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

Abstract

Provided is an exterior material for a power storage device, the exterior material exhibiting excellent moldability and adherence with an adhesive.　The present invention pertains to an exterior material for a power storage device, the exterior material comprising: a barrier layer 4 made from a metal foil; a heat-resistant layer 2 made from a heat-resistant resin and provided on an outer surface side of the barrier layer 4; and a thermal fusion layer 3 made from a thermal fusion resin and provided on an inner surface side of the barrier layer 4. An easily-sliding layer 5 including an anionic surfactant is provided on an outer surface side of the heat-resistant layer 2, and the amount of the easily-sliding layer 5 that is present is set to 1.0 mg / m2 to 10.0 mg / m2, inclusive.

Description

[Technical Field]

[0001] This invention relates to an outer casing material for energy storage devices such as lithium secondary batteries (lithium-ion batteries, lithium polymer batteries, etc.), lithium-ion capacitors, and electric double-layer capacitors, as well as a method for manufacturing the same, and to energy storage devices including all-solid-state batteries. [Background technology]

[0002] In recent years, with the miniaturization and weight reduction of mobile electronic devices such as smartphones and tablet terminals, laminates consisting of a heat-resistant resin layer (heat-resistant layer), adhesive layer, metal foil layer (barrier layer), adhesive layer, and thermoplastic resin layer (heat-sealed layer) have been used as the exterior material for energy storage devices such as lithium-ion secondary batteries, lithium polymer secondary batteries, lithium-ion capacitors, and electric double-layer capacitors, instead of conventional metal cans (Patent Documents 1-3). Furthermore, power supplies for electric vehicles, large power supplies for energy storage, and capacitors are increasingly being enclosed in laminates (exterior materials) with the above configuration. When forming exterior materials for energy storage devices, the laminate is molded into a three-dimensional shape such as a roughly rectangular parallelepiped by processes such as stretch molding or deep drawing. By molding into such a three-dimensional shape, it is possible to secure a housing space for the main body of the energy storage device.

[0003] In order to deeply draw and mold the exterior material, it is preferable to reduce the friction between the outer layer surface (heat-resistant layer surface) and the inner layer surface (heat-sealed layer surface) to improve lubricity.

[0004] For example, conventionally, a lubricant such as a fatty acid amide was added to the film constituting the heat-sealing layer (heat-sealing layer film), and the lubricant was bleed out to obtain the lubricity of the inner layer surface. Furthermore, the lubricity of the outer layer surface was obtained by transferring the lubricant of the heat-sealing layer to the outer layer surface during the aging treatment while the exterior material was wound up.

[0005] On the other hand, conventional methods have been employed to obtain lubricity on the outer surface of the outer layer of the packaging material, such as directly applying lubricants like fatty acid amides or slippery resins, or laminating slippery resin layers. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Patent No. 4736188 [Patent Document 2] Patent No. 4940496 [Patent Document 3] Japanese Patent Publication No. 2020-91990 [Overview of the project] [Problems that the invention aims to solve]

[0007] However, in the method of adding a lubricant such as a fatty acid amide to the inner layer (heat-sealed layer) described above, the amount of lubricant transferred to the outer layer is affected by temperature and pressure, making it difficult to obtain uniform lubricity across the entire surface of the outer layer, and thus making it difficult to obtain stable and good moldability.

[0008] Furthermore, in methods where lubricants are applied to the surface of the outer layer, the total amount of lubricant applied to the outer layer and the lubricant added to the inner layer can be large, making it difficult to accurately control the amount of lubricant and thus making it difficult to obtain good moldability.

[0009] Furthermore, in methods of laminating a slippery resin layer, the binder resin constituting the slippery resin layer is required to have various properties such as heat resistance, solvent resistance, wettability, and printability. Therefore, selecting a resin that satisfies all of these properties has been difficult in the present day.

[0010] On the other hand, it is conceivable to impart lubricity to the exterior material using a surfactant. However, since surfactants possess release properties, problems arise in terms of adhesion. That is, energy storage devices enclosed in an exterior material are often housed in a case together with other electronic circuits, and in this case, adhesive tapes such as protective tape or mounting tape are applied to the outer surface of the battery exterior material to secure the energy storage device to the other electronic circuits. Therefore, if lubricity is simply imparted using a surfactant, the problem arises that sufficient adhesion of the tape to the outer surface of the exterior material cannot be obtained (the adhesive tape peels off easily).

[0011] Preferred embodiments of the present invention have been made in view of the aforementioned and / or other problems in the related art. Preferred embodiments of the present invention can significantly improve upon existing methods and / or apparatus.

[0012] This invention has been made in view of the above-mentioned problems, and aims to provide an exterior material for an energy storage device, a method for manufacturing the same, and an energy storage device that can improve moldability while also ensuring sufficient adhesion to adhesives such as tapes.

[0013] Other objectives and advantages of the present invention will become apparent from the following preferred embodiments. [Means for solving the problem]

[0014] To solve the above problems, the present invention comprises the following means.

[0015] [1] An exterior material for an energy storage device comprising a barrier layer made of metal foil, a heat-resistant layer made of heat-resistant resin provided on the outer surface side of the barrier layer, and a heat-sealable layer made of heat-sealable resin provided on the inner surface side of the barrier layer, A slippery layer containing an anionic surfactant is provided on the outer surface side of the heat-resistant layer. The amount of the slippery layer present is 1.0 mg / m 2 ~10.0 mg / m² 2 An exterior material for energy storage devices characterized by being set to a specific configuration.

[0016] [2] The outer packaging material for a power storage device according to item 1 above, wherein the coefficient of kinetic friction on the outer surface of the slippery layer is set to 0.05 to 0.3 according to JIS K7125 (1999).

[0017] [3] The outer packaging material for a power storage device according to item 1 or 2 above, wherein the heat-sealing layer is composed of a polypropylene resin containing a lubricant.

[0018] [4] The outer packaging material for a power storage device according to any one of items 1 to 3 above, wherein the heat-resistant layer is composed of a multilayer structure including a first layer made of a polyamide-based resin and a second layer made of a polyester-based resin provided on the outer surface side of the first layer.

[0019] [5] A method for manufacturing an outer packaging material for a power storage device, including a barrier layer made of a metal foil, a heat-resistant layer made of a heat-resistant resin provided on the outer surface side of the barrier layer, and a heat-sealing layer made of a heat-sealing resin provided on the inner surface side of the barrier layer, wherein a slippery layer with a coating amount of 1.0 mg / m 2 ~10.0 mg / m 2 is formed by applying an anionic surfactant to the outer surface side of the heat-resistant layer. The method for manufacturing an outer packaging material for a power storage device is characterized by including this step.

[0020] [6] A power storage device body, and the outer packaging material according to any one of claims 1 to 4, characterized in that the power storage device body is packaged with the outer packaging material.

Advantages of the Invention

[0021] According to the exterior material for energy storage devices of the invention [1], a slippery layer containing an anionic surfactant is provided as the outermost layer on the surface of the outer layer, thereby achieving the desired slipperiness and improving moldability. Furthermore, since the slippery layer is formed in a specific amount, excessive slipperiness (release properties) beyond what is necessary can be suppressed, sufficient adhesion to adhesives such as adhesive tapes can be ensured, and problems such as peeling of adhesive tapes can be reliably prevented. Moreover, since the anionic surfactant of the present invention has superior dispersibility compared to cationic and nonionic surfactants, a surfactant film (slippery layer) can be formed without gaps over the entire surface of the outer layer, and in this respect as well, sufficient adhesion can be obtained while ensuring good slipperiness.

[0022] According to the exterior material for energy storage devices of the invention [2], the coefficient of dynamic friction of the smooth surface is specified, so the above effects can be obtained more reliably.

[0023] According to the exterior material for energy storage devices of the invention [3], since the heat-sealable layer, which is the inner layer, contains a lubricant, the lubricant is transferred to the slippery layer, and the lubricating effect of the lubricant, combined with the lubricating effect of the surfactant in the slippery layer, can reliably impart the desired slipperiness to the surface of the outermost layer.

[0024] According to the exterior material for energy storage devices of the invention [4], since it is composed of a multilayer structure including an inner polyamide resin layer and an outer polyester resin layer, anionic surfactants as a lubricating layer are easily dispersed on the surface of the outer polyester resin layer, and the lubricating layer can be reliably formed over the entire surface of the outer layer. Furthermore, since a polyamide resin layer with excellent moldability is arranged on the inside, it also has excellent moldability.

[0025] According to the method for manufacturing an exterior material for an energy storage device of the invention [5], an anionic surfactant is applied to the outer surface to form a slippery layer, so the amount of slippery layer applied and, consequently, the film thickness can be freely controlled, and the desired slipperiness can be imparted more reliably.

[0026] According to the invention [6], a high-quality energy storage device with reliable operation can be provided because it is equipped with the exterior material of the invention [1] which has excellent moldability and adhesion. [Brief explanation of the drawing]

[0027] [Figure 1] Figure 1 is a cross-sectional view showing an exterior material for an energy storage device, which is an embodiment of this invention. [Figure 2] Figure 2 is a schematic diagram illustrating the coating state of the surfactant in the exterior material for the energy storage device of the embodiment, where Figure (a) is a cross-sectional view and Figure (b) is a plan view. [Figure 3] Figure 3 is a cross-sectional view showing an energy storage device manufactured using the exterior material of the embodiment. [Figure 4] Figure 4 is a perspective view showing an exploded view of the energy storage device of the embodiment. [Modes for carrying out the invention]

[0028] Figure 1 is a cross-sectional view showing an exterior material for an energy storage device that is an embodiment of the present invention. As shown in the figure, this exterior material 1 for an energy storage device includes a heat-resistant layer 2 made of heat-resistant resin as an outer layer, a heat-sealable layer (sealant layer) 3 made of heat-sealable resin as an inner layer, and a barrier layer 4 as a metal foil layer (intermediate layer) disposed between these two layers 2 and 3, with a smooth-slip layer 5 formed on the outer surface of the heat-resistant layer 2 as the outermost layer.

[0029] The barrier layer 4 can be made of metal foil consisting of aluminum (Al) foil, copper (Cu) foil, stainless steel (SUS) foil, nickel (Ni) foil, or titanium (Ti) foil, and in particular, 1000 series or 8000 series Al foil as specified in JIS H4160 can be preferably used. In this embodiment, the terms aluminum, copper, nickel, and titanium are used to include their alloys as well.

[0030] The thickness of the barrier layer 4 is preferably set to 20 μm to 100 μm, and more preferably to 30 μm to 80 μm.

[0031] Furthermore, it is preferable to apply a chemical conversion treatment to at least the inner surface (the surface facing the heat-sealed layer 3) of the barrier layer 4. This chemical conversion treatment effectively prevents corrosion of the barrier layer surface by the contents (such as the electrolyte of the battery).

[0032] The heat-resistant layer 2 can preferably be made of a heat-resistant resin such as polyester resins like biaxially oriented nylon film (ONy), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), polyethylene furanoate (PEF), or biaxially oriented polypropylene (OPP).

[0033] Furthermore, as the heat-resistant resin, it is preferable to use a thermoplastic resin with a temperature of 10°C or higher for the heat-fusible resin constituting the heat-fusible layer 3, and more preferably a thermoplastic resin with a temperature of 20°C or higher.

[0034] The heat-resistant layer 2 can be formed, for example, by bonding a resin film constituting the heat-resistant layer 2 to one side (outer surface) of the barrier layer (metal foil) 5 via an adhesive. The heat-resistant layer 2 may be composed of a single layer, or it may be composed of a multi-layer structure, for example, a structure in which two or more resin films are laminated.

[0035] When the heat-resistant layer 2 is constructed as a single layer, it is preferable to use a polyester resin film such as PET. Furthermore, in the case of a single-layer structure, since the anionic surfactant is water-based, a film with a low water absorption rate, such as polyethylene terephthalate (PET) film, can exert its effect with a smaller amount than a film with a high water absorption rate, such as biaxially oriented nylon (ONy) film. In other words, in the case of ONy film, the surfactant is absorbed into the film, so the coefficient of dynamic friction may increase if the same amount of coating is used as with PET film.

[0036] Furthermore, in the case of a two-layer structure, it is preferable to use a composite film that combines a polyester film and a polyamide film such as nylon. In addition, in the case of a two-layer structure, it is preferable to adopt a structure in which a polyamide film is laminated on the outer surface of the barrier layer 4, and a polyester film is laminated on the upper surface (outer surface) of the polyamide film, that is, a structure in which the polyester is positioned on the outside of the polyamide.

[0037] The thickness of the heat-resistant layer 2 should be set to 10 μm to 50 μm, whether it is a single-layer or multi-layer structure.

[0038] Furthermore, urethane-based adhesives, epoxy-based adhesives, and acrylic-based adhesives can be suitably used as adhesives for bonding the resin film for the heat-resistant layer 2 to the barrier layer 4. The thickness of this adhesive should ideally be set to 1 μm to 5 μm.

[0039] The heat-sealable layer 3 can preferably be made of a heat-sealable resin (thermoplastic resin) such as unoriented polypropylene (CPP) or polyethylene, with CPP being particularly preferred.

[0040] The heat-sealable layer 3 can be formed, for example, by bonding a resin film constituting the heat-sealable layer 3 to the other side (inner surface) of the barrier layer 4 via an adhesive. The heat-sealable layer 3 may be composed of a single layer or a multilayer structure. The thickness of the heat-sealable layer 3 is preferably set to 20 μm to 100 μm.

[0041] In this embodiment, the resin constituting the heat-sealable layer 3 contains a lubricant in an amount of 100 ppm to 2000 ppm.

[0042] Fatty acid bisamides (amides) such as saturated fatty acid amides, unsaturated fatty acid amides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, and aromatic bisamides can be suitably used as lubricants.

[0043] Specifically, examples of saturated fatty acid amides include lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, and hydroxystearic acid amide.

[0044] Examples of the above-mentioned unsaturated fatty acid amides include oleic acid amide and erucic acid amide.

[0045] Examples of the saturated fatty acid bisamides mentioned above include methylenebisstearamide, ethylenebiscaprate, ethylenebislaurate, ethylenebisstearamide, ethylenebishydroxystearamide, ethylenebisbehenamide, hexamethylenebisstearamide, hexamethylenebisbehenamide, hexamethylenehydroxystearamide, N,N'-distearyladipamide, and N,N'-distearylsebacinamide.

[0046] Examples of the above-mentioned unsaturated fatty acid bisamides include ethylenebisoleamide, ethylenebiserucamide, hexamethylenebisoleamide, N,N'-dioleyladipamide, and N,N'-dioleylsebacinamide.

[0047] Examples of the above-mentioned aromatic bisamides include m-xylylenebisstearate, m-xylylenebishydroxystearate, and N,N'-distearyl isophthalamide.

[0048] Furthermore, when bonding the resin film for the heat-sealable layer 3 to the barrier layer 4, dry lamination using olefin-based adhesives, epoxy-based adhesives, and especially acid-modified olefin-based adhesives, or heat lamination using olefin-based or acid-modified olefin-based thermoplastic resins can be used.

[0049] For dry lamination, the adhesive thickness should be set to 1 μm to 5 μm, while for heat lamination, the thickness of the thermoplastic resin used as the adhesive should be set to 5 μm to 10 μm.

[0050] In this embodiment, the slippery layer (outermost layer) 5 is composed of an anionic surfactant.

[0051] Suitable anionic surfactants include sulfonates such as carboxylates (soaps), sulfates, phosphates, palmitates, metal oleates, alkylnaphthalene sulfons, sulfur oxides of butyl oleates, octyl sulfate, cetyl sulfate, lauryl sulfate, and other C8-C18 organic sulfates, as well as organic sulfonates such as stearates, octyl sulfons, cetyl sulfons, lauryl sulfons, stearyl sulfons, oleyl sulfons, p-toluenesulfons, dodecylbenzenesulfons, oleylbenzenesulfons, naphthyl sulfons, and diisopropylnaphthylsulfons. Note that "salt" refers to a metal salt.

[0052] In this embodiment, a specific example of an anionic surfactant is "Elecut XC301-A," a product manufactured by Takemoto Oil & Fat Co., Ltd.

[0053] The smooth-slip layer 5 is formed by dissolving the above-mentioned anionic surfactant in a solvent such as water or alcohol (solution for the smooth-slip layer), coating the outer surface of the heat-resistant layer 2 with the solution, and then drying it to remove the solvent.

[0054] Here, because anionic surfactants have excellent dispersibility in solvents such as water and alcohol, the anionic surfactant is evenly distributed throughout the entire surface of the lubrication solution without bias. As a result, as shown in Figures 2(a) and 2(b), the lubrication layer 5, which is an anionic surfactant, can be formed without gaps (without any uncoated areas) on the entire surface of the heat-resistant layer 2 that constitutes the exterior material 1. For example, as shown in Figure 2(a), even if there are irregularities on the surface of the heat-resistant layer 2, the lubrication layer 5 can be applied thickly to the recesses and thinly to the protrusions, thereby allowing the lubrication layer 5 to be applied to the entire surface of the heat-resistant layer 2 regardless of its surface condition. Note that in Figure 2(a), the irregular shape of the heat-resistant layer 2 is exaggerated to facilitate understanding of the invention.

[0055] Furthermore, unsaturated long-chain fatty acid salts such as anionic surfactants are appropriately dispersed, making it easier for surface protrusions (roughnesses) to form, and good activity can be imparted even with a small amount of application. However, if the application is excessive, the release properties become too strong, so in order to ensure a balance between release properties and activity, it is preferable to use sodium oleate as the anionic surfactant.

[0056] In this embodiment, the amount of coating (dry component) after solvent removal in the smooth layer 5 is 1.0 mg / m². 2 ~10.0 mg / m² 2 It is preferable to set the amount to [amount]. In other words, if the amount of coating is too small, the slippery layer 5 cannot be formed without gaps over the entire outer surface of the heat-resistant layer 2, making it difficult to reliably obtain the desired slipperiness and potentially leading to a decrease in moldability, which is undesirable. Conversely, if the amount of coating is too large, the release properties may become excessively apparent, potentially reducing adhesion to the adhesive tape, which is also undesirable.

[0057] In this embodiment, the exterior material 1 is subjected to heat aging treatment while wound into a roll shape, with the heat-sealing layer 3 facing inward and the smooth-slip layer 5 (heat-resistant layer 2) facing outward. During this process, the lubricant contained in the heat-sealing layer 3 precipitates from the surface (inner side) of the heat-sealing layer 3 and is transferred to the smooth-slip layer 5 (heat-resistant layer 2), which is the outermost layer, thereby imparting an appropriate amount of lubricant to the smooth-slip layer 5 and the heat-resistant layer 2. Therefore, the transferred lubricant, combined with the lubricity of the smooth-slip layer 5 itself, makes it possible to obtain the desired lubricity on the outer surface of the exterior material 1.

[0058] In this embodiment, the anionic surfactant used as the lubricating layer 5 contains only the transferred lubricant, and there is a possibility that other substances, such as the solvent used during the coating of the lubricating layer solution, may remain. The lubricating layer 5 does not contain any fine particles such as antiblocking material (AB material).

[0059] The exterior material 1 for the energy storage device of this embodiment, configured as described above, is used as an exterior case for an energy storage device, either in sheet form or, if necessary, molded into a predetermined shape by thermoforming such as deep drawing or stretch molding.

[0060] For example, Figures 3 and 4 are a cross-sectional view and an exploded perspective view showing a power storage device 30 manufactured using the exterior material 1 of this embodiment. As shown in both figures, this power storage device 30 is a lithium-ion secondary battery. In this embodiment, the exterior case 15 is composed of a tray member 14 obtained by molding the exterior material 1 and a lid member 10 made of a flat (sheet-shaped) exterior material 1. A power storage device body (electrochemical element, etc.) 31 in a substantially rectangular parallelepiped shape is housed in a housing recess of the tray member 14 obtained by molding the exterior material 1 of the present invention, and the lid member 10 (exterior material 1) of the present invention is placed on the power storage device body 31 with its heat-sealed layer 3 side facing inward (downward). The outer peripheral edge of the heat-sealed layer 3 of the lid member 10 and the heat-sealed layer 3 of the flange portion (sealing peripheral edge portion) 29 of the tray member 14 are sealed by heat sealing, thereby forming the power storage device 30. Furthermore, the inner surface of the receiving recess of the tray member 14 is made of a heat-sealing layer 3, and the outer surface of the receiving recess is on the side of the slip-resistant layer 5 (heat-resistant layer 2) (see Figure 4).

[0061] In Figure 3, the symbol "39" represents the heat-sealed portion where the outer peripheral edge of the lid member 10 and the flange portion (sealing peripheral edge) 29 of the tray member 14 are joined (welded). In the energy storage device 30, the tip of the tab lead connected to the main body 31 of the energy storage device is led out to the outside of the outer case 15, but this is not shown in the illustration.

[0062] The main body 31 of the energy storage device is not particularly limited, but examples include a battery body, a capacitor body, a capacitor body, etc.

[0063] In the above embodiment, the outer case 15 is composed of a tray member 14 obtained by molding the outer material 1 and a flat lid member 10. However, the present invention is not limited to such a combination. For example, the outer case 15 may be composed of a pair of flat (sheet-shaped) outer materials 1, or it may be composed of a pair of tray members 14 stacked facing each other.

[0064] As described above, according to the exterior material 1 of this embodiment, a smooth-slip layer 5 is formed on the outer surface to obtain sufficient lubricity, and the heat-sealable layer 3 as the inner layer also obtains sufficient lubricity due to the lubricant, thus reliably improving moldability.

[0065] In particular, since the slip-free layer 5 is provided without gaps across the entire outer surface of the exterior material 1, the desired slipperiness can be reliably obtained, and moldability can be reliably improved. In this embodiment, the coefficient of dynamic friction of the outer surface of the slip-free layer 5 is set to 0.05 to 0.3. As described above, good slipperiness can be obtained, and sufficient moldability can be reliably obtained.

[0066] In this embodiment, the coefficient of dynamic friction was measured in accordance with JIS K7125 (1999).

[0067] Furthermore, the amount of the smooth-slip layer 5 applied is 1.0 mg / m². 2 ~10.0 mg / m² 2 Because it is set to be thin and evenly formed over the entire outer surface, it is possible to suppress the occurrence of excessive slipperiness and excessive release properties. As a result, sufficient adhesion to the adhesive of the adhesive tape can be ensured on the outer surface (easy-slip layer 5) of the exterior material 1, and problems such as peeling of the adhesive tape can be reliably prevented. Furthermore, since the coefficient of dynamic friction of the easy-slip layer 5 is 0.05 or higher, adhesion to the adhesive tape can be more reliably ensured in this respect as well.

[0068] Furthermore, in this embodiment, since the slippery layer 5 is formed by coating the outer surface of the heat-resistant layer 2 with a slippery layer solution, the amount of slippery layer 5 applied and, consequently, the film thickness can be freely controlled compared to cases where the slippery layer is formed by transfer from the heat-sealing layer 3 or by elution from the heat-resistant layer 2. This ensures that the desired slipperiness is reliably provided, further improving the quality and reliability of the exterior material 1.

[0069] In addition, in the present embodiment, when the heat-resistant layer 2 is configured by a two-layer structure including an inner polyamide resin layer (first layer) and an outer polyester resin layer (second layer), since the outer polyester resin layer is likely to be charged negatively, it can be presumed that an anionic surfactant is likely to be dispersed (difficult to aggregate) on its surface. It is considered that a film (slip layer 5) made of an anionic surfactant can be uniformly formed over the entire outer surface, and desired slipperiness can be more surely imparted.

Example

[0070]

Table 1

[0071] <Example 1> On both sides of an aluminum foil (A8021-O) with a thickness of 40 μm as the barrier layer 4, a chemical conversion treatment solution composed of phosphoric acid, polyacrylic acid (acrylic resin), chromium (III) salt compound, water, and alcohol was applied, and then dried at 180°C to form a chemical conversion film. The chromium adhesion amount of this chemical conversion film was 10 mg / m per side. 2 It was as follows.

[0072] Next, as shown in Table 1, a heat-resistant layer 2 was formed in a two-layer structure on one surface (outer surface) of the chemically converted aluminum foil (barrier layer 4). That is, on one surface (outer surface) of the aluminum foil (barrier layer 4), a biaxially stretched 6 nylon (ONy) film with a thickness of 15 μm was dry-laminated and bonded as the first layer of the heat-resistant layer 2 through a two-component curable urethane-based adhesive (thickness 3 μm). Further, on the upper surface (outer surface) of the biaxially stretched 6 nylon (ONy) film, a stretched polyethylene terephthalate (PET) film with a thickness of 12 μm was dry-laminated and bonded as the second layer of the heat-resistant layer 2 through a two-component curable urethane-based adhesive (thickness 3 μm). Thereby, a base film in which the heat-resistant layer 2 was laminated on the upper surface (outer surface) of the barrier layer 4 was produced.

[0073] Next, a solution (solution for the smooth layer) made by adding sodium oleate (indicated as "anionic surfactant A" in Table 1) to isopropyl alcohol (IPA) onto the base film was applied to the surface of the film constituting the outer layer of the base film (heat-resistant layer 2), and then dried at 150°C to form the smooth layer 5 on the heat-resistant layer 2. The amount of smooth layer 5 applied after drying was 2.5 mg / m² as shown in Table 1. 2 That is the case.

[0074] Next, a 40 μm thick unoriented polypropylene (CPP) film was superimposed on the other side (inner surface) of the aluminum foil (barrier layer 4) of the base film via a two-component curing maleic acid-modified polypropylene adhesive (2 μm thick). This film was then dry-laminated by sandwiching it between a rubber nip roll and a laminating roll heated to 100°C and pressing it together to obtain a laminate for exterior materials. The laminate was then wound onto a roll shaft and aged at 40°C for 10 days to obtain a sample of exterior material 1 of Example 1.

[0075] The method for measuring the amount of the slip-free layer 5 shown in Table 1 involves preparing a test piece by cutting the exterior material 1 to a size of 10 cm x 10 cm, and measuring the weight of the test piece using a precision balance (minimum display of 1 μg). The weight at that time (weight before wiping) is defined as "W0" mg.

[0076] Next, the heat-resistant layer surface of the test specimen was wiped with cotton soaked in ethanol, and after the specimen was thoroughly dried, its weight was measured using a precision balance. This weight (weight after wiping) was designated as "W1" mg. The amount of coating was then calculated using the relationship "(W1-WO)×100=coating amount".

[0077] <Examples 2-4> As shown in Table 1, the amount of slip-free layer 5 applied is "1 mg / m²". 2 "6.5 mg / m²" 2 "10mg / m²" 2 Samples of exterior material 1 for Examples 2 to 4 were obtained in the same manner as in Example 1, except that the setting was changed to ".

[0078] <Example 5> As shown in Table 1, a sample of exterior material 1 for Example 5 was obtained in the same manner as in Example 1, except that sodium sulfate ester (labeled "Anionic surfactant B" in Table 1) was used as the anionic surfactant.

[0079] <Example 6> As shown in Table 1, a sample of the exterior material 1 for Example 6 was obtained in the same manner as in Example 1, except that the heat-resistant layer 2 was composed of a single layer of biaxially oriented nylon 6 (ONy) film with a thickness of 25 μm.

[0080] <Example 7> As shown in Table 1, a sample of the exterior material 1 of Example 7 was obtained in the same manner as in Example 1, except that the heat-resistant layer 2 was composed of a single layer of stretched polyethylene terephthalate (PET) film with a thickness of 12 μm.

[0081] <Example 8> As shown in Table 1, an anionic surfactant B is used for the smooth layer 5, and the amount of smooth layer 5 applied is "1 mg / m²". 2 A sample of exterior material 1 for Example 8 was obtained in the same manner as in Example 1, except that it was set to ".

[0082] <Example 9> As shown in Table 1, sodium stearyl sulfonate (labeled "Anionic Surfactant C" in Table 1) was used as the anionic surfactant, and the amount of lubrication layer 5 applied was 4.5 mg / m². 2 A sample of exterior material 1 for Example 9 was obtained in the same manner as in Example 1, except that it was set to ".

[0083] <Comparative Example 1>

[0084] [Table 2]

[0085] As shown in Table 2, a sample of the exterior material 1 of Comparative Example 1 was obtained in the same manner as in Example 1, without forming the slippery layer 5.

[0086] <Comparative Example 2> As shown in Table 2, a sample of exterior material 1 for Comparative Example 2 was obtained in the same manner as in Example 1, except that a cationic surfactant was used instead of an anionic surfactant to form the outermost layer (corresponding to the slippery layer).

[0087] <Comparative Example 3> As shown in Table 2, a sample of exterior material 1 for Comparative Example 3 was obtained in the same manner as in Example 1, except that a nonionic surfactant was used instead of an anionic surfactant to form the outermost layer (corresponding to the slippery layer).

[0088] <Comparative Example 4> As shown in Table 2, an amide-based lubricant (fatty acid amide) was applied using isopropyl alcohol (IPA) as a solvent, and the IPA was dried at 150°C to form the outermost layer (corresponding to the slippery layer) on the outer surface of the heat-resistant layer 2, thereby forming the outermost layer. In addition, a sample of the exterior material 1 for Comparative Example 4 was obtained in the same manner as in Example 1.

[0089] <Comparative Examples 5, 6> As shown in Table 2, the amount of slip-free layer 5 applied is "0.5 mg / m² 2 "12mg / m²" 2 Samples of exterior material 1 for Comparative Examples 5 and 6 were obtained in the same manner as in Example 1, except that the setting was changed to ''.

[0090] <Coefficient of Dynamic Friction> In each of the exterior materials in the examples and comparative examples, the coefficient of dynamic friction of the outermost surface (the surface of the heat-resistant layer in Comparative Example 1) was measured in accordance with JIS K7125 (1999), as described in the above embodiment. The results are shown in Tables 1 and 2.

[0091] <Tape Peelability Test> Test specimens measuring 15 mm in width and 150 mm in length were cut from each of the exterior materials 1 of the examples and comparative examples. Adhesive tape with an adhesive strength of 13 N / cm (product name "tesa 70415") was applied to the surface of each test specimen along its length. The width of the adhesive tape was 5 mm, and its length was 80 mm or more. A hand roll weighing 2 kgf was then run back and forth five times over this adhesive tape, and the specimens were left to stand at room temperature for one hour.

[0092] Next, a Shimadzu Strograph (AGS-5kNX) tensile testing machine was used. One chuck was used to clamp and fix the end of the test specimen, while the other chuck was used to grip the end of the adhesive tape. Then, in accordance with JIS K6854-3 (1999), the peel strength was measured when the tape was peeled 180° at a peeling speed of 300 mm / min. The value at which this measurement stabilized was defined as the adhesion force (unit: N / 5mm) between the outermost layer of the adhesive tape and the surface of the tape.

[0093] Furthermore, as evaluation criteria for the adhesion between the outermost surface of the heat-resistant resin layer and the adhesive tape, an adhesion force of 6N / 5mm or more was marked as "◎ (very high)", 5N / 5mm or more but less than 6N / 5mm was marked as "○ (high)", and less than 5N / 5mm was marked as "× (low)". The results are shown in Tables 1 and 2.

[0094] <Moldability Test> Test pieces measuring 100 mm x 100 mm were cut from each of the exterior materials 1 of the examples and comparative examples. For each test piece, a deep drawing test was performed using a deep drawing die attached to a 25t press, with the drawing height (drawing depth) varied in 0.5 mm increments.

[0095] Furthermore, if the required moldability was achieved even when the molding height was 8 mm or more, it was evaluated as "◎"; if the required moldability was not achieved in the range of 6 mm or more and less than 8 mm, it was evaluated as "〇"; and if the required moldability was not achieved in less than 6 mm, it was evaluated as "×". The results are shown in Tables 1 and 2.

[0096] <Visual inspection (white powder test)> A 600mm long piece of packaging material (test specimen) was cut from each of the exterior materials 1 of the examples and comparative examples in the MD direction.

[0097] On the other hand, a weight made of stainless steel (SUS), weighing 1.3 kg and measuring 55 mm x 50 mm, was wrapped with Kimwipes, and then a green cloth (black) was wrapped around it to prepare a weighted green cloth.

[0098] Then, the weighted green cloth was placed on the outermost surface of the test specimen and pulled at a length of 400 mm, a speed of 4 cm / s, and at an angle horizontal to the bottom surface. The green cloth used was TRUSCO's static electricity removal sheet S SD2525 3100.

[0099] After contacting the outermost surface of the test specimen using the method described above, the surface (contact surface) of the clean cloth was visually observed and evaluated as follows: "×" for significant white powder formation, "〇" for moderate white powder formation, and "◎" for no white powder or almost no white powder formation. The results are shown in Tables 1 and 2.

[0100] <Overall assessment> As shown in Table 1, the exterior material 1 of Examples 1 to 9 related to the present invention received good evaluations in all aspects, including tape adhesion, moldability, and white powder generation. In particular, the exterior material 1 of Examples 1 to 7, in which the dynamic friction coefficient was adjusted to the range of 0.05 to 0.3, received even better evaluations.

[0101] Furthermore, Example 1 exhibited superior moldability compared to Examples 6 and 7. This is because Example 1 has a multilayer structure of PET film and ONy film for its heat-resistant layer, while Examples 6 and 7 have a single-layer structure of ONy film or PET film, resulting in higher moldability as a base material.

[0102] On the other hand, as shown in Table 2, the exterior materials of Comparative Examples 1 to 6, which deviate from the gist of the present invention, were inferior in at least one of the evaluations.

[0103] This application is accompanied by a priority claim from Japanese Patent Application No. 2021-114008, filed on July 9, 2021, and the disclosures thereof constitute a part of this application.

[0104] The terms and expressions used herein are for illustrative purposes only and not intended to be restrictive, and should be understood as not excluding any equivalents of the features shown and described herein, and allowing for various modifications within the claimed scope of this invention. [Industrial applicability]

[0105] The exterior material for energy storage devices of this invention can be suitably used when manufacturing energy storage devices such as batteries and capacitors used in portable devices such as smartphones and tablets, and batteries and capacitors used in hybrid vehicles, electric vehicles, wind power generation, solar power generation, and for storing nighttime electricity. [Explanation of Symbols]

[0106] 1: Exterior materials 2: Heat resistant layer 3: Heat-sealed layer 4: Barrier layer 5: Easy slip layer 10: Lid component (exterior material) 14: Tray components (exterior materials) 15: Outer case (outer material) 30: Energy storage devices 31: Device body

Claims

1. An exterior material for an energy storage device comprising a barrier layer made of metal foil, a heat-resistant layer made of heat-resistant resin provided on the outer surface side of the barrier layer, and a heat-sealable layer made of heat-sealable resin provided on the inner surface side of the barrier layer, A coating containing an anionic surfactant is provided on the outer surface of the heat-resistant layer. The amount of the slippery layer present is 1.0 mg / m ２ ~10.0 mg / m² ２ It is set to, The heat-sealing layer contains a lubricant, An exterior material for an energy storage device, characterized in that the lubricant contained in the heat-sealing layer is attached to the surface of the coating of the easy-slip layer.

2. The exterior material for an energy storage device according to claim 1, wherein the coefficient of dynamic friction on the outer surface of the slippery layer is set to 0.05 to 0.3 according to JIS K7125 (1999).

3. The exterior material for an energy storage device according to claim 1 or 2, wherein the heat-sealable layer is composed of a polypropylene resin containing a lubricant.

4. The heat-resistant layer is configured by a multilayer structure comprising a first layer made of polyamide resin and a second layer made of polyester resin provided on the outer surface side of the first layer, as described in any one of claims 1 to 3.

5. A method for manufacturing an exterior material for an energy storage device, comprising a barrier layer made of metal foil, a heat-resistant layer made of heat-resistant resin provided on the outer surface side of the barrier layer, and a heat-sealable layer made of heat-sealable resin provided on the inner surface side of the barrier layer, After coating the outer surface of the heat-resistant layer with a solution of an anionic surfactant dissolved in a solvent, the solvent is removed by drying, resulting in a coating amount of 1.0 mg / m². ２ ~10.0 mg / m² ２ A method for manufacturing an exterior material for an energy storage device, characterized by including a step of forming a slippery layer.

6. The main body of the energy storage device, The exterior material is as described in any one of claims 1 to 4, An energy storage device characterized in that the main body of the energy storage device is enclosed with the exterior material.

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