Exterior material for a battery storage device and a battery storage device using the same

Abstract

An outer casing for a capacitor device related to one aspect of the present disclosure has a laminated structure comprising, in this order, a substrate layer, a first adhesive layer, a metal foil layer, a second adhesive layer, and an inner layer comprising a polyester resin. The inner layer has a melting peak temperature at melting measured by a differential scanning calorimeter in the range of 160 to 280 °C. The substrate layer has a melting peak temperature higher than the melting peak temperature of the inner layer.

Description

Technology Field

[0001] The present disclosure relates to an exterior material for a battery storage device and a battery storage device using the same. Background Technology

[0002] As energy storage devices, secondary batteries such as lithium-ion batteries, nickel-hydrogen batteries, and lead-acid batteries, as well as electrochemical capacitors such as electric double-layer capacitors, are known. Due to the miniaturization of portable devices and limitations on installation space, further miniaturization of energy storage devices is required, and lithium-ion batteries with high energy density are attracting attention. Conventionally, metal cans were used as casing materials for lithium-ion batteries, but multilayer films are now being used because they are lightweight, have high heat dissipation, and can be manufactured at low cost.

[0003] A lithium-ion battery using the above-mentioned multilayer film as an outer casing is referred to as a laminated lithium-ion battery. The outer casing covers the battery contents (positive electrode, separator, negative electrode, electrolyte, etc.) and prevents the intrusion of moisture into the interior. A laminated lithium-ion battery is manufactured, for example, by forming a concave portion in a part of the outer casing by cold forming, accommodating the battery contents within the concave portion, folding back the remaining part of the outer casing, and sealing the edge portion with a heat seal (for example, see Patent Document 1). Prior art literature

[0004] Japanese Patent Publication No. 2013-101765 The problem to be solved

[0005] However, research and development of a storage device referred to as an all-solid-state battery is being carried out as a next-generation battery for lithium-ion batteries. All-solid-state batteries are characterized by using a solid electrolyte instead of an organic electrolyte as the electrolyte material. While lithium-ion batteries cannot be used at temperatures higher than the boiling point of the electrolyte (about 80°C), all-solid-state batteries can be used at temperatures exceeding 100°C, and the conductivity of lithium ions can be increased by operating them under high temperature conditions (e.g., 100 to 150°C).

[0006] However, when using a laminated structure as described above as an exterior material and manufacturing a laminated all-solid-state battery, there is a concern that the sealing performance of the all-solid-state battery package may be insufficient due to the insufficient heat resistance of the exterior material. Furthermore, the inventors have sought to improve the heat resistance of the exterior material and have discovered that depending on the combination of the substrate layer (outer layer) and the inner layer (layer having heat sealing properties) in the exterior material having a laminated structure, the appearance of the storage device (especially the heat seal part) deteriorates.

[0007] The present disclosure has been made in consideration of the above-mentioned problem and provides an exterior material that is useful for manufacturing a capacitor with an excellent appearance and also has excellent heat resistance, and a capacitor using the same. means of solving the problem

[0008] One aspect of the present disclosure provides an outer casing for a storage device. The outer casing has a laminated structure comprising, in this order, a substrate layer, a first adhesive layer, a metal foil layer, a second adhesive layer, and an inner layer comprising a polyester resin, wherein the inner layer has a melting peak temperature at melting measured by differential scanning calorimetry (DSC) in the range of 160 to 280°C, and the substrate layer has a melting peak temperature higher than the melting peak temperature of the inner layer. Specific examples of the polyester resin include polyethylene terephthalate (PET) and its copolymer, and a polyester resin based on a component of PET.

[0009] The sealant layer (inner layer) of conventional exterior materials for energy storage devices is mainly composed of polypropylene-based resin and has a melting point of about 130 to 150°C. For this reason, the heat resistance is insufficient for use in all-solid-state batteries, for example, which can reach temperatures of 100 to 150°C. On the other hand, the exterior material related to the present disclosure employs an inner layer containing polyester-based resin and having a melting peak temperature in the range of 160 to 280°C, thereby making it applicable in terms of heat resistance to energy storage devices capable of reaching such temperatures. Furthermore, by having a base layer with a melting peak temperature higher than that of the inner layer, it is possible to suppress the deterioration of the appearance caused by the melting of the base layer (outer layer) during heat sealing. In addition, the “melting peak temperature” referred to here can be obtained in accordance with the method described in JIS K7121-1987, and if two or more melting peaks appear independently, the lowest melting peak temperature is adopted.

[0010] An all-solid-state battery may be used as a storage device to which the exterior material related to the present disclosure can be applied. However, it is not limited to this, and the exterior material may be applied to other storage devices (e.g., lithium-ion secondary batteries).

[0011] The inner layer of the exterior material related to the present disclosure may be a single-layer structure or a multi-layer structure. When the inner layer is a single-layer structure, the inner layer may be, for example, a crystalline PET film (melting peak temperature: about 255°C), or a PET or copolymer film in which a portion thereof is amorphized so that the melting peak temperature is lowered to, for example, a range of 160 to 250°C. A film with a lowered melting peak temperature may be a film of a polyester resin based on a PET component. Such a polyester resin has structural units derived from ethylene glycol, structural units derived from terephthalic acid, and other structural units. Examples of dihydric alcohol components from which the structural units of this polyester resin originate include neopentyl glycol, 1,4-butadiol, diethylene glycol, etc. Examples of acid components from which the structural units of this polyester resin originate include isophthalic acid, adipic acid, sebacic acid, etc. By adjusting the amount of these structural units, the melting point of the polyester resin can be adjusted. Hereinafter, the above polyester resin based on PET copolymers and PET components is referred to as PET-based resin.

[0012] When the inner layer has a multilayer structure, the inner layer may be configured to have a first layer containing a polyester resin and having a melting peak temperature of 170 to 280°C, and a second layer formed on the inner surface of the first layer and containing a polyester resin, wherein the second layer has a melting peak temperature in the range of 160 to 270°C and is lower than the melting peak temperature of the first layer. By employing a second layer that melts more easily than the first layer, even better seal strength can be achieved. From the perspective of achieving even better seal strength and heat resistance, a layer containing a thermosetting resin may be employed as the second layer.

[0013] In the case where the inner layer is a multilayer structure comprising the first and second layers, a third layer may be additionally provided on the surface opposite to the side where the second layer is formed in the first layer. The third layer may be configured to include a polyester resin and have a melting peak temperature in the range of 160 to 270°C, which is lower than the melting peak temperature of the first layer. By employing a third layer that melts more easily than the first layer, even better seal strength can be achieved. From the perspective of achieving even better seal strength and heat resistance, a layer comprising a thermosetting resin may be employed as the third layer.

[0014] One aspect of the present disclosure provides a storage device (e.g., an all-solid-state battery) comprising a storage device body, a current extraction terminal extending from the storage device body, and an outer casing that clamps the current extraction terminal and also accommodates the storage device body. Effects of the invention

[0015] According to the present disclosure, an outer material that is useful for manufacturing a capacitor with an excellent appearance and also has excellent heat resistance, and a capacitor using the same are provided. Brief explanation of the drawing

[0016] FIG. 1 is a perspective view showing an all-solid-state battery, which is an embodiment of a storage device related to the present disclosure. FIG. 2 is a cross-sectional view schematically showing one embodiment of an exterior material. FIGS. 3(a) to FIGS. 3(c) are cross-sectional views schematically showing the composition of the inner layer. FIG. 4 is a cross-sectional view along line IV-IV shown in FIG. 1, schematically illustrating the configuration of a tab (resin film for terminals and metal terminals) of an all-solid-state battery. FIGS. 5(a) to FIGS. 5(c) are cross-sectional views schematically showing the composition of a resin film for a terminal. Specific details for implementing the invention

[0017] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In addition, identical or substantial parts in the drawings are denoted by the same reference numerals, and redundant descriptions are omitted. Also, the dimensional ratios in the drawings are not limited to the ratios depicted.

[0018] <Electric storage device>

[0019] FIG. 1 is a perspective view showing the schematic configuration of a storage device related to the present embodiment. In FIG. 1, an all-solid-state battery is illustrated as an example of a storage device (100), and the following description is provided. Additionally, the storage device with the configuration shown in FIG. 1 may be referred to as a battery pack or a battery cell.

[0020] The energy storage device (100) is an all-solid-state battery and comprises an energy storage device body (10), an exterior material (20), a pair of metal terminals (30) (current extraction terminals), and a resin film (40) for terminals (tab sealant). The energy storage device body (10) is a battery body that performs charging and discharging. The exterior material (20) is arranged to cover the surface of the energy storage device body (10) and to come into contact with a part of the resin film (40) for terminals.

[0021] (Exterior materials)

[0022] FIG. 2 is a cross-sectional view showing an example of a cross-sectional view of an exterior material (20). The exterior material (20) has a multilayer structure having a substrate layer (11), a first adhesive layer (12a), a first corrosion-resistant treatment layer (13a), a barrier layer (metal foil layer) (15), a second corrosion-resistant treatment layer (13b), a second adhesive layer (12b), and an inner layer (18) in this order, extending from the outside toward the inside (side of the capacitor body (10)). The inner layer (18) comprises polyethylene terephthalate (PET) or a copolymer thereof and has a melting peak temperature in the range of 160 to 280°C. The substrate layer (11) has a melting peak temperature higher than the melting peak temperature of the inner layer (18).

[0023] By having an inner layer (18) that includes PET or a copolymer thereof and has a melting peak temperature in the range of 160 to 280°C, the outer material (20) can achieve the heat resistance required for an outer material of a storage device (100) (all-solid-state battery) used under temperature conditions of, for example, 100 to 150°C. In addition, by having a base layer (11) that has a melting peak temperature higher than that of the inner layer (18), the deterioration of the appearance caused by the melting of the base layer (11) (outer layer) during heat sealing can be suppressed. Below, first, the inner layer (18) and the base layer (11) will be described.

[0024] For the inner layer (18), a commercially available crystalline PET film (melting peak temperature: about 255°C) may be used. Depending on the heat resistance required for the inner layer (18) (such as the operating temperature conditions of the capacitor (100)), the melting peak temperature of the inner layer (18) may be adjusted within the above range. For example, the degree of crystallization of the crystalline PET film may be adjusted, it may be made unstretched, it may be made into a copolymer containing units of polyethylene terephthalate and units of other resins, or a PET film containing crystalline PET and amorphous PET may be used. Alternatively, a polyester resin based on the components of PET may be used as the material for the inner layer (18). Such a polyester resin has structural units derived from ethylene glycol, structural units derived from terephthalic acid, and other structural units. Examples of dihydric alcohol components from which the structural units of this polyester resin originate include neopentyl glycol, 1,4-butadiol, diethylene glycol, etc. Examples of acid components from which the structural units of this polyester resin originate include isophthalic acid, adipic acid, sebacic acid, etc. By adjusting the amount of these structural units, the melting point of the polyester resin can be adjusted. Hereinafter, the above polyester resin based on PET copolymers and PET components is referred to as a PET-based resin.

[0025] The melting peak temperature of the inner layer (18) is in the range of 160 to 280 ℃, as described above. If this temperature is less than 160 ℃, the heat resistance of the inner layer (18) becomes insufficient, and if it exceeds 280 ℃, the temperature required for the heat seal becomes excessively high. The lower limit of the melting peak temperature of the inner layer (18) may be 175 ℃, 185 ℃, 195 ℃, 200 ℃, 215 ℃, 215 ℃, 225 ℃, or 235 ℃. The upper limit of the melting peak temperature of the inner layer (18) may be 275 ℃, 268 ℃, 262 ℃, or 252 ℃.

[0026] The inner layer (18) may be a single-layer structure or a multi-layer structure. As shown in FIG. 3(a), when the inner layer (18) is a single-layer structure, the inner layer (18) may be, for example, a crystalline PET film (melting peak temperature: about 255°C), or the degree of crystallization of the crystalline PET film may be adjusted, or it may be non-stretched, or a PET-based resin may be used to lower the melting peak temperature to, for example, a range of 160 to 250°C. In addition, when a PET film with a lowered melting peak temperature is used as the inner layer (18), it is possible to use a crystalline PET film (melting peak temperature: about 255°C) as the substrate layer (11).

[0027] When the inner layer (18) is a single-layer structure, the thickness of the inner layer (18) is preferably 10 to 100 μm, and more preferably 20 to 80 μm. By having a thickness of 10 μm or more, it is easy to secure sealing and insulation properties, while by having a thickness of 100 μm or less, it is possible to achieve cost reduction.

[0028] As shown in FIG. 3(b), the inner layer (18) may have a two-layer structure having a first layer (18a) and a second layer (18b) formed on the inner surface of the first layer (18a). The first layer (18a) preferably comprises PET and / or a PET-based resin and has a melting peak temperature of 170 to 280 °C. The second layer (18b) preferably comprises PET and / or a PET-based resin and has a melting peak temperature lower than the melting peak temperature of the first layer (18a). The melting peak temperature of the second layer (18b) may be, for example, in the range of 160 to 270 °C. The melting peak temperature T of the first layer (18a) A and the melting peak temperature T of the second layer (18b) B The difference of (T A- T B The temperature is preferably 10°C or higher, and more preferably 20 to 100°C. By having this temperature difference of 10°C or higher, even better seal strength can be achieved.

[0029] The thickness of the first layer (18a) is preferably 5 to 500 μm, and more preferably 20 to 200 μm. It is easy to ensure insulation when the thickness of the first layer (18a) is 5 μm or more, while it is possible to achieve cost reduction when it is 500 μm or less.

[0030] The second layer (18b) may include a thermosetting resin instead of PET or PET-based resin in terms of heat resistance and seal strength, or it may include both PET or PET-based resin and a thermosetting resin. Examples of thermosetting resins include polyimide resin, phenolic resin, urea resin, melamine resin, unsaturated polyester resin, urethane resin, allyl resin, epoxy resin, furan resin, and silicone resin. Among these, one type may be used alone, or two or more types may be used in combination.

[0031] The thickness of the second layer (18b) is preferably 5 to 500 μm, and more preferably 20 to 200 μm. It is easy to ensure sealing properties when the thickness of the second layer (18b) is 5 μm or more, while it is possible to achieve cost reduction when it is 500 μm or less.

[0032] As shown in FIG. 3(c), the inner layer (18) may have a three-layer structure having a first layer (18a), a second layer (18b), and a third layer (18c) formed on the surface opposite to the side where the second layer (18b) is formed in the first layer (18a). The third layer (18c) preferably comprises PET and / or a PET-based resin and has a melting peak temperature lower than the melting peak temperature of the first layer (18a). The melting peak temperature of the third layer (18c) may be, for example, in the range of 160 to 270°C. The melting peak temperature T of the first layer (18a) A and the melting peak temperature T of the third layer (18c) C The difference of (T A - T C The temperature is preferably 10°C or higher, and more preferably 20 to 100°C. By having this temperature difference of 10°C or higher, even better seal strength can be achieved.

[0033] The third layer (18c) may include a thermosetting resin instead of PET or PET-based resin in terms of heat resistance and seal strength, or it may include both PET or PET-based resin and a thermosetting resin. Examples of thermosetting resins include polyimide resin, phenolic resin, urea resin, melamine resin, unsaturated polyester resin, urethane resin, allyl resin, epoxy resin, furan resin, and silicone resin. Among these, one type may be used alone, or two or more types may be used in combination.

[0034] The thickness of the third layer (18c) is preferably 5 to 500 μm, and more preferably 20 to 200 μm. It is easy to secure high seal strength by having a thickness of 5 μm or more of the third layer (18c), while it is possible to achieve low cost by having a thickness of 500 μm or less. In addition, the second layer (18b) and the third layer (18c) described above may have the same composition or different compositions. The inner layer (18) may include, for example, various additives (e.g., flame retardant, slip agent, anti-blocking agent, antioxidant, light stabilizer, tackifier, etc.).

[0035] As described above, the substrate layer (11) has a melting peak temperature higher than the melting peak temperature of the inner layer (18). If the inner layer (18) has a multilayer structure, the melting peak temperature of the inner layer (18) refers to the melting peak temperature of the layer with the highest melting peak temperature (e.g., the first layer (18a)). The melting peak temperature of the substrate layer (11) is preferably 290°C or higher, and more preferably 290°C to 350°C. Examples of resin films that can be used as the substrate layer (11) and have a melting peak temperature in the above range include nylon film, PET film, polyamide film, polyphenylene sulfide film (PPS film), etc. As the substrate layer (11), a commercially available film may be used, or the substrate layer (11) may be formed by coating (application and drying of a coating solution). In addition, the substrate layer (11) may be a single-layer structure or a multi-layer structure, and may be formed by coating a thermosetting resin. Also, the substrate layer (11) may include, for example, various additives (e.g., flame retardant, slip agent, anti-blocking agent, antioxidant, light stabilizer, tackifier, etc.).

[0036] Melting peak temperature T of the substrate layer (11) 11 Melting peak temperature T of the inner layer (18) 18 The difference of (T11 - T 18 The temperature is preferably 20°C or higher, and more preferably 40°C to 100°C. By having this temperature difference of 20°C or higher, the deterioration of the appearance of the exterior material (20) caused by the heat seal can be further sufficiently suppressed. The thickness of the substrate layer (11) is preferably 5 to 50 μm, and more preferably 12 to 30 μm.

[0037] Next, the first adhesive layer (12a), the first anti-corrosion treatment layer (13a), the barrier layer (metal foil layer) (15), the second anti-corrosion treatment layer (13b), and the second adhesive layer (12b) will be described. These layers have heat resistance equivalent to or greater than that of the inner layer (18) and the substrate layer (11) described above.

[0038] The adhesive layers (12a, 12b) only need to have sufficient heat resistance, and for example, known adhesives such as general dry lamination adhesives, acid-modified heat-fusible resins, or thermosetting adhesives can be appropriately selected and used. Examples of thermosetting adhesives include polyester-urethane adhesives and epoxy-based adhesives. In terms of heat resistance, it is preferable that the adhesive layers (12a, 12b) are all made of cured products of thermosetting adhesives.

[0039] The barrier layer (15) is a conductive metal layer. As for the material of the barrier layer (15), examples include aluminum or stainless steel, but aluminum is preferred in terms of cost and weight (density). The corrosion-resistant treatment layer (13a, 13b) is intended to protect the barrier layer (15). Examples of the corrosion-resistant treatment layer (13a, 13b) include a layer containing a rare earth element oxide (e.g., cerium oxide) and phosphoric acid or a phosphate. Additionally, as shown in FIG. 2, it is preferable for performance that the corrosion-resistant treatment layer (13a, 13b) be formed on both sides of the barrier layer (15), but considering the cost, only the corrosion-resistant treatment layer (13b) may be placed.

[0040] (Metal terminal)

[0041] FIG. 4 is a cross-sectional view along line IV-IV of the resin film for terminals and metal terminals shown in FIG. 1. Among a pair (two in FIG. 1) of metal terminals (30, 30), one metal terminal (30) is electrically connected to the positive electrode of the capacitor body (10), and the other metal terminal (30) is electrically connected to the negative electrode of the capacitor body (10). The pair of metal terminals (30, 30) extend from the capacitor body (10) to the outside of the outer casing (20). The shape of the pair of metal terminals (30, 30) can be, for example, a flat plate shape.

[0042] Metal can be used as the material for the metal terminal (30). The metal used as the material for the metal terminal (30) can be determined by considering the structure of the capacitor body (10) or the material of each component of the capacitor body (10). For example, if the capacitor (100) is a solid-state battery, it is preferable to use aluminum as the material for the metal terminal (30) connected to the positive electrode of the capacitor body (10). It is preferable to use copper or nickel with a nickel plating layer formed on the surface as the material for the metal terminal (30) connected to the negative electrode of the capacitor body (10).

[0043] The thickness of the metal terminal (30) depends on the size or capacity of the all-solid-state battery. If the all-solid-state battery is small, the thickness of the metal terminal (30) can be, for example, 50 μm or more. Also, if it is a large all-solid-state battery for storage or automotive applications, the thickness of the metal terminal (30) can be appropriately set within the range of, for example, 100 to 500 μm.

[0044] (Resin film for terminals)

[0045] As shown in FIG. 4, the terminal resin film (40) is positioned to cover the outer surface of a portion of the metal terminal (30). By positioning the terminal resin film (40) between the metal terminal (30) and the outer layer (20), the sealing and insulation properties of the capacitor device (100) can be achieved to a higher degree. The terminal resin film (40) has heat resistance equal to or greater than that of the inner layer (18) and the substrate layer (11) described above. Additionally, if the sealing and insulation properties of the capacitor device (100) can be sufficiently secured by the inner layer (18) of the outer layer (20), the terminal resin film (40) does not need to be used.

[0046] A resin film (40) for a terminal is made of a resin composition having adhesion to a metal terminal (30), and the resin composition comprises at least one of a thermosetting resin and a thermoplastic resin having a melting peak temperature of 160°C or higher, and preferably does not include a thermoplastic resin having a melting peak temperature of less than 160°C. According to the resin film (40) for a terminal having such a composition, even if the capacitor is used under temperature conditions of, for example, 100 to 150°C, and even if the temperature of the metal terminal (30) reaches, for example, 100 to 150°C, the sealing performance of the capacitor (100) can be sufficiently maintained. The resin composition comprises at least one of a thermosetting resin and a thermoplastic resin having a melting peak temperature (melting point) of 200°C or higher, and may not include a thermoplastic resin having a melting peak temperature of less than 200°C.

[0047] As a thermosetting resin used in the resin film (40) for the terminal, at least one resin selected from the group consisting of polyimide resin, phenolic resin, urea resin, melamine resin, unsaturated polyester resin, urethane resin, allyl resin, epoxy resin, furan resin, and silicone resin may be used. These thermosetting resins have excellent adhesion to metal materials (e.g., aluminum and nickel) constituting the surface of the metal terminal (30), and also have excellent heat resistance.

[0048] As a thermoplastic resin to be used in the resin film (40) for the terminal, at least one resin selected from the group consisting of PET, the above-mentioned PET-based resin, nylon, polyvinyl alcohol resin, polyvinylidene chloride, polyamide resin, polybutylene terephthalate resin, polyphenylene sulfide, polyetherimide, polysulfone, fluoropolymer, polyamideimide, and acetylcellulose may be used. These thermoplastic resins have excellent adhesion to the metal material (e.g., aluminum and nickel) constituting the surface of the metal terminal (30), and also have excellent heat resistance.

[0049] The resin film (40) for the terminal may have a single-layer structure or a multi-layer structure. When the resin film (40) for the terminal has a single-layer structure (see FIG. 5(a)), the resin composition constituting the resin film (40) for the terminal is preferably one type of thermoplastic resin selected from the group consisting of PET, polyphenylene sulfide, urethane resin, and epoxy resin, and / or one type of thermosetting resin selected from the group consisting of urethane resin and epoxy resin. By using a film made of these resins as the resin film (40) for the terminal, the effect of easily achieving both adhesion to the metal terminal (30) (the resin composition flows appropriately when heat-sealed) and insulation of the metal terminal (30) (the resin composition does not flow excessively when heat-sealed) is exhibited.

[0050] When the terminal resin film (40) has a multilayer structure, the terminal resin film (40) may be configured to have a first layer (40a) made of PET and / or PET-based resin having a melting peak temperature of 160 to 270°C or polyphenylene sulfide (PPS) having a melting peak temperature of 260 to 300°C, and a second layer (40b) made of a thermosetting resin or a thermoplastic resin having a melting peak temperature of 160 to 270°C formed on the surface of the first layer (40a) facing the metal terminal (30) (see FIG. 5(b)). By employing PET and / or PET-based resin or PPS, which have a sufficiently high melting peak temperature, as the resin constituting the first layer (40a), the first layer (40a) does not melt during heat sealing, thereby enabling excellent insulation of the metal terminal (30). The melting peak temperature of the resin (PET and / or PET-based resin) constituting the first layer (40a) may be 210°C or higher. The melting peak temperature of the resin (PET and / or PET-based resin) constituting the second layer (40b) may be 200°C or higher. The melting peak temperature S of the first layer (40a) A and the melting peak temperature S of the second layer (40b) B The difference of (S A - S B The temperature difference is preferably 10°C or higher, and more preferably 20°C to 100°C. By having a temperature difference of 10°C or higher, excellent insulation of the metal terminal (30) can be achieved.

[0051] The thickness of the first layer (40a) is preferably 5 to 500 μm, and more preferably 20 to 200 μm. Since the thickness of the first layer (40a) is 5 μm or more, it is easy to secure insulation, while the thickness is 500 μm or less, it is possible to achieve cost reduction. The thickness of the second layer (40b) is preferably 5 to 500 μm, and more preferably 20 to 200 μm. Since the thickness of the second layer (40b) is 5 μm or more, it is easy to secure sealing, while the thickness is 500 μm or less, it is possible to achieve cost reduction.

[0052] When the resin film (40) for the terminal has a multilayer structure having first and second layers (40a, 40b), a third layer (40c) may be additionally provided on the surface opposite to the side where the second layer (40b) is formed in the first layer (40a) (see FIG. 5(c)). The third layer (40c) may be composed of a thermosetting resin or a thermoplastic resin having a melting peak temperature of 160 to 270°C.

[0053] When the first layer (40a) is made of a thermosetting resin, it is preferable to use a thermosetting resin with higher fluidity than the thermosetting resin constituting the first layer (40a) as the second layer (40b). With this configuration, excellent adhesion to the metal terminal (30) can be achieved by the second layer (40b) during heat sealing. Additionally, as the third layer (40c), a thermosetting resin with higher fluidity than the thermosetting resin constituting the first layer (40a) may be used. With this configuration, a capacitor device (100) with even better sealing properties can be obtained.

[0054] The thickness of the third layer (40c) is preferably 5 to 500 μm, and more preferably 20 to 200 μm. It is easy to ensure sealing properties when the thickness of the third layer (40c) is 5 μm or more, while it is possible to achieve cost reduction when it is 500 μm or less.

[0055] Although the embodiments of the present disclosure have been described in detail above, the present invention is not limited to the above embodiments. For example, in the above embodiments, an all-solid-state battery was exemplified as a storage device to which the outer material (20) is applied, but the outer material (20) may be applied to other storage devices (e.g., lithium-ion batteries).

[0056] Examples

[0057] The present disclosure is described more specifically below based on examples, but the present invention is not limited to the following examples.

[0058] <Manufacture of Exterior Materials>

[0059] (Example 1)

[0060] As a substrate layer, a high-heat-resistant polyamide film (thickness: 25 μm) with a melting peak temperature of 300 °C was prepared. As a metal foil layer, an aluminum foil (thickness: 40 μm) was prepared. As an inner layer, a PET film (thickness: 75 μm, single-layer structure) with a melting peak temperature of 255 °C was prepared. An exterior material related to this embodiment was obtained by laminating the substrate layer and the metal foil layer with a thermosetting adhesive (polyester-urethane type), and by laminating the metal foil layer and the inner layer with the same adhesive.

[0061] (Example 2)

[0062] An exterior material related to this example was obtained in the same manner as in Example 1, except that a PPS film (thickness: 100 μm) with a melting peak temperature of 290 °C was used instead of a high heat-resistant polyamide film as the substrate layer.

[0063] (Example 3)

[0064] An exterior material related to this example was obtained in the same manner as in Example 1, except that an epoxy-based thermosetting adhesive was used instead of a polyester-urethane-based thermosetting adhesive.

[0065] (Example 4)

[0066] An exterior material related to this example was obtained in the same manner as in Example 1, except that a polypropylene-based adhesive (melting peak temperature: 85°C) was used instead of a polyester-urethane-based thermosetting adhesive.

[0067] (Comparative Example 1)

[0068] As a substrate layer, a nylon film (thickness: 25 μm) with a melting peak temperature of 225 °C was prepared. As a metal foil layer, an aluminum foil (thickness: 40 μm) was prepared. As an inner layer, a polypropylene-based film (thickness: 75 μm, single-layer structure) with a melting peak temperature of 140 °C was prepared. An exterior material related to the present comparative example was obtained by laminating the substrate layer and the metal foil layer with a polypropylene-based adhesive (melting peak temperature: 85 °C), and simultaneously laminating the metal foil layer and the inner layer with the same adhesive.

[0069] (Comparative Example 2)

[0070] An exterior material related to this comparative example was obtained in the same manner as in Example 1, except that a PET film (thickness: 25 μm) with a melting peak temperature of 255 °C was used instead of a high heat-resistant polyamide film as the substrate layer.

[0071] <Evaluation of Time Strength>

[0072] Two exterior materials manufactured in each example were cut to a size of 60 mm × 80 mm, and the short sides were butted together and heat-sealed under conditions of 280 ℃, a surface pressure of 0.5 MPa, and a time of 10 seconds. A sample for measurement was obtained by cutting the heat-sealed portion to a width of 15 mm. For each sample, the seal strength under high temperature conditions was measured under the following conditions.

[0073] Measuring device: Universal material testing machine manufactured by INSTRON

[0074] Measured temperature: 150 ℃

[0075] Measurement timing: Measurement was started 5 seconds after the sample was introduced under temperature conditions of 150°C.

[0076] Measurement Method: The peel strength (heat seal strength) was measured in accordance with the method described in JIS K6854-2: 1990 “Adhesives - Peel Adhesion Strength Test - Part 2: 180-Degree Peel” (Peel method: T-shaped, peel speed 50 mm / min). The evaluation was conducted according to the following criteria. The results are shown in Tables 1 and 2.

[0077] "A": Peel strength of 10 N / 15 mm or more

[0078] "B": Peel strength less than 10 N / 15 mm

[0079] <Evaluation of Appearance>

[0080] An appearance evaluation was conducted by visually inspecting the heat seal portion of the sample after the seal strength evaluation. The evaluation was performed according to the following criteria, and Evaluation C was deemed unsuitable. The results are shown in Table 1.

[0081] "A": Immediately after the time, no melting is observed on the surface of the substrate, nor is discoloration observed.

[0082] "B": Although melting is not confirmed on the surface of the substrate layer immediately after the time, discoloration is confirmed.

[0083] "C": Melting is confirmed on the surface of the substrate layer immediately after the time.

[0084]

[0085]

[0086] Industrial applicability

[0087] According to the present disclosure, an outer material that is useful for manufacturing a capacitor with an excellent appearance and also has excellent heat resistance, and a capacitor using the same are provided. Explanation of the symbols

[0088] 10: Storage device body 11 : Base layer 12a: First adhesive layer 15 : Barrier layer (metal foil layer) 12b: Second adhesive layer 18 : Inner layer 18a: 1st layer 18b: Second layer 18th century: Third layer 20 : Exterior materials 30 : Metal terminal (current extraction terminal) 40: Resin film for terminals 100 : Energy storage device

Claims

Claim 1 delete Claim 2 An exterior material for a storage device, having a laminated structure comprising, in this order, a substrate layer, a first adhesive layer, a metal foil layer, a second adhesive layer, and an inner layer comprising a polyester resin, wherein the inner layer has a multilayer structure, a first layer comprising a polyester resin and having a melting peak temperature of 170 to 280°C, and a second layer formed on the inner surface of the first layer and comprising a polyester resin, wherein the second layer has a melting peak temperature in the range of 160 to 270°C and has a melting peak temperature lower than the melting peak temperature of the first layer, and the substrate layer has a melting peak temperature higher than the melting peak temperature of the inner layer. Claim 3 In Clause 2, an exterior material for an all-solid-state battery. Claim 4 In claim 2, the melting point T of the first layer A and the melting point T of the second layer above B The difference of (T A - T B Exterior material with a temperature of 10 ℃ or higher. Claim 5 An exterior material according to claim 2, further comprising a third layer formed on a surface opposite to the side on which the second layer is formed in the first layer, wherein the third layer comprises a polyester resin and has a melting peak temperature in the range of 160 to 270°C and is lower than the melting peak temperature of the first layer. Claim 6 In claim 2, the exterior material further comprises a third layer formed on a surface opposite to the side on which the second layer is formed in the first layer, wherein the third layer comprises a thermosetting resin. Claim 7 In claim 2, the exterior material wherein the polyester resin is at least one of polyethylene terephthalate and polyethylene terephthalate-based resin. Claim 8 An exterior material according to claim 7, wherein the polyethylene terephthalate-based resin comprises a structural unit derived from ethylene glycol, a structural unit derived from terephthalic acid, and other structural units, and the dihydric alcohol component from which the other structural units are derived is at least one selected from the group consisting of neopentyl glycol, 1,4-butadiol, and diethylene glycol. Claim 9 In claim 7, the polyethylene terephthalate-based resin comprises a structural unit derived from ethylene glycol, a structural unit derived from terephthalic acid, and other structural units, wherein the acid component from which the other structural units are derived is at least one selected from the group consisting of isophthalic acid, adipic acid, and sebacic acid, an exterior material. Claim 10 An exterior material according to claim 2, wherein the first adhesive layer and the second adhesive layer are composed of a cured product of a thermosetting adhesive. Claim 11 A capacitor having a capacitor body, a current extraction terminal extending from the capacitor body, and an exterior material described in any one of claims 2 to 10 that clamps the current extraction terminal and accommodates the capacitor body. Claim 12 In claim 11, a storage device that is an all-solid-state battery. Claim 13 delete Claim 14 delete

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