Exterior material for power storage device and manufacturing method therefor, and method for selecting sealant film used as sealant layer in exterior material for power storage device

Abstract

To provide an exterior material for a power storage device, which is capable of achieving both seal strength under high temperatures and initial seal strength at a sufficiently high level.SOLUTION: An exterior material for a power storage device according to an aspect of the present disclosure has a laminated structure including at least a base material layer, a barrier layer and a sealant layer in the order. The sealant layer has at least one secondary dispersion peak γ in the range of -130°C to -50°C in a profile of a loss tangent tan δ obtained by a dynamic viscoelasticity measurement at a condition of 1.0 Hz.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to an exterior material for a power storage device, a method for manufacturing the same, and a method for selecting a sealant film used as a sealant layer in the exterior material for a power storage device.

Background Art

[0002] As power storage devices, for example, secondary batteries such as lithium ion batteries, nickel metal hydride batteries, and lead storage batteries, and electrochemical capacitors such as electric double layer capacitors are known. Further miniaturization of power storage devices is required due to miniaturization of portable devices or limitation of installation space, and lithium ion batteries with high energy density have attracted attention. Conventionally, a metal can has been used as an exterior material for lithium ion batteries, but a multilayer film that is lightweight, has high heat dissipation, and can be manufactured at low cost is now being used.

[0003] A lithium ion battery using the above multilayer film as an exterior material is called a laminated lithium ion battery. The exterior material covers the battery contents (positive electrode, separator, negative electrode, electrolyte, etc.) and prevents 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 exterior material by cold forming, accommodating the battery contents in the concave portion, and folding back the remaining part of the exterior material and sealing the edge portion by heat sealing (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Incidentally, as a next-generation battery for lithium-ion batteries, research and development of a power storage device called an all-solid-state battery has been carried out. The all-solid-state battery is characterized by using a solid electrolyte without using an organic electrolyte as an electrolyte substance. While a lithium-ion battery cannot be used under temperature conditions higher than the boiling point temperature of the electrolyte (about 80°C), the all-solid-state battery can be used under temperature conditions exceeding 100°C, and the conductivity of lithium ions can be increased by operating it under high temperature conditions (for example, 100 to 150°C).

[0006] However, when manufacturing a laminate-type all-solid-state battery using the above-described laminate as an exterior material, the hermeticity of the package of the all-solid-state battery may become insufficient due to the insufficient heat resistance of the exterior material.

[0007] The present disclosure provides an exterior material for a power storage device and a method for manufacturing the same, which can achieve both a seal strength at high temperature and an initial seal strength at a sufficiently high level. The present disclosure also provides a method for selecting a sealant film used as a sealant layer in an exterior material for a power storage device.

Means for Solving the Problems

[0008] The exterior material for a power storage device according to one aspect of the present disclosure has a laminated structure including at least a base material layer, a barrier layer, and a sealant layer in this order, and the sealant layer has at least one sub-dispersion peak γ in the range of -130°C to -50°C of the profile of the loss tangent tanδ obtained by dynamic viscoelasticity measurement under the condition of 1.0 Hz.

[0009] The secondary dispersion peak γ is an indicator of the molecular motion of the resin material constituting the sealant layer. Specifically, it is a parameter that reflects the local torsional motion of the main chain and the thermal motion of the entire side chain in the crystalline and amorphous parts of the resin material. According to the study by the present inventors, the sealant layer that satisfies the above requirements regarding the secondary dispersion peak γ contains a resin material that starts molecular motion at a relatively high temperature and can exhibit excellent sealing strength at high temperatures. Note that it means that the sealant layer has greater flexibility as the temperature at which the secondary dispersion peak γ appears is lower, and has greater heat resistance as the temperature is higher.

[0010] Preferably, the sealant layer has at least one main dispersion peak α in the range of 30°C to 130°C of the above tanδ profile. The main dispersion peak α is a parameter that reflects the microscopic Brownian motion of the molecular chains in the amorphous part near the glass transition temperature (Tg) of the resin material contained in the sealant layer. According to the study by the present inventors, the sealant layer that satisfies the above requirements regarding the main dispersion peak α contains a resin material that starts molecular motion at a relatively low temperature (for example, room temperature) and is excellent in flexibility. Therefore, it is possible for the sealant layer to exhibit even more excellent sealing strength (initial sealing strength) under a room temperature environment. Note that it means that the sealant layer has greater flexibility as the temperature at which the main dispersion peak α appears is lower, and has greater heat resistance as the temperature is higher.

[0011] Preferably, the sealant layer contains a plasticizer. By adjusting the content of the plasticizer in the sealant layer, the temperatures at which the secondary dispersion peak γ and the main dispersion peak α appear can be controlled. For example, by increasing the content of the plasticizer, the secondary dispersion peak γ and the main dispersion peak α can be shifted to the lower temperature side.

[0012] The sealant layer preferably contains a hydrogen sulfide adsorbing substance. In an all-solid-state battery, as the electrolyte, for example, a sulfide-based electrolyte, an oxide-based electrolyte, or an organic polymer-based electrolyte is used. Among these, when a sulfide-based electrolyte is used, if moisture enters the cell, hydrogen sulfide is generated, and there is concern about a decrease in the adhesion between the barrier layer (for example, a metal foil) and the sealant layer. By the sealant layer containing a hydrogen sulfide adsorbing substance, excellent seal strength at room temperature and high temperature can be maintained even after hydrogen sulfide exposure. The exterior material for the power storage device may further include an adhesive layer provided between the barrier layer and the sealant layer. In this case, the adhesive layer may contain a hydrogen sulfide adsorbing substance. From the viewpoint of the content of the hydrogen sulfide adsorbing substance, it is preferable that at least the sealant layer contains a hydrogen sulfide adsorbing substance.

[0013] The exterior material for the power storage device preferably further includes a corrosion prevention treatment layer provided on at least one surface of the barrier layer. By the exterior material for the power storage device having a corrosion prevention treatment layer with acid resistance, excellent seal strength at room temperature and high temperature can be maintained even after hydrogen sulfide exposure, and an improvement in seal strength can also be confirmed before hydrogen sulfide exposure.

[0014] One aspect of the present disclosure relates to a method for selecting a sealant film used as a sealant layer in an exterior material for a power storage device. This selection method includes the following steps. (A) A step of performing dynamic viscoelasticity measurement on the sealant film to be evaluated under the condition of 1.0 Hz (B) A step of determining whether or not there is at least one sub-dispersion peak γ in the range of -130°C to -50°C of the tanδ profile obtained by the above dynamic viscoelasticity measurement

[0015] By using a sealant film having at least one sub-dispersion peak γ in the range of -130°C to -50°C of the tanδ profile as the sealant layer, an exterior material for a power storage device can be manufactured in which both the seal strength at high temperature and the initial seal strength are at a sufficiently high level.

[0016] The manufacturing method of the exterior material for a power storage device according to one aspect of the present disclosure includes, in the above selection method, a step of preparing a sealant film determined to have at least one sub-dispersion peak γ in the range of -130°C to -50°C of the profile of the above tanδ, and a step of laminating the sealant film and the barrier layer.

Advantages of the Invention

[0017] According to the present disclosure, there are provided an exterior material for a power storage device and a manufacturing method thereof that can achieve both a sufficiently high level of seal strength and initial seal strength at high temperatures. Further, according to the present disclosure, there is provided a method for selecting a sealant film used as a sealant layer in an exterior material for a power storage device.

Brief Description of the Drawings

[0018]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0019] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant descriptions are omitted. Also, the dimensional ratios in the drawings are not limited to the illustrated ratios.

[0020] <Power storage device> FIG. 1 is a perspective view showing a schematic configuration of a power storage device according to the present embodiment. In FIG. 1, as an example of the power storage device 100, a all-solid-state battery is illustrated as an example, and the following description will be given. Note that the power storage device having the configuration shown in FIG. 1 may be referred to as a battery pack or a battery cell.

[0021] The power storage device 100 is an all-solid-state battery, and includes a power storage device main body 50, an exterior member 10, a pair of metal terminals 30, and a terminal resin film 40 (tab sealant). The power storage device main body 50 is a battery main body that performs charge and discharge. The exterior member 10 covers the surface of the power storage device main body 50 and is disposed so as to be in contact with a part of the terminal resin film 40.

[0022] [Exterior member] FIG. 2 is a cross-sectional view showing an example of a cut surface of the exterior member 10. The exterior member 10 has a multilayer structure including a base material layer 11, a first adhesive layer 12, a barrier layer 13, a corrosion prevention treatment layer 14, a second adhesive layer 17, and a sealant layer 16 in this order from the outside toward the inside (the power storage device main body 50 side).

[0023] (Sealant layer) The sealant layer 16 has at least one sub-dispersion peak γ in the range of -130°C to -50°C of the profile of the loss tangent tanδ obtained by dynamic viscoelasticity measurement under the condition of 1.0 Hz. By the sealant layer 16 satisfying this condition, the exterior member 10 can achieve both the seal strength at high temperature and the initial seal strength (seal strength at room temperature) at a sufficiently high level. The temperature range in which the sub-dispersion peak γ exists is preferably -120°C to -60°C, more preferably -110°C to -70°C, from the viewpoint of the seal strength at room temperature and high temperature. When the temperature at which the sub-dispersion peak γ exists is less than -130°C, the heat resistance of the sealant layer 16 becomes poor and the seal strength at high temperature may become insufficient. On the other hand, when the temperature at which the sub-dispersion peak γ exists exceeds -50°C, the flexibility of the sealant layer 16 becomes poor and the seal strength at room temperature may become insufficient.

[0024] The above tanδ can be calculated as the loss tangent tanδ from the loss elastic modulus E’’ and the storage elastic modulus E’ by, for example, immersing the exterior material in an aqueous sodium hydroxide solution to dissolve the barrier layer (metal foil), taking out the film composed only of the sealant layer, and measuring the film under the following conditions using a dynamic viscoelasticity apparatus (manufactured by SII, trade name: DMS6100) in accordance with the method conforming to JIS K7244-4. · Peeling mode: Tension · Heating rate: 2°C / min · Temperature range: -150 to 150°C · Frequency: 1.0 Hz

[0025] The sealant layer 16 preferably has at least one main dispersion peak α in the range of 30°C to 130°C of the above tanδ profile. By the sealant layer 16 satisfying this condition, the exterior material 10 exhibits more excellent initial seal strength (seal strength at room temperature). The temperature range where the main dispersion peak α exists is preferably 40°C to 110°C, more preferably 50°C to 100°C, from the viewpoint of the seal strength at room temperature. When the temperature where the main dispersion peak α exists is less than 30°C, the heat resistance of the sealant layer 16 tends to be poor and the seal strength at high temperatures tends to be insufficient. On the other hand, when the temperature where the main dispersion peak α exists exceeds 130°C, the flexibility of the sealant layer 16 tends to be poor and the seal strength at room temperature tends to be insufficient.

[0026] The temperatures at which the sub-dispersion peak γ and the main dispersion peak α of the sealant layer 16 appear can be controlled, for example, by the structure of the base resin material contained in the sealant layer 16, the draw ratio of the sealant layer 16, or the blending amount of additives (for example, plasticizers). The sealant layer 16 contains additives as required. Examples of the additives include plasticizers, antioxidants, slip agents, flame retardants, AB agents, light stabilizers, dehydrating agents, and tackifiers.

[0027] Examples of the base resin material contained in the sealant layer 16 include polyester-based, polyolefin-based, or polyamide-based resins.

[0028] The polyester resin can be obtained by copolymerizing an acid component and a glycol component. Examples of the acid component include phthalic acid, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, cyclohexanedicarboxylic acid, adipic acid, and sebacic acid. Examples of the glycol component include ethylene glycol, butanediol, pentanediol, hexanediol, neopentyl glycol, diethylene glycol, polytetramethylene glycol, cyclohexanedimethanol, and propanediol. According to the studies of the present inventors, in general PET (a copolymer of terephthalic acid and ethylene glycol), the temperature range where the sub-dispersion peak γ exists is outside the range of -130°C to -50°C, and the seal strength at room temperature is insufficient. When a plasticizer is not blended in the sealant layer 16, the sealant layer 16 preferably contains a polyester resin in which two or more glycol components are copolymerized with one kind of acid component.

[0029] Examples of the polyolefin resin include polyethylene and polypropylene resins. In general polyolefin resins, since the heat resistance is poor, it is preferable to use those in which polyethylene, polypropylene, etc. are modified with an amide or the like. Further, when the sealant layer 16 and the barrier layer 13 are bonded together by thermal lamination, from the viewpoint of metal adhesion, it is preferable to use an acid-modified or amide-modified polyolefin such as carboxylic acid or maleic anhydride.

[0030] Examples of the polyamide resin include nylon 6 and nylon 6,6.

[0031] From the viewpoint of adjusting the temperature at which the secondary dispersion peak γ and the primary dispersion peak α of the sealant layer 16 appear, the sealant layer 16 preferably contains a plasticizer. As the plasticizer, for example, an ester-based compound can be used. Specific examples include glycol diesters, adipic acid esters, phthalic acid esters, diacetyl monoacyl glycerol derivatives, and esters having an ether skeleton. Depending on the base resin material of the sealant layer 16, the content of the plasticizer in the sealant layer 16 is preferably 30% by mass or less based on the mass of the sealant layer 16. When an excessive amount of plasticizer is blended into the sealant layer 16, the temperature at which the secondary dispersion peak γ and the primary dispersion peak α appear decreases excessively, and the cohesive force tends to decrease.

[0032] The sealant layer 16 may have a single-layer structure or a multilayer structure of two or more layers (see FIGS. 3(a) to 3(c)). When the sealant layer has a single-layer structure, its thickness is preferably 10 to 300 μm, more preferably 20 to 100 μm. When the thickness of the sealant layer 16 is 10 μm or more, it is easy to ensure sealing performance and insulation performance. On the other hand, when it is 300 μm or less, it is possible to secure the cell volume.

[0033] FIG. 3(b) is a cross-sectional view schematically showing the sealant layer 16 having a two-layer structure. The sealant layer 16 shown in the figure has a first resin layer 16a and a second resin layer 16b formed on the inner surface of the first resin layer 16a. The first resin layer 16a may be made of, for example, a material different from that of the second resin layer 16b, or may have a different thickness from that of the second resin layer 16b. The thicknesses of the first resin layer 16a and the second resin layer 16b are each, for example, 5 to 300 μm, and may be 20 to 200 μm. As shown in FIG. 3(c), the sealant layer 16 may have a three-layer structure and may further include a third resin layer 16c.

[0034] When the electrolyte of the all-solid-state battery is a sulfide-based electrolyte, the sealant layer 16 preferably contains a hydrogen sulfide adsorbing substance. By containing a hydrogen sulfide adsorbing substance in the sealant layer 16, excellent seal strength at room temperature and high temperature can be maintained even after hydrogen sulfide exposure. As the hydrogen sulfide adsorbing substance, a material having the performance of absorbing or adsorbing hydrogen sulfide can be used. Specific examples thereof include zinc oxide, amorphous metal silicate, hydroxide of zirconium-lanthanoid element, tetravalent metal phosphate, potassium permanganate, sodium permanganate, aluminum oxide, iron hydroxide, silver sulfate, silver acetate, isocyanate compound, aluminum silicate, potassium aluminum sulfate, zeolite, activated carbon, amine-based compound, and ionomer.

[0035] The content of the hydrogen sulfide adsorbing substance in the sealant layer 16 is preferably 1 to 50% by mass, more preferably 2 to 25% by mass, and still more preferably 5 to 15% by mass based on the mass of the sealant layer 16. When the content of the hydrogen sulfide adsorbing substance in the sealant layer 16 is 1% by mass or more, the adsorption effect of hydrogen sulfide is exhibited. On the other hand, when it is 50% by mass or less, the adhesion and sealability of the sealant layer 16 can be compatible. When the sealant layer 16 has a multilayer structure, all or some of the layers may contain a hydrogen sulfide adsorbing substance. In addition, a layer other than the sealant layer 16 (for example, the second adhesive layer 17) in the exterior material 10 may contain a sulfide-based electrolyte, but from the viewpoint of the content of the hydrogen sulfide adsorbing substance, it is preferable that at least the sealant layer 16 contains a hydrogen sulfide adsorbing substance.

[0036] (Base material layer) The base material layer 11 imparts heat resistance in the sealing process when manufacturing the power storage device and plays a role in suppressing the generation of pinholes that may occur during molding and distribution. Especially in the case of the exterior material of a large-scale power storage device, scratch resistance, chemical resistance, insulation, etc. can also be imparted.

[0037] The base material layer 11 is preferably a layer formed of an insulating resin. As the resin, polyester resin, polyamide resin, polyimide resin, polyamideimide resin, polyether ketone resin, polyphenylene sulfide resin, polyetherimide resin, polysulfone resin, fluororesin, phenol resin, melamine resin, urethane resin, allyl resin, silicone resin, epoxy resin, furan resin, acetyl cellulose resin, etc. can be used.

[0038] When these resins are applied to the base material layer, they may be in the form of a stretched or unstretched film, or in the form of a coating film. Also, the base material layer may be single-layer or multi-layer. In the case of multi-layers, different resins can be combined and used. If it is a film, a co-extruded one or a laminated one via an adhesive can be used. In the case of a coating film, one coated the number of times of lamination can be used, and a multi-layer can also be formed by combining a film and a coating film.

[0039] Among these resins, as the base material layer, polyester resin and polyamide resin are preferable because of their excellent moldability. Examples of the polyester resin include polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate. Examples of the polyamide resin constituting the polyamide film include nylon 6, nylon 6,6, a copolymer of nylon 6 and nylon 6,6, nylon 6, nylon 9T, nylon 10, polymetaxylylene adipamide (MXD6), nylon 11, nylon 12, etc.

[0040] When these resins are used in the form of a film, it is preferably a biaxially stretched film. Examples of the stretching method in the biaxially stretched film include, for example, the sequential biaxial stretching method, the tubular biaxial stretching method, the simultaneous biaxial stretching method, etc. From the viewpoint of obtaining better deep drawing moldability, the biaxially stretched film is preferably stretched by the tubular biaxial stretching method.

[0041] The thickness of the base material layer 11 is preferably 6 to 40 μm, more preferably 10 to 30 μm. When the thickness of the base material layer 11 is 6 μm or more, the pinhole resistance and insulation of the exterior material 10 tend to be improved. When the thickness of the base material layer 11 exceeds 40 μm, the total thickness of the exterior material 10 tends to increase.

[0042] The melting point peak temperature of the base material layer is higher than the melting point peak temperature of the sealant layer in order to suppress the deformation of the base material during sealing, and is preferably 30 °C or more.

[0043] (First adhesive layer) The first adhesive layer 12 is a layer that adheres the base material layer 11 and the barrier layer 13. Specific examples of the material constituting the first adhesive layer 12 include polyurethane resins obtained by reacting a main agent such as polyester polyol, polyether polyol, acrylic polyol, and carbonate polyol with a bifunctional or higher isocyanate compound. The above-mentioned various polyols can be used alone or in combination of two or more according to the functions and performances required for the exterior material. Further, according to the performance required for the adhesive, various other additives and stabilizers may be blended into the above-mentioned polyurethane resin.

[0044] The thickness of the first adhesive layer 12 is not particularly limited, but from the viewpoints of obtaining desired adhesive strength, followability, processability, etc., for example, 1 to 10 μm is preferable, and 3 to 7 μm is more preferable.

[0045] (Barrier layer) The barrier layer 13 has a water vapor barrier property that prevents moisture from entering the interior of the power storage device. Further, the barrier layer 13 has ductility for deep drawing molding. As the barrier layer 13, various metal foils such as aluminum, stainless steel, and copper, and metal vapor deposition films, inorganic oxide vapor deposition films, carbon-containing inorganic oxide vapor deposition films, and films provided with these vapor deposition films can be used. From the viewpoints of mass (specific gravity), moisture-proof property, processability, and cost, metal foil is preferable, and aluminum foil is more preferable.

[0046] As the aluminum foil, particularly annealed soft aluminum foil can be preferably used from the viewpoint of imparting desired ductility during molding. However, for the purpose of further improving pinhole resistance and imparting ductility during molding, it is more preferable to use an aluminum foil containing iron. The iron content in the aluminum foil is preferably 0.1 to 9.0% by mass, more preferably 0.5 to 2.0% by mass, based on 100% by mass of the aluminum foil. When the iron content is 0.1% by mass or more, the exterior material 10 having more excellent pinhole resistance and ductility can be obtained. When the iron content is 9.0% by mass or less, the exterior material 10 having more excellent flexibility can be obtained. Although untreated aluminum foil may be used, it is preferable to use degreased aluminum foil in terms of imparting corrosion resistance. When degreasing the aluminum foil, the degreasing treatment may be performed on only one side of the aluminum foil or on both sides.

[0047] The thickness of the barrier layer 13 is not particularly limited, but preferably 9 to 200 μm, more preferably 15 to 100 μm, in consideration of barrier properties, pinhole resistance, and processability.

[0048] (Corrosion prevention treatment layer) The corrosion prevention treatment layer 14 is a layer provided on the surface of the metal thin layer or the like constituting the barrier layer 13 to prevent corrosion. As the corrosion prevention treatment layer 14, for example, it is formed by degreasing treatment, hot water conversion treatment, anodizing treatment, chemical conversion treatment, or a combination of these treatments.

[0049] Examples of the degreasing treatment include acid degreasing or alkaline degreasing. Examples of the acid degreasing include methods using an inorganic acid alone such as sulfuric acid, nitric acid, hydrochloric acid, or hydrofluoric acid, or a mixed solution thereof. Further, as the acid degreasing, by using an acid degreasing agent in which a fluorine-containing compound such as ammonium bifluoride monosodium is dissolved in the above inorganic acid, not only the degreasing effect of aluminum can be obtained, but also a fluoride of aluminum which is passive can be formed, which is effective in terms of acid resistance to hydrofluoric acid. Examples of the alkaline degreasing include methods using sodium hydroxide or the like.

[0050] Examples of the hydrothermal conversion treatment include, for example, boehmite treatment in which an aluminum foil is immersed in boiling water added with triethanolamine. Examples of the anodizing treatment include, for example, alumite treatment.

[0051] Examples of the chemical conversion treatment include immersion type and coating type. Examples of the immersion type chemical conversion treatment include, for example, chromate treatment, zirconium treatment, titanium treatment, vanadium treatment, molybdenum treatment, calcium phosphate treatment, strontium hydroxide treatment, cerium treatment, ruthenium treatment, or various chemical conversion treatments composed of a mixed phase thereof. On the other hand, examples of the coating type chemical conversion treatment include a method of applying a coating agent having corrosion prevention performance onto the barrier layer 13.

[0052] Among these corrosion prevention treatments, when at least a part of the corrosion prevention treatment layer is formed by any one of the hydrothermal conversion treatment, anodizing treatment, and chemical conversion treatment, it is preferable to perform the above-described degreasing treatment in advance. In addition, when a degreased metal foil such as a metal foil passed through an annealing process is used as the barrier layer 13, there is no need to perform degreasing treatment again in the formation of the corrosion prevention treatment layer 14.

[0053] The coating agent used for the coating type chemical conversion treatment preferably contains trivalent chromium. Further, the coating agent may contain at least one polymer selected from the group consisting of a cationic polymer and an anionic polymer described later.

[0054] Among the above-mentioned treatments, particularly in the hot water conversion treatment and anodizing treatment, the surface of the aluminum foil is dissolved by the treatment agent to form aluminum compounds (boehmite, alumite) excellent in corrosion resistance. Therefore, since a co-continuous structure is formed from the barrier layer 13 to the corrosion prevention treatment layer 14 using the aluminum foil, the above treatment is included in the definition of chemical conversion treatment. On the other hand, as will be described later, it is also possible to form the corrosion prevention treatment layer 14 only by a pure coating method that is not included in the definition of chemical conversion treatment. As this method, for example, a method using a sol of rare earth element oxide such as cerium oxide with an average particle size of 100 nm or less, which has an aluminum corrosion prevention effect (inhibitor effect) and is also a suitable material from an environmental aspect, can be mentioned. By using this method, it is possible to impart a corrosion prevention effect to a metal foil such as an aluminum foil even by a general coating method.

[0055] Examples of the sol of the rare earth element oxide include sols using various solvents such as aqueous, alcohol-based, hydrocarbon-based, ketone-based, ester-based, and ether-based solvents. Among them, an aqueous sol is preferable. In the sol of the rare earth element oxide, inorganic acids such as nitric acid, hydrochloric acid, and phosphoric acid or their salts, and organic acids such as acetic acid, malic acid, ascorbic acid, and lactic acid are usually used as dispersion stabilizers to stabilize the dispersion thereof. Among these dispersion stabilizers, phosphoric acid in particular is expected to (1) stabilize the dispersion of the sol, (2) improve the adhesion to the barrier layer 13 by utilizing the aluminum chelating ability of phosphoric acid, and (3) improve the cohesive force of the corrosion prevention treatment layer 14 (oxide layer) due to the easy occurrence of dehydration condensation of phosphoric acid even at low temperatures in the exterior material 10.

[0056] Since the corrosion prevention treatment layer 14 formed by the sol of the rare earth element oxide is an aggregate of inorganic particles, there is a possibility that the cohesive force of the layer itself may decrease even after passing through the drying and curing process. Therefore, in this case, the corrosion prevention treatment layer is preferably complexed with the following anionic polymer or cationic polymer in order to supplement the cohesive force.

[0057] The corrosion prevention treatment layer is not limited to the layers described above. For example, like the known coating type chromate, it may be formed using a treatment agent in which phosphoric acid and a chromium compound are blended in a resin binder (such as aminophenol). By using this treatment agent, a layer having both a corrosion prevention function and adhesiveness can be obtained. Also, although it is necessary to consider the stability of the coating liquid, a coating agent in which a rare earth element oxide sol and a polycationic polymer or a polyanionic polymer are liquefied in advance can be used to form a layer having both a corrosion prevention function and adhesiveness.

[0058] The mass per unit area of the corrosion prevention treatment layer is preferably 0.005 to 0.200 g / m², and more preferably 0.010 to 0.100 g / m², whether it is a multilayer structure or a single layer structure. If the mass per unit area is 0.005 g / m² or more, it is easy to impart a corrosion prevention function to the barrier layer 13. Also, even if the mass per unit area exceeds 0.200 g / m², the corrosion prevention function does not change much. On the other hand, when using a rare earth element oxide sol, if the coating film is thick, curing by heat during drying may be insufficient, and there is a risk of a decrease in cohesive force. The thickness of the corrosion prevention treatment layer 14 can be converted from its specific gravity. 2 is preferable, and 0.010~0.100g / m 2 is more preferable. If the mass per unit area is 0.005 g / m 2 or more, it is easy to impart a corrosion prevention function to the barrier layer 13. Also, if the mass per unit area exceeds 0.200 g / m 2 the corrosion prevention function does not change much. On the other hand, when using a rare earth element oxide sol, if the coating film is thick, curing by heat during drying may be insufficient, and there is a risk of a decrease in cohesive force. The thickness of the corrosion prevention treatment layer 14 can be converted from its specific gravity.

[0059] From the viewpoint of the adhesiveness between the sealant layer and the barrier layer, the corrosion prevention treatment layer may be, for example, a mode including cerium oxide, 1 to 100 parts by mass of phosphoric acid or phosphate with respect to 100 parts by mass of the cerium oxide, and a cationic polymer, or may be a mode formed by subjecting the barrier layer 13 to a chemical conversion treatment, or may be a mode formed by subjecting the barrier layer to a chemical conversion treatment and containing a cationic polymer.

[0060] (Second Adhesive Layer) The second adhesive layer 17 is a layer that adheres the barrier layer 13 on which the corrosion prevention treatment layer 14 is formed and the sealant layer 16. A general adhesive for adhering the barrier layer 13 and the sealant layer 16 can be used for the second adhesive layer 17.

[0061] When the corrosion prevention treatment layer 14 has a layer containing at least one polymer selected from the group consisting of the cationic polymer and the anionic polymer described above, the second adhesive layer 17 is preferably a layer containing a compound reactive with the polymer contained in the corrosion prevention treatment layer 14 (hereinafter also referred to as "reactive compound").

[0062] For example, when the corrosion prevention treatment layer 14 contains a cationic polymer, the second adhesive layer 17 contains a compound reactive with the cationic polymer. When the corrosion prevention treatment layer 14 contains an anionic polymer, the second adhesive layer 17 contains a compound reactive with the anionic polymer. Further, when the corrosion prevention treatment layer 14 contains a cationic polymer and an anionic polymer, the second adhesive layer 17 contains a compound reactive with the cationic polymer and a compound reactive with the anionic polymer. However, the second adhesive layer 17 does not necessarily have to contain the above two types of compounds, and may contain a compound reactive with both the cationic polymer and the anionic polymer. Here, "reactive" means forming a covalent bond with the cationic polymer or the anionic polymer. Further, the second adhesive layer 17 may further contain an acid-modified polyolefin resin.

[0063] Examples of the compound reactive with the cationic polymer include at least one compound selected from the group consisting of polyfunctional isocyanate compounds, glycidyl compounds, compounds having a carboxy group, and compounds having an oxazoline group.

[0064] Examples of these polyfunctional isocyanate compounds, glycidyl compounds, compounds having a carboxy group, and compounds having an oxazoline group include the polyfunctional isocyanate compounds, glycidyl compounds, compounds having a carboxy group, and compounds having an oxazoline group exemplified above as crosslinking agents for forming a crosslinked structure of the cationic polymer. Among these, polyfunctional isocyanate compounds are preferred in terms of high reactivity with the cationic polymer and easy formation of a crosslinked structure.

[0065] Examples of the compound having reactivity with the anionic polymer include at least one compound selected from the group consisting of glycidyl compounds and compounds having an oxazoline group. Examples of these glycidyl compounds and compounds having an oxazoline group include the glycidyl compounds and compounds having an oxazoline group exemplified above as crosslinking agents for forming a crosslinked structure of the cationic polymer. Among these, glycidyl compounds are preferred in terms of high reactivity with the anionic polymer.

[0066] When the second adhesive layer 17 contains an acid-modified polyolefin resin, the reactive compound preferably also has reactivity with the acidic groups in the acid-modified polyolefin resin (i.e., forms a covalent bond with the acidic groups). Thereby, the adhesiveness with the corrosion prevention treatment layer 14 is further enhanced. In addition, the acid-modified polyolefin resin forms a crosslinked structure, and the solvent resistance of the exterior material 10 is further improved.

[0067] The content of the reactive compound is preferably from an equivalent amount to 10 times the equivalent amount relative to the acidic groups in the acid-modified polyolefin resin. If it is an equivalent amount or more, the reactive compound sufficiently reacts with the acidic groups in the acid-modified polyolefin resin. On the other hand, if it exceeds 10 times the equivalent amount, since the crosslinking reaction with the acid-modified polyolefin resin has reached sufficient saturation, unreacted substances are present, and a decrease in various performances is a concern. Therefore, for example, the content of the reactive compound is preferably 5 to 20 parts by mass (solid content ratio) with respect to 100 parts by mass of the acid-modified polyolefin resin.

[0068] The acid-modified polyolefin resin is obtained by introducing acidic groups into the polyolefin resin. Examples of the acidic groups include carboxy groups, sulfonic acid groups, acid anhydride groups, etc., and maleic anhydride groups and (meth)acrylic acid groups are particularly preferred. As the acid-modified polyolefin resin, for example, the same ones as those used for the modified polyolefin resin in the sealant layer 16 can be used.

[0069] The second adhesive layer 17 may be blended with various additives such as a flame retardant, a slip agent, an anti-blocking agent, an antioxidant, a light stabilizer, and a tackifier.

[0070] Examples of the adhesive for forming the second adhesive layer 17 include a polyurethane resin obtained by reacting a bifunctional or higher isocyanate compound with a main agent such as polyester polyol, polyether polyol, acrylic polyol, or carbonate polyol, and an epoxy resin obtained by reacting an amine compound or the like with a main agent having an epoxy group. These are preferable from the viewpoint of heat resistance.

[0071] The thickness of the second adhesive layer 17 is not particularly limited, but from the viewpoint of obtaining a desired adhesive strength, processability, etc., 1 to 10 μm is preferable, and 2 to 7 μm is more preferable.

[0072] [Metal terminal] FIG. 4 is a cross-sectional view in the IV-IV line direction of the resin film for a terminal and the metal terminal shown in FIG. 1. Among the pair of metal terminals 30, 30, one metal terminal 30 is electrically connected to the positive electrode of the power storage device main body 50, and the other metal terminal 30 is electrically connected to the negative electrode of the power storage device main body 50. The pair of metal terminals 30, 30 extends from the power storage device main body 50 to the outside of the exterior material 10. The shape of the pair of metal terminals 30, 30 can be, for example, a flat plate shape.

[0073] As the material of the metal terminal 30, a metal can be used. The metal serving as the material of the metal terminal 30 may be determined in consideration of the structure of the power storage device main body 50 and the materials of its components. For example, when the power storage device 100 is an all-solid-state battery, it is preferable to use aluminum as the material of the metal terminal 30 connected to the positive electrode of the power storage device main body 50. As the material of the metal terminal 30 connected to the negative electrode of the power storage device main body 50, it is preferable to use copper having a nickel plating layer formed on the surface or nickel.

[0074] The thickness of the metal terminal 30 depends on the size and capacity of the all-solid-state battery. When the all-solid-state battery is small, the thickness of the metal terminal 30 may be, for example, 50 μm or more. In the case of a large all-solid-state battery for power storage or in-vehicle use, etc., the thickness of the metal terminal 30 can be appropriately set within the range of, for example, 100 to 500 μm.

[0075] [Resin film for terminals] As shown in FIG. 4, the resin film 40 for terminals is arranged so as to cover a part of the outer peripheral surface of the metal terminal 30. By arranging the resin film 40 for terminals between the metal terminal 30 and the exterior material 10, the sealing performance and insulation performance of the power storage device 100 can be achieved at an even higher level. The resin film 40 for terminals has heat resistance equivalent to or exceeding that of the above-described sealant layer 16 and base material layer 11. When the sealing performance and insulation performance of the power storage device 100 can be sufficiently ensured by the sealant layer 16 of the exterior material 10, the resin film 40 for terminals may not be used.

[0076] As described above in detail regarding the embodiments of the present disclosure, the present invention is not limited to the above embodiments, and various modifications and changes are possible within the scope of the gist of the present disclosure described within the scope of the claims. For example, in the above embodiments, an embodiment in which the corrosion prevention treatment layer 14 is provided only on one surface (the second adhesive layer 17 side) of the barrier layer 13 is illustrated, but the corrosion prevention treatment layer 14 may also be provided on the other surface (the first adhesive layer 12 side) of the barrier layer 13. Further, for example, when the sealant layer 16 is attached to the barrier layer 13 by thermal lamination, the second adhesive layer 17 may be omitted. When the base material layer 11 is provided by coating or painting, the first adhesive layer 12 may not be provided. In the above embodiments, an all-solid-state battery is illustrated as the power storage device to which the exterior material 10 is applied, but the exterior material 10 may be applied to other power storage devices (for example, lithium-ion batteries).

[0077] Based on the content of the above embodiment, a method for selecting a sealant film may be implemented. That is, this selection method is for selecting a sealant film used as a sealant layer in an exterior material for a power storage device, and includes: (A) a step of performing dynamic viscoelasticity measurement on the sealant film to be evaluated under the condition of 1.0 Hz; and (B) a step of determining whether or not there is at least one sub-dispersion peak γ in the range of -130 °C to -50 °C of the tanδ profile obtained by the above dynamic viscoelasticity measurement. The matters described in the above embodiment may be appropriately applied to this selection method.

Example

[0078] Hereinafter, the present disclosure will be described more specifically based on examples, but the present disclosure is not limited to the following examples.

[0079] [Materials Used] The materials used in the examples and comparative examples are shown below.

[0080] <Base Material Layer (Thickness 25 μm)> A polyethylene terephthalate film (thickness 25 μm) was prepared as the base material layer, and one surface thereof was subjected to corona treatment.

[0081] <First Adhesive Layer (Thickness 4 μm)> A polyurethane-based adhesive (manufactured by Toyo Ink Co., Ltd.) in which an adduct-based curing agent of tolylene diisocyanate was blended with a polyester polyol-based main agent was used.

[0082] <First Corrosion Prevention Treatment Layer (on the side of the base material layer) and Second Corrosion Prevention Treatment Layer (on the side of the sealant layer)> (CL-1): Using an aqueous phosphoric acid solution with a concentration of 1% by mass as a solvent, a water-soluble phenolic resin (manufactured by Sumitomo Bakelite Co., Ltd.) adjusted to a solid content concentration of 1% by mass was used, and chromium fluoride (CrF3) was adjusted to a concentration such that the amount of Cr present in the final dried film was 10 mg / m 2 and a chemical conversion treatment agent was used. (CL-2): "Sodium polyphosphate-stabilized cerium oxide sol" adjusted to a solid content concentration of 10% by mass using distilled water as the solvent was used. The sodium polyphosphate-stabilized cerium oxide sol was obtained by blending 10 parts by mass of the Na salt of phosphoric acid with respect to 100 parts by mass of cerium oxide. (CL-3): A composition consisting of 90% by mass of "polyallylamine (manufactured by Nitto Boseki Co., Ltd.)" adjusted to a solid content concentration of 5% by mass using distilled water as the solvent and 10% by mass of "polyglycerol polyglycidyl ether (manufactured by Nagase ChemteX Corporation)" was used.

[0083] <Barrier layer (thickness 40 μm)> Annealed and degreased soft aluminum foil (manufactured by Toyo Aluminum Co., Ltd., "8079 material") was used.

[0084] <Second adhesive layer> An epoxy-based adhesive (ADEKA EP4100 / EH4602 = 100 / 25 (mass ratio)) was diluted with ethyl acetate to a solid content of 30% and used. This was applied to the surface of the barrier layer (soft aluminum foil) so that the coating amount after drying was 3 g / m 2 After drying at 80°C for 1 minute, the barrier layer and the sealant film were laminated. Then, aging was performed at 120°C for 3 hours.

[0085] <Sealant layer> To form the sealant layer, the following materials were prepared. [Base resin] · Polyester resin 1: A copolymer of terephthalic acid as the acid component and ethylene glycol as the glycol component · Polyester resin 2: A copolymer of terephthalic acid as the acid component and ethylene glycol and butanediol as the glycol components · Polyester resin 3: A copolymer of terephthalic acid and isophthalic acid as the acid components and ethylene glycol, butanediol, and neopentyl glycol as the glycol components · Polyester resin 4: Copolymer of terephthalic acid as an acid component and ethylene glycol and 1,4 - cyclohexanedimethanol as glycol components · Polyester resin 5: Copolymer of terephthalic acid and isophthalic acid as acid components and butanediol and hexanediol as glycol components · Polyester resin 6: Copolymer of terephthalic acid and isophthalic acid as acid components and butanediol and hexanediol as glycol components (with a higher proportion of butanediol than polyester resin 5) · Polyester resin 7: Copolymer of naphthalenedicarboxylic acid as an acid component and 1,4 - cyclohexanedimethanol as a glycol component · Polyester resin 8: Copolymer of terephthalic acid and isophthalic acid as acid components and ethylene glycol and hexanediol as glycol components · Polyolefin resin 1: Amide - modified polyethylene · Polyolefin resin 2: Random polypropylene [Plasticizer] · Glycol diester: Blended in an amount of 10 parts by mass as needed with respect to 100 parts by mass of the base resin material [Hydrogen sulfide absorbent] · Zinc oxide: Blended in an amount of 3 parts by mass as needed with respect to 100 parts by mass of the base resin material

[0086] [Fabrication of exterior material]< (Example 1) First, the first and second corrosion - prevention treatment layers were provided on the barrier layer by the following procedure. (CL - 1) was applied to both surfaces of the barrier layer by microgravure coating so that the dry coating amount was 30 mg / m 2 and baked at 200 °C in a drying unit (this treatment is called "chemical conversion treatment").

[0087] Next, the side of the first corrosion prevention treatment layer of the barrier layer was attached to the base material layer using a polyurethane-based adhesive (first adhesive layer) by the dry lamination method. Also, the side of the second corrosion prevention treatment layer of the barrier layer was attached to the sealant layer (thickness: 80 μm) using a polyurethane-based adhesive (second adhesive layer) by the dry lamination method. Through these steps, the exterior material according to Example 1 was obtained. The composition of the sealant layer was as follows. · Polyester resin 1: 100 parts by mass · Plasticizer: 10 parts by mass · Hydrogen sulfide adsorbing substance: 3 parts by mass

[0088] (Example 2) An exterior material was produced in the same manner as in Example 1, except that (CL-2) and (CL-3) were used to form the first and second corrosion prevention treatment layers instead of (CL-1). That is, (CL-2) was applied to both sides of the barrier layer by microgravure coating so as to have a dry coating amount of 70 mg / m 2 and baked at 200 °C in a drying unit. Next, (CL-3) was applied to the obtained layer by microgravure coating so as to have a dry coating amount of 20 mg / m 2 to form a composite layer composed of (CL-1) and (CL-2) as the first and second corrosion prevention treatment layers (this treatment is referred to as "composite treatment"). This composite layer exhibits corrosion prevention performance by compounding two types of (CL-2) and (CL-3).

[0089] (Example 3) An exterior material was produced in the same manner as in Example 2, except that a sealant material containing polyester resin 2 (plasticizer content: 10 parts by mass, hydrogen sulfide absorbent content: 3 parts by mass) was used to form the sealant layer instead of polyester resin 1.

[0090] (Example 4) An exterior material was produced in the same manner as in Example 2, except that no hydrogen sulfide absorbent was blended in the sealant material.

[0091] (Example 5) An exterior material was produced in the same manner as in Example 1, except that the barrier layer was not subjected to a corrosion prevention treatment and the sealant material did not contain a hydrogen sulfide absorbent.

[0092] (Example 6) An exterior material was produced in the same manner as in Example 1, except that the barrier layer was not subjected to a corrosion prevention treatment and polyester resin 3 (plasticizer content: 0 parts by mass, hydrogen sulfide absorbent content: 0 parts by mass) was used as the sealant material.

[0093] (Example 7) An exterior material was produced in the same manner as in Example 2, except that polyester resin 3 was used instead of polyester resin 1 and no plasticizer was blended.

[0094] (Example 8) An exterior material was produced in the same manner as in Example 7, except that polyester resin 4 was used instead of polyester resin 3.

[0095] (Example 9) An exterior material was produced in the same manner as in Example 7, except that polyester resin 5 was used instead of polyester resin 3.

[0096] (Example 10) An exterior material was produced in the same manner as in Example 7, except that polyester resin 6 was used instead of polyester resin 3.

[0097] (Example 11) An exterior material was produced in the same manner as in Example 7, except that polyolefin resin 1 was used instead of polyester resin 3.

[0098] (Example 12) An exterior material was produced in the same manner as in Example 2, except that the barrier layer and the sealant layer were bonded together by a thermal lamination method instead of a dry lamination method. The thermal lamination method was carried out as follows. That is, a laminate of a base material layer / first adhesive layer / first corrosion prevention treatment layer / barrier layer / second corrosion prevention treatment layer was set at the unwinding section of an extrusion laminator, and the material of the sealant layer was extruded onto the second corrosion prevention treatment layer under processing conditions of 270 ° C and 100 m / min. The laminate thus obtained was wound around a roll heated to 220 ° C and conveyed, and through a step of subjecting the laminate to a heat treatment at 220 ° C for about 0.5 seconds, an exterior material (base material layer / first adhesive layer / first corrosion prevention treatment layer / barrier layer / second corrosion prevention treatment layer / sealant layer) was obtained.

[0099] (Example 13) An exterior material was produced in the same manner as in Example 7, except that a sealant material containing both polyester resin 1 and polyester resin 7 was used instead of polyester resin 3. The composition of the sealant material was as follows. · Polyester resin 1: 50 parts by mass · Polyester resin 7: 50 parts by mass · Hydrogen sulfide adsorbent: 3 parts by mass

[0100] (Comparative Example 1) An exterior material was produced in the same manner as in Example 7, except that a sealant material containing polyester resin 7 was used instead of polyester resin 3. The composition of the sealant material was as follows. · Polyester resin 7: 100 parts by mass · Hydrogen sulfide adsorbent: 3 parts by mass

[0101] (Comparative Example 2) An exterior material was produced in the same manner as in Example 2, except that a plasticizer was not blended in the sealant material.

[0102] (Comparative Example 3) An exterior material was produced in the same manner as in Example 7, except that polyester resin 8 was used instead of polyester resin 3.

[0103] (Comparative Example 4) An exterior material was produced in the same manner as in Example 12, except that polyolefin resin 2 was used instead of polyester resin 1 and no hydrogen sulfide adsorbent was blended.

[0104] <Evaluation> The following evaluation tests were conducted on the exterior materials obtained in the examples and comparative examples.

[0105] [Tan δ of the sealant layer] The obtained exterior material was immersed in an aqueous sodium hydroxide solution, and a film consisting only of the sealant layer was taken out by dissolving the barrier layer. Subsequently, the taken-out film was cut into a width of 10 mm (TD) and a length of 30 mm (MD) to prepare a measurement sample, and the distance between the chucks was held at 20 mm. According to the method in accordance with JIS K7244-4, using a dynamic viscoelasticity apparatus (manufactured by SII, trade name: DMS6100), measurement was carried out under the following conditions, and the loss tangent tan δ was calculated from the loss elastic modulus E'' and the storage elastic modulus E'. Also, from the obtained tan δ profile, the temperature of the sub-dispersion peak γ and the temperature of the main dispersion peak α were determined. The results are shown in Table 1 and Table 2. ·Peeling mode: Tensile ·Temperature increase rate: 2 °C / min ·Temperature range: -100 to 120 °C ·Frequency: 1.0 Hz

[0106] [Initial seal strength] The exterior material was cut to obtain a film of 60 mm × 120 mm. This was folded in half and heat-sealed at 220 °C, 0.5 MPa, and 3 seconds with a seal bar having a width of 10 mm on one side. Then, the heat-sealed portion was cut to a width of 15 mm to obtain a measurement sample (see Figure 5). The seal strength (T-shaped peel strength) was measured using a testing machine (manufactured by INSTRON). The test was carried out at room temperature (23 °C) and a peel rate of 50 mm / min in accordance with JIS K6854. Based on the results, evaluation was carried out according to the following criteria. The results are shown in Table 1 and Table 2. A: Burst strength is 50 N / 15 mm or more B: Burst strength is 40 N / 15 mm or more and less than 50 N / 15 mm C: Burst strength is 35 N / 15 mm or more and less than 40 N / 15 mm D: Burst strength is less than 35 N / 15 mm

[0107] [High-temperature seal strength] The exterior material was cut to obtain a 60 mm × 120 mm film. This was folded in two, and one side was heat-sealed at 220°C, 0.5 MPa, for 3 seconds with a 10 mm-wide seal bar. The heat-sealed part was cut to a width of 15 mm, left standing in a 150°C environment for 5 minutes, and then the seal strength (T-peel strength, peel rate 50 mm / min) was measured in a 150°C environment. Based on the results, evaluation was carried out according to the following criteria. The results are shown in Table 1 and Table 2. A: Burst strength is 35 N / 15 mm or more B: Burst strength is 30 N / 15 mm or more and less than 35 N / 15 mm C: Burst strength is 20 N / 15 mm or more and less than 30 N / 15 mm D: Burst strength is less than 20 N / 15 mm

[0108] [Seal strength after hydrogen sulfide exposure (at room temperature environment)] The exterior material was cut to obtain a 60 mm × 120 mm film. This was folded in two, and one side was heat-sealed at 220°C, 0.5 MPa, for 3 seconds with a 10 mm-wide seal bar. The heat-sealed part was cut to a width of 15 mm, left standing in a room temperature environment with a hydrogen sulfide concentration of 20 ppm for 72 hours, and then the seal strength (T-peel strength, peel rate 50 mm / min) was measured in a room temperature environment. Based on the results, evaluation was carried out according to the following criteria. The results are shown in Table 1 and Table 2. A: Burst strength is 50 N / 15 mm or more B: Burst strength is 40 N / 15 mm or more and less than 50 N / 15 mm C: Burst strength is 35 N / 15 mm or more and less than 40 N / 15 mm D: Burst strength is less than 35 N / 15 mm

[0109] [Seal strength after hydrogen sulfide exposure (at 150°C environment)] The exterior material was cut to obtain a film of 60 mm × 120 mm. This was folded in two, and one side was heat-sealed at 220 °C, 0.5 MPa for 3 seconds with a seal bar of 10 mm width. The heat-sealed part was cut to a width of 15 mm and left standing for 72 hours in a room-temperature environment with a hydrogen sulfide concentration of 20 ppm. Then, after leaving it standing in a 150 °C environment for 5 minutes, the seal strength (T-peel strength, peel rate 50 mm / min) was measured in a 150 °C environment. Based on the results, it was evaluated according to the following criteria. The results are shown in Table 1 and Table 2. A: The burst strength is 35 N / 15 mm or more B: The burst strength is 30 N / 15 mm or more and less than 35 N / 15 mm C: The burst strength is 20 N / 15 mm or more and less than 30 N / 15 mm D: The burst strength is less than 20 N / 15 mm

[0110]

Table 1

[0111]

Table 2

[0112] In Tables 1 and 2, those without a D in the evaluation results can be said to have excellent overall quality. For Examples 1 to 13, the evaluation of the seal strength was A to C. In contrast, for Comparative Examples 1 to 4, part of the evaluation of the seal strength was D. Specifically, for Comparative Example 1, the evaluation of the seal strength at room temperature (initial and after hydrogen sulfide exposure) was D. This is presumably because the temperature of the sub-dispersion peak γ was higher than the range of -130°C to -50°C and the temperature of the main dispersion peak α was also higher than the range of 30°C to 130°C. For Comparative Example 2 as well, the evaluation of the seal strength at room temperature (initial and after hydrogen sulfide exposure) was D. This is presumably because the temperature of the sub-dispersion peak γ was higher than the range of -130°C to -50°C. For Comparative Example 3, the evaluation of the seal strength in an environment at 150°C both before and after hydrogen sulfide exposure was D. This is presumably because the temperature of the sub-dispersion peak γ was lower than the range of -130°C to -50°C. For Comparative Example 4 as well, the evaluation of the seal strength in an environment at 150°C both before and after hydrogen sulfide exposure was D. This is presumably because the temperature of the sub-dispersion peak γ was lower than the range of -130°C to -50°C and the temperature of the main dispersion peak α was also lower than the range of 30°C to 130°C.

Description of Reference Numerals

[0113] 10... Exterior material for power storage device, 11... Base material layer, 12... First adhesive layer, 13... Barrier layer, 14... Corrosion prevention treatment layer, 16... Sealant layer, 16a... First resin layer, 16b... Second resin layer, 16c... Third resin layer, 17... Second adhesive layer, 30... Metal terminal, 40... Resin film for terminal, 50... Power storage device main body, 100... Power storage device

Claims

[Claim 1] A base layer; A barrier layer; A sealant layer; A laminate structure having at least the following in this order, The sealant layer has at least one minor dispersion peak γ in the range of −130° C. to −50° C. in a profile of loss tangent tan δ obtained by dynamic viscoelasticity measurement under a condition of 1.0 Hz.

Images