Outer covering material for power storage device, and power storage device using same

Abstract

An outer covering material for a power storage device according to the present invention comprises a base material layer, a barrier layer including a metal foil layer, and a thermally fusible resin layer in this order. The outer covering material for a power storage device comprises a lubricant layer containing a lubricant on the surface of the thermally fusible resin layer. If the outer covering material for a power storage device is placed in an environment of 40°C or higher, the thermally fusible resin layer can take in the lubricant from the lubricant layer such that the amount of the lubricant layer is 10 mg / m2 or less.

Description

Sheathing material for power storage device and power storage device using the same

[0001] The present disclosure relates to an exterior material for a power storage device and a power storage device using the same.

[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] Lithium-ion batteries that use the above multilayer film as an exterior material are called laminated lithium-ion batteries. The exterior material covers a battery cell containing a positive electrode, a separator, a negative electrode, an electrolyte, etc., and prevents moisture from penetrating into the battery. Laminated lithium-ion batteries are manufactured, for example, by forming a recess in part of the exterior material by cold forming, accommodating the battery cell in the recess, folding back the remaining part of the exterior material, and heat-sealing the edges (see, for example, Patent Document 1).

[0004] JP 2013-101765 A

[0005] Research and development is currently being conducted on power storage devices known as all-solid-state batteries as the next generation of lithium-ion batteries. All-solid-state batteries are characterized by the use of a solid electrolyte rather than an organic electrolyte. While lithium-ion batteries cannot be used at temperatures higher than the boiling point of the electrolyte (approximately 80°C), all-solid-state batteries can be used at temperatures exceeding 100°C, and the conductivity of lithium ions can be increased by operating them at high temperatures (e.g., 100-150°C). Furthermore, the use of all-solid-state batteries can reduce the space and cost required for a cooling system to cool the battery.

[0006] However, such multilayer films may suffer from cracks or breakage when recesses are formed by cold forming, and there is still room for improvement in terms of formability.

[0007] Furthermore, such multilayer films are sometimes used as exterior containers for all-solid-state batteries. In such cases, battery cells are housed in the exterior container and held in a pressurized state via the multilayer film. However, all-solid-state batteries tend to reach high temperatures of 40°C or higher during operation, and if they are subjected to vibrations or the like at that time, the battery cells may slip relative to the multilayer film inside the exterior container. Therefore, exterior materials for all-solid-state batteries are required to be less likely to slip relative to the battery cells, even when the battery cells are placed in a pressurized, high-temperature environment of 40°C or higher.

[0008] Furthermore, not only all-solid-state batteries but also other power storage devices such as lithium ion capacitors that can be used at high temperatures are being developed, and therefore, the exterior materials of other power storage devices such as lithium ion capacitors are also required to be less likely to slip relative to the battery cells even when the battery cells are placed in a high-temperature environment of 40°C or higher with pressure applied to the battery cells.

[0009] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide an exterior material for a power storage device that has excellent formability and can suppress slippage on a battery cell even when the battery cell of the power storage device is placed in an environment of 40°C or higher while being pressurized, and a power storage device using the same.

[0010] In order to solve the above-described problems, one aspect of the present disclosure is an electrical storage device packaging material including a base material layer, a barrier layer including a metal foil layer, and a heat-sealable resin layer in this order, the electrical storage device packaging material including a base material layer, a barrier layer including a metal foil layer, and a heat-sealable resin layer, the heat-sealable resin layer having a lubricant layer containing a lubricant on a surface thereof, the heat-sealable resin layer taking in the lubricant from the lubricant layer when the electrical storage device packaging material is placed in an environment of 40°C or higher, and the amount of the lubricant layer being 10 mg / m ２ The present invention provides an exterior material for a power storage device that can achieve the following:

[0011] The above-mentioned electrical storage device packaging material includes a lubricant layer containing a lubricant on the surface of the heat-sealable resin layer. Therefore, when a recess is formed in the packaging material from the lubricant layer side using a mold, the mold easily slides on the lubricant layer, reducing the static friction coefficient that the mold imparts to the packaging material, and making the packaging material less susceptible to breakage or cracks. Therefore, the electrical storage device packaging material has excellent moldability. Furthermore, after the molding process for the electrical storage device packaging material is completed, when the electrical storage device packaging material is placed in an environment of 40°C or higher, the thermally adhesive resin layer takes in the lubricant from the lubricant layer, and the amount of the lubricant layer increases to 10 mg / m. ２ For this reason, for example, after placing the exterior material in an environment of 40°C or higher, if a battery cell of an electricity storage device is placed between two exterior materials with the lubricant layer facing the battery cell side and the battery cell is pressed via the exterior material, the lubricant contained in the lubricant layer will already be incorporated into the heat-sealable resin layer, and the amount of the lubricant layer will be 10 mg / m or less. ２ Since the static friction coefficient of the exterior material relative to the battery cell is large, it is possible to suppress the exterior material from slipping relative to the battery cell.

[0012] In the above-described electrical storage device packaging material, the heat-sealable resin layer preferably includes a sealant layer, and the sealant layer preferably contains less than 200 ppm by mass of lubricant. In this case, when the electrical storage device packaging material is placed in an environment of 40°C or higher, the sealant layer can effectively absorb the lubricant from the lubricant layer. Therefore, for example, after placing the packaging material in an environment of 40°C or higher, placing a battery cell of the electrical storage device between two packaging materials with the lubricant layer facing the battery cell and applying pressure to the battery cell via the packaging material increases the static friction coefficient of the packaging material relative to the battery cell, thereby more sufficiently suppressing slippage of the packaging material relative to the battery cell.

[0013] In the packaging material for a power storage device, the heat-sealable resin layer preferably includes a sealant layer, and the sealant layer preferably includes a polyolefin resin. In this case, the heat-sealable resin layer of the heat-sealable resin layer has improved heat-sealability and is likely to have reduced moisture permeability, allowing the packaging material to have high heat-sealability and barrier properties.

[0014] In the packaging material for a power storage device, the lubricant contained in the lubricant layer may be a fatty acid amide.

[0015] In the exterior packaging material for a power storage device, the lubricant layer is preferably obtained by coating a composition containing the lubricant. Since the lubricant layer is obtained by coating a composition containing the lubricant, the amount of the lubricant layer is easily controlled. For this reason, the amount of the lubricant layer is set to 10 mg / m, which exhibits excellent moldability. ２ In addition, since the lubricant layer is obtained by coating a composition containing a lubricant, the amount of the lubricant layer can be set to be equal to or less than the amount of lubricant that can be incorporated into the heat-sealable resin layer.

[0016] In the above-mentioned casing material for a power storage device, the surface roughness Sa of the surface of the heat-sealable resin layer on the side of the lubricant layer is preferably 1.0 μm or less. The surface roughness Sa of the surface of the heat-sealable resin layer on the side of the lubricant layer also affects the ease of slippage of a mold. If the surface roughness Sa of the surface of the heat-sealable resin layer on the side of the lubricant layer is 1.0 μm or less, the contact area between the casing material and the battery cell can be increased after the lubricant contained in the lubricant layer is incorporated into the heat-sealable resin layer, making it less likely that the casing material will slip relative to the battery cell.

[0017] The packaging material for a power storage device may further include an adhesive layer between the base material layer and the barrier layer.

[0018] In the above-mentioned packaging material for a power storage device, it is preferable that the static friction coefficient at 60° C. on the surface of the lubricant layer of the packaging material is 0.75 or more.

[0019] In this case, when the battery cells of the energy storage device are placed between two exterior materials with the lubricant layer facing the battery cells and the battery cells are pressurized via the exterior materials, even when the energy storage device is operated and the battery cells heat up to 60°C or higher, the static friction coefficient of the exterior materials against the battery cells becomes larger, and slippage of the exterior materials against the battery cells can be more sufficiently suppressed. This makes it possible to make the battery cells less likely to become misaligned with the exterior materials, particularly when the battery cells become larger and their own weight increases.

[0020] In the above-mentioned packaging material for a power storage device, it is preferable that the static friction coefficient at 23° C. on the surface of the lubricant layer of the packaging material is 0.4 or less.

[0021] In this case, if the static friction coefficient at 23°C on the surface of the lubricant layer of the packaging material is 0.4 or less, when a mold is used to form recesses in the packaging material from the lubricant layer side, the mold easily slides against the lubricant layer, reducing the static friction coefficient that the mold imparts to the packaging material and making it less likely that the packaging material will break or crack.As a result, the packaging material for an electricity storage device has even better moldability.

[0022] In the packaging material for an electricity storage device, the electricity storage device may be an all-solid-state battery.

[0023] Another aspect of the present disclosure provides an electricity storage device including a battery cell and an outer container for accommodating the battery cell, the outer container being obtained using the above-described exterior packaging material for an electricity storage device. According to this electricity storage device, the exterior packaging material has excellent formability, making it less susceptible to breakage or cracks. This makes it possible to suppress the intrusion of moisture into the exterior packaging. Furthermore, even if the battery cell generates heat during operation of the electricity storage device, causing the exterior packaging material to reach a high temperature of 40°C or higher, the lubricant layer is incorporated into the heat-sealable resin layer, and the amount of the lubricant layer is 10 mg / m ２ Since the static friction coefficient of the exterior material relative to the battery cell is large, it is possible to suppress the exterior material from slipping relative to the battery cell.

[0024] The power storage device may be an all-solid-state battery.

[0025] According to the present disclosure, it is possible to provide an exterior material for a power storage device that has excellent formability and can suppress slippage relative to a battery cell even when the battery cell of the power storage device is placed in an environment of 40°C or higher while being pressurized, and a power storage device using the same.

[0026] Fig. 1 is a schematic cross-sectional view of an exterior packaging material for an electricity storage device according to an embodiment of the present disclosure. Fig. 2 is a schematic cross-sectional view of an exterior packaging material for an electricity storage device according to an embodiment of the present disclosure. Fig. 3 is a perspective view of an electricity storage device according to an embodiment of the present disclosure. Fig. 4 is a plan view of a molded body used in Examples and Comparative Examples.

[0027] 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.

[0028] [Sheathing material for an electric storage device] Fig. 1 is a cross-sectional view schematically showing one embodiment of the sheathing material for an electric storage device according to the present disclosure. As shown in Fig. 1, the sheathing material (sheathing material for an electric storage device) 10 of this embodiment is a laminate including, in this order, a base material layer 11, an outer adhesive layer 12a, a barrier layer 17 including a metal foil layer 13, an inner adhesive layer 12b, a sealant layer 16 as a heat-sealable resin layer, and a lubricant layer 18 including a lubricant.

[0029] The barrier layer 17 may further include a first corrosion prevention treatment layer 14a and a second corrosion prevention treatment layer 14b on both sides of the metal foil layer 13. The first corrosion prevention treatment layer 14a is provided on the surface of the metal foil layer 13 facing the base material layer 11, and the second corrosion prevention treatment layer 14b is provided on the surface of the metal foil layer 13 facing the sealant layer 16. Note that the barrier layer 17 may be provided with only one of the first corrosion prevention treatment layer 14a and the second corrosion prevention treatment layer 14b, or may not be provided with any corrosion prevention treatment layer.

[0030] When the exterior packaging material 10 is placed in an environment of 40° C. or higher, the sealant layer 16 takes in the lubricant from the lubricant layer 18, and the amount of the lubricant layer 18 is 10 mg / m ２ It is possible to do the following:

[0031] Each layer constituting the exterior packaging material 10 will be described in more detail below.

[0032] <Base Material Layer> The base material layer 11 provides heat resistance in a sealing step when manufacturing an electricity storage device and plays a role in suppressing the occurrence of pinholes that may occur during molding or 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, insulation properties, etc.

[0033] The base layer 11 is preferably a resin film formed from 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.

[0034] Among these resins, polyester resins and polyamide resins are preferred for the substrate 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, and nylon 12. Among polyester resins and polyamide resins, polyester resins are particularly preferred for the substrate layer 11. Polyester resins have excellent heat resistance, chemical resistance, and moldability. Therefore, even when sealing the exterior packaging material 10 to form an exterior container, the substrate layer 11 is less likely to melt. Furthermore, even when the exterior packaging material 10 is used in a high-temperature environment (e.g., 120°C), the substrate layer 11 is less likely to yellow. Furthermore, the substrate layer 11 is less likely to dissolve when exposed to chemicals, and is less likely to break when molded into the exterior packaging material 10.

[0035] The substrate layer 11 may be either a stretched or unstretched film, or a coating film. The substrate layer 11 may be a single layer or a multilayer, and in the case of a multilayer, layers made of different resins may be used in combination. When the substrate layer 11 is a film, the substrate layer 11 may be a layer obtained by co-extruding multiple resin layers, or a layer obtained by laminating multiple resin layers via an adhesive. When the substrate layer 11 has a coating film, the substrate layer 11 may be a layer coated with the same number of coating films as the number of laminations, or a laminate combining a film and a coating film may also be used.

[0036] When the substrate layer 11 is a stretched film, the substrate layer 11 may be a uniaxially stretched film or a biaxially stretched film, but is preferably a biaxially stretched film. In this case, since the substrate layer 11 has high strength in two orthogonal directions, the substrate layer 11 is less likely to break even when molded into the packaging material 10. In other words, the packaging material 10 has excellent formability. Examples of stretching methods for biaxially stretched films include sequential biaxial stretching, tubular biaxial stretching, and simultaneous biaxial stretching. From the viewpoint of obtaining better deep draw formability, the biaxially stretched film is preferably one stretched by tubular biaxial stretching.

[0037] The base layer 11 may be a single-layer film made of one type of resin film, or may be a laminated film made of two or more types of resin films.

[0038] The thickness of the substrate layer 11 is preferably 6 to 50 μm, and more preferably 10 to 30 μm. When the thickness of the substrate layer 11 is 6 μm or more, the pinhole resistance and insulating properties of the packaging material 10 tend to be improved. When the thickness of the substrate layer 11 is 50 μm or less, the total thickness of the packaging material 10 can be reduced.

[0039] The melting point of the base material layer 11 is not particularly limited, but in order to suppress deformation of the base material layer 11 during sealing, it is preferably higher than the melting point of the sealant layer 16. Furthermore, the melting point of the base material layer 11 is more preferably higher than the melting point of the sealant layer 16 by 30° C. or more.

[0040] <Outer adhesive layer> The outer adhesive layer 12a is a layer that bonds the base material layer 11 and the barrier layer 17. Specific examples of materials that constitute the outer adhesive layer 12a include polyurethane resins obtained by reacting a base material such as polyester polyol, polyether polyol, acrylic polyol, or carbonate polyol with a curing agent such as a difunctional or higher isocyanate compound (polyfunctional isocyanate compound). Among polyurethane resins, polyester urethane resins obtained using a polyester polyol and a difunctional or higher isocyanate compound are preferred because they are more likely to prevent the outer layer (base material layer 11) from lifting under high-temperature conditions.

[0041] 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 exterior packaging material 10.

[0042] Depending on the performance required of the adhesive, various other additives and stabilizers may be blended into the polyurethane resin described above.

[0043] In the polyurethane-based adhesive used to form the outer adhesive layer 12a containing the above-mentioned polyurethane resin, the ratio (NCO / OH) of the number of isocyanato groups contained in the polyfunctional isocyanate compound to the number of hydroxyl groups contained in the polyol may be 2 to 60, 5 to 50, or 10 to 40. When this ratio is 2 or more, the adhesive strength between the base material layer 11 and the metal foil layer 13 can be further improved in a high-temperature environment (e.g., 150°C), and the lifting of the base material layer 11 from the metal foil layer 13 in a high-temperature environment can be more easily suppressed. When the ratio is 60 or less, excessive unreacted hydroxyl groups can be prevented from remaining, and the adhesive strength between the base material layer 11 and the barrier layer 17 can be more easily improved in both room temperature and high-temperature environments. The heat resistance of the cured product of the polyurethane-based adhesive (outer adhesive layer 12a) is improved by units such as urea and biuret, which are generated by the reaction of trace amounts of water contained in the air or the adhesive with the polyfunctional isocyanate compound. Therefore, the more the polyfunctional isocyanate compound, the more these units there are, which in turn increases Tg and tends to improve heat resistance. Furthermore, among polyfunctional isocyanate compounds, aliphatic (alicyclic) polyfunctional isocyanate compounds in particular have excellent heat resistance, and can further improve the adhesion between the base material layer 11 and the barrier layer 17 in a high-temperature environment.

[0044] The thickness of the outer adhesive layer 12a is not particularly limited, but is preferably 1 to 10 μm, and more preferably 3 to 7 μm, from the viewpoint of obtaining the desired adhesive strength, conformability, processability, etc. If the thickness of the outer adhesive layer 12a is 1 μm or more, high adhesive strength is likely to be obtained and stress relaxation of shear forces generated during thermal expansion of the base material layer 11 and the metal foil layer 13 in a high-temperature environment is facilitated. On the other hand, if the thickness of the outer adhesive layer 12a is 10 μm or less, the moldability of the packaging material 10 can be further improved and lifting of the outer layer (base material layer 11) in a high-temperature environment is more likely to be suppressed.

[0045] <Barrier Layer> The metal foil layer 13 included in the barrier layer 17 has water vapor barrier properties that prevent moisture from penetrating into the interior of the energy storage device. The metal foil layer 13 may also have extensibility for deep drawing. Various metal foils, such as aluminum, stainless steel, and copper, can be used as the metal foil layer 13. The metal foil layer 13 does not significantly soften at 120°C and has a significant effect of suppressing elongation in high-temperature environments. Among these, aluminum foil is more preferable. Aluminum foil has high barrier properties, good formability and flexibility, and is lightweight. This can improve the barrier properties of the packaging material 10. Furthermore, even when the packaging material 10 is molded, the metal foil layer 13 is less likely to break, thereby preventing a decrease in the barrier properties of the packaging material 10. Furthermore, the improved flexibility of the packaging material 10 allows the packaging material 10 to conform to the shape of a battery cell even when the battery cell is housed in an exterior container formed using the packaging material 10. Furthermore, because the exterior packaging material 10 is lightweight, it is also possible to increase the volumetric energy density of an electricity storage device that includes the exterior packaging material 10. Furthermore, since the aluminum foil does not need to be thinned in order to provide good conformability to the shape of the battery cell, it is possible to prevent the remaining thickness of the metal foil layer 13 from becoming small after deep drawing of the exterior packaging material 10.

[0046] As the aluminum foil, soft aluminum foil that has been annealed can be preferably used because it can impart the desired ductility during molding. However, it is more preferable to use aluminum foil containing iron for the purpose of imparting further pinhole resistance and ductility during molding. The iron content in the aluminum foil is preferably 0.1 to 9.0 mass%, more preferably 0.5 to 2.0 mass%, based on 100 mass% of the aluminum foil. By having an iron content of 0.1 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 mass% or less, an exterior packaging material 10 having better flexibility can be obtained. As the aluminum foil, untreated aluminum foil may be used, 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.

[0047] The thickness of the metal foil layer 13 is not particularly limited, but in consideration of barrier properties, pinhole resistance, and processability, it is preferably 9 to 200 μm, and more preferably 15 to 100 μm.

[0048] <First Anti-Corrosion Treatment Layer and Second Anti-Corrosion Treatment Layer> The first anti-corrosion treatment layer 14a and the second anti-corrosion treatment layer 14b are layers provided to prevent corrosion of the metal foil (metal foil layer) constituting the metal foil layer 13. The first anti-corrosion treatment layer 14a serves to increase the adhesion between the metal foil layer 13 and the outer adhesive layer 12a. The second anti-corrosion treatment layer 14b serves to increase the adhesion between the metal foil layer 13 and the inner adhesive layer 12b. The first anti-corrosion treatment layer 14a and the second anti-corrosion treatment layer 14b may be layers of the same configuration or layers of different configurations. The first and second anti-corrosion treatment layers 14a, 14b (hereinafter simply referred to as "anti-corrosion treatment layers 14a, 14b") may be formed, for example, by degreasing, hydrothermal conversion treatment, anodizing, chemical conversion treatment, or a combination of these treatments.

[0049] Examples of degreasing treatments include acid degreasing and alkaline degreasing. Examples of acid degreasing include a method using an inorganic acid such as sulfuric acid, nitric acid, hydrochloric acid, or hydrofluoric acid, either alone or in combination. Furthermore, by using an acid degreasing agent prepared by dissolving a fluorine-containing compound such as monosodium ammonium difluoride in the inorganic acid, not only can the aluminum be degreased, but also a passive aluminum fluoride can be formed, particularly when an aluminum foil is used for the metal foil layer 13. Therefore, using an acid degreasing agent prepared by dissolving a fluorine-containing compound such as monosodium ammonium difluoride in the inorganic acid is effective in terms of corrosion resistance. Examples of alkaline degreasing include a method using sodium hydroxide or the like.

[0050] An example of the hydrothermal modification treatment is boehmite treatment, in which aluminum foil is immersed in boiling water containing triethanolamine.

[0051] An example of the anodizing treatment is alumite treatment.

[0052] Examples of chemical conversion treatments include immersion-type chemical conversion treatments and paint-type chemical conversion treatments. Examples of immersion-type chemical conversion treatments 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 mixed phases of these. On the other hand, examples of paint-type chemical conversion treatments include a method in which a coating agent having corrosion prevention properties is applied to the metal foil layer 13.

[0053] 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 above-mentioned degreasing treatment 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 metal foil layer 13, there is no need to perform a degreasing treatment again when forming the corrosion prevention treatment layers 14a, 14b.

[0054] 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.

[0055] Furthermore, among the above treatments, particularly hydrothermal conversion treatment and anodizing treatment, the aluminum foil surface is dissolved by a treatment agent to form aluminum compounds (boehmite, alumite) with excellent corrosion resistance. Therefore, since a co-continuous structure is formed from the metal foil layer 13 using aluminum foil to the corrosion prevention treatment layers 14a, 14b, the above 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 this method is a method using 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 prevention effect (inhibitor effect) and is environmentally friendly. By using this method, it is possible to impart corrosion prevention effects to metal foils such as aluminum foil using a general coating method.

[0056] Examples of the rare earth element oxide sol include sols using various solvents such as aqueous solvents, alcoholic solvents, hydrocarbon solvents, ketone solvents, ester solvents, and ether solvents. Of these, aqueous sols (sols using aqueous solvents) are preferred.

[0057] In order to stabilize the dispersion of the rare earth element oxide sol, inorganic acids such as nitric acid, hydrochloric acid, 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. Of these dispersion stabilizers, phosphoric acid in particular is expected to have the following effects in the packaging material 10: (1) Stabilization of the dispersion of the sol (2) Improvement of the adhesion between the metal foil layer 13 and the corrosion prevention treatment layers 14a, 14b by utilizing the aluminum chelating ability of phosphoric acid (3) Improvement of the cohesion of the corrosion prevention treatment layers 14a, 14b (oxide layers) due to the tendency of phosphoric acid to undergo dehydration condensation even at low temperatures

[0058] 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.

[0059] Furthermore, 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 containing a resin binder (such as aminophenol) mixed with phosphoric acid and a chromium compound, 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 in which a rare earth element oxide sol and a polycationic polymer or a polyanionic polymer are preliminarily mixed into a one-component solution can be used to obtain a layer that combines corrosion prevention functionality and adhesion.

[0060] The mass per unit area of ​​the corrosion prevention treatment layers 14a and 14b is 0.005 to 0.200 g / m2, whether the layer has a multi-layer structure or a single-layer structure. ２ is preferred, and 0.010 to 0.100 g / m ２ It is more preferable that the mass per unit area is 0.005 g / m 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 metal foil layer 13. ２ Even if the thickness exceeds 100 μm, 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 14 a and 14 b can be calculated from their specific gravity.

[0061] From the viewpoint of making it easier to maintain adhesion between the sealant layer 16 and the metal foil layer 13, the corrosion prevention treatment layers 14a, 14b may be in an embodiment containing, for example, cerium oxide, 1 to 100 parts by mass of phosphoric acid or a phosphate salt per 100 parts by mass of the cerium oxide, and a cationic polymer, or may be in an embodiment formed by subjecting the metal foil layer 13 to a chemical conversion treatment, or may be in an embodiment formed by subjecting the metal foil layer 13 to a chemical conversion treatment and containing a cationic polymer.

[0062] <Inner adhesive layer> The inner adhesive layer 12b is a layer that bonds the metal foil layer 13, on which the second corrosion prevention treatment layer 14b is formed, to the sealant layer 16. For the inner adhesive layer 12b, a general adhesive for bonding a metal foil layer to the sealant layer 16 can be used, and for example, the same adhesive as the outer adhesive layer 12a described above can be used.

[0063] The thickness of the inner adhesive layer 12b is not particularly limited, but is preferably 1 to 10 μm, more preferably 3 to 7 μm, from the viewpoint of obtaining the desired adhesive strength and processability.

[0064] <Sealant Layer> The sealant layer 16 is a layer that imparts heat-sealing sealability to the exterior packaging material 10. Examples of the sealant layer 16 include resin films containing a base resin. Examples of base resins include polyolefin-based resins and polyester-based resins. These may be used alone or in combination of two or more. Polyolefin-based resins and polyester-based resins not only have excellent heat-sealing properties but also have a certain degree of flexibility. Therefore, when the sealant layer 16 contains at least one of a polyolefin-based resin and a polyester-based resin, the exterior packaging material 10 is less likely to curl even if the sealant layer 16 is thicker than the base material layer 11. In particular, it is preferable that the sealant layer 16 contains a polyolefin resin. In this case, not only is the heat-sealing property of the sealant layer 16 improved, but moisture permeability is also likely to be reduced, allowing the exterior packaging material 10 to have high heat-sealing properties and barrier properties.

[0065] Examples of polyolefin-based resins include low-, medium-, or high-density polyethylene, ethylene-α-olefin copolymer, homopolypropylene, block polypropylene, random polypropylene, and propylene-α-olefin copolymer. Among these, the polyolefin-based resin is preferably composed of at least one of homopolypropylene and block polypropylene. Compared to random polypropylene, homopolypropylene and block polypropylene not only have superior heat resistance but also superior hardness. Therefore, when the sealant layer 16 is composed of at least one of homopolypropylene and block polypropylene, the base material layer 11 can be made thicker and harder. As a result, the exterior packaging material 10 can have excellent moldability and can also be prevented from curling.

[0066] Examples of polyester resins include polyethylene terephthalate (PET) resin, polybutylene terephthalate (PBT) resin, polyethylene naphthalate (PEN) resin, polybutylene naphthalate (PBN) resin, and copolymers thereof.

[0067] The sealant layer 16 may contain a polyolefin-based elastomer. The polyolefin-based elastomer may be compatible or incompatible with the base resin described above, and may contain both a compatible polyolefin-based elastomer that is compatible with the base resin and an incompatible polyolefin-based elastomer that is incompatible with the base resin. "Compatible" means that the elastomer disperses in the base resin with a dispersed phase size of 1 nm or more and less than 500 nm. "Incompatible" means that the elastomer disperses in the base resin with a dispersed phase size of 500 nm or more and less than 20 μm.

[0068] When the base resin is a polypropylene resin, the compatible polyolefin elastomer may be, for example, a propylene-butene-1 random copolymer, and the incompatible polyolefin elastomer may be, for example, an ethylene-butene-1 random copolymer. The polyolefin elastomers may be used alone or in combination of two or more.

[0069] The sealant layer 16 may also contain additives such as slip agents, antioxidants, light stabilizers, and flame retardants. The content of these additives is preferably 5 parts by mass or less, assuming the total mass of the sealant layer 16 to be 100 parts by mass. The sealant layer 16 may also contain a lubricant as an additive. The lubricant is not particularly limited, but preferred examples include amide-based lubricants and silicone oils. Specific examples of amide-based lubricants include fatty acid amides such as saturated fatty acid amides and unsaturated fatty acid amides; and fatty acid bisamides such as saturated fatty acid bisamides and unsaturated fatty acid bisamides. Among these, fatty acid amides are preferred from the viewpoint of film-forming properties of the sealant layer 16. Specific examples of saturated fatty acid amides include lauric acid amide, palmitic acid amide, and stearic acid amide. Specific examples of unsaturated fatty acid amides include oleic acid amide and erucic acid amide. Specific examples of saturated fatty acid bisamides include methylene bisstearic acid amide, ethylene biscapric acid amide, ethylene bislauric acid amide, and ethylene bisstearic acid amide. Specific examples of unsaturated fatty acid bisamides include ethylene bis-erucic acid amide and ethylene bis-oleic acid amide. The boiling point of the lubricant is not particularly limited, but is preferably 180°C or higher. In this case, even if the exterior material 10 is placed in a high-temperature environment of 150°C or higher, volatilization of the lubricant is suppressed. Examples of such lubricants include the fatty acid amides and fatty acid bisamides mentioned above. One type of lubricant may be used alone, or two or more types may be used in combination. The content of the lubricant in the sealant layer 16 is determined such that, when the exterior material 10 is placed in an environment of 40°C or higher, the sealant layer 16 takes in the lubricant from the lubricant layer 18, and the amount of the lubricant layer 18 is 10 mg / m ２The amount of lubricant in the sealant layer 16 is not particularly limited as long as it allows the sealant layer 16 to absorb the lubricant from the lubricant layer 18 when the exterior packaging material 10 is placed in an environment of 40°C or higher, but the lower the lubricant content in the sealant layer 16, the more easily the sealant layer 16 will absorb the lubricant from the lubricant layer 18 when the exterior packaging material 10 is placed in an environment of 40°C or higher. Note that the amount of lubricant layer 18 when the exterior packaging material 10 is placed in an environment of 40°C or higher refers to the amount of lubricant layer 18 when the exterior packaging material 10 is placed in an environment of 40°C or higher for two weeks (336 hours). The lubricant content in the sealant layer 16 may be 1000 ppm by mass or less, 500 ppm by mass or less, or less than 200 ppm by mass, but is preferably less than 200 ppm by mass. In this case, when the exterior packaging material 10 is placed in an environment of 40°C or higher, the sealant layer 16 will be able to effectively absorb the lubricant from the lubricant layer 18. Therefore, for example, after placing the exterior packaging material 10 in an environment of 40°C or higher, a battery cell of an energy storage device is placed between two exterior packaging materials 10 with the lubricant layer 18 facing the battery cell side, and pressure is applied to the battery cell via the exterior packaging material 10. This increases the static friction coefficient of the exterior packaging material 10 against the battery cell, making it possible to more sufficiently suppress sliding of the exterior packaging material 10 against the battery cell. The lubricant content in the sealant layer 16 is preferably 150 ppm by mass or less, more preferably 120 ppm by mass or less, even more preferably 100 ppm by mass or less, and particularly preferably 50 ppm by mass or less. The lubricant content in the sealant layer 16 may be 0 ppm by mass, but from the viewpoint of processability, it is preferably 10 ppm by mass or more, more preferably 20 ppm by mass or more, and particularly preferably 50 ppm by mass or more. The surface roughness Sa of the surface of the sealant layer 16 facing the lubricant layer 18 is not particularly limited and may be preferably less than 1.5 μm or 1.0 μm or less, but is preferably 1.0 μm or less. The surface roughness Sa of the surface of the sealant layer 16 facing the lubricant layer 18 also affects the ease of slippage of the mold. If the surface roughness Sa of the surface of the sealant layer 16 facing the lubricant layer 18 is 1.0 μm or less, the contact area between the exterior packaging material 10 and the battery cell can be increased after the lubricant contained in the lubricant layer 18 is absorbed into the sealant layer 16, making it less likely that the exterior packaging material 10 will slip relative to the battery cell.The surface roughness Sa of the surface of the sealant layer 16 facing the lubricant layer 18 is preferably less than 0.7 μm, more preferably 0.50 μm or less, and particularly preferably 0.30 μm or less. From the viewpoint of formability, the surface roughness Sa of the surface of the sealant layer 16 facing the lubricant layer 18 is preferably 0.12 μm or more, and more preferably 0.15 μm or more.

[0070] The sealant layer 16 may be either a single-layer film or a multilayer film, and may be selected depending on the required function. When the sealant layer 16 is a multilayer film, the layers may be laminated together by coextrusion or by dry lamination.

[0071] The thickness of the sealant layer 16 is not particularly limited, but from the viewpoint of achieving both a thin film and improved heat seal strength in a high-temperature environment, it is preferably in the range of 5 to 100 μm, more preferably in the range of 10 to 100 μm, and even more preferably in the range of 20 to 80 μm.

[0072] <Lubricant Layer> The lubricant layer 18 contains a lubricant. The lubricant is not particularly limited, but preferred examples include amide-based lubricants and silicone oils. Specific examples of amide-based lubricants include fatty acid amides such as saturated fatty acid amides and unsaturated fatty acid amides; and fatty acid bisamides such as saturated fatty acid bisamides and unsaturated fatty acid bisamides. Of these, fatty acid amides are preferred from the viewpoint of processability.

[0073] Specific examples of saturated fatty acid amides include lauric acid amide, palmitic acid amide, and stearic acid amide. Specific examples of unsaturated fatty acid amides include oleic acid amide and erucic acid amide. Specific examples of saturated fatty acid bisamides include methylene bisstearic acid amide, ethylene biscapric acid amide, ethylene bislauric acid amide, and ethylene bisstearic acid amide. Specific examples of unsaturated fatty acid bisamides include ethylene biserucic acid amide and ethylene bisoleic acid amide. The lubricants may be used alone or in combination of two or more.

[0074] The boiling point of the lubricant is not particularly limited, but is preferably 180° C. or higher. In this case, volatilization of the lubricant is suppressed even when the exterior packaging material 10 is placed in a high-temperature environment of 150° C. or higher. Examples of such lubricants include the fatty acid amides and fatty acid bisamides described above.

[0075] The lubricant may be the same as or different from the lubricant contained in the sealant layer 16, but is preferably the same. The behavior of the lubricant in the lubricant layer 18, such as being taken up into the sealant layer 16 or bleed-out from the sealant layer 16, differs depending on the type of lubricant in the sealant layer 16. When the lubricant in the lubricant layer 18 is the same as the lubricant contained in the sealant layer 16, this behavior can be more easily controlled.

[0076] The amount of the lubricant layer 18 is 10 mg / m ２ Even if it is less than 10 mg / m ２ It may be more, but not more than 10 mg / m ２ The amount of the lubricant layer 18 is preferably 10 mg / m ２ By increasing the amount of lubricant layer 18, when a recess is formed in exterior packaging material 10 from the side of lubricant layer 18 using a mold, the mold slides more easily on lubricant layer 18, the static friction coefficient that the mold exerts on exterior packaging material 10 is reduced, and breakage or cracking is less likely to occur in exterior packaging material 10. The amount of lubricant layer 18 is set so that when exterior packaging material 10 is placed in an environment of 40°C or higher, the amount of lubricant layer 18 is 10 mg / m ２ The amount of the lubricant layer 18 is preferably 15 mg / m from the viewpoint of moldability. ２ More preferably, it is 20 mg / m or more. ２ More preferably, it is 25 mg / m ２ The amount of the lubricant layer 18 is preferably 40 mg / m from the viewpoint of preventing slippage of the battery cell after molding. ２ More preferably, it is 30 mg / m or less. ２ The following is the result.

[0077] The lubricant layer 18 is preferably obtained by coating a composition containing a lubricant. Since the lubricant layer 18 is obtained by coating a composition containing a lubricant, the amount of the lubricant layer 18 is easy to control. For this reason, the amount of the lubricant layer 18 is set to 10 mg / m, which exhibits excellent moldability. ２ Furthermore, since the lubricant layer 18 is obtained by coating a composition containing a lubricant, the amount of the lubricant layer 18 can be equal to or less than the amount of lubricant that can be incorporated into the sealant layer 16.

[0078] The static friction coefficient at 60°C on the surface of the lubricant layer 18 of the exterior material 10 is not particularly limited, but is preferably 0.75 or greater. In this case, when a battery cell of an energy storage device is placed between two exterior materials 10 with the lubricant layer 18 facing the battery cell and pressure is applied to the battery cell via the exterior material 10, when the energy storage device is operated and the battery cell heats up to 60°C or greater, the static friction coefficient of the exterior material 10 relative to the battery cell increases, thereby more sufficiently suppressing slippage of the exterior material 10 relative to the battery cell. Therefore, particularly when the battery cell becomes larger and its mass increases, it is possible to prevent the battery cell from shifting position relative to the exterior material 10. The static friction coefficient at 60°C is more preferably 0.80 or greater, and particularly preferably 0.85 or greater. The static friction coefficient at 60°C may be 1.3 or less. The static friction coefficient is measured using the inclination method in accordance with JIS P8147. Specifically, using a friction coefficient measuring device (product name "AN-S2", manufactured by Toyo Seiki Seisakusho), a laminate of exterior material 10 and sled (dimensions: 60 mm x 100 mm, mass: 1000 g) is placed on an inclined plate with exterior material 10 facing the inclined plate, and the inclined plate is tilted at a speed of 1.5° / s, and the static friction coefficient is calculated from the maximum static friction force and normal force when exterior material 10 starts to slide.

[0079] The static friction coefficient at 23°C on the surface of lubricant layer 18 of packaging material 10 is not particularly limited, but is preferably 0.4 or less. In this case, if the static friction coefficient at 23°C on the surface of lubricant layer 18 of packaging material 10 is 0.4 or less, when a recess is formed in packaging material 10 from the lubricant layer 18 side using a mold, the mold easily slides against lubricant layer 18, reducing the static friction coefficient that the mold imparts to packaging material 10, making it less likely that breaks or cracks will occur in packaging material 10. Therefore, packaging material 10 has better moldability. The static friction coefficient at 23°C is more preferably 0.2 or less, and particularly preferably 0.15 or less. The static friction coefficient at 23°C is preferably 0.08 or more, and more preferably 0.09 or more. A static friction coefficient of 0.08 or more at 23°C improves the handleability of packaging material 10 during the manufacture of an electricity storage device. That is, when the exterior packaging material 10 is transported by hand or machine before or after molding of the exterior packaging material 10, the exterior packaging material 10 becomes less slippery and easier to handle.

[0080] The above has described in detail a preferred embodiment of the exterior packaging material for a power storage device of the present embodiment, but the present disclosure is not limited to such a specific embodiment, and various modifications and changes are possible within the scope of the gist of the present disclosure as set forth in the claims.

[0081] For example, in FIG. 1, the exterior material 10 includes an outer adhesive layer 12a and an inner adhesive layer 12b, but at least one of these may be omitted.

[0082] Furthermore, while Fig. 1 shows a case in which the barrier layer 17 and the sealant layer 16 are laminated using the inner adhesive layer 12b, the barrier layer 17 and the sealant layer 16 may be laminated using an adhesive resin layer 15, as in the packaging material 20 for a storage battery device shown in Fig. 2. In this case, the laminate of the adhesive resin layer 15 and the sealant layer 16 constitutes a heat-sealable resin layer. Furthermore, in the packaging material 20 for a storage battery device shown in Fig. 2, an inner adhesive layer 12b may be further provided between the barrier layer 17 and the adhesive resin layer 15.

[0083] <Adhesive Resin Layer> The adhesive resin layer 15 is generally configured to contain an adhesive resin composition as a main component and additives as necessary. The adhesive resin composition is not particularly limited, but preferably contains a modified polyolefin resin.

[0084] The modified polyolefin resin is preferably a polyolefin resin graft-modified with an unsaturated carboxylic acid derivative derived from an unsaturated carboxylic acid, or an acid anhydride or ester thereof.

[0085] Examples of polyolefin resins include low density polyethylene, medium density polyethylene, high density polyethylene, ethylene-α-olefin copolymer, homopolypropylene, block polypropylene, random polypropylene, and propylene-α-olefin copolymer.

[0086] The modified polyolefin resin is preferably a polyolefin resin modified with maleic anhydride. Suitable modified polyolefin resins include, for example, "Admer" manufactured by Mitsui Chemicals, Inc. and "Modic" manufactured by Mitsubishi Chemical Corporation. Such modified polyolefin resins have excellent reactivity with various metals and polymers having various functional groups, and this reactivity can be utilized to impart adhesion to the adhesive resin layer 15. Furthermore, the adhesive resin layer 15 may contain various additives, such as compatible and incompatible elastomers, flame retardants, slip agents, antiblocking agents, antioxidants, light stabilizers, and tackifiers, as needed.

[0087] The thickness of the adhesive resin layer 15 is not particularly limited, but is preferably the same as or smaller than that of the sealant layer 16 from the viewpoint of stress relaxation and moisture permeation.

[0088] Furthermore, in the exterior packaging material 20 for a storage battery device, the total thickness of the adhesive resin layer 15 and the sealant layer 16 is preferably in the range of 5 to 100 μm, more preferably in the range of 20 to 80 μm, from the viewpoint of achieving both a thin film and improved heat seal strength in a high-temperature environment.

[0089] [Method of Manufacturing the Sheathing Material] Next, an example of a method of manufacturing the sheathing material 10 shown in Fig. 1 will be described. Note that the method of manufacturing the sheathing material 10 is not limited to the following method.

[0090] The manufacturing method of the exterior packaging material 10 of this embodiment is generally composed of the steps of providing corrosion prevention treatment layers 14a, 14b on the metal foil layer 13 to form the barrier layer 17, bonding the base material layer 11 and the barrier layer 17 together using the outer adhesive layer 12a, further laminating the sealant layer 16 via the inner adhesive layer 12b to produce a laminate, and, if necessary, aging the obtained laminate, and forming a lubricant layer 18 on the sealant layer 16 of the laminate.

[0091] (Barrier Layer Forming Process) This process is a process of forming the corrosion prevention treatment layers 14a and 14b on the metal foil layer 13 to form the barrier layer 17. As described above, examples of the method for forming the barrier layer 17 include subjecting the metal foil layer 13 to degreasing treatment, hydrothermal treatment, anodizing treatment, or chemical conversion treatment, or applying a coating agent having corrosion prevention properties.

[0092] 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 (metal foil layer 13 side) may be applied to the metal foil 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.

[0093] 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.

[0094] 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.

[0095] As described above, the various treatments may be performed on either one or both sides of the metal foil, but in the case of one-side treatment, it is preferable to perform the treatment only on the side on which the sealant layer 16 is laminated. If desired, the above treatments may also be performed on the surface of the base layer 11.

[0096] The coating amount of the coating agent for forming the first layer and the second layer is 0.005 to 0.200 g / m ２ is preferred, and 0.010 to 0.100 g / m ２ is more preferred.

[0097] If dry curing is required, the dry curing can be carried out at a temperature of the base material (metal foil 13) in the range of 60 to 300° C. depending on the drying conditions of the corrosion prevention treatment layers 14a and 14b used.

[0098] (Step of bonding substrate layer and barrier layer) This step is a step of bonding the barrier layer 17 and the substrate layer 11 via the outer adhesive layer 12a. As a bonding method, techniques such as dry lamination, non-solvent lamination, and wet lamination are used, and the two are bonded together using the material that constitutes the outer adhesive layer 12a described above. The outer adhesive layer 12a is applied in a dry coating amount of 1 to 10 g / m ２ in the range of 2 to 7 g / m ２ It is set within the range.

[0099] Specific examples of materials constituting the outer adhesive layer 12a include polyurethane resins obtained by reacting a base material such as polyester polyol, polyether polyol, acrylic polyol, or carbonate polyol with a bifunctional or higher isocyanate compound (a polyfunctional isocyanate compound). In this case, an aliphatic isocyanate compound is preferably used as the polyfunctional isocyanate compound, and an alicyclic isocyanate compound is more preferably used. In this case, the heat resistance of the outer adhesive layer 12a is further improved, allowing the substrate layer 11 and the barrier layer 17 to maintain adhesion even at temperatures as high as 120°C.

[0100] (Laminating step of inner adhesive layer and sealant layer) This step is a step of bonding the sealant layer 16 via the inner adhesive layer 12b to the second corrosion prevention treatment layer 14b side of the barrier layer 17. Examples of the bonding method include a wet process and dry lamination.

[0101] In the case of a wet process, a solution or dispersion of the adhesive constituting the inner adhesive layer 12b is applied onto the second corrosion prevention treatment layer 14b, the solvent is evaporated at a predetermined temperature to form a dry film, and after the dry film formation, a baking process is performed as necessary. Thereafter, a sealant layer 16 as a heat-sealable resin layer is laminated to produce the exterior material 10. Various coating methods can be used for the coating. The preferred dry coating amount of the inner adhesive layer 12b is the same as that of the outer adhesive layer 12a.

[0102] 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 components of the sealant layer 16. From the viewpoint of productivity, the melt extrusion molding machine can be operated at a processing speed of 80 m / min or more. In this case, when the exterior packaging material 10 is placed in an environment of 40°C or higher, the sealant layer 16 takes in the lubricant from the lubricant layer 18, and the amount of the lubricant layer 18 is increased to 10 mg / m. ２ It is formed so that the following can be achieved.

[0103] (Aging Treatment Step) This step is a step of aging (curing) the laminate. By aging the laminate, it is possible to promote adhesion between the metal foil layer 13, the second corrosion prevention treatment layer 14b, the inner adhesive layer 12b, and the sealant layer 16. The aging treatment can be carried out at a temperature ranging from room temperature to 100°C. The aging time is, for example, 1 to 10 days.

[0104] (Lubricant Layer Forming Step) This step is a step of forming the lubricant layer 18. The lubricant layer 18 can be formed by preparing a composition containing a lubricant and applying this composition to the surface of the sealant layer 16. When the exterior packaging material 10 is placed in an environment of 40°C or higher, the lubricant is absorbed from the lubricant layer 18, and the amount of the lubricant layer 18 is increased to 10 mg / m ２The amount is adjusted so that the following can be achieved.

[0105] In this manner, the exterior packaging material 10 of this embodiment as shown in FIG. 1 can be manufactured.

[0106] Next, a description will be given of an example of a method for manufacturing the exterior packaging material 20 shown in Fig. 2. Note that the method for manufacturing the exterior packaging material 20 is not limited to the following method.

[0107] The manufacturing method of the packaging material 20 of this embodiment is generally configured to include the steps of providing corrosion prevention treatment layers 14a, 14b on the metal foil layer 13 to form the barrier layer 17, bonding the base material layer 11 and the barrier layer 17 together using the outer layer adhesive layer 12a, further laminating a heat-sealable resin layer consisting of an adhesive resin layer 15 and a sealant layer 16 to prepare a laminate, and, if necessary, heat-treating the obtained laminate, and forming a lubricant layer 18 on the sealant layer 16. Note that the steps up to the step of bonding the base material layer 11 and the barrier layer 17 and the step of forming the lubricant layer 18 on the sealant layer 16 can be performed in the same manner as in the manufacturing method of the packaging material 10 described above.

[0108] (Laminating Process of Adhesive Resin Layer and Sealant Layer) This process is a process of forming an adhesive resin layer 15 and a sealant layer 16 on the second corrosion prevention treatment layer 14b formed in the previous process. Examples of the method include sand lamination of the adhesive resin layer 15 together with the sealant layer 16 using an extrusion laminator. Furthermore, the adhesive resin layer 15 and the sealant layer 16 can also be laminated by a tandem lamination method or a co-extrusion method in which the adhesive resin layer 15 and the sealant layer 16 are extruded. When forming the adhesive resin layer 15 and the sealant layer 16, for example, the respective components are blended so as to satisfy the above-described structures of the adhesive resin layer 15 and the sealant layer 16. The above-described resin composition for forming the sealant layer is used to form the sealant layer 16.

[0109] This step produces a laminate as shown in FIG. 2, in which the layers are stacked in the following order: base material layer 11 / outer adhesive layer 12a / first corrosion prevention treatment layer 14a / metal foil layer 13 / second corrosion prevention treatment layer 14b / thermal fusion resin layer (adhesive resin layer 15 / sealant layer 16).

[0110] The adhesive resin layer 15 may be formed by directly extruding a material obtained by dry-blending the components thereof using an extrusion laminator, or by extruding the granulated material obtained by previously melt-blending the components using a melt-kneading device such as a single-screw extruder, a twin-screw extruder, or a Brabender mixer, using an extrusion laminator.

[0111] The sealant layer 16 may be laminated by directly extruding a material obtained by dry-blending the components of the resin composition for forming the sealant layer using an extrusion laminator. Alternatively, the adhesive resin layer 15 and the sealant layer 16 may be laminated by a tandem lamination method or a coextrusion method in which the adhesive resin layer 15 and the sealant layer 16 are extruded using an extrusion laminator after melt-blending in advance using a melt-kneading device such as a single-screw extruder, a twin-screw extruder, or a Brabender mixer. Alternatively, the adhesive resin layer 15 and the sealant layer 16 may be laminated by a method in which a sealant monolayer is pre-cast as a film using the resin composition for forming the sealant layer, and this film is then sandwich-laminated together with the adhesive resin. 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.

[0112] (Heat Treatment Step) This step is a step of heat treating the laminate. Heat treating the laminate can improve adhesion between the metal foil layer 13, the second corrosion prevention treatment layer 14b, the adhesive resin layer 15, and the sealant layer 16. As a heat treatment method, a method of treating at a temperature at least equal to or higher than the melting point of the adhesive resin layer 15 is preferred.

[0113] In this manner, the exterior packaging material 20 of this embodiment as shown in FIG. 2 can be manufactured.

[0114] [Electricity Storage Device] Next, an embodiment of an electricity storage device according to another aspect of the present disclosure will be described with reference to FIG. 3 . FIG. 3 is a perspective view showing one embodiment of an electricity storage device fabricated using the above-described exterior material. As shown in FIG. 3 , the electricity storage device 50 includes battery cells 52 and an exterior container 54 that houses the battery cells 52. The exterior container 54 is obtained using the above-described exterior material 10. In the exterior material 10, the base material layer 11 is the outermost layer, and the sealant layer 16 is the innermost layer. The exterior container 54 is configured to house the battery cells 52 by folding one laminate film in half and heat-sealing it, or by overlapping and heat-sealing two laminate films, so that the base material layer 11 is on the exterior side of the electricity storage device 50 and the sealant layer 16 is on the interior side of the electricity storage device 50. The electricity storage device 50 may further include two metal terminals (current extraction terminals) 53 for extracting current from the battery cells 52 to the outside. In addition, in the electricity storage device 50 , the outer container 54 may be formed using the outer packaging material 20 instead of the outer packaging material 10 .

[0115] The battery cell 52 has an electrolyte interposed between a positive electrode and a negative electrode. The metal terminal 53 is a current collector that is partially extended to the exterior of the exterior packaging material 10 and is made of a metal foil such as copper foil or aluminum foil. Examples of the negative electrode include a silicon-based negative electrode and a carbon-based negative electrode. The power storage device of the present disclosure is particularly effective when the negative electrode is a silicon-based negative electrode. It is said that when a silicon-based negative electrode absorbs Li during charging, its volume increases by 300 to 400%, making the exterior packaging material of the present disclosure useful.

[0116] According to the electricity storage device 50 of this embodiment, the exterior material 10 has excellent moldability, making it less susceptible to breakage or cracks. This makes it possible to prevent moisture from penetrating into the exterior container 54. Furthermore, even if the battery cells 52 generate heat during operation of the electricity storage device 50 and the exterior material 10 reaches a high temperature of 40°C or higher, the lubricant layer 18 is incorporated into the sealant layer 16, and the amount of lubricant layer 18 is 10 mg / m ２ Since the static friction coefficient of the exterior material 10 relative to the battery cell 52 is large, slippage of the exterior material 10 relative to the battery cell 52 can be suppressed.

[0117] The power storage device 50 of this embodiment may be an all-solid-state battery. When the power storage device 50 is an all-solid-state battery, the power storage device 50 is used in a state in which the battery cells 52 are pressurized via the exterior material 10 of the exterior container 54 in order to improve its performance. Here, in order to maintain the performance of the power storage device 50, it is desirable to suppress slippage between the battery cells 52 and the exterior material 10 even when the power storage device 50 is subjected to vibration. In this regard, the power storage device 50 is particularly useful when it is an all-solid-state battery, because it can suppress slippage of the exterior material 10 relative to the battery cells 52 even when subjected to vibration. A solid electrolyte such as a sulfide-based solid electrolyte is used as the electrolyte of the battery cells 52.

[0118] The power storage device of the present disclosure may be, for example, a power storage device such as a secondary battery, such as a lithium ion battery, a nickel-metal hydride battery, or a lead-acid battery, or an electrochemical capacitor, such as an electric double layer capacitor.

[0119] The outline of the present disclosure is as follows: [1] An electrical storage device packaging material including a base material layer, a barrier layer including a metal foil layer, and a heat-sealable resin layer in this order, wherein a lubricant layer including a lubricant is provided on a surface of the heat-sealable resin layer, and the heat-sealable resin layer takes in the lubricant from the lubricant layer when the electrical storage device packaging material is placed in an environment of 40°C or higher, and the amount of the lubricant layer is 10 mg / m ２The casing material for a storage battery device, which can be configured as follows: [2] The casing material for a storage battery device according to [1], wherein the heat-sealable resin layer includes a sealant layer, and the content of a lubricant in the sealant layer is less than 200 ppm by mass. [3] The casing material for a storage battery device according to [1] or [2], wherein the heat-sealable resin layer includes a sealant layer, and the sealant layer includes a polyolefin resin. [4] The casing material for a storage battery device according to any of [1] to [3], wherein the lubricant included in the lubricant layer is a fatty acid amide. [5] The casing material for a storage battery device according to any of [1] to [4], wherein the lubricant layer is obtained by coating a composition containing the lubricant. [6] The casing material for a storage battery device according to any of [1] to [5], wherein the surface of the heat-sealable resin layer on the side of the lubricant layer has a surface roughness Sa of 1.0 μm or less. [7] The casing material for a storage battery device according to any of [1] to [6], further comprising an adhesive layer between the base layer and the barrier layer. [8] The packaging material for a storage battery device according to any one of [1] to [7], wherein the surface of the lubricant layer of the packaging material has a static friction coefficient of 0.75 or more at 60°C. [9] The packaging material for a storage battery device according to any one of [1] to [8], wherein the surface of the lubricant layer of the packaging material has a static friction coefficient of 0.4 or less at 23°C.

[10] The packaging material for a storage battery device according to any one of [1] to [9], wherein the storage battery device is an all-solid-state battery.

[11] A storage battery device comprising a battery cell and an outer container that houses the battery cell, the outer container being obtained using the packaging material for a storage battery device according to any one of [1] to

[10] .

[12] The storage battery device according to

[11] , wherein the storage battery device is an all-solid-state battery.

[0120] Hereinafter, the present disclosure will be described more specifically with reference to examples and comparative examples, but the present disclosure is not limited to the following examples.

[0121] [Materials Used] The materials used in the examples and comparative examples are shown below.

[0122] <Base Layer> As the base layer, easily moldable PET (manufactured by Unitika Ltd., thickness: 25 μm) was used.

[0123] <Resin composition for forming first adhesive layer> As the resin composition for forming the first adhesive layer, a polyester urethane adhesive was used which was prepared by blending a polyester polyol (manufactured by Toyo-Morton Co., Ltd., product name: TMK-55) as a base agent and a TDI or IPDI-based isocyanate (manufactured by Toyo-Morton Co., Ltd., product name: CAT-RT1) as a curing agent, and diluting the mixture with a solvent.

[0124] <Barrier Layer> The barrier layer used was a layer formed by forming a first corrosion prevention treatment layer and a second corrosion prevention treatment layer on both sides of a metal foil layer.

[0125] (Metal Foil Layer) Annealed and degreased soft aluminum foil (manufactured by Toyo Aluminum K.K., product name: 8079 material, thickness: 40 μm) was used as the metal foil layer. (Materials for Forming First Corrosion Prevention Treatment Layer (Substrate Layer Side) and Second Corrosion Prevention Treatment Layer (Sealant Layer Side)) The following (CL-1) and (CL-2) were used as materials for forming the first corrosion prevention treatment layer (substrate layer side) and the second corrosion prevention treatment layer (sealant layer side). (CL-1): "Sodium polyphosphate-stabilized cerium oxide sol" obtained by using distilled water as a solvent and adjusting the solids concentration to 10% by mass. The sodium polyphosphate-stabilized cerium oxide sol was obtained by blending 10 parts by mass of Na salt of 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)" obtained by adjusting the solid content concentration to 5% by mass using distilled water as a solvent.

[0126] <Resin Composition for Forming Adhesive Resin Layer> An adhesive resin (homopolypropylene (PP)-based acid-modified polypropylene resin composition, manufactured by Mitsui Chemicals, Inc.) was prepared as a resin for forming an adhesive resin layer.

[0127] <Resin composition for forming sealant layer> Using a twin-screw extruder, a resin composition for forming a sealant layer containing block polypropylene (manufactured by SunAllomer Co., Ltd., product name: PC684S) and a fatty acid amide as a lubricant was kneaded to prepare a resin composition for forming a sealant layer so that the lubricant content was the value shown in Table 1. Here, the unit of the lubricant content in the resin composition for forming a sealant layer is "ppm by mass".

[0128] <Lubricant Layer-Forming Composition> A dispersion containing a fatty acid amide (product name: "Fatty Acid Amide E", manufactured by Kao Corporation) and a solvent consisting of isopropyl alcohol was used as the lubricant layer-forming composition. The content of the fatty acid amide in the dispersion was set to a concentration of 1.0 mass % in accordance with the target coating amount.

[0129] [Preparation of Packaging Materials] (Examples 1 to 5 and Comparative Example 1) First, a first corrosion prevention treatment layer and a second corrosion prevention treatment layer were provided on a metal foil layer by the following procedure to form a barrier layer. That is, (CL-1) was first applied to both sides of the metal foil 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 The coating was performed by microgravure coating so that the coating was as follows: In this way, composite layers consisting of (CL-1) and (CL-2) were formed on both sides of the metal foil layer as first and second corrosion prevention treatment layers, respectively, to obtain barrier layers. These composite layers exhibit corrosion prevention performance by combining the two types of (CL-1) and (CL-2).

[0130] Next, the first corrosion prevention treatment layer side of the barrier layer was attached to the substrate layer by dry lamination using a resin composition for forming a first adhesive layer, thereby obtaining a laminate (first laminate) of the barrier layer and the substrate layer. Specifically, a polyurethane-based adhesive was applied to the surface of the barrier layer facing the first corrosion prevention treatment layer so that the thickness after curing would be 5 μm, and the adhesive was dried at 80° C. for 1 minute, then laminated to the substrate layer, and aged at 60° C. for 120 hours to obtain the first laminate.

[0131] Next, the first laminate was set on the unwinding section of an extrusion laminator, and the adhesive resin composition and the sealant layer-forming resin composition were co-extruded onto the second corrosion prevention treatment layer at 270°C and 100m / min to form a heat-sealable resin layer having a thickness of 80µm, consisting of an adhesive resin layer and a sealant layer laminated in this order, to obtain a second laminate. At this time, the content of the lubricant in the sealant layer was as shown in Table 1.

[0132] Next, the lubricant layer-forming composition was applied onto the sealant layer of the heat-sealable resin layer of the second laminate so that the amount of the lubricant layer after drying was 30 mg / m as shown in Table 1. ２ In this manner, an exterior packaging material (substrate layer / first adhesive layer / barrier layer / thermal fusion resin layer (adhesive resin layer / sealant layer) / lubricant layer) was produced, in which the surface roughness Sa of the surface of the lubricant layer was the value shown in Table 1.

[0133] Comparative Example 2 An exterior material (substrate layer / first adhesive layer / barrier layer / thermal fusion resin layer (adhesive resin layer / sealant layer)) was produced in the same manner as in Example 1, except that the content of the lubricant in the resin composition for forming a sealant layer was as shown in Table 1 and no lubricant layer was formed on the sealant layer, so that the surface roughness Sa of the surface of the sealant layer had the value shown in Table 1.

[0134] [Evaluation] <Moldability> For the packaging materials produced in the Examples and Comparative Examples, the molding limit for deep drawing was determined by the following method, and the moldability was evaluated based on the molding limit. First, a rectangular section measuring 120 mm in the TD direction and 200 mm in the MD direction was cut out as a test sheet from the packaging materials obtained in the Examples and Comparative Examples. This test sheet was placed in a molding device with the lubricant layer or sealant layer facing upward. The molding depth of the molding device was then set to 3.0 to 8.0 mm in 0.5 mm increments, and cold molding was performed in an environment of room temperature 23°C and a dew point temperature of -35°C. At this time, a punch mold having a rectangular cross section of 70 mm x 80 mm, a punch radius (RP) of 1.00 mm on the bottom, and a punch corner radius (RCP) of 1.00 mm on the side was used. In addition, a die mold having a die radius (RD) of 1.00 mm on the opening top surface was used. During molding, the test sheet was pressed with a pressing pressure (surface pressure) of 0.8 MPa, and molding was performed on a molding area (TD direction 80 mm x MD direction 70 mm) of half the area of ​​the test sheet (TD direction 120 mm x MD direction 100 mm). The position of the molding area in the test sheet is as shown by the dashed line in Figure 4. As shown in Figure 4, the molding area M is located at a position where the shortest distance from the short side P of the test sheet is 30 mm and the shortest distance from the long side Q of the test sheet is 20 mm. Then, the presence or absence of breaks and pinholes in the pockets formed by molding was visually confirmed while shining a light on the test sheet, and the maximum molding limit (molding depth) at which deep drawing molding could be performed without the occurrence of either breaks or pinholes was determined. Then, the moldability was evaluated based on the following evaluation criteria according to the molding limit. The results are shown in Table 1. (Evaluation criteria) ⊚: Forming limit is 5 mm or more ◯: Forming limit is 4.0 mm or more and less than 5.0 mm ×: Forming limit is less than 4.0 mm

[0135] <Slip-preventing Effect on Battery Cells> Two rectangular test sheets measuring 120 mm in the transverse direction and 200 mm in the machine direction were cut from the exterior packaging materials obtained in the Examples and Comparative Examples. Separately, Cu foil measuring 180 mm long, 100 mm short, and 2 mm thick was prepared for use in the negative electrode of the battery cell. The Cu foil used in the battery cell was then placed between the two test sheets, and the battery cell was pressed with a force of 20 kg via the test sheet using two stainless steel press plates to prepare a test specimen. This test specimen was then placed in a vibration tester (product name: "General-Purpose Vibration Tester," manufactured by IMV) and vibrated. After the vibration test, the test specimen was visually inspected to determine whether the Cu foil had moved from the test sheet. The slip-preventing effect of the test sheet on the Cu foil was evaluated based on the following evaluation criteria. The results are shown in Table 1. (Evaluation Criteria) ○: The Cu foil was not displaced relative to the test sheet before the test. ×: The position of the Cu foil is misaligned with respect to the test sheet before the test

[0136] <Amount of lubricant layer after storage at 40°C> A rectangular section of 120 mm in the TD direction x 200 mm in the MD direction was cut out as a test sheet from the packaging materials obtained in the Examples and Comparative Examples. Then, this test sheet was stored in an environment of 40°C for 2 weeks (336 hours), and then the amount of the lubricant layer was measured. The amount of the lubricant layer was measured as follows. First, the lubricant layer of the test sheet was washed with chloroform as a solvent for dissolving the lubricant, and the obtained liquid was analyzed by GC-MS (Gas Chromatography-Mass spectrometry) to measure the amount of lubricant in the liquid. The amount of lubricant was then calculated based on the following formula. The results are shown in Table 1. The amount of lubricant layer (mg / m ２ ) = 100 × measured amount of lubricant (mg) / surface area of ​​lubricant layer of test sheet (m ２ )

[0137]

[0138] From the results shown in Table 1, the coating amount of the lubricant layer was 0 mg / m ２ In Examples 1 to 5 and Comparative Example 1, where the coating amount of the lubricant layer was greater, the moldability was rated as ⊚ or ◯, whereas in Examples 1 to 5 and Comparative Example 1, where the coating amount of the lubricant layer was 0 mg / m２ In Comparative Example 2, the amount of the lubricant layer after storage at 40°C was 10 mg / m ２ In the following Examples 1 to 5, the lubricant layer had a lubricant suppression effect on the battery cell of 0 mg / m2 after storage at 40°C. ２ In Comparative Examples 1 and 2, which had more samples, the effect of suppressing slipperiness of the battery cell was rated ×. From the above, it was confirmed that the exterior packaging material for an electricity storage device according to the present disclosure has excellent formability and can suppress slipperiness of the battery cell even when the battery cell of the electricity storage device is placed in an environment of 40°C or higher while being pressurized.

[0139] DESCRIPTION OF SYMBOLS 10, 20... Packaging material for electricity storage device, 11... Base material layer, 12a... Outer adhesive layer, 12b... Inner adhesive layer, 13... Metal foil layer, 14a... First corrosion prevention treatment layer, 14b... Second corrosion prevention treatment layer, 15... Adhesive resin layer (heat-sealable resin layer), 16... Sealant layer (heat-sealable resin layer), 17... Barrier layer, 18... Lubricant layer, 50... Electricity storage device, 52... Battery cell, 53... Metal terminal, 54... Outer container.

Claims

1. An electrical storage device packaging material comprising a base layer, a barrier layer including a metal foil layer, and a heat-sealing resin layer in this order, the heat-sealing resin layer being provided with a lubricant layer including a lubricant on its surface, the heat-sealing resin layer taking in the lubricant from the lubricant layer when the electrical storage device packaging material is placed in an environment of 40°C or higher, and the amount of the lubricant layer being 10 mg / m ２ The exterior material for an electricity storage device can be as follows:

2. The packaging material for a storage battery device according to claim 1, wherein the heat-sealable resin layer includes a sealant layer, and the sealant layer has a lubricant content of less than 200 ppm by mass.

3. The packaging material for a storage battery device according to claim 1, wherein the heat-sealing resin layer includes a sealant layer, and the sealant layer includes a polyolefin resin.

4. The exterior material for a storage battery device according to claim 1, wherein the lubricant contained in the lubricant layer is a fatty acid amide.

5. The exterior material for a storage battery device according to claim 1, wherein the lubricant layer is obtained by coating a composition containing the lubricant.

6. The packaging material for a storage battery device according to claim 1, wherein the surface roughness Sa of the surface of the heat-sealing resin layer on the side of the lubricant layer is 1.0 μm or less.

7. The packaging material for an electricity storage device according to claim 1, further comprising an adhesive layer between the base material layer and the barrier layer.

8. The packaging material for a storage battery device according to claim 1, wherein the surface of the lubricant layer of the packaging material has a static friction coefficient of 0.75 or more at 60°C.

9. The packaging material for a storage battery device according to claim 1, wherein the lubricant layer of the packaging material has a static friction coefficient of 0.4 or less at 23°C.

10. The exterior packaging material for an electricity storage device according to claim 1, wherein the electricity storage device is an all-solid-state battery.

11. An electricity storage device comprising: a battery cell; and an outer container for housing the battery cell, the outer container being obtained using the exterior material for electricity storage devices according to any one of claims 1 to 10.

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

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