Power storage device packaging material, power storage device packaging case, and power storage device

Abstract

A power storage device packaging material according to the present invention is formed by layering, in order, a base material layer, a barrier layer, and a sealant layer. The polyamide resin fraction of the entire base material layer is at least 80 mass%, the thickness of the base material layer is 18–22 μm, the thickness of the barrier layer is 27–43 μm, the thickness of the sealant layer is 17–33 μm, the thickness of the entire power storage device packaging material is 72–96 μm, and the sealant layer includes incompatible particles.

Description

Exterior material for power storage device, exterior case for power storage device, and power storage device

[0001] The present disclosure relates to an exterior material for an electricity storage device, an exterior case for an electricity storage device, and an electricity storage device.

[0002] In recent years, as mobile electrical devices such as smartphones and tablet terminals have become thinner and lighter, laminates comprising a heat-resistant resin layer / an adhesive layer / a metal foil layer / an adhesive layer / a thermoplastic resin layer (an inner sealant layer) have been used in place of conventional metal cans as the exterior packaging materials for the lithium ion secondary batteries, lithium polymer secondary batteries, lithium ion capacitors, electric double layer capacitors, and other electricity storage devices mounted thereon. Furthermore, power sources for electric vehicles and the like, large power sources for electricity storage applications, capacitors, and the like are increasingly being packaged with laminates (exterior packaging materials) having the above configuration.

[0003] There is an increasing demand for improved energy density in power storage devices. One method for improving energy density is to reduce the thickness of the packaging material. For example, Patent Document 1 discloses a battery packaging material comprising a laminate in which at least a substrate layer, a metal layer, and a sealant layer are sequentially stacked, the total thickness of the laminate being in the range of 50 to 80 μm, and the ratio of the sum of the thicknesses of the substrate layer and the metal layer to the total thickness of the laminate being in the range of 0.380 to 0.630. Furthermore, Patent Document 2 discloses a battery packaging material comprising a laminate in which at least a substrate layer, a metal layer, and a heat-sealable resin layer are sequentially stacked, the thickness of the substrate layer being 60% or more of the thickness of the metal layer. Patent Document 3 discloses a battery packaging material comprising a laminate in which at least a substrate layer, a metal layer, an adhesive layer, and a sealant layer are sequentially laminated, the adhesive layer being formed of an acid-modified polyolefin, the adhesive layer having a thickness of 15 μm to 50 μm, the sealant layer having a thickness of 15 μm to 50 μm, and the total thickness of the adhesive layer and the sealant layer being at least three times the thickness of the substrate layer. Patent Document 4 discloses an exterior material for a power storage device having a structure in which at least a substrate layer, an adhesive layer, a metal foil layer, a sealant adhesive layer, and a sealant layer are laminated in this order, the substrate layer being made of a polyester film, the metal foil layer being an aluminum foil having a corrosion prevention treatment layer on at least one side, and the ratio of the thickness of the substrate layer to the thickness of the metal foil layer (substrate layer / metal foil layer) being 0.25 to 1.00.

[0004] Patent Document 1: International Publication No. 2016 / 047790 Patent Document 2: Japanese Patent Application Laid-Open No. 2018-006280 Patent Document 3: Japanese Patent Application Laid-Open No. 2019-117799 Patent Document 4: Japanese Patent Application Laid-Open No. 2017-091767

[0005] Reducing the thickness of an exterior material tends to reduce the strength of the exterior material. Therefore, it is necessary to achieve both improved strength and reduced thickness. However, the exterior materials disclosed in Patent Documents 1 to 4 do not always achieve both strength and reduced thickness. Furthermore, an electricity storage device is manufactured by housing an electricity storage device main body in an exterior case obtained by molding the exterior material, and then joining the sealant layer by heat sealing. The exterior case is formed by subjecting the exterior material to processes such as deep drawing and stretch molding, but the exterior material tends to curl during the molding process, causing problems in the subsequent electricity storage device manufacturing process.

[0006] The present disclosure has been made in consideration of the above-described conventional circumstances, and aims to provide an exterior material for an electricity storage device that achieves both improved strength and thinning and is capable of suppressing curling during molding processing, as well as an exterior case for an electricity storage device and an electricity storage device that use the same.

[0007] Specific means for achieving the above object are as follows. <1> An electrical storage device packaging material including a base layer, a barrier layer, and a sealant layer laminated in this order, wherein a proportion of polyamide resin in the entire base layer is 80 mass % or more, the base layer has a thickness of 18 μm to 22 μm, the barrier layer has a thickness of 27 μm to 43 μm, the sealant layer has a thickness of 17 μm to 33 μm, and the electrical storage device packaging material has a total thickness of 72 μm to 96 μm, and the sealant layer contains incompatible particles. <2> The electrical storage device packaging material according to <1>, wherein the barrier layer contains a metal foil. <3> The electrical storage device packaging material according to <2>, wherein at least one surface of the metal foil has a chemical conversion coating. <4> The electrical storage device packaging material according to any one of <1> to <3>, wherein the sealant layer contains a propylene resin as a main component. <5> The packaging material for an electricity storage device according to <4>, wherein the propylene resin has an MFR of 1 g / 10 min to 25 g / 10 min, measured under conditions of a temperature of 230°C and a load of 2.16 kg. <6> The packaging material for an electricity storage device according to any one of <1> to <5>, wherein the sealant layer includes an unstretched resin film. <7> The packaging material for an electricity storage device according to any one of <1> to <6>, wherein, when the thickness of the base layer is X and the thickness of the barrier layer is Y, an X / Y value is 0.45 to 0.75. <8> The packaging material for an electricity storage device according to any one of <1> to <7>, wherein, when the thickness of the barrier layer is Y and the thickness of the sealant layer is Z, an Y / Z value is 1.2 to 2.2. <9> The packaging material for an electricity storage device according to any one of <1> to <8>, wherein the outer surface of the sealant layer has an interfacial developed area ratio Sdr of 3% or more. <10> The packaging material for an electricity storage device according to any one of <1> to <9>, wherein the average particle size of the incompatible particles is 1 μm to 10 μm. <11> The packaging material for an electricity storage device according to any one of <1> to <10>, wherein the content of the incompatible particles in the sealant layer as a whole is 10,000 ppm by mass to 20,000 ppm by mass.<12> An exterior case for an electricity storage device, which is a molded article of the exterior material for an electricity storage device according to any one of <1> to <11>. <13> An electricity storage device comprising: an electricity storage device main body; and an exterior member that houses the electricity storage device main body and includes the exterior material for an electricity storage device according to any one of <1> to <11>.

[0008] According to the present disclosure, it is possible to provide an exterior material for an electricity storage device that achieves both improved strength and thinning and is capable of suppressing curling during molding processing, as well as an exterior case for an electricity storage device and an electricity storage device that use the same.

[0009] Fig. 1 is a schematic cross-sectional view showing Example 1 of an exterior material for an electricity storage device according to the present disclosure. Fig. 2 is a schematic cross-sectional view showing Example 2 of an exterior material for an electricity storage device according to the present disclosure. Fig. 3 is a schematic cross-sectional view showing Example 3 of an exterior material for an electricity storage device according to the present disclosure. Fig. 4 is a schematic perspective view showing the components constituting the electricity storage device of Fig. 4 in a separated state. Fig. 5 is a view showing an example of a flange portion 37 having a curl angle of less than 90 degrees. Fig. 6 is a view explaining a method for preparing a measurement sample for an insulation test after heat sealing, and the state of the insulation test after heat sealing. Fig. 7 is a view explaining a method for preparing a measurement sample for an insulation test after sealing with impurities, and the state of the insulation test after heat sealing.

[0010] Hereinafter, embodiments of the present disclosure will be described in detail. However, the present disclosure is not limited to the following embodiments. In the following embodiments, components (including element steps, etc.) are not essential unless otherwise specified. The same applies to numerical values ​​and their ranges, and do not limit the present disclosure.

[0011] In the present disclosure, numerical ranges indicated using "to" include the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In numerical ranges described in stages in the present disclosure, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another staged numerical range. Furthermore, in numerical ranges described in the present disclosure, the upper or lower limit value of that numerical range may be replaced with a value shown in the examples. In the present disclosure, each component may contain multiple corresponding substances. When multiple substances corresponding to each component are present in the composition, the content or amount of each component means the total content or amount of the multiple substances present in the composition, unless otherwise specified. In the present disclosure, particles corresponding to each component may include multiple types of particles. When multiple types of particles corresponding to each component are present in the composition, the particle size of each component means the value for a mixture of the multiple types of particles present in the composition, unless otherwise specified. In the present disclosure, the term "layer" or "film" includes cases where the layer or film is formed over the entire area when the area where the layer or film is present is observed, as well as cases where the layer or film is formed over only a part of the area. In the present disclosure, the term "laminate" refers to stacking layers, and two or more layers may be bonded together, or two or more layers may be detachable.

[0012] In the present disclosure, the thickness of the exterior material for an electricity storage device or each layer can be measured using a scanning electron microscope (SEM). The thickness in the present disclosure is the average value when measured at five locations.

[0013] <Exposing Material for Electricity Storage Device> The exterior material for an electricity storage device according to the present disclosure is an exterior material for an electricity storage device including a base layer, a barrier layer, and a sealant layer laminated in this order, wherein the proportion of polyamide resin in the entire base layer is 80 mass % or more, the thickness of the base layer is 18 μm to 22 μm, the thickness of the barrier layer is 27 μm to 43 μm, the thickness of the sealant layer is 17 μm to 33 μm, and the overall thickness of the exterior material for an electricity storage device is 72 μm to 96 μm. In the exterior material for an electricity storage device according to the present disclosure, the sealant layer may contain incompatible particles.

[0014] The present inventors have discovered that in a packaging material for an electricity storage device having a base layer, a barrier layer, and a sealant layer laminated in this order, by setting the proportion of polyamide resin in the entire base layer to 80 mass % or more and setting the thicknesses of the base layer, barrier layer, and sealant layer and the overall thickness of the packaging material for an electricity storage device within predetermined ranges, a packaging material for an electricity storage device that achieves both improved strength and thinning and is capable of suppressing curling during molding can be obtained, and have completed the present invention. The layer structure and other aspects of the packaging material for an electricity storage device of the present disclosure will be described below.

[0015] (Substrate Layer) The exterior material for an electricity storage device includes a substrate layer. From the viewpoint of strength and formability, the proportion of polyamide resin in the entire substrate layer is 80% by mass or more. The proportion of polyamide resin is preferably 85% by mass or more, more preferably 90% by mass or more, and even more preferably 100% by mass. The substrate layer may be a single layer or a multilayer consisting of two or more layers. When the substrate layer is a single layer, the proportion of polyamide resin in the single layer substrate layer is 80% by mass or more. When the substrate layer is a multilayer consisting of two or more layers, the proportion of polyamide resin in the total of the two or more substrate layers is 80% by mass or more. Note that when other layers such as adhesive layers are interposed between two or more substrate layers, the "total of two or more substrate layers" includes the other layers.

[0016] Examples of the substrate layer include polyamide films such as nylon film. Examples of nylon films include nylon 6 film, 6,6 nylon film, and MXD nylon film. When the substrate layer is a multilayer structure consisting of two or more layers, all layers may be polyamide films, or the substrate layer may be composed of a polyamide film and another resin film. Examples of other resin films include polyester films such as polyethylene terephthalate (PET) film, polybutylene terephthalate (PBT) film, and polyethylene naphthalate (PEN) film. These films may also be stretched films. Examples of stretched films include biaxially stretched polyamide films such as biaxially stretched nylon film, biaxially stretched polybutylene terephthalate (PBT) film, biaxially stretched polyethylene terephthalate (PET) film, and biaxially stretched polyethylene naphthalate (PEN) film.

[0017] The thickness of the substrate layer is 18 μm to 22 μm, preferably 19 μm to 21 μm. When the substrate layer is a multi-layer structure consisting of two or more layers, the thickness of the substrate layer is the total thickness of the two or more substrate layers. When other layers such as adhesive layers are interposed between the two or more substrate layers, the "thickness of the substrate layer" includes the thickness of the other layers.

[0018] When another layer such as an adhesive layer is interposed between two or more base layers, the other layer can be an adhesive layer, etc. The adhesive layer constituting the base layer is not particularly limited, and examples thereof include a layer composed of a thermosetting adhesive or the like described below.

[0019] (Outer adhesive layer) An adhesive layer (also referred to as an outer adhesive layer) may be provided between the base material layer and the barrier layer described later, and the base material layer and the barrier layer may be integrated via the outer adhesive layer.

[0020] The adhesive constituting the outer adhesive layer is not particularly limited, and examples thereof include thermosetting adhesives. The thermosetting adhesive is not particularly limited, and examples thereof include olefin-based adhesives, epoxy-based adhesives, acrylic-based adhesives, and urethane-based adhesives. The thickness of the outer adhesive layer may be 1 μm to 5 μm. In particular, from the viewpoint of reducing the thickness and weight of the exterior material, the thickness of the outer adhesive layer is preferably 1 μm to 3 μm.

[0021] The outer adhesive layer may be a single layer or two or more layers. When the outer adhesive layer is a multi-layer, it may be a combination of an adhesive layer containing a colorant and an adhesive layer not containing a colorant, for example.

[0022] (Barrier Layer) The electrical storage device packaging material includes a barrier layer. The barrier layer serves to impart gas barrier properties to the packaging material, inhibiting the penetration of oxygen, moisture, and the like. The barrier layer is not particularly limited, and examples thereof include metal foil, vapor deposition film, and resin layer. Examples of vapor deposition films include metal vapor deposition film, inorganic oxide vapor deposition film, and carbon-containing inorganic oxide vapor deposition film. The metal foil is not particularly limited, and examples thereof include aluminum foil, SUS foil (stainless steel foil), Cu foil, Ni foil, and Ti foil. Among these, aluminum foil and SUS foil (stainless steel foil) are preferred. Examples of resins used in the resin layer include fluorine-containing resins and ethylene-vinyl alcohol copolymers. Examples of fluorine-containing resins include polymers mainly composed of chlorotrifluoroethylene (CTFE), polymers mainly composed of tetrafluoroethylene (TFE), polymers having fluoroalkyl groups, and polymers mainly composed of fluoroalkyl units.

[0023] The barrier layer may be a single layer or a multilayer consisting of two or more layers. In the case of a multilayer, it may be a laminate of layers of the same kind or a laminate of layers of different kinds. An example of a laminate of layers of different kinds is a combination of a vapor-deposited film and a resin layer.

[0024] The thickness of the barrier layer is set to 27 μm to 43 μm. If the thickness of the barrier layer is 27 μm or more, the occurrence of pinholes during rolling tends to be suppressed. If the thickness of the barrier layer is 43 μm or less, formability tends to be improved. The thickness of the barrier layer may be in the range of 30 μm to 40 μm, or may be in the range of 32 μm to 38 μm. If the barrier layer is a multi-layered layer consisting of two or more layers, the total thickness of the two or more layers is set to the above range.

[0025] From the viewpoint of gas barrier properties, the barrier layer preferably contains a metal foil. The barrier layer may be made of a metal foil. When the barrier layer contains a metal foil, the metal foil may be subjected to a chemical conversion treatment on at least one of the surface facing the base layer and the surface facing the sealant layer. For example, at least one surface of the metal foil may have a chemical conversion coating such as a corrosion prevention layer. By providing a chemical conversion coating such as a corrosion prevention layer, corrosion of the metal foil surface due to contents (such as a battery electrolyte) can be suppressed. For example, a corrosion prevention layer may be formed by subjecting the metal foil to a chemical conversion treatment by the following process. For example, a chemical conversion treatment can be performed on the surface of a degreased metal foil by applying any of the following solutions 1) to 3) above, followed by drying: 1) an aqueous solution of a mixture containing phosphoric acid, chromic acid, and at least one compound selected from the group consisting of metal salts of fluorides and non-metal salts of fluorides; 2) an aqueous solution of a mixture containing phosphoric acid, at least one resin selected from the group consisting of acrylic resins, chitosan derivative resins, and phenolic resins, and at least one compound selected from the group consisting of chromic acid and chromium (III) salts; or 3) an aqueous solution of a mixture containing phosphoric acid, at least one resin selected from the group consisting of acrylic resins, chitosan derivative resins, and phenolic resins, at least one compound selected from the group consisting of chromic acid and chromium (III) salts, and at least one compound selected from the group consisting of metal salts of fluorides and non-metal salts of fluorides.

[0026] The chemical conversion coating formed by chemical conversion treatment has a chromium deposition amount (per side) of 0.1 mg / m ２ ~50 mg / m ２ is preferred, and 2 mg / m ２~20 mg / m ２ is more preferred.

[0027] (Inner adhesive layer) An adhesive layer (also referred to as an inner adhesive layer) may be provided between the barrier layer and the sealant layer described later, and the barrier layer and the sealant layer may be integrated via the inner adhesive layer.

[0028] The adhesive constituting the inner adhesive layer is not particularly limited and may be, for example, a thermosetting adhesive, etc. The thermosetting adhesive is not particularly limited and may be, for example, an olefin-based adhesive, an epoxy-based adhesive, an acrylic-based adhesive, or an acid-modified polyolefin-based adhesive such as maleic anhydride-modified polypropylene.

[0029] The thickness of the inner adhesive layer may be 1 μm to 5 μm. In particular, from the viewpoint of reducing the thickness and weight of the exterior material, the thickness of the inner adhesive layer is preferably 1 μm to 3 μm.

[0030] (Sealant Layer) The packaging material for an electricity storage device includes a sealant layer. The sealant layer is a layer that serves to impart heat sealability to the packaging material. The sealant layer needs to include at least one heat-sealable resin layer, and may include two or three heat-sealable resin layers. From the viewpoint of imparting sealability, the sealant layer may include an unstretched resin film.

[0031] The sealant layer (for example, a heat-fusible resin layer) contains a heat-fusible resin, and may contain a lubricant, incompatible particles, other components described below, and the like, as needed.

[0032] The heat-fusible resin is selected from those having a melting point equal to or lower than the heat-fusible temperature so as to melt at the heat-fusible temperature. The heat-fusible resin is not particularly limited as long as it has the above melting point, and is preferably at least one selected from the group consisting of ethylene resin, propylene resin, olefin resin, acid-modified products thereof, and ionomer.

[0033] The sealant layer (e.g., a heat-sealable resin layer) preferably contains a propylene resin as a main component, and may contain an unstretched resin film containing a propylene resin as a main component. In the present disclosure, "containing a propylene resin as a main component" means that the proportion of the corresponding component is the highest in each layer, and for example, means that the content of the corresponding component is 50% by mass or more of the entire layer.

[0034] The propylene resin may be a block copolymer of propylene and a copolymerization component other than propylene, or a random copolymer of propylene and a copolymerization component other than propylene, or a random copolymer of propylene and at least one monomer selected from the group consisting of ethylene and α-olefins having 4 or more carbon atoms, or a block copolymer of propylene and at least one monomer selected from the group consisting of ethylene and α-olefins having 4 or more carbon atoms. Examples of the copolymerization component other than propylene include ethylene, α-olefins having 4 or more carbon atoms, and butadiene. Examples of the α-olefins having 4 or more carbon atoms include 1-butene, 1-hexene, 1-pentene, and 4-methyl-1-pentene.

[0035] The MFR of the propylene resin measured at a temperature of 230°C and a load of 2.16 kg may be 1 g / 10 min or more, 1 g / 10 min to 25 g / 10 min, or 2 g / 10 min to 15 g / 10 min. In the present disclosure, MFR refers to the MFR (melt flow rate) measured at a temperature of 230°C and a load of 2.16 kg in accordance with JIS K7210:1999.

[0036] The sealant layer (e.g., a heat-sealable resin layer) may contain components other than resin (other components). Examples of other components include antioxidants, plasticizers, ultraviolet absorbers, antifungal agents, colorants (pigments, dyes, etc.), antistatic agents, rust inhibitors, moisture absorbers, and oxygen absorbers. The plasticizer is not particularly limited, and examples thereof include glycerin fatty acid ester monoglycerides, acetylated glycerin fatty acid ester monoglycerides, glycerin fatty acid ester organic acid monoglycerides, glycerin fatty acid ester medium-chain fatty acid triglycerides, polyglycerin fatty acid esters, sorbitan fatty acid esters, propylene glycol fatty acid esters, special fatty acid esters, and higher alcohol fatty acid esters.

[0037] The sealant layer (e.g., the heat-fusible resin layer) may further contain a lubricant. Examples of the lubricant include, but are not limited to, fatty acid amides. Examples of the fatty acid amide include, but are not limited to, saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, methylol amides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, fatty acid ester amides, and aromatic bisamides.

[0038] The lubricant may or may not be contained in any of the sealant layers.

[0039] The sealant layer (e.g., a heat-fusible resin layer) may further contain incompatible particles. The incompatible particles are preferably non-melting particles. In the present disclosure, "non-melting particles" refer to particles that do not melt at 200°C, a general heating temperature for heat fusion.

[0040] The incompatible particles may be inorganic particles, organic particles, metal particles, composite particles thereof, etc. From the viewpoint of suppressing deformation due to heat during thermal melting, the incompatible particles are preferably inorganic particles, metal particles, or composite particles thereof, and from the viewpoint of further ensuring the insulating function of the sealant layer and reducing the weight, inorganic particles, organic particles, or composite particles thereof are preferred. From these overall viewpoints, it is more preferable that the incompatible particles include inorganic particles. One type of incompatible particles may be used alone, or two or more types may be used in combination.

[0041] Examples of inorganic particles include inorganic oxide particles (silica particles, alumina particles, titanium oxide particles, etc.), inorganic carbonate particles (calcium carbonate particles, barium carbonate particles, etc.), inorganic silicate particles (aluminum silicate particles, talc particles, kaolin particles, etc.), etc. Among these, silica particles are preferred from the viewpoint of the balance between anti-blocking effect and bubble suppression.

[0042] Examples of organic particles include acrylic resin particles, polyolefin resin particles (polyethylene resin particles, polypropylene resin particles, etc.), and polystyrene resin particles.

[0043] The metal particles include aluminum particles.

[0044] In one embodiment, the average particle size of the incompatible particles may be 0.1 μm to 4.5 μm, or 0.5 μm to 4.0 μm. When the average particle size of the incompatible particles is 0.1 μm or more, the incompatible particles tend to function as an antiblocking agent, while when the average particle size of the incompatible particles is 4.5 μm or less, the generation of bubbles due to volatilization of the electrolyte solution, etc., tends to be suppressed. In another embodiment, the average particle size of the incompatible particles may be 1 μm to 10 μm, 2 μm to 8 μm, or 3 μm to 6 μm. The average particle size of the incompatible particles can also be measured by observing and measuring the cross section of the sealant layer with a scanning electron microscope. Specifically, the sealant layer is embedded in a transparent epoxy resin, polished with a polisher, slurry, or the like, and the cross section of the sealant layer is observed and the particle size is measured. The average particle size is the arithmetic mean value of the particle sizes of 50 incompatible particles.

[0045] The outermost layer of the sealant layer opposite the barrier layer preferably contains incompatible particles. The content of the incompatible particles in the outermost layer may be 1,000 ppm by mass to 4,000 ppm by mass, 1,000 ppm by mass to 3,500 ppm by mass, or 1,000 ppm by mass to 3,000 ppm by mass. The content of the incompatible particles in the sealant layer as a whole is preferably 10,000 ppm by mass to 20,000 ppm by mass, or may be 11,000 ppm by mass to 19,000 ppm by mass, 12,000 ppm by mass to 18,000 ppm by mass, or 13,000 ppm by mass to 17,000 ppm by mass.

[0046] When the energy storage device main body is housed and sealed in an exterior member made of a packaging material, the electrodes and other energy storage device elements and electrolyte are first placed inside the exterior member and temporarily sealed, allowing the electrodes to soak in the electrolyte. During this process, the electrolyte partially decomposes, generating gas. The generated gas is then released to the outside, and the sealing is performed again. This sealing is performed with the electrolyte (impurities) adhering between the sealant layers (see FIG. 9 ). Hereinafter, this sealing is referred to as an "impurity seal." Due to the above-described method of sealing the energy storage device main body with the exterior member, it has been found that even if the exterior material itself has high electrical resistance and excellent insulation, its electrical resistance may decrease after the impurity seal. Therefore, it is preferable that the interface development area ratio Sdr of the outer surface of the sealant layer be 3% or more. In the present disclosure, the "outer surface of the sealant layer" refers to the surface of the sealant layer opposite the barrier layer. When the sealant layer is composed of two or more heat-sealable resin layers, it is preferable that the interfacial developed area ratio Sdr of the heat-sealable resin layer that is located on the outermost layer opposite to the barrier layer, among the heat-sealable resin layers that constitute the sealant layer, is 3% or more.

[0047] The sealant layer contains incompatible particles, resulting in excellent insulation properties even after sealing against impurities. The reason for this is unclear, but is presumed to be as follows: When sealing against impurities, the electrolyte is trapped between the sealant layers. Therefore, it is presumed that gas is generated from the electrolyte present between the sealant layers after sealing against impurities, destroying part of the outer packaging material, resulting in a decrease in insulation properties. In contrast, the packaging material of the present disclosure has an interface development area ratio Sdr of 3% or more on the outer surface of the sealant layer, and has appropriate roughness. This makes it easy for the electrolyte present between the sealant layers to escape and be removed. Therefore, it is presumed that damage to the outer packaging material caused by the presence of electrolyte between the sealant layers after sealing against impurities is suppressed, resulting in excellent insulation properties even after sealing against impurities. The effective numerical range of the interface development area ratio Sdr (i.e., 3% or more) was discovered experimentally.

[0048] In the present disclosure, the interfacial developed area ratio Sdr is defined in ISO 25178 and is an index that indicates how much the developed area (surface area) of a target area increases relative to the area of ​​the target area. The Sdr of a completely flat surface is 0. The interfacial developed area ratio Sdr is measured using a scanning white light interferometer (e.g., Hitachi High-Tech Corporation, Model: VS1330).

[0049] The Sdr of the outer surface of the sealant layer may be 3% or more, 3.5% or more, or 4% or more. The Sdr of the outer surface of the sealant layer is not particularly limited, and may be 10% or less from the viewpoint of heat-sealing properties.

[0050] The thickness of the sealant layer is 17 μm to 33 μm, and may be 20 μm to 30 μm, or 22 μm to 28 μm. When the layers other than the sealant layer of the packaging material for an electricity storage device have the same configuration, if the thickness of the sealant layer is 17 μm or more, curling after molding tends to be suppressed. If the thickness of the sealant layer is 33 μm or less, the limit molding depth tends to be deep. When the sealant layer is a multilayer consisting of two or more layers, the thickness of the sealant layer is the total thickness of the two or more sealant layers.

[0051] When the sealant layer is a single layer of a heat-sealable resin, the heat-sealable resin layer may contain, as a main component, a random copolymer of propylene and a copolymer component other than propylene.

[0052] When the sealant layer is a single heat-sealable resin layer, the thickness of the heat-sealable resin layer is set to 17 μm to 33 μm, may be 20 μm to 30 μm, or may be 22 μm to 28 μm.

[0053] When the sealant layer is a two-layer heat-sealable resin layer, the heat-sealable resin layer on the barrier layer side may be a block copolymer of propylene and a copolymer component other than propylene, and the heat-sealable resin layer on the opposite side to the barrier layer may contain, as a main component, a random copolymer of propylene and a copolymer component other than propylene.

[0054] When the sealant layer is a two-layer heat-sealable resin layer, the thickness of the heat-sealable resin layer on the barrier layer side may be 10 μm to 25 μm, or 12 μm to 20 μm. The thickness of the heat-sealable resin layer on the opposite side to the barrier layer may be 2 μm to 15 μm, or 3 μm to 10 μm. However, the total thickness of the two heat-sealable resin layers is set to a range of 17 μm to 33 μm.

[0055] When the sealant layer comprises a first heat-sealable resin layer, a second heat-sealable resin layer, and a third heat-sealable resin layer in this order from the barrier layer side, the first heat-sealable resin layer may comprise, as a main component, a random copolymer of propylene and other copolymer components excluding propylene, the second heat-sealable resin layer may comprise, as a main component, a block copolymer of propylene and other copolymer components excluding propylene, and the third heat-sealable resin layer may comprise, as a main component, a random copolymer of propylene and other copolymer components excluding propylene.

[0056] The thickness of the first heat-sealable resin layer may be 2 μm to 15 μm or 8 μm to 12 μm. The thickness of the second heat-sealable resin layer may be 10 μm to 25 μm or 12 μm to 20 μm. The thickness of the third heat-sealable resin layer may be 2 μm to 15 μm or 3 μm to 10 μm. However, the total thickness of the three heat-sealable resin layers is set to a range of 17 μm to 33 μm.

[0057] When the thickness of the base layer constituting the electrical storage device packaging material is X and the thickness of the barrier layer is Y, the X / Y value is preferably 0.45 or more. The X / Y value is preferably 0.75 or less. The X / Y value is preferably 0.45 to 0.75, and more preferably 0.5 to 0.7. When the thickness of the barrier layer constituting the electrical storage device packaging material is Y and the thickness of the sealant layer is Z, the Y / Z value is preferably 1.2 or more. The Y / Z value is preferably 2.2 or less. The Y / Z value is preferably 1.2 to 2.2, and more preferably 1.3 to 2.0.

[0058] The thickness of the entire packaging material for an electricity storage device is set to 72 μm to 96 μm, preferably 75 μm to 92 μm, more preferably 75 μm to 90 μm, and even more preferably 81 μm to 85 μm.

[0059] Hereinafter, examples of packaging materials for electricity storage devices according to the present disclosure will be shown with reference to Figures 1 to 3. Figures 1 to 3 are schematic cross-sectional views showing Examples 1 to 3 of packaging materials for electricity storage devices according to the present disclosure.

[0060] The packaging material 1 for an electricity storage device shown in Fig. 1 includes, in this order, a base material layer 2, a barrier layer 4, and a sealant layer 3. The sealant layer 3 includes, in this order from the barrier layer 4 side, a first heat-sealable resin layer 7, a second heat-sealable resin layer 8, and a third heat-sealable resin layer 9. An outer adhesive layer 5 is provided between the base material layer 2 and the barrier layer 4, and an inner adhesive layer 6 is provided between the barrier layer 4 and the first heat-sealable resin layer 7.

[0061] The exterior packaging material 10 for an electricity storage device shown in Fig. 2 includes, in this order, a base material layer 2, a barrier layer 4, and a sealant layer 13. The sealant layer 13 includes, in this order from the barrier layer 4 side, a first heat-sealable resin layer 17 and a second heat-sealable resin layer 18. An outer adhesive layer 5 is provided between the base material layer 2 and the barrier layer 4, and an inner adhesive layer 6 is provided between the barrier layer 4 and the first heat-sealable resin layer 17.

[0062] The packaging material 20 for an electricity storage device shown in Fig. 3 includes, in this order, a base material layer 2, a barrier layer 4, and a sealant layer 27. The sealant layer 27 is a heat-sealable resin layer. An outer adhesive layer 5 is provided between the base material layer 2 and the barrier layer 4, and an inner adhesive layer 6 is provided between the barrier layer 4 and the sealant layer 27.

[0063] <Method for manufacturing an electrical storage device exterior material> The method for manufacturing an electrical storage device exterior material is not particularly limited as long as the above-described electrical storage device exterior material can be obtained. As an example of the method for manufacturing an electrical storage device exterior material, a method for manufacturing an electrical storage device exterior material 1 shown in FIG. 1 will be described below.

[0064] A laminate A is prepared in which a base layer 2, an outer adhesive layer 5, and a barrier layer 4 are laminated in this order. The laminate A can be produced by a dry lamination method in which an adhesive component for forming the outer adhesive layer 5 is applied to the base layer 2 or the barrier layer 4 by gravure coating, roll coating, or the like, dried, and then the barrier layer 4 or the base layer 2 is laminated thereon. If the adhesive component is a curable resin, the outer adhesive layer 5 is cured by heating or the like after the barrier layer 4 or the base layer 2 is laminated on the outer adhesive layer 5.

[0065] Next, a sealant layer 3 is provided on the barrier layer 4 of the laminate A. The sealant layer 3 may be formed in advance on a resin film and placed on the barrier layer 4 (first method), or the sealant layer 3 may be formed by applying a resin material for forming the sealant layer 3 onto the barrier layer 4 by extrusion molding, coating, or the like (second method). In the first method, a resin film that is a multilayer laminate including a first heat-sealable resin layer 7, a second heat-sealable resin layer 8, a third heat-sealable resin layer 9, and the like can be produced by a co-extrusion method or the like.

[0066] In the first method, the barrier layer 4 and the sealant layer 3 are bonded together by the inner adhesive layer 6. In the second method, the inner adhesive layer 6 may be omitted or may be provided.

[0067] When the inner adhesive layer 6 is provided between the barrier layer 4 and the sealant layer 3, the inner adhesive layer 6 and the sealant layer 3 can be laminated by extrusion lamination, thermal lamination, sandwich lamination, dry lamination, or the like. Examples of extrusion lamination include a method (co-extrusion lamination, tandem lamination) in which the inner adhesive layer 6 and the sealant layer (first heat-fusible resin layer 7, second heat-fusible resin layer 8, and third heat-fusible resin layer 9) are extruded onto the barrier layer 4 of the laminate A. Examples of thermal lamination include a method in which a laminate B of the inner adhesive layer 6 and the sealant layer 3 is separately formed, and the inner adhesive layer 6 of the laminate B is laminated so as to face the barrier layer 4 of the laminate A, and a method in which a laminate C having the inner adhesive layer 6 is formed on the barrier layer 4 of the laminate A, and the inner adhesive layer 6 of the laminate C is laminated to the sealant layer 3. Examples of the sandwich lamination method include a method in which a molten inner adhesive layer 6 is poured between the barrier layer 4 of the laminate A and a sealant layer 3 that has been preformed in the form of a film. An adhesive resin such as an acid-modified polyolefin adhesive may be poured between the barrier layer 4 of the laminate A and the sealant layer 3 that has been preformed in the form of a film, and the resulting sandwich laminate may be heated with a thermal adhesive roll to bond the barrier layer 4 and the sealant layer 3 via the inner adhesive layer 6 (thermal adhesive resin). Examples of the dry lamination method include a method in which an adhesive component for forming the inner adhesive layer 6 is solution-coated on the barrier layer 4 of the laminate A, followed by drying or baking, and then the sealant layer 3 that has been preformed in the form of a film is laminated on this inner adhesive layer 6.

[0068] <Outer casing for electricity storage device> The outer casing for an electricity storage device of the present disclosure is a molded product of the aforementioned outer casing material for an electricity storage device. The outer casing material for an electricity storage device may be molded by deep drawing, stretch molding, or the like. Examples of the shape of the outer casing for an electricity storage device include outer casing 30 shown in Figures 4 and 5 described below.

[0069] The electricity storage device according to the present disclosure includes an electricity storage device main body and an exterior member that houses the electricity storage device main body and includes the exterior material for an electricity storage device according to the present disclosure. The exterior member may include an exterior case for an electricity storage device according to the present disclosure.

[0070] An example of an electricity storage device 100 configured using the exterior packaging material for an electricity storage device (exterior packaging material) 1 of the present disclosure is shown in Figures 4 and 5. Figure 4 is a schematic cross-sectional view showing an example of an electricity storage device. Figure 5 is a schematic perspective view showing a state in which components constituting the electricity storage device of Figure 4 are separated. The electricity storage device 100 is a lithium-ion secondary battery.

[0071] 4 and 5 , the exterior member 15 is configured by an exterior case for an electricity storage device (exterior case) 30, which is a molded body of the exterior material 1, and the planar exterior material 1. The electricity storage device main body 110 is housed in the housing recess of the exterior case 30. The planar exterior material 1 is then placed with the sealant layer 3 side facing inward (the lower side in FIGS. 4 and 5 ), and the sealant layer 3 on the periphery of the planar exterior material 1 and the sealant layer 3 on the flange portion (sealing periphery) 37 of the exterior case 30 are sealed and joined by heat fusion (heat sealing).

[0072] 4, reference numeral 39 denotes a heat-sealed portion where the peripheral edge of the exterior material 1 and a flange portion (sealing peripheral edge) 37 of the exterior case 30 are joined (welded) together. In the electricity storage device 100, the tip end of the tab lead connected to the electricity storage device main body 110 is led out of the exterior member 15, but is not shown in the drawing.

[0073] The power storage device main body 110 is not particularly limited, and examples thereof include a battery main body, a capacitor main body, and a condenser main body.

[0074] From the viewpoint of ensuring reliable sealing, the width of the heat-sealed portion 39 is preferably set to 0.5 mm or more, and more preferably set to 3 mm to 15 mm.

[0075] The shape of the exterior member 15 is not limited to the shapes shown in Figures 4 and 5, and the edges may be heat-sealed by a pair of planar exterior materials 1, or may be heat-sealed by a pair of exterior cases 30.

[0076] Next, examples of the present disclosure will be described, but the present disclosure is not particularly limited to these examples.

[0077] [Example 1] A chemical conversion coating was formed by applying a chemical conversion treatment solution consisting of phosphoric acid, polyacrylic acid (acrylic resin), a chromium (III) salt compound, water, and alcohol to both sides of a 40 μm thick aluminum foil and then drying at 180° C. The chromium deposition amount of this chemical conversion coating was 10 mg / m per side. ２ It was.

[0078] Next, a 20 μm-thick biaxially oriented nylon 6 film was dry-laminated (attached) to one side of the chemically treated aluminum foil via a two-component curing urethane adhesive, thereby producing a laminate A having a base layer, an outer adhesive layer, and a barrier layer laminated in this order.

[0079] Next, a sealant film having a thickness of 20 μm, which was composed of propylene resin (ethylene-propylene random copolymer) and specific particles, and the content of the specific particles was as shown in Particle composition 4 in Table 1, was prepared.

[0080] An adhesive resin, which was acid-modified polypropylene (ethylene-propylene random copolymer), was prepared. The adhesive resin was poured between the other side of the aluminum foil and the sealant film, sandwich-laminated, heated with a thermal adhesive roll, and then wound around a roll shaft. After aging (heating) at 40°C for 10 days, the resulting material was pulled out from the roll shaft to obtain an exterior material for an electricity storage device. The thickness of each layer is as shown in Table 3.

[0081] [Example 2] A sealant film having a thickness of 25 μm was prepared, which was composed of propylene resin (ethylene-propylene random copolymer) and specific particles, with the content of the specific particles being as shown in particle composition 4 in Table 1. Except for using the obtained sealant film, an exterior material for an electricity storage device was obtained in the same manner as in Example 1. The thickness of each layer is as shown in Table 3.

[0082] [Example 3] A chemical conversion coating was formed by applying a chemical conversion treatment solution consisting of phosphoric acid, polyacrylic acid (acrylic resin), a chromium (III) salt compound, water, and alcohol to both sides of an aluminum foil having a thickness of 35 μm, followed by drying at 180° C. The chromium deposition amount of this chemical conversion coating was 10 mg / m per side. ２ Separately, a sealant film having a thickness of 25 μm was prepared, which was composed of propylene resin (ethylene-propylene random copolymer) and specific particles, and the content of the specific particles was as shown in Particle composition 3 in Table 1. An exterior material for an electricity storage device was obtained in the same manner as in Example 1, except that the obtained aluminum foil and sealant film were used. The thickness of each layer is as shown in Table 3.

[0083] [Example 4] A chemical conversion coating was formed by applying a chemical conversion treatment solution consisting of phosphoric acid, polyacrylic acid (acrylic resin), a chromium (III) salt compound, water, and alcohol to both sides of a 30 μm thick aluminum foil and then drying at 180° C. The chromium deposition amount of this chemical conversion coating was 10 mg / m per side. ２ Separately, a sealant film having a thickness of 20 μm was prepared, which was composed of propylene resin (ethylene-propylene random copolymer) and specific particles, and the content of the specific particles was as shown in Particle composition 3 in Table 1. An exterior material for an electricity storage device was obtained in the same manner as in Example 1, except that the obtained aluminum foil and sealant film were used. The thickness of each layer is as shown in Table 3.

[0084] Example 5 A sealant film having a thickness of 30 μm was obtained, which was composed of a propylene resin (ethylene-propylene random copolymer) and specific particles, with the content of the specific particles being as shown in Particle composition 3 in Table 1. A packaging material for an electricity storage device was obtained in the same manner as in Example 1, except that the obtained sealant film was used. The thickness of each layer was as shown in Table 3.

[0085] Example 6 A biaxially stretched nylon 6 film with a thickness of 22 μm was prepared. Separately, a sealant film with a thickness of 25 μm was prepared, which was composed of propylene resin (ethylene-propylene random copolymer) and specific particles, with the content of the specific particles being as shown in Particle Composition 3 in Table 1. An exterior material for an electricity storage device was obtained in the same manner as in Example 1, except that the obtained biaxially stretched nylon 6 film and sealant film were used. The thickness of each layer is as shown in Table 3.

[0086] Comparative Example 1 A biaxially stretched nylon 6 film with a thickness of 25 μm was prepared. Separately, a sealant film with a thickness of 25 μm was obtained, which was composed of propylene resin (ethylene-propylene random copolymer) and specific particles, with the content of the specific particles being as shown in Particle Composition 1 in Table 1. An exterior material for an electricity storage device was obtained in the same manner as in Example 1, except that the obtained biaxially stretched nylon 6 film and sealant film were used. The thickness of each layer is as shown in Table 3.

[0087] Comparative Example 2 A chemical conversion coating was formed by applying a chemical conversion treatment solution consisting of phosphoric acid, polyacrylic acid (acrylic resin), a chromium (III) salt compound, water, and alcohol to both sides of a 35 μm thick aluminum foil and then drying at 180° C. The chromium deposition amount of this chemical conversion coating was 10 mg / m per side. ２ In addition, a biaxially stretched nylon 6 film having a thickness of 15 μm was prepared. Furthermore, a sealant film having a thickness of 30 μm was prepared, which was composed of propylene resin (ethylene-propylene random copolymer) and specific particles, and the content of the specific particles was as shown in Particle Composition 1 in Table 1. Except for using these aluminum foils, biaxially stretched nylon 6 film, and sealant film, an exterior material for an electricity storage device was obtained in the same manner as in Example 1. The thickness of each layer is as shown in Table 3.

[0088] Comparative Example 3 A chemical conversion coating was formed by applying a chemical conversion treatment solution consisting of phosphoric acid, polyacrylic acid (acrylic resin), a chromium (III) salt compound, water, and alcohol to both sides of a 50 μm thick aluminum foil and then drying at 180° C. The chromium deposition amount of this chemical conversion coating was 10 mg / m per side. ２ Separately, a sealant film having a thickness of 25 μm was obtained, which was composed of propylene resin (ethylene-propylene random copolymer) and specific particles, and the content of the specific particles was as shown in Particle composition 1 in Table 1. Except for using the obtained aluminum foil and sealant film, an exterior material for an electricity storage device was obtained in the same manner as in Example 1. The thickness of each layer is as shown in Table 3.

[0089] Comparative Example 4 A chemical conversion coating was formed by applying a chemical conversion treatment solution consisting of phosphoric acid, polyacrylic acid (acrylic resin), a chromium (III) salt compound, water, and alcohol to both sides of an aluminum foil having a thickness of 25 μm, followed by drying at 180° C. The chromium deposition amount of this chemical conversion coating was 10 mg / m per side. ２ Separately, a sealant film having a thickness of 25 μm was obtained, which was composed of propylene resin (ethylene-propylene random copolymer) and specific particles, and the content of the specific particles was as shown in Particle composition 2 in Table 1. An exterior material for an electricity storage device was obtained in the same manner as in Example 1, except that the obtained aluminum foil and sealant film were used. The thickness of each layer is as shown in Table 3.

[0090] Comparative Example 5 A sealant film having a thickness of 40 μm was obtained, which was composed of a propylene resin (ethylene-propylene random copolymer) and specific particles, and the content of the specific particles was as shown in Particle composition 2 in Table 1. A packaging material for an electricity storage device was obtained in the same manner as in Example 1, except that the obtained sealant film was used. The thickness of each layer is as shown in Table 3.

[0091] Comparative Example 6 A chemical conversion coating was formed by applying a chemical conversion treatment solution consisting of phosphoric acid, polyacrylic acid (acrylic resin), a chromium (III) salt compound, water, and alcohol to both sides of a 30 μm thick aluminum foil and then drying at 180° C. The chromium deposition amount of this chemical conversion coating was 10 mg / m per side.２ Separately, a sealant film having a thickness of 15 μm was obtained, which was composed of propylene resin (ethylene-propylene random copolymer) and specific particles, and the content of the specific particles was as shown in Particle composition 2 in Table 1. Except for using the obtained aluminum foil and sealant film, an exterior material for an electricity storage device was obtained in the same manner as in Example 1. The thickness of each layer is as shown in Table 3.

[0092] Comparative Example 7 A chemical conversion coating was formed by applying a chemical conversion treatment solution consisting of phosphoric acid, polyacrylic acid (acrylic resin), a chromium (III) salt compound, water, and alcohol to both sides of an aluminum foil having a thickness of 25 μm, followed by drying at 180° C. The chromium deposition amount of this chemical conversion coating was 10 mg / m per side. ２ In addition, a biaxially stretched nylon 6 film having a thickness of 15 μm was prepared. Furthermore, a sealant film having a thickness of 30 μm was prepared, which was composed of propylene resin (ethylene-propylene random copolymer) and specific particles, and the content of the specific particles was as shown in particle composition 3 in Table 1. Except for using these aluminum foils, biaxially stretched nylon 6 film, and sealant film, an exterior material for an electricity storage device was obtained in the same manner as in Example 1. The thickness of each layer is as shown in Table 3.

[0093] Comparative Example 8 A biaxially stretched nylon 6 film with a thickness of 25 μm was prepared. Separately, a sealant film with a thickness of 40 μm was prepared, which was composed of propylene resin (ethylene-propylene random copolymer) and specific particles, with the content of the specific particles being as shown in Particle Composition 1 in Table 1. An exterior material for an electricity storage device was obtained in the same manner as in Example 1, except that the obtained biaxially stretched nylon 6 film and sealant film were used. The thickness of each layer is as shown in Table 3.

[0094] Comparative Example 9 A biaxially stretched nylon 6 film with a thickness of 22 μm was prepared. Separately, a sealant film with a thickness of 30 μm was prepared, which was composed of propylene resin (ethylene-propylene random copolymer) and specific particles, with the content of the specific particles being as shown in Particle Composition 3 in Table 1. An exterior material for an electricity storage device was obtained in the same manner as in Example 1, except that the obtained biaxially stretched nylon 6 film and sealant film were used. The thickness of each layer is as shown in Table 3.

[0095] - Thickness measurement and thinning evaluation - The thickness of each layer and exterior material was measured at a magnification of 400x using a scanning electron microscope (S-3400N (product name) manufactured by Hitachi High-Tech Corporation). The thickness of each layer and exterior material was measured at any five locations, and the arithmetic mean of the thicknesses obtained was taken as the thickness of each layer and exterior material. The thickness (total thickness) of each exterior material was evaluated according to the following criteria. The thinner the exterior material, the better the exterior material's thinning ability. The evaluation results are shown in Table 3. A: The thickness of the exterior material is 96 μm or less B: The thickness of the exterior material is more than 96 μm

[0096] -Molding Evaluation- The produced electrical storage device exterior material was cut into 100 mm x 125 mm pieces to prepare molding materials. Then, using a punch (punch shape: 33 mm x 54 mm, corner R: 2 mm, punch shoulder R: 1.3 mm) and a die (die shape: die shoulder R: 1 mm), deep drawing was performed using a press machine (product number: TP-25C-XZ) manufactured by Amada Co., Ltd. The deep drawing was performed in such a manner that the top surface of the punch was brought into contact with the sealant layer of the molding material, causing the base layer to protrude outward, and the forming depth D was changed in 0.5 mm increments. Then, a light was shone on the corners of the molded product, and the presence or absence of transmitted light due to pinholes, cracks, etc. was visually observed. The limit forming depth (mm) at which good molding without the occurrence of pinholes or cracks could be performed was determined, and the results were evaluated according to the following criteria. The evaluation results are shown in Table 3. A: Limit forming depth is 7.0 mm or more. B: Limit forming depth is less than 7.0 mm.

[0097] - Evaluation of puncture strength - The puncture strength of the packaging material for an electricity storage device was measured in accordance with JIS Z1707:2019. The puncture strength test was carried out according to the following steps 1 and 2. The puncture strength was evaluated according to the following criteria. The evaluation results are shown in Table 3. A: puncture strength of 17 N or more B: puncture strength of less than 17 N

[0098] Procedure 1: A test piece taken from the packaging material for an electricity storage device was fixed in a jig, and a semicircular needle with a diameter of 1.0 mm and a tip radius of 0.5 mm was pierced from the base material layer side at a test speed of 50±5 mm / min, and the maximum force (N) until the needle penetrated was measured. Procedure 2: Five or more test pieces were taken from the packaging material for an electricity storage device, and the test pieces were taken so as to be averaged over the entire width of the packaging material for an electricity storage device.

[0099] - Curl Evaluation - The produced exterior material for an electricity storage device was cut into a size of 180 mm in length x 100 mm in width to prepare a molding material. The center of the cut molding material was deep-drawn using a deep-drawing tool manufactured by Amada Co., Ltd. into a roughly rectangular parallelepiped shape of 55 mm in length x 35 mm in width x 5 mm in depth (a roughly rectangular parallelepiped shape with the base layer 2 on the outside and one side open; see FIG. 5 ), to obtain an exterior case 30 equipped with a flange portion 37. This exterior case 30 was left to stand for 24 hours in an environment of 23°C and 50% RH, and then the following measurements were performed on the exterior case 30.

[0100] The outer case 30 was placed on a horizontal surface as an installation surface with its central convex portion facing up (the outer case 30 was placed on the horizontal surface in a state in which it was turned upside down from the state shown in FIG. 5), i.e., the flange portion 37 was placed on the horizontal surface so that it faced downward. Next, the angle between this flange portion 37 and the horizontal surface was calculated. Specifically, an approximate right triangle was fitted to the curled flange portion 37, and the side of the right triangle parallel to the horizontal plane was designated x, and the side perpendicular to the horizontal plane was designated y. The inverse trigonometric function arctan (tan －１) was used to calculate the angle between the curled flange portion 37 and the horizontal plane. Of the flange portions 37 on the four sides of the molded body, the angle of the flange portion that was curled most toward the bottom side of the molded body was determined and evaluated according to the following criteria. The evaluation results are shown in Table 3. An example of a flange portion 37 with a curl angle of less than 90 degrees is shown in Figure 6, and an example of a flange portion 37 with a curl angle of more than 90 degrees is shown in Figure 7. A: Curl angle less than 90 degrees B: Curl angle 90 degrees or more

[0101] - Sdr Measurement - The Sdr of the outer surface of the sealant layer of the resulting exterior material (laminate) was measured using a scanning white light interference microscope (manufactured by Hitachi High-Technologies Corporation, model: VS1330).

[0102] -Insulation Test After Heat Sealing- A measurement sample for the insulation test was prepared as shown in Figure 8. First, a packaging material cut to 80 mm x 100 mm was prepared, and as shown in Figure 8(A), it was folded in half to 80 mm x 50 mm. Next, as shown in Figure 8(B), a tab lead 80 equipped with a tab sealant was sandwiched between the folded material, and the edge sandwiching the tab lead 80 (the bottom edge in Figure 8(B)) and the 80 mm edge (the side edge in Figure 8(B)) were each heat-sealed to form a bag. Next, as shown in Figure 8(C), a 1:1 (mass ratio) mixture of ethylene carbonate:diethyl carbonate, LiPF ６ 1 ml of 1 M electrolyte was poured in, and the remaining open 50 mm edge (the upper edge in FIG. 8(C)) was sealed. The battery was then left flat at 25°C for 24 hours. Next, as shown in FIG. 8(D), a portion of the outer layer of the packaging material was scraped off to form an exposed portion of the aluminum foil (barrier layer). Then, as shown in FIG. 8(E), the exposed portion of the aluminum foil (barrier layer) and the tab lead 80 were connected to an insulation resistance tester 90 (manufactured by HIOKI, "3154 DIGITAL MΩ HITESTER"), and a voltage of 25 V was applied, and the resistance value at that time was measured.

[0103] Based on the obtained resistance values, the samples were evaluated according to the following criteria: A: Resistance value greater than 100 MΩ B: Resistance value between 30 MΩ and 100 MΩ C: Resistance value less than 30 MΩ

[0104] -Insulation Test After Heat-Sealing- As shown in Figure 9(A), the measurement sample prepared in the insulation test after heat sealing described above was sealed around the center of an 80 mm edge. The sealing was performed by heating at 180°C and 0.15 MPa for 3 seconds. In Figure 9, reference numeral 50 indicates the sealed portion. Next, as shown in Figure 9(B), the exposed portion of the aluminum foil (barrier layer) and the tab lead 80 were connected to an insulation resistance tester 90 (manufactured by HIOKI, "3154DIGITAL MΩ HITESTER"), and a voltage of 25 V was applied, and the resistance value at that time was measured.

[0105] Based on the obtained resistance values, the samples were evaluated according to the following criteria: A: Resistance value greater than 100 MΩ B: Resistance value between 30 MΩ and 100 MΩ C: Resistance value less than 30 MΩ

[0106] Particle compositions 1 to 4 in the examples and comparative examples are as follows.

[0107]

[0108] In particle compositions 1 to 4, A1 to A2 shown in Table 2 below were used as specific particles A. The material of specific particles A was aluminum silicate.

[0109] In Table 2, the loss on ignition is the amount of loss (mass%) when heated at 860°C for 20 minutes in accordance with JIS K 0667:1992. The apparent specific gravity is a value measured in accordance with JIS K 6220-1:2015. The oil absorption is a value measured in accordance with JIS K 5101-13-2:2004. The whiteness is the Hunter whiteness index. The pH (25°C) is a value measured in accordance with JIS K 5101-17-1:2004. The average particle size is a value measured by the Coulter counter method. The refractive index is a value measured by the liquid immersion method.

[0110]

[0111] The substrate layer constituting the packaging material for an electricity storage device in each of the examples and comparative examples was a single-layer polyamide resin film, and the proportion of polyamide resin in the entire substrate layer was 100 mass %.

[0112] The evaluation results shown in Table 3 reveal the following. It can be seen that the electrical storage device packaging materials of the Examples achieve both improved strength and thinning, and are capable of suppressing curling during molding. On the other hand, it can be seen that the electrical storage device packaging materials of the Comparative Examples are inferior to the Examples in any of the properties of strength, thinning, or curling. It can also be seen that the electrical storage device packaging materials of the Examples, in which the Sdr of the outer surface of the sealant layer is 3% or more, have excellent insulation properties after sealing against impurities.

[0113] The disclosure of Japanese Patent Application No. 2024-148534, filed on August 30, 2024, is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards mentioned herein are incorporated by reference into this specification to the same extent as if each individual document, patent application, and technical standard was specifically and individually indicated to be incorporated by reference.

[0114] REFERENCE SIGNS LIST 1, 10, 20 Electricity storage device exterior material 2 Base material layer 3 Sealant layer 4 Barrier layer 5 Outer adhesive layer 6 Inner adhesive layer 30 Exterior case 37 Flange portion 39 Heat seal portion 100 Electricity storage device 110 Electricity storage device main body

Claims

An exterior material for an electricity storage device, in which a base layer, a barrier layer, and a sealant layer are laminated in this order, The proportion of the polyamide resin in the entire base material layer is 80 mass% or more, The thickness of the substrate layer is 18 μm to 22 μm, the barrier layer has a thickness of 27 μm to 43 μm; The thickness of the sealant layer is 17 μm to 33 μm, the thickness of the entire packaging material for an electricity storage device is 72 μm to 96 μm, The exterior material for an electricity storage device, wherein the sealant layer contains incompatible particles. 　 The packaging material for an electricity storage device according to claim 1 , wherein the barrier layer comprises a metal foil. 　 The packaging material for an electricity storage device according to claim 2 , wherein at least one surface of the metal foil has a chemical conversion coating. 　 The packaging material for an electricity storage device according to claim 1 , wherein the sealant layer contains a propylene resin as a main component.

5. The packaging material for an electricity storage device according to claim 4, wherein the propylene resin has an MFR of 1 g / 10 min to 25 g / 10 min measured under conditions of a temperature of 230° C. and a load of 2.16 kg. 　 The packaging material for an electricity storage device according to claim 1 , wherein the sealant layer comprises an unstretched resin film.

2. The packaging material for an electricity storage device according to claim 1, wherein the X / Y value is 0.45 to 0.75, where X is the thickness of the base layer and Y is the thickness of the barrier layer.

2. The packaging material for an electricity storage device according to claim 1, wherein a Y / Z value is 1.2 to 2.2, where Y is the thickness of the barrier layer and Z is the thickness of the sealant layer. 　 The packaging material for an electricity storage device according to claim 1 , wherein an interfacial developed area ratio Sdr of the outer surface of the sealant layer is 3% or more.

2. The packaging material for an electricity storage device according to claim 1, wherein the incompatible particles have an average particle size of 1 μm to 10 μm.

2. The packaging material for an electricity storage device according to claim 1, wherein the content of the incompatible particles in the sealant layer as a whole is 10,000 ppm by mass to 20,000 ppm by mass. 　　 An outer case for an electricity storage device, which is a molded article of the outer casing material for an electricity storage device according to any one of claims 1 to 11. 　 a power storage device main body; an exterior member that houses the electricity storage device main body and includes the exterior material for an electricity storage device according to any one of claims 1 to 11; A power storage device comprising:

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