WO2020085189A1

WO2020085189A1 - Aluminum alloy foil, outer package material for electricity storage devices, method for producing same, and electricity storage device

Info

Publication number: WO2020085189A1
Application number: PCT/JP2019/040877
Authority: WO
Inventors: 林　慎二; 大佑安田; 千紘中村
Original assignee: 大日本印刷株式会社
Priority date: 2018-10-24
Filing date: 2019-10-17
Publication date: 2020-04-30
Also published as: JP7205547B2; JP2023052123A; JPWO2020085189A1

Abstract

The present invention provides an aluminum alloy foil for use in an outer package material for electricity storage devices, which is effectively suppressed in corrosion in cases where an electric current is passed therethrough in a state where an electrolyte solution is adhering thereto. An aluminum alloy foil for use in an outer package material for electricity storage devices, which has an Mg content of from 0.20% by mass to 5.50% by mass (inclusive).

Description

Aluminum alloy foil, exterior material for power storage device, manufacturing method thereof, and power storage device

The present disclosure relates to an aluminum alloy foil, an exterior material for an electricity storage device, a method for manufacturing the same, and an electricity storage device.

Conventionally, various types of power storage devices have been developed, but in all power storage devices, packaging materials (exterior materials) have become an indispensable member for encapsulating power storage device elements such as electrodes and electrolytes. Conventionally, metal exterior materials have been often used as exterior materials for power storage devices.

On the other hand, in recent years, as electric vehicles, hybrid electric vehicles, personal computers, cameras, mobile phones, etc. have become higher in performance, power storage devices have been required to have various shapes, and to be thin and lightweight. However, it has been difficult to follow the diversification of the shape with the metal outer casing material for an electricity storage device, which has been widely used in the past, and there is a limitation in weight reduction.

Therefore, in recent years, as a packaging material for power storage devices that can be easily processed into various shapes and can be made thinner and lighter, a film shape in which a base material / aluminum alloy foil layer / heat-fusible resin layer is sequentially laminated. The exterior material has been proposed (for example, see Patent Document 1).

In such a film-like exterior material, generally, a recess is formed by cold molding, and an electric storage device element such as an electrode or an electrolytic solution is arranged in the space formed by the recess, and a heat-fusible resin is used. By heat-sealing the layers to each other, an electricity storage device in which the electricity storage device element is housed inside the exterior material is obtained.

JP, 2008-287971, A

In the process of molding the exterior material for the electricity storage device, the step of accommodating the electricity storage device element in the exterior material for the electricity storage device and heat sealing, and further, the step of bending the heat-sealed portion, the external terminal and the exterior material for the electricity storage device The aluminum alloy foil is short-circuited via a foreign substance, or the pressure unevenness at the time of heat sealing causes the external terminals and the aluminum alloy foil of the exterior material for the electricity storage device to come into close proximity or come into contact with each other to cause a short-circuit, and thermal fusion bonding located in the innermost layer. When fine cracks or pinholes are generated in the heat-resistant resin layer, electricity is passed between the aluminum alloy foil of the exterior material for the electricity storage device and the external terminals through the electrolytic solution that has penetrated into the heat-fusible resin layer. May corrode (especially if the aluminum alloy foil and the negative electrode terminal are short-circuited via the electrolyte, the aluminum alloy foil will corrode. Sui). Corrosion of the aluminum alloy foil causes problems such as expansion of the aluminum alloy foil, which leads to deterioration of the performance of the electricity storage device.

Under such circumstances, the present disclosure aims to provide an aluminum alloy foil for use in an exterior material for an electricity storage device, in which corrosion when electric current is generated in a state where an electrolyte is attached is effectively suppressed. And Another object of the present disclosure is to provide a packaging material for an electricity storage device using the aluminum alloy foil, a method for manufacturing the packaging material for the electricity storage device, and an electricity storage device.

The inventors of the present disclosure have made earnest studies to solve the above problems. As a result, by repeatedly studying the composition of the aluminum alloy foil and setting the content of Mg in a predetermined range, it is possible to effectively suppress the corrosion in the case where energization occurs in the state where the electrolytic solution is attached. I found it.

The present disclosure has been completed by further studies based on these findings. That is, the present disclosure provides the inventions of the following aspects.
An aluminum alloy foil having a Mg content of 0.20% by mass or more and 5.50% by mass or less for use as an exterior material for an electricity storage device.

According to the present disclosure, it is possible to provide an aluminum alloy foil for use as an exterior material for an electricity storage device, in which corrosion is effectively suppressed when electricity is applied in a state where an electrolyte is attached. Further, according to the present disclosure, it is also possible to provide an exterior material for an electricity storage device using the aluminum alloy foil, a method for manufacturing the exterior material for the electricity storage device, and an electricity storage device.

FIG. 3 is a schematic diagram showing an example of a cross-sectional structure of a power storage device exterior material of the present disclosure. FIG. 3 is a schematic diagram showing an example of a cross-sectional structure of a power storage device exterior material of the present disclosure. FIG. 3 is a schematic diagram showing an example of a cross-sectional structure of a power storage device exterior material of the present disclosure. FIG. 3 is a schematic diagram showing an example of a cross-sectional structure of a power storage device exterior material of the present disclosure. 3 is a microscope image of the surface of the folding intersection of the exterior material for an electricity storage device of Example 1, observed after corrosion resistance evaluation. 4 is a microscope image of the surface of the folding intersection of the exterior material for an electricity storage device of Example 2 observed after corrosion resistance evaluation. 3 is a microscope image of the surface of the folding intersection of the exterior material for an electricity storage device of Comparative Example 1, observed after corrosion resistance evaluation. 7 is a microscope image of the surface of the folding intersection of the exterior material for an electricity storage device of Comparative Example 2 observed after corrosion resistance evaluation. It is a schematic diagram for demonstrating the corrosion-resistant evaluation method in an Example. It is a schematic diagram for demonstrating the measuring method of seal strength. It is a schematic diagram for demonstrating the measuring method of seal strength. It is a schematic diagram for demonstrating the measuring method of seal strength. It is a schematic diagram for demonstrating the measuring method of logarithmic decrement rate (DELTA) E by rigid pendulum measurement. It is a schematic diagram for demonstrating the measuring method of seal strength. The temperature difference T ₁ and the temperature difference T ₂ in differential scanning calorimetry is a diagram schematically showing. It is a schematic diagram which shows a crystal grain and a 2nd phase particle in the cross section of the thickness direction of an aluminum alloy foil.

The aluminum alloy foil of the present disclosure is characterized by being an aluminum alloy foil having a Mg content of 0.20% by mass or more and 5.50% by mass or less for use as an exterior material for an electricity storage device. According to the aluminum alloy foil of the present disclosure, the provision of the configuration effectively suppresses corrosion when current is applied in a state where the electrolytic solution is attached. Therefore, the exterior material for an electricity storage device using the aluminum alloy foil of the present disclosure effectively suppresses corrosion of the aluminum alloy foil.

Hereinafter, the aluminum alloy foil, the exterior material for an electricity storage device, the manufacturing method thereof, and the electricity storage device of the present disclosure will be described in detail. In the present specification, the numerical range indicated by “to” means “greater than or equal to” and “less than or equal to”. For example, the expression 2 to 15 mm means 2 mm or more and 15 mm or less.

1. Aluminum alloy foil The aluminum alloy foil of the present disclosure has a Mg content of 0.20% by mass or more and 5.50% by mass or less, and is characterized in that it is used as an exterior material for an electricity storage device. There is no particular limitation on the packaging material for an electricity storage device that can use the aluminum alloy foil of the present disclosure, and the aluminum alloy foil of the present disclosure includes at least a base material layer, a barrier layer, and a heat-fusible resin layer. It can be suitably used as a barrier layer of an exterior material for an electricity storage device. Specific examples of the exterior material for an electricity storage device using the aluminum alloy foil of the present disclosure will be described in detail in the section of “2. Exterior material for electricity storage device”.

The aluminum alloy foil of the present disclosure has a Mg (magnesium) content of 0.20 mass% or more and 5.50 mass% or less. The main component of the aluminum alloy foil of the present disclosure is Al (aluminum), and specifically 93.65 mass% or more is made of aluminum. The Mg content is preferably 0.20% by mass or more and 5.00% by mass or less, more preferably 0.20% by mass or more and 4.00% by mass or less, and further preferably 0.20% by mass or more and 3.00% by mass. % Or less, more preferably 0.20% by mass or more and 2.50% by mass or less, particularly preferably 0.20% by mass or more and 2.20% by mass or less.

The aluminum alloy foil of the present disclosure may contain components other than Mg and Al. Examples of other components include Si (silicon), Fe (iron), Cu (copper), Mn (manganese), Cr (chromium), Zn (zinc), and inevitable impurities. The other component may be one type or two or more types.

The aluminum alloy foil of the present disclosure has a Si content of 0.40% by mass or less and a Fe content, from the viewpoint of an aluminum alloy foil in which corrosion is effectively suppressed when electric current is generated in a state where the electrolytic solution is attached. Content is 0.70 mass% or less, Cu content is 0.20 mass% or less, Mn content is 1.00 mass% or less, Cr content is 0.50 mass% or less, and Zn content is 0.25 mass. % Or less, other unavoidable impurities are individually 0.05% by mass or less and 0.15% by mass or less in total, and the balance is preferably Al. The aluminum alloy foil having such a composition has the same composition as the aluminum alloy having the composition of alloy number A5000 series aluminum of JIS H4000: 2014, and is similar to the known aluminum alloy foil manufacturing method, for example, melting and homogenizing treatment. , Hot rolling, cold rolling, intermediate annealing, cold rolling, and final annealing. Regarding the manufacturing conditions of the aluminum alloy foil, for example, the description in JP 2005-163077 A can be referred to. In addition, the analysis of each chemical component contained in the aluminum alloy foil is performed by the analytical test specified in JIS H4160-1994.

In the present disclosure, as shown in the schematic diagram of FIG. 16, in the cross section in the thickness direction of the aluminum alloy foil, with respect to any 100 second phase particles 3b within the field of view of the optical microscope, the individual second phase particles 3b. When the straight line connecting the leftmost end in the vertical direction with respect to the thickness direction and the rightmost end in the vertical direction with respect to the thickness direction is defined as the diameter y, the diameters of the top 20 second-phase particles 3b are arranged in descending order. The average of the diameters y is preferably 10.0 μm or less. As a result, although the thickness of the aluminum alloy foil is, for example, about 85 μm or less, further about 50 μm or less, further about 40 μm or less, and further about 35 μm or less, the aluminum alloy foil is used for the storage of the electricity storage device. Pinholes and cracks are less likely to occur when laminated on a material and molded, and the outer casing material for an electricity storage device can be provided with excellent moldability. Further, in the present disclosure, since the average of the diameter y of the second phase particles 3b in the aluminum alloy foil is 10.0 μm or less, the thickness of the aluminum alloy foil is, for example, about 85 μm or less, further about 50 μm or less, and further Even if it is about 40 μm or less, or about 35 μm or less, and the total thickness of the exterior material for an electricity storage device is as thin as the thickness described later, for example, pinholes and cracks are less likely to occur during molding, and excellent moldability is obtained. Is equipped with.

Further, from the viewpoint of further improving the moldability, the average of the diameter y is more preferably about 1.0 to 8.0 μm, and further preferably about 1.0 to 6.0 μm. Since FIG. 16 is a schematic diagram, drawing is omitted and 100 second phase particles 3b are not drawn.

In the present disclosure, the second phase particles contained in the aluminum alloy foil refer to the intermetallic compound particles present in the aluminum alloy, and the precipitation that precipitates during the crystallization phase separated by rolling or the homogenization treatment or annealing. It is a phase particle.

When the cross section of the aluminum alloy foil in the thickness direction is observed with a scanning electron microscope (SEM), the crystal grains usually draw a boundary line in contact with a plurality of crystals. On the other hand, the second phase particles usually have a single boundary line. Further, the crystal grains and the second phase grains have different phases on the SEM image because they have different phases. Furthermore, when the cross section in the thickness direction of the aluminum alloy foil is observed with an optical microscope, only the second phase particles appear black due to the phase difference between the crystal grains and the second phase particles, which makes the observation easy. become.

The average crystal grain size of the aluminum alloy foil is preferably 20.0 μm or less, more preferably about 1.0 to 15.0 μm, further preferably about 1.0 to 10.0 μm, from the viewpoint of further improving the formability. Is mentioned. When the average crystal grain size in the aluminum alloy foil is 20.0 μm or less and the diameter y of the second phase particles 3b is the above value, the moldability of the exterior material for an electricity storage device described later is further enhanced. Can be increased.

In the present disclosure, the average crystal grain size in the aluminum alloy foil is obtained by observing a cross section in the thickness direction of the aluminum alloy foil with a scanning electron microscope (SEM), and regarding 100 crystal grains 3a of the aluminum alloy located in the visual field, As shown in the schematic view of FIG. 16, when the straight line connecting the leftmost end in the direction perpendicular to the thickness direction of each crystal grain and the rightmost end in the direction perpendicular to the thickness direction is defined as the maximum diameter x, 100 It means the average value of the maximum diameter x of each crystal grain. Since FIG. 16 is a schematic diagram, the drawing is omitted and 100 crystal grains 3a are not drawn.

The thickness of the aluminum alloy foil may be at least a function as a barrier layer that suppresses the entry of moisture in the exterior material for an electricity storage device, and the lower limit is about 9 μm or more and the upper limit is about 200 μm or less. From the viewpoint of reducing the thickness of the exterior material for an electricity storage device, the thickness of the aluminum alloy foil is, for example, preferably about 85 μm or less, more preferably about 50 μm or less, still more preferably about 40 μm or less, and particularly preferably about the upper limit. 35 μm or less, and the lower limit is preferably about 10 μm or more, further preferably about 20 μm or more, more preferably about 25 μm or more, and the preferable range of the thickness is about 10 to 85 μm, about 10 to 50 μm. 10 to 40 μm, 10 to 35 μm, 20 to 85 μm, 20 to 50 μm, 20 to 40 μm, 20 to 35 μm, 25 to 85 μm, 25 to 50 μm, 25 to 40 μm, 25 to 35 μm Is mentioned.

Also, it is preferable that at least one surface of the aluminum alloy foil is provided with a corrosion resistant film in order to prevent the aluminum alloy foil from being melted or corroded. The aluminum alloy foil may have a corrosion resistant coating on both sides. Here, the corrosion-resistant coating is, for example, hydrothermal conversion treatment such as boehmite treatment, chemical conversion treatment, anodizing treatment, plating treatment such as nickel or chromium, and corrosion prevention treatment for coating a coating agent of aluminum alloy foil. It refers to a thin film that is applied to the surface to make the aluminum alloy foil have corrosion resistance (for example, acid resistance, alkali resistance, etc.). Specifically, the corrosion resistant film means a film that improves the acid resistance of the aluminum alloy foil (acid resistant film), a film that improves the alkali resistance of the aluminum alloy foil (alkali resistant film), and the like. As the treatment for forming the corrosion resistant film, one type may be performed, or two or more types may be combined and performed. Further, not only one layer but also multiple layers can be formed. Further, among these treatments, the hydrothermal conversion treatment and the anodizing treatment are treatments for dissolving the surface of the metal foil with a treatment agent to form a metal compound having excellent corrosion resistance. Note that these processes may be included in the definition of the chemical conversion process. When the aluminum alloy foil has a corrosion resistant film, the aluminum alloy foil including the corrosion resistant film is used.

The corrosion-resistant film prevents delamination between the aluminum alloy foil and the base material layer during the molding of the exterior material for an electricity storage device, and hydrogen fluoride generated by the reaction between the electrolyte and moisture causes the aluminum alloy foil surface to Dissolves, corrodes, prevents aluminum oxide existing on the surface of the aluminum alloy foil from melting and corroding, and improves the adhesiveness (wettability) of the aluminum alloy foil surface, and the base material layer and the aluminum alloy during heat sealing. The effects of preventing delamination with the foil and preventing delamination between the base material layer and the aluminum alloy foil during molding are shown.

Various types of corrosion-resistant films formed by chemical conversion treatment are known, and are mainly at least one of phosphates, chromates, fluorides, triazine thiol compounds, and rare earth oxides. And a corrosion resistant film containing the like. Examples of the chemical conversion treatment using a phosphate or chromate include chromate chromate treatment, chromate phosphoric acid treatment, phosphoric acid-chromate treatment, chromate treatment, and the like. Examples of the compound include chromium nitrate, chromium fluoride, chromium sulfate, chromium acetate, chromium oxalate, chromium diphosphate, acetyl acetate chromate, chromium chloride, potassium chromium sulfate and the like. Further, examples of the phosphorus compound used for these treatments include sodium phosphate, potassium phosphate, ammonium phosphate, polyphosphoric acid, and the like. Further, examples of the chromate treatment include etching chromate treatment, electrolytic chromate treatment, coating type chromate treatment and the like, and coating type chromate treatment is preferable. In this coating type chromate treatment, at least the inner layer side of the barrier layer (eg, aluminum alloy foil) is first subjected to a well-known method such as an alkali dipping method, an electrolytic cleaning method, an acid cleaning method, an electrolytic acid cleaning method, and an acid activation method. A degreasing treatment is performed by a treatment method, and thereafter, a phosphate metal such as Cr (chromium) phosphate, Ti (titanium) phosphate, Zr (zirconium) phosphate, Zn (zinc) phosphate, etc. A treatment liquid containing a salt and a mixture of these metal salts as a main component, or a treatment liquid containing a non-metallic phosphate and a mixture of these non-metal salts as a main component, or a mixture of these with a synthetic resin or the like. This is a treatment in which a treatment liquid composed of a mixture is applied by a well-known coating method such as a roll coating method, a gravure printing method and a dipping method, and then dried. As the treatment liquid, various solvents such as water, alcohol solvents, hydrocarbon solvents, ketone solvents, ester solvents, ether solvents can be used, and water is preferable. Examples of the resin component used at this time include polymers such as phenol resins and acrylic resins, and aminated phenol polymers having repeating units represented by the following general formulas (1) to (4) are used. Examples include the chromate treatment used. In the aminated phenol polymer, the repeating units represented by the following general formulas (1) to (4) may be contained alone or in any combination of two or more. Good. Acrylic resin must be polyacrylic acid, acrylic acid methacrylic acid ester copolymer, acrylic acid maleic acid copolymer, acrylic acid styrene copolymer, or their derivatives such as sodium salt, ammonium salt, amine salt, etc. Is preferred. Particularly preferred are polyacrylic acid derivatives such as ammonium salt, sodium salt, or amine salt of polyacrylic acid. In the present disclosure, polyacrylic acid means a polymer of acrylic acid. Further, the acrylic resin is also preferably a copolymer of acrylic acid and a dicarboxylic acid or a dicarboxylic acid anhydride, an ammonium salt of a copolymer of acrylic acid and a dicarboxylic acid or a dicarboxylic acid anhydride, a sodium salt, Alternatively, it is also preferably an amine salt. Only one type of acrylic resin may be used, or two or more types may be mixed and used.

In formulas (1) to (4), X represents a hydrogen atom, a hydroxy group, an alkyl group, a hydroxyalkyl group, an allyl group or a benzyl group. R ¹ and R ² are the same or different and each represents a hydroxy group, an alkyl group, or a hydroxyalkyl group. In the general formulas (1) to (4), examples of the alkyl group represented by X, R ¹ and R ² include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, Examples thereof include linear or branched alkyl groups having 1 to 4 carbon atoms such as tert-butyl group. Examples of the hydroxyalkyl group represented by X, R ¹ and R ² include, for example, hydroxymethyl group, 1-hydroxyethyl group, 2-hydroxyethyl group, 1-hydroxypropyl group, 2-hydroxypropyl group and 3-hydroxypropyl group. Linear or branched chain having 1 to 4 carbon atoms, which is substituted with one hydroxy group such as hydroxypropyl group, 1-hydroxybutyl group, 2-hydroxybutyl group, 3-hydroxybutyl group, 4-hydroxybutyl group An alkyl group is mentioned. In the general formulas (1) to (4), the alkyl group and the hydroxyalkyl group represented by X, R ¹ and R ² may be the same or different. In the general formulas (1) to (4), X is preferably a hydrogen atom, a hydroxy group or a hydroxyalkyl group. The number average molecular weight of the aminated phenol polymer having the repeating units represented by the general formulas (1) to (4) is, for example, preferably about 500 to 1,000,000, and more preferably about 1,000 to 20,000. More preferable. The aminated phenol polymer is produced by, for example, polycondensing a phenol compound or a naphthol compound with formaldehyde to produce a polymer having a repeating unit represented by the above general formula (I) or general formula (III), and then forming formaldehyde. And an amine (R ¹ R ² NH) to introduce a functional group (—CH ₂ NR ¹ R ² ) into the polymer obtained above. The aminated phenol polymer is used alone or in combination of two or more.

Another example of the corrosion resistant film is formed by a coating type corrosion prevention treatment in which a coating agent containing at least one selected from the group consisting of rare earth element oxide sols, anionic polymers and cationic polymers is applied. A thin film is used. The coating agent may further contain phosphoric acid or phosphate, and a cross-linking agent that cross-links the polymer. In the rare earth element oxide sol, fine particles of rare earth element oxide (for example, particles having an average particle diameter of 100 nm or less) are dispersed in a liquid dispersion medium. Examples of the rare earth element oxide include cerium oxide, yttrium oxide, neodymium oxide, and lanthanum oxide, and cerium oxide is preferable from the viewpoint of further improving the adhesiveness. The rare earth element oxides contained in the corrosion resistant coating may be used alone or in combination of two or more. As the liquid dispersion medium of the rare earth element oxide sol, various solvents such as water, alcohol solvents, hydrocarbon solvents, ketone solvents, ester solvents, ether solvents can be used, and water is preferable. Examples of the cationic polymer include polyethyleneimine, an ionic polymer complex composed of a polymer having polyethyleneimine and a carboxylic acid, a primary amine-grafted acrylic resin obtained by graft-polymerizing a primary amine on an acrylic main skeleton, polyallylamine or a derivative thereof. , Aminated phenol and the like are preferable. The anionic polymer is preferably poly (meth) acrylic acid or a salt thereof, or a copolymer containing (meth) acrylic acid or a salt thereof as a main component. Further, it is preferable that the cross-linking agent is at least one selected from the group consisting of a compound having any one of an isocyanate group, a glycidyl group, a carboxyl group and an oxazoline group, and a silane coupling agent. The phosphoric acid or phosphate is preferably condensed phosphoric acid or condensed phosphate.

As an example of the corrosion-resistant coating, a dispersion of fine particles of metal oxide such as aluminum oxide, titanium oxide, cerium oxide, and tin oxide or barium sulfate in phosphoric acid is applied to the surface of the barrier layer, Examples include those formed by performing a baking treatment at a temperature of not less than ° C.

The corrosion-resistant film may have a laminated structure in which at least one of a cationic polymer and an anionic polymer is further laminated, if necessary. Examples of the cationic polymer and the anionic polymer include those mentioned above.

Note that analysis of the composition of the corrosion resistant film can be performed using, for example, time-of-flight secondary ion mass spectrometry.

The amount of the corrosion resistant film formed on the surface of the aluminum alloy foil in the chemical conversion treatment is not particularly limited, but, for example, when the coating type chromate treatment is performed, a chromic acid compound per 1 m ² of the surface of the aluminum alloy foil is used. Is about 0.5 to 50 mg, preferably about 1.0 to 40 mg in terms of chromium, and the phosphorus compound is, for example, about 0.5 to 50 mg, preferably about 1.0 to 40 mg in terms of phosphorus, and aminated phenol polymer. Is preferably contained in a ratio of, for example, about 1.0 to 200 mg, preferably about 5.0 to 150 mg.

The thickness of the corrosion-resistant film is not particularly limited, but from the viewpoint of the cohesive force of the film and the adhesion with the barrier layer or the heat-fusible resin layer, it is preferably about 1 nm to 20 μm, more preferably 1 nm to 100 nm. Degree, and more preferably about 1 nm to 50 nm. The thickness of the corrosion-resistant coating can be measured by observation with a transmission electron microscope or a combination of observation with a transmission electron microscope and energy dispersive X-ray spectroscopy or electron beam energy loss spectroscopy. By analysis of the composition of the corrosion-resistant coating using time-of-flight secondary ion mass spectrometry, for example, at least one secondary ion consisting of Ce, P, and O (eg, Ce ₂ PO ₄ ⁺ , CePO ₄ ^−, etc. Species) or, for example, a peak derived from a secondary ion of Cr, P, and O (for example, at least one of CrPO ₂ ⁺ , CrPO ₄ ⁻ ).

The chemical conversion treatment is carried out by applying a solution containing a compound used for forming a corrosion resistant film to the surface of the aluminum alloy foil by a bar coating method, a roll coating method, a gravure coating method, a dipping method, etc. It is carried out by heating so that the temperature becomes about 70 to 200 ° C. Further, before the aluminum alloy foil is subjected to the chemical conversion treatment, the aluminum alloy foil may be previously subjected to a degreasing treatment by an alkali dipping method, an electrolytic cleaning method, an acid cleaning method, an electrolytic acid cleaning method, or the like. By performing the degreasing treatment in this manner, it becomes possible to more efficiently perform the chemical conversion treatment on the surface of the aluminum alloy foil. In addition, by using an acid degreasing agent in which a fluorine-containing compound is dissolved in an inorganic acid for degreasing treatment, it is possible to form not only the degreasing effect of the metal foil but also a passive metal fluoride. In such cases, only degreasing treatment may be performed.

2. Power Storage Device Exterior Material The power storage device exterior material 10 of the present disclosure includes at least a base material layer 1, a barrier layer 3, and a heat-fusible resin layer 4 in this order as shown in FIGS. 1 to 4. It is composed of a laminate. In the exterior material 10 for an electricity storage device, the base material layer 1 is the outermost layer side, and the heat-fusible resin layer 4 is the innermost layer. When assembling an electricity storage device using the electricity storage device exterior material 10 and the electricity storage device element, the peripheral edges are heat-sealed with the heat-fusible resin layers 4 of the electricity storage device exterior material 10 facing each other. The electricity storage device element is housed in the space formed by.

The barrier layer 3 of the exterior material for an electricity storage device of the present disclosure includes the aluminum alloy foil of the present disclosure. That is, the barrier layer 3 of the exterior material for an electricity storage device of the present disclosure can be configured by the aluminum alloy foil of the present disclosure. In the exterior material for an electricity storage device of the present disclosure using the aluminum alloy foil of the present disclosure, corrosion of the aluminum alloy foil is effectively suppressed.

For example, as shown in FIGS. 2 to 4, the exterior material 10 for an electricity storage device is provided between the base material layer 1 and the barrier layer 3 for the purpose of enhancing the adhesiveness between these layers and the like, if necessary. The adhesive layer 2 may be included. Further, as shown in, for example, FIGS. 3 and 4, an adhesive layer 5 is provided between the barrier layer 3 and the heat-fusible resin layer 4 for the purpose of enhancing the adhesiveness between these layers, if necessary. May have. Further, as shown in FIG. 4, a surface coating layer 6 and the like may be provided on the outside of the base material layer 1 (on the side opposite to the heat-fusible resin layer 4 side), if necessary.

The thickness of the laminate constituting the exterior material 10 for an electricity storage device is not particularly limited, but the upper limit is, for example, 300 μm or less, preferably about 180 μm or less, about 155 μm or less from the viewpoint of cost reduction, energy density improvement, and the like. , About 120 μm or less, and the lower limit is preferably about 35 μm or more, about 45 μm or more, about 60 μm or more, from the viewpoint of maintaining the function of the power storage device exterior material of protecting the power storage device element. Preferred ranges are, for example, about 35 to 180 μm, about 35 to 155 μm, about 35 to 120 μm, about 45 to 180 μm, about 45 to 155 μm, about 45 to 120 μm, about 60 to 180 μm, about 60 to 155 μm, about 60 to 120 μm. The degree can be mentioned.

Note that in the exterior material for an electricity storage device, with respect to the barrier layer 3 described later, it is usually possible to distinguish between MD (Machine Direction) and TD (Transverse Direction) in the manufacturing process. For example, when the barrier layer 3 is composed of an aluminum alloy foil, linear streaks called so-called rolling marks are formed on the surface of the aluminum alloy foil in the rolling direction (RD: Rolling Direction) of the aluminum alloy foil. ing. Since the rolling mark extends along the rolling direction, the rolling direction of the aluminum alloy foil can be grasped by observing the surface of the aluminum alloy foil. In addition, in the manufacturing process of the laminated body, since the MD of the laminated body and the RD of the aluminum alloy foil usually match, the surface of the aluminum alloy foil of the laminated body is observed, and the rolling direction (RD) of the aluminum alloy foil is observed. By specifying, the MD of the laminate can be specified. Since the TD of the laminated body is in the direction perpendicular to the MD of the laminated body, the TD of the laminated body can be specified.

In the electricity storage device exterior material 10 of the present disclosure, in a state where the heat-fusible resin layers 4 are opposed to each other, a metal plate having a width of 7 mm is used, and a temperature of 190 ° C. is applied from both sides of the test sample in the laminating direction. The heat-fusible resin layers 4 are heat-fused by heating and pressurizing under a pressure of 2.0 MPa for a time of 3 seconds (see FIGS. 10 and 11), and then, as shown in FIG. In the environment of temperature 25 ° C., tensile speed of 300 mm / min, peeling angle of 180 °, and chuck distance of 50 mm for 1.5 seconds from the start of tensile strength measurement. In the meantime, the maximum value of the tensile strength (seal strength) measured by peeling the heat-sealed interface is preferably 110 N / 15 mm or more, and more preferably 120 N / 15 mm or more. The upper limit of the tensile strength is, for example, about 200 N / 15 mm or less, and preferable ranges include 110 to 200 N / 15 mm and 120 to 200 N / 15 mm. In order to set such a tensile strength, for example, the type, composition, molecular weight, etc. of the resin forming the heat-fusible resin layer are adjusted.

Furthermore, in the exterior material 10 for an electricity storage device of the present disclosure, a metal plate having a width of 7 mm is used in a state where the heat-fusible resin layers 4 are opposed to each other, and the temperature is 190 ° C. from both sides of the test sample in the stacking direction. , The surface pressure is 2.0 MPa and the time is 3 seconds for heating and pressurization to heat-bond the heat-fusible resin layers 4 together (see FIGS. 10 and 11), and then as shown in FIG. , T-peeling, using a tensile tester, under conditions of a temperature of 140 ° C., a pulling speed of 300 mm / min, a peeling angle of 180 °, and a chuck distance of 50 mm. The maximum value of the tensile strength (seal strength) measured by peeling the heat-sealed interface for a period of time is preferably 3.0 N / 15 mm or more, and preferably 4.0 N / 15 mm or more. More preferable. The upper limit of the tensile strength is, for example, about 5.0 N / 15 mm or less, and preferable ranges include 3.0 to 5.0 N / 15 mm and 4.0 to 5.0 N / 15 mm. As described above, since the heat resistant temperature of the separator inside the electricity storage device is generally set to around 120 to 140 ° C., the tensile strength (seal) in the high temperature environment of 140 ° C. in the electricity storage device exterior material of the present disclosure. The maximum value of (strength) preferably satisfies the above value. In order to set such a tensile strength, for example, the type, composition, molecular weight, etc. of the resin forming the heat-fusible resin layer are adjusted.

As shown in Examples described later, the tensile test at each temperature is performed in a constant temperature bath, and the test sample is attached to the chuck for 2 minutes in the constant temperature bath at a predetermined temperature (25 ° C or 140 ° C). Hold and then start the measurement.

Sealing strength after contact with electrolytic solution In addition, the exterior material 10 for an electricity storage device of the present disclosure has an electrolytic solution (the concentration of lithium hexafluorophosphate is 1 mol / l, and ethylene carbonate and diethyl carbonate are contained in an environment of 85 ° C). A solution of dimethyl carbonate in a volume ratio of 1: 1: 1 (a solution obtained by mixing ethylene carbonate, diethyl carbonate, and dimethyl carbonate in a volume ratio of 1: 1: 1) was used as an outer packaging material for an electricity storage device. After being contacted for a time, the heat-fusible resin layers are heat-melted under the conditions of a temperature of 190 ° C., a surface pressure of 2.0 MPa, and a time of 3 seconds while the electrolytic solution is attached to the surface of the heat-fusible resin layer. The sealing strength when adhered and peeling off the heat-fused interface is 60% or more (the sealing strength retention rate is 60% or more) of the sealing strength when not contacted with the electrolytic solution. Preferably Rukoto, more preferably 80% or more, more preferably 100%.

(Method of measuring seal strength retention rate)
Using the seal strength before contact with the electrolytic solution measured by the following method (100%), the retention rate (%) of the seal strength after contact with the electrolytic solution is calculated.

<Measurement of seal strength before contact with electrolyte>
In <Measurement of seal strength after contact with electrolytic solution> described below, tensile strength (seal strength) is measured in the same manner except that the electrolytic solution is not injected into the test sample. The maximum tensile strength until the heat-sealed portion is completely peeled off is defined as the sealing strength before contact with the electrolytic solution.

<Measurement of seal strength after contact with electrolyte>
As shown in the schematic view of FIG. 14, the exterior material for an electricity storage device is cut into a rectangle having a width (x direction) of 100 mm × length (z direction) of 200 mm to obtain a test sample (FIG. 14 a). The test sample is folded back at the center in the z direction so that the heat-fusible resin layer sides overlap (FIG. 14b). Next, both ends in the x direction of the folded back test sample were sealed by heat sealing (temperature 190 ° C., surface pressure 2.0 MPa, time 3 seconds), and formed into a bag shape having one opening E (FIG. 14c). Next, an electrolyte solution (concentration of lithium hexafluorophosphate is 1 mol / l and volume ratio of ethylene carbonate, diethyl carbonate and dimethyl carbonate is 1: 1: 1 from the opening E of the test sample formed in the shape of a bag. 6 g of the solution of 1) is injected (FIG. 14d), and the end of the opening E is sealed by heat sealing (temperature 190 ° C., surface pressure 2.0 MPa, time 3 seconds) (FIG. 14e). Next, with the folded back portion of the bag-shaped test sample facing downward, the bag is left to stand in an environment of a temperature of 85 ° C. for a predetermined storage time (a time for contacting with an electrolytic solution, 72 hours or the like). The end of the test sample is then cut (Fig. 14e) and the electrolyte is drained. Next, with the electrolytic solution attached to the surface of the heat-fusible resin layer, the upper and lower surfaces of the test sample were sandwiched by metal plates (7 mm width), and the temperature was 190 ° C., the surface pressure was 1.0 MPa, and the conditions were 3 seconds. The heat-fusible resin layers are heat-sealed together (FIG. 14f). Next, the test sample is cut into a width of 15 mm with a double-edged sample cutter so that the seal strength at a width (x direction) of 15 mm can be measured (FIGS. 14f and 14g). Next, using a tensile tester, a T-peel is peeled off at the temperature of 25 ° C. under an environment of a pulling speed of 300 mm / min, a peeling angle of 180 ° and a chuck distance of 50 mm. Then, the tensile strength (seal strength) is measured (FIG. 12). The maximum tensile strength until the heat-sealed portion is completely peeled off is defined as the sealing strength after contact with the electrolytic solution.

Each layer forming the exterior material for a power storage device [base material layer 1]
In the present disclosure, the base material layer 1 is a layer provided for the purpose of exerting a function as a base material of the exterior material for an electricity storage device. The base material layer 1 is located on the outer layer side of the exterior material for an electricity storage device.

The material forming the base material layer 1 is not particularly limited as long as it has a function as a base material, that is, at least an insulating property. The base material layer 1 can be formed by using, for example, a resin, and the resin may contain an additive described below.

When the base material layer 1 is made of resin, the base material layer 1 may be, for example, a resin film made of resin, or may be formed by applying resin. The resin film may be an unstretched film or a stretched film. Examples of the stretched film include a uniaxially stretched film and a biaxially stretched film, and a biaxially stretched film is preferable. Examples of the stretching method for forming the biaxially stretched film include a sequential biaxial stretching method, an inflation method and a simultaneous biaxial stretching method. Examples of the method for applying the resin include a roll coating method, a gravure coating method and an extrusion coating method.

Examples of the resin forming the base material layer 1 include resins such as polyester, polyamide, polyolefin, epoxy resin, acrylic resin, fluororesin, polyurethane, silicon resin, and phenol resin, and modified products of these resins. The resin forming the base material layer 1 may be a copolymer of these resins or a modified product of the copolymer. Further, it may be a mixture of these resins.

Among these, the resin forming the base material layer 1 is preferably polyester or polyamide.

Specific examples of the polyester include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolyester. Further, examples of the copolyester include a copolyester having ethylene terephthalate as a main repeating unit. Specifically, a copolymer polyester which is mainly composed of ethylene terephthalate as a repeating unit and is polymerized with ethylene isophthalate (hereinafter abbreviated to polyethylene (terephthalate / isophthalate)), polyethylene (terephthalate / adipate), polyethylene (terephthalate / Sodium sulfoisophthalate), polyethylene (terephthalate / sodium isophthalate), polyethylene (terephthalate / phenyl-dicarboxylate), polyethylene (terephthalate / decanedicarboxylate) and the like. These polyesters may be used alone or in combination of two or more.

Specific examples of polyamides include aliphatic polyamides such as nylon 6, nylon 66, nylon 610, nylon 12, nylon 46, and copolymers of nylon 6 and nylon 66; terephthalic acid and / or isophthalic acid. Hexamethylenediamine-isophthalic acid-terephthalic acid copolyamides such as nylon 6I, nylon 6T, nylon 6IT, nylon 6I6T (I represents isophthalic acid, T represents terephthalic acid) containing the derived constitutional unit, polyamide MXD6 (polymeta Polyamides containing aromatics such as silylene adipamide; alicyclic polyamides such as polyamide PACM6 (polybis (4-aminocyclohexyl) methane adipamide); further lactam components and isocyanate components such as 4,4′-diphenylmethane-diisocyanate Polyamides obtained by copolymerizing, copolymerized polyamide and polyester or polyalkylene polyester amide copolymer is a copolymer of a polyether glycol and a polyether ester amide copolymers, polyamides such as a copolymer thereof. These polyamides may be used alone or in combination of two or more.

The base material layer 1 preferably contains at least one of a polyester film, a polyamide film, and a polyolefin film, and preferably contains at least one of a stretched polyester film, a stretched polyamide film, and a stretched polyolefin film, It is more preferable to include at least one of a stretched polyethylene terephthalate film, a stretched polybutylene terephthalate film, a stretched nylon film, and a stretched polypropylene film. A biaxially stretched polyethylene terephthalate film, a biaxially stretched polybutylene terephthalate film, a biaxially stretched nylon film. More preferably, at least one of the biaxially oriented polypropylene films is included.

The base material layer 1 may be a single layer or may be composed of two or more layers. When the base material layer 1 is composed of two or more layers, the base material layer 1 may be a laminate in which resin films are laminated with an adhesive or the like, or a resin is coextruded into two or more layers. It may be a laminate of the above resin films. Further, a resin film laminate obtained by coextruding a resin into two or more layers may be the unstretched base material layer 1 or may be uniaxially or biaxially stretched to form the base material layer 1.

Specific examples of a laminate of two or more resin films in the base material layer 1 include a laminate of a polyester film and a nylon film, a laminate of two or more nylon films, a laminate of two or more polyester films. And the like, and preferably a laminate of a stretched nylon film and a stretched polyester film, a laminate of two or more stretched nylon films, and a laminate of two or more stretched polyester films. For example, when the base material layer 1 is a laminate of two resin films, a laminate of a polyester resin film and a polyester resin film, a laminate of a polyamide resin film and a polyamide resin film, or a polyester resin film and a polyamide resin film. A laminated body is preferable, and a laminated body of a polyethylene terephthalate film and a polyethylene terephthalate film, a laminated body of a nylon film and a nylon film, or a laminated body of a polyethylene terephthalate film and a nylon film is more preferable. In addition, since the polyester resin does not easily discolor when an electrolytic solution adheres to the surface, when the base material layer 1 is a laminate of two or more resin films, the polyester resin film is It is preferably located in the outermost layer.

When the base material layer 1 is a laminate of two or more resin films, the two or more resin films may be laminated via an adhesive. Examples of preferable adhesives include the same adhesives as those exemplified for the adhesive layer 2 described later. The method for laminating the two or more resin films is not particularly limited, and known methods can be adopted, and examples thereof include a dry laminating method, a sandwich laminating method, an extrusion laminating method, and a thermal laminating method, and preferably a dry laminating method. A laminating method can be mentioned. When laminating by a dry laminating method, it is preferable to use a polyurethane adhesive as the adhesive. At this time, the thickness of the adhesive is, for example, about 2 to 5 μm. Also, an anchor coat layer may be formed on the resin film and laminated. The anchor coat layer may be the same as the adhesive exemplified in the adhesive layer 2 described later. At this time, the thickness of the anchor coat layer is, for example, about 0.01 to 1.0 μm.

Further, even if additives such as a lubricant, a flame retardant, an antiblocking agent, an antioxidant, a light stabilizer, a tackifier, and an antistatic agent are present on at least one of the surface and the inside of the base material layer 1. Good. As the additive, only one kind may be used, or two or more kinds may be mixed and used.

In the present disclosure, a lubricant is preferably present on the surface of the base material layer 1 from the viewpoint of enhancing the moldability of the exterior material for an electricity storage device. The lubricant is not particularly limited, but preferably an amide lubricant is used. Specific examples of the amide-based lubricant include saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, methylol amides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, fatty acid ester amides, aromatic bisamides, and the like. Specific examples of the saturated fatty acid amide include lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, and hydroxystearic acid amide. Specific examples of unsaturated fatty acid amides include oleic acid amide and erucic acid amide. Specific examples of the substituted amide include N-oleylpalmitic acid amide, N-stearyl stearic acid amide, N-stearyl oleic acid amide, N-oleyl stearic acid amide, and N-stearyl erucic acid amide. Specific examples of the methylolamide include methylolstearic acid amide. Specific examples of the saturated fatty acid bisamide include methylenebisstearic acid amide, ethylenebiscapric acid amide, ethylenebislauric acid amide, ethylenebisstearic acid amide, ethylenebishydroxystearic acid amide, ethylenebisbehenic acid amide, and hexamethylenebisstearic acid amide. Examples thereof include acid amide, hexamethylene bisbehenic acid amide, hexamethylene hydroxystearic acid amide, N, N′-distearyl adipic acid amide and N, N′-distearyl sebacic acid amide. Specific examples of the unsaturated fatty acid bisamide include ethylene bisoleic acid amide, ethylene bis erucic acid amide, hexamethylene bis oleic acid amide, N, N'-dioleyl adipate amide, N, N'-dioleyl sebacic acid amide. And so on. Specific examples of the fatty acid ester amide include stearoamide ethyl stearate. Further, specific examples of the aromatic bisamide include m-xylylenebisstearic acid amide, m-xylylenebishydroxystearic acid amide, N, N'-distearylisophthalic acid amide and the like. The lubricant may be used alone or in combination of two or more.

When the lubricant is present on the surface of the base material layer 1, its amount is not particularly limited, but is preferably about 3 mg / m ² or more, more preferably about 4 to 15 mg / m ² , and further preferably 5 to 14 mg. / M ² is included.

The lubricant present on the surface of the base material layer 1 may be one in which the lubricant contained in the resin forming the base material layer 1 is exuded, or the one coated with the lubricant on the surface of the base material layer 1. May be.

The thickness of the base material layer 1 is not particularly limited as long as it can function as a base material, but is, for example, about 3 to 50 μm, preferably about 10 to 35 μm. When the base material layer 1 is a laminate of two or more resin films, the thickness of the resin film forming each layer is preferably about 2 to 25 μm.

[Adhesive layer 2]
In the exterior material for an electricity storage device of the present disclosure, the adhesive layer 2 is a layer provided between the base material layer 1 and the barrier layer 3 as needed for the purpose of enhancing the adhesiveness.

The adhesive layer 2 is formed of an adhesive that can bond the base material layer 1 and the barrier layer 3 together. The adhesive used for forming the adhesive layer 2 is not limited, and may be any of a chemical reaction type, a solvent volatilization type, a heat melting type, a heat pressure type and the like. Further, it may be a two-component curing type adhesive (two-component adhesive), a one-component curing type adhesive (one-component adhesive), or a resin that does not undergo a curing reaction. The adhesive layer 2 may be a single layer or a multilayer.

Specific examples of the adhesive component contained in the adhesive include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, polyesters such as copolyester; polyether; polyurethane; epoxy resin; Phenol resin; nylon 6, nylon 66, nylon 12, polyamide such as copolyamide; polyolefin resin such as polyolefin, cyclic polyolefin, acid modified polyolefin, acid modified cyclic polyolefin; polyvinyl acetate; cellulose; (meth) acrylic resin; Polyimide; Polycarbonate; Amino resin such as urea resin and melamine resin; Rubber such as chloroprene rubber, nitrile rubber and styrene-butadiene rubber; Silicone resin, etc. It is. These adhesive components may be used alone or in combination of two or more. Among these adhesive components, a polyurethane adhesive is preferable. Further, the resin serving as the adhesive component may be used in combination with an appropriate curing agent to enhance the adhesive strength. The curing agent is selected from polyisocyanates, polyfunctional epoxy resins, oxazoline group-containing polymers, polyamine resins, acid anhydrides, etc. depending on the functional groups of the adhesive component.

Examples of the polyurethane adhesive include a polyurethane adhesive containing a base compound containing a polyol compound and a curing agent containing an isocyanate compound. Preferred is a two-component curing type polyurethane adhesive containing a polyol such as a polyester polyol, a polyether polyol and an acrylic polyol as a main component and an aromatic or aliphatic polyisocyanate as a curing agent. Further, as the polyol compound, it is preferable to use a polyester polyol having a hydroxyl group at the side chain in addition to the hydroxyl group at the terminal of the repeating unit. Since the adhesive layer 2 is made of a polyurethane adhesive, excellent resistance to the electrolytic solution is imparted to the exterior material for an electricity storage device, and the base layer 1 is prevented from peeling off even when the electrolytic solution adheres to the side surface. .

Further, the adhesive layer 2 may contain other components as long as it does not impair the adhesiveness, and may contain a colorant, a thermoplastic elastomer, a tackifier, a filler, or the like. Since the adhesive layer 2 contains the coloring agent, the exterior material for the electricity storage device can be colored. Known colorants such as pigments and dyes can be used as the colorant. Moreover, only one type of colorant may be used, or two or more types may be mixed and used.

The type of pigment is not particularly limited as long as it does not impair the adhesiveness of the adhesive layer 2. Examples of the organic pigment include azo-based, phthalocyanine-based, quinacridone-based, anthraquinone-based, dioxazine-based, indigothioindigo-based, perinone-perylene-based, isoindolenin-based, benzimidazolone-based pigments, etc. Examples of the pigment include carbon black-based pigments, titanium oxide-based pigments, cadmium-based pigments, lead-based pigments, chromium oxide-based pigments, iron-based pigments, and other fine particles of mica (mica) and fish scale foil.

Among the colorants, for example, carbon black is preferable in order to make the exterior material of the electricity storage device have a black appearance.

The average particle diameter of the pigment is not particularly limited and may be, for example, about 0.05 to 5 μm, preferably about 0.08 to 2 μm. The average particle size of the pigment is the median size measured by a laser diffraction / scattering particle size distribution measuring device.

The content of the pigment in the adhesive layer 2 is not particularly limited as long as the exterior material for the electricity storage device is colored, and is, for example, about 5 to 60% by mass, preferably 10 to 40% by mass.

The thickness of the adhesive layer 2 is not particularly limited as long as the base material layer 1 and the barrier layer 3 can be bonded, but the lower limit is, for example, about 1 μm or more and about 2 μm or more, and the upper limit is about 10 μm or less. And about 5 μm or less, and a preferable range is about 1 to 10 μm, about 1 to 5 μm, about 2 to 10 μm, and about 2 to 5 μm.

[Colored layer]
The colored layer is a layer provided between the base material layer 1 and the barrier layer 3 as needed (not shown). When the adhesive layer 2 is provided, a coloring layer may be provided between the base material layer 1 and the adhesive layer 2 and between the adhesive layer 2 and the barrier layer 3. Further, a colored layer may be provided outside the base material layer 1. By providing the colored layer, the exterior material for the electricity storage device can be colored.

The coloring layer can be formed, for example, by applying an ink containing a coloring agent to the surface of the base material layer 1, the surface of the adhesive layer 2, or the surface of the barrier layer 3. Known colorants such as pigments and dyes can be used as the colorant. Moreover, only one type of colorant may be used, or two or more types may be mixed and used.

Specific examples of the coloring agent contained in the coloring layer are the same as those exemplified in the section of [Adhesive layer 2].

[Barrier layer 3]
In the exterior material for an electricity storage device, the barrier layer 3 is a layer that suppresses at least entry of moisture.

The barrier layer 3 of the exterior material for an electricity storage device of the present disclosure includes the aluminum alloy foil of the present disclosure. That is, the barrier layer 3 of the exterior material for an electricity storage device of the present disclosure can be configured by the aluminum alloy foil of the present disclosure. Details of the aluminum alloy foil of the present disclosure are as described in the section “1. Aluminum alloy foil”.

[The heat-fusible resin layer 4]
In the exterior material for an electricity storage device of the present disclosure, the heat-fusible resin layer 4 corresponds to the innermost layer, and the heat-fusible resin layers are heat-fused to each other during assembly of the electricity storage device to seal the electricity storage device element. It is a layer (sealant layer) that exhibits the above.

The resin constituting the heat-fusible resin layer 4 is not particularly limited as long as it is heat-fusible, but a resin containing a polyolefin skeleton such as polyolefin or acid-modified polyolefin is preferable. The fact that the resin constituting the heat-fusible resin layer 4 contains a polyolefin skeleton can be analyzed by, for example, infrared spectroscopy, gas chromatography mass spectrometry, or the like. Further, when the resin forming the heat-fusible resin layer 4 is analyzed by infrared spectroscopy, it is preferable that a peak derived from maleic anhydride is detected. For example, when measuring the infrared spectroscopy at a maleic anhydride-modified polyolefin, a peak derived from maleic acid is detected in the vicinity of the wave number of 1760 cm ^-1 and near the wave number 1780 cm ^-1. When the heat-fusible resin layer 4 is a layer composed of a maleic anhydride-modified polyolefin, a peak derived from maleic anhydride is detected when measured by infrared spectroscopy. However, if the degree of acid modification is low, the peak may be too small to be detected. In that case, it can be analyzed by nuclear magnetic resonance spectroscopy.

Specific examples of the polyolefin include polyethylene such as low density polyethylene, medium density polyethylene, high density polyethylene, and linear low density polyethylene; ethylene-α olefin copolymers; homopolypropylene, block copolymers of polypropylene (for example, propylene and Examples thereof include polypropylene block copolymers) and polypropylene random copolymers (for example, random copolymers of propylene and ethylene); propylene-α-olefin copolymers; ethylene-butene-propylene terpolymers. Of these, polypropylene is preferred. When the polyolefin resin is a copolymer, it may be a block copolymer or a random copolymer. These polyolefin resins may be used alone or in combination of two or more.

Also, the polyolefin may be a cyclic polyolefin. The cyclic polyolefin is a copolymer of an olefin and a cyclic monomer, and examples of the olefin constituting the cyclic polyolefin include ethylene, propylene, 4-methyl-1-pentene, styrene, butadiene and isoprene. To be Examples of the cyclic monomer which is a constituent monomer of the cyclic polyolefin include cyclic alkenes such as norbornene; cyclic dienes such as cyclopentadiene, dicyclopentadiene, cyclohexadiene and norbornadiene. Among these, cyclic alkenes are preferable, and norbornene is more preferable.

ㆍ Acid-modified polyolefin is a polymer modified by block or graft polymerization of polyolefin with an acid component. As the acid-modified polyolefin, the above-mentioned polyolefin, a copolymer obtained by copolymerizing the above-mentioned polyolefin with a polar molecule such as acrylic acid or methacrylic acid, or a polymer such as a cross-linked polyolefin can be used. Examples of the acid component used for acid modification include carboxylic acids such as maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, and itaconic anhydride, or anhydrides thereof.

The acid-modified polyolefin may be an acid-modified cyclic polyolefin. The acid-modified cyclic polyolefin is a polymer obtained by copolymerizing some of the monomers constituting the cyclic polyolefin instead of the acid component, or by block-polymerizing or graft-polymerizing the acid component with respect to the cyclic polyolefin. is there. The acid-modified cyclic polyolefin is the same as described above. The acid component used for the acid modification is the same as the acid component used for the modification of the polyolefin.

Preferred acid-modified polyolefins include polyolefins modified with carboxylic acids or their anhydrides, polypropylene modified with carboxylic acids or their anhydrides, maleic anhydride-modified polyolefins, maleic anhydride-modified polypropylenes.

The heat-fusible resin layer 4 may be formed of one type of resin alone, or may be formed of a blend polymer in which two or more types of resins are combined. Furthermore, the heat-fusible resin layer 4 may be formed of only one layer, but may be formed of two or more layers of the same or different resin.

Further, the heat-fusible resin layer 4 may contain a lubricant and the like, if necessary. When the heat-fusible resin layer 4 contains a lubricant, the formability of the exterior material for an electricity storage device can be improved. The lubricant is not particularly limited, and known lubricants can be used. The lubricant may be used alone or in combination of two or more.

The lubricant is not particularly limited, but an amide lubricant is preferable. Specific examples of the lubricant include those exemplified for the base material layer 1. The lubricant may be used alone or in combination of two or more.

When a lubricant is present on the surface of the heat-fusible resin layer 4, its amount is not particularly limited, but from the viewpoint of enhancing the moldability of the electronic packaging material, it is preferably about 10 to 50 mg / m ² . More preferably, it is about 15 to 40 mg / m ² .

The lubricant present on the surface of the heat-fusible resin layer 4 may be one in which the lubricant contained in the resin constituting the heat-fusible resin layer 4 is exuded, or the lubricant of the heat-fusible resin layer 4 The surface may be coated with a lubricant.

The thickness of the heat-fusible resin layer 4 is not particularly limited as long as the heat-fusible resin layers have a function of heat-sealing each other and sealing the electricity storage device element, but for example, about 100 μm or less, preferably The thickness is about 85 μm or less, more preferably about 15 to 85 μm. For example, when the thickness of the adhesive layer 5 described later is 10 μm or more, the thickness of the heat-fusible resin layer 4 is preferably about 85 μm or less, more preferably about 15 to 45 μm. When the thickness of the adhesive layer 5 described later is less than 10 μm or when the adhesive layer 5 is not provided, the thickness of the heat-fusible resin layer 4 is preferably about 20 μm or more, more preferably 35 to 85 μm. The degree can be mentioned.

When the electrolytic solution is in contact with the heat-fusible resin layer in a high temperature environment, and the heat-fusible resin layers are heat-sealed to each other in the state where the electrolyte solution is adhered to the heat-fusible resin layer, the heat-fusion is also performed. Accordingly, from the viewpoint of exhibiting a still higher sealing strength, by the following method, in the case of measuring the temperature difference between T ₁ and the temperature difference T _2, obtained by dividing the temperature difference T ₂ at a temperature difference T ₁ value ( The ratio T ₂ / T ₁ ) is, for example, 0.55 or more, and more preferably 0.60 or more. As will be understood from the measurement contents of the temperature differences T ₁ and T ₂ below, the closer the ratio T ₂ / T ₁ is to the upper limit of 1.0, the closer the heat-fusible resin layer comes into contact with the electrolytic solution. This means that the change in the width between the start point (extrapolated melting start temperature) and the end point (extrapolated melting end temperature) of the melting peak before and after is small (see the schematic diagram of FIG. 15). That is, the value of T ₂ is usually less than or equal to the value of T ₁ . The reason for the large change in the width of the extrapolation melting start temperature and the extrapolation melting end temperature of the melting peak is that the low molecular weight resin contained in the resin that constitutes the heat-fusible resin layer contacts the electrolytic solution. By eluting in the electrolyte solution, the width of the extrapolation melting start temperature and the extrapolation melting end temperature of the melting peak of the heat-fusible resin layer after contact with the electrolyte solution is Then, it becomes small. As one of the methods for reducing the change in the width between the extrapolation melting start temperature and the extrapolation melting end temperature of the melting peak, the proportion of low molecular weight resin contained in the resin constituting the heat-fusible resin layer There is a method of adjusting.

(Measurement of temperature difference T ₁ )
In accordance with JIS K7121: 2012, a differential scanning calorimetry (DSC) is used to obtain a DSC curve for the resin used for the heat-fusible resin layer of each of the above-mentioned outer casings for electricity storage devices. From the obtained DSC curve, the temperature difference T ₁ between the extrapolation melting start temperature and the extrapolation melting end temperature of the melting peak temperature of the heat-fusible resin layer is measured.

(Measurement of temperature difference T ₂ )
In the environment of a temperature of 85 ° C., the resin used for the heat-fusible resin layer has a lithium hexafluorophosphate concentration of 1 mol / l and a volume ratio of ethylene carbonate, diethyl carbonate and dimethyl carbonate of 1: 1: After allowing it to stand in the electrolytic solution which is the solution of No. 1 for 72 hours, it is sufficiently dried. Next, in accordance with JIS K7121: 2012, a differential scanning calorimetry (DSC) is used to obtain a DSC curve for the dried polypropylene. Next, the temperature difference T ₂ between the extrapolation melting start temperature and the extrapolation melting end temperature of the melting peak temperature of the heat-fusible resin layer after drying is measured from the obtained DSC curve.

In measuring the extrapolation melting start temperature and the extrapolation melting end temperature of the melting peak temperature, a commercially available product can be used as the differential scanning calorimeter. As the DSC curve, the test sample was held at −50 ° C. for 10 minutes, then heated up to 200 ° C. at a heating rate of 10 ° C./minute (first time), held at 200 ° C. for 10 minutes, and then cooled down. The temperature was lowered to −50 ° C. at −10 ° C./min, the temperature was kept at −50 ° C. for 10 minutes, then the temperature was raised to 200 ° C. at a temperature rising rate of 10 ° C./min (second time), and the temperature was kept at 200 ° C. for 10 minutes. The DSC curve when heating up to 200 ° C. for the second time is used. Further, when measuring the temperature difference T ₁ and the temperature difference T ₂ , of the melting peaks appearing in the range of 120 to 160 ° C. in the respective DSC curves, the melting peak with the largest difference in the input of heat energy is analyzed. To do. Even if there are two or more peaks that overlap each other, only the melting peak that maximizes the difference in heat energy input is analyzed.

The extrapolation melting start temperature means the starting point of the melting peak temperature, and the melting point that maximizes the difference between the straight line extending the low temperature (65 to 75 ° C) side baseline to the high temperature side and the input of heat energy The temperature at the intersection of the curve on the low temperature side of the peak and the tangent line drawn at the point where the slope is maximum is used. The extrapolation melting end temperature means the end point of the melting peak temperature, and the high temperature side of the melting peak where the difference in the input of thermal energy is the maximum from the straight line extending the high temperature (170 ° C) side baseline to the low temperature side. The temperature at the intersection of the curve and the tangent line drawn at the point where the gradient becomes maximum.

In the exterior material for an electricity storage device of the present disclosure, the heat-fusible resin layer is heat-melted in a state where the heat-fusible resin layer is in contact with the electrolytic solution in a high temperature environment and the electrolytic solution is attached to the heat-fusible resin layer. The value (ratio T ₂ / T ₁ ) obtained by dividing the temperature difference T ₂ by the temperature difference T ₁ from the viewpoint of exerting even higher seal strength by heat fusion even when attached is as follows: For example, 0.55 or more, preferably 0.60 or more, more preferably 0.70 or more, still more preferably 0.75 or more, and a preferable range is about 0.55 to 1.0, 0.60 to For example, about 1.0, about 0.70 to 1.0, about 0.75 to 1.0. The upper limit is 1.0, for example. In order to set such a ratio T ₂ / T ₁ , for example, the type, composition, molecular weight, etc. of the resin constituting the heat-fusible resin layer 4 are adjusted.

Further, when the electrolytic solution is in contact with the heat-fusible resin layer in a high temperature environment, and the heat-fusible resin layers are heat-sealed together in a state where the electrolytic solution is attached to the heat-fusible resin layer, From the viewpoint of exhibiting even higher seal strength by fusion, the absolute value | T ₂ −T ₁ | of the temperature difference T ₂ and the temperature difference T ₁ is, for example, about 15 ° C. or less, preferably about 10 ° C. The temperature is below, more preferably about 8 ° C. or lower, still more preferably about 7.5 ° C. or lower, and the preferable range is about 0 to 15 ° C., about 0 to 10 ° C., about 0 to 8 ° C., 0 to 7. 5 ° C, 1-15 ° C, 1-10 ° C, 1-8 ° C, 1-7.5 ° C, 2-15 ° C, 2-10 ° C, 2-8 ° C, 2- The temperature is about 7.5 ° C., about 5 to 15 ° C., about 5 to 10 ° C., about 5 to 8 ° C., about 5 to 7.5 ° C. The lower limit of the absolute value of the difference | T ₂ −T ₁ | is, for example, 0 ° C., 1 ° C., 2 ° C., 5 ° C. In order to set the absolute value of the difference to | T ₂ −T ₁ |, for example, the type, composition, molecular weight, etc. of the resin forming the heat-fusible resin layer 4 are adjusted.

The temperature difference T ₁ is preferably about 29 to 38 ° C, more preferably about 32 to 36 ° C. The temperature difference T ₂ is preferably about 17 to 30 ° C, more preferably about 26 to 29 ° C. In order to set such temperature differences T ₁ and T ₂ , for example, the type, composition, molecular weight, etc. of the resin forming the heat-fusible resin layer 4 are adjusted.

[Adhesive layer 5]
In the exterior material for an electricity storage device of the present disclosure, the adhesive layer 5 is provided between the barrier layer 3 (or the corrosion resistant film) and the heat-fusible resin layer 4 as needed in order to firmly bond them. It is a layer.

The adhesive layer 5 is formed of a resin that can bond the barrier layer 3 and the heat-fusible resin layer 4. As the resin used for forming the adhesive layer 5, for example, the same resins as those exemplified for the adhesive layer 2 can be used. The resin used to form the adhesive layer 5 preferably contains a polyolefin skeleton, and examples thereof include the polyolefins and the acid-modified polyolefins described above as examples of the heat-fusible resin layer 4. The fact that the resin constituting the adhesive layer 5 contains a polyolefin skeleton can be analyzed by, for example, infrared spectroscopy, gas chromatography mass spectrometry, etc., and the analysis method is not particularly limited. Further, when the resin constituting the adhesive layer 5 is analyzed by infrared spectroscopy, it is preferable to detect a peak derived from maleic anhydride. For example, when measuring the infrared spectroscopy at a maleic anhydride-modified polyolefin, a peak derived from maleic acid is detected in the vicinity of the wave number of 1760 cm ^-1 and near the wave number 1780 cm ^-1. However, if the degree of acid modification is low, the peak may be too small to be detected. In that case, it can be analyzed by nuclear magnetic resonance spectroscopy.

From the viewpoint of firmly adhering the barrier layer 3 and the heat-fusible resin layer 4, the adhesive layer 5 preferably contains an acid-modified polyolefin. As the acid-modified polyolefin, a polyolefin modified with a carboxylic acid or an anhydride thereof, a polypropylene modified with a carboxylic acid or an anhydride thereof, a maleic anhydride modified polyolefin, and a maleic anhydride modified polypropylene are particularly preferable.

Further, from the viewpoint of making the exterior material for an electricity storage device thinner while also providing an exterior material for an electricity storage device excellent in shape stability after molding, the adhesive layer 5 is a resin composition containing an acid-modified polyolefin and a curing agent. It is more preferable that the cured product is. Preferred examples of the acid-modified polyolefin include those mentioned above.

The adhesive layer 5 is a cured product of a resin composition containing an acid-modified polyolefin and at least one selected from the group consisting of a compound having an isocyanate group, a compound having an oxazoline group, and a compound having an epoxy group. It is preferable that the cured product is a resin composition containing an acid-modified polyolefin and at least one selected from the group consisting of a compound having an isocyanate group and a compound having an epoxy group. The adhesive layer 5 preferably contains at least one selected from the group consisting of polyurethane, polyester, and epoxy resin, and more preferably contains polyurethane and epoxy resin. As the polyester, for example, an amide ester resin is preferable. The amide ester resin is generally produced by the reaction of a carboxyl group and an oxazoline group. The adhesive layer 5 is more preferably a cured product of a resin composition containing at least one of these resins and the acid-modified polyolefin. When unreacted compounds such as a compound having an isocyanate group, a compound having an oxazoline group, and a curing agent such as an epoxy resin remain in the adhesive layer 5, the presence of the unreacted substance is determined by, for example, infrared spectroscopy, It can be confirmed by a method selected from Raman spectroscopy, time-of-flight secondary ion mass spectrometry (TOF-SIMS), and the like.

Further, from the viewpoint of further improving the adhesiveness between the barrier layer 3 and the adhesive layer 5, the adhesive layer 5 is at least selected from the group consisting of an oxygen atom, a heterocycle, a C═N bond, and a C—O—C bond. It is preferably a cured product of a resin composition containing one type of curing agent. Examples of the curing agent having a heterocycle include a curing agent having an oxazoline group and a curing agent having an epoxy group. Examples of the curing agent having a C = N bond include a curing agent having an oxazoline group and a curing agent having an isocyanate group. Further, examples of the curing agent having a C—O—C bond include a curing agent having an oxazoline group, a curing agent having an epoxy group, and polyurethane. The fact that the adhesive layer 5 is a cured product of a resin composition containing these curing agents means, for example, gas chromatography mass spectrometry (GCMS), infrared spectroscopy (IR), time-of-flight secondary ion mass spectrometry (TOF). -SIMS), X-ray photoelectron spectroscopy (XPS) and the like.

The compound having an isocyanate group is not particularly limited, but from the viewpoint of effectively enhancing the adhesiveness between the barrier layer 3 and the adhesive layer 5, a polyfunctional isocyanate compound is preferable. The polyfunctional isocyanate compound is not particularly limited as long as it is a compound having two or more isocyanate groups. Specific examples of the polyfunctional isocyanate-based curing agent include pentane diisocyanate (PDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), and polymerization or nurate thereof. And the like, and their mixtures and copolymers with other polymers. Moreover, an adduct body, a burette body, an isocyanurate body, etc. are mentioned.

The content of the compound having an isocyanate group in the adhesive layer 5 is preferably in the range of 0.1 to 50% by mass, and 0.5 to 40% by mass in the resin composition constituting the adhesive layer 5. It is more preferable to be in the range. Thereby, the adhesiveness between the barrier layer 3 and the adhesive layer 5 can be effectively enhanced.

The compound having an oxazoline group is not particularly limited as long as it is a compound having an oxazoline skeleton. Specific examples of the compound having an oxazoline group include those having a polystyrene main chain and those having an acrylic main chain. Examples of commercially available products include Epocros series manufactured by Nippon Shokubai Co., Ltd.

The proportion of the compound having an oxazoline group in the adhesive layer 5 is preferably in the range of 0.1 to 50% by mass, and in the range of 0.5 to 40% by mass in the resin composition constituting the adhesive layer 5. Is more preferable. Thereby, the adhesiveness between the barrier layer 3 and the adhesive layer 5 can be effectively enhanced.

Examples of compounds having an epoxy group include epoxy resins. The epoxy resin is not particularly limited as long as it is a resin that can form a crosslinked structure by an epoxy group existing in the molecule, and a known epoxy resin can be used. The weight average molecular weight of the epoxy resin is preferably about 50 to 2000, more preferably about 100 to 1000, and further preferably about 200 to 800. In the present disclosure, the weight average molecular weight of the epoxy resin is a value measured by gel permeation chromatography (GPC), which is measured under the condition that polystyrene is used as a standard sample.

Specific examples of the epoxy resin include a glycidyl ether derivative of trimethylolpropane, bisphenol A diglycidyl ether, modified bisphenol A diglycidyl ether, novolac glycidyl ether, glycerin polyglycidyl ether, and polyglycerin polyglycidyl ether. The epoxy resin may be used alone or in combination of two or more.

The proportion of the epoxy resin in the adhesive layer 5 is preferably in the range of 0.1 to 50% by mass, and in the range of 0.5 to 40% by mass in the resin composition constituting the adhesive layer 5. Is more preferable. Thereby, the adhesiveness between the barrier layer 3 and the adhesive layer 5 can be effectively enhanced.

The polyurethane is not particularly limited, and known polyurethane can be used. The adhesive layer 5 may be, for example, a cured product of two-component curing type polyurethane.

The proportion of polyurethane in the adhesive layer 5 is preferably in the range of 0.1 to 50% by mass, and more preferably in the range of 0.5 to 40% by mass in the resin composition constituting the adhesive layer 5. More preferable. Thereby, the adhesiveness between the barrier layer 3 and the adhesive layer 5 can be effectively enhanced in an atmosphere in which a component such as an electrolytic solution that induces corrosion of the barrier layer exists.

When the adhesive layer 5 is a cured product of a resin composition containing at least one selected from the group consisting of a compound having an isocyanate group, a compound having an oxazoline group, and an epoxy resin, and the acid-modified polyolefin. The acid-modified polyolefin functions as a main agent, and the compound having an isocyanate group, the compound having an oxazoline group, and the compound having an epoxy group each function as a curing agent.

The upper limit of the thickness of the adhesive layer 5 is preferably about 50 μm or less, about 40 μm or less, about 30 μm or less, about 20 μm or less, about 5 μm or less, and the lower limit is preferably about 0.1 μm or more. , About 0.5 μm or more, and the thickness range is preferably about 0.1 to 50 μm, about 0.1 to 40 μm, about 0.1 to 30 μm, about 0.1 to 20 μm, 0. .About.1 to 5 μm, about 0.5 to 50 μm, about 0.5 to 40 μm, about 0.5 to 30 μm, about 0.5 to 20 μm, about 0.5 to 5 μm. More specifically, in the case of the adhesive exemplified in the adhesive layer 2 or a cured product of an acid-modified polyolefin and a curing agent, it is preferably about 1 to 10 μm, more preferably about 1 to 5 μm. When the resin exemplified for the heat-fusible resin layer 4 is used, it is preferably about 2 to 50 μm, more preferably about 10 to 40 μm. When the adhesive layer 5 is a cured product of the adhesive exemplified in the adhesive layer 2 or a resin composition containing an acid-modified polyolefin and a curing agent, for example, the resin composition is applied and cured by heating or the like. As a result, the adhesive layer 5 can be formed. When the resin exemplified in the heat-fusible resin layer 4 is used, the heat-fusible resin layer 4 and the adhesive layer 5 can be formed by extrusion molding, for example.

In the exterior material for an electricity storage device of the present disclosure, the adhesive layer 5 has a logarithmic decrement ΔE at 120 ° C. in a rigid pendulum measurement of, for example, 0.50 or less, 0.40 or less, 0.30 or less, 0.26 or less, 0. It is preferably 0.22 or less, and more preferably 0.20 or less. In the present disclosure, the logarithmic decay rate ΔE at 120 ° C. is, for example, 0.50 or less, 0.40 or less, 0.30 or less, 0.22 or less, 0.26 or less, and further 0.20 or less. , When the electricity storage device element is sealed by the electricity storage device exterior material, the crushing of the adhesive layer when the heat-fusible resin layers are heat-sealed is effectively suppressed, and high sealing strength is exhibited in a high temperature environment. To be done.

The logarithmic decrement at 120 ° C in the rigid pendulum measurement is an index showing the hardness of the resin in a high temperature environment of 120 ° C, and the smaller the logarithmic decrement, the higher the resin hardness. In the rigid pendulum measurement, the damping rate of the pendulum when the temperature of the resin is raised from a low temperature to a high temperature is measured. In the rigid pendulum measurement, generally, the edge portion is brought into contact with the surface of the measurement target object, and the pendulum movement is performed in the left-right direction to impart vibration to the measurement target object. In the exterior material for an electricity storage device of the present disclosure, the logarithmic decay rate in a high temperature environment of 120 ° C. is, for example, 0.50 or less, 0.40 or less, 0.30 or less, 0.26 or less, 0.22 or less, and further 0. By disposing a hard adhesive layer 5 of 20 or less between the aluminum alloy foil and the heat-fusible resin layer 4, the adhesive layer 5 is crushed (thinning) when the heat-sealing of the exterior material for an electricity storage device is performed. ) Is suppressed, and high seal strength can be exhibited in a high temperature environment.

The logarithmic decay rate ΔE is calculated by the following formula.
ΔE = [ln (A1 / A2) + ln (A2 / A3) + ... ln (An / An + 1)] / n
A: amplitude n: wave number

In the exterior material for an electricity storage device of the present disclosure, it is possible to effectively suppress the crushing of the adhesive layer 5 when the heat-fusible resin layers 4 are heat-sealed, and further to exhibit high seal strength in a high temperature environment. Therefore, the logarithmic attenuation rate ΔE at 120 ° C. is, for example, about 0.10 to 0.50, about 0.10 to 0.40, about 0.10 to 0.30, and preferably 0.10 to 0.26. The degree is about 0.10 to 0.22, preferably about 0.10 to 0.20, and more preferably about 0.10 to 0.16. In order to set the logarithmic decrement ΔE, for example, the type, composition, molecular weight, etc. of the resin forming the adhesive layer 5 are adjusted.

In the measurement of the logarithmic decrement ΔE, a commercially available rigid pendulum type physical property tester was used, and a cylindrical cylinder edge was used as an edge portion to be pressed against the adhesive layer 5, the initial amplitude was 0.3 degree, and the temperature was from 30 ° C to 200 ° C. A rigid pendulum physical property test is performed on the adhesive layer 5 at a temperature rising rate of 3 ° C./min in the range. Then, based on the logarithmic decrement at 120 ° C., a standard for suppressing the collapse of the adhesive layer 5 and improving the seal strength by heat fusion in a high temperature environment was set. Regarding the adhesive layer for measuring the logarithmic decrement ΔE, the exterior material for an electricity storage device was immersed in 15% hydrochloric acid to dissolve the base material layer and the aluminum alloy foil, and only the adhesive layer and the heat-fusible resin layer were formed. Dry the resulting sample sufficiently and use it as the measurement target.

It is also possible to acquire the exterior material for an electricity storage device from the electricity storage device and measure the logarithmic decrement ΔE of the adhesive layer 5. When the exterior material for an electricity storage device is acquired from the electricity storage device and the logarithmic attenuation rate ΔE of the adhesive layer 5 is measured, a sample is cut out from the top surface portion where the exterior material for the electricity storage device is not stretched by molding and is used as a measurement target.

Further, in the exterior material for an electricity storage device of the present disclosure, the heat-fusible resin layers of the laminate constituting the exterior material for an electricity storage device are opposed to each other, and the temperature is 190 ° C., the surface pressure is 0.5 MPa, and the time is 3 seconds. After heating and pressing in the laminating direction under the conditions, the residual ratio of the thickness of the adhesive layer is preferably 70% or more, more preferably 80% or more, and the preferable range is 70 to 95%, 80 to 95% is mentioned. The upper limit of the remaining ratio of the thickness is about 95%, for example. The remaining ratio of the thickness is a value measured by the following method. In order to set the remaining ratio of the thickness, for example, the type, composition, molecular weight, etc. of the resin forming the adhesive layer 5 are adjusted.

<Measurement of residual ratio of thickness of adhesive layer>
A test sample is prepared by cutting the exterior material for an electricity storage device into a length of 150 mm and a width of 60 mm. Next, the heat-fusible resin layers of the test sample are made to face each other. Then, in that state, using a metal plate having a width of 7 mm, heat and pressure were applied from both sides of the test sample in the laminating direction at a temperature of 190 ° C., a surface pressure of 0.5 MPa, and a time of 3 seconds to perform heat fusion. The heat-resistant resin layers are fused with each other. Next, the heat-fused portion of the test sample is cut in the stacking direction using a microtome, and the thickness of the adhesive layer is measured on the exposed cross section. Similarly, the test sample before heat fusion is cut in the stacking direction using a microtome, and the thickness of the adhesive layer is measured on the exposed cross section. The ratio of the thickness of the adhesive layer after thermal fusion to the thickness of the adhesive layer before thermal fusion is calculated, and the residual ratio (%) of the thickness of the adhesive layer is measured. The thickness of the adhesive layer is measured in the vicinity of the end of the exterior material for an electricity storage device, where the thickness is constant.

It is also possible to acquire the exterior material for an electricity storage device from the electricity storage device and measure the remaining ratio of the thickness of the adhesive layer 5. When an exterior material for an electricity storage device is obtained from an electricity storage device and the remaining ratio of the thickness of the adhesive layer 5 is measured, a sample is cut out from the top surface portion where the exterior material for the electricity storage device is not stretched by molding and is used as a measurement target. .

The logarithmic decrement ΔE of the adhesive layer 5 can be adjusted by, for example, the melt mass flow rate (MFR) of the resin forming the adhesive layer 5, the molecular weight, the melting point, the softening point, the molecular weight distribution, and the crystallinity.

[Surface coating layer 6]
The exterior material for an electricity storage device of the present disclosure is, if necessary, on the base material layer 1 (base material layer 1 for the purpose of at least one of improvement in designability, electrolytic solution resistance, scratch resistance, moldability, etc.). The surface coating layer 6 may be provided on the side opposite to the barrier layer 3). The surface coating layer 6 is a layer located on the outermost layer side of the exterior material for an electricity storage device when the electricity storage device is assembled using the exterior material for an electricity storage device.

The surface coating layer 6 can be formed of a resin such as polyvinylidene chloride, polyester, polyurethane, acrylic resin, or epoxy resin.

When the resin forming the surface coating layer 6 is a curable resin, the resin may be either a one-component curing type or a two-component curing type, but is preferably a two-component curing type. Examples of the two-component curing type resin include two-component curing type polyurethane, two-component curing type polyester, and two-component curing type epoxy resin. Among these, two-component curing type polyurethane is preferable.

The two-component curing type polyurethane includes, for example, a polyurethane containing a base compound containing a polyol compound and a curing agent containing an isocyanate compound. Preferred is a two-component curing type polyurethane having a polyol such as a polyester polyol, a polyether polyol, and an acrylic polyol as a main agent and an aromatic or aliphatic polyisocyanate as a curing agent. Further, as the polyol compound, it is preferable to use a polyester polyol having a hydroxyl group at the side chain in addition to the hydroxyl group at the terminal of the repeating unit. Since the surface coating layer 6 is formed of polyurethane, excellent electrolytic solution resistance is imparted to the exterior material for an electricity storage device.

The surface coating layer 6 is provided on at least one of the surface and the inside of the surface coating layer 6 depending on the surface coating layer 6 and the functionality to be provided on the surface thereof, if necessary, and the above-mentioned lubricant or anti-reflective agent. It may contain additives such as a blocking agent, a matting agent, a flame retardant, an antioxidant, a tackifier, and an antistatic agent. Examples of the additive include fine particles having an average particle diameter of about 0.5 nm to 5 μm. The average particle diameter of the additive is a median diameter measured by a laser diffraction / scattering type particle diameter distribution measuring device.

The additive may be an inorganic substance or an organic substance. Also, the shape of the additive is not particularly limited, and examples thereof include spherical shape, fibrous shape, plate shape, amorphous shape, and scale shape.

Specific examples of the additive include talc, silica, graphite, kaolin, montmorillonite, mica, hydrotalcite, silica gel, zeolite, aluminum hydroxide, magnesium hydroxide, zinc oxide, magnesium oxide, aluminum oxide, neodymium oxide, antimony oxide. , Titanium oxide, cerium oxide, calcium sulfate, barium sulfate, calcium carbonate, calcium silicate, lithium carbonate, calcium benzoate, calcium oxalate, magnesium stearate, alumina, carbon black, carbon nanotubes, high melting point nylon, acrylate resin, Examples include crosslinked acrylic, crosslinked styrene, crosslinked polyethylene, benzoguanamine, gold, aluminum, copper and nickel. The additives may be used alone or in combination of two or more. Among these additives, silica, barium sulfate and titanium oxide are preferable from the viewpoint of dispersion stability and cost. Further, the additives may be subjected to various surface treatments such as insulation treatment and high dispersibility treatment on the surface.

The method of forming the surface coating layer 6 is not particularly limited, and examples thereof include a method of applying a resin forming the surface coating layer 6. When the surface coating layer 6 contains an additive, a resin mixed with the additive may be applied.

The thickness of the surface coating layer 6 is not particularly limited as long as it exhibits the above-mentioned functions as the surface coating layer 6, and is, for example, about 0.5 to 10 μm, preferably about 1 to 5 μm.

3. Method for manufacturing exterior material for power storage device The method for manufacturing the exterior material for power storage device is not particularly limited as long as a laminate in which each layer of the exterior material for power storage device of the present disclosure is laminated is obtained, and at least a base material. The method includes a step of laminating the layer 1, the barrier layer 3, and the heat-fusible resin layer 4 in this order. As described above, the aluminum alloy foil of the present disclosure can be used as the barrier layer 3.

The following is an example of a method for manufacturing the exterior material for an electricity storage device of the present disclosure. First, a laminated body in which the base material layer 1, the adhesive layer 2, and the barrier layer 3 are laminated in order (hereinafter, also referred to as “laminated body A”) is formed. Specifically, the laminate A is formed by applying an adhesive used for forming the adhesive layer 2 on the base material layer 1 or on the barrier layer 3 whose surface has been subjected to chemical conversion treatment, if necessary, by a gravure coating method. This can be performed by a dry laminating method in which the barrier layer 3 or the base material layer 1 is laminated and the adhesive layer 2 is cured after being applied and dried by a coating method such as a roll coating method.

Next, the heat-fusible resin layer 4 is laminated on the barrier layer 3 of the laminate A. When the heat-fusible resin layer 4 is directly laminated on the barrier layer 3, the heat-fusible resin layer 4 is laminated on the barrier layer 3 of the laminate A by a method such as a thermal laminating method or an extrusion laminating method. do it. When the adhesive layer 5 is provided between the barrier layer 3 and the heat-fusible resin layer 4, for example, (1) the adhesive layer 5 and the heat-fusible resin layer are provided on the barrier layer 3 of the laminate A. Method of laminating by extruding 4 (coextrusion laminating method, tandem laminating method), (2) Separately, a laminated body in which the adhesive layer 5 and the heat-fusible resin layer 4 are laminated is formed, and the laminated body A By a thermal lamination method, or by forming a laminated body in which the adhesive layer 5 is laminated on the barrier layer 3 of the laminated body A, and by using the thermal fusion bonding resin layer 4 and the thermal lamination method. Method of Laminating, (3) While pouring the melted adhesive layer 5 between the barrier layer 3 of the laminate A and the heat-fusible resin layer 4 which is formed into a sheet in advance, the adhesive layer 5 is interposed. Method for laminating the laminate A and the heat-fusible resin layer 4 (sandwich lamine (4), (4) the barrier layer 3 of the laminate A is laminated by a solution coating method for forming an adhesive layer 5 with an adhesive, followed by drying, or a baking method. Examples thereof include a method of laminating the heat-fusible resin layer 4 which is previously formed into a sheet shape on the above.

When the surface coating layer 6 is provided, the surface coating layer 6 is laminated on the surface of the base material layer 1 opposite to the barrier layer 3. The surface coating layer 6 can be formed, for example, by applying the above-mentioned resin forming the surface coating layer 6 to the surface of the base material layer 1. The order of the step of laminating the barrier layer 3 on the surface of the base material layer 1 and the step of laminating the surface coating layer 6 on the surface of the base material layer 1 is not particularly limited. For example, after forming the surface coating layer 6 on the surface of the base material layer 1, the barrier layer 3 may be formed on the surface of the base material layer 1 opposite to the surface coating layer 6.

As described above, the surface coating layer 6 / if necessary, the base material layer 1 / the adhesive layer 2 / barrier layer 3 / the adhesive layer 5 / thermal fusion bonding which is provided as needed. Although a laminate including the functional resin layer 4 in this order is formed, it may be further subjected to a heat treatment in order to strengthen the adhesiveness of the adhesive layer 2 and the adhesive layer 5 provided as necessary.

In the exterior material for an electricity storage device, each layer constituting the laminate may be subjected to surface activation treatment such as corona treatment, blast treatment, oxidation treatment, or ozone treatment, if necessary, to improve the processability. . For example, by performing corona treatment on the surface of the base material layer 1 opposite to the barrier layer 3, it is possible to improve the printability of the ink on the surface of the base material layer 1.

4. Application of Exterior Material for Energy Storage Device The exterior material for an energy storage device according to the present disclosure is used for a package for hermetically housing an energy storage device element such as a positive electrode, a negative electrode, and an electrolyte. That is, an electricity storage device can be prepared by accommodating an electricity storage device element including at least a positive electrode, a negative electrode, and an electrolyte in a package formed of the electricity storage device exterior material of the present disclosure.

Specifically, in an electricity storage device element having at least a positive electrode, a negative electrode, and an electrolyte, in the exterior material for an electricity storage device of the present disclosure, in a state in which metal terminals connected to each of the positive electrode and the negative electrode are projected outward. To cover the periphery of the electricity storage device element so that a flange portion (a region where the heat-fusible resin layers are in contact with each other) can be formed, and heat-seal and seal the heat-fusible resin layers of the flange portion. Thus, an electricity storage device using the exterior material for an electricity storage device is provided. In the case where the electricity storage device element is housed in a package formed of the electricity storage device exterior material of the present disclosure, the heat-fusible resin portion of the electricity storage device exterior material of the present disclosure is inside (a surface that contacts the electricity storage device element). ), And a package is formed.

The exterior material for an electricity storage device of the present disclosure can be suitably used for an electricity storage device such as a battery (including a capacitor, a capacitor, etc.). Further, the exterior material for an electricity storage device of the present disclosure may be used in either a primary battery or a secondary battery, but is preferably a secondary battery. The type of secondary battery to which the exterior material for an electricity storage device of the present disclosure is applied is not particularly limited, and examples thereof include a lithium ion battery, a lithium ion polymer battery, an all-solid-state battery, a lead storage battery, a nickel-hydrogen storage battery, and a nickel-hydrogen storage battery. Examples thereof include a cadmium storage battery, a nickel / iron storage battery, a nickel / zinc storage battery, a silver oxide / zinc storage battery, a metal-air battery, a polyvalent cation battery, a capacitor and a capacitor. Among these secondary batteries, lithium ion batteries and lithium ion polymer batteries are mentioned as suitable targets to which the exterior material for an electricity storage device of the present disclosure is applied.

The present disclosure will be described in detail below with reference to examples and comparative examples. However, the present disclosure is not limited to the embodiments.

[Example 1]
<Manufacture of aluminum alloy foil>
Using an aluminum alloy consisting of Mn 0.10 mass%, Mg 2.20 mass%, Fe 0.40 mass%, Cu 0.10 mass%, Si 0.00 mass%, Cr 0.00 mass%, Zn 0.00 mass% and the balance of Al. In the same manner as the known aluminum alloy manufacturing method, a 40 μm thick aluminum alloy foil was obtained through the steps of melting, homogenizing treatment, hot rolling, cold rolling, intermediate annealing, cold rolling, and final annealing. The obtained aluminum alloy foil has the composition described in Example 1 in Table 1. The manufacturing conditions of the aluminum alloy foil can be referred to, for example, the description in JP-A-2005-163077.

<Manufacture of exterior materials for power storage devices>
Polyethylene terephthalate film (12 μm) / adhesive layer (two-component curing type urethane adhesive (polyol compound and aromatic isocyanate compound), thickness 3 μm) / biaxially stretched nylon film (thickness 15 μm) are laminated in this order as a base material layer. The laminated film thus prepared was prepared. Next, on the biaxially stretched nylon film (thickness: 15 μm) of the base material layer, the above aluminum alloy foil (having the composition shown in Table 1 and having a thickness of A barrier layer having a thickness of 40 μm) was laminated by a dry lamination method. Specifically, a two-component curing type is used on one surface of an aluminum alloy foil having a corrosion resistant film (acid resistant film (a film formed by chromate treatment and a chromium content of 30 mg / m ² )) formed on both surfaces. A urethane adhesive (polyol compound and aromatic isocyanate compound) was applied to form an adhesive layer (thickness 3 μm after curing) on the aluminum alloy foil. Then, after laminating the adhesive layer on the aluminum alloy foil and the biaxially stretched nylon film, aging treatment was carried out to produce a laminate of base material layer / adhesive layer / barrier layer. Next, maleic anhydride-modified polypropylene (thickness 40 μm) as an adhesive layer and polypropylene (thickness 40 μm) as a heat-fusible resin layer are coextruded on the barrier layer of the obtained laminate. Thus, the adhesive layer / heat-fusible resin layer was laminated on the barrier layer. Next, the obtained laminate is aged and heated to give a polyethylene terephthalate film (12 μm) / adhesive layer (3 μm) / biaxially stretched nylon film (15 μm) / adhesive layer (3 μm) / barrier layer ( 40 μm) / adhesive layer (40 μm) / heat-fusible resin layer (40 μm) were laminated in this order to obtain a packaging material for an electricity storage device.

In Examples 1 and 2, the maleic anhydride-modified polypropylene used for the adhesive layer was different, and the logarithmic decrement ΔE at 120 ° C. (using a rigid pendulum type physical property tester shown in Table 3) was used. (Measured value). Further, in Examples 1 and 2, the heat-fusible resin layer is a melting peak of the heat-fusible resin layer, which is measured by the method described below by adjusting the amount of the low molecular weight component in polypropylene. The value (T ₂ / T ₁ ) obtained by dividing the temperature difference T ₂ between the temperature start point (extrapolated melting start temperature) and the end point (extrapolated melting end temperature) by the temperature difference T ₁ is adjusted. ing.

Erucamide was present as a lubricant on both sides of the exterior material for the electricity storage device to form a lubricant layer. The same applies to the following examples and comparative examples.

[Example 2]
The composition of the aluminum alloy foil is 0.17 mass% Mn, 0.20 mass% Mg, 0.09 mass% Fe, 0.00 mass% Cu, 0.00 mass% Si, 0.00 mass% Cr, 0.00 mass% Zn, and the balance of Al. An outer casing material for an electricity storage device was obtained in the same manner as in Example 1 except for the above.

[Comparative Example 1]
The composition of the aluminum alloy foil is Mn 0.00 mass%, Mg 0.00 mass%, Fe 1.20 mass%, Cu 0.05 mass%, Si 0.00 mass%, Cr 0.00 mass%, Zn 0.00 mass%, balance Al. An outer casing material for an electricity storage device was obtained in the same manner as in Example 1 except for the above.

[Comparative Example 2]
The composition of the aluminum alloy foil is Mn 0.16% by mass, Mg 0.10% by mass, Fe 0.09% by mass, Cu 0.00% by mass, Si 0.00% by mass, Cr 0.00% by mass, Zn 0.00% by mass, balance Al. An outer casing material for an electricity storage device was obtained in the same manner as in Example 1 except for the above.

<Evaluation of corrosion resistance>
The electric storage device exterior materials used in Examples 1 and 2 and Comparative Examples 1 and 2 were cut into a rectangle having a length of 50 mm and a width of 20 mm. Next, of the four end faces of the exterior material, three end faces except one short side are heat-welded to each side so that a 5 mm rectangular inner surface is overlapped with a polyethylene film having a width of 10 mm, and each end face is covered. It was folded back at a position of 10 mm from the lower part in the direction, and further folded back in half in the direction in which the polyethylene films of the two long side end faces were overlapped at the center in the width direction, and further pressed at a pressure of 3 MPa to obtain a test sample. Incidentally, the evaluation of the corrosion resistance in the test sample is performed at the cross portion formed by the bent line in the width direction and the bent line in the length direction of the exterior material, and the end portion of the test sample that is not immersed in the electrolytic solution is the working electrode. The aluminum alloy foil was exposed for connection. Next, as shown in the schematic diagram of FIG. 9, the test sample exterior material was set as a working electrode and metallic lithium Li (diameter 15 mm × thickness 0.35 mm) was set as a counter electrode, and an electrolyte solution X (1 mol / l LiPF ₆ and , Mixed with ethylene carbonate, diethyl carbonate and dimethyl carbonate (volume ratio 1: 1: 1). In this state, under a 20 ° C. environment, a voltage of 0.1 V was applied for 24 hours to measure the total charge (C). The results are shown in Table 2. Furthermore, the appearance of the exposed portion M of the obtained test sample was observed with a digital microscope (magnification: 200 times). The obtained images are shown in FIG. 5 (Example 1), FIG. 6 (Example 2), FIG. 7 (Comparative Example 1), and FIG. 8 (Comparative Example 2), respectively.

The aluminum alloy foils of Examples 1 and 2 have Mg contents of 2.20% by mass and 0.20% by mass, and as shown in Table 2, the total charge in the corrosion resistance evaluation is -6. It is as small as 6 × 10 ³ C and −9.2 × 10 ³ C, and it can be seen that the corrosion when electric current is generated with the electrolytic solution adhered is effectively suppressed. Since the corroded portions are very small in the microscope images (FIGS. 5 and 6) of the bent intersection points of the exterior materials after the corrosion resistance evaluations of Examples 1 and 2, the corrosion images of Examples 1 and 2 are also shown. It can be seen that the exterior material is effectively suppressed from corrosion when energization occurs with the electrolytic solution attached. On the other hand, as shown in Table 2, the exterior materials of Comparative Examples 1 and 2 have large total charges in the corrosion resistance evaluation of −2.1 × 10 ⁴ C and −1.8 × 10 ⁴ C, It can be seen that the effect of suppressing corrosion is poor when current is applied while the electrolyte is attached. Corrosion is observed in the microscope images (FIGS. 7 and 8) of the folding intersection points of the exterior materials after the corrosion resistance evaluations of Comparative Example 1 and Comparative Example 2 also suggest that the exteriors of Comparative Example 1 and Comparative Example 2 are obtained. It can be seen that the material is inferior in the effect of suppressing corrosion.

<Measurement of logarithmic attenuation rate ΔE of adhesive layer>
The outer packaging material for an electricity storage device of Example 1 and Example 2 obtained above was cut into a rectangle having a width (TD: Transverse Direction) of 15 mm x a length (MD: Machine Direction) of 150 mm, and a test sample (for an electricity storage device). The exterior material was used as 10). The MD of the exterior material for an electricity storage device corresponds to the rolling direction (RD) of the aluminum alloy foil, and the TD of the exterior material for an electricity storage device corresponds to the TD of the aluminum alloy foil. (RD) can be determined by the rolling pattern. When the MD of the exterior material for an electricity storage device cannot be specified due to the rolled grain of the aluminum alloy foil, it can be specified by the following method. As a method for confirming the MD of the exterior material for an electricity storage device, the sea-island structure is observed by observing the cross section of the heat-fusible resin layer of the exterior material for an electricity storage device with an electron microscope, and the The direction parallel to the cross section in which the average diameter of the island shape in the direction is maximum can be determined as MD. Specifically, the angle in the longitudinal direction of the heat-fusible resin layer is changed by 10 degrees from the direction parallel to the longitudinal cross section, and each angle is changed to the direction perpendicular to the longitudinal cross section. The cross-sections (total of 10 cross-sections) are observed with electron micrographs to confirm the sea-island structure. Next, the shape of each individual island is observed in each cross section. Regarding the shape of each island, a straight line distance connecting the leftmost end in the direction perpendicular to the thickness direction of the heat-fusible resin layer and the rightmost end in the vertical direction is defined as a diameter y. In each cross section, the average of the top 20 diameters y in the descending order of the diameter y of the island shape is calculated. The direction parallel to the cross section in which the average of the diameter y of the island shape is the largest is determined as MD. FIG. 13 shows a schematic diagram for explaining the method of measuring the logarithmic decrement ΔE by the rigid pendulum measurement. Using a rigid pendulum type physical property tester (model number: RPT-3000W, manufactured by A & D Co., Ltd.), FRB-100 is used for the frame of the pendulum 30, RBP-060 is used for the cylindrical cylinder edge 30a at the edge, and cold heat is applied. CHB-100, a vibration displacement detector 32, and a weight 33 were used for the block 31, and the initial amplitude was set to 0.3 degree. The measurement surface (adhesive layer) of the test sample is placed on the cooling / heating block 31 so that the axial direction of the cylindrical cylinder edge 30a with the pendulum 30 is orthogonal to the MD direction of the test sample on the measurement surface. installed. Further, in order to prevent the test sample from floating and warping during the measurement, a tape was attached to a portion of the test sample that does not affect the measurement result and fixed on the cooling / heating block 31. The cylindrical cylinder edge 30a was brought into contact with the surface of the adhesive layer. Next, the cooling block 31 was used to measure the logarithmic decay rate ΔE of the adhesive layer in the temperature range of 30 ° C. to 200 ° C. at a temperature rising rate of 3 ° C./min. The logarithmic decrement ΔE when the surface temperature of the adhesive layer of the test sample (energy storage device exterior material 10) was 120 ° C. was adopted. (The test sample once measured was not used, but an average value measured three times (N = 3) using a freshly cut one was used.) For the adhesive layer, Example 1 and Example obtained above were used. The exterior material for an electricity storage device of Example 2 was dipped in 15% hydrochloric acid to dissolve the base material layer and the aluminum alloy foil, and the test sample including only the adhesive layer and the heat-fusible resin layer was sufficiently dried to give a logarithm. The attenuation rate ΔE was measured. Table 3 shows the logarithmic decay rate ΔE at 120 ° C., respectively. (Note that the logarithmic decay rate ΔE is calculated by the following formula.)
ΔE = [ln (A1 / A2) + ln (A2 / A3) +. ．． + Ln (An / An + 1)] / n
A: amplitude n: wave number

<Measurement of residual ratio of thickness of adhesive layer>
The outer packaging material for an electricity storage device of Example 1 and Example 2 obtained above was cut into a length of 150 mm × a width of 60 mm to prepare a test sample (exterior material 10 for an electricity storage device). Next, the heat-fusible resin layers of the test samples of the same size made from the same exterior material for the electricity storage device were opposed to each other. Then, in that state, using a metal plate having a width of 7 mm, the test sample was heated from both sides in the stacking direction at a temperature of 190 ° C., a surface pressure (0.5 MPa) shown in Table 3, and a time of 3 seconds. The pressure was applied to heat-bond the heat-fusible resin layers to each other. Next, the heat-fused portion of the test sample was cut in the laminating direction using a microtome, and the thickness of the adhesive layer was measured on the exposed cross section. Similarly, for the test sample before heat fusion, the thickness of the adhesive layer was measured on the exposed cross section by cutting in the laminating direction using a microtome in the same manner. The ratio of the thickness of the adhesive layer after heat fusion to the thickness of the adhesive layer before heat fusion was calculated, and the remaining ratio (%) of the thickness of the adhesive layer was measured. The results are shown in Table 3.

<Measurement of seal strength in 25 ° C environment or 140 ° C environment>
The electrical storage device exterior materials of Examples 1 and 2 obtained above were cut into a rectangle having a width of 60 mm and a length of 150 mm to obtain a test sample (electrical storage device exterior material 10). Next, as shown in FIG. 10, the test sample was folded back at the center P in the lengthwise direction and the heat-fusible resin layers were opposed to each other. Next, using a metal plate 20 having a width of 7 mm, the surface pressure was 1.0 MPa, the time was 1 second, and the temperature was 190 ° C., the length of the test sample was 7 mm (width of the metal plate), and the entire width direction (that is, 60 mm). In, the heat-fusible resin layers were heat-bonded to each other. Next, using a double-edged sample cutter, the test sample was cut into a width of 15 mm as shown in FIG. In FIG. 11, the heat-sealed region is indicated by S. Next, as shown in FIG. 12, using a tensile tester so as to achieve T-shaped peeling, in an environment of a temperature of 25 ° C. or an environment of a temperature of 140 ° C., a pulling speed of 300 mm / min, a peeling angle of 180 °, Under the condition that the distance between chucks is 50 mm, the heat-bonded interface is peeled off, and the maximum peeling strength (N / 15 mm) for 1.5 seconds from the start of tensile strength measurement is determined by the seal strength in an environment of 25 ° C. And the seal strength in a 140 ° C. environment. The tensile test at each temperature was carried out in a constant temperature bath, and the test sample was attached to the chuck in the constant temperature bath at a predetermined temperature and held for 2 minutes before starting the measurement. Each seal strength is an average value (n = 3) measured in the same manner by producing three test samples. The results are shown in Table 3.

From the results shown in Table 3, in the exterior materials for electricity storage devices of Example 1 and Example 2, 120 in the rigid pendulum measurement of the adhesive layer located between the aluminum alloy foil and the heat-fusible resin layer. The logarithmic decrement ΔE at ℃ is 0.50 or less, crushing of the adhesive layer when heat-sealing the heat-fusible resin layers is effectively suppressed, and high sealing strength is exhibited in a high temperature environment. I know what to do. Furthermore, in the outer casing material for an electricity storage device of Example 1, the logarithmic decay rate ΔE is 0.20 or less, and the crushing of the adhesive layer when the heat-fusible resin layers are heat-sealed more effectively. It can be seen that it is suppressed and exhibits higher seal strength in a high temperature environment.

<Measurement of extrapolation melting start temperature and extrapolation melting end temperature of melting peak temperature>
The extrapolation melting start temperature and the extrapolation melting end temperature of the melting peak temperature were measured for the polypropylene used for the heat-fusible resin layer of the exterior materials for electricity storage devices of Examples 1 and 2 by the following method. Then, the temperature difference T ₁ , T ₂ between the extrapolation melting start temperature and the extrapolation melting end temperature is measured, and the ratio (T ₂ / T ₁ ) of these is obtained from the values of the obtained temperature differences T ₁ , T _2. And the absolute value of the difference | T ₂ −T ₁ | was calculated. The results are shown in Table 4.

(Measurement of temperature difference T ₁ )
According to JIS K7121: 2012, the differential scanning calorimetry (DSC) was used to determine the polypropylene used for the heat-fusible resin layer of the outer casing material for an electricity storage device in Examples 1 and 2 above. A DSC curve was obtained. From the obtained DSC curve, the temperature difference T ₁ between the extrapolation melting start temperature and the extrapolation melting end temperature of the melting peak temperature of the heat-fusible resin layer was measured.

(Measurement of temperature difference T ₂ )
In an environment of a temperature of 85 ° C., the polypropylene used for the heat-fusible resin layer was prepared by using lithium hexafluorophosphate having a concentration of 1 mol / l and a volume ratio of ethylene carbonate, diethyl carbonate and dimethyl carbonate of 1: 1: It was allowed to stand for 72 hours in the electrolytic solution as the solution of No. 1 and then sufficiently dried. Next, a DSC curve was obtained for the dried polypropylene using differential scanning calorimetry (DSC) in accordance with JIS K7121: 2012. Next, from the obtained DSC curve, the temperature difference T ₂ between the extrapolation melting start temperature and the extrapolation melting end temperature of the melting peak temperature of the dried heat-fusible resin layer was measured.

In measuring the extrapolated melting start temperature and the extrapolated melting end temperature of the melting peak temperature, Q200 manufactured by TA Instruments was used as a differential scanning calorimeter. As the DSC curve, the test sample was held at −50 ° C. for 10 minutes, then heated up to 200 ° C. at a heating rate of 10 ° C./minute (first time), held at 200 ° C. for 10 minutes, and then cooled down. After decreasing the temperature to -50 ° C in -10 ° C minutes and holding at -50 ° C for 10 minutes, the temperature was raised to 200 ° C at a temperature rising rate of 10 ° C / minute (second time) and kept at 200 ° C for 10 minutes. The DSC curve when the temperature was raised to 200 ° C. for the second time was used. Further, when measuring the temperature difference T ₁ and the temperature difference T ₂ , of the melting peaks appearing in the range of 120 to 160 ° C. in the respective DSC curves, the melting peak with the largest difference in the input of heat energy is analyzed. went. Even when two or more peaks were overlapped with each other, the analysis was performed only on the melting peak that maximizes the difference in input of thermal energy.

The extrapolation melting start temperature means the starting point of the melting peak temperature, and the melting point that maximizes the difference between the straight line extending the low temperature (65 to 75 ° C) side baseline to the high temperature side and the input of heat energy The temperature at the intersection of the curve on the low temperature side of the peak and the tangent line drawn at the point where the gradient becomes maximum was taken. The extrapolation melting end temperature means the end point of the melting peak temperature, and the high temperature side of the melting peak where the difference in the input of thermal energy is the maximum from the straight line extending the high temperature (170 ° C) side baseline to the low temperature side. The temperature at the intersection of the curve and the tangent line drawn at the point where the gradient becomes maximum was taken.

<Measurement of seal strength before contact with electrolyte>
In <Measurement of seal strength after contact with electrolytic solution> below, tensile strength (seal strength) was measured in the same manner except that the electrolytic solution was not injected into the test sample. The maximum tensile strength until the heat-sealed portion is completely peeled off is defined as the sealing strength before contact with the electrolytic solution. In Table 5, the seal strength before contact with the electrolytic solution is described as the seal strength when the contact time of the electrolytic solution at 85 ° C. is 0 h.

<Measurement of seal strength after contact with electrolyte>
As shown in the schematic diagram of FIG. 14, the outer packaging material for an electricity storage device of Example 1 and Example 2 obtained above was cut into a rectangle having a width (x direction) of 100 mm and a length (z direction) of 200 mm. It was used as a test sample (exterior material 10 for electricity storage device) (FIG. 14 a). The test sample (exterior material 10 for electricity storage device) was folded back at the center in the z direction so that the heat-fusible resin layer sides were overlapped (FIG. 14b). Next, both ends in the x direction of the folded back test sample were sealed by heat sealing (temperature 190 ° C., surface pressure 2.0 MPa, time 3 seconds), and formed into a bag shape having one opening E (FIG. 14c). Next, an electrolyte solution (concentration of lithium hexafluorophosphate is 1 mol / l and volume ratio of ethylene carbonate, diethyl carbonate and dimethyl carbonate is 1: 1: 1 from the opening E of the test sample formed in the shape of a bag. 6 g of the solution of No. 1) was injected (FIG. 14 d), and the end of the opening E was sealed by heat sealing (temperature 190 ° C., surface pressure 2.0 MPa, time 3 seconds) (FIG. 14 e). Next, the folded back portion of the bag-shaped test sample was turned down, and the bag was allowed to stand in an environment of a temperature of 85 ° C. for a predetermined storage time (time for contacting with electrolyte solution, 0 hour, 24 hours, 72 hours). The end of the test sample was then cut (Fig. 14e) and the electrolyte was drained. Next, with the electrolytic solution attached to the surface of the heat-fusible resin layer, the upper and lower surfaces of the test sample were sandwiched between metal plates 20 (7 mm width), and the temperature was 190 ° C., the surface pressure was 1.0 MPa, and the time was 3 seconds. The heat-fusible resin layers were heat-fused under the conditions (FIG. 14f). Next, the test sample was cut into a width of 15 mm with a double-edged sample cutter so that the seal strength at a width (x direction) of 15 mm could be measured (Fig. 14f, g). Next, using a tensile tester (manufactured by Shimadzu Corporation, AGS-xplus (trade name)) so as to achieve T-shaped peeling, at a temperature of 25 ° C., a pulling speed of 300 mm / min, a peeling angle of 180 °, and a chuck. The tensile strength (seal strength) was measured by peeling the heat-sealed interface under the condition that the distance was 50 mm (FIG. 12). The maximum tensile strength until the heat-sealed portion was completely peeled (the distance until peeling was 7 mm, which is the width of the metal plate) was taken as the seal strength after contact with the electrolytic solution.

Table 5 shows the retention rate (%) of the seal strength after contact with the electrolytic solution, with the seal strength before contact with the electrolytic solution as the standard (100%).

From the results shown in Table 4, the value obtained by dividing the temperature difference T ₂ by the temperature difference T ₁ is 0.55 or more in the exterior materials for electricity storage devices of Example 1 and Example 2, and the high temperature environment The electrolytic solution is in contact with the heat-fusible resin layer, and even when the heat-fusible resin layers are heat-sealed to each other in a state in which the electrolyte solution is adhered to the heat-fusible resin layer, it is high due to heat fusion. It can be seen that the seal strength is exhibited. Furthermore, in the exterior material for an electricity storage device of Example 1, the value obtained by dividing the temperature difference T ₂ by the temperature difference T ₁ is 0.60 or more, and the electrolytic solution is applied to the heat fusible resin layer in a high temperature environment. It can be seen that even when the heat-fusible resin layers are heat-sealed in the state where the electrolytic solution is attached to the heat-fusible resin layer, the heat-sealing resin exhibits higher seal strength. .

As described above, the present disclosure provides the invention of the following aspects.
Item 1. An aluminum alloy foil having a Mg content of 0.20% by mass or more and 5.50% by mass or less for use as an exterior material for an electricity storage device.
Item 2. Si content is 0.40 mass% or less, Fe content is 0.70 mass% or less, Cu content is 0.20 mass% or less, Mn content is 1.00 mass% or less, and Cr content is 0.10 mass% or less. 50 mass% or less, Zn content is 0.25 mass% or less, other unavoidable impurities are individually 0.05 mass% or less and 0.15 mass% or less in total, and the balance is Al, Item 1. The aluminum alloy foil according to item 1.
Item 3. Item 3. The aluminum alloy foil according to

Item

1 or 2, which has a thickness of 200 μm or less.
Item 4. At least, a base layer, a barrier layer, and a heat-fusible resin layer, which is composed of a laminate including in this order,
An exterior material for an electricity storage device, wherein the barrier layer includes the aluminum alloy foil according to any one of items 1 to 3.
Item 5. Item 5. The temperature difference T ₁ and the temperature difference T ₂ are measured by the following method, and the value obtained by dividing the temperature difference T ₂ by the temperature difference T ₁ is 0.55 or more. Exterior material for power storage devices.
(Measurement of temperature difference T ₁ )
By the differential scanning calorimetry, the temperature difference T ₁ between the extrapolation melting start temperature and the extrapolation melting end temperature of the melting peak temperature of the heat-fusible resin layer is measured.
(Measurement of temperature difference T ₂ )
In the environment of a temperature of 85 ° C., the heat-fusible resin layer is a solution in which the concentration of lithium hexafluorophosphate is 1 mol / l and the volume ratio of ethylene carbonate, diethyl carbonate and dimethyl carbonate is 1: 1: 1. After being left to stand in the electrolytic solution for 72 hours, it is dried. The temperature difference T ₂ between the extrapolation melting start temperature and the extrapolation melting end temperature of the melting peak temperature of the heat-fusible resin layer after drying is measured by differential scanning calorimetry.
Item 6. Between the aluminum alloy foil and the heat-fusible resin layer, an adhesive layer is provided,
Item 6. The exterior material for an electricity storage device according to

Item

4 or 5, wherein the adhesive layer has a logarithmic decrement ΔE at 120 ° C of 0.50 or less in a rigid pendulum measurement.
Item 7. An electricity storage device, wherein an electricity storage device element including at least a positive electrode, a negative electrode, and an electrolyte is housed in a package formed of the outer casing material for an electricity storage device according to any one of Items 4 to 6.
Item 8. At least, a step of obtaining a laminate by laminating the base material layer, the barrier layer, and the heat-fusible resin layer in this order,
Item 4. A method of manufacturing an exterior material for an electricity storage device, which uses the aluminum alloy foil according to any one of Items 1 to 3 as the barrier layer.

DESCRIPTION OF SYMBOLS 1 Base material layer 2 Adhesive layer 3 Barrier layer 4 Heat-fusible resin layer 5 Adhesive layer 6 Surface coating layer 10 Exterior material for power storage devices

Claims

An aluminum alloy foil having a Mg content of 0.20 mass% or more and 5.50 mass% or less for use as an exterior material for an electricity storage device.
The Si content is 0.40 mass% or less, the Fe content is 0.70 mass% or less, the Cu content is 0.20 mass% or less, the Mn content is 1.00 mass% or less, and the Cr content is 0. 50 mass% or less, Zn content is 0.25 mass% or less, other unavoidable impurities are individually 0.05 mass% or less and 0.15 mass% or less in total, and the balance is Al, The aluminum alloy foil according to claim 1.
The aluminum alloy foil according to claim 1 or 2, which has a thickness of 200 μm or less.
At least, a base layer, a barrier layer, and a heat-fusible resin layer, which is composed of a laminate including in this order,
An exterior material for an electricity storage device, wherein the barrier layer contains the aluminum alloy foil according to any one of claims 1 to 3.
The temperature difference T 1 and the temperature difference T 2 are measured by the following method, and the value obtained by dividing the temperature difference T 2 by the temperature difference T 1 is 0.55 or more. Exterior material for power storage devices.
(Measurement of temperature difference T 1 )
By the differential scanning calorimetry, the temperature difference T 1 between the extrapolation melting start temperature and the extrapolation melting end temperature of the melting peak temperature of the heat-fusible resin layer is measured.
(Measurement of temperature difference T 2 )
In the environment of a temperature of 85 ° C., the heat-fusible resin layer is a solution in which the concentration of lithium hexafluorophosphate is 1 mol / l and the volume ratio of ethylene carbonate, diethyl carbonate and dimethyl carbonate is 1: 1: 1. After being left to stand in the electrolytic solution for 72 hours, it is dried. The temperature difference T 2 between the extrapolation melting start temperature and the extrapolation melting end temperature of the melting peak temperature of the heat-fusible resin layer after drying is measured by differential scanning calorimetry.
Between the aluminum alloy foil and the heat-fusible resin layer, an adhesive layer is provided,
The exterior material for an electricity storage device according to claim 4, wherein the adhesive layer has a logarithmic decrement ΔE at 120 ° C. in a rigid body pendulum measurement of 0.50 or less.
An electricity storage device in which an electricity storage device element including at least a positive electrode, a negative electrode, and an electrolyte is housed in a package formed of the outer casing material for an electricity storage device according to any one of claims 4 to 6.
At least, a step of obtaining a laminate by laminating the base material layer, the barrier layer, and the heat-fusible resin layer in this order,
A method of manufacturing an exterior material for an electricity storage device, wherein the aluminum alloy foil according to any one of claims 1 to 3 is used as the barrier layer.