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

Abstract

Provided is an outer packaging for electrical storage devices that is composed of a laminate provided with at least a substrate layer, a barrier layer, and a thermally adhesive resin layer in this order, wherein in heat seal strength measurement, in which measurement is performed upon heat-sealing together the thermally adhesive resin layer under conditions of a temperature of 190°C and a specific pressure of 1.0 MPa for 3 seconds and then separating the thermally adhesive resin layer, the heat seal strength decrease temperature T°C of the outer packaging for electrical storage devices is within the measured temperature of range of 110°C to 120°C. Heat seal strength decrease temperature T°C: the measured temperature in the heat seal strength measurement at which the heat seal strength reaches 35 N / 15 mm or higher, and at which the heat seal strength at the heat seal strength decrease temperature T°C +10°C is 10 N / 15 mm or lower.

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, conventionally, a film-like laminate in which a base layer / barrier layer / adhesive layer / heat-fusible resin layer is 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. 2002-8616 [Overview of the project] [Problems that the invention aims to solve]

[0007] In recent years, with the increasing speed and capacity of smartphone data communication, the amount of electricity consumed has also increased, leading to consideration of increasing the capacity of energy storage devices. However, increasing the capacity of batteries involves increasing the size of the container and the amount of reactive materials, which increases the amount of gas generated when the energy storage device experiences thermal runaway (i.e., when the energy storage device becomes hot), and increases the risk of explosion due to the rise in internal pressure of the energy storage device. In energy storage devices using metal casings (for example, metal can batteries), safety is ensured when gas is generated by installing a safety valve (see Patent Document 2).

[0008] However, with energy storage devices using laminated film-like exterior materials, it is difficult to install such safety valves, and preventing the expansion of the energy storage device due to gas generated inside the device at high temperatures remains a challenge.

[0009] On the other hand, during the baking process in the manufacturing of energy storage devices, the devices are exposed to high temperatures (for example, around 100°C). However, it is necessary to prevent the heat and gases generated during this baking process from causing the outer packaging material of the energy storage device to open.

[0010] Under these circumstances, the main objective of this disclosure is to provide an exterior material for an energy storage device, comprising a laminate comprising at least a base layer, a barrier layer, and a heat-fusible resin layer in that order, wherein the exterior material seals the energy storage device until the energy storage device reaches a high temperature (e.g., about 100°C), and when the energy storage device reaches a high temperature (e.g., about 110°C to 130°C) and the internal pressure rises excessively, the exterior material opens to release gas generated inside the energy storage device to the outside. [Means for solving the problem]

[0011] The inventors of the present disclosure have conducted intensive studies to solve the above problems. As a result, at least a power storage device exterior material composed of a laminate including a base material layer, a barrier layer, and a heat-sealable resin layer in this order, wherein the power storage device exterior material heat-seals the heat-sealable resin layers with each other under the conditions of a temperature of 190°C, a surface pressure of 1.0 MPa, and for 3 seconds, and in the heat-seal strength measurement measured by peeling the heat-sealable resin layers from each other, within the range of a measurement temperature of 110°C or higher and 120°C or lower, a heat-seal strength decrease temperature T°C is included, so that until the power storage device reaches a high temperature (for example, about 100°C), it is sealed by the power storage device exterior material, and when the power storage device reaches a high temperature (for example, about 110°C to 130°C) and the internal pressure rises excessively, the power storage device can be opened to release the gas generated inside the power storage device to the outside.

[0012] (Heat-seal strength decrease temperature T°C) In the heat-seal strength measurement, it is the measurement temperature at which the heat-seal strength becomes 35 N / 15 mm or more, and the heat-seal strength at the heat-seal strength decrease temperature T°C + 10°C is 10 N / 15 mm or less.

[0013] Based on these findings, the present disclosure has been completed through further studies. That is, the present disclosure provides an invention in the following aspects. At least a power storage device exterior material composed of a laminate including a base material layer, a barrier layer, and a heat-sealable resin layer in this order, wherein the power storage device exterior material heat-seals the heat-sealable resin layers with each other under the conditions of a temperature of 190°C, a surface pressure of 1.0 MPa, and for 3 seconds, and in the heat-seal strength measurement measured by peeling the heat-sealable resin layers from each other, within the range of a measurement temperature of 110°C or higher and 120°C or lower, a heat-seal strength decrease temperature T°C is included, the power storage device exterior material. (Heat-seal strength decrease temperature T°C) In the heat seal strength measurement, it is the measurement temperature at which the heat seal strength is 35 N / 15 mm or more, and the heat seal strength at the measurement temperature of the heat seal strength decrease temperature T °C + 10 °C is 10 N / 15 mm or less.

Advantages of the Invention

[0014] According to the present disclosure, there is provided an exterior material for a power storage device composed of a laminate including at least a base material layer, a barrier layer, and a heat-sealable resin layer in this order. Until the power storage device reaches a high temperature (for example, about 100 °C), it is sealed by the exterior material for the power storage device. When the power storage device reaches a high temperature (for example, about 110 °C to 130 °C) and the internal pressure rises excessively, the exterior material for the power storage device can be opened to release the gas generated inside the power storage device to the outside. Further, according to the present disclosure, a method for manufacturing an exterior material for a power storage device and a power storage device can also be provided.

Brief Description of the Drawings

[0015] [Figure 1] It is a schematic diagram showing an example of a cross-sectional structure of the exterior material for a power storage device of the present disclosure. [Figure 2] It is a schematic diagram showing an example of a cross-sectional structure of the exterior material for a power storage device of the present disclosure. [Figure 3] It is a schematic diagram showing an example of a cross-sectional structure of the exterior material for a power storage device of the present disclosure. [Figure 4] It is a schematic diagram for explaining a method of accommodating a power storage device element in a package formed by the exterior material for a power storage device of the present disclosure. [Figure 5] It is a schematic diagram for explaining a method of measuring heat seal strength. [Figure 6] It is a schematic diagram for explaining a method of measuring heat seal strength. [Figure 7] It is a schematic diagram for explaining a method of measuring softening point. [Figure 8] It is a schematic diagram of a differential molecular weight distribution curve.

Embodiments for Carrying Out the Invention

[0016] The exterior material for energy storage devices of the present disclosure is an exterior material for energy storage devices comprising a laminate comprising, in this order, a base layer, a barrier layer, and a heat-fusible resin layer, wherein the exterior material for energy storage devices is characterized in that, in a heat seal strength measurement performed by heat sealing the heat-fusible resin layers together under the conditions of a temperature of 190°C, a surface pressure of 1.0 MPa, and 3 seconds, and then peeling the heat-fusible resin layers together, the measured temperature range of 110°C to 120°C includes the following heat seal strength reduction temperature T°C. With this configuration, the exterior material for energy storage devices of the present disclosure is sealed by the exterior material until the energy storage device reaches a high temperature (for example, around 100°C), and when the energy storage device reaches a high temperature (for example, around 110°C to 130°C) and the internal pressure rises excessively, the energy storage device can be opened to release gas generated inside the energy storage device to the outside.

[0017] (Heat seal strength reduction temperature T℃) The heat seal strength reduction temperature T℃ is the measurement temperature at which the heat seal strength becomes 35 N / 15 mm or more in the heat seal strength measurement, and at the heat seal strength at the heat seal strength reduction temperature T℃ + 10℃ at which the heat seal strength becomes 10 N / 15 mm or less.

[0018] The exterior material for energy storage devices described herein will be described in detail below. In this disclosure, numerical ranges indicated by "~" mean "greater than or equal to" and "less than or equal to". For example, the notation 2~15mm means 2mm or more and 15mm or less.

[0019] Furthermore, in the case of exterior materials for energy storage devices, the Machine Direction (MD) and Transverse Direction (TD) of the barrier layer 3 described later can usually be determined during the manufacturing process. For example, when the barrier layer 3 is composed of metal foil such as aluminum alloy foil or stainless steel foil, linear lines called rolling marks are formed on the surface of the metal foil in the rolling direction (RD) of the metal foil. Since the rolling marks extend along the rolling direction, the rolling direction of the metal foil can be determined by observing the surface of the metal foil. Also, in the manufacturing process of a laminate, the MD of the laminate and the RD of the metal foil usually coincide, so the MD of the laminate can be determined by observing the surface of the metal foil in the laminate and identifying the rolling direction (RD) of the metal foil. In addition, since the TD of the laminate is perpendicular to the MD of the laminate, the TD of the laminate can also be determined.

[0020] Furthermore, if the MD of the exterior material for energy storage devices cannot be identified by the rolling marks of metal foils such as aluminum alloy foil or stainless steel foil, it can be identified by the following method. One method for confirming the MD of the exterior material for energy storage devices is to observe the cross-section of the heat-fusible resin layer of the exterior material with an electron microscope and confirm the sea-island structure. In this method, the direction parallel to the cross-section where the average diameter of the island shapes perpendicular to the thickness direction of the heat-fusible resin layer is maximum can be determined as the MD. Specifically, the sea-island structure is confirmed by observing electron microscope images of each of the cross-sections in the longitudinal direction of the heat-fusible resin layer and each of the cross-sections (a total of 10 cross-sections) from the direction parallel to the longitudinal cross-section, changing the angle by 10 degrees at a time, up to the direction perpendicular to the longitudinal cross-section. Next, the shape of each individual island is observed in each cross-section. For the shape of each island, the straight-line distance connecting the leftmost point perpendicular to the thickness direction of the heat-fusible resin layer and the rightmost point perpendicular to that point is defined as the diameter y. For each cross-section, the average of the top 20 diameters y of the island shape, ordered from largest to smallest, is calculated. The direction parallel to the cross-section with the largest average diameter y of the island shape is determined to be the MD (Movement Direction).

[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 a base layer 1, a barrier layer 3, and a heat-fusible resin layer 4 in that order, as shown in Figure 1, for example. 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 needed, for the purpose of improving the adhesion between these layers, as shown in Figures 2 and 3. Also, as shown in Figure 3, 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 3, 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, as for the preferred range of the laminate constituting the exterior material 10 for energy storage devices, for example, it is 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, or about 60 to 120 μm, with about 60 to 155 μm being particularly preferred.

[0024] In the exterior material 10 for energy storage devices, the ratio of the total thickness of the base layer 1, the adhesive layer 2 (optionally provided), the barrier layer 3, the adhesive layer 5 (optionally provided), the heat-fusible resin layer 4, and the surface coating layer 6 (optionally provided) to the thickness (total thickness) of the laminate constituting the exterior material 10 for energy storage devices is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more. For example, if the exterior material 10 for energy storage devices of this disclosure includes a base layer 1, an adhesive layer 2, a barrier layer 3, an adhesive layer 5, and a heat-fusible resin layer 4, the ratio of the total thickness of each of these layers to the thickness (total thickness) of the laminate constituting the exterior material 10 for energy storage devices is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more.

[0025] In the heat seal strength measurement of the exterior material 10 for energy storage devices of this disclosure, which is measured by heat sealing two heat-fusible resin layers 4 together under the conditions of a temperature of 190°C, a surface pressure of 1.0 MPa, and 3 seconds, and then peeling the heat-fusible resin layers 4 together, the following heat seal strength reduction temperature T°C is included within the measurement temperature range of 110°C to 120°C.

[0026] (Heat seal strength reduction temperature T℃) The heat seal strength reduction temperature T℃ is the measurement temperature at which the heat seal strength becomes 35 N / 15 mm or more in the heat seal strength measurement, and at the heat seal strength at the heat seal strength reduction temperature T℃ + 10℃ at which the heat seal strength becomes 10 N / 15 mm or less.

[0027] The heat seal strength at the heat seal strength reduction temperature T℃ should be 35 N / 15 mm or more, but from the viewpoint of more favorably achieving the effects of the present invention, it is preferably about 45 N / 15 mm or more, and more preferably about 50 N / 15 mm or more. Also from the same viewpoint, the heat seal strength is preferably about 80 N / 15 mm or less, and preferably about 70 N / 15 mm or less. Preferred ranges for the heat seal strength include about 35 to 80 N / 15 mm, about 35 to 70 N / 15 mm, about 45 to 80 N / 15 mm, about 45 to 70 N / 15 mm, about 50 to 80 N / 15 mm, and about 50 to 70 N / 15 mm.

[0028] Furthermore, the heat seal strength at the heat seal strength reduction temperature T℃ + 10℃ should be 10N / 15mm or less, but from the viewpoint of more favorably achieving the effects of the present invention, it is preferably about 8N / 15mm or less, and more preferably about 5N / 15mm or less. From a similar viewpoint, the heat seal strength is about 0.5N / 15mm or more. The preferred range for the heat seal strength is about 0.5~10N / 15mm, about 0.5~8N / 15mm, and about 0.5~5N / 15mm.

[0029] The method for measuring heat seal strength, and the method for measuring the temperature range that includes the heat seal strength reduction temperature T℃, are as follows.

[0030] (Measurement of heat seal strength, and measurement of the temperature range including the temperature at which heat seal strength decreases (T℃)) In accordance with the provisions of JIS K7127:1999, the heat seal strength is measured at each measurement temperature (sample temperature) (for example, 25°C, 60°C, 80°C, 100°C, 110°C, 120°C, 130°C, and 140°C). As a test specimen, an outer casing material for energy storage devices is prepared, cut into strips with a width of 15 mm in the TD direction. Specifically, as shown in Figure 5, first the outer casing material for energy storage devices is cut to 60 mm (TD direction) × 200 mm (MD direction) (Figure 5a). Next, the outer casing material for energy storage devices is folded in half in the MD direction at the fold point P (midway in the MD direction) so that the heat-sealable resin layers face each other (Figure 5b). The heat-sealable resin layers are heat-sealed together approximately 10 mm inward from the fold P in the MD direction, under the conditions of a seal width of 7 mm, a temperature of 190°C, a surface pressure of 1.0 MPa, and a sealing time of 3 seconds (Figure 5c). In Figure 5c, the shaded area S is the heat-sealed portion. Next, a test specimen is obtained by cutting in the MD direction (cutting at the position of the dashed line in Figure 5d) so that the width in the TD direction is 15 mm (Figure 5e). Next, the test specimen 13 is left for 2 minutes at each measurement temperature, and in each measurement temperature environment, the heat-sealable resin layer of the heat-sealed portion (heat-fused portion) is peeled off at a speed of 300 mm / min using a tensile testing machine (for example, Shimadzu Corporation, AG-Xplus (product name)) (Figure 6). The maximum strength at the time of peeling is defined as the heat seal strength (N / 15 mm). The distance between chucks is 50 mm. The average value of three measurements is used. From the heat seal strength obtained at each measurement temperature, the measurement temperature range that includes the heat seal strength reduction temperature T℃ specified above (heat seal strength reduction temperature T℃) is determined. Specific examples are shown in the examples.

[0031] From the viewpoint of more favorably achieving the effects of the present invention, the heat seal strength of the exterior material for energy storage devices of the present disclosure, when measured at a measurement temperature of 100°C, is preferably 50 N / 15 mm or more, more preferably 60 N / 15 mm or more, and even more preferably 70 N / 15 mm or more. Also from the same viewpoint, the heat seal strength is preferably 100 N / 15 mm or less, and more preferably 90 N / 15 mm or less. The preferred range for the heat seal strength is approximately 50 to 100 N / 15 mm, approximately 50 to 90 N / 15 mm, approximately 60 to 100 N / 15 mm, approximately 60 to 90 N / 15 mm, approximately 70 to 100 N / 15 mm, and approximately 70 to 90 N / 15 mm.

[0032] Furthermore, from the viewpoint of more favorably achieving the effects of the present invention, the heat seal strength of the exterior material for energy storage devices of the present disclosure, when measured at a measurement temperature of 110°C, is preferably 35 N / 15 mm or more, more preferably 40 N / 15 mm or more, and even more preferably 50 N / 15 mm or more. Also, from the same viewpoint, the heat seal strength is preferably 80 N / 15 mm or less, and more preferably 70 N / 15 mm or less. The preferred range for the heat seal strength is approximately 35-80 N / 15 mm, 35-70 N / 15 mm, 40-80 N / 15 mm, 40-70 N / 15 mm, 50-80 N / 15 mm, and 50-70 N / 15 mm.

[0033] Furthermore, from the viewpoint of more favorably achieving the effects of the present invention, the heat seal strength of the exterior material for energy storage devices of the present disclosure, when measured at a measurement temperature of 120°C, is preferably 2N / 15mm or more, more preferably 5N / 15mm or more. Also, from the same viewpoint, the heat seal strength is preferably 70N / 15mm or less, more preferably 60N / 15mm or less. The preferred range for the heat seal strength is approximately 2-70N / 15mm, 2-60N / 15mm, 5-70N / 15mm, and 5-60N / 15mm.

[0034] Furthermore, from the viewpoint of more favorably achieving the effects of the present invention, the heat seal strength of the exterior material 10 for energy storage devices of the present disclosure, when measured at a measurement temperature of 130°C, is preferably 10N / 15mm or less, more preferably 5N / 15mm or less. Also, from the same viewpoint, the heat seal strength is preferably 0N / 15mm or more, more preferably 1N / 15mm or more. The preferred range for the heat seal strength is approximately 0-10N / 15mm, 0-5N / 15mm, 1-10N / 15mm, and 1-5N / 15mm.

[0035] Furthermore, from the viewpoint of more favorably achieving the effects of the present invention, the Martens hardness, measured by indentation method at a measurement temperature (sample temperature) of 100°C, by pressing a Vickers indenter in the thickness direction from the surface of the heat-fusible resin layer 4 side of the exterior material 10 for the energy storage device of the present disclosure to a depth of 1 μm, is preferably 10.0 MPa or higher, more preferably 11.0 MPa or higher, and even more preferably 12.0 MPa or higher. From a similar viewpoint, the Martens hardness is preferably 25.0 MPa or lower, more preferably 20.0 MPa or lower. Preferred ranges for the Martens hardness include approximately 10.0 to 25.0 MPa, approximately 10.0 to 20.0 MPa, approximately 11.0 to 25.0 MPa, approximately 11.0 to 20.0 MPa, approximately 12.0 to 25.0 MPa, and approximately 12.0 to 20.0 MPa. The Martens hardness at 100°C being within the range described above means that even if gas is generated from within the energy storage device due to heat and the internal pressure begins to rise, the heat-sealable resin layer will not move easily, preventing it from opening at an unexpected temperature. For example, this prevents the outer packaging material for energy storage devices from opening due to gas generated by heating during the baking process in the manufacturing process of energy storage devices. The method for measuring the Martens hardness is as follows.

[0036] (Measurement of Martens hardness) Based on the indentation method, the Martens hardness is measured by pressing a Vickers indenter to a depth of 1 μm in the thickness direction from the surface of the heat-fusible resin layer side of the exterior material for energy storage devices at a measurement temperature (sample temperature) of 100°C. The measurement conditions are as follows. The Martens hardness is calculated from the load-displacement curve obtained by pressing the Vickers indenter. The average of the values ​​obtained for 10 locations on the surface of the heat-fusible resin layer side is used as the measured value. The Martens hardness is calculated as the surface area A (mm²) of the Vickers indenter at the maximum indentation depth of the Vickers indenter. 2 ) calculate the surface area A (mm²) 2 It is obtained by dividing the maximum load F(N) by (F / A). As a measuring device, for example, a Picodenter HM-500 manufactured by Fischer Instruments is used. For example, an exterior material for a power storage device is attached to one side of a slide glass (76 mm x 26 mm x 1 mm) with double-sided adhesive tape attached, so that the heat-sealable resin layer side is on the opposite side of the slide glass, and this is used as a measurement sample. Next, a heating stage is set on an ultramicro hardness tester equipped with a Vickers indenter, and the stage temperature is set to 110°C and the sample is heated for 5 minutes. Next, the surface hardness of the surface on the heat-sealable resin layer side of the measurement sample is measured. <Measurement conditions> • Indenter: Vickers (136° angle between opposite ends of the square pyramid) • Measurement temperature (sample temperature): 100℃ Stage temperature: 110℃ ·Speed: 1.000μm / 10 seconds • Measurement depth: 1.0 μm ·Holding time: 5 seconds • Speed ​​of release after indentation: 1,000 μm / 10 seconds

[0037] Furthermore, the exterior material for energy storage devices of this disclosure is preferably opened between 120°C and 130°C when subjected to the following opening test.

[0038] (Opening test) The exterior material for the energy storage device is cut to a size of 100 mm x 200 mm, and the heat-sealable resin layers are placed facing each other, with the fold made at the center of the long side of the exterior material. Next, the short side is heat-sealed at a temperature of 190°C, a surface pressure of 1.0 MPa, for 3 seconds, with a seal width of 7 mm. Furthermore, the other long side is heat-sealed in the same way, and 2.0 g of water is placed in the resulting bag-like sample. After removing the air from the inside, the opening (long side) is heat-sealed in the same way to create a test sample that seals the water. The test sample is placed in an oven and heated from room temperature (25°C) at a heating rate of 5°C / min until the test sample temperature reaches 130°C, and is held at 130°C for 30 minutes. During the test, when the temperature exceeds 100°C, the internal pressure increases due to the vaporization of water, reaching 140 kPa at 110°C, 200 kPa at 120°C, and 270 kPa at 130°C.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] Among these, polyester and polyamide are preferred as resins for forming the base layer 1.

[0044] 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.

[0045] Furthermore, specific 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] [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.

[0056] 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.

[0057] 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.

[0058] Examples of polyurethane adhesives include polyurethane adhesives comprising a first agent containing a polyol compound and a second agent containing an isocyanate compound. Preferably, a two-component curing type polyurethane adhesive is used, in which a polyol such as polyester polyol, polyether polyol, and acrylic polyol is used as the first agent and an aromatic or aliphatic polyisocyanate is used as the second agent. Another example of a polyurethane adhesive is a polyurethane adhesive comprising a polyurethane compound obtained by pre-reacting a polyol compound with an isocyanate compound and an isocyanate compound. Another example of a polyurethane adhesive is a polyurethane adhesive comprising a polyurethane compound obtained by pre-reacting a polyol compound with an isocyanate compound and an isocyanate compound and an isocyanate compound. Another example of a polyurethane adhesive is a polyurethane adhesive obtained by curing a polyurethane compound obtained by pre-reacting a polyol compound with an isocyanate compound by reacting it with moisture such as air. As the polyol compound, it is preferable to use a polyester polyol having hydroxyl groups on the side chains in addition to the hydroxyl groups at the ends of the repeating units. Examples of the second agent are 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). Also, polyfunctional isocyanate modified compounds derived from one or more of these diisocyanates are used. Furthermore, polymers (e.g., trimers) can be used as polyisocyanate compounds. Examples of such polymers include adducts, biuretes, and nurates. 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 substrate layer 1 even if electrolyte adheres to the sides.

[0059] 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.

[0060] The type of pigment is not particularly 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 dioxide, cadmium, lead, chromium oxide, and iron pigments. Other examples include fine mica powder and fish scale foil.

[0061] Among colorants, carbon black is preferred for, for example, to give the exterior material of an energy storage device a black appearance.

[0062] The average particle size of the pigment is not particularly limited, but for example, it can be 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.

[0063] The pigment content in the adhesive layer 2 is not particularly limited as long as the exterior material for the energy storage device is colored, and for example, it is about 5 to 60% by mass, preferably 10 to 40% by mass.

[0064] The thickness of the adhesive layer 2 is not particularly limited as long as it can bond the substrate layer 1 and the barrier layer 3, but for example, it is about 1 μm or more and about 2 μm or more. Also, the thickness of the adhesive layer 2 is, for example, about 10 μm or less and about 5 μm or less. Furthermore, 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.

[0065] [Colored layer] The colored layer is a layer provided between the base layer 1 and the barrier layer 3 as needed (not shown in the figure). If an adhesive layer 2 is present, the colored layer may be provided between the base layer 1 and the adhesive layer 2, and between the adhesive layer 2 and the barrier layer 3. Alternatively, the colored layer may be provided on the outside of the base layer 1. By providing a colored layer, the exterior material for the energy storage device can be colored.

[0066] The colored layer can be formed, for example, by applying an ink containing a coloring agent to the surface of the substrate layer 1 or the surface of the barrier layer 3. Known coloring agents such as pigments and dyes can be used. In addition, only one type of coloring agent may be used, or two or more types may be mixed. You may use it.

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

[0068] [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.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] Specific examples of austenitic stainless steels that make up stainless steel foil include SUS304, SUS301, and SUS316L, with SUS304 being particularly preferred among these.

[0073] 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. Furthermore, preferred ranges for the thickness of the barrier layer 3 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. Also, the thickness of the stainless steel foil is preferably about 10 μm or more, more preferably about 15 μm or more. Furthermore, preferred ranges for the thickness of 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.

[0074] 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 (e.g., acid resistance, alkali resistance, etc.) to the barrier layer by performing treatments such as hot water modification treatment such as boehmite treatment, chemical conversion treatment, anodizing treatment, plating treatment with nickel or chromium, or corrosion prevention treatment by applying a coating agent to the surface of the barrier layer. Specifically, a corrosion-resistant coating means a coating that improves the acid resistance of the barrier layer (acid-resistant coating), a coating that improves the alkali resistance of the barrier layer (alkali-resistant coating), etc. 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. These processes may also be included in the definition of chemical conversion treatment. Furthermore, if barrier layer 3 has a corrosion-resistant coating, the barrier layer 3 includes the corrosion-resistant coating.

[0075] 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.

[0076] 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. Further, the acrylic resin is also 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.

[0077]

Chemical formula

[0078]

Chemical formula

[0079]

Chemical formula

[0080]

Chemical formula

[0081] 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 a hydroxy group, an alkyl group, or a 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) 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.

[0082] 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.

[0083] 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.

[0084] 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.

[0085] Furthermore, the composition of the corrosion-resistant coating can be analyzed, for example, using time-of-flight secondary ion mass spectrometry.

[0086] 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

[0087] 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. + CePO4 - (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.

[0088] 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.

[0089] [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.

[0090] From the viewpoint of more favorably achieving the effects of the present invention, it is preferable that the heat-fusible resin layer 4 in the exterior material for energy storage devices of the present disclosure exhibits a melting peak temperature of 130°C or lower. From a similar viewpoint, the melting peak temperature is preferably about 100°C or higher, more preferably about 110°C or higher, even more preferably about 120°C or higher, and also preferably about 150°C or lower, more preferably 145°C or lower, and even more preferably 138°C or lower. Preferred ranges for the melting peak temperature include about 100-150°C, about 100-145°C, about 100-138°C, about 100-130°C, about 110-150°C, about 110-145°C, about 110-138°C, about 110-133°C, about 120-150°C, about 120-145°C, about 120-138°C, and about 120-130°C. The number of melting peak temperatures may be one or more. For example, a melting peak temperature of 130°C or lower may be observed in the heat-fusible resin layer 4, and a melting peak temperature exceeding 130°C may also be observed. From the viewpoint of more favorably achieving the effects of the present invention, it is preferable that all melting peak temperatures observed in the heat-fusible resin layer 4 are 145°C or lower. The method for measuring the melting peak temperature is as follows.

[0091] (Measurement of melting peak temperature) A heat-fusible resin layer is obtained from the exterior material of an energy storage device and used as a measurement sample. The melting peak temperature of the measurement sample is measured in accordance with the provisions of JIS K7121:2012 (Method for measuring the transition temperature of plastics (Supplement 1 of JIS K7121:1987)). The measurement is performed using a differential scanning calorimeter (DSC, for example, a differential scanning calorimeter Q200 manufactured by T.A. Instruments).

[0092] Furthermore, from the viewpoint of more favorably achieving the effects of the present invention, the heat-fusible resin layer has a molecular weight (the molecular weight at which the value obtained by differentiating the concentration fraction with respect to the logarithm of the molecular weight is the peak value) of the differential molecular weight distribution curve measured using high-temperature gel permeation chromatography, preferably about 150,000 or more, more preferably about 160,000 or more, even more preferably 165,000 or more, and even more preferably 170,000 or more. Such molecular weights are, for example, about 250,000 or less, about 220,000 or less, about 200,000 or less, etc. The preferred ranges for the molecular weight are approximately 150,000 to 250,000, 150,000 to 220,000, 150,000 to 200,000, 160,000 to 250,000, 160,000 to 220,000, 160,000 to 200,000, 165,000 to 250,000, 165,000 to 220,000, 165,000 to 200,000, 170,000 to 250,000, 170,000 to 220,000, and 170,000 to 200,000. A molecular weight of approximately 150,000 or higher allows the energy storage device to be more effectively sealed by the outer casing material, especially until the energy storage device reaches a high temperature (e.g., around 100°C). Regarding the molecular weight of the resin, the number-average molecular weight (Mn), weight-average molecular weight (Mw), and Mw / Mn are often used. However, the inventors of this disclosure found no clear correlation between the configuration in which the energy storage device is suitably sealed by an outer material for energy storage devices and the configuration in which it is not. In contrast, as described in this disclosure, a clear correlation was found between the peak value of the differential molecular weight distribution curve and the sealing performance.

[0093] (Measurement of molecular weight that corresponds to the peak value of the differential molecular weight distribution curve) A heat-fusible resin layer is obtained from the exterior material of an energy storage device and used as a measurement sample. For each measurement sample, high-temperature gel permeation chromatography (e.g., SSC-7120 HT-GPC System from Senshu Scientific Co., Ltd.) is used to sequentially accumulate the concentration fraction of each molecular weight on the horizontal axis with the molecular weight (logarithmic value) under the following measurement conditions to obtain an integral molecular weight distribution curve. A differential molecular weight distribution curve is obtained by calculating the derivative of the curve at each molecular weight, and the molecular weight at which the peak value on the vertical axis (dw / d(Log(M))) is determined. As shown in the schematic diagram in Figure 8, the differential molecular weight distribution curve is a graph where the horizontal axis is molecular weight and the vertical axis is the value obtained by differentiating the concentration fraction with respect to the logarithmic value of the molecular weight. The molecular weight at the position where the value obtained by differentiating the concentration fraction with respect to the logarithmic value of the molecular weight is highest is the molecular weight at which the peak value of the differential molecular weight distribution curve (see position P in Figure 8) is obtained.

[0094] <Measurement conditions> (Pre-processing) Dissolve the sample in a solvent (o-dichlorobenzene at 145°C). The resulting solution is left to stand for 1 hour, and then stirred for another 1 hour. Next, the solution is pressure filtered through membrane filters with pore sizes of 1.0 μm and 0.5 μm. (measurement) Following the aforementioned pretreatment, a sample is prepared in which the measurement sample is dissolved in a solvent (o-dichlorobenzene), and a differential molecular weight distribution curve is obtained using high-temperature gel permeation chromatography (high-temperature GPC, SSC-7120 HT-GPC System, manufactured by Senshu Scientific Co., Ltd.). The sample injection volume is 300 μL, the guard column is HT-G, the columns are two HT-806M, the column temperature is 145°C, the mobile phase is o-dichlorobenzene (containing 0.025% by mass of BHT (butylated hydroxytoluene)), the flow rate is 1.0 mL / min, the detector is a differential refractometer, the molecular weight calibration is in polystyrene equivalent, and the target molecular weight range is 1,000-20,000,000.

[0095] Furthermore, from the viewpoint of more favorably achieving the effects of the present invention, in the exterior material for energy storage devices of the present disclosure, the difference between the melting peak temperature and the softening point of the heat-fusible resin layer 4 is preferably about 30°C or less, more preferably about 20°C or less, even more preferably about 10°C or less, and even more preferably about 5°C or less. Preferred ranges for this difference include about 0 to 30°C, about 0 to 20°C, about 0 to 10°C, and about 0 to 5°C. Generally, resins that have exceeded their glass transition temperature tend to soften as the temperature increases. When the temperature of the resin exceeds its melting point, the physical properties of the resin change rapidly, and the seal strength at the melting point becomes a very small value. However, even during the process of the resin softening, the seal strength of the heat-fusible resin layer tends to gradually decrease. If the softening of the resin proceeds at a temperature significantly lower than the melting point, there is a possibility that the exterior material for energy storage devices may open at a temperature lower than the desired temperature. Therefore, it is desirable that the difference between the melting peak temperature and the softening point of the heat-fusible resin layer 4 satisfies the above conditions, and that the difference be as small as possible. The method for measuring the melting peak temperature and the softening point of the heat-fusible resin layer 4 is as follows.

[0096] (Measurement of softening point) To measure the softening point of the casing material for energy storage devices, for example, as shown in the conceptual diagram in Figure 7, a probe 11 is first placed on the surface of the heat-fusible resin layer 4 in the cross-section of the casing material for energy storage devices (measurement start A in Figure 7). The cross-section at this time is the portion where the cross-section of the heat-fusible resin layer 4 is exposed, obtained by cutting the casing material in the thickness direction of the casing material for energy storage devices. Figure 7 shows the probe placement position 4a. Cutting can be performed using a commercially available rotary microtome or the like. When measuring the displacement of the casing material for energy storage devices used in batteries containing electrolytes, the portion of the casing material where the heat-fusible resin layer has not yet fused is cut in the thickness direction in the same manner as described above and measured. As an atomic force microscope to which a cantilever with a heating mechanism can be attached, for example, the afm plus system from ANASYS INSTRUMENTS can be used, and as a probe, the ThermaLever AN2-200 cantilever from ANASYS INSTRUMENTS (spring constant 0.5~3N / m) can be used. The tip radius of probe 11 is set to 30 nm or less, the deflection setting of probe 11 is set to -4 V, and the heating rate is set to 5 °C / min. Next, when the probe is heated in this state, the heat from the probe causes the surface of the heat-fusible resin layer 4 to expand, as shown in Figure 7B, pushing up the probe 11, and the position of probe 11 rises above its initial value (the position when the probe temperature is 40 °C). As the heating temperature rises further, the heat-fusible resin layer 4 softens, and as shown in Figure 7C, the probe 11 penetrates the heat-fusible resin layer 4, causing the position of probe 11 to drop. The temperature at which the position drops (the point at which it starts to decrease from rising) was defined as the softening point of the exterior material for the energy storage device. The exterior material for the energy storage device to be measured is at room temperature (25 °C), and the probe heated to 40 °C is placed on the surface of the heat-fusible resin layer 4 to start the measurement.

[0097] 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.

[0098] 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.

[0099] 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.

[0100] 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.

[0101] 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.

[0102] 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.

[0103] 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.

[0104] 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.

[0105] 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.

[0106] 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.

[0107] 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.

[0108] 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.

[0109] [Adhesive layer 5] In the exterior material for energy storage devices of this disclosure, the adhesive layer 5 is a layer provided between the barrier layer 3 (or corrosion-resistant film) and the heat-fusible resin layer 4 as necessary in order to firmly bond them together.

[0110] From the viewpoint of more favorably achieving the effects of the present invention, the adhesive layer 5 is preferably about 120°C or higher, about 130°C or higher, about 140°C or higher, and about 150°C or higher, and also preferably about 170°C or lower and 150°C or lower. In the preferred range, melting peaks are observed in the ranges of approximately 120-170°C, 120-150°C, 130-170°C, 130-150°C, 140-170°C, 140-150°C, and 150-170°C. There may be one or more melting peak temperatures. Furthermore, melting peak temperatures outside the range of 120-170°C may be observed in the adhesive layer 5. However, from the viewpoint of more favorably achieving the effects of the present invention, it is preferable that all melting peak temperatures observed in the adhesive layer 5 are in the range of 120-170°C. The melting peak temperature is measured by the method described in the (Melting Peak Temperature) section above, except that the adhesive layer is obtained from the exterior material for the energy storage device and used as a measurement sample.

[0111] The adhesive layer 5 is formed from a resin capable of bonding the barrier layer 3 and the heat-fusible resin layer 4. A thermoplastic resin is preferably used as the resin for forming the adhesive layer 5. The resin used for forming the adhesive layer 5 preferably contains a polyolefin skeleton, and examples include the polyolefin and acid-modified polyolefin exemplified in the heat-fusible resin layer 4 described above. On the other hand, from the viewpoint of firmly bonding the barrier layer 3 and the adhesive layer 5, it is preferable that the adhesive layer 5 contains an acid-modified polyolefin. Examples of acid-modified components include dicarboxylic acids such as maleic acid, itaconic acid, succinic acid, and adipic acid, as well as their anhydrides, acrylic acid, and methacrylic acid, but maleic anhydride is most preferred in terms of ease of modification and versatility. Furthermore, from the viewpoint of heat resistance of the exterior material for energy storage devices, the olefin component is preferably a polypropylene-based resin, and it is most preferable that the adhesive layer 5 contains maleic anhydride-modified polypropylene.

[0112] 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, the presence of an acid-modified polyolefin in the resin constituting the adhesive layer 5 can be determined, for example, by measuring maleic anhydride-modified polyolefin using infrared spectroscopy, at a wavenumber of 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.

[0113] The thickness of the adhesive layer 5 is preferably about 60 μm or less, about 50 μm or less, or about 45 μm or less. Alternatively, the thickness of the adhesive layer 5 is preferably about 10 μm or more, about 20 μm or more, about 25 μm or more, or about 30 μm or more. Furthermore, the range of the thickness of the adhesive layer 5 is preferably about 10-60 μm, about 10-50 μm, about 10-45 μm, about 20-60 μm, about 20-50 μm, about 20-45 μm, about 25-60 μm, about 25-50 μm, about 25-45 μm, about 30-60 μm, about 30-50 μm, or about 30-45 μm. The adhesive layer 5 can be formed, for example, by extrusion molding of the heat-fusible resin layer 4 and the adhesive layer 5.

[0114] [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.

[0115] The surface coating layer 6 can be formed from a resin such as polyvinylidene chloride, polyester, polyurethane, acrylic resin, or epoxy resin.

[0116] 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.

[0117] Examples of two-component curable polyurethanes include polyurethanes comprising a first agent containing a polyol compound and a second agent containing an isocyanate compound. Preferably, two-component curable polyurethanes include those comprising a polyol such as polyester polyol, polyether polyol, and acrylic polyol as the first agent and an aromatic or aliphatic polyisocyanate as the second agent. Examples of polyurethanes include polyurethanes comprising a polyurethane compound obtained by reacting a polyol compound and an isocyanate compound in advance, and an isocyanate compound. Examples of polyurethanes include polyurethanes comprising a polyurethane compound obtained by reacting a polyol compound and an isocyanate compound in advance, and a polyol compound. Examples of polyurethanes include polyurethanes cured by reacting a polyurethane compound obtained by reacting a polyol compound and an isocyanate compound in advance with moisture such as air. As the polyol compound, it is preferable to use a polyester polyol having hydroxyl groups on the side chains in addition to the hydroxyl groups at the ends of the repeating units. Examples of the second agent 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). Polyfunctional isocyanate modified compounds derived from one or more of these diisocyanates are also possible. Furthermore, polymers (e.g., trimers) can be used as polyisocyanate compounds. Examples of such polymers include adducts, biuretes, and nurates. Furthermore, aliphatic isocyanate compounds refer to isocyanates that have an aliphatic group and no aromatic ring, alicyclic isocyanate compounds refer to isocyanates that have an alicyclic hydrocarbon group, and aromatic isocyanate compounds refer to isocyanates that have an aromatic ring.The surface coating layer 6 is formed of polyurethane, which provides the exterior material for energy storage devices with excellent electrolyte resistance.

[0118] The surface coating layer 6 may contain, as necessary, additives such as the aforementioned lubricants, 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.

[0119] 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.

[0120] 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, and nickel. Additives may be used individually or in combination of two or more. Among these additives, silica, barium sulfate, and titanium oxide are preferred from the viewpoint of dispersion stability and cost. In addition, various surface treatments such as insulation treatment and high-dispersibility treatment may be applied to the surface of the additives.

[0121] 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.

[0122] 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.

[0123] 3. Method for manufacturing exterior materials for energy storage devices The method for manufacturing an exterior material for energy storage devices is not particularly limited, as long as a laminate is obtained by laminating each layer of the exterior material for energy storage devices of this disclosure. At a minimum, a method is provided which involves laminating a base layer 1, a barrier layer 3, and a heat-fusible resin layer 4 in that order. That is, the method for manufacturing an exterior material for energy storage devices of this disclosure includes at least a step of laminating a base layer, a barrier layer, and a heat-fusible resin layer in that order to obtain a laminate. In a heat seal strength measurement of the exterior material for energy storage devices, which is measured by heat sealing the heat-fusible resin layers together under the conditions of a temperature of 190°C, a surface pressure of 1.0 MPa, and 3 seconds, and then peeling the heat-fusible resin layers together, the heat seal strength reduction temperature T°C is included within the measurement temperature range of 110°C to 120°C.

[0124] An example of a method for manufacturing the exterior material for energy storage devices of the present invention is as follows. First, a laminate (hereinafter sometimes referred to as "laminated body A") is formed by sequentially laminating a base material 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 material 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 material layer 1 is laminated and the adhesive layer 2 is cured.

[0125] 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.

[0126] 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.

[0127] As described above, a laminate is formed comprising, as necessary, a surface coating layer 6, a base material layer 1, an adhesive layer 2 as necessary, a barrier layer 3, an adhesive layer 5 as necessary, and a heat-fusible resin layer 4 in this order. In order to strengthen the adhesion of the adhesive layer 2 and adhesive layer 5 as necessary, the laminate may be subjected to further heat treatment.

[0128] 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.

[0129] 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.

[0130] 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). The packaging can be formed by overlapping the heat-sealable resin layers of two energy storage device casing materials facing each other and heat-sealing the periphery of the overlapped casing materials. Alternatively, as shown in the example in Figure 4, one energy storage device casing material can be folded and overlapped, and the periphery can be heat-sealed to form the packaging. When folding and overlapping, as shown in the example in Figure 4, the edges other than the folded edge can be heat-sealed to form a three-sided seal, or the edges can be folded to form a flange and then sealed on all four sides. Furthermore, the energy storage device casing material may have a recess for housing the energy storage device element formed by deep drawing or stretch molding. As shown in the example in Figure 4, one energy storage device casing material may have a recess while the other does not, or the other energy storage device casing material may also have a recess.

[0131] 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 types of secondary batteries to which the casing material for energy storage devices disclosed herein can be applied are 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]

[0132] 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.

[0133] <Manufacturing of exterior materials for energy storage devices> Examples 1-4 A stretched nylon (ONy) film (25 μm thick) was prepared as the base layer. Aluminum foil (JIS H4160:1994 A8021H-O (40 μm thick)) was prepared as the barrier layer. Next, the base layer and barrier layer were bonded using a two-component urethane adhesive (polyol compound and aromatic isocyanate compound) by dry lamination, and an aging treatment was performed to create a laminate consisting of a base layer (25 μm thick), an adhesive layer (3 μm thick after curing), and a barrier layer (40 μm thick). Both sides of the aluminum foil were treated with a chemical conversion solution. 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 This was achieved by applying the coating to both sides of the aluminum foil using the roll-coating method and then baking it to achieve the desired (dry mass).

[0134] Next, a maleic anhydride-modified polypropylene (PPa1 or PPa2 in Table 1, respectively) as an adhesive layer (23 μm thick) and a random polypropylene (PP1, PP2, PP3, or PP4 in Table 1, respectively) as a heat-fusible resin layer (22 μm thick) were co-extruded onto the barrier layer of the laminate obtained above, thereby obtaining an exterior material for energy storage devices in which a base layer (25 μm thick) / adhesive layer (3 μm) / barrier layer (40 μm) / adhesive layer (23 μm) / heat-fusible resin layer (22 μm) were laminated in that order.

[0135] In Examples 1-4, the random polypropylene PP1, PP2, PP3, or PP4 used for the heat-fusible resin layer was selected based on its lower melting peak temperature and higher molecular weight at the peak of the differential molecular weight distribution curve compared to the polypropylene used for the heat-fusible resin layer of the exterior material. Furthermore, in order to suppress the thermal decomposition of the random polypropylene during the formation of the heat-fusible resin layer by co-extrusion, the co-extrusion was performed under lower-temperature conditions than usual, thereby suppressing the decrease in molecular weight at the peak of the differential molecular weight distribution curve.

[0136] Example 5 Except for setting the temperature for co-extruding the maleic anhydride-modified polypropylene (PPa1 in Table 1) as the adhesive layer (23 μm thick) and the random polypropylene (PP1 in Table 1) as the heat-fusible resin layer (22 μm thick) onto the barrier layer to 30°C higher than in Example 1, an exterior material for an energy storage device was obtained in which a base layer (25 μm thick) / adhesive layer (3 μm) / barrier layer (40 μm) / adhesive layer (23 μm) / heat-fusible resin layer (22 μm) were laminated in the same manner as in Example 1.

[0137] Example 6 Except for setting the temperature for co-extruding the maleic anhydride-modified polypropylene (PPa1 in Table 1) as the adhesive layer (23 μm thick) and the random polypropylene (PP2 in Table 1) as the heat-fusible resin layer (22 μm thick) onto the barrier layer to 30°C higher than in Example 2, an exterior material for an energy storage device was obtained in which a base layer (25 μm thick) / adhesive layer (3 μm) / barrier layer (40 μm) / adhesive layer (23 μm) / heat-fusible resin layer (22 μm) were laminated in the same manner as in Example 2.

[0138] Comparative Example 1 A laminate consisting of a base layer (thickness 25 μm), an adhesive layer (thickness after curing 3 μm), and a barrier layer (thickness 40 μm) was prepared in the same manner as in Examples 1-6. Next, this laminate and an unstretched polypropylene film (thickness 40 μm) as a heat-sealable resin layer were bonded using an adhesive containing polyolefin resin and an isocyanate compound as curing components to obtain an exterior material for an energy storage device in which a base layer (thickness 25 μm), adhesive layer (3 μm), barrier layer (40 μm), adhesive layer (3 μm), and heat-sealable resin layer (40 μm) were laminated in that order.

[0139] The melting peak temperatures of the adhesive layer or heat-fusible resin layer in Examples 1-6 and Comparative Example 1 are shown in Table 1. These melting peak temperatures were measured using the following method.

[0140] (Measurement of melting peak temperature) Adhesive layers and heat-fusible resin layers were obtained from exterior materials for energy storage devices and used as measurement samples. For each measurement sample, the melting peak temperature was measured in accordance with the provisions of JIS K7121:2012 (Method for measuring transition temperature of plastics (Supplement 1 to JIS K7121:1987)). The measurements were performed using a differential scanning calorimeter (DSC, Q200 differential scanning calorimeter manufactured by T.A. Instruments).

[0141] (Measurement of molecular weight that corresponds to the peak value of the differential molecular weight distribution curve) A heat-fusible resin layer was obtained from the exterior material of an energy storage device and used as a measurement sample. For each measurement sample, high-temperature gel permeation chromatography (high-temperature GPC, SSC-7120 HT-GPC System, manufactured by Senshu Science Co., Ltd.) was used, and the concentration fraction of each molecular weight was sequentially accumulated on the horizontal axis with the molecular weight (logarithmic value) under the following measurement conditions to obtain an integral molecular weight distribution curve. By calculating the derivative of the curve at each molecular weight, a differential molecular weight distribution curve was obtained, and the molecular weight at which the peak value on the vertical axis (dw / d(Log(M))) was determined. As shown in the schematic diagram in Figure 8, the differential molecular weight distribution curve is a graph where the horizontal axis is molecular weight and the vertical axis is the value obtained by differentiating the concentration fraction with respect to the logarithmic value of the molecular weight. The molecular weight at the position where the value obtained by differentiating the concentration fraction with respect to the logarithmic value of the molecular weight is highest is the molecular weight at which the peak value of the differential molecular weight distribution curve (see position P in Figure 8) is obtained.

[0142] <Measurement conditions> (Pre-processing) Dissolve the sample in a solvent (o-dichlorobenzene at 145°C). The resulting solution is left to stand for 1 hour, and then stirred for another 1 hour. Next, the solution is pressure filtered through membrane filters with pore sizes of 1.0 μm and 0.5 μm. (measurement) Following the aforementioned pretreatment, a sample is prepared in which the measurement sample is dissolved in a solvent (o-dichlorobenzene), and a differential molecular weight distribution curve is obtained using high-temperature gel permeation chromatography (high-temperature GPC, SSC-7120 HT-GPC System, manufactured by Senshu Scientific Co., Ltd.). The sample injection volume is 300 μL, the guard column is HT-G, the columns are two HT-806M, the column temperature is 145°C, the mobile phase is o-dichlorobenzene (containing 0.025% by mass of BHT (butylated hydroxytoluene)), the flow rate is 1.0 mL / min, the detector is a differential refractometer, the molecular weight calibration is in polystyrene equivalent, and the target molecular weight range is 1,000-20,000,000.

[0143] (Measurement of softening point) To measure the softening point of the exterior material for energy storage devices, as shown in the conceptual diagram in Figure 7, for example, a probe 11 was first placed on the surface of the heat-fusible resin layer 4 in the cross-section of the exterior material for energy storage devices (measurement start A in Figure 7). The cross-section at this time is the portion where the cross-section of the heat-fusible resin layer 4 is exposed, obtained by cutting the exterior material for energy storage devices in the thickness direction. Figure 7 shows the probe placement position 4a. The cutting was performed using a commercially available rotary microtome. As an atomic force microscope that can be fitted with a cantilever with a heating mechanism, an afm plus system manufactured by ANASYS INSTRUMENTS was used, and as the probe, an ANASYS INSTRUMENTS ThermaLever AN2-200 cantilever (spring constant 0.5~3N / m) was used. The tip radius of the probe 11 was 30 nm or less, the deflection setting of the probe 11 was -4V, and the heating rate was 5°C / min. Next, when the probe was heated in this state, the heat from the probe caused the surface of the heat-fusible resin layer 4 to expand, as shown in Figure 7B, pushing up the probe 11, and the position of the probe 11 rose above its initial value (the position when the probe temperature was 40°C). As the heating temperature increased further, the heat-fusible resin layer 4 softened, and as shown in Figure 7C, the probe 11 pierced the heat-fusible resin layer 4, causing the position of the probe 11 to drop. The temperature at which the position dropped (the point at which it began to decrease after rising) was defined as the softening point of the exterior material for the energy storage device. The exterior material for the energy storage device to be measured was at room temperature (25°C), and the measurement was started by placing the probe, heated to 40°C, on the surface of the heat-fusible resin layer 4.

[0144] In Example 1, the difference between the melting peak temperature and the softening point of the heat-fusible resin layer was 3°C. In Example 5, the difference between the melting peak temperature and the softening point of the heat-fusible resin layer was 2°C.

[0145] (Measurement of heat seal strength, and measurement of the temperature range including the temperature at which heat seal strength decreases (T℃)) In accordance with the provisions of JIS K7127:1999, the seal strength of the exterior material for energy storage devices at each measurement temperature (sample temperature) listed in Table 1 was measured as follows. As test specimens, the exterior material for energy storage devices was prepared by cutting it into strips with a width of 15 mm in the TD direction. Specifically, as shown in Figure 5, first, each exterior material for energy storage devices was cut to 60 mm (TD direction) × 200 mm (MD direction) (Figure 5a). Next, the exterior material for energy storage devices was folded in half in the MD direction at the fold point P (midway in the MD direction) so that the heat-sealable resin layers faced each other (Figure 5b). The heat-sealable resin layers were heat-sealed together approximately 10 mm inward from the fold point P in the MD direction under the conditions of a seal width of 7 mm, a temperature of 190°C, a surface pressure of 1.0 MPa, and a duration of 3 seconds (Figure 5c). In Figure 5c, the shaded area S is the heat-sealed portion. Next, the material was cut in the MD direction (at the position of the dashed line in Figure 5d) so that the width in the TD direction was 15 mm (Figure 5e). Then, the test piece 13 was left for 2 minutes at each measurement temperature, and in each measurement temperature environment, the heat-fusible resin layer of the heat-sealed part (heat-fused part) was peeled off at a speed of 300 mm / min using a tensile testing machine (Shimadzu Corporation, AG-Xplus (product name)) (Figure 6). The maximum strength at the time of peeling was defined as the heat seal strength (N / 15 mm). The distance between the chucks was 50 mm. The average value of three measurements was used. The results are shown in Table 1. Also, the temperature range in which the heat seal strength reduction temperature T℃ exists is shown in Table 1.

[0146] (Measurement of Martens hardness) Based on the indentation method, the Martens hardness was measured by pressing a Vickers indenter to a depth of 1 μm in the thickness direction from the surface of the heat-fusible resin layer side of each energy storage device exterior material at a measurement temperature (sample temperature) of 100°C. The measurement conditions were as follows. The Martens hardness was calculated from the load-displacement curve obtained by pressing the Vickers indenter. As the measured value, the average obtained from 10 locations on the surface of the heat-fusible resin layer side was adopted. The Martens hardness was calculated as the surface area A (mm²) of the Vickers indenter at the maximum indentation depth of the Vickers indenter. 2 ) calculate the surface area A (mm²) 2It is determined by dividing the maximum load F(N) by (F / A). The details of the measurement method for the Martens hardness of the surface of the heat-fusible resin layer are as follows. A Picodenter HM-500 manufactured by Fischer Instruments was used as the measuring device. An exterior material for an energy storage device was attached to one side of a slide glass (76 mm × 26 mm × 1 mm) with double-sided adhesive tape attached, so that the heat-fusible resin layer side was on the opposite side of the slide glass, and this was used as the measurement sample. Next, a heating stage was set up in an ultramicrohardness tester equipped with a Vickers indenter, and the sample was heated for 5 minutes with the stage temperature set to 110°C. Next, the surface hardness of the surface on the heat-fusible resin layer side of the measurement sample was measured. The results are shown in Table 2. <Measurement conditions> • Indenter: Vickers (136° angle between opposite ends of the square pyramid) • Measurement temperature (sample temperature): 100℃ Stage temperature: 110℃ ·Speed: 1.000μm / 10 seconds • Measurement depth: 1.0 μm ·Holding time: 5 seconds • Speed ​​of release after indentation: 1,000 μm / 10 seconds

[0147] (Opening test) The exterior material for the energy storage device was cut to a size of 100 mm x 200 mm, and the heat-sealable resin layers were placed facing each other, with the fold made at the center of the long side of the exterior material. Next, the short side was heat-sealed at a temperature of 190°C, a surface pressure of 1.0 MPa, for 3 seconds, with a seal width of 7 mm. Furthermore, the other long side was heat-sealed in the same manner, and 2.0 g of water was placed in the resulting bag-like sample. The opening side (long side) was then heat-sealed in the same manner to create a test sample that sealed the water. The test sample was placed in an oven and heated from room temperature (25°C) at a heating rate of 5°C / min until the test sample temperature reached 130°C, and was held at 130°C for 30 minutes. The opening of the exterior material for the energy storage device due to the increase in internal pressure was evaluated according to the following criteria. The results are shown in Table 1. A: The product was opened while the temperature was being raised between 120°C and 130°C, or opened while being held at 130°C for 30 minutes. B: Opened at a temperature between 110°C and 120°C. C: The product was not opened after being held at 130°C for 30 minutes, or it was opened at a temperature below 110°C.

[0148] [Table 1]

[0149] In Table 1, the notation "122 / 134" means that the melting peak temperatures were observed at 122°C and 134°C. Similarly, the notation "140 / 160" means that the melting peak temperatures were observed at 140°C and 160°C.

[0150] [Table 2]

[0151] In the heat seal strength measurement of the exterior material for energy storage devices of Examples 1-6, the predetermined heat seal strength reduction temperature T℃ falls within the measurement temperature range of 110℃ to 120℃ when the heat seal strength reduction temperature is measured by heat sealing the heat-fusible resin layers together under the conditions of a temperature of 190℃, a surface pressure of 1.0 MPa, and 3 seconds, and then peeling the heat seal strength reduction temperature T℃. In the exterior material for energy storage devices of Examples 1-6, it is understood that the exterior material for energy storage devices is sealed by the exterior material until the energy storage device reaches a high temperature of about 100℃, and when the energy storage device reaches a high temperature of 120℃ to 130℃ and the internal pressure rises excessively, the exterior material for energy storage devices opens, allowing gas generated inside the energy storage device to be released to the outside. In particular, as is clear from Table 1, Examples 1 and 5, and Examples 2 and 6, each used the same resin (PPa and PP1 or PP2) for the adhesive layer and the heat-sealable resin layer, respectively. Furthermore, despite the fact that the melting peak temperature of the heat-sealable resin layer was consistently low at 125°C, the heat-sealable resin layers of the exterior materials for energy storage devices in Examples 1 and 2 had a higher molecular weight at the peak of the differential molecular weight distribution curve and exhibited higher heat seal strength at 100°C than the heat-sealable resin layers of the exterior materials for energy storage devices in Examples 5 and 6.

[0152] If the predetermined heat seal strength reduction temperature T℃ is 130℃ or higher, it is considered that stable opening will not occur between 120℃ and 130℃ in the opening test evaluation.

[0153] As described above, this disclosure provides inventions in the following embodiments. Item 1. An exterior material for an energy storage device, comprising a laminate comprising, at least, a base layer, a barrier layer, and a heat-fusible resin layer in this order, The exterior material for the energy storage device is an exterior material for an energy storage device in which, in a heat seal strength measurement performed by heat sealing the heat-fusible resin layers together under the conditions of a temperature of 190°C, a surface pressure of 1.0 MPa, and 3 seconds, and then peeling off the heat-fusible resin layers together, the heat seal strength reduction temperature T°C is included within the measurement temperature range of 110°C to 120°C. (Heat seal strength reduction temperature T℃) In the heat seal strength measurement described above, the measurement temperature at which the heat seal strength is 35 N / 15 mm or more, and at which the heat seal strength at the heat seal strength reduction temperature T℃ + 10℃ is 10 N / 15 mm or less. Item 2. The heat-fusible resin layer is an exterior material for an energy storage device as described in Item 1, wherein a melting peak temperature of 130°C or lower is observed. Item 3. The heat-fusible resin layer has a molecular weight of 150,000 or more, which is the peak value of the differential molecular weight distribution curve measured using high-temperature gel permeation chromatography, as an exterior material for an energy storage device according to Item 1 or 2. Item 4. The resin constituting the heat-fusible resin layer is an exterior material for an energy storage device according to any one of items 1 to 3, having a polyolefin skeleton. Item 5. The resin constituting the heat-fusible resin layer includes polypropylene, wherein the exterior material for an energy storage device is as described in any one of items 1 to 4. Item 6. An adhesive layer is provided between the barrier layer and the heat-fusible resin layer. The resin constituting the adhesive layer is an exterior material for an energy storage device according to any one of claims 1 to 5, having a polyolefin skeleton. Item 7. The exterior material for an energy storage device according to Item 6, wherein the adhesive layer exhibits a melting peak in the range of 120°C to 170°C. Item 8. The exterior material for energy storage devices according to item 6 or 7, wherein the resin constituting the adhesive layer includes acid-modified polypropylene. Item 9. An exterior material for an energy storage device according to any one of items 1 to 8, wherein the Martens hardness, measured by pressing a Vickers indenter to a depth of 1 μm in the thickness direction from the surface of the heat-fusible resin layer side of the exterior material for the energy storage device at a measurement temperature of 100°C based on the indentation method, is 10.0 MPa or higher. Item 10. An exterior material for an energy storage device according to any one of items 1 to 9, wherein the difference between the melting peak temperature and the softening point of the heat-fusible resin layer is 30°C or less. Item 11. The process includes at least a step of obtaining a laminate by laminating a base layer, a barrier layer, and a heat-fusible resin layer in this order, A method for manufacturing an exterior material for an energy storage device, wherein the exterior material for the energy storage device is measured by heat sealing the heat-fusible resin layers together under the conditions of a temperature of 190°C, a surface pressure of 1.0 MPa, and 3 seconds, and then peeling the heat-fusible resin layers apart, and the heat seal strength reduction temperature T°C is included within the range of measurement temperature of 110°C to 120°C. (Heat seal strength reduction temperature T℃) In the heat seal strength measurement described above, the measurement temperature at which the heat seal strength is 35 N / 15 mm or more, and at which the heat seal strength at the heat seal strength reduction temperature T℃ + 10℃ is 10 N / 15 mm or less. Item 12. 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 an energy storage device as described in any one of items 1 to 10. [Explanation of Symbols]

[0154] 1 Base material layer 2 Adhesive 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, comprising at least a laminate comprising a base layer, a barrier layer, and a heat-sealable resin layer in this order, In the heat seal strength measurement of the exterior material for the energy storage device, which is measured by heat sealing the heat-fusible resin layers together under the conditions of a temperature of 190°C, a surface pressure of 1.0 MPa, and 3 seconds, and then peeling off the heat-fusible resin layers together, the heat seal strength reduction temperature T°C is included within the measurement temperature range of 110°C to 120°C. The aforementioned exterior material for energy storage devices is an exterior material for energy storage devices in which, in the heat seal strength measurement, the heat seal strength at a measurement temperature of 120°C is 2 N / 15 mm or more. (Heat seal strength reduction temperature T°C) In the heat seal strength measurement described above, the measurement temperature at which the heat seal strength is 35 N / 15 mm or more, and at which the heat seal strength at the heat seal strength reduction temperature T°C + 10°C is 10 N / 15 mm or less.

2. The heat-sealable resin layer has a molecular weight of 150,000 or more, which is the peak value of the differential molecular weight distribution curve measured using high-temperature gel permeation chromatography, as described in claim 1, for exterior material for energy storage devices.

3. An exterior material for an energy storage device, comprising a laminate comprising at least a base layer, a barrier layer, and a heat-sealable resin layer in this order, In the heat seal strength measurement of the exterior material for the energy storage device, which is measured by heat sealing the heat-fusible resin layers together under the conditions of a temperature of 190°C, a surface pressure of 1.0 MPa, and 3 seconds, and then peeling off the heat-fusible resin layers together, the heat seal strength reduction temperature T°C is included within the measurement temperature range of 110°C to 120°C. The heat-sealable resin layer is an exterior material for energy storage devices, wherein the molecular weight at which the differential molecular weight distribution curve, measured using high-temperature gel permeation chromatography, reaches its peak value is 150,000 or more. (Heat seal strength reduction temperature T°C) In the heat seal strength measurement described above, the measurement temperature at which the heat seal strength is 35 N / 15 mm or more, and at which the heat seal strength at the heat seal strength reduction temperature T°C + 10°C is 10 N / 15 mm or less.

4. The heat-sealable resin layer exhibits a melting peak temperature of 130°C or lower, as described in any one of claims 1 to 3, for use as an exterior material for an energy storage device.

5. The resin constituting the heat-sealable resin layer has a polyolefin skeleton, as described in any one of claims 1 to 4, for exterior material for energy storage devices.

6. The resin constituting the heat-sealable resin layer includes polypropylene, as described in any one of claims 1 to 5, for use as an exterior material for an energy storage device.

7. An adhesive layer is provided between the barrier layer and the heat-fusible resin layer. The resin constituting the adhesive layer has a polyolefin skeleton, as described in any one of claims 1 to 6, for exterior material for energy storage devices.

8. The exterior material for an energy storage device according to claim 7, wherein the adhesive layer exhibits a melting peak in the range of 120°C to 170°C.

9. The exterior material for an energy storage device according to claim 7 or 8, wherein the resin constituting the adhesive layer includes acid-modified polypropylene.

10. The exterior material for an energy storage device according to any one of claims 1 to 9, wherein the Martens hardness, measured by pressing a Vickers indenter to a depth of 1 μm in the thickness direction from the surface of the heat-fusible resin layer side of the exterior material for the energy storage device at a measurement temperature of 100°C based on the indentation method, is 10.0 MPa or more.

11. The exterior material for an energy storage device according to any one of claims 1 to 10, wherein the difference between the melting peak temperature and the softening point of the heat-fusible resin layer is 30°C or less.

12. The process includes at least a step of obtaining a laminate by laminating a base layer, a barrier layer, and a heat-fusible resin layer in this order, In the heat seal strength measurement of the exterior material for an energy storage device composed of the aforementioned laminate, the heat seal strength reduction temperature T°C is included within the measurement temperature range of 110°C to 120°C, where the heat seal strength reduction temperature T°C is measured by heat sealing the heat-fusible resin layers together under the conditions of a temperature of 190°C, a surface pressure of 1.0 MPa, and 3 seconds, and then peeling off the heat-fusible resin layers together. The method for manufacturing an exterior material for an energy storage device, wherein the exterior material for the energy storage device has a heat seal strength of 2 N / 15 mm or more when the measurement temperature is 120°C in the heat seal strength measurement. (Heat seal strength reduction temperature T°C) In the heat seal strength measurement described above, the measurement temperature at which the heat seal strength is 35 N / 15 mm or more, and at which the heat seal strength at the heat seal strength reduction temperature T°C + 10°C is 10 N / 15 mm or less.

13. The process comprises a step of obtaining a laminate by laminating a base layer, a barrier layer, and a heat-fusible resin layer in this order, In the heat seal strength measurement of the exterior material for an energy storage device composed of the aforementioned laminate, the heat seal strength reduction temperature T°C is included within the measurement temperature range of 110°C to 120°C, where the heat seal strength reduction temperature T°C is measured by heat sealing the heat-fusible resin layers together under the conditions of a temperature of 190°C, a surface pressure of 1.0 MPa, and 3 seconds, and then peeling off the heat-fusible resin layers together. A method for manufacturing an exterior material for an energy storage device, wherein the heat-sealable resin layer has a molecular weight of 150,000 or more, which is the peak value of the differential molecular weight distribution curve measured using high-temperature gel permeation chromatography. (Heat seal strength reduction temperature T°C) In the heat seal strength measurement described above, the measurement temperature at which the heat seal strength is 35 N / 15 mm or more, and at which the heat seal strength at the heat seal strength reduction temperature T°C + 10°C is 10 N / 15 mm or less.

14. 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 11.

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