JP2021157865A - Terminal film for power storage device - Google Patents

Abstract

To provide a terminal film for power storage devices, capable of achieving, at a sufficiently high level, both seal strength under high temperatures and initial seal strength under a room temperature environment.SOLUTION: A terminal film 40 for power storage devices is disposed to cover a part of the outer peripheral surface of a metal terminal 30 that is electrically connected to a power storage device body 10 constituting a power storage device 100. The terminal film is composed of a resin composition including polyolefin, as a first resin, and at least one resin selected from among polyester, polyamide, polycarbonate and polyphenylene ether, as a second resin.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to a terminal film for a power storage device arranged so as to cover a part of the outer peripheral surface of a metal terminal electrically connected to the main body of the power storage device.

As the power storage device, for example, a secondary battery such as a lithium ion battery, a nickel hydrogen battery, and a lead storage battery, and an electrochemical capacitor such as an electric double layer capacitor are known. Further miniaturization of power storage devices is required due to miniaturization of portable devices or restrictions on installation space, and lithium ion batteries having high energy density are attracting attention. Conventionally, metal cans have been used as exterior materials used in lithium-ion batteries, but multilayer films that are lightweight, have high heat dissipation, and can be manufactured at low cost are now being used.

A lithium ion battery using the 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.) to prevent the ingress of moisture into the battery. In a laminated lithium-ion battery, for example, a recess is formed in a part of the exterior material by cold molding, the battery contents are housed in the recess, the remaining part of the exterior material is folded back, and the edge portion is heat-sealed. Manufactured by sealing with (see, for example, Patent Document 1).

Laminated lithium-ion batteries include a current take-out terminal (sometimes referred to as a "tab lead"). A terminal film (sometimes called a "tab sealant") may be placed so as to cover a part of the outer circumference of the current take-out terminal for the purpose of improving the adhesion between the current take-out terminal and the exterior material. (See, for example, Patent Documents 2 to 4).

Japanese Unexamined Patent Publication No. 2013-101765 Japanese Unexamined Patent Publication No. 2008-4316 Japanese Unexamined Patent Publication No. 2010-218766 Japanese Unexamined Patent Publication No. 2009-259739

By the way, as a next-generation battery of a lithium ion battery, research and development of a power storage device called an all-solid-state battery is being carried out. The all-solid-state battery has a feature that it does not use an organic electrolytic solution as an electrolytic substance but uses a solid electrolyte. Lithium-ion batteries cannot be used under temperature conditions higher than the boiling point temperature of the electrolytic solution (about 80 ° C.), whereas all-solid-state batteries can be used under temperature conditions exceeding 100 ° C. Lithium ion conductivity can be increased by operating under high temperature conditions (eg 100-150 ° C.).

However, when a laminated all-solid-state battery is manufactured by using the above-mentioned laminate as the exterior material, the sealability of the all-solid-state battery package is improved due to insufficient heat resistance of the terminal film. It may be insufficient. On the other hand, from the viewpoint of ensuring the heat seal strength in a high temperature environment, if a resin having high heat resistance is used for the terminal film to be fused by the heat seal, it is operated in a high temperature environment and then returned to room temperature. The present inventors have found that the problem of reduced heat seal strength in an environment arises.

Therefore, the present disclosure provides a terminal film for a power storage device that can secure excellent heat-sealing strength in a high-temperature environment and can secure excellent heat-sealing strength in a room temperature environment after being exposed to a high-temperature environment.

The terminal film for a power storage device (hereinafter, also simply referred to as “terminal film”) according to one aspect of the present disclosure covers a part of the outer peripheral surface of a metal terminal electrically connected to the main body of the power storage device constituting the power storage device. The terminal film for a power storage device arranged as described above includes a polyolefin as a first resin and at least one resin selected from polyester, polyamide, polycarbonate, and polyphenylene ether as a second resin. Consists of a resin composition containing ,.

By using the second resin, the heat seal strength of the terminal film in a high temperature environment can be improved. However, the present inventors have found that when the second resin is used alone, the heat seal strength in a room temperature environment decreases, and it becomes difficult to secure excellent heat seal strength in both environments. rice field. The second resin is a resin having high heat resistance, and although its performance when used in a high temperature environment has been investigated, the heat seal strength in a room temperature environment is before and after exposure to a high temperature environment. Until now, sufficient consideration has not been given to changes. Since the all-solid-state battery is repeatedly placed in a high temperature environment when used and in a room temperature environment when not in use, it is necessary that the heat seal strength of the terminal film does not deteriorate in both use environments. Therefore, as a result of diligent studies, the present inventors have been able to suppress a decrease in heat seal strength in both a high temperature environment and a room temperature environment by using the first resin in combination with the second resin. I found out what I could do. That is, according to the terminal film for a power storage device, excellent heat seal strength can be ensured in a high temperature environment by using a specific first resin and a specific second resin in combination as the material of the terminal film. Excellent heat seal strength can be ensured even in a room temperature environment.

The terminal film for a power storage device preferably contains a modified polyolefin in which a polar group capable of reacting with polyester, polyamide, polycarbonate, or polyphenylene ether is modified.
Further, in the terminal film for the power storage device, it is preferable that the modified polyolefin is modified with maleic anhydride.
The compatibility between the first resin and the second resin is not always good, and the dispersibility may be insufficient, so that the above-mentioned combined effect may not be sufficiently obtained. On the other hand, when the first resin contains a modified polyolefin having a polar group capable of reacting with the second resin, the compatibility between the first resin and the second resin is enhanced and the dispersibility is improved. Can be done. As a result, the synergistic effect of the combined use of the first resin and the second resin can be more sufficiently obtained, more excellent heat seal strength can be ensured in a high temperature environment, and more excellent in a room temperature environment. The heat seal strength can be secured. Further, when the modified polyolefin is a polyolefin modified with maleic anhydride, the above effect can be more sufficiently obtained.

Here, the first resin may contain the above-mentioned modified polyolefin and a polyolefin having no polar group capable of reacting with the second resin (unmodified polyolefin). Since modified polyolefins tend to decrease in melting point and molecular weight due to modification, the decrease in heat seal strength in a high temperature environment can be suppressed by using a combination of ordinary polyolefins (unmodified polyolefins). .. When the modified polyolefin and the unmodified polyolefin are used in combination, the modified polyolefin plays a role as a compatibilizer, and the dispersibility between the unmodified polyolefin and the second resin can be improved.

The terminal film for the power storage device has a crystallinity of 10% when the polyester or polyamide contained in the terminal film is heat-sealed at 260 ° C., 0.5 MPa for 3 seconds and then cooled at room temperature. As mentioned above, it is preferably less than 70%. When the crystallinity of the polyester and / or polyamide measured by the above method is within the above range, the heat seal strength in a high temperature environment can be further improved, and the flexibility of the terminal film can be further improved.

The terminal film for a power storage device preferably contains a hydrogen sulfide adsorbent in the terminal film. This hydrogen sulfide adsorbent may be contained in the terminal film, or may be contained in another layer when the terminal film has a multilayer structure. In the all-solid-state battery, for example, a sulfide-based electrolyte, an oxide-based electrolyte, or an organic polymer-based electrolyte is used as the electrolyte. Of these, when a sulfide-based electrolyte is used, hydrogen sulfide is generated when water is mixed inside the cell, and there is a concern that the adhesion between the outer peripheral surface of the terminal and the terminal film may be reduced. Since the terminal film contains a hydrogen sulfide adsorbent, excellent sealing strength at room temperature and high temperature can be maintained even after exposure to hydrogen sulfide.

According to the present disclosure, there is provided a terminal film for a power storage device capable of achieving both the sealing strength at high temperature and the initial sealing strength at room temperature at a sufficiently high level.

It is a perspective view which shows an example of an all-solid-state battery. It is sectional drawing which shows typically an example of the exterior material for a power storage device. It is sectional drawing which shows typically the structure of the sealant layer provided in the exterior material for a power storage device. It is sectional drawing in the IV-IV direction shown in FIG. 1, and is sectional drawing which shows typically the structure of the tab (terminal film and metal terminal) of an all-solid-state battery. It is sectional drawing which shows typically the example of the structure of the terminal film. It is a top view which shows typically the evaluation sample prepared in an Example and a comparative example.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the embodiments described below. Further, in the embodiment shown below, technically preferable limitation is made for carrying out the invention, but this limitation is not an essential requirement of the present invention.

<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, an all-solid-state battery is illustrated as an example, and the following description will be given. The power storage device having the configuration shown in FIG. 1 may be referred to as a battery pack or a battery cell.

The power storage device 100 is an all-solid-state battery, and includes a power storage device main body 50, an exterior material 10, a pair of metal terminals 30, and a terminal film (tab sealant) 40. The power storage device main body 50 is a battery main body that charges and discharges. The exterior material 10 covers the surface of the power storage device main body 50 and is arranged so as to come into contact with a part of the terminal film 40.

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

(Sealant layer)
The sealant layer 16 is a layer that imparts sealing properties to the exterior material 10 by heat sealing, and is a layer that is arranged inside and heat-sealed (heat-sealed) when the power storage device is assembled.

As the sealant layer 16, for example, a thermoplastic resin such as polyolefin, polyamide, polyester, polycarbonate, polyphenylene ether, polyacetal, polystyrene, polyvinyl chloride, or polyvinyl acetate can be used, and from the viewpoint of heat resistance and seal suitability, it can be used. It is preferable to use polyolefin, polyamide, or polyester. When directly laminating the barrier layer without using an adhesive, it is preferable to use a layer in which at least one layer in contact with the barrier layer is modified with an acid or glycidyl.

Examples of the polyolefin-based resin include low-density, medium-density and high-density polyethylene; ethylene-α-olefin copolymer; polypropylene; and propylene-α-olefin copolymer. When it is a copolymer, the polyolefin resin may be a block copolymer or a random copolymer.

Examples of the polyester-based resin include polyethylene terephthalate (PET) and polybutylene terephthalate (PBT). These polyester resins may be used alone or in combination of two or more. Moreover, you may use the thing which copolymerized arbitrary acid and glycol.

Further, similarly to the terminal film described later, a resin composition containing polyolefin as the first resin and at least one resin selected from polyester, polyamide, polycarbonate, and polyphenylene ether as the second resin is used. You may.

Add antioxidants, slip agents, flame retardants, anti-blocking agents, light stabilizers, dehydrating agents, tackifiers, crystal nucleating agents, plasticizers, etc. to impart sealing properties, heat resistance, and other functionality. You may.

The melting peak temperature of the sealant layer 16 varies depending on the application, but in the case of an exterior material for an all-solid-state battery, it is preferably 160 to 280 ° C. because heat resistance is improved.

The temperature at which the sub-dispersion peak γ and the main dispersion peak α of the sealant layer 16 appear is, for example, the structure of the base resin material contained in the sealant layer 16, the draw ratio of the sealant layer 16, or the additive (for example, a plasticizer). It can be controlled by the blending amount. The sealant layer 16 contains additives as needed. Examples of the additive include a plasticizer, an antioxidant, a slip agent, a flame retardant, an AB agent, a light stabilizer, a dehydrating agent, and a tackifier.

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

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 study by the present inventors, in general PET (copolymer of terephthalic acid and ethylene glycol), the temperature at which the subdispersion peak γ exists is out of the range of −130 ° C. to −50 ° C., and at room temperature. Seal strength is insufficient. When the plasticizer is not blended in the sealant layer 16, the sealant layer 16 preferably contains a polyester resin in which two or more kinds of glycol components are copolymerized with one kind of acid component.

Examples of the polyolefin resin include polyethylene and polypropylene resins. Since commonly used polyolefin resins have poor heat resistance, it is preferable to use polyethylene, polypropylene, or the like in which an amide is modified.

Examples of the polyamide resin include nylon 6 and nylons 6 and 6.

From the viewpoint of adjusting the temperature at which the sub-dispersion peak γ and the main dispersion peak α of the sealant layer 16 appear, the sealant layer 16 preferably contains a plasticizer. As the plasticizer, for example, an ester compound can be used. Specific examples include glycol diesters, adipates, phthalates, diacetylmonoacylglycerol derivatives, and esters having an ether skeleton. Although it depends 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 excess plasticizer is added to the sealant layer 16, the temperature at which the sub-dispersion peak γ and the main dispersion peak α appear is excessively lowered, and the cohesive force tends to be lowered.

The sealant layer 16 may have a single-layer structure or a multi-layer structure having two or more layers (see FIGS. 3A to 3C). 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 secure the sealing property and the insulating property, while when it is 300 μm or less, the cell volume can be secured.

FIG. 3B 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 a material different from that of the second resin layer 16b, or may have a thickness different from that of the second resin layer 16b. The thickness of the first resin layer 16a and the second resin layer 16b is, for example, 5 to 300 μm and may be 20 to 200 μm, respectively. As shown in FIG. 3C, the sealant layer 16 has a three-layer structure and may further include a third resin layer 16c.

When the electrolyte of the all-solid-state battery is a sulfide-based electrolyte, the sealant layer 16 preferably contains a hydrogen sulfide adsorbent. Since the sealant layer 16 contains a hydrogen sulfide adsorbent, excellent sealing strength at room temperature and high temperature can be maintained even after exposure to hydrogen sulfide. As the hydrogen sulfide adsorbent, a material having the ability to absorb or adsorb hydrogen sulfide can be used. Specific examples thereof include zinc oxide, amorphous metal silicate, hydroxide of zirconium and lanthanoid elements, tetravalent metal phosphate, potassium permanganate, sodium permanganate, aluminum oxide, iron hydroxide, and sulfuric acid. Examples thereof include silver, silver acetate, isocyanate compounds, aluminum silicate, potassium aluminum sulfate, zeolites, activated carbons, amine compounds and ionomers.

The content of the hydrogen sulfide adsorbent in the sealant layer 16 is preferably 1 to 50% by mass, more preferably 2 to 25% by mass, still more preferably 5 to 15% by mass, based on the mass of the sealant layer 16. Is. When the content of the hydrogen sulfide adsorbent in the sealant layer 16 is 1% by mass or more, the hydrogen sulfide adsorption effect is exhibited, while when it is 50% by mass or less, both the adhesion of the sealant layer 16 and the suitability of the sealant are compatible. can. When the sealant layer 16 has a multi-layer structure, all or a part of the sealant layer 16 may contain a hydrogen sulfide adsorbent. The 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 at least the sealant layer 16 may contain a hydrogen sulfide adsorbent. It preferably contains a hydrogen sulfide adsorbent.

(Base layer)
The base material layer 11 imparts heat resistance in the sealing process when manufacturing the power storage device, and plays a role of suppressing the generation of pinholes that may occur during molding and distribution. In particular, in the case of an exterior material of a power storage device for large-scale applications, scratch resistance, chemical resistance, insulation and the like can be imparted.

The base material layer 11 is preferably a layer made of a resin film formed of an insulating resin. Examples of the resin film include stretched or unstretched films such as polyester film, polyamide film, polypropylene film and polyphenylene sulfide film. The base material layer 11 may be a single-layer film composed of any one of these resin films, or may be a laminated film composed of two or more of these resin films.

Among these, as the base material layer 11, a polyester film and a polyamide film are preferable, and a polyamide film is more preferable, because the base material layer 11 is excellent in moldability. These films are preferably biaxially stretched films. Examples of the polyester resin constituting the polyester film include polyethylene terephthalate. 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, 10, polymethoxylylene adipamide (MXD6), and nylon 11. , Nylon 12 and the like. Among these, nylon 6 (ONy) is preferable from the viewpoint of excellent heat resistance, piercing strength and impact strength.

Examples of the stretching method in the biaxially stretched film include a sequential biaxial stretching method, a tubular biaxial stretching method, and a simultaneous biaxial stretching method. The biaxially stretched film is preferably stretched by the tubular biaxial stretching method from the viewpoint of obtaining more excellent deep drawing moldability.

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 the insulating property 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.

(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 obtained by reacting a main agent such as a polyester polyol, a polyether polyol, an acrylic polyol, or a carbonate polyol with a bifunctional or higher functional isocyanate compound. Examples include resin. The various polyols described above can be used alone or in combination of two or more, depending on the function and performance required for the exterior material. Further, various other additives and stabilizers may be added to the above-mentioned polyurethane resin depending on the performance required for the adhesive.

The thickness of the first adhesive layer 12 is not particularly limited, but is preferably 1 to 10 μm, preferably 3 to 7 μm, from the viewpoint of obtaining desired adhesive strength, followability, processability, and the like. More preferred.

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

As the aluminum foil, a soft aluminum foil that has been subjected to a quenching treatment can be particularly preferably used from the viewpoint of imparting a desired ductility during molding, but further pinhole resistance and ductility during molding are imparted. It is more preferable to use an aluminum foil containing iron for the purpose of making the foil. 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. An untreated aluminum foil may be used, but it is preferable to use a degreased aluminum foil. When the aluminum foil is degreased, only one side of the aluminum foil may be degreased, or both sides may be degreased.

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

(Corrosion prevention treatment layer)
The corrosion prevention treatment layer 14 is a layer provided to prevent corrosion of the barrier layer 13. The corrosion prevention treatment layer 14 is formed by, for example, a degreasing treatment, a hydrothermal transformation treatment, an anodic oxidation treatment, a chemical conversion treatment, or a combination of these treatments.

Examples of the degreasing treatment include acid degreasing and alkaline degreasing. Examples of the acid degreasing include a method in which an inorganic acid such as sulfuric acid, nitric acid, hydrochloric acid, or hydrofluoric acid is used alone, or a mixed solution thereof is used. Further, as the acid degreasing, by using an acid degreasing agent in which a fluorine-containing compound such as monosodium difluoride is dissolved in the above-mentioned inorganic acid, the degreasing effect of aluminum is particularly effective when an aluminum foil is used for the barrier layer 13. It is effective in terms of corrosion resistance because it can form an immobile aluminum fluoride. Examples of the alkaline degreasing include a method using sodium hydroxide and the like.

Examples of the hot water transformation treatment include a boehmite treatment in which an aluminum foil is immersed in boiling water to which triethanolamine is added. Examples of the anodizing treatment include alumite treatment.

Examples of the chemical conversion treatment include a dipping type and a coating type. Examples of the immersion type chemical conversion treatment include chromate treatment, zirconium treatment, titanium treatment, vanadium treatment, molybdenum treatment, calcium phosphate treatment, strontium hydroxide treatment, cerium treatment, ruthenium treatment, and various chemical conversion treatments composed of a mixed phase thereof. Be done. On the other hand, as a coating type chemical conversion treatment, a method of coating a coating agent having corrosion prevention performance on the barrier layer 13 can be mentioned.

Of these corrosion prevention treatments, when at least a part of the corrosion prevention treatment layer is formed by any of the hydrothermal transformation treatment, the anodic oxidation treatment, and the chemical conversion treatment, it is preferable to perform the above-mentioned degreasing treatment in advance. When a degreased metal foil such as a metal foil that has undergone an annealing step is used as the barrier layer 13, it is not necessary to perform the degreasing treatment again in forming the corrosion prevention treatment layer 14.

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.

Among the above treatments, particularly in the hydrothermal transformation treatment and the anodic oxidation treatment, the surface of the aluminum foil is dissolved by the treatment agent to form aluminum compounds (bemite, alumite) having excellent corrosion resistance. Therefore, a co-continuous structure is formed from the barrier layer 13 using the aluminum foil to the corrosion prevention treatment layer 14, and 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 which is not included in the definition of chemical conversion treatment. As this method, for example, a sol of a rare earth element oxide such as cerium oxide having an average particle size of 100 nm or less is used as a material having an anticorrosion effect (inhibitor effect) of aluminum and also being environmentally suitable. The method to be used 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 with a general coating method.

Examples of the rare earth element oxide sol include sol using various solvents such as water-based, alcohol-based, hydrocarbon-based, ketone-based, ester-based, and ether-based solvents. Of these, 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 salts thereof, and organic acids such as acetic acid, apple acid, ascorbic acid and lactic acid are usually dispersed and stabilized in order to stabilize the dispersion. Used as an agent. Among these dispersion stabilizers, phosphoric acid, in particular, is used in the exterior material 10 to (1) stabilize the dispersion of the sol, and (2) improve the adhesion to the barrier layer 13 by utilizing the aluminum chelating ability of phosphoric acid. (3) It is expected that the cohesive force of the corrosion prevention treatment layer 14 (oxide layer) will be improved by easily causing dehydration condensation of phosphoric acid even at a low temperature.

Since the corrosion prevention treatment layer 14 formed by the rare earth element oxide sol is an aggregate of inorganic particles, the cohesive force of the layer itself may decrease even after the drying cure step. Therefore, the corrosion prevention treatment layer in this case is preferably composited with the following anionic polymer or cationic polymer in order to supplement the cohesive force.

The corrosion prevention treatment layer is not limited to the above-mentioned layer. For example, it may be formed by using a treatment agent in which a phosphoric acid and a chromium compound are mixed in a resin binder (aminophenol or the like), such as coating type chromate which is a known technique. By using this treatment agent, it is possible to obtain a layer having both a corrosion prevention function and adhesion. In addition, 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 preliminarily liquefied is used for both corrosion prevention function and adhesion. It can be a layer that combines.

Mass per unit area of the corrosion prevention treatment layer multilayer structure, it is either single-layer structure, preferably 0.005~0.200g / ^{m 2,} more preferably 0.010~0.100g / ^{m 2} .. When the mass per unit area is 0.005 g / m ² or more, it is easy to impart the corrosion prevention function to the barrier layer 13. Further, even 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 a rare earth element oxide sol is used, if the coating film is thick, curing due to heat during drying may be insufficient, and the cohesive force may be lowered. The thickness of the corrosion prevention treatment layer 14 can be converted from its specific gravity.

From the viewpoint of adhesion between the sealant layer and the barrier layer, the corrosion prevention treatment layer includes, for example, 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. , And may be a mode in which the barrier layer 13 is subjected to a chemical conversion treatment to be formed, and the barrier layer is formed by being subjected to a chemical conversion treatment and is formed.
The embodiment may include a cationic polymer.

(Second adhesive layer)
The second adhesive layer 17 is a layer for adhering the barrier layer 13 on which the corrosion prevention treatment layer 14 is formed and the sealant layer 16. For the second adhesive layer 17, a general adhesive for adhering the barrier layer 13 and the sealant layer 16 can be used.

When the corrosion prevention treatment layer 14 has a layer containing at least one polymer selected from the group consisting of the above-mentioned cationic polymer and anionic polymer, the second adhesive layer 17 is included in the corrosion prevention treatment layer 14. It is preferable that the layer contains a compound having a reactivity with the polymer (hereinafter, also referred to as “reactive compound”).

For example, when the corrosion protection treatment layer 14 contains a cationic polymer, the second adhesive layer 17 contains a compound that is reactive with the cationic polymer. When the corrosion protection treatment layer 14 contains an anionic polymer, the second adhesive layer 17 contains a compound that is reactive with the anionic polymer. 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 kinds of compounds, and may contain a compound having reactivity with both a cationic polymer and an anionic polymer. Here, "reactive" means forming a covalent bond with a cationic polymer or an anionic polymer. Further, the second adhesive layer 17 may further contain an acid-modified polyolefin resin.

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

Examples of these polyfunctional isocyanate compounds, glycidyl compounds, compounds having a carboxy group, and compounds having an oxazoline group include polyfunctional isocyanate compounds, glycidyl compounds, and carboxy groups exemplified above as cross-linking agents for forming a cationic polymer into a cross-linking structure. Examples thereof include a compound having a oxazoline group and a compound having an oxazoline group. Among these, a polyfunctional isocyanate compound is preferable because it has high reactivity with a cationic polymer and easily forms a crosslinked structure.

Examples of the compound having reactivity with the anionic polymer include at least one compound selected from the group consisting of a glycidyl compound and a compound having an oxazoline group. Examples of these glycidyl compounds and compounds having an oxazoline group include glycidyl compounds exemplified above as a cross-linking agent for forming a cationic polymer into a cross-linked structure, and compounds having an oxazoline group. Among these, the glycidyl compound is preferable because it has high reactivity with the anionic polymer.

When the second adhesive layer 17 contains an acid-modified polyolefin resin, it is preferable that the reactive compound is also reactive with the acidic group in the acid-modified polyolefin resin (that is, forms a covalent bond with the acidic group). As a result, the adhesiveness with the corrosion prevention treatment layer 14 is further enhanced. In addition, the acid-modified polyolefin resin has a crosslinked structure, and the solvent resistance of the exterior material 10 is further improved.

The content of the reactive compound is preferably equal to 10 times the equivalent amount of the acidic group in the acid-modified polyolefin resin. When the amount is equal to or more than the equal amount, the reactive compound sufficiently reacts with the acidic group in the acid-modified polyolefin resin. On the other hand, if the amount exceeds 10 times the equivalent amount, the cross-linking reaction with the acid-modified polyolefin resin has reached sufficient saturation, so that unreacted substances are present and there is a concern that various performances may be deteriorated. 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.

The acid-modified polyolefin resin is one in which an acidic group is introduced into the polyolefin resin. Examples of the acidic group include a carboxy group, a sulfonic acid group, an acid anhydride group and the like, and a maleic anhydride group and a (meth) acrylic acid group are particularly preferable. As the acid-modified polyolefin resin, for example, the same modified polyolefin resin used for the sealant layer 16 can be used.

Various additives such as flame retardants, slip agents, anti-blocking agents, antioxidants, light stabilizers, and tackifiers may be blended in the second adhesive layer 17.

As the adhesive forming the second adhesive layer 17, for example, a polyurethane resin or an epoxy group obtained by reacting a main agent such as a polyester polyol, a polyether polyol, an acrylic polyol, or a carbonate polyol with a bifunctional or higher isocyanate compound. Examples thereof include an epoxy resin in which an amine compound or the like is allowed to act on the main agent, which is preferable from the viewpoint of heat resistance.

The thickness of the second adhesive layer 17 is not particularly limited, but is preferably 1 to 10 μm, more preferably 2 to 7 μm, from the viewpoint of obtaining desired adhesive strength, processability, and the like.

[Metal terminal]
FIG. 4 is a cross-sectional view of the terminal film and the metal terminal shown in FIG. 1 in the IV-IV direction. Of the pair of metal terminals 30 and 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. Has been done. The pair of metal terminals 30, 30 extend 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.

As the material of the metal terminal 30, metal can be used. The metal to be the material of the metal terminal 30 may be determined in consideration of the structure of the power storage device main body 50, the materials of its constituent elements, and the like. 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 or nickel having a nickel plating layer formed on the surface.

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. Further, in the case of a large-sized all-solid-state battery for storage and in-vehicle use, the thickness of the metal terminal 30 can be appropriately set within the range of, for example, 100 to 500 μm.

[Terminal film]
As shown in FIG. 4, the terminal film 40 is arranged so as to cover a part of the outer peripheral surface of the metal terminal 30. By arranging the terminal film 40 between the metal terminal 30 and the exterior material 10, the sealing property and the insulating property of the power storage device 100 can be further achieved. The terminal film 40 has heat resistance equal to or higher than that of the sealant layer 16 and the base material layer 11 described above.

The terminal film 40 has a resin composition containing polyolefin as a first resin and at least one resin selected from polyester, polyamide, polycarbonate, and polyphenylene ether (hereinafter referred to as polyester or the like) as a second resin. It consists of things. The terminal film 40 has a single-layer structure or a multi-layer structure. When the terminal film 40 has a single-layer structure, the terminal film 40 is made of a resin layer 40a (see FIG. 5A). When the terminal film 40 has a multilayer structure, the terminal film 40 may include at least one resin layer (resin layer 40a) satisfying the above conditions (see FIGS. 5 (b) and 5 (c)). When the terminal film 40 has a multi-layer structure, it is preferable that all layers are made of the same resin material from the viewpoint of adhesion between adjacent layers.

The terminal film 40 preferably contains a modified polyolefin having a modified polar group capable of reacting with a second resin such as polyester. When the terminal film 40 includes the resin layer 40a having the above composition, the terminal film 40 can achieve both the sealing strength at high temperature and the initial sealing strength (sealing strength at room temperature) at a sufficiently high level. The resin constituting the terminal film 40 will be illustrated below.

(Polyolefin resin)
As the polyolefin resin, polyethylene (LDPE, LLDPE, HDPE), polypropylene (homo, block, random), polybutene and the like can be used. From the viewpoint of heat resistance and flexibility, polypropylene is preferably used, and block polypropylene is particularly preferable.

(Polyester resin)
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. However, it is preferable that the crystallinity is 10% or more and less than 70% after heat-sealing at 260 ° C.-0.5 Mpa-3s. This is because if the crystallinity of the polyester is too low, the high-temperature sealing strength is not sufficiently developed, and if it is too high, the flexibility tends to be poor. From the above tendency, it is more preferable to use polyester having a crystallinity of 15% or more and less than 50%. As the polyester resin, it is preferable to use a copolymer of these.

(Polyamide resin)
As the polyamide resin, nylons such as nylon 6, nylon 11, nylon 12, nylon 6 and 6 can be used. Moreover, you may use the aramid system which has an aromatic. Similar to polyester, the crystallinity is preferably 10% or more and less than 70%, more preferably 15% or more and less than 50% after heat sealing.

Further, since polycarbonate and polyphenylene ether are amorphous, there is no preferable range in crystallinity.

The polyester, polyamide, and other resins exemplified above may contain at least one, and may contain a plurality of them. In addition, each resin may be one kind or a blend of a plurality of kinds (for example, polyolefin may be a mixture of blocks and random).

(Modified polyolefin)
Examples of the functional group with which the second resin reacts include, for example, the following functional groups, but the functional groups are not limited thereto.
Polyester: terminal hydroxyl group, terminal carboxyl group, ester-bonded polyamide: terminal amino group, amide-bonded polycarbonate: terminal hydroxyl group, ester-bonded polyphenylene ether: terminal hydroxyl group

Examples of the modifying group that reacts with each of the above functional groups include the following.
-Polyester, polycarbonate: hydroxyl group, acid-modified (ester) group, aldehyde group, oxazoline group, glycidyl group, amide group, imino group-Polyamide reaction: hydroxyl group, acid-modified (ester) group, aldehyde group, glycidyl group-polyphenylene Ether reaction: Acid-modified (ester) group, oxazoline group, glycidyl group, amide group, imino group Specific examples include
Hydroxy group: Poval (Kuraray), Mercen H (Tosoh)
Glycidyl group: Modiper (NOF), LOTADER, BONDINE (Arkema) Amide group: APOLHYA (Arkema)
Imino group ・ ・ ・ Admer IP (Mitsui Chemicals)
Oxazoline group ・ ・ ・ Epocross (Nippon Shokubai)
Etc. can be exemplified as suitable ones.

Regarding acid modification, examples thereof include acid-modified poreolefins that are modified from any of unsaturated carboxylic acids, acid anhydrides of unsaturated carboxylic acids, and esters of unsaturated carboxylic acids.

Specifically, as unsaturated carboxylic acids, for example, acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, tetrahydrophthalic acid, bicyclo [2,2,1] hept-2-ene-5, 6-Dicarboxylic acid and the like can be mentioned.

Examples of the acid anhydride of the unsaturated carboxylic acid include maleic anhydride, itaconic anhydride, citraconic anhydride, tetrahydrophthalic anhydride, and bicyclo [2,2,1] hept-2-ene-5,6-dicarboxylic acid anhydride. Examples thereof include acid anhydrides of unsaturated carboxylic acids such as substances.

Examples of the ester of unsaturated carboxylic acid include methyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dimethyl maleate, monomethyl maleate, diethyl fumarate, dimethyl itacone, diethyl citraconate, and tetrahydrophthalic anhydride. Examples thereof include esters of unsaturated carboxylic acids such as dimethyl and dimethyl bicyclo [2,2,1] hept-2-ene-5,6-dicarboxylic acid.

As a specific product, for example, the following can be used, and it is preferable to use acid-modified maleic acid.
Maleic anhydride: Admer (Mitsui Chemicals), Modic (Mitsubishi Chemical), Toyo Tuck (Toyobo), Sun Stack (Sanyo Chemicals)
Carboxyl group: Nucrel, Hymilan (Mitsui / DuPont Polychemical) * Ionomer type can also be used.
Ester group: Evaflex (Mitsui / DuPont Polychemical), LOTADER, BONDINE, EVATANE (Arkema)

As the ratio of each resin in the terminal film 40, the ratio of polyolefin is more preferably 10 to 80 wt% from the viewpoint of the balance between the high temperature seal strength and the room temperature seal strength. Assuming that the total amount of polyolefin, polyester, etc. is 100 wt%, the proportion of polyester, etc. is preferably 90 to 20 wt%. The proportion of the modified polyolefin in the polyolefin is preferably 0.1 wt% to 100 wt%, more preferably 0.5 wt% to 40 wt%. If the amount added is too small, the reaction with polyester or polyamide will be difficult to proceed. Further, although there is no problem in performance at 100 wt%, when the melting point of the modified polyolefin is low, the high temperature seal strength may decrease, so it is more preferably 40 wt% or less.

When the terminal film 40 has a multi-layer structure, the resin layer 40a may be arranged on the side in contact with the metal terminal 30 or on the side in contact with the exterior material 10. When the terminal film 40 is composed of three or more layers, the resin layer 40a may be arranged between the resin layer 40b and the resin layer 40c (see FIG. 5C).

The thickness of the terminal film 40 is preferably 15 μm or more, more preferably 30 to 300 μm, and further preferably 50 to 200 μm from the viewpoint of embedding property and insulating property.

As the electrolyte of the all-solid-state battery, a sulfide-based electrolyte, an oxide-based electrolyte, an organic polymer-based electrolyte, or the like is generally used. When the electrolyte of the all-solid-state battery is a sulfide-based electrolyte, the terminal film 40 preferably contains a hydrogen sulfide adsorbent. When a sulfide-based electrolyte is used, hydrogen sulfide is generated when water is mixed inside the cell, and there is a concern that the adhesion between the metal terminal (tab lead) and the terminal film (tab sealant) may decrease. By adding a hydrogen sulfide adsorbent, the seal strength can be maintained at room temperature and high temperature even when exposed to hydrogen sulfide.

Examples of hydrogen sulfide adsorbents are not particularly limited, but for example, zinc oxide, amorphous metal silicate, hydroxide of zirconium / lanthanoid element, tetravalent metal phosphate potassium permanganate, permanganic acid. Sodium, aluminum oxide, iron hydroxide, silver sulfate, silver acetate, isocyanate compound, aluminum silicate, tetravalent metal phosphate, potassium aluminum sulfate, zeolite, activated carbon, amine compound, ionomer and the like can be used. Since the terminal film 40 contains a hydrogen sulfide adsorbing substance, excellent sealing strength at room temperature and high temperature can be maintained even after exposure to hydrogen sulfide.

The content of the hydrogen sulfide adsorbent in the terminal film 40 is preferably 1 to 50% by mass, more preferably 2 to 25% by mass, still more preferably 5 to 15% by mass, based on the mass of the terminal film 40. Is. When the content of the hydrogen sulfide adsorbing substance of the terminal film 40 is 1% by mass or more, the hydrogen sulfide absorption effect or the adsorption effect is exhibited, while when it is 50% by mass or less, the adhesion and sealant of the terminal film 40 are exhibited. Both aptitude can be achieved. When the terminal film 40 has a multi-layer structure, it is preferable that the layer in contact with the metal terminal 30 does not contain a hydrogen sulfide adsorbent from the viewpoint of adhesion to the metal terminal 30. That is, it is preferable that the layer in contact with the exterior material 10 (for example, the resin layer 40a in FIG. 5B or the resin layers 40a and 40c in FIG. 5C) contains a hydrogen sulfide adsorbent, and the terminal film 40 has three layers. In the case of the above, it is preferable that the intermediate layer (for example, the resin layer 40a in FIG. 5C) contains a hydrogen sulfide adsorbent.

The resin layer 40a contains additives as needed. Examples of the additive include a plasticizer, an antioxidant, a slip agent, a flame retardant, an AB agent, a light stabilizer, a dehydrating agent, and a tackifier.

Although the embodiments of the present disclosure have been described in detail above, the present invention is not limited to the above embodiments, and various modifications and modifications are made within the scope of the gist of the present disclosure described in the claims. Is possible.

For example, in the above embodiment, the embodiment in which the corrosion prevention treatment layer 14 is provided only on one surface (second adhesive layer 17 side) of the barrier layer 13 is illustrated, but the other of the barrier layer 13 is illustrated. The corrosion prevention treatment layer 14 may also be provided on the surface (on the side of the first adhesive layer 12). 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 eliminated. When the base material layer 11 is provided by coating or coating, it is not necessary to provide the first adhesive layer 12. In the above embodiment, the all-solid-state battery is exemplified as the power storage device to which the exterior material 10 is applied, but the exterior material 10 may be applied to another power storage device (for example, a lithium ion battery).

Hereinafter, the present disclosure will be described in more detail based on Examples, but the present disclosure is not limited to the following Examples.

[Material used]
The following materials were prepared in order to prepare the terminal films according to Examples and Comparative Examples.

[Resin material]
・ Polypropylene (block polypropylene): Novatec PP, made by Nippon Polypropylene ・ Polyester 1: A polymer of terephthalic acid as an acid component and ethylene glycol as a glycol component ・ Polyester 2: Terephthalic acid as an acid component and a glycol component Copolymer with ethylene glycol (increased amount of ethylene glycol component compared to polyester 1)
-Polyester 3: Copolymer of naphthalenedicarboxylic acid as an acid component and ethylene glycol as a glycol component-Polyester 4: Telephthalic acid as an acid component, ethylene glycol, butanediol and 1,4- as a glycol component Copolymer with cyclohexanedimethanol ・ Polyester 5: Copolymer of naphthalenedicarboxylic acid as an acid component and ethylene glycol as a glycol component (reduced amount of ethylene glycol component compared to polyester 3)
-Polyamide (Nylon 6 (Ny6)): Gramide, Toyobo-Polycarbonate: Upiron, Mitsubishi Chemical-Polyphenylene ether: Zylon, Asahi Kasei-Modified polyolefin 1 (maleic anhydride): Toyo Tuck (PP), Toyobo-Modified Polyolefin 2 (hydroxyl group): Melsen, Toyobo, modified polyolefin 3 (carboxyl group): Nuclel, Mitsui DuPont Polychemical, modified polyolefin 4 (ester group): EVATANE, Alchema, polyolefin (modified polyolefin) and polyester, etc. Melt blended in advance with a 2-axis compound machine.

[Hydrogen sulfide absorber]
-Zinc oxide: 3 parts by weight was blended with respect to the weight of the terminal film.

[Evaluation method]
(Sample preparation)
As a sample of each example using the above resin material, a terminal film sample cut to 50 mm (TD) × 100 mm (MD) was prepared, and the chemical conversion-treated AL cut to 50 mm × 50 mm was folded in two. One side was heat-sealed with a seal bar having a width of 10 mm at 165 ° C., 0.6 MPa, and 10 sec. Then, the heat-sealed portion was cut to a width of 15 mm. See FIG. 6 for the schematic shape of the sample.

(Initial heat seal strength)
The prepared sample was measured for seal strength at a rate of 50 mm / min in a room temperature environment.
The results were ranked as follows.
A: Burst strength is 25N / 15mm or more B: Burst strength is 20N / 15mm or more and less than 25N / 15mm C: Burst strength is 15N / 15mm or more and less than 20N / 15mm D: Burst strength is less than 15N / 15mm

(Initial heat seal strength after exposure to hydrogen sulfide)
The prepared sample was allowed to stand at room temperature for 72 hours under an environment of hydrogen sulfide concentration of 20 ppm, and the seal strength was measured at a rate of 50 mm / min.
The results were ranked as follows.
A: Burst strength is 25N / 15mm or more B: Burst strength is 20N / 15mm or more and less than 25N / 15mm C: Burst strength is 15N / 15mm or more and less than 20N / 15mm D: Burst strength is less than 15N / 15mm

(High temperature heat seal strength)
The prepared sample was allowed to stand in an environment of 150 ° C. for 5 minutes, and then the seal strength was measured at a speed of 50 mm / min in an environment of 150 ° C.
The results were ranked as follows.
A: Burst strength is 15N / 15mm or more B: Burst strength is 10N / 15mm or more and less than 15N / 15mm C: Burst strength is 5N / 15mm or more and less than 10N / 15mm D: Burst strength is less than 5N / 15mm

(High temperature heat seal strength after exposure to hydrogen sulfide)
The prepared sample was allowed to stand at room temperature for 72 hours in an environment of hydrogen sulfide concentration of 20 ppm, allowed to stand for 5 minutes in an environment of 150 ° C., and then the seal strength was measured at a rate of 50 mm / min in an environment of 150 ° C. bottom.
The results were ranked as follows.
A: Burst strength is 15N / 15mm or more B: Burst strength is 10N / 15mm or more and less than 15N / 15mm C: Burst strength is 5N / 15mm or more and less than 10N / 15mm D: Burst strength is less than 5N / 15mm

Table 1 summarizes the resin composition and evaluation results of Examples 1 to 28 and Comparative Examples 1 to 4 using samples having different resin configurations. In each evaluation, those without a D rank evaluation are considered to have excellent overall quality.

As can be seen from the results shown in Table 1, in each embodiment of the present invention, there are four strengths: initial heat seal strength, initial heat seal strength after hydrogen sulfide exposure, high temperature heat seal strength, and high temperature heat seal strength after hydrogen sulfide exposure. It was confirmed that excellent quality can be obtained under any of the conditions. On the other hand, in each Comparative Example, for example, Comparative Examples 1 and 2 made of only polyolefin resin had poor high-temperature sealing properties, and Comparative Example 3 made of only polyester resin and Comparative Example 4 made of only polyamide resin had initial sealing strength. It was poor and of poor quality.

10 ... Exterior material 11 ... Base material layer 12 ... 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 ... Adhesive layer 30 ... Metal terminal 40 ... Terminal film 40a, 40b, 40c ... Resin layer 50 ... Power storage device main body 100 ... Power storage device

Claims (5)

A terminal film for a power storage device arranged so as to cover a part of the outer peripheral surface of a metal terminal electrically connected to the main body of the power storage device constituting the power storage device, wherein the terminal film serves as a first resin. A terminal film for a power storage device, which comprises a resin composition containing polyolefin and at least one resin selected from polyester, polyamide, polycarbonate, and polyphenylene ether as a second resin. The power storage device according to claim 1, wherein the terminal film contains a modified polyolefin having a modified polar group capable of reacting with polyester, polyamide, polycarbonate, or polyphenylene ether as the second resin. Terminal film for. The terminal film for a power storage device according to claim 1 or 2, wherein the modified polyolefin is modified with maleic anhydride. The polyester or polyamide contained in the terminal film has a crystallinity of 10% or more and less than 70% when cooled at room temperature after heat sealing at 260 ° C. and 0.5 Mpa for 3 seconds. The terminal film for a power storage device according to any one of claims 1 to 3. The terminal film for a power storage device according to any one of claims 1 to 4, wherein the terminal film contains a hydrogen sulfide adsorbing substance.

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