Exterior material for energy storage devices, method for manufacturing the same, and energy storage device

Abstract

To provide an exterior material for a power storage device that has a black appearance but has an excellent identification mark printed on its surface in a yellow room.SOLUTION: An exterior material for a power storage device with a black appearance includes a laminate including, in order from the outside, at least a base material layer, a barrier layer, and a heat-fusible resin layer, and the b* value in the L*a*b* color space of the reflected light measured from the outside of the laminate under the measurement conditions of a SCI method, field of view 10°, and light source F2 is -0.20 or less.

Description

[Technical Field]

[0001] This disclosure relates to an exterior material for an energy storage device, a method for manufacturing the same, and an energy storage device. [Background technology]

[0002] While various types of energy storage devices have been developed, casing materials are essential components for sealing the device elements, such as electrodes and electrolytes, in all of them. Traditionally, metal casing materials have been widely used for energy storage devices.

[0003] On the other hand, in recent years, with the increasing performance of electric vehicles, hybrid electric vehicles, personal computers, cameras, and mobile phones, energy storage devices are required to come in a variety of shapes, as well as be thinner and lighter. However, conventional metal casing materials for energy storage devices have the drawback of being unable to keep up with the diversification of shapes, and also having limitations in terms of weight reduction.

[0004] Therefore, in recent years, a film-like laminate in which a base layer, a barrier layer, and a heat-sealable resin layer are sequentially laminated has been proposed as an exterior material for energy storage devices that can be easily processed into various shapes and can achieve thinning and weight reduction (see, for example, Patent Document 1).

[0005] In such an exterior material for energy storage devices, recesses are generally formed by cold forming, and energy storage device elements such as electrodes and electrolytes are placed in the space formed by the recesses. By heat-sealing a heat-sealable resin layer, an energy storage device is obtained in which the energy storage device elements are housed inside the exterior material for the energy storage device. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2008-287971 [Patent Document 2] Japanese Patent Publication No. 2015-166261 [Overview of the project] [Problems that the invention aims to solve]

[0007] For example, energy storage devices such as lithium-ion secondary batteries are sometimes required to be colored black in order to unify the appearance and color with the electrical equipment or other devices to which they are installed (see, for example, Patent Document 2).

[0008] On the other hand, in the manufacturing process of energy storage devices using exterior materials for energy storage devices, identification marks such as product information (for example, letters or numbers displaying lot numbers, barcodes, symbols, etc.) may be printed on the surface of the energy storage device. By attaching identification marks to the surface of the energy storage device, it is possible to distinguish between genuine products and counterfeit products, for example. Similarly, in the manufacturing process of exterior materials for energy storage devices, identification marks may also be printed on the outer surface.

[0009] However, the inventors of this disclosure have found a new problem: when the appearance of energy storage devices or exterior materials for energy storage devices is colored black, the identifiability of printed identification marks and the like decreases during the manufacturing process.

[0010] Specifically, in the manufacturing process of energy storage devices and their casings, processing and inspection are sometimes carried out under yellow light sources, such as in a yellow room. However, it has been found that when identification marks are printed on energy storage devices or their casings, which have a black appearance, and then processed or inspected under the light sources in a yellow room, the legibility of the identification marks decreases, and there is a risk that product information may not be accurately readable.

[0011] Under these circumstances, the primary objective of this disclosure is to provide an exterior material for energy storage devices that, despite having a black appearance, exhibits excellent visibility of identification marks printed on its surface under a light source in a yellow room. [Means for solving the problem]

[0012] The inventors of this disclosure have diligently studied to solve the above-mentioned problems. As a result, in an exterior material for an energy storage device, which is composed of a laminate comprising, in order from the outside, at least a base layer, a barrier layer, and a heat-fusible resin layer, and which has a black appearance, the L of the reflected light measured from the outside under predetermined conditions * a * b * b in color space * By setting the value below a predetermined value, it is possible to adjust the black to exhibit a bluish hue, which is the complementary color of yellow, and we found that this improves the legibility of identification marks printed on the surface, especially in a yellow room or under orange to yellow lamp light sources.

[0013] This disclosure is the result of further consideration based on these findings. Specifically, this disclosure provides inventions in the following embodiments. An exterior material for an energy storage device that has a black appearance, The exterior material for the energy storage device is composed of a laminate comprising, in order from the outside, at least a base layer, a barrier layer, and a heat-sealable resin layer. The L of the reflected light was measured from the outside of the laminate under the measurement conditions of SCI method, field of view 10°, and light source F2. * a * b * b in color space * Exterior material for energy storage devices, with a value of -0.20 or less. [Effects of the Invention]

[0014] According to this disclosure, it is possible to provide an exterior material for energy storage devices that, despite having a black appearance, exhibits excellent visibility of identification marks printed on its surface in a yellow room or under an orange-yellow lamp (Na lamp) light source. Furthermore, according to this disclosure, it is also possible to provide a method for manufacturing the exterior material for energy storage devices and an energy storage device utilizing the exterior material for energy storage devices. [Brief explanation of the drawing]

[0015] [Figure 1] This is a schematic diagram showing an example of the cross-sectional structure of the exterior material for a power storage device of the present disclosure. [Figure 2] This is a schematic diagram showing an example of the cross-sectional structure of the exterior material for a power storage device of the present disclosure. [Figure 3] This is a schematic diagram showing an example of the cross-sectional structure of the exterior material for a power storage device of the present disclosure. [Figure 4] This is a schematic diagram showing an example of the cross-sectional structure of the exterior material for a power storage device of the present disclosure. [Figure 5] This is a schematic diagram showing an example of the cross-sectional structure of the exterior material for a power storage device of the present disclosure. [Figure 6] This is a schematic diagram showing an example of the cross-sectional structure of the exterior material for a power storage device of the present disclosure.

Embodiments for Carrying Out the Invention

[0016] The exterior material for a power storage device of the present disclosure is an exterior material for a power storage device having a black appearance, and the exterior material for a power storage device is composed of a laminate including at least a base material layer, a barrier layer, and a heat-sealable resin layer in order from the outside. Under the measurement conditions of the SCI method, a viewing angle of 10°, and a light source F2, the L of the reflected light measured from the outside * a * b * The b value in the color space * is characterized by being -0.20 or less. According to the exterior material for a power storage device of the present disclosure, by having this configuration, even though it is an exterior material for a power storage device having a black appearance, excellent discriminability of the identification label printed on the surface can be exhibited under the light source in the yellow room.

[0017] Hereinafter, the exterior material for a power storage device of the present disclosure will be described in detail. In this specification, the numerical range indicated by "~" means "or more" and "or less". For example, the notation of 2~15 mm means 2 mm or more and 15 mm or less.

[0018] Furthermore, in the case of the exterior material for energy storage devices described herein, "having a black appearance" means that when the exterior material for energy storage devices is observed from the outside with the naked eye, it is perceived as black. More specifically, "black" in "having a black appearance" refers to CIE1976 L * a * b * (CIELAB) In chromaticity coordinates, L * The value is 40 or less, preferably 35 or less. * Regarding the values, the L of the reflected light was measured from the outside under the measurement conditions of SCI method, field of view 10°, and light source F2. * a * b * This is in the color space. Also, black is L * In addition to the value, a * The value is preferably -20 to +20, and more preferably -10 to +10. In addition to having a black appearance, the exterior material for the energy storage device of this disclosure further b * It is characterized by having a value of -0.20 or less.

[0019] As described below, by adjusting the composition of each layer constituting the exterior material for energy storage devices (layers located outside the barrier layer, such as the base layer, adhesive layer, coloring layer, and surface coating layer), the composition of the layers located outside the barrier layer, and the aging treatment conditions for the exterior material for energy storage devices described below, the appearance of the exterior material for energy storage devices can be made black. * Values ​​can be adjusted. At least a black additive or colorant (e.g., black pigment) can be used. * It is preferable to adjust the value, but to make black by mixing several types of additives and colorants other than black, b * The values ​​may be adjusted. Also, among the layers constituting the exterior material for the energy storage device of this disclosure, one layer may use a black additive or colorant, and the other layers may use an additive or colorant other than black (for example, blue), so that multiple layers can be used. * You may adjust the value.

[0020] Furthermore, a "yellow room" refers to a room where light with wavelengths below 500 nm, including ultraviolet light, is filtered out, and within such a room, light appears yellow. Yellow rooms are commonly set up, for example, in the cleanrooms of semiconductor factories for photolithography processes where photosensitive materials are handled.

[0021] 1. Laminated structure and physical properties of exterior materials for energy storage devices The exterior material 10 for energy storage devices of this disclosure is composed of a laminate comprising, for example, a base layer 1, a barrier layer 3, and a heat-fusible resin layer 4, in that order from the outside, as shown in Figure 1. In the exterior material 10 for energy storage devices, the base layer 1 is the outermost layer, and the heat-fusible resin layer 4 is the innermost layer. When assembling an energy storage device using the exterior material 10 and an energy storage device element, the energy storage device element is housed in a space formed by heat-fussing the peripheral edges of the heat-fusible resin layers 4 of the exterior material 10 facing each other. In the laminate constituting the exterior material 10 for energy storage devices of this disclosure, with respect to the barrier layer 3, the heat-fusible resin layer 4 side is inward of the barrier layer 3, and the base layer 1 side is outward of the barrier layer 3.

[0022] The exterior material 10 for the energy storage device may, for example, have an adhesive layer 2 between the base layer 1 and the barrier layer 3, as shown in Figures 2, 4 to 6, for the purpose of improving the adhesion between these layers (and furthermore, coloring the exterior material 10 for the energy storage device, as described later). Also, as shown in Figures 3 and 4, a coloring layer 21 may be provided between the base layer 1 and the barrier layer 3, as needed, for the purpose of coloring the exterior material 10 for the energy storage device. Also, as shown in Figures 5 and 6, an adhesive layer 5 may be provided between the barrier layer 3 and the heat-fusible resin layer 4, as needed, for the purpose of improving the adhesion between these layers. Furthermore, as shown in Figure 6, a surface coating layer 6 or the like may be provided on the outside of the base layer 1 (opposite the heat-fusible resin layer 4 side), as needed.

[0023] The thickness of the laminate constituting the exterior material 10 for energy storage devices is not particularly limited, but from the viewpoint of cost reduction and improvement of energy density, it is preferably about 180 μm or less, about 155 μm or less, or about 120 μm or less. Furthermore, from the viewpoint of maintaining the function of the exterior material for energy storage devices, which is to protect the energy storage device elements, the thickness of the laminate constituting the exterior material 10 for energy storage devices is preferably about 35 μm or more, about 45 μm or more, or about 60 μm or more. Furthermore, preferred ranges for the thickness of the laminate constituting the exterior material 10 for energy storage devices include, for example, about 35 to 180 μm, about 35 to 155 μm, about 35 to 120 μm, about 45 to 180 μm, about 45 to 155 μm, about 45 to 120 μm, about 60 to 180 μm, about 60 to 155 μm, and about 60 to 120 μm.

[0024] The exterior material 10 for the energy storage device disclosed herein, measured from the outside under the SCI method, field of view 10°, and light source F2, shows the L of the reflected light. * a * b * b in color space * The value is -0.20 or less. * By setting the upper limit of the value to such a specific value, the exterior material for energy storage devices, which has a black appearance, can be adjusted to a black with a bluish hue, which is the complementary color of yellow, and excellent visibility of identification marks printed on the surface can be achieved in a yellow room or under a yellow light source.

[0025] b * The value is not particularly limited, with a limit of -0.20 or less, but from the viewpoint of further improving identifiability and ensuring that the appearance is suitably recognized as black, it is preferably about -0.50 or less, more preferably about -0.80 or less. Also, from a similar viewpoint, b * Preferably, the value is about -5.00 or higher, more preferably about -4.00 or higher, even more preferably about -2.00 or higher, and even more preferably about -1.50 or higher. *Preferred ranges for the value include approximately -5.00 to -0.20, -5.00 to -0.50, -5.00 to -0.80, -4.00 to -0.20, -4.00 to -0.50, -4.00 to -0.80, -2.00 to -0.20, -2.00 to -0.50, -2.00 to -0.80, -1.50 to -0.20, -1.50 to -0.50, and -1.50 to -0.80. Among these, b * A value of approximately -1.50 to -0.80 is particularly preferable.

[0026] Furthermore, the exterior material 10 for the energy storage device of this disclosure, measured from the outside under the measurement conditions of SCI method, field of view 10° and light source F2, shows that the reflected light L * a * b * a in color space * The value is preferably +0.20 or less. This further improves identifiability and ensures that the appearance is preferably black.

[0027] a * In terms of values, from the viewpoint of further improving identifiability and ensuring that the appearance is suitably recognized as black, more preferably values ​​are approximately +0.10 or less, even more preferably +0.04 or less, even more preferably approximately +0.02 or less, even more preferably approximately 0.00 or less, and even more preferably approximately -0.01 or less. Also, from a similar viewpoint, a * Preferably, the value is about -3.50 or higher, more preferably about -3.00 or higher, even more preferably about -2.00 or higher, even more preferably about -0.50 or higher, even more preferably about -0.30 or higher, even more preferably about -0.15 or higher, and even more preferably about -0.10 or higher. *The preferred ranges for the values ​​are approximately -3.50 to +0.20, -3.50 to +0.10, -3.50 to +0.04, -3.50 to +0.02, -3.50 to 0.00, -3.50 to -0.01, -3.00 to +0.20, -3.00 to +0.10, -3.00 to +0.04, and -3.00 to +0.02. degree, -3.00~0.00 degree, -3.00~-0.01 degree, -2.00~+0.20 degree, -2.00~+0.10 degree, -2.00~+0.04 degree, -2.0 0~+0.02, -2.00~0.00, -2.00~-0.01, -0.50~+0.20, -0.50~+0.10, -0.50~+0.0 Around 4, around -0.50~+0.02, around -0.50~0.00, around -0.50~-0.01, around -0.30~+0.20, around -0.30~+0.10, -0 .30~+0.04, -0.30~+0.02, -0.30~0.00, -0.30~-0.01, -0.15~+0.20, -0.15~+0 Examples include approximately 0.10, -0.15 to +0.04, -0.15 to +0.02, -0.15 to 0.00, -0.15 to -0.01, -0.10 to +0.20, -0.10 to +0.10, -0.10 to +0.04, -0.10 to +0.02, -0.10 to 0.00, and -0.10 to -0.01. Among these, a * The values ​​are particularly around -0.30 to -0.01, and -0.10 to -0.01. A certain degree is desirable.

[0028] Furthermore, the exterior material 10 for the energy storage device of this disclosure, measured from the outside under the measurement conditions of SCI method, field of view 10° and light source F2, shows that the reflected light L * a * b * L in color space * The value is preferably 35.0 or less. This further improves identifiability and makes it preferable to recognize that the appearance is black.

[0029] L *In terms of values, from the viewpoint of further improving identifiability and ensuring that the appearance is suitably recognized as black, more preferably, about 33.0 or less, more preferably about 30.0 or less, and even more preferably about 28.0 or less. Also, from the same viewpoint, L * Preferably, the value is about 25.0 or higher, more preferably about 26.0 or higher. Also, L * Preferred ranges for the value include approximately 25.0-35.0, 25.0-33.0, 25.0-30.0, 25.0-28.0, 26.0-35.0, 26.0-33.0, 26.0-30.0, and 26.0-28.0. Among these, L * The values ​​are particularly around 25.0-30.0, 26.0-30.0, and even 26.0 A value of around 29.0, or even better, around 26.0-28.0, is preferable.

[0030] <L * value, a * Value and b * Measurement of values ​​> In this disclosure, L * value, a * Value and b * The values ​​were measured using the following method: For the exterior material of the energy storage device, a spectrophotometer (e.g., Konica Minolta CM-700d) calibrated with a white calibration cap (e.g., CM-A177: Konica Minolta) was set to observation conditions of 10°, observation light source F2, and CSI mode (JIS Z8722-2009), and the L value of the outer (substrate layer side) surface was measured. * a * , b * Measurements will be taken at normal temperature and humidity. Three measurements will be taken for each sample, and the average value will be used as the measurement value. In addition, the outer casing material for the energy storage device will be obtained from the energy storage device, and L will be measured from the outside of the laminate that makes up the outer casing material for the energy storage device. * value, a * value, and b * It is also possible to measure the value. When measuring the exterior material for an energy storage device obtained from an energy storage device, the top surface, which has not been stretched by molding, is the target of measurement.

[0031] In the exterior material for energy storage devices and energy storage devices using the same, examples of printed identification marks include letters and numbers displaying lot numbers, barcodes, and symbols. Furthermore, the ink color used for printing the identification marks (i.e., the color of the identification marks) is preferably white, as this provides excellent identifiability in the exterior material for energy storage devices of the present disclosure, which has a black appearance.

[0032] 2. Each layer forming the exterior material for the energy storage device [Base material layer 1] In this disclosure, the base material layer 1 is a layer provided for purposes such as enabling it to function as a base material for the exterior material of an energy storage device. The base material layer 1 is located on the outer layer side of the exterior material for the energy storage device.

[0033] The material forming the base layer 1 is not particularly limited, as long as it has the function of a base material, that is, at least insulating properties. The base layer 1 can be formed using, for example, a resin, and the resin may contain additives described later. For example, by incorporating additives and colorants described later into the base layer, the above L * value, a * Value and b * You can also adjust the value.

[0034] When the base layer 1 is formed of resin, the base layer 1 may be, for example, a resin film formed of resin, or a film formed by coating with resin. The resin film may be an unstretched film or a stretched film. Examples of stretched films include uniaxially stretched films and biaxially stretched films, with biaxially stretched films being preferred. Examples of stretching methods for forming a biaxially stretched film include sequential biaxial stretching, inflation stretching, and simultaneous biaxial stretching. Examples of resin coating methods include roll coating, gravure coating, and extrusion coating.

[0035] Examples of resins that form the base layer 1 include polyester, polyamide, polyolefin, epoxy resin, acrylic resin, fluororesin, polyurethane, silicon resin, phenolic resin, and modified versions of these resins. Furthermore, the resin forming the base layer 1 may be a copolymer of these resins, or a modified version of such copolymer. It may also be a mixture of these resins.

[0036] Among these, polyester and polyamide are preferred as resins for forming the base layer 1.

[0037] Examples of polyesters include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolymerized polyesters. Examples of copolymerized polyesters include copolymerized polyesters with ethylene terephthalate as the main repeating unit. Specifically, examples include copolymerized polyesters polymerized with ethylene isophthalate using ethylene terephthalate as the main repeating unit (hereinafter abbreviated as polyethylene(terephthalate / isophthalate)), polyethylene(terephthalate / adipate), polyethylene(terephthalate / sodium sulfoisophthalate), polyethylene(terephthalate / sodium isophthalate), polyethylene(terephthalate / phenyl-dicarboxylate), and polyethylene(terephthalate / decanedicarboxylate). These polyesters may be used individually or in combination of two or more types.

[0038] Furthermore, examples of polyamides include aliphatic polyamides such as nylon 6, nylon 66, nylon 610, nylon 12, nylon 46, and copolymers of nylon 6 and nylon 66; hexamethylenediamine-isophthalic acid-terephthalic acid copolymer polyamides such as nylon 6I, nylon 6T, nylon 6IT, and nylon 6I6T (where I represents isophthalic acid and T represents terephthalic acid), which contain constituent units derived from terephthalic acid and / or isophthalic acid; aromatic polyamides such as polyamide MXD6 (polymetaxylylene adipamide); alicyclic polyamides such as polyamide PACM6 (polybis(4-aminocyclohexyl)methaneadipamide); polyamides copolymerized with lactam components or isocyanate components such as 4,4'-diphenylmethane-diisocyanate; polyesteramide copolymers and polyether esteramide copolymers, which are copolymers of copolymerized polyamides with polyester or polyalkylene ether glycol; and other polymers of these polyamides. These polyamides may be used individually or in combination of two or more types.

[0039] The base layer 1 preferably contains at least one of polyester film, polyamide film, and polyolefin film, preferably at least one of stretched polyester film, stretched polyamide film, and stretched polyolefin film, more preferably at least one of stretched polyethylene terephthalate film, stretched polybutylene terephthalate film, stretched nylon film, and stretched polypropylene film, and even more preferably at least one of biaxially oriented polyethylene terephthalate film, biaxially oriented polybutylene terephthalate film, biaxially oriented nylon film, and biaxially oriented polypropylene film.

[0040] The base layer 1 may be a single layer or may consist of two or more layers. If the base layer 1 consists of two or more layers, the base layer 1 may be a laminate formed by laminating resin films with an adhesive, or it may be a laminate of two or more resin films formed by co-extruding resin. Furthermore, the laminate of two or more resin films formed by co-extruding resin may be used as the base layer 1 in its unstretched state, or it may be used as the base layer 1 after uniaxial stretching or biaxial stretching.

[0041] Specific examples of a laminate of two or more resin films in the base layer 1 include a laminate of polyester film and nylon film, a laminate of two or more nylon films, and a laminate of two or more polyester films. Preferably, a laminate of stretched nylon film and stretched polyester film, a laminate of two or more stretched nylon films, and a laminate of two or more stretched polyester films are preferred. For example, when the base layer 1 is a laminate of two resin films, a laminate of polyester resin film and polyester resin film, a laminate of polyamide resin film and polyamide resin film, or a laminate of polyester resin film and polyamide resin film is preferred, and a laminate of polyethylene terephthalate film and polyethylene terephthalate film, a laminate of nylon film and nylon film, or a laminate of polyethylene terephthalate film and nylon film is more preferred. Furthermore, since polyester resin is less likely to discolor when an electrolyte adheres to its surface, for example, when the base layer 1 is a laminate of two or more resin films, it is preferable that the polyester resin film be located in the outermost layer of the base layer 1.

[0042] If the base layer 1 is a laminate of two or more resin films, the two or more resin films may be laminated with an adhesive in between. Preferred adhesives include those similar to those exemplified in adhesive layer 2 described later. The method for laminating the two or more resin films is not particularly limited, and known methods can be used, such as dry lamination, sandwich lamination, extrusion lamination, and thermal lamination, with dry lamination being preferred. When laminating by dry lamination, it is preferable to use a polyurethane adhesive. In this case, the thickness of the adhesive is, for example, about 2 to 5 μm. Alternatively, an anchor coat layer may be formed on the resin film and then laminated. The anchor coat layer is similar to the adhesive exemplified in adhesive layer 2 described later. In this case, the thickness of the anchor coat layer is, for example, about 0.01 to 1.0 μm.

[0043] Furthermore, at least one of the surface and interior of the base layer 1 may contain additives such as lubricants, flame retardants, antiblocking agents, antioxidants, light stabilizers, tackifiers, and antistatic agents. Only one type of additive may be used, or two or more types may be mixed and used.

[0044] In this disclosure, from the viewpoint of improving the moldability of the exterior material for energy storage devices, it is preferable that a lubricant be present on the surface of the base layer 1. The lubricant is not particularly limited, but amide lubricants are preferred. Specific examples of amide lubricants include saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, methylolamides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, fatty acid ester amides, and aromatic bisamides. Specific examples of saturated fatty acid amides include lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, and hydroxystearic acid amide. Specific examples of unsaturated fatty acid amides include oleic acid amide and erucic acid amide. Specific examples of substituted amides include N-oleyl palmitic acid amide, N-stearyl stearate amide, N-stearyl oleic acid amide, N-oleyl stearate amide, and N-stearyl erucic acid amide. Specific examples of methylolamides include methylol stearate amide. Specific examples of saturated fatty acid bisamides include methylenebisstearate, ethylenebiscaprate, ethylenebislaurate, ethylenebisstearate, ethylenebishydroxystearate, ethylenebisbehenamide, hexamethylenebisstearate, hexamethylenebisbehenamide, hexamethylenehydroxystearate, N,N'-distearyladipamide, and N,N'-distearylsebacinamide. Specific examples of unsaturated fatty acid bisamides include ethylenebisoleamide, ethylenebiserucamide, hexamethylenebisoleamide, N,N'-dioleyladipamide, and N,N'-dioleylsebacinamide. Specific examples of fatty acid ester amides include stearamidoethylstearate. Specific examples of aromatic bisamides include m-xylylenebisstearate, m-xylylenebishydroxystearate, and N,N'-distearyl isophthalamide. The lubricant may be used alone or in combination of two or more types.

[0045] If a lubricant is present on the surface of the substrate layer 1, the amount present is not particularly limited, but preferably about 3 mg / m². 2 More preferably 4-15 mg / m² 2 To a certain extent, more preferably 5-14 mg / m² 2 The degree can be described as follows.

[0046] The lubricant present on the surface of the base layer 1 may be a lubricant contained in the resin constituting the base layer 1 that has seeped out, or a lubricant may be applied to the surface of the base layer 1.

[0047] The thickness of the base layer 1 is not particularly limited as long as it performs its function as a base material, but for example, it can be about 3 to 50 μm, preferably about 10 to 35 μm. If the base layer 1 is a laminate of two or more resin films, the thickness of each resin film constituting each layer can be preferably about 2 to 25 μm.

[0048] For example, if the adhesive layer is a black-colored layer, it is preferable that the substrate layer located outside the adhesive layer be transparent or translucent.

[0049] [Adhesive layer 2] In the exterior material for energy storage devices of this disclosure, the adhesive layer 2 is a layer provided between the substrate layer 1 and the barrier layer 3 as needed, for the purpose of improving the adhesion between them.

[0050] Furthermore, in the exterior material for energy storage devices of this disclosure, the adhesive layer 2 may be colored black. By coloring the adhesive layer 2 black, the exterior material for energy storage devices has a black appearance, and then the above b * The value can be preferably set to -0.20 or less. However, if the adhesive layer 2 is colored black, then the above b *The value will not be less than -0.20. By adjusting the composition of the adhesive layer 2, such as the type and amount of coloring agent contained in it, the composition of the base layer 1, the surface coating layer 6 and coloring layer 21 which are located outside the barrier layer 3, and the aging treatment conditions for the exterior material for the energy storage device described later, the appearance of the exterior material for the energy storage device can be made black, and the above b * The value can be set to -0.20 or less. * Value and a * The same applies to setting values.

[0051] The adhesive layer 2 is formed by an adhesive capable of bonding the substrate layer 1 and the barrier layer 3. The adhesive used to form the adhesive layer 2 is not limited, but may be a chemical reaction type, solvent evaporation type, heat melt type, hot pressure type, etc. It may also be a two-component curing adhesive (two-part adhesive), a one-component curing adhesive (one-part adhesive), or a resin that does not undergo a curing reaction. Furthermore, the adhesive layer 2 may be a single layer or a multi-layer layer.

[0052] Specifically, adhesive components included in adhesives include polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, copolymerized polyester; polyethers; polyurethanes; epoxy resins; phenolic resins; polyamides such as nylon 6, nylon 66, nylon 12, copolymerized polyamides; polyolefin resins such as polyolefins, cyclic polyolefins, acid-modified polyolefins, and acid-modified cyclic polyolefins; polyvinyl acetate; cellulose; (meth)acrylic resins; polyimides; polycarbonates; amino resins such as urea resins and melamine resins; rubbers such as chloroprene rubber, nitrile rubber, and styrene-butadiene rubber; and silicone resins. These adhesive components may be used individually or in combination of two or more. Among these adhesive components, polyurethane adhesives are particularly preferred. Furthermore, the adhesive strength of these adhesive resins can be increased by using an appropriate curing agent. The curing agent is selected appropriately from polyisocyanates, polyfunctional epoxy resins, oxazoline group-containing polymers, polyamine resins, acid anhydrides, etc., depending on the functional groups of the adhesive components.

[0053] Examples of polyurethane adhesives include polyurethane adhesives comprising a main component containing a polyol compound and a curing agent containing an isocyanate compound. Preferably, two-component curing type polyurethane adhesives are used, with a polyol such as polyester polyol, polyether polyol, and acrylic polyol as the main component and an aromatic or aliphatic polyisocyanate as the curing agent. Furthermore, it is preferable to use a polyester polyol as the polyol compound, which has hydroxyl groups not only at the terminals of the repeating units but also in the side chains. Examples of curing agents include aliphatic, alicyclic, aromatic, and aromaticaliphatic isocyanate compounds. Examples of isocyanate compounds include hexamethylene diisocyanate (HDI), xylylene diisocyanate (XDI), isophorone diisocyanate (IPDI), hydrogenated XDI (H6XDI), hydrogenated MDI (H12MDI), tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), and naphthalene diisocyanate (NDI). Furthermore, examples include polyfunctional isocyanate modified products derived from one or more of these diisocyanates. Polyisocyanate compounds can also be used as polymers (e.g., trimers). Such polymers include adducts, biuretes, and nurates. Note that aliphatic isocyanate compounds refer to isocyanates having aliphatic groups and no aromatic rings, alicyclic isocyanate compounds refer to isocyanates having alicyclic hydrocarbon groups, and aromatic isocyanate compounds refer to isocyanates having aromatic rings. The adhesive layer 2 is formed from a polyurethane adhesive, which provides excellent electrolyte resistance to the exterior material for energy storage devices, preventing peeling of the base layer 1 even if electrolyte adheres to the sides.

[0054] Furthermore, the adhesive layer 2 may contain other components as long as they do not impair adhesion, and may include colorants, thermoplastic elastomers, tackifiers, fillers, etc. The inclusion of a colorant in the adhesive layer 2 allows for the coloring of the exterior material for energy storage devices. Known colorants such as pigments and dyes can be used. Additionally, only one type of colorant may be used, or two or more types may be mixed.

[0055] The type of pigment is as described in b above. * The value is -0.20 or less and is not limited as long as it does not impair the adhesion of adhesive layer 2. Examples of organic pigments include azo, phthalocyanine, quinacridone, anthraquinone, dioxazine, indigothioindigo, perinone-perylene, isoindorenine, and benzimidazolon pigments. Examples of inorganic pigments include carbon black, titanium, titanium dioxide, cadmium, lead, chromium oxide, and iron pigments. Other examples include fine mica powder and fish scale foil.

[0056] The average particle size of the pigment is as follows: * As long as the value is -0.20 or less and the adhesion of adhesive layer 2 is not impaired, there are no particular limitations, for example, a value of about 0.05 to 5 μm, preferably about 0.08 to 2 μm. The average particle size of the pigment is the median diameter measured by a laser diffraction / scattering particle size distribution analyzer. Note that if the primary particle size of the pigment changes, even with the same type of pigment, the above L * value, a * Value and b * The value changes. For example, if the primary particle size of the black pigment increases, it may result in a slightly bluish black color. For this reason, in this disclosure, L * value, a * Value and b *In setting the values, it is also preferable to adjust the primary particle size of the pigment used. Preferably, the secondary particle size of the pigment is about 0.8 μm or less, more preferably about 0.6 μm or less, and even more preferably about 0.4 μm or less. Furthermore, preferably, the secondary particle size of the pigment is about 0.05 μm or more, more preferably about 0.1 μm or more. Preferred ranges for the secondary particle size of the pigment include about 0.05 to 0.8 μm, about 0.05 to 0.6 μm, about 0.05 to 0.4 μm, about 0.1 to 0.8 μm, about 0.1 to 0.6 μm, and about 0.1 to 0.4 μm.

[0057] Among colorants, it is preferable to use a blackening agent to give the exterior material of an energy storage device a black appearance. A blackening agent is an additive such as a pigment or dye that can color a material black, and is a black coloring agent. Examples of blackening agents include black pigments. Among black pigments, carbon and titanium-based pigments are preferred. Black pigments made of carbon are generally called carbon black. Among titanium-based pigments, titanium black is preferred. Alternatively, carbon black and titanium black may be mixed and used.

[0058] Furthermore, the exterior material for the energy storage device is made black, and the above b * From the viewpoint of improving identifiability by preferably setting the value to -0.20 or less, it is preferable that the adhesive layer 2 further contains a blue agent in addition to the black agent. The blue agent is an additive such as a pigment or dye that can be colored blue, and is a blue coloring agent. Examples of blue agents include dyes such as anthraquinone and indigoid, and pigments such as phthalocyanine, ultramarine, ferric ferrocyanide, and Prussian blue. Examples of phthalocyanine include copper phthalocyanine and metal-free phthalocyanine, with copper phthalocyanine being preferred. Copper phthalocyanine is known as a blue pigment.

[0059] When analyzing the laminate constituting the exterior material for energy storage devices of this disclosure using X-ray fluorescence analysis (XRF) from the outside, it is preferable that the element Cu is detected. For example, if the adhesive layer 2 of the exterior material for energy storage devices contains a copper-containing pigment (e.g., copper phthalocyanine) as its pigment, the element Cu will be detected when analyzing the laminate from the outside using X-ray fluorescence analysis (XRF). As described later, even when the surface coating layer 6 or the coloring layer 21 contains a copper-containing pigment (e.g., copper phthalocyanine), the element Cu will be detected when analyzing the laminate from the outside using X-ray fluorescence analysis (XRF). The measurement conditions described in the examples can be used for detecting the element Cu by X-ray fluorescence analysis (XRF).

[0060] The content of the coloring agent in the adhesive layer 2 is such that the exterior material for the energy storage device is colored black, and the above b * The value is not particularly limited as long as it is -0.20 or less, but from the viewpoint of appropriate coloring, it is preferably about 0.5% by mass or more, more preferably about 1.0% by mass or more. Furthermore, from the viewpoint of appropriately maintaining adhesion between the substrate layer 1 and the barrier layer 3, the content of the colorant in the adhesive layer 2 is preferably about 50.0% by mass or less, more preferably about 30.0% by mass or less, and even more preferably 20.0% by mass or less. Preferred ranges for the content of the colorant in the adhesive layer 2 include about 0.5 to 50.0% by mass, about 0.5 to 30.0% by mass, about 0.5 to 20.0% by mass, about 1.0 to 50.0% by mass, about 1.0 to 30.0% by mass, and about 1.0 to 20.0% by mass.

[0061] Furthermore, when a blackening agent is incorporated as a coloring agent into the adhesive layer 2, the amount of blackening agent in the adhesive layer 2 is such that the exterior material for the energy storage device is colored black, as described above b *The value is not particularly limited as long as it is -0.20 or less, and from the viewpoint of appropriate coloring, it is preferably about 0.5% by mass or more, more preferably about 1.0% by mass or more. Furthermore, from the viewpoint of appropriately maintaining adhesion between the substrate layer 1 and the barrier layer 3, the content of the blackening agent in the adhesive layer 2 is preferably about 50.0% by mass or less, more preferably about 30.0% by mass or less, and even more preferably 20.0% by mass or less. Furthermore, preferred ranges for the content of the blackening agent in the adhesive layer 2 include about 0.5 to 50.0% by mass, about 0.5 to 30.0% by mass, about 0.5 to 20.0% by mass, about 1.0 to 50.0% by mass, about 1.0 to 30.0% by mass, and about 1.0 to 20.0% by mass. Furthermore, when a blue coloring agent is incorporated into the adhesive layer 2, the content of the blue coloring agent in the adhesive layer 2 is not particularly limited as long as the exterior material for the energy storage device is colored black, and for example, it is about 0.5 to 30% by mass, preferably 1 to 20% by mass.

[0062] Furthermore, when a black agent and a blue agent are blended into the adhesive layer 2, the ratio of the black agent to the blue agent in the adhesive layer 2 is such that the black agent is 100 parts by mass, and the blue agent is preferably about 0.1 parts by mass or more, more preferably about 1 part by mass or more, and even more preferably about 10 parts by mass or more. The blue agent is preferably about 150 parts by mass or less, and more preferably about 100 parts by mass or less. The preferred range for the blue agent is about 0.1 to 150 parts by mass, about 0.1 to 100 parts by mass, about 1 to 150 parts by mass, about 1 to 100 parts by mass, about 10 to 150 parts by mass, and about 10 to 100 parts by mass. As mentioned above, by adjusting the primary particle size of the pigment used, the composition of the layer located outside the barrier layer 3, and the aging treatment conditions of the exterior material for the energy storage device described later, L * value, a * Value and b * Since the values ​​can be set, the adhesive layer 2 may contain only a black coloring agent, and may not contain, for example, a blue coloring agent.

[0063] The thickness of the adhesive layer 2 is not particularly limited as long as the base material layer 1 and the barrier layer 3 can be adhered. For example, it is about 1 μm or more, about 2 μm or more. Also, the thickness of the adhesive layer 2 is, for example, about 10 μm or less, about 5 μm or less. Preferred ranges for the thickness of the adhesive layer 2 include about 1 to 10 μm, about 1 to 5 μm, about 2 to 10 μm, and about 2 to 5 μm.

[0064] [Coloring layer 21] The coloring layer 21 is a layer provided between the base material layer 1 and the barrier layer 3 as needed. When having the adhesive layer 2, the coloring layer 21 may be provided on at least one of the base material layer 1 and the adhesive layer 2, and between the adhesive layer 2 and the barrier layer 3. Also, the coloring layer 21 may be provided outside the base material layer 1. By providing the coloring layer 21, the exterior material for the power storage device can be suitably colored black.

[0065] Further, in the exterior material for the power storage device of the present disclosure, by coloring the coloring layer 21 black, after making the exterior material for the power storage device have a black appearance, the b * value can be suitably set to -0.20 or less. However, similar to the case of coloring the aforementioned adhesive layer 2 black, simply coloring the coloring layer 21 black does not necessarily make the b * value -0.20 or less. By adjusting the composition such as the type and content of the coloring agent contained in the coloring layer 21, the composition of the layer located outside the barrier layer 3 such as the base material layer 1, the surface coating layer 6 provided as needed, and the adhesive layer 2, and further, the aging treatment conditions of the exterior material for the power storage device described later, the exterior of the exterior material for the power storage device can be made black and the b * value can be set to -0.20 or less. The setting of the L * value and the a * value is the same.

[0066] The coloring layer 21 can be formed, for example, by applying an ink containing a coloring agent to the surface of the base material layer 1 or the surface of the barrier layer 3. As the coloring agent, known ones such as pigments and dyes can be used. Also, only one type of coloring agent may be used, or two or more types may be mixed and used.

[0067] Specific examples of colorants included in the colored layer 21 are the same as those exemplified in the [adhesive layer 2] section.

[0068] The amount of coloring agent in the colored layer 21 is such that the exterior material for the energy storage device is colored black, as described above. * The value is not particularly limited as long as it is -0.20 or less, but from the viewpoint of proper coloring, it is preferably about 0.5% by mass or more, more preferably about 1.0% by mass or more. Furthermore, from the viewpoint of properly forming the colored layer 21, the content of the coloring agent in the colored layer 21 is preferably about 50.0% by mass or less, more preferably about 30.0% by mass or less, and even more preferably 20.0% by mass or less. Preferred ranges for the content of the coloring agent in the colored layer 21 include about 0.5 to 50.0% by mass, about 0.5 to 30.0% by mass, about 0.5 to 20.0% by mass, about 1.0 to 50.0% by mass, about 1.0 to 30.0% by mass, and about 1.0 to 20.0% by mass.

[0069] Furthermore, when a blackening agent is incorporated into the colored layer 21, the amount of blackening agent in the colored layer 21 is such that the exterior material for the energy storage device is colored black, as described above. * The value is not particularly limited as long as it is -0.20 or less, and from the viewpoint of appropriate coloring, it is preferably about 0.5% by mass or more, more preferably about 1.0% by mass or more. Furthermore, from the viewpoint of appropriately forming the colored layer 21, the content of the black agent in the colored layer 21 is preferably about 50.0% by mass or less, more preferably about 30.0% by mass or less, and even more preferably 20.0% by mass or less. Preferred ranges for the content of the black agent in the colored layer 21 include about 0.5 to 50.0% by mass, about 0.5 to 30.0% by mass, about 0.5 to 20.0% by mass, about 1.0 to 50.0% by mass, about 1.0 to 30.0% by mass, and about 1.0 to 20.0% by mass. Furthermore, when a blue agent is blended into the colored layer 21, the content of the blue agent in the colored layer 21 is not particularly limited as long as the exterior material for the energy storage device is colored black, and for example, it is about 0.5 to 30% by mass, preferably 1 to 20% by mass.

[0070] Furthermore, when a black agent and a blue agent are blended in the colored layer 21, the ratio of the black agent to the blue agent in the colored layer 21 is such that the black agent is 100 parts by mass, and the proportion of the blue agent is preferably about 0.1 parts by mass or more, more preferably about 1 part by mass or more, and even more preferably about 10 parts by mass or more. The proportion of the blue agent is preferably about 150 parts by mass or less, and more preferably about 100 parts by mass or less. The preferred range for the blue agent is about 0.1 to 150 parts by mass, about 0.1 to 100 parts by mass, about 1 to 150 parts by mass, about 1 to 100 parts by mass, about 10 to 150 parts by mass, and about 10 to 100 parts by mass.

[0071] [Barrier layer 3] In the exterior material for energy storage devices, the barrier layer 3 is a layer that at least prevents the intrusion of moisture.

[0072] Examples of barrier layer 3 include metal foil, vapor-deposited film, and resin layer with barrier properties. Examples of vapor-deposited films include metal vapor-deposited films, inorganic oxide vapor-deposited films, and carbon-containing inorganic oxide vapor-deposited films. Examples of resin layers include fluorine-containing resins such as polymers mainly composed of polyvinylidene chloride, chlorotrifluoroethylene (CTFE), polymers mainly composed of tetrafluoroethylene (TFE), polymers having fluoroalkyl groups, and polymers mainly composed of fluoroalkyl units, as well as ethylene vinyl alcohol copolymers. In addition, a resin film having at least one of these vapor-deposited films and resin layers can also be provided as barrier layer 3. Multiple layers of barrier layer 3 may be provided. It is preferable that barrier layer 3 includes a layer made of a metal material. Specific examples of metal materials constituting barrier layer 3 include aluminum alloy, stainless steel, titanium steel, and steel plates. When used as a metal foil, it is preferable that it includes at least one of aluminum alloy foil and stainless steel foil.

[0073] From the viewpoint of improving the formability of the exterior material for energy storage devices, the aluminum alloy foil is more preferably a soft aluminum alloy foil composed of, for example, an annealed aluminum alloy, and from the viewpoint of further improving formability, it is more preferably an aluminum alloy foil containing iron. In an iron-containing aluminum alloy foil (100% by mass), the iron content is preferably 0.1 to 9.0% by mass, and more preferably 0.5 to 2.0% by mass. By having an iron content of 0.1% by mass or more, an exterior material for energy storage devices with better formability can be obtained. By having an iron content of 9.0% by mass or less, an exterior material for energy storage devices with better flexibility can be obtained. Examples of soft aluminum alloy foils include aluminum alloy foils having compositions specified in JIS H4160:1994 A8021H-O, JIS H4160:1994 A8079H-O, JIS H4000:2014 A8021P-O, or JIS H4000:2014 A8079P-O. Silicon, magnesium, copper, manganese, etc., may also be added as needed. Softening can be achieved through annealing or other treatments.

[0074] Furthermore, examples of stainless steel foils include austenitic, ferritic, austenitic-ferritic, martensitic, and precipitation-hardening stainless steel foils. Moreover, from the viewpoint of providing an exterior material for energy storage devices with excellent formability, it is preferable that the stainless steel foil be made of austenitic stainless steel.

[0075] Specific examples of austenitic stainless steels that make up stainless steel foil include SUS304, SUS301, and SUS316L, with SUS304 being particularly preferred among these.

[0076] In the case of metal foil, the thickness of the barrier layer 3 should at least function as a barrier layer that prevents moisture from penetrating, for example, about 9 to 200 μm. The thickness of the barrier layer 3 is preferably about 85 μm or less, more preferably about 50 μm or less, even more preferably about 40 μm or less, and particularly preferably about 35 μm or less. Also, the thickness of the barrier layer 3 is preferably about 10 μm or more, even more preferably about 20 μm or more, and more preferably about 25 μm or more. Preferred ranges for the thickness include about 10 to 85 μm, about 10 to 50 μm, about 10 to 40 μm, about 10 to 35 μm, about 20 to 85 μm, about 20 to 50 μm, about 20 to 40 μm, about 20 to 35 μm, about 25 to 85 μm, about 25 to 50 μm, about 25 to 40 μm, and about 25 to 35 μm. When the barrier layer 3 is made of aluminum alloy foil, the above range is particularly preferred. Furthermore, when the barrier layer 3 is made of stainless steel foil, the thickness of the stainless steel foil is preferably about 60 μm or less, more preferably about 50 μm or less, even more preferably about 40 μm or less, even more preferably about 30 μm or less, and particularly preferably about 25 μm or less. Furthermore, the thickness of the stainless steel foil is preferably about 10 μm or more, more preferably about 15 μm or more. Furthermore, preferred thickness ranges for the stainless steel foil include about 10 to 60 μm, about 10 to 50 μm, about 10 to 40 μm, about 10 to 30 μm, about 10 to 25 μm, about 15 to 60 μm, about 15 to 50 μm, about 15 to 40 μm, about 15 to 30 μm, and about 15 to 25 μm.

[0077] Furthermore, if the barrier layer 3 is a metal foil, it is preferable to provide a corrosion-resistant coating on at least the side opposite to the substrate layer to prevent dissolution and corrosion. The barrier layer 3 may also have a corrosion-resistant coating on both sides. Here, a corrosion-resistant coating refers to a thin film that provides corrosion resistance to the barrier layer by performing a corrosion prevention treatment on the surface of the barrier layer, such as a hot water modification treatment like boehmite treatment, a chemical conversion treatment, anodizing treatment, plating treatment with nickel or chromium, or coating agent application. One type of treatment may be performed to form the corrosion-resistant coating, or two or more types may be combined. In addition, it is possible to have multiple layers instead of just one. Furthermore, among these treatments, hot water modification treatment and anodizing treatment are treatments that dissolve the surface of the metal foil with a treatment agent and form a metal compound with excellent corrosion resistance. Note that these treatments may also be included in the definition of chemical conversion treatment. Also, if the barrier layer 3 has a corrosion-resistant coating, the barrier layer 3 includes the corrosion-resistant coating.

[0078] The corrosion-resistant coating prevents delamination between the barrier layer (e.g., aluminum alloy foil) and the base layer during the molding of exterior materials for energy storage devices. It also prevents dissolution and corrosion of the barrier layer surface due to hydrogen fluoride generated by the reaction of electrolyte and water, particularly the dissolution and corrosion of aluminum oxide present on the barrier layer surface when the barrier layer is aluminum alloy foil. Furthermore, it improves the adhesion (wettability) of the barrier layer surface, preventing delamination between the base layer and the barrier layer during heat sealing and molding.

[0079] Various corrosion-resistant coatings are known to be formed by chemical conversion treatments, mainly including corrosion-resistant coatings containing at least one of the following: phosphates, chromates, fluorides, triazinethiol compounds, and rare earth oxides. Examples of chemical conversion treatments using phosphates and chromates include chromate treatment, phosphate chromate treatment, phosphate-chromate treatment, and chromate treatment. Examples of chromium compounds used in these treatments include chromium nitrate, chromium fluoride, chromium sulfate, chromium acetate, chromium oxalate, chromium biphosphate, acetyl acetate chromate, chromium chloride, and potassium chromium sulfate. Examples of phosphorus compounds used in these treatments include sodium phosphate, potassium phosphate, ammonium phosphate, and polyphosphate. Examples of chromate treatments include etching chromate treatment, electrolytic chromate treatment, and coating-type chromate treatment, with coating-type chromate treatment being preferred. This coating-type chromate treatment involves first degreasing at least the inner surface of a barrier layer (e.g., aluminum alloy foil) using a well-known treatment method such as alkaline immersion, electrolytic cleaning, acid cleaning, electrolytic acid cleaning, or acid activation. Then, a treatment solution mainly composed of metal phosphate salts such as chromium phosphate, titanium phosphate, zirconium phosphate, and zinc phosphate, or mixtures thereof, or a treatment solution mainly composed of nonmetallic phosphates and mixtures thereof, or a treatment solution consisting of a mixture of these with synthetic resins, etc., is applied to the degreased surface using a well-known coating method such as roll coating, gravure printing, or immersion, and then dried. Various solvents can be used as the treatment solution, such as water, alcohol-based solvents, hydrocarbon-based solvents, ketone-based solvents, ester-based solvents, and ether-based solvents, with water being preferred. Furthermore, examples of resin components used in this process include polymers such as phenolic resins and acrylic resins, and examples of chromate treatment using an amination phenol polymer having repeating units represented by the following general formulas (1) to (4). In this amination phenol polymer, the repeating units represented by the following general formulas (1) to (4) may be included individually or in any combination of two or more types.The acrylic resin is preferably a derivative such as polyacrylic acid, an acrylic acid-methacrylic acid ester copolymer, an acrylic acid-maleic acid copolymer, an acrylic acid-styrene copolymer, or their sodium salts, ammonium salts, amine salts, etc. Particularly preferred are derivatives of polyacrylic acid such as ammonium salts, sodium salts, or amine salts of polyacrylic acid. In the present disclosure, polyacrylic acid means a polymer of acrylic acid. Also, the acrylic resin is preferably a copolymer of acrylic acid and a dicarboxylic acid or dicarboxylic anhydride, and is also preferably an ammonium salt, sodium salt, or amine salt of a copolymer of acrylic acid and a dicarboxylic acid or dicarboxylic anhydride. The acrylic resin may be used alone or in combination of two or more.

[0080]

Chemical formula

[0081]

Chemical formula

[0082]

Chemical formula

[0083]

Chemical formula

[0084] In general formulas (1) to (4), X represents a hydrogen atom, a hydroxy group, an alkyl group, a hydroxyalkyl group, an allyl group or a benzyl group. Also, R 1 and R 2 each independently represent the same or different hydroxy group, alkyl group, or hydroxyalkyl group. In general formulas (1) to (4), X, R 1 and R 2Examples of alkyl groups represented by include linear or branched alkyl groups having 1 to 4 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, and tert-butyl groups. Also, X, R 1 and R 2 Examples of hydroxyalkyl groups represented by include linear or branched alkyl groups having 1 to 4 carbon atoms with one hydroxyl group substituted, such as hydroxymethyl group, 1-hydroxyethyl group, 2-hydroxyethyl group, 1-hydroxypropyl group, 2-hydroxypropyl group, 3-hydroxypropyl group, 1-hydroxybutyl group, 2-hydroxybutyl group, 3-hydroxybutyl group, and 4-hydroxybutyl group. In general formulas (1) to (4), X and R 1 and R 2 The alkyl group and hydroxyalkyl group shown may be the same or different. In general formulas (1) to (4), X is preferably a hydrogen atom, a hydroxyl group, or a hydroxyalkyl group. The number-average molecular weight of the amination phenol polymer having repeating units represented by general formulas (1) to (4) is preferably about 500 to 1,000,000, and more preferably about 1,000 to 20,000. The amination phenol polymer is produced, for example, by polycondensing a phenol compound or naphthol compound with formaldehyde to produce a polymer consisting of repeating units represented by the above general formula (1) or general formula (3), and then adding formaldehyde and amine (R 1 R 2 Using NH) to form the functional group (-CH2NR 1 R 2 It is produced by introducing ) into the polymer obtained above. The amination phenol polymer can be used alone or in a mixture of two or more types.

[0085] Another example of a corrosion-resistant coating is a thin film formed by a coating-type corrosion prevention treatment, which involves applying a coating agent containing at least one selected from the group consisting of rare earth element oxide sols, anionic polymers, and cationic polymers. The coating agent may further contain phosphoric acid or phosphate, and a crosslinking agent for crosslinking the polymer. In the rare earth element oxide sol, fine particles of rare earth element oxides (for example, particles with an average particle size of 100 nm or less) are dispersed in a liquid dispersion medium. Examples of rare earth element oxides include cerium oxide, yttrium oxide, neodymium oxide, and lanthanum oxide, with cerium oxide being preferred from the viewpoint of further improving adhesion. The rare earth element oxides contained in the corrosion-resistant coating can be used individually or in combination of two or more. Various solvents can be used as the liquid dispersion medium for the rare earth element oxide sol, such as water, alcohol-based solvents, hydrocarbon-based solvents, ketone-based solvents, ester-based solvents, and ether-based solvents, with water being preferred. Preferred cationic polymers include, for example, polyethyleneimine, ionic polymer complexes comprising polyethyleneimine and a polymer having a carboxylic acid, primary amine-grafted acrylic resins obtained by graft polymerization of a primary amine onto an acrylic main skeleton, polyallylamine or its derivatives, and amination phenols. Preferred anionic polymers are poly(meth)acrylic acid or its salts, or copolymers mainly composed of (meth)acrylic acid or its salts. Furthermore, the crosslinking agent is preferably at least one selected from the group consisting of a compound having one of the functional groups of isocyanate, glycidyl, carboxyl, or oxazoline, and a silane coupling agent. Additionally, the phosphoric acid or phosphate is preferably condensed phosphoric acid or condensed phosphate.

[0086] An example of a corrosion-resistant coating is one formed by dispersing metal oxides such as aluminum oxide, titanium oxide, cerium oxide, and tin oxide, or fine particles of barium sulfate, in phosphoric acid, applying this mixture to the surface of a barrier layer, and then baking it at a temperature of 150°C or higher.

[0087] The corrosion-resistant coating may, if necessary, be a laminated structure in which at least one of a cationic polymer and an anionic polymer is further laminated. Examples of cationic and anionic polymers include those mentioned above.

[0088] Furthermore, the composition of the corrosion-resistant coating can be analyzed, for example, using time-of-flight secondary ion mass spectrometry.

[0089] The amount of corrosion-resistant film to be formed on the surface of the barrier layer 3 in the chemical conversion treatment is not particularly limited, but for example, in the case of coating-type chromate treatment, the surface of the barrier layer 3 is 1 m 2 It is desirable that the product contains, for example, about 0.5 to 50 mg of chromium-based chromium, preferably about 1.0 to 40 mg of phosphorus-based chromium

[0090] The thickness of the corrosion-resistant coating is not particularly limited, but from the viewpoint of the cohesive force of the coating and the adhesion force with the barrier layer and the heat-fusible resin layer, it is preferably about 1 nm to 20 μm, more preferably about 1 nm to 100 nm, and even more preferably about 1 nm to 50 nm. The thickness of the corrosion-resistant coating can be measured by observation with a transmission electron microscope, or by a combination of observation with a transmission electron microscope and energy-dispersive X-ray spectroscopy or electron beam energy loss spectroscopy. By analyzing the composition of the corrosion-resistant coating using time-of-flight secondary ion mass spectrometry, for example, secondary ions consisting of Ce, P, and O (e.g., Ce2PO4) can be identified. + , C epo4 - (at least one of the above), or, for example, a secondary ion consisting of Cr, P, and O (e.g., CrPO2) + , CrPO4 - Peaks originating from at least one of the following are detected.

[0091] The chemical conversion treatment is carried out by applying a solution containing compounds used to form a corrosion-resistant film to the surface of the barrier layer using methods such as bar coating, roll coating, gravure coating, or immersion, and then heating the barrier layer to a temperature of approximately 70-200°C. Alternatively, before applying the chemical conversion treatment to the barrier layer, it may be subjected to a degreasing treatment using methods such as alkaline immersion, electrolytic cleaning, acid cleaning, or electrolytic acid cleaning. This degreasing treatment makes it possible to perform the chemical conversion treatment on the surface of the barrier layer more efficiently. Furthermore, by using an acid degreasing agent, which is a fluorine-containing compound dissolved in an inorganic acid, it is possible to not only degrease the metal foil but also form a fluoride of the passive metal; in such cases, only the degreasing treatment may be performed.

[0092] [Thermal adhesive resin layer 4] In the exterior material for energy storage devices of this disclosure, the heat-sealable resin layer 4 is the innermost layer and is a layer (sealant layer) that performs the function of sealing the energy storage device elements by heat-sealing the heat-sealable resin layers together during the assembly of the energy storage device.

[0093] The resin constituting the heat-fusible resin layer 4 is not particularly limited as long as it is heat-fusible, but resins containing a polyolefin backbone, such as polyolefins and acid-modified polyolefins, are preferred. The presence of a polyolefin backbone in the resin constituting the heat-fusible resin layer 4 can be analyzed, for example, by infrared spectroscopy or gas chromatography-mass spectrometry. Furthermore, when the resin constituting the heat-fusible resin layer 4 is analyzed by infrared spectroscopy, it is preferable to detect a peak originating from maleic anhydride. For example, when maleic anhydride-modified polyolefin is measured by infrared spectroscopy, a peak originating from maleic anhydride is detected at wavenumber 1760 cm⁻¹. -1 Nearby wave frequency 1780cm -1 A peak derived from maleic anhydride is detected in the vicinity. If the heat-fusible resin layer 4 is composed of maleic anhydride-modified polyolefin, a peak derived from maleic anhydride will be detected when measured by infrared spectroscopy. However, if the degree of acid modification is low, the peak may become small and not be detected. In that case, analysis is possible by nuclear magnetic resonance spectroscopy.

[0094] Examples of polyolefins include polyethylene such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; ethylene-α-olefin copolymers; polypropylene such as homopolypropylene, block copolymers of polypropylene (e.g., block copolymer of propylene and ethylene), and random copolymers of polypropylene (e.g., random copolymer of propylene and ethylene); propylene-α-olefin copolymers; and ethylene-butene-propylene terpolymers. Among these, polypropylene is preferred. When polyolefin resins are copolymers, they may be block copolymers or random copolymers. These polyolefin resins may be used individually or in combination of two or more.

[0095] Furthermore, the polyolefin may be a cyclic polyolefin. A cyclic polyolefin is a copolymer of an olefin and a cyclic monomer. Examples of olefins that are constituent monomers of the cyclic polyolefin include ethylene, propylene, 4-methyl-1-pentene, styrene, butadiene, isoprene, and the like. Examples of cyclic monomers that are constituent monomers of the cyclic polyolefin include cyclic alkenes such as norbornene; and cyclic dienes such as cyclopentadiene, dicyclopentadiene, cyclohexadiene, norbornadiene, and the like. Among these, cyclic alkenes are preferred, and norbornene is more preferred.

[0096] Acid-modified polyolefins are polymers obtained by modifying polyolefins through block polymerization or graft polymerization with an acid component. Examples of polyolefins that can be acid-modified include the aforementioned polyolefins, copolymers obtained by copolymerizing the aforementioned polyolefins with polar molecules such as acrylic acid or methacrylic acid, or polymers such as cross-linked polyolefins. Examples of acid components used for acid modification include carboxylic acids or their anhydrides, such as maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, and itaconic anhydride.

[0097] Acid-modified polyolefins may also be acid-modified cyclic polyolefins. Acid-modified cyclic polyolefins are polymers obtained by copolymerizing a portion of the monomers constituting a cyclic polyolefin with an acid component, or by block polymerization or graft polymerization of an acid component to a cyclic polyolefin. The cyclic polyolefin to be acid-modified is the same as described above. Furthermore, the acid component used for acid modification is the same as the acid component used for modifying the polyolefin described above.

[0098] Preferred acid-modified polyolefins include polyolefins modified with carboxylic acids or their anhydrides, polypropylenes modified with carboxylic acids or their anhydrides, maleic anhydride-modified polyolefins, and maleic anhydride-modified polypropylenes.

[0099] The heat-sealable resin layer 4 may be formed by a single resin or by a blended polymer of two or more resins. Furthermore, the heat-sealable resin layer 4 may be formed as a single layer or as two or more layers of the same or different resins.

[0100] Furthermore, the heat-fusible resin layer 4 may contain a lubricant or the like as needed. When the heat-fusible resin layer 4 contains a lubricant, the moldability of the exterior material for the energy storage device can be improved. The lubricant is not particularly limited, and known lubricants can be used. The lubricant may be used alone or in combination of two or more types.

[0101] The lubricant is not particularly limited, but amide-based lubricants are preferred. Specific examples of lubricants include those exemplified in base layer 1. The lubricant may be used alone or in combination of two or more types.

[0102] When a lubricant is present on the surface of the heat-fusible resin layer 4, the amount present is not particularly limited, but from the viewpoint of improving the moldability of the exterior material for energy storage devices, it is preferably 10 to 50 mg / m². 2 To a certain extent, more preferably 15-40 mg / m² 2 The degree can be described as follows.

[0103] The lubricant present on the surface of the heat-fusible resin layer 4 may be a lubricant contained in the resin constituting the heat-fusible resin layer 4 that has seeped out, or a lubricant may be applied to the surface of the heat-fusible resin layer 4.

[0104] Furthermore, the thickness of the heat-fusible resin layer 4 is not particularly limited as long as the heat-fusible resin layers heat-fuse together to seal the energy storage device elements, but for example, it can be about 100 μm or less, preferably about 85 μm or less, and more preferably about 15 to 85 μm. For example, if the thickness of the adhesive layer 5 described later is 10 μm or more, the thickness of the heat-fusible resin layer 4 can be preferably about 85 μm or less, and more preferably about 15 to 45 μm. For example, if the thickness of the adhesive layer 5 described later is less than 10 μm or if the adhesive layer 5 is not provided, the thickness of the heat-fusible resin layer 4 can be preferably about 20 μm or more, and more preferably about 35 to 85 μm.

[0105] [Adhesive layer 5] In the exterior material for energy storage devices of this disclosure, the adhesive layer 5 is a layer provided as necessary between the barrier layer 3 (or corrosion-resistant coating (such as an acid-resistant coating)) and the heat-fusible resin layer 4 in order to firmly bond them together.

[0106] The adhesive layer 5 is formed of a resin capable of bonding the barrier layer 3 and the heat-fusible resin layer 4. The resin used to form the adhesive layer 5 can be the same as the adhesive exemplified in the adhesive layer 2. Preferably, the resin used to form the adhesive layer 5 contains a polyolefin skeleton, such as the polyolefin and acid-modified polyolefin exemplified in the heat-fusible resin layer 4. The presence of a polyolefin skeleton in the resin constituting the adhesive layer 5 can be analyzed by methods such as infrared spectroscopy and gas chromatography-mass spectrometry, and the analytical method is not particularly limited. Furthermore, when the resin constituting the adhesive layer 5 is analyzed by infrared spectroscopy, it is preferable to detect a peak originating from maleic anhydride. For example, when maleic anhydride-modified polyolefin is measured by infrared spectroscopy, a peak originating from maleic anhydride is detected at wavenumber 1760 cm⁻¹. -1 Nearby wave frequency 1780cm -1 A peak originating from maleic anhydride is detected in the vicinity. However, if the degree of acid denaturation is low, the peak may become small and not be detected. In that case, analysis is possible by nuclear magnetic resonance spectroscopy.

[0107] From the viewpoint of firmly bonding the barrier layer 3 and the heat-fusible resin layer 4, the adhesive layer 5 preferably contains an acid-modified polyolefin. Particularly preferred as the acid-modified polyolefin are polyolefins modified with a carboxylic acid or its anhydride, polypropylenes modified with a carboxylic acid or its anhydride, maleic anhydride-modified polyolefins, and maleic anhydride-modified polypropylenes.

[0108] Furthermore, from the viewpoint of reducing the thickness of the exterior material for energy storage devices while providing excellent shape stability after molding, it is more preferable that the adhesive layer 5 is a cured product of a resin composition containing an acid-modified polyolefin and a curing agent. Examples of acid-modified polyolefins include those mentioned above.

[0109] Furthermore, the adhesive layer 5 is preferably a cured product of a resin composition comprising an acid-modified polyolefin and at least one selected from the group consisting of compounds having isocyanate groups, compounds having oxazoline groups, and compounds having epoxy groups, and is particularly preferably a cured product of a resin composition comprising an acid-modified polyolefin and at least one selected from the group consisting of compounds having isocyanate groups and compounds having epoxy groups. Furthermore, the adhesive layer 5 preferably contains at least one selected from the group consisting of polyurethane, polyester, and epoxy resin, and more preferably contains polyurethane and epoxy resin. As polyester, for example, amide ester resin is preferred. Amide ester resin is generally produced by the reaction of a carboxyl group and an oxazoline group. The adhesive layer 5 is more preferably a cured product of a resin composition comprising at least one of these resins and the acid-modified polyolefin. Furthermore, if unreacted compounds containing isocyanate groups, compounds containing oxazoline groups, or curing agents such as epoxy resin remain in the adhesive layer 5, the presence of these unreacted compounds can be confirmed by methods selected from, for example, infrared spectroscopy, Raman spectroscopy, or time-of-flight secondary ion mass spectrometry (TOF-SIMS).

[0110] Furthermore, from the viewpoint of further improving the adhesion between the barrier layer 3 and the adhesive layer 5, it is preferable that the adhesive layer 5 is a cured product of a resin composition containing a curing agent having at least one selected from the group consisting of oxygen atoms, heterocyclic rings, C=N bonds, and COC bonds. Examples of curing agents having heterocyclic rings include curing agents having oxazoline groups and curing agents having epoxy groups. Examples of curing agents having C=N bonds include curing agents having oxazoline groups and curing agents having isocyanate groups. Examples of curing agents having COC bonds include curing agents having oxazoline groups, curing agents having epoxy groups, and polyurethane. The fact that the adhesive layer 5 is a cured product of a resin composition containing these curing agents can be confirmed by methods such as gas chromatography-mass spectrometry (GCMS), infrared spectroscopy (IR), time-of-flight secondary ion mass spectrometry (TOF-SIMS), and X-ray photoelectron spectroscopy (XPS).

[0111] While there are no particular limitations on the compound having an isocyanate group, polyfunctional isocyanate compounds are preferred from the viewpoint of effectively improving the adhesion between the barrier layer 3 and the adhesive layer 5. The polyfunctional isocyanate compound is not particularly limited as long as it is a compound having two or more isocyanate groups. Specific examples of polyfunctional isocyanate curing agents include pentane diisocyanate (PDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), polymerized or nurated versions thereof, mixtures thereof, and copolymers with other polymers. Adducts, burettes, and isocyanurates are also examples.

[0112] The content of the compound having an isocyanate group in the adhesive layer 5 is preferably in the range of 0.1 to 50% by mass, and more preferably in the range of 0.5 to 40% by mass, of the resin composition constituting the adhesive layer 5. This effectively enhances the adhesion between the barrier layer 3 and the adhesive layer 5.

[0113] Compounds containing an oxazoline group are not particularly limited as long as they have an oxazoline skeleton. Specific examples of compounds containing an oxazoline group include those with a polystyrene main chain and those with an acrylic main chain. Commercially available examples include the Epocross series manufactured by Nippon Shokubai Co., Ltd.

[0114] The proportion of the compound having an oxazoline group in the adhesive layer 5 is preferably in the range of 0.1 to 50% by mass, and more preferably in the range of 0.5 to 40% by mass, of the resin composition constituting the adhesive layer 5. This effectively enhances the adhesion between the barrier layer 3 and the adhesive layer 5.

[0115] Examples of compounds having epoxy groups include epoxy resins. The epoxy resin is not particularly limited as long as it is capable of forming a crosslinked structure by the epoxy groups present in the molecule; known epoxy resins can be used. The weight-average molecular weight of the epoxy resin is preferably around 50 to 2000, more preferably around 100 to 1000, and even more preferably around 200 to 800. In this disclosure, the weight-average molecular weight of the epoxy resin is the value measured by gel permeation chromatography (GPC) under conditions using polystyrene as a standard sample.

[0116] Specific examples of epoxy resins include glycidyl ether derivatives of trimethylolpropane, bisphenol A diglycidyl ether, modified bisphenol A diglycidyl ether, novolac glycidyl ether, glycerin polyglycidyl ether, and polyglycerin polyglycidyl ether. Epoxy resins may be used individually or in combination of two or more types.

[0117] The proportion of epoxy resin in the adhesive layer 5 is preferably in the range of 0.1 to 50% by mass, and more preferably in the range of 0.5 to 40% by mass, of the resin composition constituting the adhesive layer 5. This effectively enhances the adhesion between the barrier layer 3 and the adhesive layer 5.

[0118] The polyurethane is not particularly limited, and any known polyurethane can be used. The adhesive layer 5 may be, for example, a cured product of a two-component polyurethane.

[0119] The proportion of polyurethane in the adhesive layer 5 is preferably in the range of 0.1 to 50% by mass, and more preferably in the range of 0.5 to 40% by mass, of the resin composition constituting the adhesive layer 5. This effectively enhances the adhesion between the barrier layer 3 and the adhesive layer 5 in an atmosphere where components that induce corrosion of the barrier layer, such as electrolytes, are present.

[0120] Furthermore, if the adhesive layer 5 is a cured product of a resin composition containing at least one compound selected from the group consisting of compounds having isocyanate groups, compounds having oxazoline groups, and epoxy resins, and the acid-modified polyolefin, the acid-modified polyolefin functions as the main agent, and the compounds having isocyanate groups, compounds having oxazoline groups, and compounds having epoxy groups each function as curing agents.

[0121] The thickness of the adhesive layer 5 is preferably about 50 μm or less, about 40 μm or less, about 30 μm or less, about 20 μm or less, or about 5 μm or less. Alternatively, the thickness of the adhesive layer 5 is preferably about 0.1 μm or more, or about 0.5 μm or more. The range of this thickness is preferably about 0.1 to 50 μm, about 0.1 to 40 μm, about 0.1 to 30 μm, about 0.1 to 20 μm, about 0.1 to 5 μm, about 0.5 to 50 μm, about 0.5 to 40 μm, about 0.5 to 30 μm, about 0.5 to 20 μm, or about 0.5 to 5 μm. More specifically, in the case of the adhesive exemplified in adhesive layer 2, or the cured product of acid-modified polyolefin and a curing agent, the thickness is preferably about 1 to 10 μm, more preferably about 1 to 5 μm. Furthermore, when using the resin exemplified in the heat-fusible resin layer 4, the thickness is preferably about 2 to 50 μm, more preferably about 10 to 40 μm. When the adhesive layer 5 is the adhesive exemplified in the adhesive layer 2, or a cured product of a resin composition containing an acid-modified polyolefin and a curing agent, the adhesive layer 5 can be formed, for example, by applying the resin composition and curing it by heating. Also, when using the resin exemplified in the heat-fusible resin layer 4, it can be formed, for example, by extrusion molding of the heat-fusible resin layer 4 and the adhesive layer 5.

[0122] [Surface coating layer 6] The exterior material for energy storage devices of this disclosure may optionally include a surface coating layer 6 on the base layer 1 (on the side opposite to the barrier layer 3 of the base layer 1) for the purpose of improving at least one of the following: aesthetics, electrolyte resistance, scratch resistance, and moldability. The surface coating layer 6 is the outermost layer of the exterior material for energy storage devices when the energy storage device is assembled using the exterior material for energy storage devices. As described above, in the exterior material for energy storage devices of this disclosure, the b * A value of -0.20 or less ensures excellent visibility of the identification mark printed on the surface under a light source in a yellow room. However, in some cases, the exterior material for the energy storage device may exhibit a slight bluish tint, resulting in visible color unevenness. However, if the outermost layer of the exterior material for the energy storage device of this disclosure is provided with a surface coating layer 6, the surface coating layer diffuses light and suppresses gloss, thus suppressing the occurrence of color unevenness and improving visual uniformity. On the other hand, if the outermost layer of the exterior material for the energy storage device of this disclosure is not provided with a surface coating layer 6, the surface of the exterior material for the energy storage device will have high gloss and scratches will be easily noticeable. However, if the surface coating layer 6 is provided, the surface coating layer diffuses light and suppresses gloss, resulting in scratches being less noticeable. These advantages are particularly pronounced when the surface coating layer 6 contains additives (especially matting agents) described later.

[0123] Furthermore, in the exterior material for energy storage devices of the present disclosure, the exterior material for energy storage devices is made to have a black appearance by coloring the surface coating layer 6 black, and then the above b * The value can be preferably set to -0.20 or less. However, if the surface coating layer 6 is colored black, as in the case where the adhesive layer 2 or the colored layer 21 described above is colored black, then the above b * The value will not be less than -0.20. By adjusting the composition of the surface coating layer 6, such as the type and amount of coloring agent contained in it, the composition of the base layer 1, the adhesive layer 2 and coloring layer 21 which are located outside the barrier layer 3, and the aging treatment conditions for the exterior material for the energy storage device described later, the appearance of the exterior material for the energy storage device can be made black, and the above b * The value can be set to -0.20 or less.* Value and a * The same applies to setting values.

[0124] The surface coating layer 6 can be formed from a resin such as polyvinylidene chloride, polyester, polyurethane, acrylic resin, or epoxy resin.

[0125] If the resin forming the surface coating layer 6 is a curable resin, it may be either a one-component curable resin or a two-component curable resin, but is preferably a two-component curable resin. Examples of two-component curable resins include two-component curable polyurethane, two-component curable polyester, and two-component curable epoxy resin. Among these, two-component curable polyurethane is preferred.

[0126] Examples of two-component curable polyurethanes include polyurethanes comprising a main component containing a polyol compound and a curing agent containing an isocyanate compound. Preferably, two-component curable polyurethanes are those in which a polyol such as polyester polyol, polyether polyol, and acrylic polyol is the main component and an aromatic or aliphatic polyisocyanate is the curing agent. Furthermore, it is preferable to use a polyester polyol as the polyol compound, which has hydroxyl groups not only at the terminals of the repeating units but also in the side chains. Examples of curing agents include aliphatic, alicyclic, aromatic, and aromaticaliphatic isocyanate compounds. Examples of isocyanate compounds include hexamethylene diisocyanate (HDI), xylylene diisocyanate (XDI), isophorone diisocyanate (IPDI), hydrogenated XDI (H6XDI), hydrogenated MDI (H12MDI), tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), and naphthalene diisocyanate (NDI). Furthermore, examples include polyfunctional isocyanate modified products derived from one or more of these diisocyanates. Polyisocyanate compounds can also be used as polymers (e.g., trimers). Examples of such polymers include adducts, biuretes, and nurates. The surface coating layer 6 being formed of polyurethane provides excellent electrolyte resistance to the exterior material for energy storage devices.

[0127] The surface coating layer 6 may contain, as necessary, additives such as the aforementioned lubricants, colorants, antiblocking agents, matting agents, flame retardants, antioxidants, tackifiers, and antistatic agents in at least one of its surface and interior, depending on the functionality to be provided to the surface coating layer 6 and its surface. Examples of additives include fine particles with an average particle size of about 0.5 nm to 5 μm. The average particle size of the additive is the median diameter measured by a laser diffraction / scattering particle size distribution analyzer.

[0128] The additive may be either inorganic or organic. Furthermore, there are no particular restrictions on the shape of the additive; examples include spherical, fibrous, plate-like, amorphous, or flaky forms.

[0129] Specific examples of additives include talc, silica, graphite, kaolin, montmorillonite, mica, hydrotalcite, silica gel, zeolite, aluminum hydroxide, magnesium hydroxide, zinc oxide, magnesium oxide, aluminum oxide, neodymium oxide, antimony oxide, titanium oxide, cerium oxide, calcium sulfate, barium sulfate, calcium carbonate, calcium silicate, lithium carbonate, calcium benzoate, calcium oxalate, magnesium stearate, alumina, carbon black, carbon nanotubes, high-melting-point nylon, acrylate resin, cross-linked acrylic, cross-linked styrene, cross-linked polyethylene, benzoguanamine, gold, aluminum, copper, nickel, and the like. Additives may be used individually or in combination of two or more. Among these additives, calcium carbonate is preferred from the viewpoint of improving distinguishability. Because calcium carbonate has a bluish tint, using it as an additive in the surface coating layer makes it preferable to use the aforementioned b * The value can be suitably set to -0.20 or less. Furthermore, it is preferable to use a mixture of silica and calcium carbonate as additives. By using silica as an additive to the surface coating layer, reflected light is more easily diffused, making it possible to give the exterior material for energy storage devices a more bluish appearance, as described in b * The value can be suitably set to -0.20 or less. Among these additives, silica, barium sulfate, and titanium oxide are preferred from the viewpoint of dispersion stability and cost. In addition, the additives may be subjected to various surface treatments such as insulating treatment and high dispersibility treatment.

[0130] If the surface coating layer 6 contains a coloring agent, known coloring agents such as pigments and dyes can be used. Furthermore, only one type of coloring agent may be used, or two or more types may be mixed. Specific examples of coloring agents included in the surface coating layer 6 are the same as those exemplified in the [Adhesive Layer 2] section. The preferred content of coloring agents in the surface coating layer 6 is also the same as that described in the [Adhesive Layer 2] section.

[0131] For example, when a blackening agent is incorporated into the surface coating layer 6, the content of the blackening agent in the surface coating layer 6 is not particularly limited as long as the exterior material for the energy storage device is colored black, and is, for example, about 5 to 60% by mass, preferably 10 to 40% by mass. Also, when a bluening agent is incorporated into the surface coating layer 6, the content of the bluening agent in the surface coating layer 6 is not particularly limited as long as the exterior material for the energy storage device is colored black, and is, for example, about 0.5 to 30% by mass, preferably 1 to 20% by mass.

[0132] Furthermore, for example, when a black agent and a blue agent are blended in the surface coating layer 6, the ratio of the black agent to the blue agent in the surface coating layer 6 is such that the black agent is 100 parts by mass, and the proportion of the blue agent is preferably about 0.1 parts by mass or more, more preferably about 1 part by mass or more, and even more preferably about 10 parts by mass or more. The proportion of the blue agent is preferably about 150 parts by mass or less, and more preferably about 100 parts by mass or less. The preferred range for the blue agent is about 0.1 to 150 parts by mass, about 0.1 to 100 parts by mass, about 1 to 150 parts by mass, about 1 to 100 parts by mass, about 10 to 150 parts by mass, and about 10 to 100 parts by mass.

[0133] The method for forming the surface coating layer 6 is not particularly limited, and for example, a method of applying a resin to form the surface coating layer 6 can be used. If an additive is to be incorporated into the surface coating layer 6, the resin mixed with the additive can be applied.

[0134] The thickness of the surface coating layer 6 is not particularly limited as long as it performs the above-mentioned functions as a surface coating layer 6, and for example, it can be about 0.5 to 10 μm, preferably about 1 to 5 μm.

[0135] For example, if the adhesive layer is a black-colored layer, it is preferable that the surface coating layer located outside the adhesive layer be transparent or translucent.

[0136] 3. Method for manufacturing exterior materials for energy storage devices The method for manufacturing an exterior material for an energy storage device is not particularly limited, as long as a laminate is obtained by laminating each layer of the exterior material for an energy storage device of the disclosed herein, and includes a step of laminating at least a base layer 1, a barrier layer 3, and a heat-fusible resin layer 4 in that order. Specifically, the method for manufacturing an exterior material for an energy storage device of the disclosed herein is a method for manufacturing an exterior material for an energy storage device that has a black appearance, and includes a step of obtaining a laminate in which at least a base layer, a barrier layer, and a heat-fusible resin layer are laminated in that order from the outside, and the reflected light L measured from the outside of the laminate under the measurement conditions of SCI method, field of view 10° and light source F2 * a * b * b in color space * The value is -0.20 or less.

[0137] An example of a method for manufacturing the exterior material for energy storage devices of this disclosure is as follows. First, a laminate (hereinafter sometimes referred to as "laminated laminate A") is formed by sequentially laminating a base layer 1, an adhesive layer 2, and a barrier layer 3. Specifically, laminate A can be formed by a dry lamination method in which the adhesive used to form the adhesive layer 2 is applied to the base layer 1 or, if necessary, to the barrier layer 3 whose surface has been chemically treated, using a coating method such as gravure coating or roll coating, and after drying, the barrier layer 3 or base layer 1 is laminated and the adhesive layer 2 is cured.

[0138] Next, a heat-fusible resin layer 4 is laminated onto the barrier layer 3 of laminate A. When the heat-fusible resin layer 4 is directly laminated onto the barrier layer 3, the heat-fusible resin layer 4 can be laminated onto the barrier layer 3 of laminate A by methods such as thermal lamination or extrusion lamination. When an adhesive layer 5 is provided between the barrier layer 3 and the heat-fusible resin layer 4, for example, (1) a method of laminating the adhesive layer 5 and the heat-fusible resin layer 4 by extrusion onto the barrier layer 3 of laminate A (co-extrusion lamination method, tandem lamination method), (2) a method of forming a laminate in which the adhesive layer 5 and the heat-fusible resin layer 4 are laminated separately, and then laminating this onto the barrier layer 3 of laminate A by thermal lamination, or a method of forming a laminate in which the adhesive layer 5 is laminated onto the barrier layer 3 of laminate A, and then laminating this with the heat-fusible resin layer 4 by thermal lamination. (3) A method of lamination by pouring a molten adhesive layer 5 between the barrier layer 3 of the laminate A and the heat-fusible resin layer 4 which has been previously formed into a sheet, thereby bonding the laminate A and the heat-fusible resin layer 4 via the adhesive layer 5 (sandwich lamination method); (4) A method of lamination by applying an adhesive solution to the barrier layer 3 of the laminate A to form the adhesive layer 5, drying it, or even baking it, and then laminating the heat-fusible resin layer 4 which has been previously formed into a sheet, onto this adhesive layer 5.

[0139] When a surface coating layer 6 is provided, the surface coating layer 6 is laminated on the surface of the base layer 1 opposite to the barrier layer 3. The surface coating layer 6 can be formed, for example, by applying the resin used to form the surface coating layer 6 to the surface of the base layer 1. The order of the steps of laminating the barrier layer 3 to the surface of the base layer 1 and laminating the surface coating layer 6 to the surface of the base layer 1 is not particularly limited. For example, the surface coating layer 6 may be formed on the surface of the base layer 1, and then the barrier layer 3 may be formed on the surface of the base layer 1 opposite to the surface coating layer 6.

[0140] As described above, a laminate is formed comprising, in order from the outside in, a surface coating layer 6 (provided as necessary), a base layer 1, an adhesive layer 2 (provided as necessary), a barrier layer 3, an adhesive layer 5 (provided as necessary), and a heat-fusible resin layer 4. In order to strengthen the adhesion of the adhesive layer 2 and adhesive layer 5 (provided as necessary), the laminate may be subjected to further heat treatment.

[0141] In exterior materials for energy storage devices, the processability of each layer constituting the laminate may be improved by subjecting it to surface activation treatments such as corona treatment, blast treatment, oxidation treatment, or ozone treatment, as needed. For example, by applying corona treatment to the surface of the substrate layer 1 opposite to the barrier layer 3, the printability of ink on the surface of the substrate layer 1 can be improved.

[0142] It is preferable to subject the exterior material for energy storage devices to an aging treatment after laminating each layer. By changing the aging treatment conditions of the exterior material for energy storage devices, the appearance of the exterior material for energy storage devices, which is black, can be changed. * value, a * value, and b * The value can be changed. Therefore, L * value, a * value, and b * It is preferable to select aging conditions with the aim of adjusting the value. Adjustment items for aging conditions include, for example, the heating rate, heating temperature, heating time, and whether or not pretreatment is performed and its temperature. Note that L can be adjusted depending on the aging conditions. * value, a * value, and b * The main factor causing the value to change is that the degree of aggregation of the colorants contained in the exterior material for energy storage devices changes depending on the aging treatment conditions.

[0143] 4. Applications of exterior materials for energy storage devices The exterior material for energy storage devices of this disclosure is used in packaging for sealing and housing energy storage device elements such as a positive electrode, a negative electrode, and an electrolyte. That is, an energy storage device can be formed by housing energy storage device elements, which include at least a positive electrode, a negative electrode, and an electrolyte, in packaging formed from the exterior material for energy storage devices of this disclosure.

[0144] Specifically, an energy storage device is provided by covering an energy storage device element, which comprises at least a positive electrode, a negative electrode, and an electrolyte, with the energy storage device exterior material of this disclosure, such that a flange portion (an area where heat-sealable resin layers come into contact) is formed around the periphery of the energy storage device element, with the metal terminals connected to the positive electrode and negative electrode respectively protruding outward, and then heat-sealing the heat-sealable resin layers of the flange portion to seal it. When housing the energy storage device element in a package formed from the energy storage device exterior material of this disclosure, the package is formed such that the heat-sealable resin portion of the energy storage device exterior material of this disclosure faces inward (the surface in contact with the energy storage device element).

[0145] The casing material for energy storage devices disclosed herein can be suitably used in energy storage devices such as batteries (including capacitors, capacitors, etc.). Furthermore, the casing material for energy storage devices disclosed herein can be used in either primary batteries or secondary batteries, but is preferably used in secondary batteries. The type of secondary battery to which the casing material for energy storage devices disclosed herein can be applied is not particularly limited, and examples include lithium-ion batteries, lithium-ion polymer batteries, all-solid-state batteries, lead-acid batteries, nickel-metal hydride batteries, nickel-cadmium batteries, nickel-iron batteries, nickel-zinc batteries, silver oxide-zinc batteries, metal-air batteries, polyvalent cation batteries, capacitors, capacitors, etc. Among these secondary batteries, lithium-ion batteries and lithium-ion polymer batteries are particularly suitable applications for the casing material for energy storage devices disclosed herein. [Examples]

[0146] The present disclosure will be described in detail below with reference to examples and comparative examples. However, the present disclosure is not limited to the examples.

[0147] <Manufacturing of exterior materials for energy storage devices> Examples 1-7, 14, 15 and Comparative Example 1 A stretched nylon (ONy) film (15 μm thick) was prepared as the base layer. Aluminum foil (JIS H4160:1994 A8021H-O (35 μm thick)) was prepared as the barrier layer. Next, the barrier layer and the base layer were laminated using a dry lamination method with the adhesive described later (a two-component urethane adhesive containing a coloring agent), and then an aging treatment was performed to create a laminate of the base layer / adhesive layer / barrier layer. Both sides of the aluminum foil were treated with a chemical conversion treatment. The chemical conversion treatment of the aluminum foil involved a treatment solution consisting of phenolic resin, chromium fluoride compound, and phosphoric acid, with a chromium coating amount of 10 mg / m². 2 (Dry The coating was applied to both sides of the aluminum foil using a roll-coating method and then baked to achieve the desired dry mass.

[0148] Next, maleic anhydride-modified polypropylene as an adhesive layer (20 μm thick) and random polypropylene as a heat-fusible resin layer (20 μm thick) were co-extruded onto the barrier layer of each laminate obtained above, thereby laminating the adhesive layer / heat-fusible resin layer on top of the barrier layer. Furthermore, a resin composition containing silica particles (the resin is a polyurethane resin formed from a mixture of a polyol compound and an isocyanate compound) was coated to a thickness of 3 μm onto the surface of the base layer of the obtained laminate to form a matte surface coating layer, and a laminate (total thickness 96 μm) was obtained in which the surface coating layer (3 μm) / base layer (15 μm thick) / adhesive layer (3 μm) / barrier layer (35 μm) / adhesive layer (20 μm) / heat-fusible resin layer (20 μm) were laminated in that order from the outside.

[0149] Example 8 In Example 1, a laminate (total thickness 93 μm) was obtained by laminating a base layer (thickness 15 μm) / adhesive layer (3 μm) / barrier layer (35 μm) / adhesive layer (20 μm) / heat-fusible resin layer (20 μm) in the same manner as in Example 1, except that a surface coating layer was not formed.

[0150] Example 9 In Example 3, a laminate (total thickness 93 μm) was obtained by laminating a base layer (thickness 15 μm) / adhesive layer (3 μm) / barrier layer (35 μm) / adhesive layer (20 μm) / heat-fusible resin layer (20 μm) in the same manner as in Example 3, except that a surface coating layer was not formed.

[0151] Example 10 In Example 4, a laminate (total thickness 93 μm) was obtained by laminating a base layer (thickness 15 μm) / adhesive layer (3 μm) / barrier layer (35 μm) / adhesive layer (20 μm) / heat-fusible resin layer (20 μm), in the same manner as in Example 4, except that a surface coating layer was not formed.

[0152] Example 11 In Example 5, a laminate (total thickness 93 μm) was obtained by laminating a base layer (thickness 15 μm) / adhesive layer (3 μm) / barrier layer (35 μm) / adhesive layer (20 μm) / heat-fusible resin layer (20 μm), in the same manner as in Example 5, except that a surface coating layer was not formed.

[0153] Example 12 In Example 2, a laminate (total thickness 93 μm) was obtained by laminating a base layer (thickness 15 μm) / adhesive layer (3 μm) / barrier layer (35 μm) / adhesive layer (20 μm) / heat-fusible resin layer (20 μm) in the same manner as in Example 2, except that a surface coating layer was not formed.

[0154] Examples 13, 16-20 In Example 1, a laminate (total thickness 93 μm) was obtained by laminating a base layer (thickness 15 μm) / adhesive layer (3 μm) / barrier layer (35 μm) / adhesive layer (20 μm) / heat-fusible resin layer (20 μm), except that no surface coating layer was formed and adhesives B, C4 to C8 listed in Table 1 were used instead of adhesive A for forming the adhesive layer, in the same manner as in Example 1.

[0155] <Adhesive> The following adhesives were used to form the adhesive layer between the substrate layer and the barrier layer. Table 1 shows the types of adhesives used in each example and comparative example. [Adhesive A] A two-component urethane adhesive (a mixture of a polyol compound and an aromatic isocyanate compound) containing carbon black (secondary particle size 0.2 μm) as a blackening agent. [Adhesive B] As a blackening agent, the two-component urethane adhesive (a mixture of a polyol compound and an aromatic isocyanate compound) contains carbon black with a primary particle size larger than the carbon black contained in adhesive A (secondary particle size 0.2 μm). [Adhesive C1] As a blackening agent, the same carbon black contained in adhesive A was used. A two-component urethane adhesive (a mixture of a polyol compound and an aromatic isocyanate compound) containing 26 parts by mass of carbon black and 4 parts by mass of copper phthalocyanine as a bluening agent. [Adhesive C2] As a blackening agent, the same carbon black contained in adhesive A was used. A two-component urethane adhesive (a mixture of a polyol compound and an aromatic isocyanate compound) was formulated, containing 15 parts by mass of copper phthalocyanine as a bluening agent per 15 parts by mass of carbon black. [Adhesive C3] As a blackening agent, the same carbon black contained in adhesive A was used. A two-component urethane adhesive (a mixture of a polyol compound and an aromatic isocyanate compound) containing 13 parts by mass of carbon black and 17 parts by mass of copper phthalocyanine as a bluening agent. [Adhesive C4] As a blackening agent, the same carbon black contained in adhesive A was used. A two-component urethane adhesive (a mixture of a polyol compound and an aromatic isocyanate compound) was formulated, containing 20 parts by mass of carbon black and 10 parts by mass of copper phthalocyanine as a bluening agent. [Adhesive C5] As a blackening agent, the same carbon black contained in adhesive A was used. A two-component urethane adhesive (a mixture of a polyol compound and an aromatic isocyanate compound) containing 18 parts by mass of carbon black and 12 parts by mass of copper phthalocyanine as a bluening agent. [Adhesive C6] As a blackening agent, the same carbon black contained in adhesive A was used. A two-component urethane adhesive (a mixture of a polyol compound and an aromatic isocyanate compound) containing 8 parts by mass of copper phthalocyanine as a bluening agent per 22 parts by mass of carbon black. [Adhesive C7] As a blackening agent, the same carbon black contained in adhesive A was used. A two-component urethane adhesive (a mixture of a polyol compound and an aromatic isocyanate compound) containing 16 parts by mass of carbon black and 14 parts by mass of copper phthalocyanine as a bluening agent. [Adhesive C8] As a blackening agent, the same carbon black contained in adhesive A was used. A two-component urethane adhesive (a mixture of a polyol compound and an aromatic isocyanate compound) containing 14 parts by mass of carbon black and 16 parts by mass of copper phthalocyanine as a bluening agent.

[0156] <Aging process conditions> The aging treatment conditions used to adjust the color of the exterior material for energy storage devices manufactured in each example and comparative example are as follows. [Condition A] Leave undisturbed for 12 hours in an 80°C environment. [Condition B] First, as Step 1, leave it standing at room temperature (around 25°C) for 3 hours. Next, as Step 2, leave it standing in a 55°C environment for 3 hours. Finally, as Step 3, leave it standing in an 80°C environment for 12 hours. [Condition C] Leave it undisturbed for 3 days in an environment of 60°C to 100°C.

[0157] <L * value, a * Value and b * Measurement of values ​​> For the exterior materials for energy storage devices obtained in each example and comparative example, the observation conditions of a Konica Minolta spectrophotometer (CM-700d), calibrated with a white calibration cap (CM-A177: manufactured by Konica Minolta), were set to 10°, the observation light source to F2, and CSI mode (JIS Z8722-2009), and the L of the outer (substrate layer side) surface was measured. * a * , b * Measurements were performed under normal temperature and humidity conditions. Three measurements were taken for each sample, and the average value is shown in Table 1 as the evaluation result.

[0158] <Measurement of Cu element by X-ray fluorescence analysis (XRF)> The presence or absence of Cu element detection was confirmed by X-ray fluorescence analysis (XRF) under the following measurement conditions for the exterior materials for energy storage devices obtained in Examples 1-5 and Comparative Example 1. As a result, no peaks originating from Cu element were detected in Examples 1, 2 and Comparative Example 1. However, peaks originating from Cu element were detected in Examples 3, 4, and 5. The peak intensity of CuKα was 0.4 for Example 3, 1.2 for Example 4, and 1.2 for Example 5. (Measurement conditions) Equipment used: EDX-800HS (manufactured by Shimadzu Corporation) X-ray: Rh target Voltage: 50kV Current: 1000μA Irradiation area: 100φ Measurement time: 100 seconds Measurement atmosphere: Vacuum Measurement surface: Outer side (X-rays are irradiated onto the outer surface of the casing material for the energy storage device) Analysis Method: Automatic intensity calculation will be performed using the "PCEDX" software included with the EDX-800HS (manufactured by Shimadzu Corporation). Specifically, peak detection will be performed on the spectrum obtained from the measurement. The coefficient for the peak detection condition will be set to 10. Next, the detected intensity will be calculated from the intensity calculation for the detected peaks.

[0159] <Identifiability within the Yellow Room> Samples were prepared by printing the number sequence "0123456789" with a dot diameter of approximately 0.3 mm and a string height of approximately 1.5 mm onto the surface of the surface coating layer of the exterior material for energy storage devices obtained in each example and comparative example, using an inkjet printer (Markem Image Co., Ltd., model 9040). White ink was used for printing. Next, each sample was observed with the naked eye from a distance of 30 cm in a yellow room, and its identifiability was evaluated according to the following evaluation criteria. The results are shown in Table 1. (Evaluation Criteria) A: It can be recognized immediately. B: It takes a few seconds to recognize. C: Can be recognized by changing the sample angle.

[0160] <Black exterior> In a room under fluorescent lighting, each sample prepared in the aforementioned <Distinguishing properties in the yellow room> was observed with the naked eye and evaluated to determine whether its appearance was perceived as black, according to the following evaluation criteria. The results are shown in Table 1. (Evaluation Criteria) A: It is clearly perceived as black. B: Blue or red is slightly recognizable, but black is recognized without any problems. C: There is a risk that blue or red will be clearly recognized, but black will not be recognized.

[0161] [Table 1]

[0162] As is clear from the results shown in Table 1, the exterior materials for energy storage devices of Examples 1 to 20 measured the reflected light L from the outside under the measurement conditions of SCI method, field of view 10°, and light source F2. * a * b * b in color space * Since the value is -0.20 or less, it can be seen that, despite being an exterior material for energy storage devices with a black appearance, the identification mark printed on the surface is highly visible in the yellow room. Furthermore, the exterior materials for energy storage devices in Examples 1 to 20 exhibited excellent visibility of the identification mark printed on the surface not only in the yellow room but also in a room under typical fluorescent lighting. In addition, the exterior materials for energy storage devices in Examples 1 to 20 could be recognized without any problems as being black in a room under typical fluorescent lighting.

[0163] As described above, this disclosure provides inventions in the following embodiments. Item 1. An exterior material for an energy storage device having a black appearance, The exterior material for the energy storage device is composed of a laminate comprising, in order from the outside, at least a base layer, a barrier layer, and a heat-sealable resin layer. The L of the reflected light was measured from the outside of the laminate under the measurement conditions of SCI method, field of view 10°, and light source F2. * a * b * b in color space * Exterior material for energy storage devices, with a value of -0.20 or less. Item 2. The L of the reflected light measured from the outside of the laminate under the measurement conditions of SCI method, field of view 10°, and light source F2. * a * b * a in color space * An exterior material for an energy storage device as described in item 1, wherein the value is +0.2 or less. Item 3. An adhesive layer is provided between the base material layer and the barrier layer. The exterior material for an energy storage device according to item 1 or 2, wherein the adhesive layer contains a coloring agent. Item 4. A colored layer is provided between the substrate layer and the barrier layer. The exterior material for an energy storage device according to any one of claims 1 to 3, wherein the colored layer contains a pigment. Item 5. An exterior material for an energy storage device according to any one of items 1 to 4, wherein the base material layer is provided with a surface coating layer on the side opposite to the barrier layer. Item 6. An outer casing material for an energy storage device according to any one of items 1 to 5, wherein Cu elements are detected when the laminate is analyzed from the outside by X-ray fluorescence analysis. Item 7. A method for manufacturing an exterior material for an energy storage device that has a black appearance, The process includes obtaining a laminate in which, in order from the outside in, at least a base layer, a barrier layer, and a heat-fusible resin layer are laminated. The L of the reflected light was measured from the outside of the laminate under the measurement conditions of SCI method, field of view 10°, and light source F2. * a * b * b in color space * A method for manufacturing an exterior material for an energy storage device, wherein the value is -0.20 or less. Item 8. An energy storage device in which an energy storage device element comprising at least a positive electrode, a negative electrode, and an electrolyte is housed in a package formed from an outer casing material for energy storage devices as described in any one of items 1 to 6. [Explanation of Symbols]

[0164] 1 Base material layer 2 Adhesive layer 21 Colored layer 3. Barrier layer 4 Heat-fusible resin layer 5 Adhesive layer 6 Surface coating layer 10. Exterior materials for energy storage devices

Claims

1. An exterior material for an energy storage device that has a black appearance, The exterior material for the energy storage device is composed of a laminate comprising, in order from the outside, at least a surface coating layer, a base layer, a barrier layer, and a heat-sealable resin layer. The L of the reflected light was measured from the outside of the laminate under the measurement conditions of SCI method, field of view 10°, and light source F2. * a * b * b in color space * The value is between -5.00 and -0.

20. The reflected light L * a * b * a in color space * The value is between -3.50 and +0.

20. The L of the reflected light * a * b * The L in the color space * value is 40 or less, an exterior material for a power storage device.

2. The exterior material for an energy storage device according to claim 1, wherein the surface coating layer contains titanium oxide.

3. The exterior material for an energy storage device according to claim 1, wherein the surface coating layer contains silica.

4. The exterior material for an energy storage device according to claim 1, wherein the surface coating layer contains kaolin.

5. An adhesive layer is provided between the substrate layer and the barrier layer. The exterior material for an energy storage device according to any one of claims 1 to 4, wherein the adhesive layer contains a coloring agent.

6. A colored layer is provided between the substrate layer and the barrier layer. The exterior material for an energy storage device according to any one of claims 1 to 4, wherein the colored layer contains a pigment.

7. An exterior material for an energy storage device according to any one of claims 1 to 6, comprising an adhesive layer between the barrier layer and the heat-fusible resin layer.

8. The exterior material for an energy storage device according to claim 7, wherein the thickness of the adhesive layer is 5 μm or less.

9. The exterior material for an energy storage device according to claim 7 or 8, wherein the thickness of the adhesive layer is 0.1 μm or more.

10. The exterior material for an energy storage device according to any one of claims 1 to 9, wherein the barrier layer includes a metal foil and a resin layer.

11. A method for manufacturing an exterior material for an energy storage device that has a black appearance, The process includes obtaining an exterior material for an energy storage device, which consists of a laminate comprising, in order from the outside in, at least a surface coating layer, a base material layer, a barrier layer, and a heat-fusible resin layer, The L of the reflected light was measured from the outside of the laminate under the measurement conditions of SCI method, field of view 10°, and light source F2. * a * b * b in color space * The value is between -5.00 and -0.

20. The reflected light L * a * b * a in color space * The value is between -3.50 and +0.

20. The reflected light L * a * b * L in color space * A method for manufacturing an exterior material for an energy storage device, wherein the value is 40 or less.

12. The method for manufacturing an exterior material for an energy storage device according to claim 11, further comprising an adhesive layer between the barrier layer and the heat-fusible resin layer.

13. A method for manufacturing an exterior material for an energy storage device according to claim 12, wherein the adhesive layer and the heat-fusible resin layer are laminated by a co-extrusion lamination method.

14. A method for manufacturing an exterior material for an energy storage device according to claim 12, wherein the adhesive layer and the heat-fusible resin layer are laminated by a thermal lamination method.

15. A method for manufacturing an exterior material for an energy storage device according to claim 12, wherein the adhesive layer and the heat-fusible resin layer are laminated by a sandwich lamination method.

16. An energy storage device in which an energy storage device element comprising at least a positive electrode, a negative electrode, and an electrolyte is housed in a package formed from an outer material for an energy storage device according to any one of claims 1 to 10.

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