Exterior material for energy storage devices and energy storage devices using the same

Abstract

To provide an exterior material for a power storage device having excellent scratch resistance, and a power storage device using the same.SOLUTION: An exterior material for a power storage device includes at least a substrate layer, a barrier layer, and a sealant layer in this order. The sealant layer includes a polypropylene-based resin (A) and an incompatible component (B) that is incompatible relative to the polypropylene-based resins. When a cross section of the sealant layer along a TD direction is observed, an areal ratio S1 of the incompatible components (B) in a cross section is 10 to 50%.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This disclosure relates to an exterior material for energy storage devices and an energy storage device using the same. [Background technology]

[0002] As energy storage devices, 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, are well known. Due to the miniaturization of portable devices and limitations on installation space, there is a demand for further miniaturization of energy storage devices, and lithium-ion batteries, which have high energy density, are attracting attention. Conventionally, metal cans were used as the outer casing material for lithium-ion batteries, but now multilayer films that are lightweight, have high heat dissipation, and can be manufactured at low cost are being used.

[0003] Lithium-ion batteries that use the above-mentioned multilayer film as an outer casing are called laminate-type lithium-ion batteries. The outer casing covers the battery contents (positive electrode, separator, negative electrode, electrolyte, etc.) and prevents moisture from entering the interior. Laminate-type lithium-ion batteries are manufactured, for example, by forming a recess in a part of the outer casing by cold molding, housing the battery contents in the recess, folding back the remaining part of the outer casing, and sealing the edges with heat seal (see, for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2013-101765 [Overview of the project] [Problems that the invention aims to solve]

[0005] Incidentally, research and development is underway on a next-generation energy storage device called a solid-state battery, which is being developed as a successor to lithium-ion batteries. Solid-state batteries operate under pressure to increase the conductivity of the battery elements. In order to operate the battery efficiently, it is necessary to apply uniform pressure to the battery elements.

[0006] On the other hand, during the battery manufacturing process, the sealant layer can be damaged when the outer packaging material is transported on rolls. If the sealant layer is damaged, the pressure on the battery elements will not be uniform, and the battery's operating efficiency will decrease. In other words, the outer packaging material needs to have excellent scratch resistance.

[0007] This disclosure provides an exterior material for energy storage devices that has excellent scratch resistance, and an energy storage device using the same. [Means for solving the problem]

[0008] One aspect of this disclosure provides an exterior material for an energy storage device, comprising at least a base layer, a barrier layer, and a sealant layer in that order, wherein the sealant layer contains a polypropylene resin (A) and an incompatible component (B) that is incompatible with the polypropylene resin, and when the cross-section of the sealant layer along the TD direction is observed, the area ratio S1 of the incompatible component (B) in the cross-section is 10 to 50%.

[0009] The above-mentioned exterior material exhibits excellent scratch resistance. The inventors surmise the reason for this effect as follows: The sealant layer of the above-mentioned exterior material contains a polypropylene resin (A) and an incompatible component (B). As a result, the incompatible component (B) plays a role in relieving the stress applied to the exterior material. In order to relieve stress and ensure scratch resistance, an appropriate distribution of stress is necessary. When the area ratio S1 is 10% or more, the stress relief by the incompatible component (B) is sufficient, and the occurrence of scratches in the sealant layer is suppressed. Furthermore, when the area ratio S1 is 50% or less, the stress applied to the exterior material is prevented from bouncing back and damaging the sealant layer. As a result, the exterior material exhibits excellent scratch resistance.

[0010] Generally, one way to improve scratch resistance is to incorporate a nucleating agent into the sealant layer to harden it. However, this reduces the seal strength. The above-mentioned exterior material exhibits excellent scratch resistance even when the sealant layer does not contain a nucleating agent.

[0011] When observing a cross-section of the sealant layer along the MD direction, the area ratio S2 of the incompatible component (B) in the cross-section may be between 10% and 40%. An area ratio S2 of 10% or more allows for more sufficient stress relaxation by the incompatible component (B). Furthermore, an area ratio S2 of 40% or less further suppresses the rebound of stress applied to the exterior material, which damages the sealant layer. As a result, the exterior material tends to exhibit superior scratch resistance.

[0012] In one embodiment, the ratio S1 / S2 of the area ratio S1 to the area ratio S2 may be greater than 1. Scratches in the sealant layer of the exterior material are caused by stress applied from the rolls during roll transport, and this stress is applied in the TD direction. When S1 / S2 is greater than 1, the stress is relieved more efficiently. As a result, the exterior material tends to have even better scratch resistance.

[0013] In one embodiment, the exterior material further comprises an adhesive resin layer between the barrier layer and the sealant layer, wherein the adhesive resin layer contains a polypropylene resin (A) and an incompatible component (B) that is incompatible with the polypropylene resin, and when a cross-section of the adhesive resin layer along the TD direction is observed, the area ratio S3 of the incompatible component (B) in the cross-section may be 20-70%. By including both the polypropylene resin (A) and the incompatible component (B) in the adhesive resin layer, the incompatible component (B) plays a role in relieving the stress applied to the exterior material. When the area ratio S3 is 20% or more, the stress relief by the incompatible component (B) is sufficient. Furthermore, when the area ratio S3 is 70% or less, the rebound of stress applied to the exterior material and damage to the sealant layer is suppressed. As a result, the exterior material tends to have even better scratch resistance.

[0014] In one aspect, when observing a cross-section along the MD direction of the adhesive resin layer, the area ratio S4 of the incompatible component (B) occupying the cross-section may be 20 to 60%. When the area ratio S4 is 20% or more, the stress relaxation by the incompatible component (B) becomes more sufficient. Further, when the area ratio S4 is 60% or less, the stress applied to the exterior material is further suppressed from damaging the bounce-back sealant layer. As a result, the exterior material tends to be more excellent in scratch resistance.

[0015] In one aspect, the ratio S3 / S4 of the area ratio S3 to the area ratio S4 may be greater than 1. The scratch on the sealant layer of the exterior material is caused by the stress applied from the roll during roll conveyance, and the stress is applied in the TD direction. When S3 / S4 is greater than 1, the stress is relaxed more efficiently. As a result, the exterior material tends to be more excellent in scratch resistance.

[0016] In one aspect, the ratio S3 / S1 of the area ratio S3 to the area ratio S1 may be greater than 1. Since S3 / S1 is greater than 1, the incompatible component (B) (island component) becomes more in the interior (adhesive resin) than the stress origin (sealant side). Thereby, the stress is further relaxed and the bounce-back of the stress becomes less. Therefore, the above exterior material tends to be more excellent in scratch resistance.

[0017] In one aspect, the sealant layer may be thicker than the adhesive resin layer. Thereby, the exterior material becomes more likely to disperse stress, and the above exterior material tends to be more excellent in scratch resistance. In one aspect, the incompatible component (B) may contain a polyethylene-based component. Thereby, the above exterior material tends to be more excellent in scratch resistance. In one aspect, the above exterior material may be for an all-solid-state battery.

[0018] Another aspect of the present disclosure may be a power storage device including a power storage device main body and the above exterior material that houses the power storage device main body. In one aspect, the above power storage device may be an all-solid-state battery.

Advantages of the Invention

[0019] According to the present disclosure, there are provided an exterior material for a power storage device having excellent scratch resistance and a power storage device using the same.

Brief Description of the Drawings

[0020] [Figure 1] FIG. 1 is a schematic cross-sectional view of an exterior material according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a schematic cross-sectional view along the TD direction of the sealant layer of the exterior material according to an embodiment of the present disclosure. [Figure 3] FIG. 3 is a schematic cross-sectional view along the MD direction of the sealant layer of the exterior material according to an embodiment of the present disclosure. [Figure 4] FIG. 4 is a schematic cross-sectional view of an exterior material according to an embodiment of the present disclosure. [Figure 5] FIG. 5 is a perspective view of a power storage device according to an embodiment of the present disclosure.

Embodiments for Carrying Out the Invention

[0021] Hereinafter, preferred embodiments of the present disclosure will be described in detail with appropriate reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and overlapping descriptions are omitted. Also, the dimensional ratios in the drawings are not limited to the illustrated ratios.

[0022] [Exterior Material for Power Storage Device] Figure 1 is a schematic cross-sectional view showing one embodiment of the exterior material for an energy storage device according to the present disclosure. As shown in Figure 1, the exterior material (exterior material for an energy storage device) 10 of this embodiment is a laminate in which a base layer 11, a first adhesive layer 12a disposed on one side of the base layer 11, a barrier layer 13 disposed on the opposite side of the first adhesive layer 12a from the base layer 11 and having corrosion-preventive treatment layers (first corrosion-preventive treatment layer 14a and second corrosion-preventive treatment layer 14b) on both sides, an adhesive resin layer 15 disposed on the opposite side of the barrier layer 13 from the first adhesive layer 12a, and a sealant layer 16 disposed on the opposite side of the adhesive resin layer 15 from the barrier layer 13 are laminated. Here, the first corrosion-preventive treatment layer 14a is provided on the side of the barrier layer 13 facing the base layer 11, and the second corrosion-preventive treatment layer 14b is provided on the side of the barrier layer 13 facing the sealant layer 16. In the exterior material 10, the base layer 11 is the outermost layer, and the sealant layer 16 is the innermost layer. That is, the exterior material 10 is used with the base layer 11 facing the outside of the energy storage device and the sealant layer 16 facing the inside of the energy storage device.

[0023] The following will provide a detailed explanation of each layer that makes up the exterior material 10.

[0024] <Base material layer 11> The base layer 11 provides heat resistance during the sealing process when manufacturing energy storage devices and plays a role in suppressing the occurrence of pinholes that may occur during molding and distribution. In particular, for exterior materials of large-scale energy storage devices, it can also provide scratch resistance, chemical resistance, and insulation.

[0025] The base layer 11 is preferably a layer formed of an insulating resin. Suitable resins include polyester resin, polyamide resin, polyimide resin, polyamide-imide resin, polyetherketone resin, polyphenylene sulfide resin, polyetherimide resin, polysulfone resin, fluororesin, phenolic resin, melamine resin, urethane resin, allyl resin, silicone resin, epoxy resin, furan resin, acetylcellulose resin, and the like.

[0026] These resins, when applied to the substrate layer 11, may be in the form of stretched or unstretched films, or as coating films. Furthermore, the substrate layer 11 may be single-layer or multi-layer, and in the case of multi-layer, different resins can be used in combination. If it is a film, it can be co-extruded or laminated with an adhesive. In the case of a coating film, it can be coated multiple times, and a multi-layer structure can be created by combining film and coating films.

[0027] Among these resins, polyester resins and polyamide resins are preferred as materials for constituting the base layer 11 due to 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, copolymers of nylon 6 and nylon 6,6, nylon 6, nylon 9T, nylon 10, polymetaxylylene adipamide (MXD6), nylon 11, nylon 12, etc.

[0028] When these resins are used in film form, a biaxially oriented film is preferred. Examples of stretching methods for biaxially oriented films include sequential biaxial stretching, tubular biaxial stretching, and simultaneous biaxial stretching. From the viewpoint of obtaining better deep-drawing moldability, a biaxially oriented film is preferably stretched by tubular biaxial stretching.

[0029] The thickness of the base layer 11 is preferably 6 to 100 μm, more preferably 10 to 75 μm, and even more preferably 10 to 50 μm. A base layer thickness of 6 μm or more tends to improve the pinhole resistance and insulation properties of the exterior material 10. A base layer thickness of 50 μm or less tends to reduce the total thickness of the exterior material 10.

[0030] Furthermore, it is preferable that the base layer 11 has a melting peak temperature higher than the melting peak temperature of the sealant layer 16. If the sealant layer 16 has a multilayer structure, the melting peak temperature of the sealant layer 16 refers to the melting peak temperature of the layer with the highest melting peak temperature. By having the base layer 11 have a melting peak temperature higher than the melting peak temperature of the sealant layer 16, it is possible to suppress deterioration of the appearance caused by the melting of the base layer 11 (outer layer) during heat sealing.

[0031] The melting peak temperature of the base layer 11 is preferably 290°C or higher, and more preferably 290 to 350°C. Examples of resin films that can be used as the base layer 11 and have a melting peak temperature within the above range include nylon film, polyester film such as PET film, polyamide film, and polyphenylene sulfide film (PPS film). A commercially available film may be used as the base layer 11, or the base layer 11 may be formed by coating (application and drying of a coating liquid). The base layer 11 may be a single-layer structure or a multi-layer structure, and may be formed by coating with a thermosetting resin. Furthermore, the base layer 11 may contain various additives (e.g., flame retardants, slip agents, antiblocking agents, antioxidants, light stabilizers, tackifiers, etc.).

[0032] Melting peak temperature T of substrate layer 11 11 and the melting peak temperature T of the sealant layer 16 16 The difference (T 11 -T 16 The temperature is preferably 20°C or higher. This temperature difference of 20°C or higher further effectively suppresses deterioration of the appearance of the exterior material 10 caused by heat sealing.

[0033] <First adhesive layer 12a> The first adhesive layer 12a is a layer that adheres the substrate layer 11 and the barrier layer 13. Specifically, the materials constituting the first adhesive layer 12a include, for example, polyurethane resins obtained by reacting a bifunctional or more isocyanate compound (polyfunctional isocyanate compound) with a main component such as polyester polyol, polyether polyol, acrylic polyol, or carbonate polyol. The various polyols mentioned above can be used alone or in combination of two or more, depending on the functions and performance required of the exterior material 10. In addition, epoxy resins with a curing agent can also be used, but are not limited to these.

[0034] The first adhesive layer 12a is formed using an adhesive composition containing the main agent and curing agent described above. Depending on the performance required for the adhesive layer, other various additives and stabilizers may be added to the adhesive composition described above.

[0035] 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 aromatic rings in their molecular structure. Examples of polyfunctional isocyanate compounds include the nurate form of isophorone diisocyanate, the adduct form of tolylene diisocyanate, the adduct form of hexamethylene diisocyanate, the biuret and nurate forms of hexamethylene diisocyanate, the biuret and nurate forms of tolylene diisocyanate, the adduct form of diphenylmethane diisocyanate, the biuret and nurate forms of xylylene diisocyanate.

[0036] As a curing agent, an alicyclic isocyanate polymer and an isocyanate polymer containing an aromatic ring in its molecular structure may be used in combination. Using these in combination tends to further improve heat resistance.

[0037] From the viewpoint of further improving heat resistance, the adhesive composition preferably contains at least one polyol selected from the group consisting of polyester polyols, acrylic polyols, and polycarbonate diols. Among these, polyester polyols are more preferred from the viewpoint of further improving heat resistance.

[0038] In adhesive compositions, the ratio of isocyanate groups in a polyfunctional isocyanate compound to the number of hydroxyl groups in a polyol (NCO / OH) may be 1.5 to 40.0 or 15.0 to 30.0. When this ratio is 1.5 or higher, the curing agents react with each other, and by-products such as urea resin and biuret resin are easily formed. Since these by-products contain active hydrogen groups, they interact with the polar groups of adjacent layers, improving interfacial adhesion and thus tending to improve heat resistance. On the other hand, when the above ratio is 40.0 or lower, the laminate strength at room temperature and high temperature environments can be further improved.

[0039] The thickness of the first adhesive layer 12a is not particularly limited, but from the viewpoint of obtaining desired adhesive strength, conformability, and processability, for example, 1 to 10 μm is preferred, and 2 to 7 μm is more preferred.

[0040] The mass per unit area of ​​the first adhesive layer 12a is set to 2.0 to 6.0 g / m², from the viewpoint of ensuring superior laminate strength in both room temperature and high temperature environments, as well as obtaining superior deep-draw moldability. 2 It may also be 2.5-5.0 g / m 2 It may also be 3.0-4.0 g / m 2 That's fine.

[0041] <Barrier layer 13> The barrier layer 13 has water vapor barrier properties that prevent moisture from entering the interior of the energy storage device. The barrier layer 13 may also have ductility for deep drawing. As the barrier layer 13, for example, various metal foils such as aluminum, stainless steel, and copper, or metal vapor-deposited films, inorganic oxide vapor-deposited films, carbon-containing inorganic oxide vapor-deposited films, or films with these vapor-deposited films can be used. As films with vapor-deposited films, for example, aluminum vapor-deposited films and inorganic oxide vapor-deposited films can be used. These can be used individually or in combination of two or more types. As the barrier layer 13, metal foil is preferred in terms of mass (specific gravity), moisture resistance, processability, and cost, and aluminum foil is more preferred.

[0042] As for the aluminum foil, soft aluminum foil that has undergone annealing treatment is particularly preferred because it can provide the desired ductility during molding. However, it is even more preferable to use aluminum foil containing iron (aluminum alloy foil) in order to provide further pinhole resistance and ductility during molding. The iron content in the aluminum foil is preferably 0.1 to 9.0% by mass, and more preferably 0.5 to 2.0% by mass, of 100% by mass of aluminum foil. By having an iron content of 0.1% by mass or more, an exterior material 10 with better pinhole resistance and ductility can be obtained. By having an iron content of 9.0% by mass or less, an exterior material 10 with better flexibility can be obtained. As for the aluminum foil, untreated aluminum foil may be used, but it is preferable to use degreased aluminum foil in order to provide corrosion resistance. When degreasing the aluminum foil, the degreasing treatment may be applied to only one side of the aluminum foil, or to both sides.

[0043] The thickness of the barrier layer 13 is not particularly limited, but it is preferably 9 to 200 μm, and more preferably 15 to 100 μm, considering barrier properties, pinhole resistance, and processability.

[0044] <First and second corrosion-preventive treatment layers 14a, 14b> The first and second corrosion-preventive treatment layers 14a and 14b are layers provided to prevent corrosion of the metal foil (metal foil layer) and other materials constituting the barrier layer 13. The first corrosion-preventive treatment layer 14a also plays a role in increasing the adhesion between the barrier layer 13 and the first adhesive layer 12a. The second corrosion-preventive treatment layer 14b also plays a role in increasing the adhesion between the barrier layer 13 and the adhesive resin layer 15. The first corrosion-preventive treatment layer 14a and the second corrosion-preventive treatment layer 14b may be layers with the same composition or layers with different compositions. The first and second corrosion-preventive treatment layers 14a and 14b (hereinafter also simply referred to as "corrosion-preventive treatment layers 14a and 14b") may be formed by, for example, degreasing, hot water modification, anodizing, chemical conversion, or a combination thereof.

[0045] 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 individually, or mixtures thereof. Furthermore, as an acid degreasing method, using an acid degreasing agent obtained by dissolving a fluorine-containing compound such as monosodium ammonium difluoride in the above inorganic acid not only provides a degreasing effect on aluminum, especially when aluminum foil is used for the barrier layer 13, but also allows the formation of a passive aluminum fluoride, which is effective in terms of corrosion resistance. Alkaline degreasing methods include using sodium hydroxide, etc.

[0046] Examples of hydrothermal alteration treatments include the boehmite treatment, which involves immersing aluminum foil in boiling water to which triethanolamine has been added. Examples of anodizing treatments include the anodizing treatment.

[0047] Chemical treatments can be immersion-type or coating-type. Immersion-type chemical treatments include, for example, chromate treatment, zirconium treatment, titanium treatment, vanadium treatment, molybdenum treatment, calcium phosphate treatment, strontium hydroxide treatment, cerium treatment, ruthenium treatment, or various chemical treatments consisting of mixed phases of these. On the other hand, a coating-type chemical treatment is a method of applying a coating agent having corrosion-preventive properties onto the barrier layer 13.

[0048] Of these corrosion prevention treatments, if at least a portion of the corrosion prevention treatment layer is formed by hot water modification treatment, anodic oxidation treatment, or chemical conversion treatment, it is preferable to perform the degreasing treatment described above beforehand. Furthermore, if a degreased metal foil, such as a metal foil that has undergone an annealing process, is used as the barrier layer 13, it is not necessary to perform degreasing treatment again when forming the corrosion prevention treatment layers 14a and 14b.

[0049] The coating agent used in the coating-type chemical conversion treatment preferably contains trivalent chromium. The coating agent may also contain at least one polymer selected from the group consisting of cationic polymers and anionic polymers, as described later.

[0050] Furthermore, in particular, the hydrothermal alteration treatment and anodic oxidation treatment among the above treatments dissolve the surface of the aluminum foil with a treatment agent, forming aluminum compounds (boehmite, anodized aluminum) with excellent corrosion resistance. As a result, a co-continuous structure is formed from the barrier layer 13 using aluminum foil to the corrosion-preventive treatment layers 14a and 14b, and therefore the above treatment is included in the definition of chemical conversion treatment. On the other hand, as will be described later, it is also possible to form the corrosion-preventive treatment layers 14a and 14b using only a pure coating method that is not included in the definition of chemical conversion treatment. One example of this method is to use a sol of a rare earth element oxide such as cerium oxide with an average particle size of 100 nm or less, which has an aluminum corrosion-preventive effect (inhibitor effect) and is also environmentally suitable. By using this method, it is possible to impart a corrosion-preventive effect to metal foils such as aluminum foil even with a general coating method.

[0051] Examples of sols for the above-mentioned rare earth element oxides include sols using various solvents such as aqueous, alcoholic, hydrocarbon, ketone, ester, and ether-based solvents. Among these, aqueous sols are preferred.

[0052] In the sols of the rare earth element oxides mentioned above, inorganic acids such as nitric acid, hydrochloric acid, and phosphoric acid, or their salts, or organic acids such as acetic acid, malic acid, ascorbic acid, and lactic acid are usually used as dispersion stabilizers to stabilize their dispersion. Of these dispersion stabilizers, phosphoric acid in particular is expected to provide the following benefits in the exterior material 10: (1) stabilization of sol dispersion, (2) improved adhesion with the barrier layer 13 by utilizing the aluminum chelating ability of phosphoric acid, (3) imparting corrosion resistance by capturing (passivating) aluminum ions dissolved due to the effects of acids and corrosive gases, and (4) improved cohesive force of the corrosion prevention treatment layers (oxide layers) 14a and 14b due to the ease with which dehydration condensation of phosphoric acid occurs even at low temperatures.

[0053] The corrosion-preventive treatment layers 14a and 14b formed by the above-mentioned rare earth element oxide sols are aggregates of inorganic particles, and therefore, even after the drying and curing process, the cohesive force of the layers themselves may decrease. Therefore, in this case, it is preferable that the corrosion-preventive treatment layers 14a and 14b are compounded with an anionic polymer or a cationic polymer to compensate for the cohesive force.

[0054] The corrosion-preventive treatment layers 14a and 14b are not limited to the layers described above. For example, they may be formed using a treatment agent that combines a resin binder (such as aminophenol) with phosphoric acid and a chromium compound, as is known with coated chromate. Using this treatment agent, a layer can be formed that possesses both corrosion-preventive function and adhesion. Furthermore, although it is necessary to consider the stability of the coating liquid, a layer can be formed that possesses both corrosion-preventive function and adhesion by using a coating agent that pre-mixes a rare earth element oxide sol with a polycationic polymer or a polyanionic polymer into a single liquefaction.

[0055] The mass per unit area of the corrosion prevention treatment layers 14a and 14b is 0.005 to 0.200 g / m 2 preferably, and 0.010 to 0.100 g / m 2 is more preferable. If the mass per unit area is 0.005 g / m 2 or more, it is easy to impart a corrosion prevention function to the barrier layer 13. Also, even if the mass per unit area exceeds 0.200 g / m 2 , the corrosion prevention function does not change much. On the other hand, when using a rare earth element oxide sol, if the coating film is thick, curing due to heat during drying may be insufficient, and there is a risk of a decrease in cohesive force. The thickness of the corrosion prevention treatment layers 14a and 14b can be converted from their specific gravity.

[0056] From the viewpoint of easily maintaining the adhesion between the sealant layer and the barrier layer, the corrosion prevention treatment layers 14a and 14b may be, for example, in an embodiment containing cerium oxide, 1 to 100 parts by mass of phosphoric acid or phosphate with respect to 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.

[0057] <Sealant layer 16> The sealant layer 16 is a layer that imparts heat-sealing property to the exterior material 10, and is a layer that is disposed inside during the assembly of the power storage device and is heat-sealed (heat-fused). The sealant layer 16 contains a polypropylene-based resin (A1) (hereinafter also referred to as the "(A1) component") and an incompatible component (B1) (hereinafter also referred to as the "(B1) component") that is incompatible with the polypropylene-based resin. Having no compatibility (incompatible system) means that it disperses in the (A1) component with a dispersed phase size of 500 nm or more and less than 20 μm.

[0058] Component (A1) is a resin obtained from a polymerized monomer containing propylene. Examples of component (A1) include homopolypropylene and random polypropylene, and from the viewpoint of heat resistance, homopolypropylene is preferred. Examples of random polypropylene include copolymers of polypropylene and olefins other than polypropylene. Examples of olefins include ethylene, butene and octene. One olefin may be used alone or two or more may be used in combination. Component (A1) may be used alone or two or more may be used in combination.

[0059] (A1) The melting point of component (A1) is preferably 150°C to 175°C, and more preferably 160°C to 170°C, from the viewpoint of heat resistance.

[0060] Component (B1) may include, for example, polyolefin-based components. Polyolefin-based components are compounds having a structure derived from olefins. Examples of polyolefin-based components include polyethylene-based components, polybutene-based components, and polymethylpentene-based components, with polyethylene-based components being preferred from the viewpoint of stress relaxation ability. Polyethylene-based components are compounds having a structure derived from ethylene. Polybutene-based components are compounds having a structure derived from butene. Polymethylpentene-based components are compounds having a structure derived from methylpentene. Component (B1) may be a resin or an elastomer. Examples of elastomers include polyolefin-based elastomers using α-olefin as a comonomer. Component (B1) may include homopolymers, graft copolymers, block copolymers, and random copolymers. These copolymers have at least a portion that is incompatible with component (A). The copolymer may be a copolymer obtained by polymerizing two types, a terpolymer obtained by polymerizing three types, or a copolymer obtained by polymerizing four or more types.

[0061] Preferred polyethylene components include low-density polyethylene resin (LDPE), medium-density polyethylene resin (MDPE), linear low-density polyethylene resin (LLDPE), and ethylene-α-olefin copolymers. Preferred ethylene-α-olefin copolymers include, for example, copolymers of ethylene and propylene, copolymers of ethylene and butene, copolymers of ethylene and methylpentene, and copolymers of ethylene and octene.

[0062] The content of ethylene-derived structures in polyethylene-based components may be 60% by mass or more, 70% by mass or more, 80% by mass or more, or 90% by mass or more, based on the total amount of polyethylene-based components.

[0063] The content of polyolefin components in component (B1) may be 60% by mass or more, 70% by mass or more, 80% by mass or more, or 90% by mass or more, based on the total amount of component (B1).

[0064] The total content of components (A1) and (B1) in the sealant layer 16 may be 70% by mass or more, 80% by mass or more, or 90% by mass or more, based on the total amount of the sealant layer.

[0065] The proportion of component (A1) to the total mass of components (A1) and (B1) may be, for example, 70% by mass or more, 80% by mass or more, or 90% by mass or more, and may be 93% by mass or less, 95% by mass or less, or 97% by mass or less.

[0066] Figure 2 is a schematic diagram of a cross-section of the sealant layer 16 along the TD direction (perpendicular to the machine feed direction). As shown in Figure 2, the sealant layer 16 has a sea-island structure in which component (A1) 31 is the sea and component (B1) 32 is the island. When observing the cross-section of the sealant layer 16 along the TD direction, the area ratio S1 of component (B1) in the cross-section is preferably 15% or more, and more preferably 20% or more, as 10% or more provides sufficient stress relaxation and further improves scratch resistance. The area ratio S1 is preferably 40% or less, and more preferably 35% or less, as 50% or less tends to make the sealant layer 16 harder and further improve scratch resistance.

[0067] Figure 3 is a schematic diagram of a cross-section of the sealant layer 16 along the MD direction (machine feed direction). In the cross-section along the MD direction, the (B1) component 32 extends along the MD direction compared to the cross-section along the TD direction. When observing the cross-section of the sealant layer 16 along the MD direction, the area ratio S2 of the (B1) component in the cross-section tends to improve scratch resistance, so it is preferable to have a ratio of 10% or more. The area ratio S2 tends to improve scratch resistance, so it is preferable to have a ratio of 40% or less, more preferably 30% or less, and even more preferably 25% or less.

[0068] The ratio S1 / S2 of area ratio S1 to area ratio S2 is preferably greater than 1, more preferably 1.1 or greater, and even more preferably 1.5 or greater, as this tends to further improve scratch resistance. From a similar viewpoint, S1 / S2 is preferably 5.0 or less, more preferably 2.5 or less, and even more preferably 2.0 or less.

[0069] Area ratios S1 and S2 can be measured by observing cross-sections along the TD and MD directions, respectively, using a scanning electron microscope (SEM), binarizing the observed images, and calculating the areas of the island and sea portions. Specifically, these can be measured by the method described in the embodiments below.

[0070] The major axis of component (B1) in the cross-section along the TD direction of the sealant layer may be 0.01 μm or more, and is preferably 0.03 μm or more, and more preferably 0.05 μm or more, as this tends to further improve scratch resistance by suppressing the rebound of stress applied to the exterior material. The major axis of component (B1) in the cross-section along the TD direction may be 5 μm or less, and is preferably 4 μm or less, and more preferably 3 μm or less, as this tends to further improve scratch resistance by easing the stress applied to the exterior material. The major axis of component (B1) in the cross-section along the TD direction is measured by observing the cross-section with a scanning electron microscope.

[0071] The major axis of component (B1) in the cross-section along the MD direction of the sealant layer may be 0.2 μm or more, and is preferably 0.3 μm or more, and more preferably 0.5 μm or more, as this tends to suppress the rebound of stress applied to the exterior material and further improve scratch resistance. The major axis of component (B1) in the cross-section along the MD direction may be 15 μm or less, and is preferably 12.5 μm or less, and more preferably 10 μm or less, as this tends to relax the stress applied to the exterior material and further improve scratch resistance. The major axis of component (B1) in the cross-section along the MD direction is measured by observing the cross-section with a scanning electron microscope.

[0072] The sealant layer 16 may contain additives such as slip agents, antiblocking agents, antioxidants, light stabilizers, crystal nucleating agents, and flame retardants. Preferably, the content of these additives is 5 parts by mass or less when the total mass of the sealant layer 16 is 100 parts by mass.

[0073] The melting peak temperature of the sealant layer 16 varies depending on the application, but for exterior materials for all-solid-state batteries, it is preferably 160 to 280°C because it improves heat resistance.

[0074] The thickness of the sealant layer 16 is preferably greater than that of the adhesive resin layer 15, as this tends to further improve scratch resistance. From a similar viewpoint, the ratio of the thickness of the sealant layer 16 to the thickness of the adhesive resin layer 15 (thickness of sealant layer 16 / thickness of adhesive resin layer 15) is preferably 1.1 or greater, more preferably 1.5 or greater, and from a similar viewpoint, preferably 10 or less, and more preferably 3 or less.

[0075] The combined thickness of the sealant layer 16 and the adhesive resin layer 15 may be 15 to 300 μm, and from the viewpoint of sealing performance and water vapor barrier properties, 25 to 150 μm is preferred, and 50 to 100 μm is more preferred.

[0076] <Adhesive resin layer 15> The adhesive resin layer 15 contains a polypropylene resin (A2) (hereinafter also referred to as "component (A2)") and an incompatible component (B2) that is incompatible with the polypropylene resin (hereinafter also referred to as "component (B2)"). Incompatible means that it is dispersed in component (A2) with a dispersed phase size of 500 nm or more and less than 20 μm.

[0077] Component (A2) may be the same material as component (A1), but the adhesive resin layer 15 preferably contains an acid-modified polyolefin resin.

[0078] The acid-modified polyolefin resin may be a polyolefin resin modified with maleic anhydride, carboxylic acids, sulfonic acids, and their derivatives. The acid-modified polyolefin resin may be, for example, a graft copolymer, a block copolymer, and 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.

[0079] When observing a cross-section of the adhesive resin layer 15 along the TD direction, the area ratio S3 of component (B2) in the cross-section tends to further improve scratch resistance, so it is preferably 20% or more, more preferably 30% or more, and even more preferably 40% or more. From a similar viewpoint, the area ratio S3 is preferably 70% or less, more preferably 60% or less, and even more preferably 50% or less.

[0080] When observing a cross-section of the adhesive resin layer 15 along the MD direction, the area ratio S4 of component (B2) in the cross-section tends to further improve scratch resistance, so it is preferably 20% or more, and more preferably 25% or more. From a similar viewpoint, the area ratio S4 is preferably 60% or less, more preferably 55% or less, and even more preferably 50% or less.

[0081] The ratio S3 / S4 of area ratio S3 to area ratio S4 is preferably greater than 1, more preferably 1.1 or greater, and even more preferably 1.2 or greater, as this tends to further improve scratch resistance. From a similar viewpoint, S3 / S4 is preferably 5.0 or less, and more preferably 4.0 or less.

[0082] The ratio S3 / S1 of area ratio S3 to area ratio S1 is preferably greater than 1, more preferably 1.1 or greater, and even more preferably 1.2 or greater, as this tends to further improve scratch resistance. From a similar viewpoint, S3 / S1 is preferably 6 or less, and more preferably 3 or less.

[0083] Area ratios S3 and S4 can be measured by observing cross-sections along the TD and MD directions, respectively, using a scanning electron microscope (SEM), binarizing the observed images, and calculating the areas of the island and sea portions. Specifically, these can be measured by the method described in the embodiments below.

[0084] The major axis of component (B2) in the cross-section of the adhesive resin layer 15 along the TD and MD directions may be the same as the major axis of component (B1) in the cross-section of the sealant layer along the TD and MD directions. The method for measuring the major axis of component (B2) in the cross-section of the adhesive resin layer 15 along the TD and MD directions may be the same as the method for measuring the major axis of component (B1) in the cross-section of the sealant layer along the TD and MD directions.

[0085] The adhesive resin layer 15 may optionally contain various additives such as various compatible and incompatible elastomers, flame retardants, slip agents, antiblocking agents, antioxidants, light stabilizers, crystal nucleating agents, and tackifiers.

[0086] When an exterior material, such as exterior material 10, includes an adhesive resin layer 15 and a sealant layer 16, the resin compositions for forming each layer may be prepared separately and laminated by the T-die method or the inflation method, or one layer may be formed and then another layer may be extruded onto it, or each layer may be made by the T-die method or the inflation method and then bonded together with an adhesive. As for the adhesive to be used, an agent containing acid-modified polypropylene and a curing agent (e.g., isocyanate) can be used from the viewpoint of interfacial adhesion.

[0087] The resins in the adhesive resin layer 15 and the sealant layer 16 can be analyzed using known analytical methods such as IR, NMR, various mass (mass) analysis methods, X-ray analysis, Raman spectroscopy, GPC, DSC, and DMA.

[0088] Although preferred embodiments of the exterior material for energy storage devices of this embodiment have been described in detail above, this disclosure is not limited to such specific embodiments, and various modifications and changes are possible within the scope of the gist of this disclosure as described in the claims.

[0089] For example, Figure 1 shows a case where corrosion-preventive treatment layers 14a and 14b are provided on both sides of the barrier layer 13, but only one of the corrosion-preventive treatment layers 14a and 14b may be provided, or neither corrosion-preventive treatment layer may be provided. Figure 1 shows a case where a first adhesive layer 12a is provided, but the first adhesive layer 12a may not be provided.

[0090] Figure 1 shows the case where the sealant layer is a single layer, but the sealant layer may be multilayered. In this case, area ratio S1 is the weighted average value obtained by weighting the area ratio of the (B1) component in the cross-section along the TD direction of each layer based on the thickness of each layer. Area ratio S2 is the weighted average value obtained by weighting the area ratio of the (B1) component in the cross-section along the MD direction of each layer based on the thickness of each layer.

[0091] Figure 1 shows a case where the barrier layer 13 and sealant layer 16 are laminated using an adhesive resin layer 15. However, as shown in Figure 4, the barrier layer 13 and sealant layer 16 may also be laminated using a second adhesive layer 12b, as in the exterior material 20 for energy storage devices. It is preferable to include a second adhesive resin layer in the exterior material, as this tends to further improve scratch resistance.

[0092] <Second adhesive layer 12b> 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.

[0093] If a corrosion-preventive treatment layer 14b is provided on the barrier layer 13, and the second corrosion-preventive treatment layer 14b has a layer containing at least one polymer selected from the group consisting of cationic polymers and anionic polymers described above, it is preferable that the second adhesive layer 12b is a layer containing a compound that is reactive with the polymer contained in the second corrosion-preventive treatment layer 14b (hereinafter also referred to as "reactive compound").

[0094] For example, if the second corrosion-preventive treatment layer 14b contains a cationic polymer, it is preferable that the second adhesive layer 12b contains a compound that is reactive with the cationic polymer. If the second corrosion-preventive treatment layer 14b contains an anionic polymer, it is preferable that the second adhesive layer 12b contains a compound that is reactive with the anionic polymer. Furthermore, if the second corrosion-preventive treatment layer 14b contains both a cationic polymer and an anionic polymer, it is preferable that the second adhesive layer 12b contains a compound that is reactive with the cationic polymer and a compound that is reactive with the anionic polymer. However, the second adhesive layer 12b does not necessarily have to contain the above two types of compounds, and may contain a compound that is 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 further contain an acid-modified polyolefin resin.

[0095] Compounds that react with cationic polymers include at least one compound selected from the group consisting of polyfunctional isocyanate compounds, glycidyl compounds, compounds having a carboxyl group, and compounds having an oxazoline group.

[0096] Examples of these polyfunctional isocyanate compounds, glycidyl compounds, compounds having a carboxyl group, and compounds having an oxazoline group include the polyfunctional isocyanate compounds, glycidyl compounds, compounds having a carboxyl group, and compounds having an oxazoline group that were previously exemplified as crosslinking agents for creating a crosslinked structure of cationic polymers. Among these, polyfunctional isocyanate compounds are preferred because they have high reactivity with cationic polymers and readily form crosslinked structures.

[0097] Compounds that react with anionic polymers include at least one compound selected from the group consisting of glycidyl compounds and compounds having an oxazoline group. Examples of these glycidyl compounds and compounds having an oxazoline group include the glycidyl compounds and compounds having an oxazoline group that were previously exemplified as crosslinking agents for creating a crosslinked structure of cationic polymers. Among these, glycidyl compounds are preferred due to their high reactivity with anionic polymers.

[0098] When the second adhesive layer 12b contains an acid-modified polyolefin resin, it is preferable that the reactive compound is also reactive with the acidic groups in the acid-modified polyolefin resin (i.e., forms a covalent bond with the acidic groups). This further improves adhesion to the second corrosion-preventive treatment layer 14b. In addition, the acid-modified polyolefin resin becomes a cross-linked structure, further improving the solvent resistance of the exterior material 20.

[0099] The content of the reactive compound is preferably equal to or 10 times the amount of the acidic groups in the acid-modified polyolefin resin. If the amount is equal to or greater than the amount, 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 amount, the crosslinking reaction with the acid-modified polyolefin resin will be sufficiently saturated, and unreacted material will be present, raising concerns about a decrease in various performance characteristics. 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.

[0100] Acid-modified polyolefin resins are polyolefin resins into which acidic groups have been introduced. Examples of acidic groups include carboxyl groups, sulfonic acid groups, and acid anhydride groups, with maleic anhydride groups and (meth)acrylic acid groups being particularly preferred. As an acid-modified polyolefin resin, for example, the same type as the modified polyolefin resin used in the sealant layer 16 can be used.

[0101] The second adhesive layer 12b may contain various additives such as flame retardants, slip agents, antiblocking agents, antioxidants, light stabilizers, and tackifiers.

[0102] The second adhesive layer 12b may, from the viewpoint of suppressing a decrease in heat seal strength when corrosive gases such as hydrogen sulfide or electrolytes are involved, and from the viewpoint of further suppressing a decrease in insulating properties, include, 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 carboxyl group, a compound having an oxazoline group, and a carbodiimide compound. Examples of carbodiimide compounds 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.

[0103] Furthermore, as the adhesive forming the second adhesive layer 12b, for example, a polyurethane-based adhesive containing a polyester polyol composed of hydrogenated dimer fatty acids and diols, and a polyisocyanate can be used. Examples of adhesives include polyurethane resins obtained by reacting a bifunctional or more isocyanate compound with a main component such as a polyester polyol, polyether polyol, acrylic polyol, or carbonate polyol, and epoxy resins obtained by reacting an amine compound with a main component having epoxy groups, which are preferred from the viewpoint of heat resistance.

[0104] 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 to 10 μm, and more preferably 2 to 7 μm.

[0105] [Manufacturing method for exterior materials] Next, an example of a manufacturing method for the exterior material 10 shown in Figure 1 will be described. Note that the manufacturing method for the exterior material 10 is not limited to the method described below.

[0106] The manufacturing method for the exterior material 10 of this embodiment generally includes the steps of: providing corrosion-preventive treatment layers 14a and 14b on the barrier layer 13; bonding the base material layer 11 and the barrier layer 13 using the first adhesive layer 12a; further laminating an adhesive resin layer 15 and a sealant layer 16 on the surface of the barrier layer 13 facing the corrosion-preventive treatment layer 14b to produce a laminate; and, if necessary, aging the obtained laminate.

[0107] (Lamination process of corrosion-preventive treatment layers 14a and 14b onto barrier layer 13) This process involves forming corrosion-preventive treatment layers 14a and 14b on the barrier layer 13. As mentioned above, methods for this include degreasing, hot water modification, anodizing, chemical conversion, or applying a coating agent with corrosion-preventive properties to the barrier layer 13.

[0108] Furthermore, if the corrosion prevention treatment layers 14a and 14b are multilayered, for example, the coating liquid (coating agent) constituting the lower layer (barrier layer 13 side) of the corrosion prevention treatment layer can be applied to the barrier layer 13 and baked to form the first layer, and then the coating liquid (coating agent) constituting the upper layer of the corrosion prevention treatment layer can be applied to the first layer and baked to form the second layer.

[0109] Degreasing can be performed by spraying or immersion. Hot water modification and anodizing can be performed by immersion. For chemical conversion treatments, immersion, spraying, coating, etc., can be appropriately selected depending on the type of chemical conversion treatment.

[0110] Various methods can be used for applying coatings with corrosion-preventive properties, including gravure coating, reverse coating, roll coating, and bar coating.

[0111] As described above, the various treatments may be applied to either one or both sides of the metal foil, but in the case of single-sided treatment, it is preferable to apply the treatment to the side on which the sealant layer 16 is laminated. Furthermore, the above treatment may also be applied to the surface of the base layer 11, if required.

[0112] Furthermore, the amount of coating agent applied to form both the first and second layers is 0.005 to 0.200 g / m². 2 Preferably, 0.010 to 0.100 g / m 2 This is preferable.

[0113] Furthermore, if drying curing is required, it can be carried out at a base material temperature in the range of 60 to 300°C, depending on the drying conditions of the corrosion-preventive treatment layers 14a and 14b used.

[0114] (Bonding process between the base layer 11 and the barrier layer 13) This process involves bonding a barrier layer 13, which is provided with corrosion-preventive treatment layers 14a and 14b, to a base material layer 11 via a first adhesive layer 12a. The base material layer 11 is bonded to the side of the barrier layer 13 facing the corrosion-preventive treatment layer 14a. The bonding method can be dry lamination, non-solvent lamination, wet lamination, or other methods, and the two are bonded using the material that constitutes the first adhesive layer 12a described above. The dry application amount of the first adhesive layer 12a is preferably 1 to 10 g / m². 2 In the range of 2 to 7 g / m², more preferably 2 to 7 g / m² 2 It will be established within the range of [this].

[0115] (Lamination process of adhesive resin layer 15 and sealant layer 16) This process involves forming an adhesive resin layer 15 and a sealant layer 16 on the surface of the barrier layer 13 facing the corrosion-preventive treatment layer 14b. One method for this is sand lamination of the adhesive resin layer 15 together with the sealant layer 16 using an extrusion laminating machine. Furthermore, lamination is also possible using tandem lamination or co-extrusion methods, in which the adhesive resin layer 15 and the sealant layer 16 are extruded. In forming the adhesive resin layer 15 and the sealant layer 16, for example, each component is blended to satisfy the above-described configuration of the adhesive resin layer 15 and the sealant layer 16. For forming the adhesive resin layer 15, a resin composition for forming a sealant layer containing the above-described components of the adhesive resin layer 15 is used. For forming the sealant layer 16, a resin composition for forming a sealant layer containing the above-described components of the sealant layer 16 is used.

[0116] This process yields a laminate in which each layer is laminated in the following order, as shown in Figure 1: base material layer 11 / first adhesive layer 12a / first corrosion prevention treatment layer 14a / barrier layer 13 / second corrosion prevention treatment layer 14b / adhesive resin layer 15 / sealant layer 16.

[0117] The adhesive resin layer 15 may be laminated by directly extruding the dry-blended material using an extrusion laminating machine to achieve the material composition described above. Alternatively, the adhesive resin layer 15 may be laminated by extruding the granulated material, which has been melt-blended using a melt-kneading device such as a single-screw extruder, twin-screw extruder, or Brabender mixer, using an extrusion laminating machine.

[0118] The area ratios S3 and S4 in the adhesive resin layer 15 can be adjusted as appropriate by changing the amount of component (B2) in the resin composition for forming the adhesive resin layer.

[0119] The sealant layer 16 may be laminated by directly extruding a dry-blended material, which has been prepared to have the above-described material composition as a component of the resin composition for forming the sealant layer, using an extrusion laminating machine. Alternatively, the adhesive resin layer 15 and the sealant layer 16 may be laminated by a tandem lamination method or co-extrusion method, in which the adhesive resin layer 15 and the sealant layer 16 are extruded using an extrusion laminating machine after melt blending the granulated material using a melt-kneading device such as a single-screw extruder, twin-screw extruder, or Bravender mixer. Furthermore, a single sealant film may be prepared in advance as a cast film using the resin composition for forming the sealant layer, and this film may be laminated together with the adhesive resin by sand lamination. From the viewpoint of productivity, the formation speed (processing speed) of the adhesive resin layer 15 and the sealant layer 16 can be, for example, 80 m / min or more.

[0120] The area ratios S1 and S2 in the sealant layer 16 can be adjusted as appropriate by changing the amount of component (B1) in the resin composition for forming the sealant layer.

[0121] (Aging process) This process involves aging (curing) the laminate. Aging the laminate promotes adhesion between the base layer 11, the first adhesive layer 12a, the first corrosion-preventive treatment layer 14a, and the barrier layer 13, as well as adhesion between the barrier layer 13, the second corrosion-preventive treatment layer 14b, the second adhesive layer 12b, and the sealant layer 16. Aging the laminate also reduces the area ratios S2 and S4. 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 more, 2 hours or more, or 3 hours or more, and may be 24 hours or less, 48 ​​hours or less, or 72 hours or less.

[0122] In this way, the exterior material 10 of this embodiment, as shown in Figure 1, can be manufactured.

[0123] Next, an example of a manufacturing method for the exterior material 20 shown in Figure 4 will be described. Note that the manufacturing method for the exterior material 20 is not limited to the method described below.

[0124] The manufacturing method for the exterior material 20 of this embodiment generally includes the steps of: providing corrosion-preventive treatment layers 14a and 14b on the barrier layer 13; bonding the base layer 11 and the barrier layer 13 using a first adhesive layer 12a; bonding a sealant layer 16 to the corrosion-preventive treatment layer 14b side of the barrier layer 13 via a second adhesive layer 12b to obtain a laminate; and, if necessary, aging the obtained laminate. The steps up to bonding the base layer 11 and the barrier layer 13 using the first adhesive layer 12a can be carried out in the same manner as the manufacturing method for the exterior material 10 described above. The step of aging the obtained laminate can be carried out in the same manner as the manufacturing method for the exterior material 10 described above.

[0125] (Lamination process of the second adhesive layer 12b and sealant layer 16) This process involves bonding a sealant layer 16 to the corrosion-preventive treatment layer 14b side of the barrier layer 13 via a second adhesive layer 12b to obtain a laminate. Methods of bonding include wet processes and dry lamination.

[0126] In the wet process, a solution or dispersion of the adhesive constituting the second adhesive layer 12b is applied onto the corrosion-preventive treatment layer 14b, and the solvent is evaporated at a predetermined temperature to form a dry film, or a baking treatment is performed as needed after drying. Subsequently, a sealant layer 16 is laminated to manufacture the exterior material 20. Examples of coating methods include the various coating 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.

[0127] In this case, the sealant layer 16 can be manufactured by a melt extrusion molding machine using, for example, a resin composition for forming a sealant layer containing the components of the sealant layer 16 described above. From the viewpoint of productivity, the processing speed of the melt extrusion molding machine can be set to 80 m / min or more.

[0128] The exterior material for energy storage devices disclosed herein can be suitably used as an exterior material for energy storage devices such as secondary batteries including lithium-ion batteries, nickel-metal hydride batteries, and lead-acid batteries, as well as electrochemical capacitors such as electric double-layer capacitors. In particular, the exterior material for energy storage devices disclosed herein is suitable as an exterior material for all-solid-state batteries using solid electrolytes that are expected to be used in high-temperature environments after heat sealing, as it can maintain excellent heat-sealing properties even when used in high-temperature environments after heat sealing.

[0129] [Energy storage devices] Figure 5 is a perspective view showing one embodiment of an energy storage device fabricated using the exterior material described above. As shown in Figure 5, the energy storage device 50 is composed of a battery element (energy storage device body) 52 including electrodes, two metal terminals (leads, current extraction terminals) 53 extending from the electrodes for extracting current from the battery element 52 to the outside, and an exterior material 10 that hermetically encloses the battery element 52. The exterior material 10 is the exterior material 10 according to the embodiment described above and is used as a container for housing the battery 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 material 10 is constructed to enclose the battery element 52 inside by folding one laminate film in half and heat-sealing the periphery, or by overlapping two laminate films and heat-sealing the periphery, so that the base material layer 11 is on the outside side of the energy storage device 50 and the sealant layer 16 is on the inside side of the energy storage device 50. The metal terminal 53 is sandwiched and sealed by the outer material 10 that forms the container with the sealant layer 16 on the inside. The metal terminal 53 may also be sandwiched by the outer material 10 via a tab sealant. In the energy storage device 50, an outer material 20 may be used instead of the outer material 10.

[0130] The battery element 52 has an electrolyte interposed between the positive electrode and the negative electrode. The metal terminal 53 is a part of the current collector that is exposed to the outside of the outer casing material 10, and is made of metal foil such as copper foil or aluminum foil.

[0131] The energy storage device 50 of this embodiment may be an all-solid-state battery. In this case, a solid electrolyte such as a sulfide-based solid electrolyte is used as the electrolyte of the battery element 52. Because the energy storage device 50 of this embodiment uses the exterior material 10 of this embodiment, pressure is applied uniformly to the battery element and tends to improve operating efficiency. [Examples]

[0132] The present disclosure will be described below in detail based on examples, but the present disclosure is not limited to these examples.

[0133] [Materials used] The materials used in the examples and comparative examples are shown below.

[0134] <Substrate layer (thickness 25 μm)> PET: A polyethylene terephthalate film with corona treatment applied to one side was used.

[0135] <First adhesive layer (mass per unit area: 4.0 g / m²) 2 )> An adhesive was used that was prepared by blending a polyester polyol (manufactured by Showa Denko Materials, product name: Teslac 2505-63, hydroxyl value: 7-11 mg KOH / g) and a nurate of isophorone diisocyanate (manufactured by Mitsui Chemicals, product name: Takenate 600) so that the NCO / OH ratio was 20.0, and then diluting it with ethyl acetate to a solid content of 26% by mass.

[0136] <Second adhesive layer (mass per unit area: 3.0 g / m²) 2 )> An adhesive was used, which consisted of 10 parts by mass (solid content ratio) of a polyisocyanate compound with an isocyanurate structure to 100 parts by mass of an acid-modified polyolefin resin dissolved in toluene.

[0137] <First corrosion-preventive treatment layer (substrate layer side) and second corrosion-preventive treatment layer (sealant layer side)> (CL-1): A "sodium polyphosphate stabilized cerium oxide sol" was used, which was prepared by adjusting the solid content to 10% by mass using distilled water as the solvent. The sodium polyphosphate stabilized cerium oxide sol was obtained by mixing 10 parts by mass of sodium phosphoric acid with 100 parts by mass of cerium oxide. (CL-2): A composition consisting of 90% by mass of "polyallylamine (manufactured by Nitto Boseki Co., Ltd.)" and 10% by mass of "polyglycerol polyglycidyl ether (manufactured by Nagase ChemteX Corporation)" was used, adjusted to a solid content concentration of 5% by mass using distilled water as a solvent.

[0138] <Barrier layer (thickness 40 μm)> AL: Annealed and degreased soft aluminum foil (manufactured by Toyo Aluminum Co., Ltd., "8079 material") was used.

[0139] <Adhesive resin layer and sealant layer> The materials used for the adhesive resin layer and sealant layer are shown in Table 1 below.

[0140] [Table 1]

[0141] [Manufacturing of exterior materials] (Example 1) First, the barrier layer was coated with a first and second corrosion-preventive treatment layer using the following procedure: (CL-1) was applied to both surfaces of the barrier layer at a dry application rate of 70 mg / m². 2 The material was coated using microgravure coating and then baked in a drying unit at 200°C. Next, (CL-2) was applied to the resulting layer at a dry coating rate of 20 mg / m². 2 By applying a microgravure coating in this manner, a composite layer consisting of (CL-1) and (CL-2) was formed as the first and second corrosion-preventive treatment layers. This composite layer exhibits corrosion-preventive performance by combining the two types, (CL-1) and (CL-2).

[0142] Next, using a dry lamination method, the first adhesive (first adhesive layer) was used to bond the side of the barrier layer with the corrosion-preventive treatment layer facing the first corrosion-preventive treatment layer to the corona-treated side of the substrate layer to obtain the first laminate. The lamination of the barrier layer with the corrosion-preventive treatment layer and the substrate layer was performed by applying the first adhesive onto the first corrosion-preventive treatment layer, with a dry application amount (mass per unit area) of 4.0 g / m². 2 The coating was applied in this manner, dried at 80°C for 1 minute, laminated with the substrate layer, and then aged at 80°C for 120 hours.

[0143] Next, the first laminate was set in the unwinding section of an extrusion laminating machine. The adhesive resin layer and sealant layer were laminated in this order on the second corrosion-preventive treatment layer of the first laminate by co-extrusion from a T-die at processing conditions of 270°C and 80 m / min to obtain an exterior material (a laminate of base material layer / first adhesive layer / first corrosion-preventive treatment layer / barrier layer / second corrosion-preventive treatment layer / adhesive resin layer / sealant layer). For the lamination of the adhesive resin layer and sealant layer, the various materials shown in Table 2 were dry-blended in advance and used in the above extrusion lamination. The thickness of the adhesive resin layer and sealant layer was set to the values ​​shown in Table 3.

[0144] (Examples 2-5) A first laminate was obtained in the same manner as in Example 1. A second laminate was obtained by laminating an adhesive resin layer and a sealant layer in that order on the second corrosion-preventive treatment layer of the first laminate in the same manner as in Example 1. The second laminate was aged at the temperatures and times shown in Table 2 to obtain an exterior material.

[0145] (Examples 6-12, Comparative Examples 1-3) Exterior materials were obtained in the same manner as in Example 1, except that the materials shown in Table 2 were used as the materials for the adhesive resin layer and the sealant layer.

[0146] (Examples 13, 17) Exterior materials were obtained in the same manner as in Example 3, except that the materials shown in Table 2 were used as the materials for the adhesive resin layer and the sealant layer.

[0147] (Examples 14-16) Except for changing the thickness of the adhesive resin layer and sealant layer as shown in Table 3, an exterior material was obtained in the same manner as in Example 3.

[0148] (Example 18) A first laminate was obtained in the same manner as in Example 1. Next, using a dry lamination method, a sealant layer shown in Table 2 was bonded onto the second corrosion-preventive treatment layer of the first laminate using a second adhesive (second adhesive layer). The lamination of the first laminate and the sealant layer was performed by applying an adhesive for forming the second adhesive layer onto the second corrosion-preventive 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. An exterior material (a laminate of base material layer / first adhesive layer / first corrosion-preventive treatment layer / barrier layer / second corrosion-preventive treatment layer / second adhesive layer / sealant layer) was fabricated using the above method.

[0149] [Measurement of the area ratio of incompatible components (B)] (Examples 1-18 and Comparative Examples 1-3) After solidifying the exterior materials obtained in each example with resin, cross-sections of the exterior materials were cut using a Leica ultramicrotome. The ethylene-propylene copolymer component of the cross-section was stained with ruthenium tetroxide at 70°C for 2 to 4 hours. Platinum was deposited onto the stained cross-section. Then, images were taken of the target layer by observing the cross-section with a scanning electron microscope (observation magnification: 2000x). Observation was performed at three arbitrary locations on the cross-section of the target layer. An arbitrary region (10 μm square) was cut out from each of the three images. The cut-out region was binarized into a sea component and an island component using image processing software (ImageJ), and the proportion of the island component was calculated. Specifically, the cut-out region was converted to an 8-bit (256-level grayscale) image, the grayscale threshold between the sea component and the island component was set automatically, and the area ratio of the island component within the cut-out region was calculated by binarization. The average of the area ratios at three locations was used as the area ratio of the incompatible component (B) in the cross-section of the layer being observed. The observed areas were the cross-sections of the sealant layer and adhesive resin layer along the MD and TD directions. The results are shown in Table 3.

[0150] [Scratch resistance evaluation] (Examples 1-18 and Comparative Examples 1-3) A pencil hardness test was performed on the exterior materials obtained in each example. Specifically, the materials were subjected to a pencil hardness tester as specified in JIS K 5600 to check how scratches formed on the sealant layer of the exterior materials, and the pencil hardness was measured. The pencil hardness was evaluated on a five-point scale: "S", "A", "B", "C", and "D". The results are shown in Table 3. [Evaluation Criteria] S: If the pencil hardness is 5H or higher A: When the pencil hardness is 3H or higher but less than 4H B: When the pencil hardness is between 2H and 3H C: When the pencil hardness is H or higher but less than 2H D: If the pencil hardness is less than H

[0151] [Table 2]

[0152] [Table 3]

[0153] The gist of this disclosure is found in the following [1] to

[12] . [1] An exterior material for an energy storage device comprising, at least, a base layer, a barrier layer, and a sealant layer in this order, The sealant layer contains a polypropylene resin (A) and an incompatible component (B) that is incompatible with the polypropylene resin. An exterior material in which, when the cross-section of the sealant layer is observed along the TD direction, the area ratio S1 of the incompatible component (B) in the cross-section is 10-50%. [2] The exterior material according to [1], wherein when the cross-section of the sealant layer is observed along the MD direction, the area ratio S2 of the incompatible component (B) in the cross-section is 10-40%. [3] The exterior material described in [2], wherein the ratio S1 / S2 of the area ratio S1 to the area ratio S2 is greater than 1. [4] The barrier layer and the sealant layer are further provided with an adhesive resin layer, The adhesive resin layer contains a polypropylene resin (A) and an incompatible component (B) that is incompatible with the polypropylene resin. An exterior material according to any one of [1] to [3], wherein, when the cross-section of the adhesive resin layer is observed along the TD direction, the area ratio S3 of the incompatible component (B) in the cross-section is 20 to 70%. [5] The exterior material according to [4], wherein when the cross-section of the adhesive resin layer is observed along the MD direction, the area ratio S4 of the incompatible component (B) in the cross-section is 20-60%. [6] The exterior material described in [5], wherein the ratio S3 / S4 of the area ratio S3 to the area ratio S4 is greater than 1. [7] An exterior material according to any of [4] to [6], wherein the ratio S3 / S1 of the area ratio S3 to the area ratio S1 is greater than 1. [8] An exterior material according to any one of [4] to [7], wherein the sealant layer is thicker than the adhesive resin layer. [9] An exterior material according to any one of [1] to [8], wherein the non-miscible component (B) contains a polyethylene component.

[10] An outer covering material for all-solid-state batteries, as described in any of [1] to [9].

[11] The main body of the energy storage device, An exterior material described in any of [1] to

[10] that houses the main body of the energy storage device, A power storage device equipped with the following features.

[12] The energy storage device described in

[11] , which is an all-solid-state battery. [Explanation of Symbols]

[0154] 10, 20... Exterior material, 11... Base material layer, 13... Barrier layer, 15... Adhesive resin layer, 16... Sealant layer, 50... Energy storage device.

Claims

1. An exterior material for an energy storage device comprising, at least, a base layer, a barrier layer, and a sealant layer in this order, The sealant layer contains a polypropylene resin (A) and an incompatible component (B) that is incompatible with the polypropylene resin. When the cross-section of the sealant layer along the TD direction is observed, the area ratio S1 of the incompatible component (B) in the cross-section is 10 to 50%. When the cross-section of the sealant layer along the MD direction is observed, the area ratio S2 of the incompatible component (B) in the cross-section is 10 to 40%. An exterior material in which the ratio S1 / S2 of the area ratio S1 to the area ratio S2 is greater than 1.

2. The barrier layer and the sealant layer are further provided with an adhesive resin layer. The adhesive resin layer contains a polypropylene resin (A) and an incompatible component (B) that is incompatible with the polypropylene resin. The exterior material according to claim 1, wherein when the cross-section of the adhesive resin layer is observed along the TD direction, the area ratio S3 of the incompatible component (B) in the cross-section is 20 to 70%.

3. The exterior material according to claim 2, wherein when the cross-section of the adhesive resin layer is observed along the MD direction, the area ratio S4 of the incompatible component (B) in the cross-section is 20 to 60%.

4. The exterior material according to claim 3, wherein the ratio S3 / S4 of the area ratio S3 to the area ratio S4 is greater than 1.

5. The exterior material according to claim 2, wherein the ratio S3 / S1 of the area ratio S3 to the area ratio S1 is greater than 1.

6. The exterior material according to claim 2, wherein the sealant layer is thicker than the adhesive resin layer.

7. The exterior material according to claim 1 or 2, wherein the non-miscible component (B) includes a polyethylene component.

8. The exterior material according to claim 1 or 2, for use with all-solid-state batteries.

9. An exterior material for an energy storage device comprising, at least, a base layer, a barrier layer, and a sealant layer in this order, The sealant layer contains a polypropylene resin (A) and an incompatible component (B) that is incompatible with the polypropylene resin. When the cross-section of the sealant layer along the TD direction is observed, the area ratio S1 of the incompatible component (B) in the cross-section is 10 to 50%. The barrier layer and the sealant layer are further provided with an adhesive resin layer. The adhesive resin layer contains a polypropylene resin (A) and an incompatible component (B) that is incompatible with the polypropylene resin. When the cross-section of the adhesive resin layer along the TD direction is observed, the area ratio S3 of the incompatible component (B) in the cross-section is 20 to 70%. When the cross-section of the adhesive resin layer along the MD direction is observed, the area ratio S4 of the non-miscible component (B) in the cross-section is 20 to 60%. An exterior material in which the ratio S3 / S4 of the area ratio S3 to the area ratio S4 is greater than 1.

10. An exterior material for an energy storage device comprising, at least, a base layer, a barrier layer, and a sealant layer in this order, The sealant layer contains a polypropylene resin (A) and an incompatible component (B) that is incompatible with the polypropylene resin. When the cross-section of the sealant layer along the TD direction is observed, the area ratio S1 of the incompatible component (B) in the cross-section is 10 to 50%. The barrier layer and the sealant layer are further provided with an adhesive resin layer. The adhesive resin layer contains a polypropylene resin (A) and an incompatible component (B) that is incompatible with the polypropylene resin. When the cross-section of the adhesive resin layer along the TD direction is observed, the area ratio S3 of the incompatible component (B) in the cross-section is 20 to 70%. An exterior material in which the ratio S3 / S1 of the area ratio S3 to the area ratio S1 is greater than 1.

11. The main unit of the energy storage device, An exterior material according to claim 1 or 2 for housing the main body of the energy storage device, A power storage device equipped with the following features.

12. The energy storage device according to claim 11, which is an all-solid-state battery.

Images