The electrical storage device packaging material has an adjusted loop stiffness ratio between the thermal adhesive resin layer and the sealant layer, or between the sealant layer and the substrate layer, provided in the packaging material. Therefore, when the electrical storage device packaging material is used as a packaging material for an all-solid-state battery including an electrical storage element and the electrical storage element is pressurized via the packaging material, not only is the packaging material less susceptible to deformation by heat and pressure, but the presence of areas of high and low pressure on the pressurized surface of the electrical storage element is suppressed, resulting in uniform pressure being applied to the pressurized surface of the electrical storage element. As a result, the all-solid-state battery can be operated efficiently. [Example]

[0128] The present disclosure will be described in more detail below based on examples, but the present disclosure is not limited to the following examples.

[0129] [Materials used] The materials used as the barrier layer, the thermal adhesive resin layer, the first adhesive layer, the second adhesive layer, the material for forming the first corrosion prevention treatment layer, and the material for forming the second corrosion prevention treatment layer are as follows.

[0130] <Barrier layer (thickness 40 μm)> Annealed and degreased soft aluminum foil (manufactured by Toyo Aluminum, "8079 material")

[0131] <Resin composition for forming a thermal adhesive resin layer> A resin composition for forming a thermal adhesive resin layer, which is a dry blend of maleic anhydride-modified homopolypropylene and a polyethylene-based elastomer.

[0132] <First adhesive layer (mass per unit area 4.0 g / m2 ) to form the first adhesive> An adhesive (first adhesive) was prepared by blending polyester polyol (manufactured by Showa Denko Materials Co., Ltd., product name: Teslac 2505-63, hydroxyl value: 7 to 11 mgKOH / g) and nurate form of isophorone diisocyanate (manufactured by Mitsui Chemicals, Inc., product name: Takenate 600) so that the NCO / OH ratio was 20.0, and diluting the mixture with ethyl acetate to a solids content of 26% by mass.

[0133] <Second adhesive layer (mass per unit area 3.0 g / m 2 ) to form a second adhesive An adhesive (second adhesive) made by blending 100 parts by mass of acid-modified polyolefin resin dissolved in toluene with 10 parts by mass (solid content ratio) of a polyisocyanate compound with an isocyanurate structure.

[0134] <Material for forming first corrosion prevention treatment layer and material for forming second corrosion prevention treatment layer> The first corrosion prevention treatment layer forming material (substrate layer side) and the second corrosion prevention treatment layer forming material (sealant layer side) are as shown below in (CL-1) and (CL-2). (CL-1): Sodium polyphosphate-stabilized cerium oxide sol adjusted to a solids concentration of 10% by mass using distilled water as a solvent. (CL-2): A composition prepared by using distilled water as a solvent and adjusting the solid content concentration to 5% by mass.

[0135] The sodium polyphosphate-stabilized cerium oxide sol was prepared by blending 100 parts by mass of cerium oxide with 10 parts by mass of sodium phosphate. The mass ratio of polyallylamine (manufactured by Nitto Boseki Co., Ltd.) to polyglycerol polyglycidyl ether (manufactured by Nagase ChemteX Corporation) in the composition was 90:10.

[0136] <Sealant layer> The base resin, additive resin, and compatibilizer used in the sealant layer are as shown in Table 1. In Table 1, "PP" stands for "polypropylene" and "PE" stands for "polyethylene."

[0137] [Table 1]

[0138] The substrate layer used was the following (D1) or (D2). (D1): Polyethylene terephthalate film with corona treatment on one side (D2): Nylon film

[0139] [Fabrication of exterior materials] Example 1 First, a first and second corrosion prevention treatment layer were provided on the barrier layer. Specifically, (CL-1) was applied to both surfaces of the barrier layer in a dry coating amount of 70 mg / m 2 The resulting layer was coated by microgravure coating so that the coating amount was 20 mg / m, and then baked in a drying unit at 200°C. 2 By applying the coating by microgravure coating so that the coating was as follows, a composite layer consisting of (CL-1) and (CL-2) was formed as the first and second corrosion prevention treatment layers. This composite layer exhibits corrosion prevention performance by combining the two types of (CL-1) and (CL-2).

[0140] Next, the first corrosion prevention treatment layer side of the barrier layer provided with the first and second corrosion prevention treatment layers was attached to the substrate layer by dry lamination using a first adhesive to form a first adhesive layer, thereby obtaining a first laminate (substrate layer / first adhesive layer / first corrosion prevention treatment layer / barrier layer / second corrosion prevention treatment layer). Specifically, the first adhesive was applied to the surface of the barrier layer facing the first corrosion prevention treatment layer so that the thickness after curing was 4 μm, dried at 80°C for 1 minute, and then laminated to the substrate layer. The laminate was then aged at 80°C for 120 hours to obtain a first laminate. The substrate layers used here were those shown in Table 2.

[0141] The first laminate was then placed on the unwinding section of an extrusion laminator. A thermal adhesive resin layer and a sealant layer were laminated in this order onto the second corrosion prevention treatment layer of the first laminate by co-extrusion through a T-die at 270°C and 80 m / min, yielding an exterior material (a laminate of substrate layer / first adhesive layer / first corrosion prevention treatment layer / barrier layer / second corrosion prevention treatment layer / thermal adhesive resin layer / sealant layer). The thicknesses of the thermal adhesive resin layer and the sealant layer were 25 μm and 55 μm, respectively. For the sealant layer, a resin composition for forming a sealant layer was prepared in advance by dry-blending the base resin, additive resin, and compatibilizer shown in Table 2 to have the content shown in Table 2. This resin composition was used. For the thermal adhesive resin layer, a resin composition for forming a thermal adhesive resin layer was prepared in advance and used.

[0142] Examples 2 to 8 Except for the composition of the sealant layer shown in Table 2, the same procedure as in Example 1 was followed to prepare exterior packaging materials.

[0143] Example 9 An exterior packaging material was produced in the same manner as in Example 1, except that the thickness of the substrate layer was changed to 35 μm.

[0144] Example 10 A first laminate (substrate layer / first adhesive layer / first corrosion prevention treatment layer / barrier layer / second corrosion prevention treatment layer) was obtained in the same manner as in Example 1. A sealant layer was formed under the same processing conditions as in Example 1. Next, a sealant layer shown in Table 2 was attached to the second corrosion prevention treatment layer of the first laminate by dry lamination using a second adhesive for forming the second adhesive layer. The first laminate and the sealant layer were laminated by applying the second adhesive to the second corrosion prevention treatment layer to a thickness of 3 μm after drying, drying at 80°C for 1 minute, laminating with the sealant layer, and aging at 120°C for 3 hours. In this way, an exterior material (a laminate of substrate layer / first adhesive layer / first corrosion prevention treatment layer / barrier layer / second corrosion prevention treatment layer / second adhesive layer / sealant layer) was produced.

[0145] (Comparative Example 1) Except for using the materials for the base layer and the compositions for the sealant layer as shown in Table 2, exterior packaging materials were produced in the same manner as in Example 1.

[0146] (Comparative Example 2) Except for using the materials for the base material layer as shown in Table 2, exterior materials were produced using the dry lamination method in the same manner as in Example 10.

[0147] (Comparative Example 3) Except for using the composition of the sealant layer as shown in Table 2, the same procedure as in Example 9 was carried out to prepare an exterior packaging material.

[0148] Comparative Example 4 An exterior material was produced in the same manner as in Example 1, except that the thicknesses of the thermal adhesive resin layer and the sealant layer were changed to 5 μm and 15 μm, respectively.

[0149] <Loop stiffness value> The loop stiffness value was measured using a loop stiffness tester DA-S manufactured by Toyo Seiki Seisakusho, Ltd. The loop stiffness value was specifically measured as follows. First, a test film with a width direction (TD) of 15 mm and a machine direction (MD) of 200 mm was prepared. Next, both ends of the test film were fixed with chucks to form a loop with a loop length of 85 mm. This loop was compressed with an indenter at a compression speed of 3.3 mm / min, a compression time of 3 seconds, and a compression distance of 20 mm, and the load of the indenter was measured. The maximum load measured in this test was used as the loop stiffness value. The compression distance refers to the distance when the indenter and the chuck were closest to each other. Table 2 shows the measurement results of the loop stiffness values ​​of the thermal adhesive resin layer and the sealant layer in Examples 1 to 9 and Comparative Examples 1 and 3 to 4, the measurement results of the loop stiffness value of the sealant layer in Example 10 and Comparative Example 2, and the measurement results of the loop stiffness value of the base layer in Examples 1 to 10 and Comparative Examples 1 to 4.

[0150] <Deformation rate of exterior materials> The deformation rate was evaluated for the exterior packaging materials obtained in Examples 1 to 10 and Comparative Examples 1 to 4. Specifically, first, the exterior packaging material was placed on a SUS plate. At this time, the exterior packaging material was placed so that the sealant layer was in contact with the SUS plate. Next, a SUS block having a bottom surface with short sides of 10 mm and long sides of 40 mm was placed on the exterior packaging material. At this time, the SUS block was placed so that the base layer was in contact with the bottom surface of the SUS block. Note that the SUS plate and the SUS block can each be heated using a heater. Next, while the SUS plate and the SUS block were each maintained at 100°C, the SUS block pressed the exterior packaging material with a force of 5 MPa for 1 hour along the stacking direction of the SUS plate, exterior packaging material, and SUS block. Thereafter, the pressed exterior packaging material was solidified using an epoxy resin, and a cross-section was exposed using a polishing machine, and the cross-section of the exterior packaging material was observed using a microscope. The thickness (X) of the thermal adhesive resin layer and sealant layer of the packaging materials in Examples 1 to 9 and Comparative Examples 1, 3 and 4, or the sealant layer of the packaging material in Example 10 and Comparative Example 2, was measured at the location where the thickness change was greatest. The deformation rate ((XY) / Y×100) was calculated from the thickness (Y) of the thermal adhesive resin layer and sealant layer of the packaging materials in Examples 1 to 9 and Comparative Examples 1, 3 and 4, or the sealant layer of the packaging material in Example 10 and Comparative Example 2, before heating and pressure application. The deformation rate was evaluated based on the following evaluation criteria. The evaluation results are shown in Table 2. [Evaluation criteria] A: When the deformation rate is less than 5% B: When the deformation rate is 5% or more but less than 10% C: When the deformation rate is 10% or more but less than 15% D: When the deformation rate is 15% or more

[0151] [Table 2] [Explanation of symbols]

[0152] 10, 20, 100...outer packaging material (outer packaging material for electricity storage device), 11...base material layer, 12a...first adhesive layer, 12b...second adhesive layer (adhesive layer), 13...barrier layer, 14a...first corrosion prevention treatment layer, 14b...second corrosion prevention treatment layer, 15, 115...thermal adhesive resin layer, 16, 116...sealant layer, 50...all-solid-state battery (electricity storage device), 52...electricity storage element, 54...outer packaging bag, 54a...bag body, 54b...sealing portion.

Claims

1. The laminated sheet has a base layer, a barrier layer, a thermal adhesive resin layer or an adhesive layer, and a sealant layer, which are laminated in this order; When the thermal adhesive resin layer and the sealant layer, or the sealant layer, are defined as (I) and the base material layer is defined as (II), The loop stiffness value of (I) is 10 mN or more and 80 mN or less, The loop stiffness value of (II) is 2 mN or more and 20 mN or less, the ratio (I / II) of the loop stiffness values ​​of (I) and (II) is 2.5 or more and 11 or less, The ratio (I / II) of the thickness of the (I) to the thickness of the (II) is 1.0 or more and 8.0 or less. Exterior material for energy storage devices.

2. The thickness of the (I) is 30 μm or more and 120 μm or less, The packaging material for an electricity storage device according to claim 1, wherein the thickness of (II) is 10 μm or more and 60 μm or less.

3. 2. The packaging material for an electricity storage device according to claim 1, wherein a ratio (I / II) of loop stiffness values ​​of said (I) and said (II) is 3.5 or more and 10 or less.

4. the sealant layer contains a polypropylene-based resin as a base resin, The packaging material for an electricity storage device according to claim 1 , wherein the polypropylene-based resin is composed of homopropylene or block polypropylene.

5. The packaging material for an electricity storage device according to claim 4 , wherein the sealant layer further contains an additive resin containing a polyethylene-based resin, or a block copolymer that is compatible with the polypropylene-based resin.

6. 5. The exterior packaging material for an electricity storage device according to claim 4, wherein the sealant layer further comprises an additive resin containing a polyethylene-based resin, and a compatibilizer having a portion compatible with the polypropylene-based resin and a portion compatible with the polyethylene-based resin.

7. The packaging material for an electricity storage device according to claim 6 , wherein the compatibilizer comprises a block copolymer of polypropylene and polyethylene, or a block copolymer of polyethylene and polyethylenebutylene.

8. The electrical storage device packaging material according to any one of claims 1 to 7, which is an packaging material for an all-solid-state battery.

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