Separation film for electric power storage device and method for manufacturing same, and electric power storage device and method for manufacturing same

Abstract

A separation film for an electric power storage device is used for separating, inside an electric power storage device, a plurality of battery cells that are included in the electric power storage device. The electric power storage device includes at least an exterior material, the plurality of battery cells encapsulated by the exterior material, and the separation film that is provided so as to separate the plurality of battery cells. The plurality of battery cells are electrically connected in series, and the separation film includes an ion barrier layer.

Description

Separation film for power storage device and method for producing same, power storage device and method for producing same

[0001] The present disclosure relates to a separator film for an electricity storage device and a method for producing the same, and to an electricity storage device and a method for producing the same.

[0002] Various types of electricity storage devices have been developed to date, and in all of these devices, packaging materials for electricity storage devices are essential components for sealing electricity storage device elements such as electrodes and electrolytes.

[0003] For example, in metal can batteries, which are used in a wide range of fields, the battery element is sealed in a metallic exterior material (metal can).

[0004] Furthermore, in recent years, laminate sheets in which a base material layer / an adhesive layer / a barrier layer / a heat-sealable resin layer are laminated in this order have also been proposed as packaging materials for electricity storage devices that can be easily processed into a variety of shapes and can achieve thin and lightweight designs. When such a film-like packaging material for electricity storage devices is used, the heat-sealable resin layers positioned in the innermost layers of the packaging material for electricity storage devices are placed opposite each other, and the peripheral edge of the packaging material for electricity storage devices is heat-sealed, thereby sealing the electricity storage device elements with the packaging material for electricity storage devices.

[0005] Japanese Patent Application Laid-Open No. 2008-287971

[0006] For example, high capacity and high voltage are required for power storage devices (e.g., 3C lithium batteries) designed for use in portable consumer electronics, communication devices, and computing devices such as smartphones, tablets, laptops, digital cameras, and portable game consoles.

[0007] The inventors of the present disclosure have investigated increasing the voltage of an electricity storage device by preparing a plurality of electricity storage devices and connecting them in series. However, in such a configuration, because each electricity storage device has a structure in which the battery cell is sealed in an exterior material (e.g., Patent Document 1), the proportion of the volume of the exterior material in the entire plurality of electricity storage devices becomes large, and they have faced the problem that it is not possible to efficiently increase the overall capacity.

[0008] Under these circumstances, a primary object of the present disclosure is to provide a separator film for an electricity storage device that can realize a high-capacity, high-voltage electricity storage device by applying it to an electricity storage device. Another object of the present disclosure is to provide a method for manufacturing the separator film, an electricity storage device using the separator film, and a method for manufacturing the same.

[0009] The inventors of the present disclosure conducted extensive research to solve the above-mentioned problems. As a result, they found that a high-capacity, high-voltage electricity storage device can be realized by configuring an electricity storage device including at least an exterior material, a plurality of battery cells sealed by the exterior material, and a separator film arranged to separate the plurality of battery cells, the plurality of battery cells being electrically connected in series, and the separator film including an ion barrier layer (i.e., a configuration that prevents the plurality of cells sealed in the electricity storage device from being electrically connected via their electrolyte). The present disclosure was completed through further research based on this finding.

[0010] That is, the present disclosure provides the following aspects of the invention: A separator film for an electricity storage device used to separate multiple battery cells included in the electricity storage device within the electricity storage device, the electricity storage device including at least an exterior material, the multiple battery cells sealed with the exterior material, and the separator film arranged to separate the multiple battery cells, the multiple battery cells being electrically connected in series, and the separator film including an ion barrier layer.

[0011] According to the present disclosure, it is possible to provide a separator film for an electricity storage device that can realize a high-capacity, high-voltage electricity storage device by applying it to an electricity storage device. Furthermore, according to the present disclosure, it is possible to provide a method for manufacturing the separator film, an electricity storage device using the separator film, and a method for manufacturing the same.

[0012] 9 is a schematic plan view of an electricity storage device according to the present disclosure. FIG. 1 is a schematic cross-sectional view taken along line A-A' in FIG. 1. FIG. 2 is a schematic cross-sectional view of an electricity storage device according to the present disclosure. FIG. 3 is a schematic cross-sectional view of a separator film for an electricity storage device according to the present disclosure. FIG. 4 is a schematic cross-sectional view of a separator film for an electricity storage device according to the present disclosure. FIG. 5 is a schematic cross-sectional view of a separator film for an electricity storage device according to the present disclosure. FIG. 6 is a schematic cross-sectional view of an exterior material for an electricity storage device according to the present disclosure. FIG. 7 is a schematic plan view of an electricity storage device according to the present disclosure. FIG. 8 is a schematic cross-sectional view taken along line A-A' in FIG. 9. FIG. 9 is a schematic cross-sectional view taken along line B-B' in FIG. 9.

[0013] The separator film for an electricity storage device of the present disclosure is a separator film used to separate multiple battery cells included in the electricity storage device within the electricity storage device. The electricity storage device includes at least an exterior material, multiple battery cells sealed by the exterior material, and a separator film arranged to separate the multiple battery cells. The multiple battery cells are electrically connected in series. The separator film includes an ion barrier layer. By applying the separator film for an electricity storage device of the present disclosure having the above configuration to an electricity storage device, a high-capacity, high-voltage electricity storage device can be realized.

[0014] Hereinafter, with reference to the drawings, a separator film for an electricity storage device according to the present disclosure, a method for producing the separator film, an electricity storage device using the separator film, and a method for producing the same will be described in detail.

[0015] In this specification, when referring to a numerical range, a numerical range indicated with "to" means "greater than or equal to" or "less than or equal to." For example, the notation 2 to 15 mm means 2 mm or greater and 15 mm or less. In the numerical ranges described in stages in this disclosure, the upper or lower limit value described in a certain numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. Furthermore, separately described upper and lower limits, upper and lower limits, or lower and lower limits may each be combined to form a numerical range. Furthermore, in the numerical ranges described in this disclosure, the upper or lower limit value described in a certain numerical range may be replaced with a value shown in the examples.

[0016] Furthermore, methods for confirming the MD of a separator film for an electricity storage device that can be used include XRD, Raman spectroscopy, polarized IR, etc. Furthermore, when the separator film for an electricity storage device is made of a resin, for example, the separator film for an electricity storage device can be left in an environment of 200°C for 2 minutes, and the thermal shrinkage rate after that can be measured, and the larger shrinkage rate can be determined as the MD.

[0017] 1 to 3 and 9 to 11 , a separator film 1 for an electricity storage device according to the present disclosure (hereinafter, sometimes referred to as "separator film 1") is used to separate multiple battery cells included in an electricity storage device 10 within the electricity storage device 10. The electricity storage device 10 includes at least an exterior packaging material 30 for an electricity storage device (hereinafter, sometimes referred to as "exterior packaging material 30"), multiple battery cells sealed by the exterior packaging material 30, and a separator film 1 arranged so as to separate the multiple battery cells.

[0018] In the electricity storage device 10 of the present disclosure, the multiple battery cells are two battery cells 21, 22 in Figures 2 and 9 to 11, and three battery cells 21, 22, 23 in Figure 3. There are no particular restrictions on the number of battery cells included in the electricity storage device 10 of the present disclosure, but from the viewpoint of suitably separating the multiple battery cells with the separator film 1 of the present disclosure, the number is preferably about 2 to 5, and more preferably 2 to 3.

[0019] The separator film 1 of the present disclosure is arranged inside the exterior material 30 of the electricity storage device 10 so as to separate multiple battery cells into individual battery cells. Each battery cell contains an electrode and an electrolyte, and without the separator film 1 of the present disclosure arranged, the individual battery cells would be electrically connected through the electrolyte within the electricity storage device 10, preventing the achievement of high voltages by connecting multiple battery cells in series outside the exterior material. The separator film 1 of the present disclosure includes an ion barrier layer 11, and therefore prevents the multiple cells sealed within the electricity storage device from being electrically connected through the electrolyte.

[0020] For example, in the electricity storage device 10 shown in Figures 1 and 2, a plurality of battery cells, battery cells 21 and 22, are separated by a separator film 1. In Figures 1 and 2, the exterior material 30 is composed of two members, a first exterior material 30a and a second exterior material 30b, and the first exterior material 30a and the second exterior material 30b are sealed at the peripheral edge 10a of the electricity storage device 10 with a separator film 1 between them, thereby separating the battery cells 21 and 22. In Figures 1 and 2, the battery cells 21 are sealed by the first exterior material 30a and the separator film 1, and the battery cells 22 are sealed by the second exterior material 30b and the separator film 1.

[0021] 9 to 11 are schematic diagrams assuming that the exterior casing 30 is made of metal (for example, a metal can battery). When the exterior casing is made of metal, the terminals 2a and 2b do not need to be drawn out from the sealed portion of the exterior casing, and the terminals 2a and 2b can be drawn out by penetrating the exterior casing 30. In the electricity storage device 10 shown in FIGS. 9 to 11, the terminals 2b are also electrically connected in series outside the exterior casing 30.

[0022] 1 and 2 , the separator film 1 located between the first exterior material 30a and the second exterior material 30b is bonded (for example, by welding, heat fusion, etc.) to the first exterior material 30a and the second exterior material 30b, thereby sealing the multiple battery cells with the exterior material 30. For example, if the surface of the separator film 1 is made of metal and the exterior material 30 is also made of metal, the separator film 1 and the exterior material 30 can be bonded by metal welding. The same applies to the electricity storage device 10 in FIGS. 9 to 11 . On the other hand, if the surface of the separator film is made of resin, they can be bonded by heat fusion whether the exterior material is made of metal or is a laminate including a heat-sealable resin layer 35 described below.

[0023] 1 and 2, at the positions where the terminals 2a and 2b are present, the first exterior material 30a and the second exterior material 30b are adhered to the terminals 2a and 2b, and the separation film 1 is also adhered to the terminals 2a and 2b. The terminals 2a and 2b are usually made of metal. Therefore, when the exterior material 30 is made of metal, the exterior material 30 and the terminals 2a and 2b can be adhered by metal welding. Furthermore, when the exterior material 30 is made of a laminate including a heat-sealable resin layer 35 described below, the exterior material 30 and the terminals 2a and 2b can be adhered by heat fusion. Furthermore, when the surface of the separation film 1 is made of metal, the separation film 1 and the terminals 2a and 2b can be adhered by metal welding. Furthermore, when the surface of the separation film 1 is made of resin, the separation film 1 and the terminals 2a and 2b can be adhered by heat fusion.

[0024] Further, for example, in the energy storage device 10 shown in Fig. 3, a plurality of battery cells, that is, battery cell 21, battery cell 22, and battery cell 23, are separated by a separator film 1. In Fig. 3, two separator films 1 are used. In this way, in the energy storage device of the present disclosure, by using a plurality of separator films 1, three or more battery cells can be separated within the energy storage device 10. In Fig. 3, the exterior material 30 is composed of two members, a first exterior material 30a and a second exterior material 30b, and the first exterior material 30a and the second exterior material 30b are sealed at the peripheral edge 10a of the energy storage device 10 with the two separator films 1 interposed therebetween, thereby separating the battery cells 21, battery cell 22, and battery cell 23. In Figure 3, battery cell 21 is sealed by a first exterior material 30a and a separation film 1, battery cell 22 is sealed by a separation film 1, and battery cell 23 is sealed by a second exterior material 30b and a separation film 1.

[0025] 3 , the release film 1 located between the first exterior material 30a and the second exterior material 30b is bonded (for example, by welding, heat fusion, etc.) to the first exterior material 30a and the second exterior material 30b, thereby sealing the multiple battery cells with the exterior material 30. For example, if the surface of the release film 1 is made of metal and the exterior material 30 is also made of metal, the release film 1 and the exterior material 30 can be bonded by metal welding. On the other hand, if the surface of the release film is made of resin, the separation film 1 and the exterior material 30 can be bonded by heat fusion, whether the exterior material is made of metal or is a laminate including the heat-sealable resin layer 35 described below.

[0026] 3, the two separation films 1 are also bonded at positions where the separation film 1 is bonded to the exterior material 30. For example, if the surface of the separation film 1 is made of metal, the two separation films 1 can be bonded by metal welding. Also, for example, if the surface of the separation film 1 is made of resin, the two separation films 1 can be bonded by heat fusion.

[0027] In addition, in Figure 3, at the positions where terminals 2a and 2b are present, the first exterior material 30a and the second exterior material 30b are adhered to terminals 2a and 2b, and the separation film 1 is also adhered to terminals 2a and 2b. Terminals 2a and 2b are usually made of metal. Therefore, when the exterior material 30 is made of metal, the exterior material 30 and terminals 2a and 2b can be adhered by metal welding. Furthermore, when the exterior material 30 is made of a laminate including a heat-sealable resin layer 35 described below, the exterior material 30 and terminals 2a and 2b can be adhered by heat fusion. Furthermore, when the surface of the separation film 1 is made of metal, the separation film 1 and terminals 2a and 2b can be adhered by metal welding. Furthermore, when the surface of the separation film 1 is made of resin, the separation film 1 and terminals 2a and 2b can be adhered by heat fusion.

[0028] In addition, in the peripheral portion 10a of the energy storage device 10, an adhesive film (not shown) may be placed in the area where the terminals 2a and 2b are bonded to the exterior material 30 and the separation film 1 in order to enhance the adhesion of the terminals 2a and 2b by thermal fusion.

[0029] In the energy storage device 10 of the present disclosure, the plurality of battery cells are electrically connected in series. For example, in Fig. 2, the battery cells 21 and 22 each include a terminal 2a and a terminal 2b electrically connected to the electrodes of the battery cell. The terminals 2a and 2b are drawn out from the inside (battery cell side) of the exterior material 30 of the energy storage device 10 to the outside. The terminals 2b of the battery cells 21 and 22 are connected in series. In Fig. 2, the positive electrode (+) of the battery cell 21 and the negative electrode (-) of the battery cell 22 are electrically connected outside the exterior material 30, thereby connecting the battery cells 21 and 22 in series.

[0030] 3, terminals 2a and 2b are not drawn, but battery cells 21, 22, and 23 are connected in series outside the exterior material 30. Connecting battery cells in series can increase the voltage of the power storage device 10. For example, in FIG. 3, if the voltage of each of battery cells 21, 22, and 23 is 3.7 V, connecting battery cells 21, 22, and 23 in series can increase the voltage of the entire power storage device 10 to 3.7 V x 3 = 11.1 V.

[0031] 4 to 7, the separator film 1 of the present disclosure includes at least an ion barrier layer 11. This prevents the multiple cells sealed in the electricity storage device 10 from being electrically connected via their electrolytes.

[0032] The material constituting the ion barrier layer 11 is not particularly limited as long as it can form a film and exhibits the property (ion barrier property) of preventing multiple cells from being electrically connected via their electrolytes. The ion barrier layer 11 can be made of metal, resin, or a combination thereof. The ion barrier layer may be a single layer or multiple layers.

[0033] When the ion barrier layer 11 is made of a metal, it can be made of, for example, a metal foil or a vapor-deposited film having ion barrier properties. Examples of vapor-deposited films include metal vapor-deposited films. The vapor-deposited film constituting the ion barrier layer 11 may also be laminated on the surface of a resin layer. Examples of resin layers forming the vapor-deposited film include fluorine-containing resins such as polyvinylidene chloride, polymers based on chlorotrifluoroethylene (CTFE), polymers based on tetrafluoroethylene (TFE), polymers having fluoroalkyl groups, and polymers based on fluoroalkyl units, as well as ethylene-vinyl alcohol copolymers. The ion barrier layer 11 may have multiple layers. The ion barrier layer 11 preferably includes a layer made of a metal material. Specific examples of the metal material constituting the ion barrier layer 11 include aluminum alloys, stainless steel, titanium steel, and steel plates. When used as a metal foil, the ion barrier layer 11 preferably includes at least one of aluminum alloy foil and stainless steel foil.

[0034] In the ion barrier layer 11, the layer made of the aforementioned metal material may contain recycled metal material. Examples of recycled metal material include recycled aluminum alloy, stainless steel, titanium steel, and steel plate. These recycled materials can be obtained by known methods. Recycled aluminum alloy material can be obtained, for example, by the manufacturing method described in International Publication No. 2022 / 092231. The ion barrier layer 11 may be made of recycled material alone, or may be made of a mixture of recycled and virgin materials. Note that recycled metal material refers to metal material that has been made reusable by collecting, isolating, and refining various products used in the market or waste from manufacturing processes. Furthermore, virgin metal material refers to new metal material refined from natural metal resources (raw materials) and is not recycled material.

[0035] The aluminum alloy foil is preferably a soft aluminum alloy foil made of, for example, an annealed aluminum alloy, and is preferably an iron-containing aluminum alloy foil. In the iron-containing aluminum alloy foil (100% by mass), the iron content is preferably 0.1 to 9.0% by mass, and more preferably 0.5 to 2.0% by mass. By setting the iron content to 9.0% by mass or less, an exterior material for an electricity storage device having superior flexibility can be obtained. Examples of the soft aluminum alloy foil include JIS H4160:1994 A1100H-O, JIS H4160:1994 A3003H-O, JIS H4160:1994 A3004H-O, JIS H4160:1994 A5052H-O, JIS H4160:1994 A8021H-O, JIS H4160:1994 A8079H-O, JIS H4000:2014 A1100P-O, JIS H4000:2014 A3003P-O, JIS H4000:2014 A3004P-O, JIS H4000:2014 A8021P-O, and JIS Examples of suitable aluminum alloy foils include those having a composition specified in H4000:2014 A8079P-O. Silicon, magnesium, copper, manganese, etc. may also be added as needed. Softening can be achieved by annealing or other methods.

[0036] Examples of the stainless steel foil include austenitic, ferritic, austenitic-ferritic, martensitic, and precipitation hardened stainless steel foils. The stainless steel foil is preferably made of austenitic stainless steel.

[0037] Specific examples of austenitic stainless steels that form the stainless steel foil include SUS304, SUS301, and SUS316L, with SUS304 being particularly preferred.

[0038] In the case of a metal foil, the thickness of the ion barrier layer 11 should be sufficient to at least form a film and exhibit ion barrier properties, and may be, for example, approximately 9 to 200 μm. The thickness of the ion barrier layer 11 is preferably approximately 85 μm or less, more preferably approximately 50 μm or less, even more preferably approximately 40 μm or less, and particularly preferably approximately 35 μm or less. The thickness of the ion barrier layer 11 is preferably approximately 10 μm or more, even more preferably approximately 20 μm or more, and more preferably approximately 25 μm or more. Preferred ranges for the thickness of the ion barrier layer 11 include approximately 10 to 85 μm, approximately 10 to 50 μm, approximately 10 to 40 μm, approximately 10 to 35 μm, approximately 20 to 85 μm, approximately 20 to 50 μm, approximately 20 to 40 μm, approximately 20 to 35 μm, approximately 25 to 85 μm, approximately 25 to 50 μm, approximately 25 to 40 μm, and approximately 25 to 35 μm. When the ion barrier layer 11 is made of an aluminum alloy foil, the above-mentioned range is particularly preferred. Furthermore, particularly when the ion barrier layer 11 is made of a stainless steel foil, the thickness of the stainless steel foil is preferably about 60 μm or less, more preferably about 50 μm or less, even more preferably about 40 μm or less, even more preferably about 30 μm or less, and particularly preferably about 25 μm or less. The thickness of the stainless steel foil is preferably about 10 μm or more, more preferably about 15 μm or more. Preferred ranges for the thickness of the stainless steel foil include about 10 to 60 μm, about 10 to 50 μm, about 10 to 40 μm, about 10 to 30 μm, about 10 to 25 μm, about 15 to 60 μm, about 15 to 50 μm, about 15 to 40 μm, about 15 to 30 μm, and about 15 to 25 μm.

[0039] Furthermore, when the ion barrier layer 11 is a metal foil, it is also preferable to provide a corrosion-resistant coating on the surface to prevent dissolution and corrosion. In particular, when the ion barrier layer 11 forms the surface of at least one side of the separator film 1, the ion barrier layer 11 is configured to come into contact with the electrolyte of the battery cell, so it is preferable to provide a corrosion-resistant coating on the surface. The ion barrier layer 11 may be provided with a corrosion-resistant coating on both sides.

[0040] Here, the corrosion-resistant coating refers to a thin film that is formed on the surface of the ion barrier layer 11 by, for example, hydrothermal conversion treatment such as boehmite treatment, chemical conversion treatment, anodizing treatment, plating treatment with nickel or chromium, or corrosion prevention treatment such as applying a coating agent, to provide the ion barrier layer 11 with corrosion resistance (e.g., acid resistance, alkali resistance, etc.). Specifically, the corrosion-resistant coating refers to a coating that improves the acid resistance of the ion barrier layer 11 (acid-resistant coating), a coating that improves the alkali resistance of the ion barrier layer 11 (alkali-resistant coating), etc. The corrosion-resistant coating may be formed by one type of treatment or a combination of two or more types. Furthermore, the corrosion-resistant coating may be formed in a single layer or in multiple layers. Furthermore, among these treatments, hydrothermal conversion treatment and anodizing treatment are treatments that dissolve the metal foil surface with a treatment agent to form a metal compound with excellent corrosion resistance. These treatments may also be included in the definition of chemical conversion treatment. Furthermore, when the ion barrier layer 11 is provided with a corrosion-resistant film, the corrosion-resistant film is included in the ion barrier layer 11 .

[0041] Various corrosion-resistant coatings formed by chemical conversion treatments are known, including mainly corrosion-resistant coatings containing at least one of phosphates, chromates, fluorides, triazine thiol compounds, and rare earth oxides. Examples of chemical conversion treatments using phosphates and chromates include chromate chromate treatment, phosphate chromate treatment, phosphate-chromate treatment, and chromate treatment. Examples of chromium compounds used in these treatments include chromium nitrate, chromium fluoride, chromium sulfate, chromium acetate, chromium oxalate, chromium biphosphate, chromate acetylacetate, chromium chloride, and potassium chromium sulfate. Examples of phosphorus compounds used in these treatments include sodium phosphate, potassium phosphate, ammonium phosphate, and polyphosphoric acid. Examples of chromate treatments include etching chromate treatment, electrolytic chromate treatment, and paint-on chromate treatment, with paint-on chromate treatment being preferred. This paint-type chromate treatment involves first degreasing at least the inner surface of an ion barrier layer (e.g., an aluminum alloy foil) using a well-known method such as alkali immersion, electrolytic cleaning, acid pickling, electrolytic pickling, or acid activation, and then coating the degreased surface with a treatment solution containing, as its main component, a metal phosphate such as chromium (Cr) phosphate, titanium (Ti) phosphate, zirconium (Zr) phosphate, or zinc (Zn) phosphate, or a mixture of these metal salts, or a treatment solution containing, as its main component, a nonmetallic phosphate and a mixture of these nonmetallic salts, or a mixture of these with a synthetic resin, by a well-known coating method such as roll coating, gravure printing, or immersion, followed by drying. The treatment solution can be, for example, water, alcoholic solvents, hydrocarbon solvents, ketone solvents, ester solvents, or ether solvents, with water being preferred. Examples of the resin component used here include polymers such as phenolic resins and acrylic resins, and chromate treatment using an aminated phenol polymer having repeating units represented by the following general formulas (1) to (4). The aminated phenol polymer may contain one type of repeating unit represented by the following general formulas (1) to (4) alone, or two or more types of repeating units may be contained in any combination.The acrylic resin is preferably polyacrylic acid, an acrylic acid methacrylic acid ester copolymer, an acrylic acid maleic acid copolymer, an acrylic acid styrene copolymer, or a derivative thereof such as a sodium salt, an ammonium salt, or an amine salt. Derivatives of polyacrylic acid, such as an ammonium salt, a sodium salt, or an amine salt of polyacrylic acid, are particularly preferred. In the present disclosure, polyacrylic acid refers to a polymer of acrylic acid. The acrylic resin is also preferably a copolymer of acrylic acid and a dicarboxylic acid or a dicarboxylic acid anhydride, or an ammonium salt, a sodium salt, or an amine salt of a copolymer of acrylic acid and a dicarboxylic acid or a dicarboxylic acid anhydride. Only one type of acrylic resin may be used, or two or more types may be mixed and used.

[0042]

[0043]

[0044]

[0045]

[0046] In the general 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. 1 and R 2 are the same or different and represent a hydroxy group, an alkyl group, or a hydroxyalkyl group. 1 and R 2 Examples of the alkyl group represented by X and R include linear or branched alkyl groups having 1 to 4 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, and tert-butyl. 1 and R 2Examples of the hydroxyalkyl group represented by the formula (1) include a linear or branched alkyl group having 1 to 4 carbon atoms substituted with one hydroxy group, such as a hydroxymethyl group, a 1-hydroxyethyl group, a 2-hydroxyethyl group, a 1-hydroxypropyl group, a 2-hydroxypropyl group, a 3-hydroxypropyl group, a 1-hydroxybutyl group, a 2-hydroxybutyl group, a 3-hydroxybutyl group, and a 4-hydroxybutyl group. 1 and R 2 The alkyl group and hydroxyalkyl group represented by the formula (1) may be the same or different. In the formulae (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 repeating units represented by the formulae (1) to (4) is preferably about 500 to 1,000,000, for example, and more preferably about 1,000 to 20,000. The aminated phenol polymer can be prepared, for example, by polycondensing a phenol compound or a naphthol compound with formaldehyde to produce a polymer comprising repeating units represented by the formula (1) or (3), and then polycondensing the polymer with formaldehyde and an amine (R 1 R 2 NH) to form a functional group (-CHNR 1 R 2 The aminated phenol polymers may be used singly or in combination of two or more.

[0047] Another example of a corrosion-resistant coating is a thin film formed by a coating-type corrosion prevention treatment in which a coating agent containing at least one selected from the group consisting of a rare earth element oxide sol, an anionic polymer, and a cationic polymer is applied. The coating agent may further contain phosphoric acid or a phosphate salt, and a crosslinking agent for crosslinking the polymer. The rare earth element oxide sol contains rare earth element oxide fine particles (e.g., particles with an average particle size of 100 nm or less) dispersed in a liquid dispersion medium. Examples of rare earth element oxides include cerium oxide, yttrium oxide, neodymium oxide, and lanthanum oxide, with cerium oxide being preferred from the perspective of further improving adhesion. The rare earth element oxide contained in the corrosion-resistant coating can be used alone or in combination of two or more. Examples of liquid dispersion media for the rare earth element oxide sol include various solvents such as water, alcohol-based solvents, hydrocarbon-based solvents, ketone-based solvents, ester-based solvents, and ether-based solvents, with water being preferred. Preferred examples of cationic polymers include polyethyleneimine, ionic polymer complexes consisting of polyethyleneimine and a polymer having a carboxylic acid, primary amine-grafted acrylic resins in which a primary amine is graft-polymerized onto an acrylic backbone, polyallylamine or its derivatives, and aminated phenols. Preferred anionic polymers include poly(meth)acrylic acid or its salts, or copolymers primarily composed of (meth)acrylic acid or its salts. The crosslinking agent is preferably at least one selected from the group consisting of a compound having a functional group selected from an isocyanate group, a glycidyl group, a carboxyl group, or an oxazoline group, and a silane coupling agent. The phosphoric acid or phosphoric acid salt is preferably a condensed phosphoric acid or a condensed phosphate salt.

[0048] An example of a corrosion-resistant coating is one formed by applying a solution of phosphoric acid in which fine particles of a metal oxide such as aluminum oxide, titanium oxide, cerium oxide, or tin oxide, or barium sulfate are dispersed to the surface of a metal foil, and then baking the solution at 150°C or higher.

[0049] The corrosion-resistant coating may have a laminated structure, if necessary, by further laminating at least one of a cationic polymer and an anionic polymer, such as those mentioned above.

[0050] The composition of the corrosion-resistant film can be analyzed by, for example, time-of-flight secondary ion mass spectrometry.

[0051] The amount of the corrosion-resistant film formed on the surface of the ion barrier layer 11 in the chemical conversion treatment is not particularly limited. For example, in the case of applying chromate treatment, the amount of the corrosion-resistant film formed on the surface of the ion barrier layer 11 is 2 It is desirable that the chromate compound is contained in an amount, calculated as chromium, of about 0.5 to 50 mg, preferably about 1.0 to 40 mg, the phosphorus compound in an amount, calculated as phosphorus, of about 0.5 to 50 mg, preferably about 1.0 to 40 mg, and the aminated phenol polymer in an amount, calculated as phosphorus, of about 1.0 to 200 mg, preferably about 5.0 to 150 mg, per 1000 ml of the aqueous solution.

[0052] The thickness of the corrosion-resistant coating is not particularly limited, but is preferably about 1 nm to 20 μm, more preferably about 1 nm to 100 nm, and even more preferably about 1 nm to 50 nm, from the viewpoint of the cohesive strength of the coating and the adhesive strength between the ion barrier layer 11 and the adjacent layer. The thickness of the corrosion-resistant coating can be measured by observation with a transmission electron microscope, or by a combination of observation with a transmission electron microscope and energy dispersive X-ray spectroscopy or electron energy loss spectroscopy. Analysis of the composition of the corrosion-resistant coating using time-of-flight secondary ion mass spectrometry can reveal, for example, the presence of secondary ions consisting of Ce, P, and O (e.g., Ce2PO4 + , CePO4 - or at least one of ions of Cr, P, and O (e.g., CrPO2 + , CrPO4 - Peaks derived from at least one of the above are detected.

[0053] The chemical conversion treatment is performed by applying a solution containing a compound used to form the corrosion-resistant coating to the surface of the ion barrier layer by bar coating, roll coating, gravure coating, immersion, or other methods, and then heating the solution so that the ion temperature reaches approximately 70 to 200°C. Furthermore, before applying the chemical conversion treatment to the ion barrier layer, the ion barrier layer may be subjected to a degreasing treatment using an alkali immersion method, electrolytic cleaning, acid cleaning, electrolytic acid cleaning, or other methods. By performing such a degreasing treatment, the chemical conversion treatment of the surface of the ion barrier layer can be performed more efficiently. Furthermore, using an acid degreasing agent prepared by dissolving a fluorine-containing compound in an inorganic acid for the degreasing treatment not only degreases the metal foil but also forms a fluoride of the metal, which is in a passive state. In such cases, only the degreasing treatment may be performed.

[0054] Furthermore, when the ion barrier layer 11 is formed of a resin, the resin is not particularly limited as long as it is a material that can exhibit the property of preventing electrical connection via an electrolyte (ion barrier property). Furthermore, a metal vapor deposition film, an inorganic oxide vapor deposition film, a carbon-containing inorganic oxide vapor deposition film, or the like may or may not be laminated on the surface of the resin layer that constitutes the ion barrier layer 11.

[0055] Examples of resins that form the ion barrier layer 11 include polyester, epoxy resin, fluororesin, polyurethane, silicone resin, phenolic resin, polyolefin resin, polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, and modified versions of these resins. The resin that forms the ion barrier layer 11 may also be a copolymer of these resins, a modified version of the copolymer, or a mixture of these resins.

[0056] Of these, polyester is preferred as the resin for forming the ion barrier layer 11 .

[0057] The ion barrier layer 11 preferably contains these resins as a main component, and more preferably contains polyester as a main component. Here, the term "main component" means that the content of the resin component contained in the ion barrier layer 11 is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 99% by mass or more.

[0058] Specific examples of polyesters include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolymer polyesters. Copolymer polyesters include copolymer polyesters containing ethylene terephthalate as the main repeating unit. Specific examples include copolymer polyesters in which ethylene terephthalate as the main repeating unit is polymerized with ethylene isophthalate (hereinafter abbreviated as polyethylene (terephthalate / isophthalate)), polyethylene (terephthalate / adipate), polyethylene (terephthalate / sodium sulfoisophthalate), polyethylene (terephthalate / sodium isophthalate), polyethylene (terephthalate / phenyl-dicarboxylate), and polyethylene (terephthalate / decanedicarboxylate). Furthermore, the polyester may be a copolymer of two or more polyesters selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, and polyethylene isophthalate. These polyesters may be used alone or in combination as a mixture of two or more.

[0059] The thickness of the ion barrier layer 11 is not particularly limited as long as the effects of the present invention are achieved, and is, for example, about 10 μm or more, preferably about 15 μm or more, more preferably about 20 μm or more, and even more preferably about 25 μm or more, and is preferably about 200 μm or less, more preferably about 150 μm or less, and even more preferably about 100 μm or less. Preferred ranges include about 10 to 200 μm, about 10 to 150 μm, about 10 to 100 μm, about 15 to 200 μm, about 15 to 150 μm, about 15 to 100 μm, about 20 to 200 μm, about 20 to 150 μm, about 20 to 100 μm, about 25 to 200 μm, about 25 to 150 μm, and about 25 to 100 μm. In addition, as shown in FIG. 1, when the separation film 1 of the present disclosure is composed only of an ion barrier layer 11, it is also preferable that the thickness of the ion barrier layer 11 be the thickness of the separation film 1 of the present disclosure described later.

[0060] (Other Layers) The separation film 1 may further include other layers, if necessary, in addition to the ion barrier layer 11. When the separation film 1 includes other layers in addition to the ion barrier layer 11, the separation film 1 is composed of a laminate film including the ion barrier layer 11 and the other layers.

[0061] In the separator film 1, a resin layer is preferably used as the other layer. When the separator film 1 includes another layer, the other layer is laminated on at least one side of the ion barrier layer 11.

[0062] <Resin layers 12, 13> When the separation film 1 of the present disclosure is formed from a laminate film, the laminate structure may be, for example, a two-layer structure in which the resin layer 12 and the ion barrier layer 11 are laminated in this order as shown in Fig. 5, a three-layer structure in which the resin layer 12, the ion barrier layer 11, and the resin layer 13 are laminated in this order as shown in Fig. 6, a three-layer structure (not shown) in which an adhesive layer is laminated between the resin layer 12 and the ion barrier layer 11 in the laminate structure shown in Fig. 5, or a five-layer structure in which adhesive layers 14 and 15 are laminated between the resin layer 12 and the ion barrier layer 11 and between the resin layer 13 and the ion barrier layer 11, respectively, as shown in Fig. 7. Furthermore, a protective layer or the like may be provided on the side of the resin layer 12 and the resin layer 13 opposite the ion barrier layer 11 side, or a lubricant may be attached thereto.

[0063] When the separation film 1 of the present disclosure further comprises a resin layer in addition to the ion barrier layer 11, the resin forming the resin layer is preferably a resin that exhibits heat fusion properties such as a thermoplastic resin, and for example, a resin containing a polyolefin skeleton such as polyolefin or acid-modified polyolefin is preferred. For example, when the separation film 1 of the present disclosure is subjected to deep drawing, stretch molding, or the like, it is preferable to further comprise a resin layer in addition to the ion barrier layer 11. The inclusion of a polyolefin skeleton in the resin constituting the resin layer can be analyzed, for example, by infrared spectroscopy, gas chromatography mass spectrometry, or the like. Furthermore, when the resin constituting the resin layer is analyzed by infrared spectroscopy, a peak derived from maleic anhydride is preferably detected. For example, when maleic anhydride-modified polyolefin is measured by infrared spectroscopy, a peak at a wavenumber of 1760 cm -1 Nearby and wave number 1780 cm -1 A peak derived from maleic anhydride is detected around . When the resin layer is made of 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 becomes small and may not be detected. In such cases, analysis can be performed by nuclear magnetic resonance spectroscopy.

[0064] The resin layer preferably contains a resin containing a polyolefin skeleton as a main component, more preferably a polyolefin as a main component, and even more preferably polypropylene as a main component. Here, the term "main component" refers to a resin component contained in the resin layer whose content is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 99% by mass or more. For example, when the resin layer contains polypropylene as a main component, the content of polypropylene in the resin component contained in the resin layer is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 99% by mass or more.

[0065] Specific examples of polyolefins include polyethylenes such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; ethylene-α-olefin copolymers; polypropylenes such as homopolypropylene, block copolymers of polypropylene (e.g., block copolymers of propylene and ethylene), and random copolymers of polypropylene (e.g., random copolymers of propylene and ethylene); propylene-α-olefin copolymers; and ethylene-butene-propylene terpolymers. Among 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.

[0066] The polyolefin may also be a cyclic polyolefin. Cyclic polyolefins are copolymers of olefins and cyclic monomers, and examples of olefins constituting the cyclic polyolefins include ethylene, propylene, 4-methyl-1-pentene, styrene, butadiene, and isoprene. Examples of cyclic monomers constituting the cyclic polyolefins include cyclic alkenes such as norbornene; and cyclic dienes such as cyclopentadiene, dicyclopentadiene, cyclohexadiene, and norbornadiene. Among these, cyclic alkenes are preferred, and norbornene is more preferred.

[0067] The polyolefin may be an acid-modified polyolefin. Since acid-modified polyolefins have excellent adhesion to metals, when the separation film 1 of the present disclosure is directly adhered to a metal, such as the exterior material 30 made of metal or the terminals 2a and 2b made of metal, the resin layer preferably contains an acid-modified polyolefin.

[0068] Acid-modified polyolefins are polymers modified by block polymerization or graft polymerization of polyolefins with an acid component. Examples of acid-modified polyolefins include the above-mentioned polyolefins, copolymers of the above-mentioned polyolefins with polar molecules such as acrylic acid or methacrylic acid, and crosslinked polyolefins. Examples of acid components used for acid modification include carboxylic acids or anhydrides thereof, such as maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, and itaconic anhydride.

[0069] The acid-modified polyolefin may be an acid-modified cyclic polyolefin. The acid-modified cyclic polyolefin is a polymer obtained by copolymerizing a part of the monomers constituting the cyclic polyolefin by replacing it with an acid component, or by block polymerizing or graft polymerizing an acid component onto the cyclic polyolefin. 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.

[0070] Preferred acid-modified polyolefins include polyolefins modified with carboxylic acid or its anhydride, polypropylenes modified with carboxylic acid or its anhydride, maleic anhydride-modified polyolefins, and maleic anhydride-modified polypropylenes.

[0071] The resin layer may be formed of one type of resin alone or a blend polymer of two or more types of resins.Furthermore, the resin layer may be formed of only one layer, or may be formed of two or more layers of the same or different resins.

[0072] When a resin layer such as the resin layers 12 and 13 is bonded to the ion barrier layer 11 via the adhesive layers 14 and 15, a preformed resin film may be used as the resin layer. Alternatively, the resin forming the resin layer may be formed into a film on the surface of the ion barrier layer 11 or the adhesive layers 14 and 15 by extrusion molding, coating, or the like, to form a resin layer formed from the resin film.

[0073] In the separation film 1 of the present disclosure, the resin layer preferably constitutes the surface of the separation film 1 .

[0074] The resin layer may also contain a lubricant, etc., as necessary. When the resin layer contains a lubricant, the slipperiness of the separation film 1 can be increased, and the handleability of the separation film 1 is improved during the manufacturing process of the electricity storage device 10. The lubricant is preferably present on at least one of the surface and the interior of the resin layer.

[0075] The lubricant is not particularly limited, and known lubricants can be used. As the lubricant, an amide-based lubricant is preferably used. The lubricant may be used alone or in combination of two or more types, and a combination of two or more types is preferred.

[0076] Specific examples of amide-based lubricants include saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, methylolamides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, fatty acid ester amides, and aromatic bisamides. Specific examples of saturated fatty acid amides 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 substituted amides include N-oleyl palmitic 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 methylolamides include methylol stearic acid amide. Specific examples of saturated fatty acid bisamides include methylene bisstearic acid amide, ethylene biscapric acid amide, ethylene bislauric acid amide, ethylene bisstearic acid amide, ethylene bishydroxystearic acid amide, ethylene bisbehenic acid amide, hexamethylene bisstearic acid amide, hexamethylene bisbehenic acid amide, hexamethylene hydroxystearic acid amide, N,N'-distearyl adipamide, N,N'-distearyl sebacic acid amide, etc. Specific examples of unsaturated fatty acid bisamides include ethylene bisoleic acid amide, ethylene biserucic acid amide, hexamethylene bisoleic acid amide, N,N'-dioleyl adipamide, N,N'-dioleyl sebacic acid amide, etc. Specific examples of fatty acid ester amides include stearamidoethyl stearate, etc. Specific examples of aromatic bisamides include m-xylylene bisstearic acid amide, m-xylylene bishydroxystearic acid amide, N,N'-distearyl isophthalic acid amide, etc. The lubricant may be used alone or in combination of two or more types, and a combination of two or more types is preferred.

[0077] When a lubricant is present on the surface of the resin layer, the amount of the lubricant is not particularly limited, but is preferably about 1 mg / m 2or more, more preferably about 3 mg / m 2 or more, more preferably about 5 mg / m 2 or more, more preferably about 10 mg / m 2 or more, more preferably about 15 mg / m 2 or more, and preferably about 50 mg / m 2 or less, more preferably about 40 mg / m 2 The preferred range is 1 to 50 mg / m 2 Degree, 1-40mg / m 2 Degree, 3-50mg / m 2 Degree, 3-40mg / m 2 degree, 5-50mg / m 2 degree, 5-40mg / m 2 degree, 10-50mg / m 2 degree, 10-40mg / m 2 degree, 15-50mg / m 2 degree, 15-40mg / m 2 The degree of

[0078] When a lubricant is present inside the resin layer, the amount thereof is not particularly limited, but is preferably about 100 ppm or more, more preferably about 300 ppm or more, and even more preferably about 500 ppm or more, and is preferably about 3000 ppm or less, more preferably about 2000 ppm or less, and preferred ranges include about 100 to 3000 ppm, about 100 to 2000 ppm, about 300 to 3000 ppm, about 300 to 2000 ppm, about 500 to 3000 ppm, and about 500 to 2000 ppm. When two or more types of lubricant are present inside the resin layer, the above amount of lubricant is the total amount of lubricant. Furthermore, when two or more types of lubricants are present inside the resin layer, the amount of the first type of lubricant is not particularly limited, but is preferably about 100 ppm or more, more preferably about 300 ppm or more, and even more preferably about 500 ppm or more, and is preferably about 3000 ppm or less, more preferably about 2000 ppm or less, and preferred ranges include about 100 to 3000 ppm, about 100 to 2000 ppm, about 300 to 3000 ppm, about 300 to 2000 ppm, about 500 to 3000 ppm, and about 500 to 2000 ppm. The amount of the second type of lubricant present is not particularly limited, but is preferably about 50 ppm or more, more preferably about 100 ppm or more, and even more preferably about 200 ppm or more, and is preferably about 1500 ppm or less, more preferably about 1000 ppm or less, and preferred ranges include about 50 to 1500 ppm, about 50 to 1000 ppm, about 100 to 1500 ppm, about 100 to 1000 ppm, about 200 to 1500 ppm, and about 200 to 1000 ppm.

[0079] The lubricant present on the surface of the resin layer may be a lubricant exuded from the resin constituting the resin layer, or a lubricant applied to the surface of the resin layer.

[0080] The resin layer may also contain a pigment, if necessary. Various inorganic pigments can be used as the pigment. A specific example of a pigment is carbon (carbon, graphite). Carbon (carbon, graphite) is a material commonly used inside electricity storage devices and is unlikely to leach into the electrolyte. Furthermore, the coloring effect is significant, and a sufficient coloring effect can be obtained with an amount added that does not impair adhesion. Furthermore, the coloring effect is not severe, and the apparent melt viscosity of the added resin can be increased without melting due to heat. Furthermore, the pressurized portion can be prevented from becoming thin during thermal bonding (heat sealing), thereby providing excellent sealing between the exterior material 30 and the separation film 1, for example.

[0081] When a pigment is added to the resin layer, for example, when carbon black having a particle size of about 0.03 μm is used, the amount of the pigment added is about 0.05 to 0.3 parts by mass, and preferably about 0.1 to 0.2 parts by mass, per 100 parts by mass of the resin component forming the resin layer. By adding a pigment to the resin layer, the presence or absence of the separator film 1 for an electricity storage device can be detected by a sensor or visually inspected.

[0082] Further, in the separation film 1, the thickness of the resin layer is not particularly limited, but from the viewpoint of exhibiting good heat fusion properties, it is preferably about 15 μm or more, more preferably about 18 μm or more, more preferably about 20 μm or more, and also, for example, about 100 μm or less, preferably about 85 μm or less, more preferably about 80 μm or less, and preferred ranges include about 15 to 100 μm, about 15 to 85 μm, about 15 to 80 μm, about 18 to 100 μm, about 18 to 85 μm, about 18 to 80 μm, about 20 to 100 μm, about 20 to 85 μm, and about 20 to 80 μm. For example, when the thickness of the adhesive layer described below is 10 μm or more, the thickness of the resin layer is preferably about 85 μm or less, more preferably about 15 to 45 μm. For example, when the thickness of the adhesive layer described below is less than 10 μm or when no adhesive layer is provided, the thickness of the resin layer is preferably about 20 μm or more, more preferably about 35 to 85 μm.

[0083] <Adhesive Layer> As described above, when the separation film 1 of the present disclosure includes a resin layer, an adhesive layer can be provided, if necessary, between the resin layer and the ion barrier layer 11 for the purpose of increasing the adhesion therebetween. Figure 7 illustrates a configuration in which the resin layer 12 and the ion barrier layer 11 are laminated with an adhesive layer 14 interposed therebetween, and the resin layer 13 and the ion barrier layer 11 are laminated with an adhesive layer 15 interposed therebetween.

[0084] The adhesive layer is formed of a resin capable of bonding the ion barrier layer 11 and the resin layer. Examples of resins used to form the adhesive layer include resins used as adhesives. Such adhesives may be any of chemical reaction type, solvent volatilization type, hot melt type, and thermocompression type. In addition, the adhesive may be a two-component curing adhesive (two-component adhesive), a one-component curing adhesive (one-component adhesive), or a resin that does not involve a curing reaction. In addition, the adhesive layer may be a single layer or a multilayer.

[0085] Specific examples of adhesive components contained in the adhesive include polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolymer polyesters; polyethers; polyurethanes; epoxy resins; phenolic resins; polyamides such as nylon 6, nylon 66, nylon 12, and copolymer polyamides; polyolefin-based resins such as polyolefins, cyclic polyolefins, acid-modified polyolefins, and acid-modified cyclic polyolefins; polyvinyl acetate; cellulose; (meth)acrylic resins; polyimides; polycarbonates; amino resins such as urea resins and melamine resins; rubbers such as chloroprene rubber, nitrile rubber, and styrene-butadiene rubber; and silicone resins. These adhesive components may be used alone or in combination with two or more. Among these adhesive components, polyurethane adhesives are preferred. Furthermore, the adhesive strength of these adhesive component resins can be increased by using an appropriate curing agent in combination. The curing agent is selected appropriately from polyisocyanates, multifunctional epoxy resins, oxazoline group-containing polymers, polyamine resins, acid anhydrides, and the like, depending on the functional groups possessed by the adhesive components.

[0086] Examples of polyurethane adhesives include polyurethane adhesives containing a first part containing a polyol compound and a second part containing an isocyanate compound. Two-component curing polyurethane adhesives are preferred, with a polyol such as polyester polyol, polyether polyol, or acrylic polyol as the first part and an aromatic or aliphatic polyisocyanate as the second part. Examples of polyurethane adhesives include polyurethane adhesives containing a polyurethane compound obtained by reacting a polyol compound with an isocyanate compound in advance, and an isocyanate compound. Examples of polyurethane adhesives include polyurethane adhesives containing a polyurethane compound obtained by reacting a polyol compound with an isocyanate compound in advance, and a polyol compound. Examples of polyurethane adhesives include polyurethane adhesives obtained by reacting a polyurethane compound obtained by reacting a polyol compound with an isocyanate compound in advance with moisture, such as in the air, and then curing the polyurethane compound. Polyester polyols having hydroxyl groups on the side chains in addition to terminal hydroxyl groups in the repeating unit are preferably used as the polyol compound. Examples of the second part include aliphatic, alicyclic, aromatic, and araliphatic isocyanate compounds. Examples of isocyanate compounds include hexamethylene diisocyanate (HDI), xylylene diisocyanate (XDI), isophorone diisocyanate (IPDI), hydrogenated XDI (H6XDI), hydrogenated MDI (H12MDI), tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), and naphthalene diisocyanate (NDI). Examples of polyisocyanate compounds include polyfunctional isocyanate-modified compounds of one or more of these diisocyanates. Multimers (e.g., trimers) can also be used as polyisocyanate compounds. Examples of such multimers include adducts, biurets, and nurates. Forming the adhesive layer using a polyurethane adhesive provides the electrical storage device exterior material with excellent electrolyte resistance, and even if the electrolyte adheres to the end surface of the separation film 1, peeling between the ion barrier layer 11 and the resin layer is suppressed.

[0087] Furthermore, from the viewpoint of firmly adhering the adhesive layer and the resin layer, the resin used to form the adhesive layer preferably contains a polyolefin skeleton, and examples thereof include the polyolefins, acid-modified polyolefins, cyclic polyolefins, and acid-modified cyclic polyolefins exemplified for the resin layer described above. On the other hand, from the viewpoint of firmly adhering the ion barrier layer 11 and the adhesive layer, the adhesive layer preferably contains an acid-modified polyolefin. Examples of acid-modified components include dicarboxylic acids such as maleic acid, itaconic acid, succinic acid, and adipic acid, as well as their anhydrides, acrylic acid, and methacrylic acid. However, maleic anhydride is most preferred in terms of ease of modification and versatility. Furthermore, from the viewpoint of the heat resistance of the separation film 1, the olefin component is preferably a polypropylene-based resin, and the adhesive layer most preferably contains maleic anhydride-modified polypropylene.

[0088] When the resin used to form the adhesive layer contains a polyolefin skeleton, the adhesive layer preferably contains a resin containing a polyolefin skeleton as the main component, more preferably an acid-modified polyolefin as the main component, and even more preferably an acid-modified polypropylene as the main component. Here, the term "main component" refers to a resin component whose content is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 99% by mass or more of the resin component contained in the adhesive layer. For example, when the adhesive layer contains acid-modified polypropylene as the main component, the content of acid-modified polypropylene in the resin component contained in the adhesive layer is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 99% by mass or more.

[0089] The inclusion of a polyolefin skeleton in the resin constituting the adhesive layer can be determined by, for example, infrared spectroscopy, gas chromatography mass spectrometry, or the like, and the analysis method is not particularly limited. Furthermore, the inclusion of an acid-modified polyolefin in the resin constituting the adhesive layer can be determined by, for example, measuring a maleic anhydride-modified polyolefin by infrared spectroscopy, and finding a wave number of 1760 cm -1 Nearby and wave number 1780 cm -1 A peak derived from maleic anhydride is detected around this point. However, if the degree of acid modification is low, the peak may be small and not be detected. In this case, analysis can be performed using nuclear magnetic resonance spectroscopy.

[0090] Furthermore, from the viewpoint of durability such as heat resistance and content resistance of the separation film 1 and from the viewpoint of reducing the thickness, it is more preferable that the adhesive layer is a cured product of a resin composition containing an acid-modified polyolefin and a curing agent. Preferred examples of the acid-modified polyolefin include those mentioned above.

[0091] The adhesive layer is preferably 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. 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 and a compound having an epoxy group is particularly preferred. The adhesive layer preferably contains at least one selected from the group consisting of polyurethane, polyester, and epoxy resin, more preferably polyurethane and epoxy resin. Examples of polyesters include ester resins formed by the reaction of epoxy groups with maleic anhydride groups, and amide ester resins formed by the reaction of oxazoline groups with maleic anhydride groups. If unreacted curing agents such as compounds having an isocyanate group, compounds having an oxazoline group, or epoxy resins remain in the adhesive layer, the presence of the unreacted materials can be confirmed by a method selected from, for example, infrared spectroscopy, Raman spectroscopy, time-of-flight secondary ion mass spectrometry (TOF-SIMS), and the like.

[0092] Furthermore, from the viewpoint of further enhancing the adhesion between the ion barrier layer 11 and the adhesive layer, the adhesive layer is preferably a cured product of a resin composition containing a curing agent having at least one selected from the group consisting of an oxygen atom, a heterocycle, a C═N bond, and a C—O—C bond. Examples of curing agents having a heterocycle include curing agents having an oxazoline group and curing agents having an epoxy group. Examples of curing agents having a C═N bond include curing agents having an oxazoline group and curing agents having an isocyanate group. Examples of curing agents having a C—O—C bond include curing agents having an oxazoline group and curing agents having an epoxy group. Whether the adhesive layer is a cured product of a resin composition containing such a curing agent can be confirmed by, for example, gas chromatography mass spectrometry (GCMS), infrared spectroscopy (IR), time-of-flight secondary ion mass spectrometry (TOF-SIMS), X-ray photoelectron spectroscopy (XPS), or other methods.

[0093] The compound having an isocyanate group is not particularly limited, but from the viewpoint of effectively increasing the adhesion between the ion barrier layer 11 and the adhesive layer, a polyfunctional isocyanate compound is preferably used. The polyfunctional isocyanate compound is not particularly limited as long as it has two or more isocyanate groups. Specific examples of polyfunctional isocyanate curing agents include pentane diisocyanate (PDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), polymers or nurates thereof, mixtures of these, and copolymers with other polymers. Other examples include adducts, biurets, and isocyanurates.

[0094] The content of the compound having an isocyanate group in the adhesive layer is preferably in the range of 0.1 to 50 mass %, more preferably in the range of 0.5 to 40 mass %, of the resin composition constituting the adhesive layer, which can effectively improve the adhesion between the ion barrier layer 11 and the adhesive layer.

[0095] 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 the Epocross series manufactured by Nippon Shokubai Co., Ltd.

[0096] The proportion of the compound having an oxazoline group in the adhesive layer is preferably in the range of 0.1 to 50 mass %, more preferably 0.5 to 40 mass %, of the resin composition constituting the adhesive layer, which can effectively improve the adhesion between the ion barrier layer 11 and the adhesive layer.

[0097] Examples of compounds having epoxy groups include epoxy resins. The epoxy resin is not particularly limited as long as it is a resin capable of forming a crosslinked structure by the epoxy groups present in the molecule, and known epoxy resins can be used. The weight-average molecular weight of the epoxy resin is preferably about 50 to 2,000, more preferably about 100 to 1,000, and even more 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) under conditions using polystyrene as a standard sample.

[0098] Specific examples of epoxy resins include glycidyl ether derivatives of trimethylolpropane, bisphenol A diglycidyl ether, modified bisphenol A diglycidyl ether, bisphenol F glycidyl ether, novolac glycidyl ether, glycerin polyglycidyl ether, polyglycerin polyglycidyl ether, etc. The epoxy resins may be used alone or in combination of two or more.

[0099] The proportion of the epoxy resin in the adhesive layer is preferably in the range of 0.1 to 50 mass %, more preferably 0.5 to 40 mass %, of the resin composition constituting the adhesive layer, which can effectively improve the adhesion between the ion barrier layer 11 and the adhesive layer.

[0100] The polyurethane is not particularly limited, and any known polyurethane can be used. The adhesive layer may be, for example, a cured product of a two-component curing polyurethane.

[0101] The proportion of polyurethane in the adhesive layer is preferably in the range of 0.1 to 50 mass %, more preferably 0.5 to 40 mass %, of the resin composition constituting the adhesive layer, which effectively enhances the adhesion between the ion barrier layer 11 and the adhesive layer in an atmosphere containing components that induce corrosion of the barrier layer, such as an electrolyte solution.

[0102] In addition, when the adhesive layer 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 the 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.

[0103] The adhesive layer may contain a modifier having a carbodiimide group.

[0104] When the adhesive layer is laminated with the ion barrier layer 11, the resin layer, or the like to produce the separation film 1 of the present disclosure, a pre-formed resin film may be used as the adhesive layer. Alternatively, the resin forming the adhesive layer may be formed into a film on the surface of the ion barrier layer 11, the resin layer, or the like by extrusion molding or coating, to form an adhesive layer formed from the resin film.

[0105] The thickness of the adhesive layer is preferably about 50 μm or less, about 40 μm or less, about 30 μm or less, about 20 μm or less, or about 5 μm or less. The thickness of the adhesive layer is preferably about 0.1 μm or more, or about 0.5 μm or more. The thickness of the adhesive layer 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, about 0.1 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, or about 0.5 to 5 μm. More specifically, in the case of the adhesives exemplified above or a cured product of an acid-modified polyolefin and a curing agent, the thickness is preferably about 1 to 10 μm, more preferably about 1 to 5 μm. Furthermore, when a resin exemplified for the resin layer is used, the thickness is preferably about 2 to 50 μm, more preferably about 10 to 40 μm. When the adhesive layer is a cured product of a resin composition containing the adhesive or acid-modified polyolefin and a curing agent, the adhesive layer can be formed, for example, by applying the resin composition and curing it by heating or the like. When a resin exemplified for the resin layer is used, the resin layer and adhesive layer can be formed, for example, by extrusion molding.

[0106] The adhesive layer may also contain a pigment, if necessary. Various inorganic pigments can be used as the pigment. A specific example of a pigment is carbon (carbon, graphite). As mentioned above, carbon (carbon, graphite) is a material commonly used inside electricity storage devices and is not likely to leach into the electrolyte. Furthermore, the coloring effect is significant, and a sufficient coloring effect can be obtained with an amount added that does not impair adhesion. Furthermore, the coloring effect does not melt due to heat, and the apparent melt viscosity of the added resin can be increased. Furthermore, the pressurized portion can be prevented from becoming thin during thermal bonding (heat sealing), thereby providing excellent sealing, for example, between the exterior material 30 and the release film 1.

[0107] When a pigment is added to the adhesive layer, the amount of pigment added is, for example, about 0.05 to 0.3 parts by mass, and preferably about 0.1 to 0.2 parts by mass, per 100 parts by mass of the resin component forming the adhesive layer when carbon black with a particle size of about 0.03 μm is used. By adding a pigment to the adhesive layer, the presence or absence of the separator film for an electricity storage device 1 can be detected by a sensor or visually inspected.

[0108] The thickness of the separator film 1 for an electricity storage device of the present disclosure is not particularly limited, but from the viewpoints of cost reduction, improvement of energy density, etc., examples include about 300 μm or less, preferably about 250 μm or less, about 210 μm or less, about 190 μm or less, about 180 μm or less, about 155 μm or less, and about 150 μm or less. Furthermore, from the viewpoints of ensuring mechanical strength and suitably separating a plurality of battery cells, the thickness of the separator film 1 for an electricity storage device is preferably about 35 μm or more, about 45 μm or more, or about 50 μm or more. Further, preferred ranges of the separator film 1 for electricity storage devices include, for example, about 35 to 300 μm, about 35 to 250 μm, about 35 to 210 μm, about 35 to 190 μm, about 35 to 180 μm, about 35 to 155 μm, about 35 to 150 μm, about 45 to 300 μm, about 45 to 250 μm, about 45 to 210 μm, about 45 to 190 μm, about 45 to 180 μm, about 45 to 155 μm, about 45 to 150 μm, about 50 to 300 μm, about 50 to 250 μm, about 50 to 210 μm, about 50 to 190 μm, about 50 to 180 μm, about 50 to 155 μm, and about 50 to 150 μm.

[0109] When the separator film 1 for an electricity storage device is composed of a laminate film, the ratio of the total thickness of the ion barrier layer 11, the resin layer provided as needed, and the adhesive layer provided as needed to the thickness (total thickness) of the laminate constituting the separator film 1 for an electricity storage device is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more. As a specific example, when the packaging material 30 of the present disclosure includes the ion barrier layer 11 and the resin layer 12, the ratio of the total thickness of these layers to the thickness (total thickness) of the laminate constituting the packaging material 30 is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more. Furthermore, when the packaging material 30 of the present disclosure includes the ion barrier layer 11, the resin layer 12, and the resin layer 13, the ratio of the total thickness of these layers to the thickness (total thickness) of the laminate constituting the packaging material 30 is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more. Furthermore, when the packaging material 30 of the present disclosure includes the ion barrier layer 11, the adhesive layer 14, and the resin layer 12, the ratio of the total thickness of these layers to the thickness (total thickness) of the laminate that constitutes the packaging material 30 is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more. Furthermore, when the packaging material 30 of the present disclosure includes the ion barrier layer 11, the adhesive layer 14, the resin layer 12, the adhesive layer 15, and the resin layer 15, the ratio of the total thickness of these layers to the thickness (total thickness) of the laminate that constitutes the packaging material 30 is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more.

[0110] [Sheathing Material 30] Examples of the sheathing material 30 include a metal member and a laminated film.

[0111] When the exterior material 30 is made of a metal material, the metal material may be stainless steel, copper, aluminum, an iron-aluminum clad material, etc. Specific examples of electricity storage devices made of metal materials include metal can batteries (rectangular can batteries, cylindrical can batteries), etc.

[0112] When the exterior packaging material 30 is made of a metal member, the thickness of the exterior packaging material 30 is not particularly limited, but from the viewpoint of cost reduction, improving energy density, etc., examples of the thickness include approximately 300 μm or less, and preferably approximately 250 μm or less, approximately 210 μm or less, approximately 190 μm or less, approximately 180 μm or less, approximately 155 μm or less, and approximately 120 μm or less. Furthermore, from the viewpoint of maintaining the function of the exterior packaging material to protect the battery cells, the thickness of the laminate that constitutes the exterior packaging material 30 is preferably approximately 35 μm or more, approximately 45 μm or more, approximately 60 μm or more, approximately 155 μm or more, and approximately 190 μm or more. Furthermore, preferred ranges for the laminate constituting the exterior packaging material 30 are, for example, about 35 to 300 μm, about 35 to 250 μm, about 35 to 210 μm, about 35 to 190 μm, about 35 to 180 μm, about 35 to 155 μm, about 35 to 120 μm, about 45 to 300 μm, about 45 to 250 μm, about 45 to 210 μm, about 45 to 190 μm, about 45 to 180 μm, about 45 to 155 μm, about 45 to 120 μm, about 60 to 300 μm, about 60 to 250 μm, and about 60 to 210 μm. μm, about 60 to 190 μm, about 60 to 180 μm, about 60 to 155 μm, about 60 to 120 μm, about 155 to 300 μm, about 155 to 250 μm, about 155 to 210 μm, about 155 to 190 μm, about 155 to 180 μm, about 190 to 300 μm, about 190 to 250 μm, about 190 to 210 μm, particularly when making the power storage device lightweight and thin, about 60 to 155 μm is preferred, and when improving formability, about 155 to 190 μm is preferred.

[0113] On the other hand, the exterior packaging material 30 made of a laminate film may have a laminate structure consisting of a laminate having at least a barrier layer 33 and a heat-sealable resin layer 35 in this order, for example. Figure 8 shows an example of the cross-sectional structure of the exterior packaging material 30, in which an optional base material layer 31, an optional adhesive layer 32, a barrier layer 33, an optional adhesive layer 34, and a heat-sealable resin layer 35 are laminated in this order. In the exterior packaging material 30, the barrier layer 33 is the outer layer, and the heat-sealable resin layer 35 is the innermost layer. When assembling the electricity storage device 10, the battery cell is sealed by sealing the heat-sealable resin layer 35 located in the peripheral edge portion 10a of the electricity storage device 10.

[0114] 1 to 3 illustrate the energy storage device 10 using an embossed exterior material 30 formed by embossing or the like, but the exterior material 30 may also be an unformed pouch type. Pouch types include three-sided sealed, four-sided sealed, and pillow-shaped types, and any of these types may be used. The same applies to cases where the exterior material 30 is made of a metal material. In the energy storage device of the present disclosure, a four-sided seal is preferred because it allows multiple battery cells to be suitably separated by a separation film. For example, in a four-sided seal, the peripheral portion 10a of the energy storage device 10 can be sealed all around by the exterior material 30 and the separation film 1.

[0115] The thickness of the laminate that constitutes the exterior material 30 is not particularly limited, but from the viewpoint of cost reduction, improving energy density, etc., the thickness may be, for example, about 300 μm or less, preferably about 250 μm or less, about 210 μm or less, about 190 μm or less, about 180 μm or less, about 155 μm or less, or about 120 μm or less. Furthermore, from the viewpoint of maintaining the function of the exterior material to protect the battery cells, the thickness of the laminate that constitutes the exterior material 30 may preferably be about 35 μm or more, about 45 μm or more, about 60 μm or more, about 155 μm or more, or about 190 μm or more. Furthermore, preferred ranges for the laminate constituting the exterior packaging material 30 are, for example, about 35 to 300 μm, about 35 to 250 μm, about 35 to 210 μm, about 35 to 190 μm, about 35 to 180 μm, about 35 to 155 μm, about 35 to 120 μm, about 45 to 300 μm, about 45 to 250 μm, about 45 to 210 μm, about 45 to 190 μm, about 45 to 180 μm, about 45 to 155 μm, about 45 to 120 μm, about 60 to 300 μm, about 60 to 250 μm, and about 60 to 210 μm. μm, about 60 to 190 μm, about 60 to 180 μm, about 60 to 155 μm, about 60 to 120 μm, about 155 to 300 μm, about 155 to 250 μm, about 155 to 210 μm, about 155 to 190 μm, about 155 to 180 μm, about 190 to 300 μm, about 190 to 250 μm, about 190 to 210 μm, particularly when making the power storage device lightweight and thin, about 60 to 155 μm is preferred, and when improving formability, about 155 to 190 μm is preferred.

[0116] (Substrate layer 31) The substrate layer 31 is a layer that is provided as needed in the packaging material 30. The substrate layer 31 is a layer that functions as a substrate for the packaging material and forms the outermost layer side.

[0117] The material for forming the substrate layer 31 is not particularly limited, as long as it has insulating properties. Examples of materials for forming the substrate layer 31 include polyester, polyamide, epoxy, acrylic, fluororesin, polyurethane, silicone resin, phenol, polyetherimide, polyimide, and mixtures or copolymers thereof. Polyesters such as polyethylene terephthalate have the advantage of being highly resistant to electrolyte and being less susceptible to whitening due to adhesion of electrolyte, and are therefore preferably used as a material for forming the substrate layer 31. Furthermore, polyamide film has excellent stretchability and can prevent whitening due to resin cracking of the substrate layer 31 during molding, and is therefore preferably used as a material for forming the substrate layer 31.

[0118] The base layer 31 may be formed of a uniaxially or biaxially stretched resin film or an unstretched resin film. Among them, a uniaxially or biaxially stretched resin film, especially a biaxially stretched resin film, is preferably used as the base layer 31 because its heat resistance is improved by oriented crystallization.

[0119] Among these, the resin film forming the base layer 31 is preferably nylon or polyester, and more preferably biaxially oriented nylon or biaxially oriented polyester.

[0120] The base material layer 31 may be formed by laminating resin films made of different materials to improve pinhole resistance and insulation when used as a package for an electricity storage device. Specific examples include a multilayer structure in which a polyester film and a nylon film are laminated together, or a multilayer structure in which a biaxially oriented polyester film and a biaxially oriented nylon film are laminated together. When the base material layer 31 has a multilayer structure, the resin films may be bonded together via an adhesive, or may be directly laminated together without an adhesive. Bonding without an adhesive can be achieved by, for example, a method of bonding in a hot-melt state, such as coextrusion, sand lamination, or thermal lamination. For the above-mentioned high-temperature sealing, it is desirable that at least the outermost layer be made of biaxially oriented polyester.

[0121] The base layer 31 may be made low-friction to improve formability. When making the base layer 31 low-friction, the coefficient of friction of the surface is not particularly limited, but may be, for example, 1.0 or less. To make the base layer 31 low-friction, for example, matte treatment, formation of a thin film layer of a slip agent, or a combination thereof may be used.

[0122] The thickness of the base layer 31 is, for example, about 10 to 50 μm, and preferably about 15 to 30 μm.

[0123] (Adhesive Layer 32) In the packaging material 30, the adhesive layer 32 is a layer that is disposed on the base material layer 31 as necessary in order to impart adhesion to the base material layer 31. That is, the adhesive layer 32 is provided between the base material layer 31 and the barrier layer 33.

[0124] The adhesive layer 32 is formed of an adhesive capable of bonding the base material layer 31 and the barrier layer 33. The adhesive used to form the adhesive layer 32 may be a two-component curing adhesive or a one-component curing adhesive. The bonding mechanism of the adhesive used to form the adhesive layer 32 is not particularly limited, and may be any of a chemical reaction type, a solvent volatilization type, a hot melt type, a hot pressure type, or the like.

[0125] The resin component of the adhesive that can be used to form the adhesive layer 32 is preferably a polyurethane-based two-component curing adhesive; polyamide, polyester, or a blend resin of these with modified polyolefin, from the viewpoint of having excellent ductility, durability under high humidity conditions, yellowing prevention, and thermal degradation prevention during heat sealing, and of effectively suppressing a decrease in the laminate strength between the base material layer 31 and the barrier layer 33 and preventing delamination.

[0126] Furthermore, the adhesive layer 32 may be multi-layered with different adhesive components. When the adhesive layer 32 is multi-layered with different adhesive components, it is preferable to select a resin that has excellent adhesion to the base material layer 31 as the adhesive component disposed on the base material layer 31 side, and an adhesive component that has excellent adhesion to the barrier layer 33 as the adhesive component disposed on the barrier layer 33 side, from the viewpoint of improving the laminate strength between the base material layer 31 and the barrier layer 33. When the adhesive layer 32 is multi-layered with different adhesive components, specifically, the adhesive component disposed on the barrier layer 33 side is preferably an acid-modified polyolefin, a metal-modified polyolefin, a mixed resin of polyester and acid-modified polyolefin, a resin containing a copolymer polyester, or the like.

[0127] The thickness of the adhesive layer 32 is, for example, about 2 to 50 μm, and preferably about 3 to 25 μm.

[0128] (Barrier Layer 33) In the exterior packaging material, the barrier layer 33 is a layer that not only improves the strength of the exterior packaging material but also has the function of preventing water vapor, oxygen, light, and the like from penetrating into the interior of the electricity storage device. The barrier layer 33 is preferably a metal layer, i.e., a layer formed of a metal. Specific examples of metals constituting the barrier layer 33 include aluminum, stainless steel, and titanium, and aluminum is preferred. The barrier layer 33 can be formed, for example, from a metal foil, a metal vapor deposition film, an inorganic oxide vapor deposition film, a carbon-containing inorganic oxide vapor deposition film, or a film provided with any of these vapor deposition films. It is preferably formed from a metal foil, and more preferably from an aluminum foil. From the viewpoint of preventing the occurrence of wrinkles or pinholes in the barrier layer 33 during the production of the exterior packaging material, the barrier layer is more preferably formed from a soft aluminum foil such as annealed aluminum (JIS H4160:1994 A8021H-O, JIS H4160:1994 A8079H-O, JIS H4000:2014 A8021P-O, JIS H4000:2014 A8079P-O).

[0129] In the barrier layer 33, the layer made of the aforementioned metal material may contain recycled metal material. Examples of recycled metal material include recycled aluminum alloy, stainless steel, titanium steel, and steel plate. These recycled materials can be obtained by known methods. Recycled aluminum alloy material can be obtained, for example, by the manufacturing method described in International Publication No. 2022 / 092231. The barrier layer 33 may be made of recycled material alone, or may be made of a mixture of recycled and virgin material. Note that recycled metal material refers to metal material that has been made reusable by collecting, isolating, and refining various products used in the market or waste from manufacturing processes. Furthermore, virgin metal material refers to new metal material refined from natural metal resources (raw materials) and is not recycled material.

[0130] The thickness of the barrier layer 33 is preferably about 10 to 200 μm, more preferably about 20 to 100 μm, about 20 to 45 μm, about 45 to 65 μm, or about 65 to 85 μm, from the viewpoint of making the exterior material thinner while making it less likely to develop pinholes during molding.

[0131] Furthermore, it is preferable that at least one surface, and preferably both surfaces, of the barrier layer 33 be chemically treated in order to stabilize adhesion, prevent dissolution and corrosion, etc. Here, chemical treatment refers to a treatment for forming a corrosion-resistant film on the surface of the barrier layer.

[0132] (Adhesive Layer 34) In the exterior packaging material 30, the adhesive layer 34 is a layer that is provided as needed between the barrier layer 33 and the heat-sealable resin layer 35 in order to firmly bond the heat-sealable resin layer 35.

[0133] The adhesive layer 34 is formed of an adhesive capable of bonding the barrier layer 33 and the heat-fusible resin layer 35. The composition of the adhesive used to form the adhesive layer is not particularly limited, but examples thereof include an adhesive made of a polyester polyol compound and an alicyclic isocyanate compound.

[0134] The thickness of the adhesive layer 34 is, for example, about 1 to 40 μm, and preferably about 2 to 30 μm.

[0135] (Heat-sealable resin layer 35) In the exterior packaging material 30, the heat-sealable resin layer 35 corresponds to the innermost layer, and is a layer that seals the battery cells with the heat-sealable resin layer when assembling the electricity storage device.

[0136] The resin component used in the heat-fusible resin layer 35 is not particularly limited as long as it is heat-fusible, but for example, in the case of exterior materials, polyolefins and cyclic polyolefins are generally used.

[0137] Specific examples of the polyolefin include polyethylenes such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; crystalline or amorphous polypropylenes such as homopolypropylene, block copolymers of polypropylene (e.g., block copolymers of propylene and ethylene), and random copolymers of polypropylene (e.g., random copolymers of propylene and ethylene); and ethylene-butene-propylene terpolymers. Among these polyolefins, polyethylene and polypropylene are preferred.

[0138] 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, butadiene, and isoprene. Examples of the cyclic monomer constituting the cyclic polyolefin include cyclic alkenes such as norbornene; specifically, cyclic dienes such as cyclopentadiene, dicyclopentadiene, cyclohexadiene, and norbornadiene. Among these polyolefins, preferred are cyclic alkenes, and more preferred are norbornene. Another example of the constituting monomer is styrene.

[0139] Among these resin components, preferred are crystalline or amorphous polyolefins, cyclic polyolefins, and blend polymers thereof; more preferred are polyethylene, polypropylene, copolymers of ethylene and norbornene, and blend polymers of two or more of these.

[0140] The heat-sealable resin layer 35 may be formed of one type of resin component alone, or may be formed of a blend polymer of two or more types of resin components. Furthermore, the heat-sealable resin layer 35 may be formed of only one layer, or may be formed of two or more layers of the same or different resin components.

[0141] The thickness of the heat-fusible resin layer 35 is not particularly limited, but may be about 2 to 2000 μm, preferably about 5 to 1000 μm, and more preferably about 10 to 500 μm.

[0142] The heat-sealable resin layer 35 may be formed of only one layer, or may be formed of two or more layers of the same or different resins. When the heat-sealable resin layer 35 is formed of two or more layers, the layers not formed of polybutylene terephthalate film may be formed of, for example, polyolefins such as polypropylene and polyethylene, or acid-modified polyolefins such as acid-modified polypropylene and acid-modified polyethylene. However, since polyolefins and acid-modified polyolefins have lower durability in high-temperature environments than polybutylene terephthalate and polyethylene terephthalate, it is preferable that the heat-sealable resin layer 35 be formed of only polybutylene terephthalate film, such as a homo-PBT layer or copolymer PBT layer, or only polyethylene terephthalate, such as a PET layer.

[0143] It is also preferable that the resin layer forming the surface of the electricity storage device separator film 1 on the side of the exterior packaging material is the same as the resin constituting the heat-sealable resin layer 35. The resin layer forming the surface of the electricity storage device separator film 1 on the side of the exterior packaging material and the resin constituting the heat-sealable resin layer 35 being the same means that, for example, 80% by mass or more of the components in these resins are the same, 90% by mass or more of the same, 95% by mass or more of the same, or 100% by mass of the same.

[0144] [Terminals 2a, 2b] The terminals 2a and 2b (tabs) are conductive members electrically connected to the electrodes (positive or negative electrodes) of the battery cell, and are typically made of a metal material (i.e., metal terminals). The metal material constituting the terminals 2a and 2b is not particularly limited, and examples thereof include aluminum, nickel, and copper. For example, the terminals 2a and 2b connected to the positive electrode of a lithium ion storage device are typically made of aluminum. The terminals 2a and 2b connected to the negative electrode of a lithium ion storage device are typically made of copper, nickel, or the like, and from the viewpoints of low resistance and prevention of surface deterioration, they are typically made of nickel-plated copper or a nickel-copper clad material.

[0145] The surfaces of the terminals 2a and 2b are preferably subjected to a chemical conversion treatment in order to enhance electrolyte resistance. For example, when the terminals 2a and 2b are made of aluminum, specific examples of the chemical conversion treatment include known methods for forming corrosion-resistant coatings using phosphates, chromates, fluorides, triazine thiol compounds, etc. Among the methods for forming corrosion-resistant coatings, a preferred method is a chromate phosphate treatment using a three-component solution consisting of a phenolic resin, a chromium (III) fluoride compound, and phosphoric acid.

[0146] The size of the terminals 2a and 2b may be set appropriately depending on the size of the electricity storage device 10 to be used. The thickness of the terminals 2a and 2b is preferably about 50 to 1000 μm, more preferably about 70 to 800 μm. The length of the terminals 2a and 2b is preferably about 1 to 200 mm, more preferably about 3 to 150 mm. The width of the terminals 2a and 2b is preferably about 1 to 200 mm, more preferably about 3 to 150 mm.

[0147] [Electricity storage device] The electricity storage device 10 of the present disclosure includes at least an exterior material 30, a plurality of battery cells sealed by the exterior material 30, and a separator film 1 of the present disclosure arranged to separate the plurality of battery cells, and the plurality of battery cells are electrically connected in series.

[0148] As described above, in the electricity storage device 10 of the present disclosure, the multiple battery cells are two battery cells 21, 22 in Figures 2 and 9 to 11, and three battery cells 21, 22, 23 in Figure 3. There are no particular restrictions on the number of battery cells included in the electricity storage device 10 of the present disclosure, but from the viewpoint of suitably separating the multiple battery cells with the separator film 1 of the present disclosure, the number is preferably about 2 to 5, and more preferably 2 to 3.

[0149] The separator film 1 of the present disclosure is arranged inside the exterior material 30 of the electricity storage device 10 so as to separate multiple battery cells into individual battery cells. Each battery cell contains an electrode and an electrolyte, and without the separator film 1 of the present disclosure arranged, the individual battery cells would be electrically connected through the electrolyte within the electricity storage device 10, preventing the achievement of high voltages by connecting multiple battery cells in series outside the exterior material. The separator film 1 of the present disclosure includes an ion barrier layer 11, and therefore prevents the multiple cells sealed within the electricity storage device from being electrically connected through the electrolyte.

[0150] For example, in the electricity storage device 10 shown in Figures 1 and 2, a plurality of battery cells, battery cells 21 and 22, are separated by a separator film 1. In Figures 1 and 2, the exterior material 30 is composed of two members, a first exterior material 30a and a second exterior material 30b, and the first exterior material 30a and the second exterior material 30b are sealed at the peripheral edge 10a of the electricity storage device 10 with a separator film 1 between them, thereby separating the battery cells 21 and 22. In Figures 1 and 2, the battery cells 21 are sealed by the first exterior material 30a and the separator film 1, and the battery cells 22 are sealed by the second exterior material 30b and the separator film 1.

[0151] 9 to 11 are schematic diagrams assuming that the exterior casing 30 is made of metal (for example, a metal can battery). When the exterior casing is made of metal, the terminals 2a and 2b do not need to be drawn out from the sealed portion of the exterior casing, and the terminals 2a and 2b can be drawn out by penetrating the exterior casing 30. In the electricity storage device 10 shown in FIGS. 9 to 11, the terminals 2b are also electrically connected in series outside the exterior casing 30.

[0152] 1 and 2 , the separator film 1 located between the first exterior material 30a and the second exterior material 30b is bonded (for example, by welding, heat fusion, etc.) to the first exterior material 30a and the second exterior material 30b, thereby sealing the multiple battery cells with the exterior material 30. For example, if the surface of the separator film 1 is made of metal and the exterior material 30 is also made of metal, the separator film 1 and the exterior material 30 can be bonded by metal welding. The same applies to the electricity storage device 10 in FIGS. 9 to 11 . On the other hand, if the surface of the separator film is made of resin, they can be bonded by heat fusion whether the exterior material is made of metal or is a laminate including the above-mentioned heat-sealable resin layer 35.

[0153] 1 and 2, at the positions where the terminals 2a and 2b are present, the first exterior material 30a and the second exterior material 30b are adhered to the terminals 2a and 2b, and the separation film 1 is also adhered to the terminals 2a and 2b. The terminals 2a and 2b are usually made of metal. Therefore, when the exterior material 30 is made of metal, the exterior material 30 and the terminals 2a and 2b can be adhered by metal welding. Furthermore, when the exterior material 30 is made of a laminate including the above-mentioned heat-sealable resin layer 35, the exterior material 30 and the terminals 2a and 2b can be adhered by heat fusion. Furthermore, when the surface of the separation film 1 is made of metal, the separation film 1 and the terminals 2a and 2b can be adhered by metal welding. Furthermore, when the surface of the separation film 1 is made of resin, the separation film 1 and the terminals 2a and 2b can be adhered by heat fusion.

[0154] Furthermore, for example, in the energy storage device 10 shown in Fig. 3, a plurality of battery cells, that is, battery cell 21, battery cell 22, and battery cell 23, are separated by a separator film 1. In Fig. 3, two separator films 1 are used. In this way, in the energy storage device of the present disclosure, three or more battery cells can be separated by using a plurality of separator films 1. In Fig. 3, the exterior material 30 is composed of two members, a first exterior material 30a and a second exterior material 30b, and the first exterior material 30a and the second exterior material 30b are sealed at the peripheral edge 10a of the energy storage device 10 with the two separator films 1 interposed therebetween, thereby separating the battery cells 21, battery cell 22, and battery cell 23. In Fig. 3, battery cell 21 is sealed by first exterior material 30a and release film 1, battery cell 22 is sealed by release film 1, and battery cell 23 is sealed by second exterior material 30b and release film 1. As shown in Fig. 3, the release film 1 of the present disclosure may be formed into a battery cell housing portion by deep drawing, bulging, or the like.

[0155] 3 , the release film 1 located between the first exterior material 30a and the second exterior material 30b is bonded (for example, by welding, heat fusion, etc.) to the first exterior material 30a and the second exterior material 30b, thereby sealing the multiple battery cells with the exterior material 30. For example, if the surface of the release film 1 is made of metal and the exterior material 30 is also made of metal, the release film 1 and the exterior material 30 can be bonded by metal welding. On the other hand, if the surface of the release film is made of resin, the separation film 1 and the exterior material 30 can be bonded by heat fusion, whether the exterior material is made of metal or is a laminate including the heat-sealable resin layer 35 described above.

[0156] 3, the two separation films 1 are also bonded at positions where the separation film 1 is bonded to the exterior material 30. For example, if the surface of the separation film 1 is made of metal, the two separation films 1 can be bonded by metal welding. Also, for example, if the surface of the separation film 1 is made of resin, the two separation films 1 can be bonded by heat fusion.

[0157] 3, at the positions where the terminals 2a and 2b are present, the first exterior material 30a and the second exterior material 30b are adhered to the terminals 2a and 2b, and the separation film 1 is also adhered to the terminals 2a and 2b. The terminals 2a and 2b are usually made of metal. Therefore, when the exterior material 30 is made of metal, the exterior material 30 and the terminals 2a and 2b can be adhered by metal welding. Furthermore, when the exterior material 30 is made of a laminate including the above-mentioned heat-sealable resin layer 35, the exterior material 30 and the terminals 2a and 2b can be adhered by heat fusion. Furthermore, when the surface of the separation film 1 is made of metal, the separation film 1 and the terminals 2a and 2b can be adhered by metal welding. Furthermore, when the surface of the separation film 1 is made of resin, the separation film 1 and the terminals 2a and 2b can be adhered by heat fusion.

[0158] In addition, in the peripheral portion 10a of the energy storage device 10, an adhesive film (not shown) may be placed in the area where the terminals 2a and 2b are bonded to the exterior material 30 and the separation film 1 in order to enhance the adhesion of the terminals 2a and 2b by thermal fusion.

[0159] In the energy storage device 10 of the present disclosure, the plurality of battery cells are electrically connected in series. For example, in Fig. 2, the battery cells 21 and 22 each include a terminal 2a and a terminal 2b electrically connected to the electrodes of the battery cell. The terminals 2a and 2b are drawn out from the inside (battery cell side) of the exterior material 30 of the energy storage device 10 to the outside. The terminals 2a and 2b of the battery cells 21 and 22 are connected in series. In Fig. 2, the positive electrode (+) of the battery cell 21 and the negative electrode (-) of the battery cell 22 are electrically connected outside the exterior material 30, thereby connecting the battery cells 21 and 22 in series.

[0160] 3, terminals 2a and 2b are not drawn, but battery cells 21, 22, and 23 are connected in series outside the exterior material 30. Connecting battery cells in series can increase the voltage of the power storage device 10. For example, in FIG. 3, if the voltage of each of battery cells 21, 22, and 23 is 3.7 V, connecting battery cells 21, 22, and 23 in series can increase the voltage of the entire power storage device 10 to 3.7 V x 3 = 11.1 V.

[0161] The energy storage device of the present disclosure can be manufactured, for example, by a manufacturing method including the steps of: sealing the multiple battery cells with an exterior material 30 in a state in which a separation film is arranged so that the multiple battery cells are separated into individual battery cells within the energy storage device 10; and electrically connecting the multiple battery cells in series.

[0162] The power storage device of the present disclosure can be suitably used in power storage devices such as batteries (including condensers, capacitors, etc.). The exterior material of the present disclosure may be used in either primary or secondary batteries, but is preferably used in secondary batteries. The type of secondary battery to which the exterior material of the present disclosure is applied is not particularly limited, and examples include lithium ion batteries, lithium ion polymer batteries, all-solid-state batteries, semi-solid batteries, quasi-solid batteries, polymer batteries, all-resin batteries, lead-acid batteries, nickel-metal hydride batteries, nickel-cadmium batteries, nickel-iron batteries, nickel-zinc batteries, silver oxide-zinc batteries, metal-air batteries, polyvalent cation batteries, condensers, and capacitors. Among these secondary batteries, lithium ion batteries and lithium ion polymer batteries are suitable applications for the exterior material of the present disclosure.

[0163] Among these, the separator film for an electricity storage device 1 of the present disclosure can be suitably applied to all-solid-state batteries.

[0164] As described above, the present disclosure provides the following aspects of the invention. Item 1. A separator film for an electricity storage device used to separate multiple battery cells included in the electricity storage device within the electricity storage device, wherein the electricity storage device includes at least an exterior material, the multiple battery cells sealed with the exterior material, and the separator film arranged to separate the multiple battery cells, the multiple battery cells being electrically connected in series, and the separator film including an ion barrier layer. Item 2. The separator film for an electricity storage device according to Item 1, wherein the exterior material is made of metal. Item 3. The separator film for an electricity storage device according to Item 1, wherein the exterior material is made of a laminate including at least a barrier layer and a heat-sealable resin layer. Item 4. The separator film for an electricity storage device according to any one of Items 1 to 3, wherein the separator film further includes a resin layer on at least one side of the ion barrier layer. Item 5. Item 6. An electricity storage device separator film according to any one of Items 1 to 4, wherein the separator film has a thickness of 10 μm or more and 200 μm or less. Item 6. An electricity storage device comprising at least an exterior material, a plurality of battery cells sealed with the exterior material, and a separator film arranged so as to separate the plurality of battery cells, wherein the plurality of battery cells are electrically connected in series, and the separator film includes an ion barrier layer. Item 7. The electricity storage device according to Item 6, wherein the exterior material is made of metal. Item 8. The electricity storage device according to Item 6, wherein the exterior material is made of a laminate including at least a barrier layer and a heat-sealable resin layer. Item 9. The electricity storage device according to any one of Items 6 to 8, wherein the separator film further includes a resin layer on at least one side of the ion barrier layer. Item 10. The electricity storage device according to any one of Items 6 to 9, wherein the separator film has a thickness of 10 μm or more and 200 μm or less. Item 11. Item 11. The electricity storage device according to any one of items 6 to 10, wherein a peripheral portion of the electricity storage device is sealed by the exterior material and the separation film over the entire periphery.Item 12. A method for manufacturing an electricity storage device, wherein the electricity storage device includes at least an exterior material, a plurality of battery cells, and a separator film, wherein the separator film includes an ion barrier layer, and the method includes the steps of: sealing the plurality of battery cells with the exterior material in a state where the separator film is arranged so that the plurality of battery cells are separated into individual battery cells within the electricity storage device; and electrically connecting the plurality of battery cells in series. Item 13. A method for manufacturing a separator film used to separate a plurality of battery cells included in an electricity storage device within the electricity storage device, wherein the electricity storage device includes at least an exterior material, the plurality of battery cells sealed with the exterior material, and the separator film arranged so as to separate the plurality of battery cells, wherein the plurality of battery cells are electrically connected in series, and the separator film includes an ion barrier layer.

[0165] REFERENCE SIGNS LIST 1 Separation film for electricity storage device 2a Terminal 2b Terminal 10 Electricity storage device 10a Peripheral edge of electricity storage device 11 Ion barrier layer 12 Resin layer 13 Resin layer 14 Adhesive layer 15 Adhesive layer 21 Battery cell 22 Battery cell 23 Battery cell 30 Exterior material for electricity storage device 30a First exterior material 30b Second exterior material 31 Base material layer 32 Adhesive layer 33 Barrier layer 34 Adhesive layer 35 Heat-sealable resin layer

Claims

1. A separator film for an electricity storage device, used to separate multiple battery cells included in the electricity storage device within the electricity storage device, wherein the electricity storage device includes at least an exterior material, the multiple battery cells sealed by the exterior material, and the separator film arranged to separate the multiple battery cells, the multiple battery cells being electrically connected in series, and the separator film including an ion barrier layer.

2. The separator film for an electricity storage device according to claim 1, wherein the exterior material is made of metal.

3. The separator film for an electricity storage device according to claim 1, wherein the exterior material is composed of a laminate including at least a barrier layer and a heat-sealable resin layer.

4. The separator film for an electricity storage device according to any one of claims 1 to 3, further comprising a resin layer on at least one side of the ion barrier layer.

5. The separator film for an electricity storage device according to any one of claims 1 to 3, wherein the thickness of the separator film is 10 µm or more and 200 µm or less.

6. An electricity storage device comprising at least an exterior material, a plurality of battery cells sealed by the exterior material, and a separator film arranged to separate the plurality of battery cells, wherein the plurality of battery cells are electrically connected in series, and the separator film includes an ion barrier layer.

7. The electricity storage device according to claim 6, wherein the exterior material is made of metal.

8. The electricity storage device according to claim 6, wherein the exterior material is composed of a laminate including at least a barrier layer and a heat-sealable resin layer.

9. The electricity storage device according to any one of claims 6 to 8, wherein the separator film further comprises a resin layer on at least one side of the ion barrier layer.

10. The electricity storage device according to any one of claims 6 to 8, wherein the thickness of the separation film is 10 μm or more and 200 μm or less.

11. The electricity storage device according to any one of claims 6 to 8, wherein the entire periphery of the electricity storage device is sealed with the exterior material and the release film.

12. A method for manufacturing an electricity storage device, wherein the electricity storage device includes at least an exterior material, a plurality of battery cells, and a separation film, the separation film including an ion barrier layer, the method comprising: a step of sealing the plurality of battery cells with the exterior material in a state in which the separation film is arranged so that the plurality of battery cells are separated into individual battery cells within the electricity storage device; and a step of electrically connecting the plurality of battery cells in series.

13. A method for manufacturing a separator film for an electricity storage device, the method comprising: separating a plurality of battery cells included in the electricity storage device within the electricity storage device; the electricity storage device including at least an exterior material, the plurality of battery cells sealed by the exterior material, and the separator film arranged to separate the plurality of battery cells; the plurality of battery cells being electrically connected in series; and the separator film including an ion barrier layer.

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