Resin film for energy storage devices, energy storage devices, and methods for manufacturing the same.

Abstract

A resin film for energy storage devices, The resin film for the energy storage device is composed of a laminate including at least a base film and a pressure-sensitive adhesive layer. The pressure-sensitive adhesive layer constitutes at least one surface of the resin film for the energy storage device, The pressure-sensitive adhesive layer is a resin film for an energy storage device, partially provided on the base film.

Description

[Technical Field]

[0001] This disclosure relates to resin films for energy storage devices, energy storage devices, and methods for manufacturing the same. [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 [Overview of the project] [Problems that the invention aims to solve]

[0007] If a malfunction occurs in the energy storage device, the gas generated inside the device will be released to the outside as the internal pressure of the device rises, causing the sealing portion of the outer casing (for example, the portion where the aforementioned heat-sealable resin layer is heat-sealed) to open.

[0008] In energy storage devices, the sealing area of ​​the outer casing is large, making it difficult to predict in advance where gases generated inside the energy storage device will be discharged.

[0009] Therefore, the inventors of this disclosure have worked to develop a technology in which, in an energy storage device having a structure in which an energy storage device element is sealed by an outer casing, the energy storage device will appropriately open at the position of the resin film when the internal temperature or internal pressure of the energy storage device rises, by arranging a resin film.

[0010] However, the inventors of this disclosure faced the problem that it is difficult to fix such resin films with high positional accuracy during the manufacturing of energy storage devices.

[0011] Under these circumstances, the primary objective of this disclosure is to provide a resin film for energy storage devices that has a structure in which energy storage device elements are sealed by an outer casing, and that can be fixed with high positional accuracy during the manufacturing of the energy storage device. Furthermore, the primary objective of this disclosure is to provide an energy storage device including the resin film for energy storage devices and a method for manufacturing the same. [Means for solving the problem]

[0012] The inventors of the present disclosure have conducted intensive studies to solve the above problems. As a result, it has been found that the resin film for a power storage device is composed of a laminate including at least a base film and a pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer forms at least one surface of the resin film for a power storage device, and by partially providing the pressure-sensitive adhesive layer on the base film, the resin film can be fixed with high positional accuracy during the manufacture of the power storage device.

[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. A resin film for a power storage device, wherein the resin film for a power storage device is composed of a laminate including at least a base film and a pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer forms at least one surface of the resin film for a power storage device, and the pressure-sensitive adhesive layer is partially provided on the base film.

Effects of the Invention

[0014] According to the present disclosure, there is provided a resin film for a power storage device having a structure in which a power storage device element is sealed by an exterior body, and which can be fixed with high positional accuracy during the manufacture of the power storage device. Further, according to the present disclosure, there are provided a power storage device using the resin film and a method for manufacturing the same.

Brief Description of the Drawings

[0015] [Figure 1] It is a schematic diagram showing an example of a cross-sectional structure of the resin film 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 resin film 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 resin film for a power storage device of the present disclosure. [Figure 4]It is a schematic diagram showing an example when the resin film for a power storage device of the present disclosure is viewed in a plan view. [Figure 5] It is a schematic diagram showing an example when the resin film for a power storage device of the present disclosure is viewed in a plan view. [Figure 6] It is a schematic diagram showing an example of a cross-sectional structure of an exterior material for a power storage device of the present disclosure. [Figure 7] It is a schematic plan view showing an example of a power storage device of the present disclosure. [Figure 8] It is a schematic diagram showing an example of a cross-sectional structure at line A - A' in FIG. 7. [Figure 9] It is a schematic perspective view showing an example of a power storage device of the present disclosure. [Figure 10] It is a schematic diagram showing an example of a cross-sectional structure at line A - A' in FIG. 9. [Figure 11] It is a schematic cross-sectional view showing an example of a power storage device of the present disclosure. [Figure 12] It is a schematic cross-sectional view showing an example of a power storage device of the present disclosure.

Mode for Carrying Out the Invention

[0016] The resin film for a power storage device of the present disclosure is composed of at least a laminate including a base film and a pressure-sensitive adhesive layer. The pressure-sensitive adhesive layer constitutes at least one surface of the resin film for a power storage device, and the pressure-sensitive adhesive layer is partially provided on the base film. The resin film for a power storage device of the present disclosure can be fixed with high positional accuracy during the manufacture of the power storage device by having such a configuration.

[0017] The resin film 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. In numerical ranges described in stages in this disclosure, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. Alternatively, upper and lower limits, upper and lower limits, or lower limits described separately may be combined to form numerical ranges. Furthermore, in numerical ranges described in this disclosure, the upper or lower limit value described in one numerical range may be replaced with the values ​​shown in the examples.

[0018] [Resin film for energy storage devices] As shown in Figures 1 to 5, the resin film 1 for energy storage devices of this disclosure (hereinafter sometimes abbreviated as "resin film 1") is composed of a laminate including at least a base film 11 and a pressure-sensitive adhesive layer 12. In the resin film 1 for energy storage devices, the pressure-sensitive adhesive layer 12 constitutes at least one surface of the resin film 1 for energy storage devices. Furthermore, the pressure-sensitive adhesive layer 12 is partially provided on the base film 11.

[0019] In the resin film 1 for energy storage devices of this disclosure, a pressure-sensitive adhesive layer 12 constituting at least one surface is partially provided on the base film 11, making it possible to temporarily bond (temporarily fix) the resin film 1 by the pressure-sensitive adhesive force of the pressure-sensitive adhesive layer 12. As a result, the resin film 1 can be fixed with high positional accuracy during the manufacturing of the energy storage device.

[0020] Furthermore, in the resin film 1 for energy storage devices of this disclosure, the pressure-sensitive adhesive layer 12 is partially provided on the base film 11. Therefore, when the internal temperature or internal pressure of the energy storage device rises, the design allows the energy storage device to be opened at the location of the base film 11 where the pressure-sensitive adhesive layer 12 is not provided. Thus, when the internal temperature or internal pressure of the energy storage device rises, the energy storage device is opened appropriately at the location of the resin film 1.

[0021] The temperature at which the resin film 1 opens the energy storage device is, for example, about 60°C or higher, preferably about 70°C or higher, more preferably about 80°C or higher, and also, for example, about 160°C or lower, preferably about 140°C or lower, more preferably about 120°C or lower. Preferred ranges include about 60-160°C, about 60-140°C, about 60-120°C, about 70-160°C, about 70-140°C, about 70-120°C, about 80-160°C, about 80-140°C, and about 80-120°C.

[0022] Furthermore, the resin film for energy storage devices of this disclosure has a seal strength A (N / 15mm) at an opening temperature A determined by the following opening test, preferably 50N / 15mm or less, more preferably 40N / 15mm or less, and even more preferably 30N / 15mm or less, with a lower limit of, for example, 1.0N / 15mm or more, 2.0N / 15mm or more, and a preferred range of characteristics such as 1.0~50N / 15mm, 1.0~40N / 15mm, 1.0~30N / 15mm, 2.0~50N / 15mm, 2.0~40N / 15mm, and 2.0~30N / 15mm.

[0023] <Measurement conditions for seal strength A and B> The opening temperature A used when measuring seal strength A is determined by performing the following opening test. (Opening test) Prepare one 153μm thick outer casing material for an energy storage device (8cm wide x 19cm long) with a total thickness of 153μm, consisting of a base layer (PET (12μm thick) / adhesive (3μm thick) / nylon (15μm thick)) / adhesive layer (3μm thick) / barrier layer (aluminum alloy foil, 40μm thick) / adhesive layer (maleic anhydride modified polypropylene, 40μm thick) / heat-sealable resin layer (polypropylene, peak melting temperature 140℃, 40μm thick). Fold the outer casing material in half so that the heat-sealable resin layer is on the inside, and make a φ11mm hole in one place on one side (exactly in the center of the 8cm wide x 9.5cm long rectangle). Attach a jig at the location of the hole for installing a tube to supply air into the sample during the opening test. Next, place the resin film for the energy storage device between the heat-sealable resin layers on the short side (horizontal). The size of the resin film for the energy storage device shall be 3 cm wide x 1.5 cm high. The exterior material for the energy storage device and the resin film for the energy storage device shall be positioned so that their widths and heights match. More specifically, horizontally, the centers of the exterior material and the resin film for the energy storage device shall be aligned, and vertically, the short side of the resin film for the energy storage device, which is 3 cm long, shall be aligned with the short side of the resin film for the energy storage device, which is the short side of the resin film for the energy storage device, which is the short side of the resin film for the energy storage device, which is the short side of the resin film for the energy storage device, and the two long sides of the exterior material for the energy storage device shall be heat-sealed under the conditions of a pressure of 0.5 MPa, a temperature of 190°C, 3 seconds, and a seal width of 7 mm, to create a test sample. At this time, both sides of the resin film for the energy storage device shall be heat-sealed to the heat-sealable resin layer. A thermocouple shall be attached to the test sample, and it shall be placed in an oven. Air shall be blown into the test sample, and the pressure shall be kept constant once the internal pressure reaches 0.1 MPa. The test sample is heated from room temperature (25°C) at a heating rate of 6°C / min until it reaches 150°C. The opening temperature of the test sample upon opening is defined as temperature A (°C).

[0024] (Measurement of seal strength A at opening temperature A determined in the opening test) An exterior material for energy storage devices with a total thickness of 153 μm is prepared, consisting of a base layer (PET (thickness 12 μm) / adhesive (thickness 3 μm) / nylon (thickness 15 μm)) / adhesive layer (thickness 3 μm) / barrier layer (aluminum alloy foil, thickness 40 μm) / adhesive layer (maleic anhydride modified polypropylene, thickness 40 μm) / heat-sealable resin layer (polypropylene, melting peak temperature 140°C, thickness 40 μm) laminated in this order, and cut to a size of 60 mm (width in the Z direction) x 150 mm (height in the X direction). The exterior material for energy storage devices is folded in half with the heat-sealable resin layer facing inward, and a resin film for energy storage devices (width in the Z direction 30 mm, height in the X direction 15 mm) is sandwiched in between. In this state, the laminate is obtained by heat sealing with a sealing machine with 7 mm wide upper and lower metal heads at 190°C x 0.5 MPa x 3 seconds. The resulting laminate is cut, and a 15mm strip-shaped test piece (with both sides of the adhesive film heat-sealed to the heat-sealable resin layer of the energy storage device's exterior material) is obtained from the center of the position where the resin film for the energy storage device is sandwiched between the heat-sealable resin layers of the energy storage device's exterior material. The seal strength of the obtained test piece is measured in accordance with the provisions of JIS K7127:1999, at temperatures A (opening temperature) and B (opening temperature -20°C), respectively, as follows: Using a tensile testing machine with a constant temperature chamber, one exterior material and the opposite exterior material are chucked at a speed of 300mm / min and pulled at a peeling angle of 180° (chuck distance is 50mm), and the seal strength (N / 15mm) at each temperature is measured.

[0025] (Laminated structure of resin film for energy storage devices) The resin film 1 for energy storage devices of this disclosure is composed of a laminate comprising at least a base film 11 and a pressure-sensitive adhesive layer 12, as shown, for example, in Figures 1 to 3.

[0026] The resin film 1 for energy storage devices may have a pressure-sensitive adhesive layer 12 laminated on only one side of the base film 11, as shown in Figures 1 to 3. Alternatively, although not shown, the pressure-sensitive adhesive layer 12 may be laminated on both sides of the base film 11. When the resin film 1 for energy storage devices is used in the application described in 2) below (as a heat-sealable resin layer for the exterior material of an energy storage device), it is preferable that the pressure-sensitive adhesive layer 12 is present on the outermost surface of the exterior material of the energy storage device, and that the pressure-sensitive adhesive layer 12 is not provided on the barrier layer side of the heat-sealable resin layer.

[0027] The resin film 1 for the energy storage device may have a two-layer structure in which a pressure-sensitive adhesive layer 12 is laminated on only one side of the base film 11, as shown in Figures 1 to 3, or it may have a three-layer structure in which a pressure-sensitive adhesive layer 12 is laminated on both sides of the base film 11, although this is not shown in the figures. Furthermore, layers different from the base film 11 and the pressure-sensitive adhesive layer 12 may be further laminated. It is preferable that the base film 11 and the pressure-sensitive adhesive layer 12 are in direct contact.

[0028] The thickness of the resin film 1 for energy storage devices is not particularly limited, as long as it does not exert the effects of the present invention. However, from the viewpoint of suitably exhibiting the effects of the present invention, it is preferably about 10 μm or more, more preferably about 15 μm or more, even more preferably about 20 μm or more, and also preferably about 200 μm or less, more preferably about 150 μm or less, even more preferably about 120 μm or less, and even more preferably about 100 μm or less. Preferred ranges include about 10 to 200 μm, about 10 to 150 μm, about 10 to 120 μm, about 10 to 100 μm, about 15 to 200 μm, about 15 to 150 μm, about 15 to 120 μm, about 15 to 100 μm, about 20 to 200 μm, about 20 to 150 μm, about 20 to 120 μm, and about 20 to 100 μm.

[0029] In the resin film 1 for energy storage devices, the ratio of the total thickness of the base film 11 and the pressure-sensitive adhesive layer 12 to the thickness (total thickness) of the laminate constituting the resin film 1 for energy storage devices is, for example, 50% or more, preferably 80% or more, more preferably 90% or more, more preferably 95% or more, even more preferably 98% or more, and may be 100%.

[0030] Furthermore, when the thickness of the base film 11 is set to 100%, the ratio of the thickness of the pressure-sensitive adhesive layer 12 is not particularly limited, as long as it does not produce the effects of the present invention. However, from the viewpoint of suitably exhibiting the effects of the present invention, it is preferably about 70% or less, more preferably about 60% or less, even more preferably about 50% or less, and also preferably about 3% or more, more preferably about 5% or more, even more preferably about 7% or more. Preferred ranges include approximately 3-70%, 3-60%, 3-50%, 5-70%, 5-60%, 5-50%, 7-70%, 7-60%, and 7-50%.

[0031] (Base film 11) In the resin film 1 for energy storage devices of this disclosure, the base film 11 functions as a support for a partially provided pressure-sensitive adhesive layer 12, and also functions to break when the internal temperature or pressure of the energy storage device rises, thereby allowing the energy storage device to be properly opened at the location of the resin film 1. The material forming the base film 11 can be any material capable of performing these functions, and can be formed using, for example, a resin. The resin may contain additives described later.

[0032] When the base film 11 is formed of a resin, the base film 11 can be formed of, for example, a resin film. The resin film may be an unstretched film or a stretched film. Examples of stretched films include uniaxially oriented films and biaxially oriented films, with biaxially oriented films being preferred. Examples of stretching methods for forming a biaxially oriented film include sequential biaxial stretching, inflation method, and simultaneous biaxial stretching.

[0033] Examples of resins that form the base film 11 include polyolefins, resins containing a polyolefin backbone such as acid-modified polyolefins, polyesters, and polyamides. The resin forming the base film 11 may also be a copolymer of these resins, or a modified version of the copolymer. Furthermore, it may be a mixture of these resins.

[0034] The base film 11 preferably contains these resins as its main component, and more preferably contains a resin containing a polyolefin skeleton as its main component. Here, "main component" means a resin component in which the content of the resin components contained in the base film 11 is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 99% by mass or more. For example, if the base film 11 contains polyester or polyamide as its main component, it means that the content of polyester or polyamide in the resin components contained in the base film 11 is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 99% by mass or more.

[0035] 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.

[0036] 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.

[0037] Furthermore, the polyolefin may be an acid-modified polyolefin. An acid-modified polyolefin is a polymer modified by block polymerization or graft polymerization of a polyolefin with an acid component. As the polyolefin to be acid-modified, the above-mentioned polyolefin, copolymers obtained by copolymerizing the above-mentioned polyolefin with polar molecules such as acrylic acid or methacrylic acid, or polymers such as cross-linked polyolefins can also be used. 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.

[0038] 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.

[0039] 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.

[0040] 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). Furthermore, the polyester may be a copolymer of two or more polyesters selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, and polyethylene isophthalate. These polyesters may be used individually or as mixtures of two or more.

[0041] 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.

[0042] The base film 11 may be a single layer or a multilayer of two or more layers. If the base film 11 is composed of two or more layers, the base film 11 may be a laminate formed by laminating resin films with an adhesive, or 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 film 11 in its unstretched state, or it may be used as the base film 11 after uniaxial stretching or biaxial stretching.

[0043] If the base film 11 is a laminate of two or more layers of resin film, the two or more layers of resin film may be laminated with an adhesive in between. Preferred adhesives include those similar to those exemplified in the adhesive layer 32 described later. The method for laminating the two or more layers of resin film 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 lamination is performed 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 before lamination. The anchor coat layer is similar to the adhesive exemplified in the adhesive layer 32 described later. In this case, the thickness of the anchor coat layer is, for example, about 0.01 to 1.0 μm.

[0044] Furthermore, at least one of the surface and interior of the base film 11 may contain additives such as lubricants, flame retardants, antiblocking agents, antioxidants, light stabilizers, tackifiers, antistatic agents, and colorants. Only one type of additive may be used, or two or more types may be mixed and used.

[0045] The thickness of the base film 11 is not particularly limited as long as the base film 11 performs the functions described above, but from the viewpoint of suitably exhibiting the effects of the present invention, it is preferably about 9 μm or more, more preferably about 10 μm or more, even more preferably about 20 μm or more, and also preferably about 146 μm or less, more preferably about 120 μm or less, even more preferably about 80 μm or less. Preferred ranges include about 9 to 146 μm, about 9 to 120 μm, about 9 to 80 μm, about 10 to 146 μm, about 10 to 120 μm, about 10 to 80 μm, about 20 to 146 μm, about 20 to 120 μm, and about 20 to 80 μm.

[0046] The base film 11 contains a coloring agent, which allows the resin film for energy storage devices to be colored. Known coloring agents such as pigments and dyes can be used. Furthermore, only one type of coloring agent may be used, or two or more types may be mixed and used.

[0047] The type of pigment is not particularly limited, as long as it does not impair the function of the base film 11 as a base material. 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.

[0048] Among colorants, carbon black is preferred for, for example, to give the appearance of resin films for energy storage devices a black color. Furthermore, from the viewpoint of dissipating heat generated from energy storage devices, mica is preferred.

[0049] The average particle size of the pigment is not particularly limited, but for example, it can be about 0.03 to 5 μm, preferably about 0.05 to 2 μm. The average particle size of the pigment is the median diameter measured by a laser diffraction / scattering particle size distribution analyzer.

[0050] The content of the coloring agent in the base film 11 is not particularly limited as long as the resin film for the energy storage device is colored, and for example, it can be about 5 to 60% by mass, preferably about 10 to 40% by mass.

[0051] (Resin layer) From the viewpoint of more favorably exhibiting the effects of the present invention, the resin film for energy storage devices preferably includes at least one resin layer having a melting peak temperature of 80°C or higher and 240°C or lower. The melting peak temperature is more preferably 90°C or higher, more preferably 200°C or lower, and even more preferably 160°C or lower. Preferred ranges include approximately 80-240°C, 80-200°C, 80-160°C, 90-240°C, 90-200°C, and 90-160°C.

[0052] Furthermore, from the viewpoint of more favorably exhibiting the effects of the present invention, in the applications described in 1), 2), or 3) below, it is preferable that the resin film for energy storage devices of the present disclosure includes at least one resin layer having a lower melting peak temperature than the heat-sealable resin layer of the exterior material for energy storage devices. In the present disclosure, the melting peak temperature refers to the temperature at the endothermic peak of the DSC curve obtained by differential scanning calorimetry.

[0053] The resin layer described above may be the base film 11 or a different material from the base film 11, but is preferably the base film 11. If the resin layer is different from the base film 11, the resin film for energy storage devices of this disclosure further comprises the resin layer in addition to the base film 11 and the pressure-sensitive adhesive layer 12.

[0054] (Pressure-sensitive adhesive layer 12) In the resin film 1 for energy storage devices of this disclosure, the pressure-sensitive adhesive layer 12 constitutes at least one surface of the resin film 1 for energy storage devices and is partially provided on the base film 11. The pressure-sensitive adhesive layer 12 is a layer that performs a function (temporary fixing function) of fixing the resin film 1 for energy storage devices by pressure-sensitive adhesive force at the position where the resin film 1 for energy storage devices is placed on the energy storage device 10 during the manufacturing of the energy storage device 10. By fixing the resin film 1 for energy storage devices in a predetermined position during the manufacturing of the energy storage device 10, displacement of the resin film 1 for energy storage devices during the manufacturing of the energy storage device 10 is suppressed, and the resin film 1 for energy storage devices can be placed with high positional accuracy.

[0055] From the viewpoint of suitably exhibiting the effects of the present invention, the ratio of the area of ​​the portion on which the pressure-sensitive adhesive layer is laminated to the area of ​​one side of the base film is preferably about 50% or less, more preferably about 40% or less, even more preferably about 30% or less, and also preferably about 5% or more, more preferably about 10% or more, even more preferably about 15% or more. Preferred ranges include about 5-50%, about 5-40%, about 5-30%, about 10-50%, about 10-40%, and about 10-30%.

[0056] The position on the base film 11 where the pressure-sensitive adhesive layer 12 is provided is not particularly limited, as long as the pressure-sensitive adhesive layer 12 performs its function. For example, as shown in Figure 4, the pressure-sensitive adhesive layer 12 can be provided at one end of the base film 11.

[0057] Furthermore, as shown in Figures 2, 3, and 5, for example, the pressure-sensitive adhesive layer 12 may also be provided in a pattern on the base film 11. Figures 2, 3, and 5 show an example in which the pressure-sensitive adhesive layer 12 is provided in a dot pattern on the base film 11. The pattern on which the pressure-sensitive adhesive layer 12 is formed is not particularly limited and can include dots, stripes, grids, geometric patterns (polygons such as triangles, squares, and rectangles, as well as circles, ellipses, etc.).

[0058] After the resin film 1 is placed during the manufacturing process of the energy storage device, at least a portion of the area on the resin film 1 where the pressure-sensitive adhesive layer 12 is formed can be removed. When removing the area on the resin film 1 where the pressure-sensitive adhesive layer 12 is formed from the resin film 1 applied to the energy storage device 10, for example, if the resin film 1 has the pressure-sensitive adhesive layer 12 provided at one end of the base film 11, as shown in Figure 4, the pressure-sensitive adhesive layer 12 can be removed by cutting in the thickness direction at the location where the pressure-sensitive adhesive layer 12 is formed. After the resin film 1 is applied to the energy storage device 10, the portion on which the pressure-sensitive adhesive layer 12 is formed may be removed entirely or partially.

[0059] Furthermore, when the resin film 1 is applied to the energy storage device 10 and the resin film 1 is heat-fused to the heat-fusible resin layer 35, etc., a difference in adhesive strength between the resin film 1 and the heat-fusible resin layer 35, etc. may occur between the locations where the pressure-sensitive adhesive layer 12 is present and the locations where it is not. In such cases, the design can be made so that no difference in adhesive strength occurs by not placing the pressure-sensitive adhesive layer 12 in the locations where the resin film 1 and the heat-fusible resin layer 35, etc. are heat-fused. Alternatively, as described above, the design can be made so that no difference in adhesive strength occurs by removing all portions where the pressure-sensitive adhesive layer 12 is formed.

[0060] Furthermore, the pressure-sensitive adhesive layer 12 only needs to constitute the surface of at least one side of the resin film 1 and be partially formed on the base film 11 (i.e., the pressure-sensitive adhesive layer 12 only needs to perform a temporary fixing function). For example, as shown in Figure 2, the entire pressure-sensitive adhesive layer 12 may be located on the base film 11, or at least a part of the pressure-sensitive adhesive layer 12 may be embedded in the base film 11, as shown in Figure 3.

[0061] The material used to form the pressure-sensitive adhesive layer 12 is not particularly limited, as long as it has pressure-sensitive adhesive properties (tackiness) and can perform the aforementioned functions of the pressure-sensitive adhesive layer 12. Examples of materials used to form the pressure-sensitive adhesive layer 12 include resin compositions containing a resin and an adhesive component.

[0062] Examples of resins used in such resin compositions include resins containing a polyolefin skeleton, such as polyolefins and acid-modified polyolefins.

[0063] Examples of resins containing a polyolefin backbone, such as polyolefins and acid-modified polyolefins, include the same resins exemplified in the (base film 11) section above.

[0064] Examples of adhesive components include rosin or its derivatives, such as rosin, hydrogenated rosin, polymerized rosin, and rosin esters; terpene resins such as α-pinene, β-pinene, and limonene; terpene phenol resins, coumarone-indene resins, styrene resins, xylene resins, phenol resins, petroleum resins, and hydrogenated petroleum resins. Furthermore, hydrogenated terpene resins, rosin resins, and petroleum resins are compatible with the elastomer phase of styrene block copolymers and are highly effective in improving adhesion to non-polar materials such as polyolefins, while xylene resins, phenol resins, and styrene resins are compatible with the styrene phase and have the effect of increasing cohesive force. For this reason, hydrogenated terpene resins, rosin resins, and petroleum resins can also be combined with xylene resins, phenol resins, and styrene resins to create adhesive components.

[0065] Furthermore, amorphous polyolefins can also be used as adhesive components. Examples of amorphous polyolefins include amorphous polypropylene, or copolymers of amorphous propylene with other α-olefins. Specific examples include propylene-ethylene copolymer, propylene-butene-1 copolymer, propylene-butene-1-ethylene terpolymer, propylene-hexene-1-octene-1-terpolymer, propylene-hexene-1-4-methylpentene-1-terpolymer, propylene-hexene-1-4-methylpentene-1-terpolymer, and polybutene-1. Among the target amorphous alpha polyolefins, those with a high content of low molecular weight components, a number average molecular weight of 20,000 or less, and a glass transition temperature of -20°C or lower are preferred.

[0066] Amorphous polyolefin is preferred as the adhesive component. Examples of commercially available amorphous polyolefins include REXtac2280 (manufactured by REXtac LLC). In the pressure-sensitive adhesive layer 12, for example, when REXtac2280 is used as the adhesive component and modified polyolefin is used as the resin, the content of REXtac2280 is preferably about 10 parts by mass or about 20 parts by mass per 100 parts by mass of modified polyolefin.

[0067] Other examples of adhesive components include elastomers.

[0068] The elastomer is not particularly limited as long as it is compounded with a resin and exhibits pressure-sensitive adhesion. For example, an elastomer composed of a thermoplastic resin (thermoplastic elastomer) is preferred.

[0069] Preferred elastomers include styrene-based elastomers, olefin-based elastomers, acrylic-based elastomers, silicone-based elastomers, urethane-based elastomers, polyester-based elastomers, polyamide-based elastomers, and rubber-based elastomers. The elastomer may be used individually or in combination of two or more types.

[0070] There are no particular limitations on the type of styrene-based elastomer, but specific examples include styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, styrene-ethylene-butylene-styrene block copolymer, and styrene-ethylene-propylene-styrene block copolymer.

[0071] Examples of olefin-based elastomers include copolymers of α-olefins having 2 to 20 carbon atoms, such as ethylene, propylene, 1-butene, 1-hexene, and 4-methyl-1-pentene. For example, ethylene-propylene copolymer (EPR) and ethylene-propylene-diene copolymer (EPDM) are preferred. Also, copolymers of α-olefins with non-conjugated dienes having 2 to 20 carbon atoms, such as dicyclopentadiene, 1,4-hexadiene, cyclooctadiene, methylenenorbornene, ethylidenenorbornene, butadiene, and isoprene are also examples. Furthermore, carboxylated nitrile rubber obtained by copolymerizing butadiene-acrylonitrile copolymer with methacrylic acid is also an example.

[0072] Acrylic elastomers are mainly composed of acrylic acid esters, and specifically, ethyl acrylate, butyl acrylate, methoxyethyl acrylate, ethoxyethyl acrylate, etc., are preferably used. In addition, glycidyl methacrylate, allyl glycidyl ether, etc., can be used as crosslinking monomers. Furthermore, copolymers with acrylonitrile or ethylene can also be used. Specifically, examples include acrylonitrile-butyl acrylate copolymer, acrylonitrile-butyl acrylate-ethyl acrylate copolymer, and acrylonitrile-butyl acrylate-glycidyl methacrylate copolymer.

[0073] Silicone-based elastomers primarily consist of organopolysiloxanes, and include polydimethylsiloxane-based, polymethylphenylsiloxane-based, and polydiphenylsiloxane-based elastomers.

[0074] Urethane elastomers consist of structural units of a hard segment made of low molecular weight ethylene glycol and diisocyanate, and a soft segment made of high molecular weight (long-chain) diol and diisocyanate. Examples of high molecular weight (long-chain) diols include polypropylene glycol, polytetramethylene oxide, poly(1,4-butylene adipate), poly(ethylene-1,4-butylene adipate), polycaprolactone, poly(1,6-hexylene carbonate), and poly(1,6-hexylene neopentylene adipate).

[0075] Polyester elastomers are obtained by polycondensation of a dicarboxylic acid or its derivative with a diol compound or its derivative. Specific examples of dicarboxylic acids include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, and naphthalenedicarboxylic acid, as well as aromatic dicarboxylic acids in which the hydrogen atoms of the aromatic kernel are substituted with methyl, ethyl, or phenyl groups, aliphatic dicarboxylic acids having 2 to 20 carbon atoms such as adipic acid, sebacic acid, and dodecanedicarboxylic acid, and alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid. These compounds can be used individually or in combination of two or more.

[0076] Specific examples of diol compounds include aliphatic and alicyclic diols such as ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 1,10-decanediol, and 1,4-cyclohexanediol. Furthermore, examples include bisphenol A, bis-(4-hydroxyphenyl)-methane, bis-(4-hydroxy-3-methylphenyl)-propane, and resorcinol. These compounds can be used individually or in combination of two or more.

[0077] Examples of polyamide-based elastomers include block copolymers in which polyamide is the hard segment component and polybutadiene, butadiene-acrylonitrile copolymer, styrene-butadiene copolymer, polyisoprene, ethylene-propylene copolymer, polyether, polyester, polybutadiene, polycarbonate, polyacrylate, polymethacrylate, polyurethane, or silicone rubber are the soft segment components.

[0078] Examples of rubber-based elastomers include polyisobutylene.

[0079] Among elastomers, styrene-based elastomers and olefin-based elastomers are preferred, with styrene-based elastomers being particularly preferred.

[0080] The content of the adhesive component in the pressure-sensitive adhesive layer 12 is not particularly limited as long as the pressure-sensitive adhesive layer 12 can perform the functions described above, but for example it is about 0.5% by mass or more, preferably about 1.5% by mass or more, more preferably about 3% by mass or more, and also for example it is about 80% by mass or less, preferably about 50% by mass or less, more preferably about 20% by mass or less, and preferred ranges include about 0.5 to 80% by mass, about 0.5 to 50% by mass, about 0.5 to 20% by mass, about 1.5 to 80% by mass, about 1.5 to 50% by mass, about 1.5 to 20% by mass, about 3 to 80% by mass, about 3 to 50% by mass, and about 3 to 20% by mass.

[0081] The adhesive component may be used alone or in combination of two or more types.

[0082] Furthermore, the pressure-sensitive adhesive layer 12 can also be formed from adhesive materials such as polyurethane, polyester, polyamide, acrylic, polyvinyl acetal, polycarbonate, polyethylene, polyacrylic acid, and polymethyl methacrylate, as well as tacky materials such as phenolic resin, urea resin, and silicone resin.

[0083] The thickness of the pressure-sensitive adhesive layer 12 is not particularly limited as long as the pressure-sensitive adhesive layer 12 performs the functions described above. However, from the viewpoint of suitably exhibiting the effects of the present invention, it is preferably about 0.5 μm or more, more preferably about 1 μm or more, even more preferably about 1.5 μm or more, and also preferably about 40 μm or less, more preferably about 20 μm or less, and even more preferably about 10 μm or less. Preferred ranges include about 0.5 to 40 μm, about 0.5 to 20 μm, about 0.5 to 10 μm, about 1 to 40 μm, about 1 to 20 μm, about 1 to 10 μm, about 1.5 to 40 μm, about 1.5 to 20 μm, and about 1.5 to 10 μm.

[0084] [Application] The resin film 1 of this disclosure can be fixed with high positional accuracy during the manufacturing of energy storage devices, and therefore can be suitably used as a resin film for energy storage devices. Specific applications of the resin film 1 for energy storage devices of this disclosure include the following 1) to 4).

[0085] 1) Applications in which the heat-sealable resin layers of the exterior material for energy storage devices are interposed between the heat-sealable resin layers at the location where they are heat-sealed together. 2) Applications as a heat-sealable resin layer for exterior materials of energy storage devices 3) Applications in which the exterior of an energy storage device includes an exterior material for the energy storage device and a lid, and is used so as to be interposed between the exterior material for the energy storage device and the lid. 4) The casing of the energy storage device includes an casing material for the energy storage device and a cover. The lid comprises a lid body and a covering that covers the periphery of the lid body. Applications in which it is interposed between the lid body and the covering

[0086] The following will explain the uses described in 1) through 4) above with specific examples.

[0087] 1) Uses (Applications in which the heat-sealable resin layers of the exterior material for energy storage devices are interposed between the heat-sealable resin layers at the point where they are heat-sealed together.) For example, in Figures 7 to 9, the resin film 1 of this disclosure is interposed between opposing heat-sealable resin layers 35 at the peripheral edge 3a of the exterior material 3 for the energy storage device, where the heat-sealable resin layers 35 are heat-sealed to each other to seal the energy storage device element 4 of the energy storage device 10 of this disclosure. The resin film 1 and the heat-sealable resin layers 35 on both sides thereof are heat-sealed when the energy storage device element 4 is sealed with the exterior material 3 for the energy storage device. That is, both sides of the resin film 1 are heat-sealable to the heat-sealable resin layers 35.

[0088] The resin film 1 of this disclosure seals the energy storage device 10 until the energy storage device 10 reaches a high temperature (for example, around 100°C to 130°C), and when the energy storage device reaches that high temperature (for example, around 100°C to 130°C), the energy storage device opens at the position of the resin film 1 between the heat-sealable resin layers, allowing gas generated inside the energy storage device to be released to the outside. By placing the resin film 1 in a part of the position where the heat-sealable resin layers 35 of the exterior material for the energy storage device are heat-sealed together, gas can be selectively discharged to the outside from a specific position where the resin film 1 is placed. In other words, the position from which the gas is discharged can be set to any position in the heat-sealed portion between the heat-sealable resin layers 35.

[0089] In the application of 1) described above, the position in which the resin film 1 of this disclosure is placed is not particularly limited as long as it is a position in which the heat-sealable resin layers 35 of the exterior material 3 for the energy storage device are heat-sealed together. For example, if the energy storage device 10 is rectangular in plan view, the resin film 1 can be placed on either the long side or the short side of the peripheral edge 3a of the heat-sealed exterior material 3 for the energy storage device. Furthermore, the resin film 1 of this disclosure only needs to be placed in at least one location among the positions in which the heat-sealable resin layers 35 of the exterior material 3 for the energy storage device are heat-sealed together, and may be placed in two or more locations.

[0090] The size of the resin film 1 is not particularly limited, as long as gas is properly released when opened. For example, as shown in Figure 7, if the energy storage device 10 is rectangular in plan view and the resin film is placed along one side of the rectangle (in the example in Figure 7, the resin film is placed along the z direction), the ratio of the length of the resin film to the length of that side is, for example, about 3 to 98%. Also, the ratio of the width direction of the resin film (perpendicular to the length direction and thickness direction, in the example in Figure 7, the direction along the x direction) to the seal width of that side (perpendicular to the length direction and thickness direction, in the example in Figure 7, the direction along the x direction) is, for example, about 30 to 200%. Furthermore, the size of the resin film in the width direction is, for example, about 20 to 300%, with the size of the resin film 1 in the length direction as the base 100%.

[0091] In the energy storage device 10, the metal terminal 2 is electrically connected to the energy storage device element 4 and protrudes to the outside of the energy storage device exterior material 3. It is preferable that the resin film 1 of this disclosure is positioned so as not to be located between the metal terminal 2 and the energy storage device exterior material 3 (heat-fusible resin layer). Furthermore, it is preferable that the resin film 1 of this disclosure does not come into contact with the metal terminal 2.

[0092] 2) Uses (Used as a heat-sealable resin layer for exterior materials of energy storage devices) In applications where the resin film 1 for energy storage devices of this disclosure is used as a heat-sealable resin layer 35 of an exterior material 3 for energy storage devices, as shown in Figure 6, the resin film 1 for energy storage devices of this disclosure is used as a heat-sealable resin layer 35 of an exterior material 3 for energy storage devices which is composed of a laminate having at least a barrier layer 33 and a heat-sealable resin layer 35 in that order from the outside.

[0093] By using the resin film 1 for energy storage devices of this disclosure as the heat-sealable resin layer 35 of the exterior material 3 for energy storage devices, the energy storage device can be opened at the location of the heat-sealable resin layer 35, allowing gas generated inside the energy storage device to be released to the outside. In this application, when multiple exterior materials for energy storage devices are used to seal the energy storage device elements, it is sufficient that the heat-sealable resin layer of at least one of the exterior materials for energy storage devices is made of the resin film 1 for energy storage devices of this disclosure, and the heat-sealable resin layers of the remaining exterior materials for energy storage devices do not need to be made of the resin film 1 for energy storage devices.

[0094] In application 2), since the resin film 1 for energy storage devices is used as the heat-sealable resin layer 35 of the exterior material 3 for energy storage devices, when sealing the energy storage device elements with the exterior material 3 for energy storage devices, the pressure-sensitive adhesive layer 12 located on the surface of the heat-sealable resin layer 35 can fix (temporarily fix) the position where the heat-sealable resin layers 35 are sealed together. Therefore, the positional accuracy when heat-sealing the heat-sealable resin layers 35 together can be improved.

[0095] 3) Uses (Applications in which the exterior of a power storage device includes an exterior material for the power storage device and a lid, and is used interposed between the exterior material for the power storage device and the lid.) As shown in Figures 9 and 10, if the exterior 30 of the energy storage device 10 includes an exterior material 3 for the energy storage device and a cover 60, the resin film 1 for the energy storage device of this disclosure can be used interposed between the exterior material 3 and the cover 60. Figure 9 shows two resin films 1: one used for application 1) and another used for application 3).

[0096] As shown in Figures 9 and 10, in this disclosure, the energy storage device element 4 of the energy storage device 10 may be sealed by other members such as a lid 60 in addition to the energy storage device exterior material 3. The energy storage device exterior material 3 and other members such as the lid 60 constitute an exterior body 30 (exterior body for the energy storage device) that seals the energy storage device element 4. As shown in Figures 9 and 10, for example, the energy storage device element may be housed inside the cylindrically configured energy storage device exterior material 3, and the opening may be closed with a lid 60. Figure 10 shows a diagram in which the lid 60 is composed of a lid body 62 and a covering 61 (covering the periphery of the lid body 62).

[0097] Another example of using the cover 60 is to house the energy storage device elements connected to the cover 60 inside the casing material 3 for the energy storage device, which is configured in a cylindrical shape so that an opening is formed, and then close the opening with the cover 60. In this case, the cover 60 also functions as a metal terminal 2 (for example, as shown in Figure 12). It is preferable that the cover 60 and the casing material 3 for the energy storage device are joined by any means.

[0098] When using the cover 60, it is preferable that the exterior material 3 for the energy storage device be wrapped around the energy storage device element and the cover 60, in order to reduce the dead space between the energy storage device element and the exterior material 3 for the energy storage device in order to improve the volumetric energy density of the energy storage device.

[0099] The lid 60 can be formed, for example, from a resin molded product, a metal molded product, or a combination thereof. In this disclosure, when the lid is described as a resin molded product, the lid is not composed solely of a film as defined by JIS K6900-1994 [Plastics - Terminology]. When the lid is a metal molded product, the lid can also function as a metal terminal, and therefore the lid can be a metal terminal. The lid may be composed of a resin material and a conductive material.

[0100] For example, in the schematic diagrams shown in Figures 9 and 10, an energy storage device element is housed inside a cylindrical outer casing material 3 for the energy storage device, and the opening is closed by a resin lid 60. The lid 60 also has a through hole into which a metal terminal 2 electrically connected to the energy storage device element 4 is inserted. In this embodiment, the energy storage device 10 consists of an outer casing material 3 and a lid 60 that seals the energy storage device element 4, and the metal terminal 2 is exposed to the outside through the through hole in the lid 60. An adhesive film 5 can be placed between the metal terminal 2 and the lid 60 to improve their adhesion.

[0101] In the application of 3) described herein, by using the resin film 1 for energy storage devices of this disclosure interposed between the exterior material 3 for energy storage devices and the lid 60, the energy storage device can be opened at the position between the exterior material 3 and the lid 60, and gas generated inside the energy storage device can be released to the outside.

[0102] In the application of 3) described above, the position in which the resin film 1 of the present disclosure is placed is not particularly limited as long as it is between the exterior material 3 for the energy storage device and the lid 60. For example, if the lid 60 is rectangular in plan view, the resin film 1 can be placed on either the long side or the short side of the periphery of the lid 60. Furthermore, the resin film 1 of the present disclosure only needs to be placed in at least one location between the exterior material 3 for the energy storage device and the lid 60, and may be placed in two or more locations.

[0103] The size of the resin film 1 is not particularly limited, as long as gas is properly released when opened. For example, as shown in Figure 10, if the lid 60 is rectangular in plan view and the resin film 1 is placed along one side of the rectangle, the ratio of the length of the resin film to the length of that side is, for example, about 3 to 98%. Furthermore, the size of the resin film 1 in the width direction (the direction perpendicular to the length direction and thickness direction, and in the example of Figure 10, the depth direction of the paper) is, for example, about 20 to 300% of the size of the resin film 1 in the length direction, with the length direction being 100% as the base.

[0104] 4) Uses (An application in which an outer casing of an energy storage device includes an outer casing material for an energy storage device and a lid, the lid includes a lid body and a covering that covers the periphery of the lid body, and is used interposed between the lid body and the covering.) As shown in Figures 11 and 12, the resin film for the energy storage device of this disclosure can also be used interposed between the lid body 62 and the covering 61 that constitute the lid 60 described above.

[0105] In other words, as explained in the application of 3) above, in this disclosure, the energy storage device element 4 of the energy storage device 10 may be sealed by other members such as a lid 60 in addition to the energy storage device exterior material 3. The energy storage device exterior material 3 and other members such as the lid 60 constitute an exterior body 30 (exterior body for energy storage device) that seals the energy storage device element 4. As shown in Figures 11 and 12, for example, the energy storage device element may be housed inside the cylindrical energy storage device exterior material 3, and the opening may be closed with a lid 60. In Figures 11 and 12 relating to the application of 4), the lid 60 is shown to be composed of a lid body 62 and a covering 61 that covers the periphery of the lid body 62.

[0106] As described above, the lid 60 can be formed, for example, from a resin molded product, a metal molded product, or a combination thereof. In this disclosure, when the lid is described as a resin molded product, the lid is not composed solely of a film as defined by JIS K6900-1994 [Plastics - Terminology]. When the lid is a metal molded product, the lid can also function as a metal terminal, and therefore the lid can be a metal terminal. The lid may be composed of a resin material and a conductive material.

[0107] For example, in the schematic diagram shown in Figure 11, an energy storage device element is housed inside a cylindrical outer casing material 3 for the energy storage device, and the opening is closed by a resin lid 60. The lid body 62 also has a through hole into which a metal terminal 2 electrically connected to the energy storage device element 4 is inserted. In this embodiment, the energy storage device 10 consists of an outer casing material 3 and a lid 60 that seals the energy storage device element 4, and the metal terminal 2 is exposed to the outside through the through hole in the lid body 62. An adhesive film 5 can be placed between the metal terminal 2 and the lid body 62 to improve their adhesion.

[0108] Furthermore, in Figure 12, the energy storage device element, connected to the lid body 62, is housed inside the cylindrical exterior material 3 for the energy storage device, which is configured to form an opening, and the opening is closed by the lid 60. The lid body 62 also functions as a metal terminal 2. It is preferable that the lid 60 and the exterior material 3 for the energy storage device are joined by any means.

[0109] As described above, in order to improve the volumetric energy density of the energy storage device, it is preferable that the energy storage device exterior material 3 be wrapped around the energy storage device element and the cover 60 in order to reduce the dead space between the energy storage device element and the energy storage device exterior material 3.

[0110] In the application of 4), by using the resin film 1 for energy storage devices of this disclosure interposed between the lid body 62 and the covering 61, the energy storage device can be opened at a position between the lid body 62 and the covering 61 (i.e., at the position of the lid 60), and gas generated inside the energy storage device can be released to the outside.

[0111] In the application of 4) described above, the position in which the resin film 1 of the present disclosure is placed is not particularly limited as long as it is between the lid body 62 and the covering 61. For example, if the lid body 62 is rectangular in plan view, the resin film 1 can be placed on either the long side or the short side of the periphery of the lid body 62. Furthermore, the resin film 1 of the present disclosure only needs to be placed in at least one location between the lid body 62 and the covering 61, and may be placed in two or more locations.

[0112] The size of the resin film 1 is not particularly limited, as long as gas is properly released when opened. For example, as shown in Figures 11 and 12, if the lid body 62 is rectangular in plan view and the resin film is placed along one side of the rectangle, the ratio of the length of the resin film to the length of that side is, for example, about 3 to 98%. Also, the size of the resin film in the width direction (the direction perpendicular to the length direction and thickness direction, and in the example of Figures 11 and 12, the depth direction of the paper) is, for example, about 20 to 300%, with the size of the resin film 1 in the length direction as the base 100%.

[0113] [Energy storage devices] As described above, the energy storage device 10 of this disclosure has a structure in which the energy storage device element 4 is sealed in an outer casing 30. The energy storage device element 4 comprises at least a positive electrode, a negative electrode, and an electrolyte. In the energy storage device 10 of this disclosure, the resin film 1 is included in at least one of the following embodiments, for example: 1) to 4).

[0114] 1) An embodiment in which the heat-fusible resin layers of the exterior material for an energy storage device are interposed between the heat-fusible resin layers at the position where they are heat-fussed together. 2) Embodiments included as a heat-fusible resin layer for exterior material of energy storage device 3) The exterior of the energy storage device includes an exterior material for the energy storage device and a cover. A component included so as to be interposed between the exterior material for the energy storage device and the lid. 4) The casing of the energy storage device includes an casing material for the energy storage device and a cover. The lid comprises a lid body and a covering that covers the periphery of the lid body. an embodiment that is interposed between the lid body and the covering.

[0115] These embodiments 1) to 4) correspond to embodiments in which the resin film 1 of the present disclosure is applied to the energy storage device 10 for the uses described in 1) to 4) above.

[0116] Each of these energy storage devices according to 1) to 4) can be manufactured by employing at least one of the following processes 1) to 4).

[0117] In step 1), the resin film 1 is positioned between the heat-sealable resin layers 35 of the exterior material 3 for the energy storage device at the location where the heat-sealable resin layers 35 of the exterior material 3 for the energy storage device are heat-sealed together. After fixing the pressure-sensitive adhesive layer 12 of the resin film 1 to the surface of the heat-fusible resin layer 35, the heat-fusible resin layers 35 are heat-fused together with the resin film 1 in between. By employing step 1), the energy storage device 10 according to the embodiment of 1) is manufactured.

[0118] Furthermore, in step 2), the resin film 1 is used as the heat-sealable resin layer 35 of the exterior material 3 for the energy storage device. The pressure-sensitive adhesive layer 12 present on the surface of one side of the heat-fusible resin layer 35 of the exterior material 3 for the energy storage device is fixed to the surface of the heat-fusible resin layer 35 of the other side of the exterior material 3 for the energy storage device, and then the heat-fusible resin layers 35 are heat-fused together. By employing step 2), an energy storage device 10 according to the embodiment of 2) is manufactured.

[0119] Furthermore, in step 3), the outer casing 30 of the energy storage device 10 includes the outer casing material 3 for the energy storage device and the lid 60. After fixing the pressure-sensitive adhesive layer 12 of the resin film 1 to the exterior material 3 or lid 60 for the energy storage device, the exterior material 3 and lid 60 for the energy storage device are heat-fused together with the resin film 1 in between. By employing step 3), an energy storage device 10 according to the embodiment of 3) is manufactured.

[0120] Furthermore, in step 4), the outer casing 30 of the energy storage device 10 includes the outer casing material 3 for the energy storage device and the lid 60. The lid 60 includes a lid body 62 and a covering 61 that covers the periphery of the lid body 62. After fixing the resin film 1 to the lid body 62 or the covering 61, the lid body 62 and the covering 61 are heat-fused together with the resin film 1 in between. By employing step 4), the energy storage device 10 according to the embodiment of 4) is manufactured.

[0121] Furthermore, steps 1) and 2) may further include a step of removing at least a portion of the area on the resin film 1 where the pressure-sensitive adhesive layer 12 is formed. As described above, when removing the area on which the pressure-sensitive adhesive layer 12 is formed from the resin film 1 applied to the energy storage device 10, for example, if the resin film 1 has the pressure-sensitive adhesive layer 12 provided at one end of the base film 11, as shown in Figure 4, the pressure-sensitive adhesive layer 12 can be removed by cutting in the thickness direction at the location where the pressure-sensitive adhesive layer 12 is formed. After the resin film 1 is applied to the energy storage device 10, the area on which the pressure-sensitive adhesive layer 12 is formed may be completely removed or partially removed.

[0122] Furthermore, as described above, when the resin film 1 is applied to the energy storage device 10 and the resin film 1 is heat-fused to the heat-sealable resin layer 35, etc., a difference in adhesive strength between the resin film 1 and the heat-sealable resin layer 35, etc. may occur in areas where the pressure-sensitive adhesive layer 12 is present and areas where it is not. In such cases, however, the design can be made so that no difference in adhesive strength occurs by removing all of the areas where the pressure-sensitive adhesive layer 12 is formed.

[0123] [Exterior material for energy storage devices 3] An example of an exterior material 3 for an energy storage device is one having a laminated structure consisting of a laminate having at least a barrier layer 33 and a heat-fusible resin layer 35 in that order. Figure 6 shows an example of the cross-sectional structure of the exterior material 3 for an energy storage device, in which a base layer 31 (provided as needed), an adhesive layer 32 (provided as needed), a barrier layer 33, an adhesive layer 34 (provided as needed), and a heat-fusible resin layer 35 are laminated in that order. In the exterior material 3 for an energy storage device, the barrier layer 33 is on the outer layer side, and the heat-fusible resin layer 35 is the innermost layer. When assembling the energy storage device, the heat-fusible resin layers 35 located around the periphery of the energy storage device element 4 are brought into contact with each other and heat-fused to seal the energy storage device element 4, thereby sealing the energy storage device element 4. Figures 7 and 8 show an energy storage device 10 using an embossed type exterior material 3 for an energy storage device formed by embossing, but the exterior material 3 for an energy storage device may be an unformed pouch type. Note that pouch-type packaging includes three-sided seal, four-sided seal, and pillow-type packaging, but any type is acceptable.

[0124] The thickness of the laminate constituting the exterior material 3 for energy storage devices is not particularly limited, but from the viewpoint of cost reduction and improvement of energy density, for example, it can be about 300 μm or less, preferably about 250 μm or less, about 210 μm or less, about 190 μm or less, 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 3 for energy storage devices can be preferably about 35 μm or more, about 45 μm or more, about 60 μm or more, about 155 μm or more, or about 190 μm or more. Furthermore, the preferred range for the laminate constituting the outer casing material 3 for the energy storage device is, for example, approximately 35-300 μm, approximately 35-250 μm, approximately 35-210 μm, approximately 35-190 μm, approximately 35-180 μm, approximately 35-155 μm, approximately 35-120 μm, approximately 45-300 μm, approximately 45-250 μm, approximately 45-210 μm, approximately 45-190 μm, approximately 45-180 μm, approximately 45-155 μm, approximately 45-120 μm, approximately 60-300 μm, approximately 60-250 μm, and 60- Examples of thicknesses include approximately 210 μm, 60-190 μm, 60-180 μm, 60-155 μm, 60-120 μm, 155-300 μm, 155-250 μm, 155-210 μm, 155-190 μm, 155-180 μm, 190-300 μm, 190-250 μm, and 190-210 μm. In particular, when creating lightweight thin films for energy storage devices, approximately 60-155 μm is preferred, and when improving moldability, approximately 155-190 μm is preferred.

[0125] Furthermore, the energy storage device exterior material 3 can be suitably applied to all-solid-state batteries. The thickness of the laminate constituting the all-solid-state battery exterior material is not particularly limited, but from the viewpoint of cost reduction and energy density improvement, it is preferably about 10,000 μm or less, about 8,000 μm or less, or about 5,000 μm or less. From the viewpoint of maintaining the function of the all-solid-state battery exterior material, which is to protect the battery elements, it is preferably about 100 μm or more. Examples of preferred ranges include approximately 150 μm or more and approximately 200 μm or more, and examples of preferred ranges include approximately 100 to 10000 μm, approximately 100 to 8000 μm, approximately 100 to 5000 μm, approximately 150 to 10000 μm, approximately 150 to 8000 μm, approximately 150 to 5000 μm, approximately 200 to 10000 μm, approximately 200 to 8000 μm, and approximately 200 to 5000 μm, with approximately 100 to 5000 μm being particularly preferred.

[0126] (Base material layer 31) In the exterior material 3 for the energy storage device, the base layer 31 is a layer that functions as the base material for the exterior material of the energy storage device and is the layer that forms the outermost layer.

[0127] The material forming the base layer 31 is not particularly limited, as long as it possesses insulating properties. Examples of materials for forming the base layer 31 include polyester, polyamide, epoxy, acrylic, fluororesin, polyurethane, silicon resin, phenol, polyetherimide, polyimide, and mixtures or copolymers thereof. Polyesters such as polyethylene terephthalate have excellent electrolyte resistance and are less prone to whitening when exposed to electrolyte, making them suitable for use as a material for forming the base layer 31. Polyamide films also have excellent stretchability, which can prevent whitening due to resin cracking of the base layer 31 during molding, making them suitable for use as a material for forming the base layer 31.

[0128] The base layer 31 may be formed from a uniaxially or biaxially stretched resin film, or from an unstretched resin film. Among these, uniaxially or biaxially stretched resin films, and especially biaxially stretched resin films, are suitable for use as the base layer 31 because their heat resistance is improved by oriented crystallization.

[0129] Among these, nylon, polyester, and more preferably biaxially oriented nylon and biaxially oriented polyester are used as the resin film forming the base layer 31. Furthermore, since all-solid-state batteries are often sealed at high temperatures of 200°C or higher to achieve a service temperature of 150°C or higher, biaxially oriented polyester is the most suitable.

[0130] The base layer 31 can also be constructed by laminating resin films of different materials to improve pinhole resistance and insulation when used as packaging for energy storage devices. Specifically, examples include a multilayer structure in which polyester film and nylon film are laminated, or a multilayer structure in which biaxially oriented polyester and biaxially oriented nylon are laminated. When the base layer 31 is a multilayer structure, each resin film may be bonded via an adhesive, or it may be laminated directly without an adhesive. When bonding without an adhesive, examples include bonding in a thermally molten state such as co-extrusion, sand lamination, or thermal lamination. For the above high-temperature sealing, it is desirable that at least the outermost layer be biaxially oriented polyester.

[0131] Furthermore, the base layer 31 may be made friction-reducing to improve moldability. When the base layer 31 is made friction-reducing, there are no particular restrictions on the coefficient of friction of its surface, but for example, it may be 1.0 or less. Examples of methods for making the base layer 31 friction-reducing include mat treatment, formation of a thin film layer of a slip agent, and combinations thereof.

[0132] The thickness of the substrate layer 31 can be, for example, about 10 to 50 μm, preferably about 15 to 30 μm.

[0133] (Adhesive layer 32) In the exterior material 3 for the energy storage device, the adhesive layer 32 is a layer that is placed on the base material layer 31 as needed in order to provide adhesion to the base material layer 31. That is, the adhesive layer 32 is provided between the base material layer 31 and the barrier layer 33.

[0134] The adhesive layer 32 is formed by an adhesive capable of bonding the base layer 31 and the barrier layer 33. The adhesive used to form the adhesive layer 32 may be a two-component curing adhesive or a one-component curing adhesive. Furthermore, the bonding mechanism of the adhesive used to form the adhesive layer 32 is not particularly limited and may be a chemical reaction type, solvent evaporation type, thermal melting type, hot pressure type, etc.

[0135] As for the resin component of the adhesive that can be used to form the adhesive layer 32, from the viewpoint of having excellent ductility, durability under high humidity conditions, yellowing suppression effect, and heat degradation suppression effect during heat sealing, and effectively suppressing the occurrence of delamination by suppressing the decrease in laminate strength between the base layer 31 and the barrier layer 33, two-component curable polyurethane adhesives; polyamide, polyester, or blended resins of these with modified polyolefins are preferred.

[0136] Furthermore, the adhesive layer 32 may be multilayered with different adhesive components. When the adhesive layer 32 is multilayered with different adhesive components, from the viewpoint of improving the lamination strength between the base material layer 31 and the barrier layer 33, it is preferable to select a resin with excellent adhesion to the base material layer 31 as the adhesive component arranged on the base material layer 31 side, and an adhesive component with excellent adhesion to the barrier layer 33 as the adhesive component arranged on the barrier layer 33 side. Specifically, when the adhesive layer 32 is multilayered with different adhesive components, preferred adhesive components arranged on the barrier layer 33 side include acid-modified polyolefins, metal-modified polyolefins, mixed resins of polyester and acid-modified polyolefins, and resins containing copolymerized polyesters.

[0137] The thickness of the adhesive layer 32 can be, for example, about 2 to 50 μm, preferably about 3 to 25 μm.

[0138] (Barrier layer 33) In the exterior material for energy storage devices, the barrier layer 33 is a layer that at least prevents moisture from entering.

[0139] Examples of barrier layers 33 include metal foils, vapor-deposited films, and resin layers that have 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 the barrier layer 33. Multiple layers of barrier layers 33 may be provided. It is preferable that the barrier layer 33 includes a layer made of a metal material. Specifically, examples of metal materials constituting the barrier layer 33 include aluminum alloys, 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.

[0140] In the barrier layer 33, the layer composed of the aforementioned metal material may include recycled metal material. Examples of recycled metal material include recycled aluminum alloy, stainless steel, titanium steel, or steel sheet. These recycled materials can each be obtained by known methods. Recycled aluminum alloy can be obtained, for example, by the manufacturing method described in International Publication No. 2022 / 092231. The barrier layer 33 may be composed solely of recycled material, or it may be composed of a mixture of recycled material and virgin material. Recycled metal material refers to metal material that has been recovered, isolated, and purified from various products used in the market or waste generated from manufacturing processes to make it reusable. Virgin metal material refers to new metal material refined from natural metal resources (raw materials) and is not recycled material.

[0141] From the viewpoint of improving the formability or conformability 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 or conformability, 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.

[0142] 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.

[0143] Specific examples of austenitic stainless steels that make up stainless steel foil include SUS304, SUS301, and SUS316L, with SUS304 being particularly preferred among these.

[0144] In the case of metal foil, the thickness of the barrier layer 33 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 33 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 33 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 33 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 33 is made of aluminum alloy foil, the above-mentioned range is particularly preferred. Furthermore, from the viewpoint of providing high formability and high rigidity to the exterior material 10 for the energy storage device, the thickness of the barrier layer 33 is preferably about 35 μm or more, more preferably about 45 μm or more, even more preferably about 50 μm or more, even more preferably about 55 μm or more, and also preferably about 200 μm or less, more preferably about 85 μm or less, even more preferably about 75 μm or less, and even more preferably about 70 μm or less. Preferred ranges are approximately 35-200 μm, 35-85 μm, 35-75 μm, 35-70 μm, 45-200 μm, 45-85 μm, 45-75 μm, 45-70 μm, 50-200 μm, 50-85 μm, 50-75 μm, 50-70 μm, 55-200 μm, 55-85 μm, 55-75 μm, and 55-70 μm. The high moldability of the exterior material 10 for energy storage devices facilitates deep drawing, which can contribute to increasing the capacity of energy storage devices. Furthermore, while increasing the capacity of an energy storage device increases its weight, the increased rigidity of the exterior material 10 for energy storage devices contributes to the high sealing performance of the energy storage device.Furthermore, in particular when the barrier layer 33 is composed 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 especially 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.

[0145] Furthermore, if the barrier layer 33 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 33 may 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 the barrier layer 33 has a corrosion-resistant coating, the barrier layer 33 includes the corrosion-resistant coating.

[0146] 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.

[0147] 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 polyacrylic acid, acrylate methacrylate copolymer, acrylate maleic acid copolymer, acrylate styrene copolymer, or derivatives thereof such as sodium salts, ammonium salts, or amine salts. Derivatives of polyacrylic acid, such as ammonium salts, sodium salts, or amine salts of polyacrylic acid, are particularly preferred. In this disclosure, polyacrylic acid means a polymer of acrylic acid. Furthermore, the acrylic resin is also preferably a copolymer of acrylic acid and a dicarboxylic acid or dicarboxylic acid anhydride, and also preferably an ammonium salt, sodium salt, or amine salt of a copolymer of acrylic acid and a dicarboxylic acid or dicarboxylic acid anhydride. Only one type of acrylic resin may be used, or two or more types may be mixed and used.

[0148] [ka]

[0149] [ka]

[0150] [ka]

[0151] [ka]

[0152] In general formulas (1) to (4), X represents a hydrogen atom, a hydroxyl group, an alkyl group, a hydroxyalkyl group, an allyl group, or a benzyl group. Also, R 1 and R 2 Each of these represents a hydroxyl group, an alkyl group, or a hydroxyalkyl group, either identical or different. In general formulas (1) to (4), X and R 1 and R 2Examples of the alkyl group represented by [alkyl group] include linear or branched alkyl groups having 1 to 4 carbon atoms such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, etc. Also, X, R 1 and R 2 Examples of the hydroxyalkyl group represented by [hydroxyalkyl group] include linear or branched alkyl groups having 1 to 4 carbon atoms with one hydroxy 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, 4-hydroxybutyl group, etc. In General Formulas (1) to (4), the alkyl groups and hydroxyalkyl groups represented by X, R 1 and R 2 may be the same or different from each other. In General Formulas (1) to (4), X is preferably a hydrogen atom, a hydroxy group or a hydroxyalkyl group. The number average molecular weight of the aminated phenol polymer having the repeating units represented by General Formulas (1) to (4) is preferably about 500 to 1,000,000, more preferably about 1,000 to 20,000. The aminated phenol polymer is produced, for example, by polycondensing a phenol compound or a naphthol compound and formaldehyde to produce a polymer composed of the repeating units represented by the above General Formula (1) or General Formula (3), and then introducing a functional group (-CH2NR 1 R 2 ) into the polymer obtained above using formaldehyde and an amine (R 1 R 2 NH). The aminated phenol polymer is used alone or in combination of two or more.

[0153] 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.

[0154] 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.

[0155] 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.

[0156] Furthermore, the composition of the corrosion-resistant coating can be analyzed, for example, using time-of-flight secondary ion mass spectrometry.

[0157] The amount of corrosion-resistant film to be formed on the surface of the barrier layer 33 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 33 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

[0158] 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.

[0159] 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.

[0160] (adhesive layer 34) In the exterior material 3 for the energy storage device, the adhesive layer 34 is a layer provided between the barrier layer 33 and the heat-fusible resin layer 35 as needed, in order to firmly bond the heat-fusible resin layer 35.

[0161] The adhesive layer 34 is formed by an adhesive capable of bonding the barrier layer 33 and the heat-fusible resin layer 35. The composition of the adhesive used to form the adhesive layer is not particularly limited, but examples include adhesives consisting of a polyester polyol compound and an alicyclic isocyanate compound.

[0162] The thickness of the adhesive layer 34 can be, for example, about 1 to 40 μm, preferably about 2 to 30 μm.

[0163] (Thermal adhesive resin layer 35) In the exterior material 3 for energy storage devices, the heat-sealable resin layer 35 is the innermost layer and is a layer that seals the energy storage device elements by heat-sealing the heat-sealable resin layers together during the assembly of the energy storage device. As described above, in the application of 2) (in which it is used as a heat-sealable resin layer for the exterior material for energy storage devices), the resin film 1 for energy storage devices of this disclosure is used as the heat-sealable resin layer 35 of the exterior material 3 for energy storage devices. As described above, in the case of application of 2) (in which it is used as a heat-sealable resin layer for the exterior material for energy storage devices), it is preferable that a pressure-sensitive adhesive layer 12 is present on the outermost surface of the exterior material for energy storage devices, and that a pressure-sensitive adhesive layer 12 is not provided on the barrier layer side of the heat-sealable resin layer.

[0164] The resin components used in the heat-fusible resin layer 35 are not particularly limited as long as they are heat-fusible, but for example, in the case of exterior materials for energy storage devices, polyolefins and cyclic polyolefins are generally used.

[0165] Specifically, the polyolefins include polyethylene such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; crystalline or amorphous 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); and ethylene-butene-propylene terpolymers. Among these polyolefins, polyethylene and polypropylene are preferred.

[0166] The 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, butadiene, isoprene, and the like. Examples of cyclic monomers that are constituent monomers of the cyclic polyolefin include cyclic alkenes such as norbornene; specifically, cyclic dienes such as cyclopentadiene, dicyclopentadiene, cyclohexadiene, norbornadiene, etc. Among these polyolefins, cyclic alkenes are preferred, and norbornene is more preferred. Styrene can also be used as a constituent monomer.

[0167] Among these resin components, preferred are crystalline or amorphous polyolefins, cyclic polyolefins, and blends thereof; more preferably, polyethylene, polypropylene, copolymers of ethylene and norbornene, and blends of two or more of these.

[0168] The heat-fusible resin layer 35 may be formed by a single resin component, or by a blended polymer combining two or more resin components. Furthermore, the heat-fusible resin layer 35 may be formed as a single layer, or it may be formed as two or more layers made of the same or different resin components.

[0169] Furthermore, the thickness of the heat-sealable resin layer 35 is not particularly limited, but is preferably about 2 to 2000 μm, more preferably about 5 to 1000 μm, and more preferably about 10 to 500 μm.

[0170] Furthermore, the resin film 1 of this disclosure can be particularly suitably applied to exterior materials for all-solid-state batteries, and the melting peak temperature of the heat-sealable resin layer 35 of the exterior material for all-solid-state batteries is preferably 150 to 250°C, more preferably 180 to 270°C, even more preferably 200 to 270°C, and even more preferably 200 to 250°C.

[0171] Furthermore, examples of resins included in the heat-sealable resin layer 35 of the exterior material for all-solid-state batteries include polyolefins such as polypropylene and polyethylene, acid-modified polyolefins such as acid-modified polypropylene and acid-modified polyethylene, and polybutylene terephthalate. Among these, polybutylene terephthalate has excellent heat resistance, so in the exterior material for all-solid-state batteries, the heat-sealable resin layer 35 is preferably formed from a polybutylene terephthalate film. In addition, because the heat-sealable resin layer 35 is formed from a polybutylene terephthalate film, it also has excellent adhesion to the resin layer A of the resin film 1 of this disclosure. The polybutylene terephthalate film forming the heat-sealable resin layer 35 may be formed by laminating a pre-prepared polybutylene terephthalate film with the adhesive layer 34, or the resin forming the polybutylene terephthalate film may be melt-extruded to form a film and then laminated with the adhesive layer 34.

[0172] The polybutylene terephthalate film may be an stretched polybutylene terephthalate film or an unstretched polybutylene terephthalate film, and an unstretched polybutylene terephthalate film is preferred.

[0173] The polybutylene terephthalate film is preferably composed of at least one of homopolybutylene terephthalate and copolymerized polybutylene terephthalate.

[0174] The heat-sealable resin layer 35 may be formed as a single layer, or it may be formed as two or more layers of the same or different resins. When the heat-sealable resin layer 35 is formed as two or more layers, at least one layer is preferably made of polybutylene terephthalate film, and the polybutylene terephthalate film is preferably the innermost layer of the exterior material for the all-solid-state battery. Furthermore, the layer that adheres to the adhesive layer 34 is preferably made of polybutylene terephthalate film. When the heat-sealable resin layer 35 is formed as two or more layers, the layer not made of polybutylene terephthalate film may be made of, for example, polyolefins such as polypropylene and polyethylene, or acid-modified polyolefins such as acid-modified polypropylene and acid-modified polyethylene. However, since polyolefins and acid-modified polyolefins have lower durability in high-temperature environments compared to polybutylene terephthalate or polyethylene terephthalate, it is preferable that the heat-sealable resin layer 35 is composed solely of a polybutylene terephthalate film such as a homo-PBT layer or a copolymer PBT layer, or solely of polyethylene terephthalate such as a PET layer.

[0175] The energy storage device of this disclosure is an energy storage device such as a battery (including capacitors, capacitors, etc.). The energy storage device of this disclosure may be either a primary battery or a secondary battery, but is preferably used as a secondary battery. The type of secondary battery is not particularly limited and examples include lithium-ion batteries, lithium-ion polymer batteries, all-solid-state batteries, lead-acid batteries, nickel-metal hydride batteries, nickel-cadmium batteries, nickel-iron batteries, nickel-zinc batteries, silver oxide-zinc batteries, metal-air batteries, polyvalent cation batteries, capacitors, capacitors, etc. Among these secondary batteries, the energy storage device of this disclosure is preferably a lithium-ion battery, a lithium-ion polymer battery, or an all-solid-state battery. [Examples]

[0176] The present disclosure will be described in detail below with reference to examples. However, the present disclosure is not limited to these examples.

[0177] <Manufacturing of resin films for energy storage devices> (Example 1) A laminated film with the lamination configuration shown in Table 1 (partially provided pressure-sensitive adhesive layer (adhesive PE, melting peak temperature 122.7℃, 30μm) / base film (r-PP film (melting peak temperature 125℃, 30μm)) was prepared and used as a resin film for energy storage devices. In the manufacture of the resin film for energy storage devices, an extruder and a T-die casting apparatus were used to obtain a polypropylene film (random polypropylene, melting peak temperature 125℃, thickness 30μm) as the base layer. Next, after slitting to a width of TD15mm, an adhesive PE layer with a width of 4.5mm and a thickness of 30μm was extruded from one end (the end that will be positioned on the opposite side from the energy storage device element when equipped to the energy storage device). Release PET was placed on the pressure-sensitive adhesive layer side and wound up, resulting in a partially provided pressure-sensitive adhesive layer (adhesive PE, melting peak temperature 122.7℃, thickness 30μm) / base film (r-PP film (melting peak temperature 125℃ A 30 μm thick sheet was obtained. This was cut to a size of TD15 mm × MD30 mm, and the release PET was peeled off to obtain a resin film for energy storage devices. In this case, the pressure-sensitive adhesive layer was TD4.5 mm × MD30 mm in size and rectangular along one side of the base film. The ratio of the area on the base film to the area on which the pressure-sensitive adhesive layer was formed was 30%.

[0178] In the <Evaluation of Opening the Energy Storage Device> described later, the central 7 mm of the TD15 mm of the resin film was designated as the sealing position. At this time, the pressure-sensitive adhesive layer was used so that 0.5 mm of the seal width was applied to the side opposite the energy storage device element.

[0179] (Example 2) A laminated film with the same lamination configuration as in Example 1 (partially provided pressure-sensitive adhesive layer (adhesive PE, melting peak temperature 122.7℃, 30μm) / base film (r-PP film (melting peak temperature 125℃, 30μm)) was prepared and used as a resin film for energy storage devices. The shape of the pressure-sensitive adhesive layer on the base film is rectangular along one side of the base film, and the pressure-sensitive adhesive layer is positioned on the side opposite to the energy storage device element. The ratio of the area on the base film to the area on which the pressure-sensitive adhesive layer is formed is 30%. However, in the <Evaluation of opening the energy storage device> section described later, the resin film of Example 2 was evaluated by cutting and removing the portion on which the pressure-sensitive adhesive layer was formed. Specifically, after sealing the film between the outer films as in Example 1, 2 mm of the 7 mm seal width was cut from the side opposite to the energy storage device element along the MD direction of the outer film (TD direction of the resin film). This removed the 2 mm seal portion including the pressure-sensitive adhesive layer for evaluation.

[0180] (Example 3) A laminated film with the lamination configuration shown in Table 1 (partially provided pressure-sensitive adhesive layer (primer layer 10 μm) / base film (r-PP film (melting peak temperature 135°C 5 μm) / LLDPE film (melting peak temperature 100°C 20 μm) / r-PP film (melting peak temperature 135°C 5 μm)) was prepared and used as a resin film for energy storage devices. The shape of the pressure-sensitive adhesive layer on the base film is three dots arranged at equal intervals in the center of the base film (arranged parallel to the edge face of the exterior material). The ratio of the area on which the pressure-sensitive adhesive layer is formed to the area on the base film is 20%. In the manufacture of the resin film for energy storage devices, an extruder and a T-die casting apparatus were used to form polypropylene (random polypropylene, melting peak temperature 135°C, thickness 20 μm) on both sides of polyethylene (LLDPE, melting peak temperature 100°C, thickness 20 μm) as the base layer. A PP film with a peak decomposition temperature of 135°C was extruded to a thickness of 5 μm to obtain a laminated film consisting of three layers: random PP (135°C, 5 μm) / random PP (100°C, 20 μm) / random PP (135°C, 5 μm). Next, after slitting to a width of 15 mm in the TD direction, a primer (acid-modified polypropylene) with a thickness of 10 μm was pattern-printed in the center of the 15 mm width, with φ6.2 mm dots spaced at 3 mm intervals in the MD direction, and a pressure-sensitive adhesive layer was placed. Release PET was placed on the pressure-sensitive adhesive layer side and the film was wound up, and the partially provided pressure-sensitive adhesive layer (primer layer) A laminated film was obtained by laminating a 10μm layer (r-PP film (melting peak temperature 135℃, 5μm)) / base film (r-PP film (melting peak temperature 100℃, 20μm) / r-PP film (melting peak temperature 135℃, 5μm)) in this order. This was cut to a size of TD15mm × MD30mm (the cutting position in the MD direction was adjusted so that three φ6.2mm primer dots were arranged in the MD direction), and the release PET was peeled off to obtain a resin film for energy storage devices.

[0181] In the <Evaluation of Opening the Energy Storage Device> described later, the central 7 mm of the 15 mm TD direction of the resin film was designated as the sealing position. At this time, a pressure-sensitive adhesive layer with a diameter of φ6.2 mm was placed in the exact center of the 7 mm sealing width.

[0182] (Example 4) A laminated film with the lamination configuration shown in Table 1 (partially provided pressure-sensitive adhesive layer (adhesive primer layer 10 μm) / base film (r-PP film (melting peak temperature 140℃ 5 μm) / r-PP film (melting peak temperature 125℃ 30 μm) / r-PP film (melting peak temperature 140℃ 5 μm)) was prepared and used as a resin film for energy storage devices. The shape of the pressure-sensitive adhesive layer on the base film is rectangular along one side of the base film, and the pressure-sensitive adhesive layer is positioned on the side opposite to the energy storage device element. The ratio of the area on the base film to the area on which the pressure-sensitive adhesive layer is formed is 20%. In the manufacture of the resin film for energy storage devices, an extruder and a T-die casting apparatus were used to apply polypropylene (random polypropylene, melting peak temperature 125℃, thickness 30 μm) to both sides of the base layer using polyethylene (random polypropylene, melting peak temperature 125℃, thickness 30 μm). Random polypropylene (melting peak temperature 140°C) was extruded to a thickness of 5 μm to obtain a resin film for energy storage devices with a three-layer structure of random PP (140°C, 5 μm) / random PP (125°C, 30 μm) / random PP (140°C, 5 μm). Next, after slitting to a width of 15 mm in the TD direction, a primer (acid-modified polypropylene) was applied by gravure coating to one end with a width of 3 mm and a thickness of 10 μm, and a release PET was placed on the pressure-sensitive adhesive layer side and wound up, partially forming the pressure-sensitive adhesive layer (primer layer). A 10μm layer was obtained, consisting of a base film, a r-PP film (melting peak temperature 140℃, 5μm), a r-PP film (melting peak temperature 125℃, 30μm), and a r-PP film (melting peak temperature 140℃, 5μm). This was cut to a size of TD15mm × MD30mm. The pressure-sensitive adhesive layer was installed to a size of TD3mm × MD30mm. The shape of the pressure-sensitive adhesive layer was rectangular along one side of the base film, and the pressure-sensitive adhesive layer was positioned on the side opposite to the energy storage device element. The ratio of the area on the base film to the area on which the pressure-sensitive adhesive layer was formed was 20%.

[0183] In the <Evaluation of Opening the Energy Storage Device> described later, the central 7 mm of the 15 mm TD direction of the resin film was designated as the sealing position. In this case, the pressure-sensitive adhesive layer was not included within the 7 mm sealing width, and was installed in a 3 mm width starting from a 1 mm gap.

[0184] (Example 5) Using an extruder and a T-die casting apparatus, polypropylene (random polypropylene, melting peak temperature 140°C) was extruded to a thickness of 5 μm onto both sides of a polyethylene (random polypropylene, melting peak temperature 125°C, thickness 30 μm) base layer, obtaining a laminated film with a three-layer structure of random PP (140°C, 5 μm) / random PP (125°C, 30 μm) / random PP (140°C, 5 μm). Next, the film was slit to a width of 15 mm in the TD direction, and then a primer (acid-modified polypropylene) was applied from one end to the other in a 7.5 mm width and 10 μm thickness using the gravure coating method. A release PET sheet was placed on the pressure-sensitive adhesive layer side and the film was wound up to obtain a partially formed pressure-sensitive adhesive layer (primer layer 10 μm) / base film (r-PP film (melting peak temperature 140°C 5 μm) / r-PP film (melting peak temperature 125°C 30 μm) / r-PP film (melting peak temperature 140°C 5 μm)). This was then cut to a size of TD 15 mm × MD 30 mm. In this case, the pressure-sensitive adhesive layer was installed to a size of TD 7.5 mm × MD 30 mm. The shape of the pressure-sensitive adhesive layer was rectangular along one side of the base film, and the pressure-sensitive adhesive layer was placed on the side opposite to the energy storage device element. The ratio of the area on the base film to the area on which the pressure-sensitive adhesive layer was formed was 50%.

[0185] In the <Evaluation of Opening the Energy Storage Device> described later, the central 7 mm of the 15 mm TD direction of the resin film was designated as the sealing position. In this case, the pressure-sensitive adhesive layer seals 3.5 mm away from the energy storage device element side, relative to the 7 mm sealing width.

[0186] (Example 6) Using an extruder and a T-die casting apparatus, polypropylene (random polypropylene, melting peak temperature 140°C) was extruded to a thickness of 5 μm onto both sides of a polyethylene (random polypropylene, melting peak temperature 125°C, thickness 30 μm) base layer, resulting in a laminated film with a three-layer structure of random PP (140°C, 5 μm) / random PP (125°C, 30 μm) / random PP (140°C, 5 μm). Next, the film was slit to a width of 15 mm in the TD direction, and then a primer (acid-modified polypropylene) was applied by gravure coating to one end of the film in a width of 9 mm and a thickness of 10 μm. A release PET sheet was placed on the pressure-sensitive adhesive layer side and the film was wound up to obtain a partially formed pressure-sensitive adhesive layer (primer layer 10 μm) / base film (r-PP film (melting peak temperature 140℃ 5 μm) / r-PP film (melting peak temperature 125℃ 30 μm) / r-PP film (melting peak temperature 140℃ 5 μm)). This was then cut to a size of TD 15 mm × MD 30 mm. In this case, the pressure-sensitive adhesive layer was installed to a size of TD 9 mm × MD 30 mm. The shape of the pressure-sensitive adhesive layer was rectangular along one side of the base film, and the pressure-sensitive adhesive layer was placed on the side opposite to the energy storage device element. The ratio of the area on the base film to the area on which the pressure-sensitive adhesive layer was formed was 60%.

[0187] In the <Evaluation of Opening the Energy Storage Device> described later, the central 7 mm of the 15 mm TD direction of the resin film was designated as the sealing position. In this case, the pressure-sensitive adhesive layer is sealed for 5 mm on the side opposite to the energy storage device element, relative to the 7 mm sealing width.

[0188] (Example 7) A resin film for energy storage devices was obtained using the same method as in Example 3. In Example 7, the resin film for energy storage devices was used as the heat-sealable resin layer of the exterior material for the energy storage device in the <Evaluation of opening the energy storage device> described later.

[0189] (Example 8) Polypropylene (random polypropylene, melting peak temperature 125°C, thickness 50 μm) was obtained as the base layer using an extruder and a T-die casting apparatus. Next, after slitting to a width of 15 mm in the TD direction, a primer (acid-modified polypropylene) was applied from one end to a width of 1.5 mm and a thickness of 10 μm by gravure coating. Release PET was placed on the pressure-sensitive adhesive layer side and the film was wound up to obtain a partially formed pressure-sensitive adhesive layer (primer layer 10 μm) / base film (r-PP film (melting peak temperature 125°C, 50 μm)). This was cut to a size of TD 15 mm × MD 30 mm. In this case, the pressure-sensitive adhesive layer was installed to a size of TD 1.5 mm × MD 30 mm. In this case, the shape of the pressure-sensitive adhesive layer was rectangular along one side of the base film, and the pressure-sensitive adhesive layer was placed on the side opposite to the energy storage device element side. The ratio of the area on the base film to the area on which the pressure-sensitive adhesive layer was formed was 10%.

[0190] In Example 8, in the <Evaluation of Opening the Energy Storage Device> described later, the resin film for the energy storage device was placed between the exterior material for the energy storage device and the lid.

[0191] (Example 9) Polypropylene (random polypropylene, melting peak temperature 125°C, thickness 80 μm) was obtained as the base layer using an extruder and a T-die casting apparatus. Next, after slitting to a width of 15 mm in the TD direction, a primer (acid-modified polypropylene) was applied by gravure coating to one end in a width of 6 mm and a thickness of 10 μm. Release PET was placed on the pressure-sensitive adhesive layer side and the film was wound up to obtain a partially formed pressure-sensitive adhesive layer (primer layer 10 μm) / base film (r-PP film (melting peak temperature 125°C, 80 μm)). This was cut to a size of TD 15 mm × MD 30 mm. In this case, the pressure-sensitive adhesive layer was installed to a size of TD 6 mm × MD 30 mm. In this case, the shape of the pressure-sensitive adhesive layer is rectangular along one side of the base film, and the pressure-sensitive adhesive layer is placed on the side opposite to the energy storage device element side. The ratio of the area on the base film to the area on which the pressure-sensitive adhesive layer is formed is 40%.

[0192] In Example 9, in the <Evaluation of Opening the Energy Storage Device> described later, the resin film for the energy storage device was placed between the lid body and the covering.

[0193] (Reference example 1) A laminated film with the lamination configuration shown in Table 1 (pressure-sensitive adhesive layer (adhesive PE, melting peak temperature 122.7°C, 33 μm) provided across the entire surface / base film (PPa film (melting peak temperature 140°C, 30 μm) / PEN film (melting peak temperature 265°C, 30 μm) / PPa film (melting peak temperature 140°C, 30 μm)) was prepared and used as a resin film for energy storage devices. The pressure-sensitive adhesive layer on the base film is formed across the entire surface of one side of the base film. The ratio of the area on which the pressure-sensitive adhesive layer is formed to the area on the base film is 100%.

[0194] (Reference example 2) A laminated film with the lamination configuration shown in Table 1 (pressure-sensitive adhesive layer provided across the entire surface (adhesive PE, melting peak temperature 122.7°C, 33 μm)) / base film (PPa film (melting peak temperature 140°C, 30 μm) / PEN film (melting peak temperature 265°C, 30 μm) / PPa film (melting peak temperature 140°C, 30 μm) / pressure-sensitive adhesive layer provided across the entire surface (adhesive PE film (melting peak temperature 122.7°C, 33 μm)) was prepared and used as a resin film for energy storage devices. The shape of the pressure-sensitive adhesive layer on the base film is formed across the entire surface of one side of the base film. The ratio of the area on which the pressure-sensitive adhesive layer is formed to the area on the base film is 100%.

[0195] (Comparative Example 1) Random polypropylene films (peak melting temperature 125°C, thickness 30 μm) as shown in Table 1 were prepared and used as resin films for energy storage devices. The resin films for energy storage devices do not have a pressure-sensitive adhesive layer.

[0196] <Measurement of sealing strength of resin film> (Manufacturing of exterior materials for energy storage devices) The exterior materials for energy storage devices used to measure the seal strength of the resin films obtained in the examples, reference examples, and comparative examples were manufactured according to the following procedure. Biaxially oriented polyethylene terephthalate (PET) film (12 μm thick) and biaxially oriented nylon film (15 μm thick) were prepared as base layers. Aluminum foil (JIS H4160:1994 A8021H-O (40 μm thick)) was prepared as a barrier layer. 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 The process was carried out 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).

[0197] Next, a biaxially oriented PET film (12 μm thick) and a biaxially oriented nylon film (15 μm thick) were laminated as base layers using a dry lamination method. On top of this, a barrier layer made of aluminum foil (JIS H4160:1994 A8021H-O, 40 μm thick) with acid-resistant coatings formed on both sides was laminated using a dry lamination method. Specifically, a two-component curing urethane adhesive (polyol compound and aromatic isocyanate compound) was applied to one side of the PET film to form an adhesive layer (3 μm thick after curing) on ​​the PET film. Then, the biaxially oriented nylon film was laminated. Next, a two-component curing urethane adhesive (polyol compound and aromatic isocyanate compound) was applied to one side of the aluminum foil with acid-resistant coatings formed on both sides to form an adhesive layer (3 μm thick after curing) on ​​the aluminum foil. Next, an adhesive layer on aluminum foil and a PET film / nylon film laminate were laminated in a direction where the nylon film was in contact with the aluminum foil. After this, an aging treatment was performed to create a laminate of a substrate layer / adhesive layer / barrier layer.

[0198] Next, maleic anhydride-modified polypropylene, which forms an adhesive layer (40 μm thick), and random polypropylene, which forms a heat-fusible resin layer (40 μm thick), were co-extruded onto the barrier layer of the laminate obtained above, thereby laminating the adhesive layer / heat-fusible resin layer on top of the barrier layer. Next, the obtained laminate was aged and heated to obtain an exterior material for an energy storage device consisting of a laminate in which a base layer (PET) / adhesive layer / base layer (ONY) / adhesive layer / barrier layer / adhesive layer / heat-fusible resin layer were laminated in this order.

[0199] (Measurement of seal strength of resin films in Examples 1-6, Reference Examples 1 and 2, and Comparative Example 1) The obtained exterior material for the energy storage device was cut to a size of MD150mm × TD60mm to prepare a sample. Next, with the heat-sealable resin layer of the sample facing inward, it was folded in half at the center position in the MD direction (75mm position), and the resin film of the aforementioned example, reference example, and comparative example, which had been cut to a size of MD30mm × TD15mm and had the release PET peeled off, was sandwiched between the two halves. The resin film was positioned so that one side of the longer edge (MD30mm) was located at the fold line. Here, for Examples 1, 2, 4-6, in which pressure-sensitive adhesive is provided in a rectangular area along one edge of the base film, shifted to the side opposite the energy storage device element, the resin film was positioned so that the side with the pressure-sensitive adhesive on the longer edge (MD30mm) was located at the fold line. For Example 3, where the pressure-sensitive adhesive is on the center line, Reference Examples 1 and 2, where the pressure-sensitive adhesive is on the entire surface, and Comparative Example 1, where there is no pressure-sensitive adhesive, the position of either of the two sides of the resin film relative to the fold line is not limited. In this state, a heel sealing machine with 7mm wide upper and lower metal heads was used to heat-seal the resin film between the heat-sealable resin layers at a temperature of 190°C, a surface pressure of 0.5MPa, and for 3 seconds to obtain a laminate. The sealing position was a 7mm wide strip extending in the MD direction, from a position 5mm below the fold to a position 12mm below. The obtained laminate was cut, and a strip-shaped test piece with a width of 15mm in the MD direction was obtained from the central part of the position where the resin film was sandwiched between the heat-sealable resin layers (both sides of the resin film were heat-sealed to the heat-sealable resin layer, but more precisely, the cut 30mm in the MD direction on both sides of the resin film was heat-sealed to the heat-sealable resin layer throughout, and the 15mm in the TD direction was partially heat-sealed to the heat-sealable resin layer with a width of 7mm). For Example 2, assuming that the pressure-sensitive adhesive layer would be cut off and removed after sealing in the manufacturing process of the energy storage device, the pressure-sensitive adhesive layer was cut off and removed. More specifically, the area containing the 4.5 mm pressure-sensitive adhesive layer located on the fold side of the 15 mm wide strip-shaped test specimen in the MD direction described above was removed by cutting 5 mm from the fold. The seal strength of the obtained test specimen was measured at measurement temperatures of 25°C and 60°C, respectively, in accordance with the provisions of JIS K7127:1999, as follows.Using a tensile testing machine with a constant temperature chamber, the sealing strength (N / 15mm) between the resin film and the heat-sealable resin layer was measured at a speed of 300 mm / min in measurement environments of 25°C and 60°C, respectively, with one outer casing material chucked against the opposite outer casing material at a peel angle of 180° (chuck distance of 50 mm).

[0200] (Measurement of the seal strength of the resin film in Example 7) In Example 7, the resin film for energy storage devices was used as the heat-sealable resin layer for the exterior material of the energy storage device. Specifically, a biaxially oriented PET film (thickness 12 μm) and a biaxially oriented nylon film (thickness 15 μm) were laminated in this order as base layers by dry lamination. On top of this, a barrier layer made of aluminum foil (JIS H4160:1994 A8021H-O, thickness 40 μm) with acid-resistant coatings formed on both sides was laminated by dry lamination. Specifically, a two-component curing urethane adhesive (polyol compound and aromatic isocyanate compound) was applied to one side of the PET film to form an adhesive layer (thickness 3 μm after curing) on ​​the PET film. Next, the biaxially oriented nylon film was laminated. Next, a two-component curing urethane adhesive (polyol compound and aromatic isocyanate compound) was applied to one side of the aluminum foil with acid-resistant coatings formed on both sides to form an adhesive layer (thickness 3 μm after curing) on ​​the aluminum foil. Next, an adhesive layer on aluminum foil and a PET film / nylon film laminate were laminated with the nylon film facing the aluminum foil, and then an aging treatment was performed to create a laminate of a base layer / adhesive layer / barrier layer. Then, a two-component curing urethane adhesive (polyol compound and aromatic isocyanate compound) was applied to the barrier layer side of the obtained laminate to form an adhesive layer (3 μm thick after curing) on ​​the aluminum foil. Furthermore, a resin film for energy storage devices was laminated on top of the adhesive layer as a heat-sealable resin layer by dry lamination. Next, the resulting laminate was aged and heated to obtain an exterior material for an energy storage device, in which PET (12 μm) / DL (3 μm) / ONY (15 μm) / DL (3 μm) / ALM (40 μm) / DL (3 μm) / random PP (135°C, 5 μm) / LLDPE (100°C, 40 μm) / random PP (135°C, 5 μm) / partially provided pressure-sensitive adhesive layer (primer layer 10 μm) were laminated in this order.

[0201] Next, the obtained exterior material for the energy storage device was cut to a size of MD150mm × TD60mm to obtain a sample. With the heat-sealable resin layer of the sample facing inward, it was folded in half at the center position in the MD direction (at the 75mm position), and a heel sealing machine with 7mm wide upper and lower metal heads was used to heat-seal the opposing heat-sealable resin layers (resin films) at a temperature of 190°C, a surface pressure of 0.5MPa, and for 3 seconds to obtain a laminate. The sealing position was a strip extending in the MD direction with a width of 7mm from a position 5mm below the fold to a position 12mm below. At this time, the opposing resin films were heat-sealed to each other. The obtained laminate was cut, and a strip-shaped test piece with a width of 15mm in the MD direction was obtained from the central part. The seal strength of the obtained test piece was measured at measurement temperatures of 25°C and 60°C, respectively, in accordance with the provisions of JIS K7127:1999, as follows. Using a tensile testing machine with a constant temperature chamber, the sealing strength (N / 15mm) between the heat-sealable resin layers, which are resin films, was measured at a speed of 300 mm / min in measurement environments of 25°C and 60°C, respectively, with one outer casing material chucked against the opposite outer casing material and pulled at a peel angle of 180° (chuck distance of 50 mm). The results are shown in Table 1.

[0202] (Measurement of the seal strength of the resin film in Example 8) In Example 8, one sheet of the exterior material for energy storage devices used in Examples 1-6 was cut to a size of 360 mm in the MD direction and 180 mm in the TD direction. The heat-sealable resin layer of the exterior material for energy storage devices was wrapped around a dummy cell (aluminum metal block) measuring 100 mm in length, 140 mm in width, and 30 mm in thickness, which mimicked an electrode body, so that it faced the block. One lid 60 (100 mm in length, 5 mm in width, and 30 mm in thickness, made of polypropylene, with a peak melting temperature of 140°C) was placed at each of the openings on both ends of the wrapped exterior material for energy storage devices. At this time, the resin film (15 mm x 30 mm) from Example 8, with the release PET removed, was sandwiched between one of the lids 60 and the exterior material for the energy storage device. After wrapping the lid 60 and dummy cell with tension applied, the parts where the exterior materials for the energy storage device face each other were heat-sealed using a dedicated machine for wrapping and sealing at a temperature of 220°C, a pressure of 1.0 MPa, and for 5 seconds, with a metal sealing bar on the upper side and silicone rubber on the lower side. Subsequently, the contact edge between the lid 60 and the exterior material for the energy storage device (the overlapping portion of the 5 mm wide peripheral surface of the lid and the exterior material for the energy storage device, which covers the lid when the exterior material for the energy storage device is wrapped around it) was heat-sealed at a temperature of 180°C, a pressure of 1.8 MPa, and for 3 seconds, to obtain a test sample in which the exterior of the energy storage device includes the exterior material for the energy storage device and the lid, and is interposed between the exterior material for the energy storage device and the lid. At this time, the resin film was placed so that the pressure-sensitive adhesive layer was located at the 1.5 mm end of the 5 mm wide seal width of the lid, opposite to the energy storage device element (in this case, an aluminum metal block simulating an electrode body), and then heat-sealed to create a test sample.

[0203] A cut was made in the test sample along the long side of the lid material (MD direction of the outer casing material) using a cutter, and the dummy cell that had been placed inside was removed. A 15 mm wide cut was made in the outer casing material for the energy storage device at the position where the resin film was sealed, and a test specimen was obtained in which the outer casing material for the energy storage device / resin film was 15 mm wide and sealed to the lid. The seal strength of the obtained test specimen was measured at measurement temperatures of 25°C and 60°C, respectively, in accordance with the provisions of JIS K7127:1999, as follows: Using a tensile testing machine with a constant temperature chamber, the seal strength (N / 15 mm) between the outer casing material / resin film / lid was measured at a speed of 300 mm / min in measurement environments of 25°C and 60°C, respectively, with one outer casing material and the opposite lid chucked and pulled at a peel angle of 180° (chuck distance 50 mm), and the seal strength (N / 15 mm) between the outer casing material for the energy storage device / resin film / lid at each temperature was measured. The results are shown in Table 1.

[0204] (Measurement of the seal strength of the resin film in Example 9) In Example 9, one sheet of the exterior material for the energy storage device used in Examples 1-6 was cut to a size of 360 mm in the MD direction and 180 mm in the TD direction. Furthermore, a lid 60 was prepared by insert molding a 1 mm thick polypropylene (melting peak temperature 140°C) coating 61 onto the periphery of the lid body 62 (98 mm long x 5 mm wide x 28 mm thick, made of aluminum). At this time, the resin film from Example 9, which had been cut to a size of 30 mm in the MD direction and 15 mm in the TD direction and had its release PET peeled off, was placed on one of the longitudinal sides of the lid body 62 and injected molded so that it was sandwiched between the lid body 62 and the coating 61. At this time, a resin film was placed on the lid body 62 such that the end opposite to the energy storage device element with the pressure-sensitive adhesive layer was positioned relative to the lid body 62, and injection molded to create a lid in which the resin film was interposed between the lid body and the covering. Similar to the measurement of the seal strength with resin film in Example 8, a dummy cell was prepared, and the exterior material for the energy storage device was wrapped around this dummy cell and the obtained lid. The portions where the heat-fusible resin layers of the exterior material for the energy storage device faced each other were heat-sealed using a dedicated machine for wrapping and sealing at a temperature of 220°C, a pressure of 1.0 MPa, and for 5 seconds, with a metal sealing bar on the upper side and silicone rubber on the lower side. Subsequently, the lid body 60 and the exterior material for the energy storage device were heat-sealed at a temperature of 200°C, a pressure of 1.8 MPa, and for 3 seconds, to obtain a test sample in which the exterior body of the energy storage device included the exterior material for the energy storage device and the lid, and the lid included a lid body and a covering that covers the periphery of the lid body, with the covering interposed between the lid body and the covering.

[0205] A cut was made in the test sample along the long side of the lid material (MD direction of the outer casing material) using a cutter, and the dummy cell that had been placed inside was removed. A 15 mm wide cut was made in the outer casing material for the energy storage device at the position including the resin film installation position, and a test specimen was obtained in which the outer casing material for the energy storage device / resin film was 15 mm wide and sealed to the lid. For the obtained test specimen, the seal strength at measurement temperatures of 25°C and 60°C was measured in accordance with the provisions of JIS K7127:1999 as follows: Using a tensile testing machine with a constant temperature chamber, one outer casing material and the opposite lid were chucked and pulled at a peel angle of 180° (chuck distance 50 mm) at a speed of 300 mm / min in measurement environments of 25°C and 60°C, respectively, and the seal strength (N / 15 mm) between the outer casing material for the energy storage device / resin film / lid at each temperature was measured. The results are shown in Table 1.

[0206] Furthermore, the seal strength was evaluated according to the following criteria. The results are shown in Table 1. A: The seal strength at 25°C and 60°C is 70N / 15mm or higher. B: The seal strength at 25°C is 70N / 15mm or higher, and the seal strength at 60°C is 30N / 15mm or higher but less than 70N / 15mm. C: The seal strength at 25°C is less than 70 N / 15 mm and / or the seal strength at 60°C is less than 30 N / 15 mm.

[0207] The measurement results of the seal strength show that the resin films for energy storage devices in Examples 1 to 9 have high seal strength at both 25°C and 60°C, and can seal the energy storage device elements. On the other hand, the resin films for energy storage devices in Reference Examples 1 and 2 have high seal strength at 25°C, and can seal the energy storage device elements, but at 60°C, the seal strength is low and cannot withstand the slight increase in internal pressure and load on the seal within the operating range of the energy storage device, and therefore cannot seal the energy storage device.

[0208] <Evaluation of the temporary fixing function of resin film> An exterior material for an energy storage device with a total thickness of 153 μm was prepared, consisting of the following layers laminated in this order: base layer (PET (thickness 12 μm) / adhesive (thickness 3 μm) / nylon (thickness 15 μm)) / adhesive layer (thickness 3 μm) / barrier layer (aluminum alloy foil, thickness 40 μm) / adhesive layer (maleic anhydride modified polypropylene, thickness 40 μm) / heat-sealable resin layer (polypropylene, melting peak temperature 140°C, thickness 40 μm). One test piece was prepared, cut to a size of 8 cm (width in the z direction) x 19 cm (length in the x direction). The test piece was folded in half so that the heat-sealable resin layer was on the inside. Next, a resin film was placed between the heat-sealable resin layers on the shorter side (width). The size of the resin film was 3 cm (width in the z direction) x 1.5 cm (length in the x direction). At this time, the resin film was not secured from the outside by tape or by applying heat to temporarily fix it. In this state, the sample, along with the outer casing material for the energy storage device, was lifted to a height of 30 cm, keeping the sample parallel to the workbench, and then dropped onto the workbench. After repeating this process twice, and anticipating that the sample might move during heat sealing in the manufacturing of the energy storage device, the short side of the test specimen, which had the resin film positioned on it, was heat-sealed under the conditions of a pressure of 0.5 MPa, a temperature of 190°C, and a seal width of 7 mm. At this time, both sides of the resin film were heat-sealed to the heat-sealable resin layer. After sealing, the sample was visually inspected to check for any detachment or displacement of the resin film.

[0209] (Evaluation criteria for temporary fixation function) A: In the evaluation of the temporary fixing function, there was no fall or misalignment of the resin film. B: In the evaluation of the temporary fixing function's fall and misalignment, the resin film is slightly misaligned (misalignment from the desired fixing position is within 0.5 mm). C: In the evaluation of the temporary fixing function's fall and misalignment, the resin film is misaligned (misalignment from the desired fixing position exceeds 0.5 mm) or the resin film has fallen off.

[0210] <Evaluation of energy storage devices after opening them up> (Resin films for energy storage devices in Examples 1-6) An exterior material for an energy storage device with a total thickness of 153 μm was prepared, consisting of the following layers laminated in this order: base layer (PET (thickness 12 μm) / adhesive (thickness 3 μm) / nylon (thickness 15 μm)) / adhesive layer (thickness 3 μm) / barrier layer (aluminum alloy foil, thickness 40 μm) / adhesive layer (maleic anhydride modified polypropylene, thickness 40 μm) / heat-sealable resin layer (polypropylene, melting peak temperature 140°C, thickness 40 μm). One test piece was prepared, cut to a size of 8 cm (width in the z direction) x 19 cm (height in the x direction). The test piece was folded in half so that the heat-sealable resin layer was on the inside, and a φ11 mm hole was made in one place on one side (exactly in the center of the rectangle measuring 8 cm wide x 9.5 cm high). A jig for installing a tube to supply air into the sample during the opening test was attached to the position of the hole.

[0211] Next, a resin film, from which the release PET had been peeled off, was placed between the heat-sealable resin layers on the shorter (horizontal) side. The size of the resin film was the same as in the examples, reference examples, and comparative examples, MD30mm × TD15mm, and here, to match the size expression for exterior materials for energy storage devices, it was expressed as 3cm horizontally (z direction) × 1.5cm vertically (x direction). The resin film was positioned so that its horizontal (z direction) and vertical (x direction) coincided with the test specimen. More specifically, in the horizontal (z direction), the center positions of the test specimen and the resin film coincided, and in the vertical (x direction), the bottom edge of the resin film in the vertical (x direction) was aligned with the 8cm short side which was the bottom edge of the vertical (x direction) of the test specimen. Here, for the resin films of Examples 1, 2, 4-6, in which pressure-sensitive adhesive is applied to a rectangular area along one side of the base film, shifted to the side opposite to the energy storage device element, the resin film is positioned so that one of the two 3cm sides of the resin film, on which the pressure-sensitive adhesive is applied, aligns with the 8cm short side that forms the bottom edge (x direction) of the test piece. For Example 3, where the pressure-sensitive adhesive is on the center line; Reference Examples 1 and 2, where the pressure-sensitive adhesive covers the entire surface; and Comparative Example 1, where no pressure-sensitive adhesive is present, the orientation of the resin film with respect to the 8cm short side that forms the bottom edge (x direction) of the test piece is not limited. Next, the short side on which the resin film of the energy storage device exterior material, which is the test piece, is positioned, and the two long sides are heat-sealed under the conditions of pressure 0.5 MPa, temperature 190°C, seal width 7 mm, and sealing time 3 seconds. Here, in the heat sealing along the short side, the central 7 mm of the 15 mm vertical (x direction) of the sandwiched resin film is sealed. More specifically, the test specimen and resin film were heat-sealed so that a line 7.5 mm above the lower vertical (x-direction) edge of the aligned specimen and resin film coincided with a line 3.5 mm above the center of the 7 mm seal width. At this time, both sides of the resin film were heat-sealed to the heat-sealable resin layer. A thermocouple was attached to the test sample and placed in an oven set to room temperature (25°C). Air was introduced into the sample, and when the pressure reached 0.1 MPa, the air supply and exhaust were shut off to maintain a constant pressure. Next, the test sample temperature was heated from room temperature (25°C) at a heating rate of 6°C / min until it reached 150°C. The temperature at which the sample was opened was defined as the opening temperature. The results are shown in Table 1.

[0212] (Resin film for energy storage device in Example 7) In Example 7, the resin film for energy storage devices was used as the heat-sealable resin layer for the exterior material of the energy storage device. Specifically, a biaxially oriented PET film (thickness 12 μm) and a biaxially oriented nylon film (thickness 15 μm) were laminated in this order as base layers by dry lamination. On top of this, a barrier layer made of aluminum foil (JIS H4160:1994 A8021H-O, thickness 40 μm) with acid-resistant coatings formed on both sides was laminated by dry lamination. Specifically, a two-component curing urethane adhesive (polyol compound and aromatic isocyanate compound) was applied to one side of the PET film to form an adhesive layer (thickness 3 μm after curing) on ​​the PET film. Next, the biaxially oriented nylon film was laminated. Next, a two-component curing urethane adhesive (polyol compound and aromatic isocyanate compound) was applied to one side of the aluminum foil with acid-resistant coatings formed on both sides to form an adhesive layer (thickness 3 μm after curing) on ​​the aluminum foil. Next, an adhesive layer on aluminum foil and a PET film / nylon film laminate were laminated with the nylon film facing the aluminum foil, and then an aging treatment was performed to create a laminate of a base layer / adhesive layer / barrier layer. Then, a two-component curing urethane adhesive (polyol compound and aromatic isocyanate compound) was applied to the barrier layer side of the obtained laminate to form an adhesive layer (3 μm thick after curing) on ​​the aluminum foil. Furthermore, a resin film for energy storage devices was laminated on top of the adhesive layer as a heat-sealable resin layer by dry lamination. Next, the resulting laminate was aged and heated to obtain an exterior material for a power storage device, in which PET (12 μm) / DL (3 μm) / ONY (15 μm) / DL (3 μm) / ALM (40 μm) / DL (3 μm) / random PP (135℃, 5 μm) / LLDPE (100℃, 40 μm) / random PP (135℃, 5 μm) / partially provided pressure-sensitive adhesive layer (primer layer 10 μm) were laminated in this order. Next, one rectangular test piece was prepared by cutting the exterior material for the power storage device to a size of 8 cm horizontally (z direction) x 19 cm vertically (x direction). The test piece was folded in half so that the heat-sealable resin layer was on the inside, and a φ11 mm hole was made in one place on one side (exactly in the center of the rectangle measuring 8 cm horizontally x 9.5 cm vertically).A jig was attached to the location of the drilled hole to install a tube for introducing air into the sample during the opening test.

[0213] Next, the short side and two long sides of the test specimen, which is the exterior material for the energy storage device, were heat-sealed under the conditions of a pressure of 0.5 MPa, a temperature of 190°C, a seal width of 7 mm, and for 3 seconds. Here, in the heat sealing along the short side, the heat sealing was performed so that the 3.5 mm line in the center of the 7 mm seal width coincided with a line 7.5 mm above the bottom edge in the vertical direction of the test specimen. At this time, both sides of the opposing resin films, that is, the heat-sealable resin layers of the opposing exterior materials for the energy storage device, were heat-sealed to each other. A thermocouple was attached to the test sample and placed in an oven set to room temperature (25°C). Air was blown into the sample, and when the pressure reached 0.1 MPa, the air supply and exhaust were shut off to maintain a constant pressure. Next, the test sample temperature was heated from room temperature (25°C) at a heating rate of 6°C / min until it reached 150°C. The temperature at which the sample was opened was defined as the opening temperature.

[0214] (Resin film for energy storage device in Example 8) In Example 8, one sheet of the exterior material for energy storage devices used in Examples 1-6 was cut to a size of 360 mm in the MD direction and 180 mm in the TD direction. A dummy cell (aluminum metal block with a φ11 mm hole in the center for attaching a jig to supply air during an opening test), measuring 100 mm in length, 140 mm in width, and 30 mm in thickness, which mimicked an electrode body, was wrapped around the exterior material for energy storage devices so that the heat-sealable resin layer of the exterior material for energy storage devices faced the block side. At this time, a φ11 mm hole was also made in the wrapped outer layer material for energy storage devices at the same position as the dummy cell. One lid 60 (100 mm in length, 5 mm in width, and 30 mm in thickness, made of polypropylene, with a melting peak temperature of 140°C) was set on each end of the wrapped exterior material for energy storage devices. At this time, the resin film (15 mm x 30 mm) from Example 8, with the release PET peeled off, was sandwiched between one of the lids 60 and the exterior material for the energy storage device. After wrapping the lid 60 and dummy cell together and applying tension, the parts where the exterior materials for the energy storage device meet facing each other were heat-sealed using a dedicated machine for wrapping and sealing at a temperature of 220°C, a pressure of 1.0 MPa, and for 5 seconds, with a metal sealing bar on the upper side and silicone rubber on the lower side. Subsequently, the contact edge between the lid 60 and the exterior material for the energy storage device (the part where the 5 mm wide peripheral surface of the lid and the exterior material for the energy storage device overlap, covering the lid when the exterior material for the energy storage device is wrapped around it) was heat-sealed at a temperature of 180°C, a pressure of 1.8 MPa, and for 3 seconds, to obtain a test sample in which the exterior of the energy storage device includes the exterior material for the energy storage device and the lid, and is interposed between the exterior material for the energy storage device and the lid. At this time, the resin film was placed so that the pressure-sensitive adhesive layer was located at the 1.5 mm end of the lid's 5 mm width seal, opposite the energy storage device element, and then heat-sealed to create the test sample.

[0215] A jig for supplying air and a thermocouple were attached to the test sample, and the sample was placed in an oven set to room temperature (25°C). A φ5mm tube was attached to the jig. Air was supplied to the sample through the attached tube, and when the pressure reached 0.1 MPa, the supply and discharge of air were shut off to maintain a constant pressure. Next, the test sample was heated from room temperature (25°C) at a heating rate of 6°C / min until the temperature reached 150°C. The temperature at which the sample was opened was defined as the opening temperature.

[0216] (Resin film for energy storage device in Example 9) In Example 9, one sheet of the exterior material for the energy storage device used in Examples 1-6 was cut to a size of 360 mm in the MD direction and 180 mm in the TD direction. Furthermore, a lid 60 was prepared by insert molding a 1 mm thick polypropylene (melting peak temperature 140°C) coating 61 onto the periphery of the lid body 62 (98 mm long x 5 mm wide x 28 mm thick, made of aluminum). At this time, the resin film from Example 9, which had been cut to a size of 30 mm in the MD direction and 15 mm in the TD direction and had its release PET peeled off, was placed on one of the longitudinal sides of the lid body 62 and injected molded so that it was sandwiched between the lid body 62 and the coating 61. At this time, a resin film was placed on the lid body 62 such that the end opposite to the energy storage device element on which the pressure-sensitive adhesive layer is provided was positioned, and injection molding was performed to create a lid in which the resin film was interposed between the lid body and the covering. Similar to the measurement of the seal strength with resin film in Example 8, a dummy cell was prepared, and a sample was made using this dummy cell and the obtained lid in the same manner as in Example 8. A test sample was obtained in which the exterior of the energy storage device included an exterior material for the energy storage device and a lid, and the lid included a lid body and a covering that covers the periphery of the lid body, with the covering interposed between the lid body and the covering.

[0217] An opening temperature test was conducted using the same method as in Example 8, and the temperature at which the sample was opened was defined as the opening temperature.

[0218] (Evaluation Criteria) A: The resin film was opened at a temperature between 80°C and 125°C. B: The product was opened at the location of the resin film at a temperature between 60°C and 80°C. C: Opened at the location of the resin film at a temperature below 60℃. D: The film was opened in a location other than where the resin film was installed.

[0219] <Measurement of seal strength A at opening temperature A> The seal strength A of the resin film for energy storage devices at opening temperature A was measured. The results are shown in Table 1. First, in order to measure the seal strength A at the temperature at which the outer material for energy storage devices opens (opening temperature A), the opening temperature A was determined by performing an opening test according to the following procedure. The procedures for the opening tests for each example, reference example, and comparative example are the same as those described in the aforementioned <Evaluation of Opening of Energy Storage Devices> for (resin films for energy storage devices of Examples 1-6), (resin films for energy storage devices of Example 7), (resin films for energy storage devices of Example 8), and (resin films for energy storage devices of Example 9). Furthermore, the procedure for measuring the seal strength A at the opening temperature A determined in the opening tests for each example, reference example, and comparative example follows the procedures described in the aforementioned <Measurement of Seal Strength of Resin Films> for (measurement of seal strength of resin films of Examples 1-6, Reference Examples 1, 2, and Comparative Example 1), (measurement of seal strength of resin film of Example 7), (measurement of seal strength of resin film of Example 8), (measurement of seal strength of resin film of Example 9), (resin film for energy storage devices of Example 8), and (resin film for energy storage devices of Example 9). The difference is that the temperature setting of the measurement environment is not 25°C and 60°C, but rather the respective opening temperature A determined for each example, reference example, and comparative example. Details are explained below.

[0220] (Procedure for opening the film: Resin films of Examples 1-6, Reference Examples 1 and 2, and Comparative Example 1) An exterior material for an energy storage device with a total thickness of 153 μm was prepared, consisting of a base layer (PET (thickness 12 μm) / adhesive (thickness 3 μm) / nylon (thickness 15 μm)) / adhesive layer (thickness 3 μm) / barrier layer (aluminum alloy foil, thickness 40 μm) / adhesive layer (maleic anhydride modified polypropylene, thickness 40 μm) / heat-sealable resin layer (polypropylene, melting peak temperature 140°C, thickness 40 μm) laminated in this order. One rectangular test piece was prepared, cut to the size of TD80 mm × MD190 mm. Hereafter, TD80 mm of the test piece will be referred to as the short side, and MD190 mm of the test piece and MD95 mm when the test piece is folded in half will both be referred to as the long side. The test piece was folded in half so that the heat-sealable resin layer was on the inside, and a φ11 mm hole was made in one place on one side (exactly in the center of the rectangle with a short side of 80 mm and a long side of 95 mm). A jig was attached to the location of the drilled hole to install a tube for introducing air into the sample during the opening test.

[0221] Next, a resin film, from which the release PET had been peeled off, was placed between the heat-sealable resin layers on the shorter side. The size of the resin film is the same as in the examples, reference examples, and comparative examples, MD30mm × TD15mm, but here, to match the representation of the exterior material for energy storage devices, it is set to 30mm on the long side × 15mm on the short side. Furthermore, since the test piece and the resin film become one unit by heat sealing, the vertical and horizontal directions are set based on the folded test piece. More specifically, when the folded test piece is viewed from above, the folded test piece is a rectangle with a short side of 80mm and a long side of 95mm. The vertical direction is defined with the 95mm fold on the upper side and the two 95mm ends opposite this fold on the lower side, and the horizontal direction is defined with the two 80mm sides on the right and left sides. The resin film was positioned on the folded test specimen so that the long side (30 mm) of the resin film coincided with the short side (80 mm) of the test specimen, and the short side (15 mm) of the resin film coincided with the long side (95 mm) of the test specimen. More specifically, in the horizontal direction, the center position of the test specimen (40 mm midway along the 80 mm short side) coincided with the center position of the resin film (15 mm midway along the 30 mm long side), and in the vertical direction, the long side (30 mm), which is the lower vertical end of the resin film, aligned with the 80 mm short side, which is the lower vertical end of the test specimen. Here, for the resin films of Examples 1, 2, 4-6, in which pressure-sensitive adhesive is applied to a rectangular area along one side of the base film, shifted to the side opposite the energy storage device element, the resin film was positioned so that one of the two 30 mm sides of the resin film, on which the pressure-sensitive adhesive is applied, coincided with the 80 mm short side, which is the lower vertical end of the test specimen. For Example 3, where the pressure-sensitive adhesive is located at the center line; Reference Examples 1 and 2, where the pressure-sensitive adhesive covers the entire surface; and Comparative Example 1, where no pressure-sensitive adhesive is present, the orientation of the resin film relative to the 80 mm short side, which is the lower vertical end of the test specimen, is not limited. Next, the short side on which the resin film of the test specimen, which is the exterior material for an energy storage device, is placed, and the two long sides were heat-sealed under the conditions of a pressure of 0.5 MPa, a temperature of 190°C, a seal width of 7 mm, and a sealing time of 3 seconds. In this case, when heat-sealing along the short side, the central 7 mm of the 15 mm vertical length of the sandwiched resin film is sealed.More specifically, the test specimen and resin film are heat-sealed so that a line 7.5 mm above the aligned vertical bottom edge aligns with a 3.5 mm line in the center of the 7 mm seal width. At this time, both sides of the resin film are heat-sealed to the heat-sealable resin layer. A thermocouple was attached to the test sample and placed in an oven set to room temperature (25°C). Air was introduced into the sample, and when the pressure reached 0.1 MPa, the air supply and exhaust were shut off to maintain a constant pressure. Next, the test sample temperature was heated from room temperature (25°C) at a heating rate of 6°C / min until it reached 150°C. The temperature at which the sample was opened was defined as the opening temperature.

[0222] (Opening test procedure: Resin film of Example 7) In Example 7, the resin film for energy storage devices was used as the heat-sealable resin layer for the exterior material of the energy storage device. Specifically, a biaxially oriented PET film (thickness 12 μm) and a biaxially oriented nylon film (thickness 15 μm) were laminated in this order as base layers by dry lamination. On top of this, a barrier layer made of aluminum foil (JIS H4160:1994 A8021H-O, thickness 40 μm) with acid-resistant coatings formed on both sides was laminated by dry lamination. Specifically, a two-component curing urethane adhesive (polyol compound and aromatic isocyanate compound) was applied to one side of the PET film to form an adhesive layer (thickness 3 μm after curing) on ​​the PET film. Next, the biaxially oriented nylon film was laminated. Next, a two-component curing urethane adhesive (polyol compound and aromatic isocyanate compound) was applied to one side of the aluminum foil with acid-resistant coatings formed on both sides to form an adhesive layer (thickness 3 μm after curing) on ​​the aluminum foil. Next, an adhesive layer on aluminum foil and a PET film / nylon film laminate were laminated with the nylon film facing the aluminum foil, and then an aging treatment was performed to create a laminate of a base layer / adhesive layer / barrier layer. Then, a two-component curing urethane adhesive (polyol compound and aromatic isocyanate compound) was applied to the barrier layer side of the obtained laminate to form an adhesive layer (3 μm thick after curing) on ​​the aluminum foil. Furthermore, a resin film for energy storage devices was laminated on top of the adhesive layer as a heat-sealable resin layer by dry lamination. Next, the resulting laminate was aged and heated to obtain an exterior material for energy storage devices, in which PET (12 μm) / DL (3 μm) / ONY (15 μm) / DL (3 μm) / ALM (40 μm) / DL (3 μm) / random PP (135℃, 5 μm) / LLDPE (100℃, 40 μm) / random PP (135℃, 5 μm) / partially provided pressure-sensitive adhesive layer (primer layer 10 μm) were laminated in this order. Next, one rectangular test piece was prepared by cutting the exterior material for energy storage devices to a size of TD 80 mm × MD 190 mm. The test piece was folded in half so that the heat-sealable resin layer was on the inside, and a φ11 mm hole was made in one place on one side (exactly in the center of the rectangle with a short side of 80 mm and a long side of 95 mm).A jig was attached to the location of the drilled hole to install a tube for introducing air into the sample during the opening test.

[0223] Next, the short side and two long sides of the test specimen, which is the exterior material for the energy storage device, were heat-sealed under the conditions of a pressure of 0.5 MPa, a temperature of 190°C, a seal width of 7 mm, and for 3 seconds. Here, in the heat sealing along the short side, the heat sealing was performed so that the 3.5 mm line in the center of the 7 mm seal width coincided with a line 7.5 mm above the bottom edge in the vertical direction of the test specimen. At this time, both sides of the opposing resin films, that is, the heat-sealable resin layers of the opposing exterior materials for the energy storage device, were heat-sealed to each other. A thermocouple was attached to the test sample and placed in an oven set to room temperature (25°C). Air was blown into the sample, and when the pressure reached 0.1 MPa, the air supply and exhaust were shut off to maintain a constant pressure. Next, the test sample temperature was heated from room temperature (25°C) at a heating rate of 6°C / min until it reached 150°C. The temperature at which the sample was opened was defined as the opening temperature.

[0224] (Opening test procedure: Resin film of Example 8) In Example 8, one sheet of the exterior material for the energy storage device used in the above-mentioned (opening test procedure: resin film of Examples 1-6) was cut to a size of 360 mm in the MD direction and 180 mm in the TD direction. A dummy cell (aluminum metal block with a φ11 mm hole in the center for attaching a jig to send air during the opening test), measuring 100 mm in length, 140 mm in width, and 30 mm in thickness, which simulates an electrode body, was wrapped with the heat-sealable resin layer of the above-mentioned exterior material for the energy storage device facing the block side. At this time, a φ11 mm hole was also made in the wrapped outer layer material for the energy storage device at the same position as the dummy cell. One lid 60 (100 mm in length, 5 mm in width, and 30 mm in thickness, polypropylene, melting peak temperature 140°C) was set on each end of the wrapped outer layer material for the energy storage device. At this time, the resin film (15 mm x 30 mm) from Example 8, with the release PET peeled off, was sandwiched between one of the lids 60 and the exterior material for the energy storage device. After wrapping the lid 60 and dummy cell together and applying tension, the parts where the exterior materials for the energy storage device meet facing each other were heat-sealed using a dedicated machine for wrapping and sealing at a temperature of 220°C, a pressure of 1.0 MPa, and for 5 seconds, with a metal sealing bar on the upper side and silicone rubber on the lower side. Subsequently, the contact edge between the lid 60 and the exterior material for the energy storage device (the part where the 5 mm wide peripheral surface of the lid and the exterior material for the energy storage device overlap, covering the lid when the exterior material for the energy storage device is wrapped around it) was heat-sealed at a temperature of 180°C, a pressure of 1.8 MPa, and for 3 seconds, to obtain a test sample in which the exterior of the energy storage device includes the exterior material for the energy storage device and the lid, and is interposed between the exterior material for the energy storage device and the lid. At this time, the resin film was placed so that the pressure-sensitive adhesive layer was located at the 1.5 mm end of the lid's 5 mm width seal, opposite the energy storage device element, and then heat-sealed to create the test sample.

[0225] A jig for supplying air and a thermocouple were attached to the test sample, and the sample was placed in an oven set to room temperature (25°C). A φ5mm tube was attached to the jig. Air was supplied to the sample through the attached tube, and when the pressure reached 0.1 MPa, the supply and discharge of air were shut off to maintain a constant pressure. Next, the test sample was heated from room temperature (25°C) at a heating rate of 6°C / min until the temperature reached 150°C. The temperature at which the sample was opened was defined as the opening temperature.

[0226] (Opening test procedure: Resin film of Example 9) In Example 9, the exterior material for the energy storage device used in the above-mentioned (opening test procedure: resin film of Examples 1-6) was used. Furthermore, a cover 60 (100 mm long x 5 mm wide x 30 mm thick) was prepared by insert molding a 1 mm thick polypropylene (melting peak temperature 140°C) as a covering 61 around the periphery of the lid body 62 (98 mm long x 5 mm wide x 28 mm thick, aluminum material). At this time, the resin film from Example 9, which had been cut to a size of 30 mm in the MD direction x 15 mm in the TD direction and had its release PET peeled off, was placed on one of the longitudinal sides of the lid body 62 and injected molded so that it was sandwiched between the lid body 62 and the covering 61. Using the obtained lid, a sample was prepared in the same manner as in Example 8. A test sample was obtained in which the exterior of a power storage device includes an exterior material for a power storage device and a cover, and the cover includes a cover body and a covering that covers the periphery of the cover body, and the covering is interposed between the cover body and the covering.

[0227] An opening temperature test was conducted using the same method as in Example 8, and the temperature at which the sample was opened was defined as the opening temperature.

[0228] <Measurement of the seal strength A of the resin film at opening temperature A determined in the opening test> (Manufacturing of exterior materials for energy storage devices) The exterior materials for energy storage devices used to measure the seal strength of the resin films obtained in the examples, reference examples, and comparative examples were manufactured according to the following procedure. Biaxially oriented polyethylene terephthalate (PET) film (12 μm thick) and biaxially oriented nylon film (15 μm thick) were prepared as base layers. Aluminum foil (JIS H4160:1994 A8021H-O (40 μm thick)) was prepared as a barrier layer. 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 The process was carried out 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).

[0229] Next, a biaxially oriented PET film (12 μm thick) and a biaxially oriented nylon film (15 μm thick) were laminated as base layers using a dry lamination method. On top of this, a barrier layer made of aluminum foil (JIS H4160:1994 A8021H-O, 40 μm thick) with acid-resistant coatings formed on both sides was laminated using a dry lamination method. Specifically, a two-component curing urethane adhesive (polyol compound and aromatic isocyanate compound) was applied to one side of the PET film to form an adhesive layer (3 μm thick after curing) on ​​the PET film. Then, the biaxially oriented nylon film was laminated. Next, a two-component curing urethane adhesive (polyol compound and aromatic isocyanate compound) was applied to one side of the aluminum foil with acid-resistant coatings formed on both sides to form an adhesive layer (3 μm thick after curing) on ​​the aluminum foil. Next, an adhesive layer on aluminum foil and a PET film / nylon film laminate were laminated in a direction where the nylon film was in contact with the aluminum foil. After this, an aging treatment was performed to create a laminate of a substrate layer / adhesive layer / barrier layer.

[0230] Next, maleic anhydride-modified polypropylene, which forms an adhesive layer (40 μm thick), and random polypropylene, which forms a heat-fusible resin layer (40 μm thick), were co-extruded onto the barrier layer of the laminate obtained above, thereby laminating the adhesive layer / heat-fusible resin layer on top of the barrier layer. Next, the obtained laminate was aged and heated to obtain an exterior material for an energy storage device consisting of a laminate in which a base layer (PET) / adhesive layer / base layer (ONY) / adhesive layer / barrier layer / adhesive layer / heat-fusible resin layer were laminated in this order.

[0231] (Measurement procedure for seal strength A at opening temperature A determined by opening tests: Resin films of Examples 1-6, Reference Examples 1 and 2, and Comparative Example 1) The obtained exterior material for the energy storage device was cut to a size of MD150mm × TD60mm to prepare a sample. Next, with the heat-sealable resin layer of the sample facing inward, it was folded in half at the center position in the MD direction (75mm position), and the resin film of the aforementioned example, reference example, and comparative example, which was cut to a size of MD30mm × TD15mm and had the release PET peeled off, was sandwiched between the two halves. The resin film was positioned so that one side of the long side (MD30mm) was located at the fold line. Here, for Examples 1, 2, 4-6, in which pressure-sensitive adhesive is provided in a rectangular area along one side of the base film, shifted to the side opposite the energy storage device element, the resin film was positioned so that the side with the pressure-sensitive adhesive on the long side (MD30mm) was located at the fold line. For Example 3, where the pressure-sensitive adhesive is on the center line, Reference Examples 1 and 2, where the pressure-sensitive adhesive is on the entire surface, and Comparative Example 1, where there is no pressure-sensitive adhesive, the position of either of the two sides of the resin film relative to the fold line is not limited. In this state, a heel sealing machine with 7mm wide upper and lower metal heads was used to heat-seal the resin film between the heat-sealable resin layers at a temperature of 190°C, a surface pressure of 0.5 MPa, and for 3 seconds to obtain a laminate. The sealing position was a 7mm wide strip extending in the MD direction, from a position 5mm below the fold to a position 12mm below. The obtained laminate was cut, and a strip-shaped test piece with a width of 15mm in the MD direction was obtained from the center of the position where the resin film was sandwiched between the heat-sealable resin layers (the entire 15mm cut in the MD direction on both sides of the resin film, and 7mm wide in the TD direction, were heat-sealed to the heat-sealable resin layer). For Example 2, the pressure-sensitive adhesive layer was cut and removed, assuming that it would be cut off and removed after sealing in the manufacturing process of the energy storage device. More specifically, a 15mm wide strip of test material in the MD direction was cut 5mm from the fold to remove the area containing the 4.5mm pressure-sensitive adhesive layer located on the fold side. The resulting test material was then measured in accordance with JIS K7127:1999, and the seal strength in the measurement environment at opening temperature A was measured as follows.Using a tensile testing machine with a constant temperature chamber, the seal strength (N / 15mm) between the resin film and the heat-sealable resin layer at opening temperature A was measured at a speed of 300 mm / min by chucking one outer packaging material against the opposite outer packaging material at a peel angle of 180° (chuck distance of 50 mm). The measurement results are shown in Table 1.

[0232] (Measurement procedure for seal strength A at opening temperature A determined by opening tests: Resin film of Example 7) In Example 7, the resin film for energy storage devices was used as the heat-sealable resin layer for the exterior material of the energy storage device. Specifically, a biaxially oriented PET film (thickness 12 μm) and a biaxially oriented nylon film (thickness 15 μm) were laminated in this order as base layers by dry lamination. On top of this, a barrier layer made of aluminum foil (JIS H4160:1994 A8021H-O, thickness 40 μm) with acid-resistant coatings formed on both sides was laminated by dry lamination. Specifically, a two-component curing urethane adhesive (polyol compound and aromatic isocyanate compound) was applied to one side of the PET film to form an adhesive layer (thickness 3 μm after curing) on ​​the PET film. Next, the biaxially oriented nylon film was laminated. Next, a two-component curing urethane adhesive (polyol compound and aromatic isocyanate compound) was applied to one side of the aluminum foil with acid-resistant coatings formed on both sides to form an adhesive layer (thickness 3 μm after curing) on ​​the aluminum foil. Next, an adhesive layer on aluminum foil and a PET film / nylon film laminate were laminated with the nylon film facing the aluminum foil, and then an aging treatment was performed to create a laminate of a base layer / adhesive layer / barrier layer. Then, a two-component curing urethane adhesive (polyol compound and aromatic isocyanate compound) was applied to the barrier layer side of the obtained laminate to form an adhesive layer (3 μm thick after curing) on ​​the aluminum foil. Furthermore, a resin film for energy storage devices was laminated on top of the adhesive layer as a heat-sealable resin layer by dry lamination. Next, the resulting laminate was aged and heated to obtain an exterior material for an energy storage device, in which PET (12 μm) / DL (3 μm) / ONY (15 μm) / DL (3 μm) / ALM (40 μm) / DL (3 μm) / random PP (135°C, 5 μm) / LLDPE (100°C, 40 μm) / random PP (135°C, 5 μm) / partially provided pressure-sensitive adhesive layer (primer layer 10 μm) were laminated in this order.

[0233] Next, the obtained exterior material for the energy storage device was cut to a size of MD150mm × TD60mm. With the heat-sealable resin layer of the exterior material for the energy storage device facing inward, it was folded in half at the center position in the MD direction (75mm position), and the opposing heat-sealable resin layers (resin films) were heat-sealed using a heel sealing machine with 7mm wide upper and lower metal heads at a temperature of 190°C, a surface pressure of 0.5MPa, and for 3 seconds to obtain a laminate. The sealing position was a 7mm wide strip extending in the MD direction, from a position 5mm below the fold to a position 12mm below. At this time, the heat-sealable resin layers of the exterior material for the energy storage device, that is, the opposing resin films, were heat-sealed to each other. The obtained laminate was cut, and a strip-shaped test piece with a width of 15mm in the MD direction was obtained from the central part. The seal strength of the obtained test piece was measured in accordance with the provisions of JIS K7127:1999, under the measurement environment of opening temperature A, as follows. Using a tensile testing machine with a constant temperature chamber, the seal strength (N / 15mm) of the heat-sealable resin layers, which are resin films, at opening temperature A was measured at a speed of 300 mm / min by chucking one outer packaging material against the opposite outer packaging material and pulling them at a peel angle of 180° (chuck distance of 50 mm). Note that if the test specimen is pulled immediately after being placed in the constant temperature chamber at opening temperature A, the temperature will not be constant, so the measurement was taken 1 minute after the test specimen reached opening temperature A. The test specimen temperature was measured by attaching a thermocouple to the test specimen. The results are shown in Table 1.

[0234] (Measurement procedure for seal strength A at opening temperature A determined by opening tests: Resin film of Example 8) In Example 8, one sheet of the exterior material for the energy storage device used in the above-mentioned (measurement procedure for seal strength A at opening temperature A determined by the opening test: resin film of Examples 1-6) was cut to a size of 360 mm in the MD direction and 180 mm in the TD direction. The heat-sealable resin layer of the exterior material for the energy storage device was wrapped around a dummy cell (aluminum metal block) measuring 100 mm in length, 140 mm in width, and 30 mm in thickness, which mimicked an electrode body, so that it faced the block side. One lid 60 (100 mm in length, 5 mm in width, and 30 mm in thickness, polypropylene, melting peak temperature 140°C) was placed at each of the openings at both ends of the wrapped exterior material for the energy storage device. At this time, the resin film (15 mm x 30 mm) from Example 8, with the release PET removed, was sandwiched between one of the lids 60 and the exterior material for the energy storage device. After wrapping the lid 60 and dummy cell with tension applied, the parts where the exterior materials for the energy storage device face each other were heat-sealed using a dedicated machine for wrapping and sealing at a temperature of 220°C, a pressure of 1.0 MPa, and for 5 seconds, with a metal sealing bar on the upper side and silicone rubber on the lower side. Subsequently, the contact edge between the lid 60 and the exterior material for the energy storage device (the overlapping portion of the 5 mm wide peripheral surface of the lid and the exterior material for the energy storage device, which covers the lid when the exterior material for the energy storage device is wrapped around it) was heat-sealed at a temperature of 180°C, a pressure of 1.8 MPa, and for 3 seconds, to obtain a test sample in which the exterior of the energy storage device includes the exterior material for the energy storage device and the lid, and is interposed between the exterior material for the energy storage device and the lid. At this time, the resin film was placed so that the pressure-sensitive adhesive layer was located at the 1.5 mm end of the 5 mm wide seal width of the lid, opposite to the energy storage device element (in this case, an aluminum metal block simulating an electrode body), and then heat-sealed to create a test sample.

[0235] A cut was made in the test sample along the long side of the lid (MD direction of the outer casing material) using a cutter, and the dummy cell that had been placed inside was removed. A 15 mm wide cut was made in the outer casing material for the energy storage device at the position where the resin film was sealed, and a test specimen was obtained in which the outer casing material for the energy storage device / resin film was 15 mm wide and sealed to the lid. The seal strength of the obtained test specimen was measured in accordance with the provisions of JIS K7127:1999 at the measurement environment of opening temperature A as follows: Using a tensile testing machine with a constant temperature chamber, at the measurement environment of opening temperature A, one side of the outer casing material and the opposite lid were chucked and pulled at a peel angle of 180° (chuck distance 50 mm), and the seal strength (N / 15 mm) between the outer casing material for the energy storage device / resin film / lid at opening temperature A was measured at a speed of 300 mm / min. The results are shown in Table 1.

[0236] (Measurement procedure for seal strength A at opening temperature A determined by opening tests: Resin film of Example 9) In Example 9, one sheet of the exterior material for the energy storage device used in the above-mentioned (measurement procedure for seal strength A at opening temperature A determined by the opening test: resin film of Examples 1-6) was cut to a size of 360 mm in the MD direction and 180 mm in the TD direction. Furthermore, a lid body 60 was prepared by insert molding a 1 mm thick polypropylene (melting peak temperature 140°C) coating 61 onto the periphery of the lid body 62 (98 mm long x 5 mm wide x 28 mm thick, aluminum material). At this time, the resin film from Example 9, which had been cut to a size of 30 mm MD x 15 mm TD and had its release PET peeled off, was placed on one of the longitudinal sides of the lid body 62 and injection molded so that it was sandwiched between the lid body 62 and the coating 61. At this time, a resin film was placed on the lid body 62 such that the end opposite to the energy storage device element with the pressure-sensitive adhesive layer was positioned relative to the lid body 62, and injection molded to create a lid in which the resin film was interposed between the lid body and the covering. Similar to the measurement of the seal strength with resin film in Example 8, a dummy cell was prepared, and the exterior material for the energy storage device was wrapped around this dummy cell and the obtained lid. The portions where the heat-fusible resin layers of the exterior material for the energy storage device faced each other were heat-sealed using a dedicated machine for wrapping and sealing at a temperature of 220°C, a pressure of 1.0 MPa, and for 5 seconds, with a metal sealing bar on the upper side and silicone rubber on the lower side. Subsequently, the lid body 60 and the exterior material for the energy storage device were heat-sealed at a temperature of 200°C, a pressure of 1.8 MPa, and for 3 seconds, to obtain a test sample in which the exterior body of the energy storage device included the exterior material for the energy storage device and the lid, and the lid included a lid body and a covering that covers the periphery of the lid body, with the covering interposed between the lid body and the covering.

[0237] A cut was made with a cutter along the long side direction of the lid material (MD direction of the exterior material) on the test sample, and the dummy cell placed inside was taken out. A cut was made with a width of 15 mm in the exterior material for the power storage device at the position including the resin film installation position, and a test piece in a state where the exterior material for the power storage device / resin film had a width of 15 mm and was sealed to the lid was obtained. Regarding the obtained test piece, in accordance with the provisions of JIS K7127:1999, the seal strength in the measurement environment of the unsealing temperature A was measured as follows. Using a tensile testing machine equipped with a thermostatic bath, in the measurement environment of the unsealing temperature A, at a speed of 300 mm / min, one exterior material and the facing lid were chucked and pulled at a peeling angle of 180° (the distance between the chucks was 50 mm), and the seal strength (N / 15 mm) at each temperature between the exterior material for the power storage device / resin film / lid was measured. The results are shown in Table 1.

[0238]

Table 1

[0239] As described above, the present disclosure provides an invention in the following aspects. Item 1. A resin film for a power storage device, The resin film for the power storage device is composed of a laminate including at least a base film and a pressure-sensitive adhesive layer, The pressure-sensitive adhesive layer constitutes at least one surface of the resin film for the power storage device, The pressure-sensitive adhesive layer is partially provided on the base film, a resin film for a power storage device. Item 2. The resin film for a power storage device according to Item 1, wherein the ratio of the area of the portion where the pressure-sensitive adhesive layer is laminated to the area of one side of the base film is 50% or less. Item 3. The resin film for a power storage device according to Item 1 or 2, wherein the pressure-sensitive adhesive layer is provided at one end of one side of the base film. Item 4. The resin film for a power storage device according to any one of Items 1 to 3, wherein the pressure-sensitive adhesive layer is provided in a pattern on the base film. Item 5. The resin film for a power storage device according to any one of Items 1 to 4, which contains at least one selected from the group consisting of a polyolefin, an acid-modified polyolefin, a polyester, and a polyamide. Item 6. The resin film for a power storage device according to any one of Items 1 to 5, wherein the base film is single-layer or multi-layer. Item 7. The resin film for a power storage device according to any one of Items 1 to 6, which contains at least one resin layer having a melting peak temperature of 80°C or higher and 240°C or lower. Item 8. The resin film for a power storage device according to any one of Items 1 to 7, which contains at least one resin layer having a melting peak temperature of 80°C or higher and 160°C or lower. Item 9. The resin film for a power storage device according to any one of Items 1 to 8, which is used for any one of the following uses 1) to 4). 1) A use in which it is used so as to be interposed between heat-sealable resin layers of an exterior material for a power storage device at a position where the heat-sealable resin layers are heat-sealed to each other. <I 2) A use in which it is used as a heat-sealable resin layer of an exterior material for a power storage device. 3) A use in which the exterior body of a power storage device includes an exterior material for a power storage device and a lid body, and it is used so as to be interposed between the exterior material for a power storage device and the lid body. 4) The exterior body of a power storage device includes an exterior material for a power storage device and a lid body. The lid body includes a lid main body and a covering body that covers the periphery of the lid main body. A use in which it is used so as to be interposed between the lid main body and the covering body. Item 10. The resin film for a power storage device according to Item 9, which contains at least one resin layer having a melting peak temperature lower than that of the heat-sealable resin layer of the exterior material for a power storage device in the use of 1), 2), or 3). Item 11. The resin film for a power storage device according to any one of Items 1 to 10, which has a characteristic that the seal strength A (N / 15 mm) at an unsealing temperature A determined by the following unsealing test is 50 N / 15 mm or less. <Measurement conditions for seal strength A at opening temperature A> The opening temperature A used when measuring seal strength A is determined by performing the following opening test. (Opening test) Prepare one casing material for an energy storage device (8cm wide x 19cm high) with a total thickness of 153μm, consisting of the following layers: base layer (PET (12μm thick) / adhesive (3μm thick) / nylon (15μm thick)) / adhesive layer (3μm thick) / barrier layer (aluminum alloy foil, 40μm thick) / adhesive layer (maleic anhydride modified polypropylene, 40μm thick) / heat-sealable resin layer (polypropylene, peak melting temperature 140℃, 40μm thick). Fold the casing material in half so that the heat-sealable resin layer is on the inside, and make a φ11mm hole in one place on one side (exactly in the center of the 8cm wide x 9.5cm high rectangle). Attach a jig at the location of the hole for installing a tube to supply air into the sample during the opening test. Next, place the energy storage device resin fill between the heat-sealable resin layers on the short side (horizontal). The size of the resin film for the energy storage device shall be 3 cm wide x 1.5 cm high. The exterior material for the energy storage device and the resin film for the energy storage device shall be positioned so that their widths and heights match. More specifically, horizontally, the centers of the exterior material and the resin film for the energy storage device shall be aligned, and vertically, the short side of the resin film for the energy storage device, which is 3 cm long, shall be aligned with the short side of the resin film for the energy storage device, which is the short side of the resin film for the energy storage device, which is the short side of the resin film for the energy storage device, which is the short side of the resin film for the energy storage device, and the two long sides of the exterior material for the energy storage device shall be heat-sealed under the conditions of a pressure of 0.5 MPa, a temperature of 190°C, 3 seconds, and a seal width of 7 mm, to create a test sample. At this time, both sides of the resin film for the energy storage device shall be heat-sealed to the heat-sealable resin layer. A thermocouple is attached to the test sample and placed inside the oven. A φ5 mm tube is attached to a tube mounting jig, and air is blown into the test sample through the attached tube. The internal pressure is maintained at 0.1 MPa once it reaches a constant pressure. The test sample is heated from room temperature (25°C) at a heating rate of 6°C / min until it reaches 150°C. The opening temperature of the test sample when it is opened is defined as temperature A (°C).

[0240] (Measurement of seal strength A at opening temperature A determined in the opening test) An exterior material for energy storage devices with a total thickness of 153 μm is prepared, consisting of a base layer (PET (thickness 12 μm) / adhesive (thickness 3 μm) / nylon (thickness 15 μm)) / adhesive layer (thickness 3 μm) / barrier layer (aluminum alloy foil, thickness 40 μm) / adhesive layer (maleic anhydride modified polypropylene, thickness 40 μm) / heat-sealable resin layer (polypropylene, melting peak temperature 140°C, thickness 40 μm) laminated in this order, and cut to a size of 60 mm (width in the Z direction) x 150 mm (length in the X direction). The exterior material for energy storage devices is folded in half with the heat-sealable resin layer facing inward, and a resin film for energy storage devices (30 mm in the Z direction, 15 mm in the X direction) is sandwiched between the two halves. In this state, the laminate is obtained by heat sealing with a sealing machine with 7 mm wide upper and lower metal heads at 190°C x 0.5 MPa x 3 seconds. The resulting laminate is cut, and a 15mm strip-shaped test piece (with both sides of the adhesive film heat-sealed to the heat-sealable resin layer of the energy storage device's exterior material) is obtained from the center of the position where the resin film for the energy storage device is sandwiched between the heat-sealable resin layers of the energy storage device's exterior material. The seal strength of the obtained test piece is measured in accordance with the provisions of JIS K7127:1999, at temperatures A (opening temperature) and B (opening temperature -20°C), respectively, as follows: Using a tensile testing machine with a constant temperature chamber, one exterior material and the opposite exterior material are chucked at a speed of 300mm / min and pulled at a peeling angle of 180° (chuck distance is 50mm), and the seal strength (N / 15mm) at each temperature is measured. 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 by an outer casing, An energy storage device comprising a resin film for energy storage devices described in any one of items 1 to 11 in at least one of the following embodiments: 1) to 4). 1) An embodiment in which the heat-fusible resin layers of the exterior material for an energy storage device are interposed between the heat-fusible resin layers at the position where they are heat-fussed together. 2) Embodiments included as a heat-fusible resin layer for exterior material of energy storage device 3) An embodiment in which the exterior of the energy storage device includes an exterior material for the energy storage device and a lid, and is interposed between the exterior material for the energy storage device and the lid. 4) The casing of the energy storage device includes an casing material for the energy storage device and a cover. The lid comprises a lid body and a covering that covers the periphery of the lid body. an embodiment that is interposed between the lid body and the covering. Item 13. A method for manufacturing an energy storage device, wherein an energy storage device element comprising at least a positive electrode, a negative electrode, and an electrolyte is housed in a package formed by an outer casing, A method for manufacturing an energy storage device, comprising at least one of the following steps 1) to 4). 1) Arrange the resin film for energy storage devices described in any one of items 1 to 11 so as to be interposed between the heat-sealable resin layers of the exterior material for energy storage devices at a position where the heat-sealable resin layers of the exterior material for energy storage devices are heat-sealed together. The process involves fixing the pressure-sensitive adhesive layer of the resin film for the energy storage device to the surface of the heat-sealable resin layer, and then heat-sealing the heat-sealable resin layers together with the resin film for the energy storage device in between. 2) Using a resin film for energy storage devices described in any one of items 1 to 11 as a heat-sealable resin layer for an exterior material for energy storage devices, A step of fixing the pressure-sensitive adhesive layer present on the surface of the heat-fusible resin layer on one side of the exterior material for the energy storage device to the surface of the heat-fusible resin layer on the other side of the exterior material for the energy storage device, and then heat-fusing the heat-fusible resin layers together. 3) The exterior of the energy storage device includes an exterior material for the energy storage device and a cover. A step of fixing the pressure-sensitive adhesive layer of the resin film for energy storage devices described in any one of items 1 to 11 to the exterior material for the energy storage device or the lid, and then heat-sealing the exterior material for the energy storage device and the lid with the resin film for the energy storage device interposed between them. 4) The casing of the energy storage device includes an casing material for the energy storage device and a cover. The lid comprises a lid body and a covering that covers the periphery of the lid body. A step of fixing the resin film for energy storage devices described in any one of items 1 to 11 to the lid body or the covering body, and then heat-sealing the lid body and the covering body with the resin film for energy storage devices interposed between them. Item 14. The method for manufacturing an energy storage device according to Item 13, further comprising the step of removing at least a portion of the portion of the resin film for the energy storage device on which the pressure-sensitive adhesive layer is formed, in steps 1) and 2) above. [Explanation of Symbols]

[0241] 1. Resin film for energy storage devices 2 metal terminals 3. Exterior materials for energy storage devices 3a Peripheral edge of exterior material 4 Energy Storage Device Elements 5. Adhesive film for metal terminals 10 Energy Storage Devices 11. Base film 12 Pressure-sensitive adhesive layer 30 Exterior 31 Base material layer 32 Adhesive layer 33 Barrier layer 34 Adhesive layer 35 Heat-fusible resin layer 60 Lid 61 Covering 62 Lid body 70 Heat-sealed joint between heat-sealable resin layers

Claims

1. A resin film for energy storage devices, The resin film for the energy storage device is composed of a laminate including at least a base film and a pressure-sensitive adhesive layer. The pressure-sensitive adhesive layer constitutes at least one surface of the resin film for the energy storage device, The pressure-sensitive adhesive layer is partially provided on the base film, The proportion of the area of ​​one side of the base film to which the pressure-sensitive adhesive layer is laminated is 50% or less. The pressure-sensitive adhesive layer is provided at one end of the base film, The pressure-sensitive adhesive layer is provided in a pattern on the base film, A resin film for energy storage devices, comprising at least one resin layer having a peak melting temperature of 80°C or higher and 240°C or lower.

2. The resin film for energy storage devices according to claim 1, wherein the resin film for energy storage devices comprises at least one selected from the group consisting of polyolefin, acid-modified polyolefin, polyester, and polyamide.

3. The resin film for energy storage devices according to claim 1 or 2, wherein the base film is single-layer or multi-layer.

4. A resin film for an energy storage device according to claim 1 or 2, comprising at least one resin layer having a melting peak temperature of 80°C or higher and 160°C or lower.

5. The resin film for energy storage devices according to claim 1 or 2, wherein the resin film for energy storage devices is used for any of the following applications 1) to 4). 1) Applications in which the heat-sealable resin layers of the exterior material for energy storage devices are interposed between the heat-sealable resin layers at the location where they are heat-sealed together. 2) Applications as a heat-sealable resin layer for exterior materials of energy storage devices 3) Applications in which the exterior of a power storage device includes an exterior material for the power storage device and a lid, and is used so as to be interposed between the exterior material for the power storage device and the lid. 4) The exterior of the energy storage device includes an exterior material for the energy storage device and a cover. The lid comprises a lid body and a covering that covers the periphery of the lid body. Applications in which it is interposed between the lid body and the covering

6. The resin film for an energy storage device according to claim 5, wherein, in the application of 1), 2), or 3), it includes at least one resin layer with a lower melting peak temperature than the heat-sealable resin layer of the exterior material for the energy storage device.

7. A resin film for energy storage devices according to claim 1 or 2, having the characteristic that the seal strength A (N / 15 mm) at the opening temperature A determined by the following opening test is 50 N / 15 mm or less. <Measurement conditions for seal strength A at opening temperature A> The opening temperature A used when measuring seal strength A is determined by performing the following opening test. (Opening test) Prepare one casing material for an energy storage device (8 cm wide x 19 cm long) with a total thickness of 153 μm, consisting of the following layers: base layer (PET (12 μm thick) / adhesive (3 μm thick) / nylon (15 μm thick)) / adhesive layer (3 μm thick) / barrier layer (aluminum alloy foil, 40 μm thick) / adhesive layer (maleic anhydride modified polypropylene, 40 μm thick) / heat-sealable resin layer (polypropylene, peak melting temperature 140°C, 40 μm thick). Fold the casing material in half so that the heat-sealable resin layer is on the inside, and make a φ11 mm hole in one place on one side (exactly in the center of the 8 cm wide x 9.5 cm long rectangle). Attach a jig at the location of the hole for installing a tube to supply air into the sample during the opening test. Next, place the resin film for the energy storage device between the heat-sealable resin layers on the short side (horizontal). The size of the resin film for the energy storage device shall be 3 cm wide x 1.5 cm high. The exterior material for the energy storage device and the resin film for the energy storage device shall be positioned so that their widths and heights coincide. More specifically, horizontally, the centers of the exterior material and the resin film for the energy storage device shall coincide, and vertically, the short side of the resin film for the energy storage device, which is 3 cm long, shall align with the short side of the exterior material, which is 8 cm long, which is the bottom vertical edge of the exterior material. Next, the short side on which the resin film for the energy storage device is positioned and the two long sides of the exterior material for the energy storage device shall be heat-sealed under the conditions of a pressure of 0.5 MPa, a temperature of 190°C, 3 seconds, and a seal width of 7 mm, to create a test sample. At this time, both sides of the resin film for the energy storage device shall be heat-sealed to the heat-sealable resin layer. A thermocouple is attached to the test sample and placed in the oven. A φ5 mm tube is attached to the tube mounting jig, and air is blown into the test sample through the attached tube. The internal pressure is maintained at a constant level of 0.1 MPa. The test sample is heated from room temperature (25°C) at a heating rate of 6°C / min until it reaches 150°C. The opening temperature of the test sample when it is opened is defined as temperature A (°C). (Measurement of seal strength A at opening temperature A determined in the opening test) An exterior material for energy storage devices with a total thickness of 153 μm is prepared, consisting of a base layer (PET (thickness 12 μm) / adhesive (thickness 3 μm) / nylon (thickness 15 μm)) / adhesive layer (thickness 3 μm) / barrier layer (aluminum alloy foil, thickness 40 μm) / adhesive layer (maleic anhydride modified polypropylene, thickness 40 μm) / heat-sealable resin layer (polypropylene, melting peak temperature 140°C, thickness 40 μm) laminated in this order, and cut to a size of 60 mm horizontally (Z direction) x 150 mm vertically (X direction). The exterior material for energy storage devices is folded in half with the heat-sealable resin layer facing inward, and a resin film for energy storage devices (horizontal (Z direction) x vertical (X direction) 15 mm) is sandwiched in between. In this state, the laminate is obtained by heat sealing with a sealing machine with 7 mm wide upper and lower metal heads at 190°C x 0.5 MPa x 3 seconds. The resulting laminate is cut, and a 15 mm strip-shaped test piece (with both sides of the adhesive film heat-sealed to the heat-sealable resin layer of the energy storage device's exterior material) is obtained from the center of the position where the resin film for the energy storage device is sandwiched between the heat-sealable resin layers of the energy storage device's exterior material. For the obtained test piece, the seal strength in environments of temperature A (opening temperature) and temperature B (opening temperature - 20°C) is measured as follows, in accordance with the provisions of JIS K7127:1999. Using a tensile testing machine with a constant temperature chamber, one exterior material and the opposite exterior material are chucked at a speed of 300 mm / min and pulled at a peeling angle of 180° (chuck distance is 50 mm), and the seal strength (N / 15 mm) at each temperature is measured.

8. An energy storage device in which an energy storage device element comprising at least a positive electrode, a negative electrode, and an electrolyte is housed in a package formed by an outer casing, An energy storage device comprising a resin film for energy storage devices as described in claim 1 or 2 in at least one of the following embodiments: 1) to 4). 1) An embodiment in which the heat-sealable resin layers of the exterior material for an energy storage device are interposed between the heat-sealable resin layers at the location where they are heat-sealed together. 2) Embodiments included as a heat-sealable resin layer for an exterior material for an energy storage device 3) An embodiment in which the exterior of the energy storage device includes an exterior material for the energy storage device and a lid, and is interposed between the exterior material for the energy storage device and the lid. 4) The exterior of the energy storage device includes an exterior material for the energy storage device and a cover. The lid comprises a lid body and a covering that covers the periphery of the lid body. an embodiment that is interposed between the lid body and the covering.

9. A method for manufacturing an energy storage device, wherein an energy storage device element comprising at least a positive electrode, a negative electrode, and an electrolyte is housed in a package formed by an outer casing, A method for manufacturing an energy storage device, comprising at least one of the following steps 1) to 4). 1) The resin film for energy storage devices according to claim 1 or 2 is placed between the heat-sealable resin layers at a position where the heat-sealable resin layers of the exterior material for energy storage devices are heat-sealed together, The process involves fixing the pressure-sensitive adhesive layer of the resin film for the energy storage device to the surface of the heat-sealable resin layer, and then heat-sealing the heat-sealable resin layers together with the resin film for the energy storage device in between. 2) Using the resin film for energy storage devices described in claim 1 or 2 as a heat-sealable resin layer for the exterior material of an energy storage device, A step of fixing the pressure-sensitive adhesive layer present on the surface of the heat-fusible resin layer on one side of the exterior material for the energy storage device to the surface of the heat-fusible resin layer on the other side of the exterior material for the energy storage device, and then heat-fusing the heat-fusible resin layers together. 3) The exterior of the energy storage device includes an exterior material for the energy storage device and a cover. A step of fixing the pressure-sensitive adhesive layer of the resin film for the energy storage device according to claim 1 or 2 to the exterior material for the energy storage device or the lid, and then heat-sealing the exterior material for the energy storage device and the lid with the resin film for the energy storage device interposed between them. 4) The exterior of the energy storage device includes an exterior material for the energy storage device and a cover. The lid comprises a lid body and a covering that covers the periphery of the lid body. A step of fixing the resin film for the energy storage device according to claim 1 or 2 to the lid body or the covering, and then heat-sealing the lid body and the covering with the resin film for the energy storage device interposed between them.

10. The method for manufacturing an energy storage device according to claim 9, further comprising the step of removing at least a portion of the portion of the resin film for the energy storage device on which the pressure-sensitive adhesive layer is formed, in steps 1) and 2) above.

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