JP7195751B2 - Membrane for electrochemical device and use thereof - Google Patents

Description

TECHNICAL FIELD The present invention relates to a diaphragm for an electrochemical device. More particularly, the present invention relates to a separation film for electrochemical elements which has excellent adhesion between an organic layer and a support and excellent gas barrier properties.

Laminated films composed of an organic layer and a support have been studied for various uses, and laminated films having excellent properties required for each use have been developed. As one of the uses of such a laminated film, a diaphragm for electrochemical devices such as a diaphragm for alkaline water electrolysis and a battery separator is known.

For example, a diaphragm for alkaline water electrolysis is a membrane used for water electrolysis, which is one of the industrial production methods of hydrogen, and is used to separate an anode chamber and a cathode chamber in an electrolytic cell.
Electrolysis of water is performed by the transfer of electrons (or ions). Therefore, in order to perform electrolysis efficiently, the diaphragm for alkaline water electrolysis is required to have high ion permeability. In addition, it is required to have gas barrier properties capable of blocking oxygen generated in the anode chamber and hydrogen generated in the cathode chamber. Furthermore, since the electrolysis of water is performed at 80 to 90° C. using high-concentration alkaline water of about 30%, high temperature resistance and alkali resistance are also required.

A battery separator is a film used for the purpose of insulating the positive electrode and the negative electrode in a battery such as a zinc secondary battery. Used to ensure conductivity. In battery separators, dendrites grow as the battery is charged and discharged, which can cause short circuits. Therefore, battery separators are required to have ion conductivity and to be able to suppress the formation of dendrites as much as possible.

Various types of such electrochemical device diaphragms have been known so far.
For example, Patent Document 1 discloses an ion-permeable membrane and a porous reinforcing member disposed on one side or both sides of the ion-permeable membrane, wherein the ion-permeable membrane has moderately acidic ion-exchange groups and weakly acidic ion-exchange groups. , a polymer having a strongly basic ion-exchange group, a moderately basic ion-exchange group, or a weakly basic ion-exchange group, and the porous reinforcing body exhibits wettability to an aqueous potassium hydroxide solution having a concentration of 30% by weight. A diaphragm for alkaline water electrolysis is described.
Further, for example, Patent Document 2 discloses a substrate for an alkaline water electrolysis diaphragm composed of thermoplastic fibers having an average single fiber fineness and a crimp number within a specific range, and an alkaline water electrolysis membrane in which the substrate comprises a nonwoven fabric. Substrates for diaphragms are described.

JP 2013-249509 A JP 2016-89197 A

However, conventional diaphragms for electrochemical devices having an organic layer and a support have a problem that the adhesion between the organic layer and the support is insufficient, resulting in poor gas barrier properties. In addition, due to the recent progress in energy technology, the performance required of membranes for electrochemical devices is increasing, and there is room for improvement.

It is an object of the present invention to provide a membrane for an electrochemical device, which has excellent adhesion between an organic layer and a support and can exhibit excellent gas barrier properties.

The inventor of the present invention has made various studies on a diaphragm for an electrochemical device having an organic layer containing a binder polymer and a support. The present inventors found that by using a hydrocarbon-based porous material having a group and an oxygen element concentration within a specific range, the adhesion between the organic layer and the support is excellent and the gas barrier property is remarkably improved. I have completed my invention.

That is, the present invention provides a diaphragm for an electrochemical device comprising an organic layer containing a binder polymer and a support, wherein the organic layer further contains inorganic compound particles, and the support has a hydrophilic functional group. The hydrocarbon-based porous body having a hydrophilic functional group has an oxygen element concentration of 10 atm per 100 atm % of carbon element in the element concentration measured by X-ray photoelectron spectroscopy (ESCA). % or more.

The hydrocarbon-based porous body having a hydrophilic functional group further has a sulfur element concentration of 0.5 atm% or more with respect to 100 atm% of carbon element in the element concentration measured by X-ray photoelectron spectroscopy (ESCA). is preferred.

The hydrocarbon-based porous material having a hydrophilic functional group further has a fluorine element concentration of 3.5 atm% or more with respect to 100 atm% of carbon element in the element concentration measured by X-ray photoelectron spectroscopy (ESCA). is preferred.

The diaphragm for an electrochemical device of the present invention has extremely excellent adhesion between the organic layer constituting the diaphragm and the support. Therefore, the diaphragm for an electrochemical device of the present invention has excellent gas barrier properties. The diaphragm for an electrochemical device of the present invention is particularly suitable for use as a diaphragm for alkaline water electrolysis or a battery separator.

The present invention will be described in detail below.
A combination of two or more of the individual preferred embodiments of the invention described below is also a preferred embodiment of the invention.

1. Membrane for electrochemical element The diaphragm for electrochemical element of the present invention is a diaphragm for electrochemical element comprising an organic layer containing a binder polymer and a support, wherein the organic layer further contains inorganic compound particles, The support is a hydrocarbon-based porous body having a hydrophilic functional group, and the hydrocarbon-based porous body having the hydrophilic functional group has an element concentration measured by X-ray photoelectron spectroscopy (ESCA), It is characterized in that the concentration of oxygen element is 10 atm % or more with respect to 100 atm % of carbon element.
Since the diaphragm for an electrochemical device of the present invention has the above structure, it has excellent adhesion between the support and the organic layer constituting the diaphragm, and has excellent gas barrier properties.

In the membrane for an electrochemical element of the present invention, hydrogen bonds are formed between the binder polymer and the inorganic compound particles and the hydrophilic functional groups of the support at the interface between the organic layer and the support, and If the hydrophilic functional group is contained, when the support is impregnated with the organic layer-forming material, the impregnation property of the material for forming the organic layer is improved, and the support and the organic layer are easily combined. The interface between the polymer and the support and the adhesion inside the support are excellent.
As a result, gas is less likely to pass through the diaphragm, and it is presumed that excellent gas barrier properties are exhibited.

A diaphragm for an electrochemical device of the present invention includes an organic layer and a support. Each configuration will be described below.
<Organic layer>
The organic layer contains a binder polymer and further contains inorganic compound particles. When the organic layer contains inorganic compound particles in addition to the binder polymer, the adhesion to the support described later can be excellent. Thus, the organic layer is preferably an inorganic-organic composite layer containing a binder polymer and inorganic compound particles.

(Inorganic compound particles)
Examples of the inorganic compound particles include particles made of a compound containing at least one element selected from Groups 1 to 17 of the periodic table. The at least one element selected from Groups 1 to 17 of the periodic table is preferably at least one element selected from Groups 1 to 15 of the periodic table, Groups 2, 4 and At least one element selected from Group 6 is more preferable, and among them, at least one element selected from Mg, Ca, Sr, Ba, Ti, Zr, Hf, Cr, Mo and W is more preferable, Mg, Ti , Zr and Mo are particularly preferred.

The inorganic compound particles are preferably oxides, hydroxides, or compounds containing a hydroxide layer, and more preferably oxides, hydroxides, or compounds containing a hydroxide layer containing the above preferred elements.
Among them, the inorganic compound particles include hydroxides containing Mg, Ca, Sr or Ba or compounds containing a hydroxide layer, Mg, Ca , Sr, Ba, Ti, Zr, Hf, Cr, Mo and W are preferred, and hydroxides containing Mg or compounds containing hydroxide layers, Mg, Ti, Zr and Mo are more preferred.

As the hydroxide containing Mg or the compound containing a hydroxide layer, magnesium hydroxide and hydrotalcite are preferable, and magnesium hydroxide is more preferable.
As the oxide containing at least one element selected from Mg, Ti, Zr and Mo, magnesium oxide, titanium oxide, zirconium oxide, molybdenum oxide, and solid solutions in which different elements are dissolved in these oxides are preferable.
By using the preferred inorganic compound particles described above, the adhesion between the organic layer and the support can be further increased, and excellent gas barrier properties can be exhibited.

The above inorganic compound particles may be used alone or in combination of two or more.

Examples of the shape of the inorganic compound particles include amorphous, fine powder, powdery, granular, granular, flaky, polyhedral, rod-like, and curved surface-containing shapes. Among them, fine powder and flakes are preferable from the viewpoint that the adhesiveness between the organic layer and the support can be further enhanced and excellent gas barrier properties can be exhibited.

The inorganic compound particles preferably have an average particle size of 0.001 μm or more, more preferably 0.05 μm or more, and even more preferably 0.1 μm or more. Also, it is preferably 10 μm or less, more preferably 2.0 μm or less, and even more preferably 1.5 μm or less.
The average particle size is a volume average particle size (D50) obtained from particle size distribution measurement by laser diffraction method. Specifically, the average particle diameter is obtained by dispersing the inorganic compound particles in ethanol and subjecting them to ultrasonic treatment, using a laser diffraction/scattering particle size distribution analyzer (manufactured by Horiba, Ltd. "model number LA-920"). can be obtained by adjusting the transmittance to that specified by the apparatus and measuring it.

The content of the inorganic compound particles is preferably 30% by mass or more, more preferably 32% by mass or more, and more preferably 35% by mass or more with respect to 100% by mass of the diaphragm for an electrochemical element. preferable. In addition, the content of the inorganic compound particles is preferably 99% by mass or less, more preferably 45% by mass or less, and 43% by mass or less with respect to 100% by mass of the diaphragm for an electrochemical device. is more preferred.

Further, with respect to 100 parts by mass of the inorganic compound particles, it preferably contains 1 part by mass or more of the binder polymer, more preferably 22 parts by mass or more, more preferably 25 parts by mass or more, and 67 parts by mass or less. preferably 42 parts by mass or less, and even more preferably 40 parts by mass or less.

(binder polymer)
Examples of the binder polymer include aliphatic hydrocarbon group-containing polymers such as polyethylene; aromatic hydrocarbon group-containing polymers such as polystyrene; ether group-containing polymers such as alkylene glycol; hydroxyl group-containing polymers such as polyvinyl alcohol; amide group-containing polymers; imide group-containing polymers such as polymaleimide; (meth) acrylic polymers; polyvinylidene fluoride, halogen atom-containing polymers such as polytetrafluoroethylene; ammonium salt-containing polymers; Polymers; natural rubber; conjugated diene polymers; sugars such as hydroxyalkylcellulose (eg, hydroxyethylcellulose); polymers such as amino group-containing polymers such as polyethyleneimine. These binder polymers may be used individually by 1 type, and may be used in combination of 2 or more type.

Among them, aliphatic hydrocarbon group-containing polymers, aromatic hydrocarbon group-containing polymers, and halogen atom-containing polymers are preferred in terms of further increasing the adhesion between the organic layer and the support and exhibiting excellent gas barrier properties. , conjugated diene-based polymers, and (meth) acrylic polymers, preferably at least one selected from the group consisting of aromatic hydrocarbon group-containing polymers, conjugated diene-based polymers, halogen atom-containing polymers, and It is more preferably at least one selected from the group consisting of (meth)acrylic polymers.

Examples of the aliphatic hydrocarbon group-containing polymer include polymers having monomer units derived from aliphatic hydrocarbon group-containing monomers.
The aliphatic hydrocarbon group-containing monomer may be a monomer containing a linear or branched saturated hydrocarbon group or an unsaturated hydrocarbon group, or a monomer containing an alicyclic hydrocarbon group. good.
Preferred examples of the aliphatic hydrocarbon group-containing monomer include olefins such as ethylene, propylene, butene, 1-hexene, 1-heptene and 1-octene.
The aliphatic hydrocarbon group-containing polymer may be a homopolymer composed of one of the aliphatic hydrocarbon group-containing monomers, or may be a copolymer composed of two or more of the aliphatic hydrocarbon group-containing monomers.
As the aliphatic hydrocarbon group-containing polymer, polyolefins such as polyethylene, polypropylene, polybutene and polymethylpentene are preferable, and polyethylene and polypropylene are more preferable.

Examples of the aromatic hydrocarbon group-containing polymer include those having a monomer unit having an aromatic hydrocarbon group such as benzene. Specifically, for example, polyethylene terephthalate, polybutylene terephthalate, polybutylene naphthalate, polystyrene , polysulfone, polyethersulfone, polyphenylene sulfide, polyphenylsulfone, polyarylate, polyetherimide, polyimide, and polyamideimide. Among them, at least one selected from the group consisting of polysulfone, polyethersulfone, and polyphenylsulfone is preferable, and polysulfone is more preferable, in that the gas barrier properties of the diaphragm for electrochemical device can be further enhanced.

Examples of the halogen atom-containing polymer include those having a monomer unit derived from a monomer containing a halogen atom such as a chlorine atom and a fluorine atom. , vinylidene fluoride-hexafluoropropylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, polytetrafluoroethylene, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, polychlorotrifluoroethylene, tetrafluoroethylene- Examples include fluorine-containing polymers such as hexafluoropropylene-vinylidene fluoride copolymers.

The conjugated diene-based polymer is not particularly limited as long as it has a monomer unit derived from a conjugated diene-based monomer, but preferably has a monomer unit derived from an aromatic vinyl monomer.

The conjugated diene-based monomer is preferably an aliphatic conjugated diene-based monomer. Examples of the aliphatic conjugated diene-based monomer include 1,3-butadiene, isoprene, 2-chloro-1,3-butadiene, chloroprene, etc. Among them, 1,3-butadiene is preferred. Conjugated diene-based monomers may be used alone, or two or more of them may be used in combination.

The conjugated diene-based polymer may be a homopolymer such as polybutadiene or polyisoprene, or may be a copolymer. , preferably a copolymer, more preferably a copolymer further having a monomer unit derived from an aromatic vinyl monomer.

Examples of the aromatic vinyl monomer include styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, o-ethylstyrene, m-ethylstyrene, p-ethylstyrene, o-methoxy Styrene, m-methoxystyrene, p-methoxystyrene, o-ethoxystyrene, m-ethoxystyrene, p-ethoxystyrene, o-fluorostyrene, m-fluorostyrene, p-fluorostyrene, o-chlorostyrene, m-chloro Styrene, p-chlorostyrene, o-bromostyrene, m-bromostyrene, p-bromostyrene, o-acetoxystyrene, m-acetoxystyrene, p-acetoxystyrene, o-tert-butoxystyrene, m-tert-butoxystyrene , p-tert-butoxystyrene, o-tert-butylstyrene, m-tert-butylstyrene, p-tert-butylstyrene, vinyltoluene and the like. Among these, styrene and α-methylstyrene are preferable because they can increase the heat resistance and mechanical strength of the membrane for electrochemical devices. These aromatic vinyl monomers may be used alone or in combination of two or more.

In the conjugated diene-based polymer, the mass ratio of the monomer units derived from the aliphatic conjugated diene-based monomer and the monomer units derived from the aromatic vinyl monomer is preferably 1/9 or more, and is 2/8 or more. is more preferable, and 3/7 or more is even more preferable. The mass ratio is preferably 9/1 or less, more preferably 8/2 or less, and even more preferably 7/3 or less.

As the conjugated diene-based polymer, a styrene-butadiene-based copolymer and an acrylonitrile-butadiene-based copolymer are preferable, and a styrene-butadiene-based copolymer is preferable in that the performance of the membrane for an electrochemical device can be further improved. coalescence is more preferred. These copolymers may be modified copolymers such as carboxy-modified.

The conjugated diene-based polymer may have monomer units derived from other unsaturated monomers other than the monomer units derived from the aliphatic conjugated diene-based monomer and the monomer units derived from the aromatic vinyl monomer.

Other unsaturated monomers include acid group-containing vinyl monomers such as itaconic acid, acrylic acid, methacrylic acid, fumaric acid, maleic acid, acrylamidomethylpropanesulfonic acid, and styrenesulfonate; methyl (meth)acrylate; Ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, (meth) acrylic (Meth)acrylate monomers such as hexyl acid, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, and decyl (meth)acrylate; hydroxyl group-containing vinyl monomers such as meth)2-hydroxyethyl acrylate and 4-hydroxybutyl (meth)acrylate, nitrile group-containing vinyl monomers such as (meth)acrylonitrile, (meth)acrylamide, N-methylol(meth)acrylamide, (Meth)acrylamide monomers such as N-ethylol (meth)acrylamide, dimethyl (meth)acrylamide, and diethyl (meth)acrylamide; Functional Vinyl Monomers: Vinyl monomers containing alkoxysilane groups such as 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane and the like can be mentioned. These may be used alone or in combination of two or more.

In 100% by mass of the conjugated diene-based polymer, the mass ratio of monomer units derived from other unsaturated monomers is preferably 40% by mass or less, more preferably 20% by mass or less, and 10% by mass or less. It is more preferable that the content is 5% by mass or less, and it is particularly preferable that the content is 5% by mass or less.

In the present specification, the (meth)acrylic polymer refers to a polymer that does not have a monomer unit derived from a conjugated diene monomer and has structural units derived from a (meth)acrylic monomer. The (meth)acrylic monomer refers to a monomer having an acryloyl group or a methacryloyl group, a group in which a hydrogen atom in these groups is replaced with another atom or atomic group, or a derivative of such a monomer.

The (meth)acrylic polymer is preferably a (meth)acrylic acid polymer. (Meth)acrylic acid-based polymer refers to a polymer having structural units derived from (meth)acrylic acid-based monomers, and (meth)acrylic acid-based monomers are acryloyl groups or methacryloyl groups, or hydrogen atoms in these groups. An atom has a group replaced with another atom or atomic group, and a carboxylic acid group (-COOH group), a carboxylic acid group (-COOM group), or an acid anhydride group thereof (-C (= O) -O-C(=O)- group). M above represents a metal salt, an ammonium salt, or an organic amine salt. Examples of metal atoms forming metal salts include monovalent metal atoms such as alkali metal atoms such as lithium, sodium and potassium; divalent metal atoms such as calcium and magnesium; trivalent metal atoms such as aluminum and iron. Atoms are preferred. Alkanolamines such as ethanolamine, diethanolamine and triethanolamine, and triethylamine are suitable as organic amines that form organic amine salts. The (meth)acrylic acid-based monomer is preferably (meth)acrylic acid (salt). (Meth)acrylic acid (salt) is a monomer having an acryloyl group or a methacryloyl group and a carboxylic acid group (--COOH group) or a carboxylic acid group (--COOM group).

For example, the monomer component for obtaining the (meth)acrylic acid-based polymer preferably contains a (meth)acrylic acid-based monomer and other copolymerizable unsaturated monomers.

In 100% by mass of the (meth)acrylic acid-based polymer, the content of monomer units derived from (meth)acrylic acid-based monomers is 0.1 to 5% by mass, and the content of monomer units derived from other copolymerizable unsaturated monomers The content is preferably 95 to 99.9% by mass. The content of monomer units derived from the (meth)acrylic acid-based monomer is 0.3% by mass or more, and the content of monomer units derived from other copolymerizable unsaturated monomers is 99.7% by mass or less. More preferably, the content of monomer units derived from (meth)acrylic acid-based monomers is 0.5% by mass or more, and the content of monomer units derived from other copolymerizable unsaturated monomers is 99.5% by mass or less. is more preferred. By setting it within such a range, the monomer component is stably copolymerized.

Other copolymerizable unsaturated monomers include (meth)acrylic monomers other than (meth)acrylic acid monomers, unsaturated monomers having aromatic rings, acrylonitrile, trimethylolpropane diallyl ether and other polyfunctional unsaturated monomers. A monomer etc. are mentioned.
The (meth)acrylic monomer other than the (meth)acrylic acid monomer includes, for example, an acryloyl group or a methacryloyl group, or a group in which the hydrogen atom in these groups is replaced with another atom or atomic group. and a monomer having a carboxylic acid ester group or a derivative of such a monomer.

Examples of (meth)acrylic monomers having a carboxylic acid ester group include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, isopropyl acrylate, isopropyl methacrylate, butyl acrylate, butyl methacrylate, and isobutyl acrylate. , isobutyl methacrylate, tert-butyl acrylate, tert-butyl methacrylate, pentyl acrylate, pentyl methacrylate, isoamyl acrylate, isoamyl methacrylate, hexyl acrylate, hexyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, octyl acrylate, octyl methacrylate, isooctyl acrylate, isooctyl methacrylate, nonyl acrylate, nonyl methacrylate, isononyl acrylate, isononyl methacrylate, decyl acrylate, decyl methacrylate, dodecyl acrylate, dodecyl methacrylate, tridecyl acrylate, tridecyl methacrylate, hexadecyl acrylate, hexadecyl methacrylate, octadecyl acrylate, octadecyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, diallyl phthalate, triallyl cyanurate, ethylene glycol diacrylate, ethylene glycol diacrylate Methacrylate, 1,4-butanediol diacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, diethylene glycol diacrylate, diethylene glycol dimethacrylate, allyl acrylate, allyl Methacrylate, etc.; and other esters of (meth)acrylic acid-based monomers, etc., and it is preferable to use one or more of these.

In 100% by mass of the (meth)acrylic acid-based polymer, the content of monomer units derived from (meth)acrylic monomers other than the (meth)acrylic acid-based monomer is preferably 20% by mass or more, and 40% by mass. % or more, more preferably 60 mass % or more. In addition, the content of monomer units derived from (meth)acrylic monomers other than the (meth)acrylic acid monomer is preferably 99.9% by mass or less, more preferably 99.5% by mass or less. preferable.

Examples of the unsaturated monomer having an aromatic ring include divinylbenzene, styrene, α-methylstyrene, vinyltoluene, ethylvinylbenzene and the like, preferably styrene.

In 100% by mass of the (meth)acrylic acid-based polymer, the content of monomer units derived from the unsaturated monomer having the aromatic ring is preferably 1% by mass or more, more preferably 5% by mass or more. , more preferably 10% by mass or more, still more preferably 20% by mass or more, and particularly preferably 40% by mass or more. The content of the monomer units is preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less. In addition, the unsaturated monomer having an aromatic ring may not be used as the monomer component that is the raw material of the (meth)acrylic acid-based polymer.

The binder polymer preferably has a weight average molecular weight of 10,000 or more and 6,500,000 or less. More preferably, the weight average molecular weight is 20,000 or more. The weight average molecular weight can be measured as a polystyrene-equivalent weight average molecular weight by gel permeation chromatography (GPC) under the following conditions.
Apparatus: HCL-8220GPC manufactured by Tosoh Corporation
Column: TSKgel Super AWM-H
Eluent (LiBr.HO, NMP with phosphoric acid): 0.01 mol/L

The binder polymer can be produced, for example, by polymerizing monomer components that form the structural units contained in the polymer described above. Polymerization may be carried out by appropriately selecting from known methods.

The content of the binder polymer is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 7% by mass or more with respect to 100% by mass of the diaphragm for electrochemical elements. . In addition, the content of the binder polymer is preferably 70% by mass or less, more preferably 35% by mass or less, and preferably 30% by mass or less with respect to 100% by mass of the diaphragm for an electrochemical element. More preferred.

(other ingredients)
The organic layer may contain other components in addition to the inorganic compound particles and the binder polymer described above. Other components include, for example, carbon.

The organic layer can be formed using an organic layer-forming material prepared by mixing the above-described inorganic compound particles, binder polymer, and, if necessary, other components with a solvent. The formation of the organic layer will be described in detail in the later-described method for producing a diaphragm for an electrochemical device.

The thickness of the organic layer is preferably 10 to 1000 μm, more preferably 100 to 500 μm, even more preferably 200 to 400 μm.

<Support>
In the present invention, the support is a hydrocarbon-based porous body having hydrophilic functional groups.
The hydrophilic functional group is not particularly limited, and includes a hydroxyl group, a carboxyl group, a sulfonic acid group, a sulfide group, a disulfide group, a fluoro group, a fluorocarbonyl group, a phosphoric acid group, an amino group, an imino group, an amide group, and an alkylene group. Examples include an oxide group and a phenol group. Among them, the hydrophilic functional group includes a hydroxyl group, a carboxylic acid group, a sulfonic acid group, a sulfide group, a fluoro group, and a carbonyl fluoride in terms of forming a hydrogen bond with the inorganic compound particles and the binder polymer in the organic layer. A group such as a phosphate group is preferable, and a hydroxyl group, a carboxylic acid group, a sulfonic acid group, a sulfide group, a fluoro group, and a carbonyl fluoride group are more preferable.

The hydrocarbon-based porous body is a porous body made of a hydrocarbon-based polymer. Examples of the hydrocarbon-based polymer include aliphatic hydrocarbon-based polymers and aromatic hydrocarbon-based polymers. In addition, these polymers have the hydrophilic functional group, and the hydrophilic functional group may be contained in either the main chain or the side chain in the hydrocarbon polymer skeleton.
Examples of the aliphatic hydrocarbon-based polymer include those similar to the aliphatic hydrocarbon group-containing polymer used in the organic layer.
Examples of the aromatic hydrocarbon-based polymer include those similar to the aromatic hydrocarbon group-containing polymer used in the organic layer described above.
Among them, the hydrocarbon-based polymer is preferably at least one selected from the group consisting of polyolefin, polyphenylene sulfide, and polyvinyl alcohol, and polypropylene, polyethylene, and polyphenylene sulfide. At least one selected from the group consisting of is more preferable.

The hydrocarbon-based porous material having a hydrophilic functional group may be composed of a hydrocarbon-based polymer having a hydrophilic functional group, or a hydrocarbon having or not having a hydrophilic functional group. A hydrophilic functional group may be introduced into the porous body.
As a method for introducing the hydrophilic functional group, the hydrocarbon porous material is subjected to a graft polymerization method such as a radiation graft polymerization method; a surface treatment method such as plasma treatment, corona treatment, UV treatment, UV ozone treatment; Treatment method; sulfurous acid gas treatment; oxidation treatment with potassium dichromate solution or potassium permanganate solution; etching treatment with sodium treatment solution; treatment with hydrophilic polymer or surfactant, or coating with textile oil; A well-known method is mentioned. Of these, the sulfurous acid gas treatment method and the fluorine gas treatment method are preferred.

The hydrocarbon-based porous material having hydrophilic functional groups has an oxygen element concentration of 10 atm % or more with respect to 100 atm % of carbon element in the element concentration measured by X-ray photoelectron spectroscopy (ESCA).
When a hydrophilic functional group is introduced into the hydrocarbon-based porous material, the oxygen element concentration increases. In the present invention, when the elemental oxygen concentration of the support is within the range described above, the hydrophilic functional group is introduced in a desired amount, and excellent adhesion between the organic layer and the support is exhibited, resulting in an excellent gas barrier. It can be a diaphragm for an electrochemical device having properties.
More preferably, the oxygen element concentration is 10 to 31 atm %.

Further, in the present invention, when the hydrophilic functional group is introduced into the hydrocarbon-based porous material, it is preferable that at least the sulfur element concentration or the fluorine element concentration increases in addition to the oxygen element concentration.
The hydrocarbon-based porous body having the hydrophilic functional group can exhibit even better adhesion and gas barrier properties. The sulfur element concentration is preferably 0.5 atm % or more, more preferably 0.5 to 20 atm %, based on 100 atm % of the element.
Further, the hydrocarbon-based porous body having the hydrophilic functional group has a fluorine element concentration of 3.5 atm% or more with respect to 100 atm% of the carbon element in the element concentration measured by X-ray photoelectron spectroscopy (ESCA). preferably 3.5 to 12.5 atm %.

The hydrocarbon-based porous body has an oxygen element concentration of 10 atm% or more relative to a carbon element of 100 atm%, and a sulfur element concentration of 0.5 atm%, in element concentrations measured by X-ray photoelectron spectroscopy (ESCA). The aspect described above is one of the more preferred aspects of the present invention.
Further, the hydrocarbon-based porous body has an oxygen element concentration of 10 atm % or more with respect to a carbon element of 100 atm %, and a fluorine element concentration of 3.0 atm %, in element concentrations measured by X-ray photoelectron spectroscopy (ESCA). An aspect of 5 atm % or more is also one of the more preferred aspects of the present invention.
In addition, the hydrocarbon-based porous body has an oxygen element concentration of 10 atm% or more with respect to a carbon element of 100 atm%, and a sulfur element concentration of 0.5 atm%, in element concentrations measured by X-ray photoelectron spectroscopy (ESCA). The aspect described above and having a fluorine element concentration of 3.5 atm % or more is one of the more preferred aspects of the present invention.

The oxygen element concentration, fluorine element concentration, and sulfur element concentration can be measured by X-ray photoelectron spectroscopy (ESCA). : MgKα line) is a value obtained by measurement.

The support is preferably porous and in the form of a sheet.
The form of the support may be appropriately selected according to the purpose and application of the diaphragm for an electrochemical device of the present invention. Examples include mixed fabrics, preferably non-woven fabrics, woven fabrics, or meshes.

The support preferably has a porosity of 10 to 90%. When the porosity is within the above range, the membrane for an electrochemical device can have excellent ion conductivity and gas barrier properties. The porosity is more preferably 20 to 85%, even more preferably 25 to 80%.
The porosity can be determined by immersing the support in deionized water at 20° C. for one day and night and measuring the mass of the support before and after the immersion. Specifically, it can be obtained by the following formula.
Porosity (volume %) = (mass of support after immersion - mass of support before immersion) / density of ion-exchanged water at 20 ° C. / volume of support x 100

The thickness of the support can be appropriately selected according to the purpose and application of the diaphragm for an electrochemical device of the present invention. preferable.

The structure of the diaphragm for an electrochemical device of the present invention is not particularly limited as long as it has the above-described organic layer and a support, and may be appropriately designed according to the purpose and application. The support may be provided on either side of the support, or the organic layer may be provided on both sides of the support.
In the electrochemical device diaphragm of the present invention, it is preferable that at least a part of the support and the organic layer are integrated. By integrating them, the adhesion between the support and the organic layer is excellent, and the gas barrier property of the diaphragm is further improved.

The total thickness of the diaphragm for an electrochemical device of the present invention may be appropriately designed according to the purpose and application, but is generally preferably 10-1000 μm, more preferably 100-500 μm, and even more preferably 200-400 μm.

The porosity of the electrochemical device diaphragm of the present invention is preferably 20 to 80% by volume, more preferably 25 to 75% by volume, and even more preferably 30 to 70% by volume. When the porosity is within the above range, the pores of the diaphragm are continuously filled with the electrolytic solution, so that the membrane can have excellent ion conductivity. In addition, a film having excellent gas barrier properties can be obtained.
The porosity can be determined by immersing the electrochemical diaphragm of the present invention in ion-exchanged water at 20° C. for a whole day and night, and measuring the weight of the diaphragm before and after immersion. Specifically, it can be obtained by the following formula.
Porosity (volume %) = (mass of diaphragm after immersion - mass of diaphragm before immersion) / density of deionized water at 20 ° C. / volume of diaphragm x 100

2. Method for producing a diaphragm for an electrochemical element The method for producing the diaphragm for an electrochemical element of the present invention is not particularly limited, and the organic layer-forming material containing the inorganic compound particles and the binder polymer is rolled on the support. A method of rolling into a film by rolling, a method of rolling into a film by flat press or the like, or a known method of forming into a film such as an injection molding method, an extrusion molding method, or a casting method. can be done. A non-solvent-induced phase separation method is preferably used as a method for efficiently producing a porous membrane for electrochemical devices.

Examples of the method for producing a porous electrochemical device membrane by a non-solvent-induced phase separation method include a method including the following steps (1) and (2).
(1) Step of preparing an organic layer-forming material containing inorganic compound particles and a binder polymer (2) Step of forming an organic layer on a support using the organic layer-forming material method, i.e., a step of preparing an organic layer-forming material containing inorganic compound particles and a binder polymer (hereinafter also referred to as “step (1)”), and using the organic layer-forming material on a support A method for producing a diaphragm for an electrochemical device, which includes a step of forming an organic layer (hereinafter also referred to as "step (2)"), is also one of preferred embodiments of the present invention. Each step will be described below.

Step (1)
In the method for producing a diaphragm for an electrochemical device of the present invention, first, an organic layer-forming material containing the inorganic compound particles and the binder polymer described above is prepared.
A method for preparing the organic layer-forming material is not particularly limited as long as it is a method capable of mixing the inorganic compound particles and the binder polymer, and a known mixing method can be applied.

When the inorganic compound particles and the binder polymer are mixed, the inorganic compound particles, the binder polymer and, if necessary, a solvent may be mixed at the same time, or a dispersion (slurry) in which the inorganic compound particles are dispersed in the solvent is prepared in advance. A binder polymer may be added to and mixed with the dispersion, or a solution may be prepared by dissolving the binder polymer in a solvent, and this solution and the dispersion may be mixed. Among them, in that the inorganic compound particles and the binder polymer can be mixed more uniformly, a dispersion liquid in which the inorganic compound particles are dispersed in a solvent is prepared in advance, and the binder polymer or the binder polymer is added to the dispersion liquid. It is preferable to add and mix a solution in which the binder polymer is dissolved in a solvent.

The mixing method is not particularly limited, and known mixing and dispersing means such as a method using a mixer, ball mill, jet mill, disper, sand mill, roll mill, pot mill, paint shaker, etc. can be applied.

The solvent for dispersing the inorganic compound particles is not particularly limited as long as it has the property of dissolving the binder polymer. Examples include N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, dimethylsulfoxide and the like can be mentioned. These solvents may be used singly or in combination of two or more. Among them, N-methyl-2-pyrrolidone is preferable because the dispersibility of the inorganic compound particles is further improved.

The content of the inorganic compound particles in the dispersion obtained by dispersing the inorganic compound particles in a solvent is preferably 20 to 70% by mass, more preferably 30 to 60% by mass, and 40 to 50% by mass. is more preferable.

The solvent used for the solution in which the binder polymer is dissolved is not particularly limited as long as it has the property of dissolving the binder polymer, and the same solvent as the solvent for dispersing the inorganic compound particles can be mentioned. can be done. These solvents may be used singly or in combination of two or more. Among them, the same solvent as the solvent used for preparing the dispersion liquid is preferable in that the inorganic compound particles and the binder polymer can be mixed and dispersed in a more uniform manner.

The content of the binder polymer in the solution in which the binder polymer is dissolved is preferably 10 to 50% by mass, more preferably 15 to 40% by mass, even more preferably 20 to 30% by mass. .

The dispersion liquid and the binder polymer or the solution in which the binder polymer is dissolved may be appropriately mixed so as to obtain a desired amount according to the purpose and application of the diaphragm for an electrochemical element to be obtained, to prepare the organic layer-forming material.

Step (2)
In the method for producing a diaphragm for an electrochemical device of the present invention, an organic layer is then formed on a support using the organic layer-forming material obtained in step (1).
The method for forming an organic layer on a support using the above organic layer-forming material is not particularly limited. -1) to (2-3) are preferably included.
(2-1) a step of forming a coating film of the organic layer-forming material on a support;
(2-2) a step of solidifying the coating film by contacting the coating film with a non-solvent; and (2-3) a step of obtaining an organic layer by drying the solidified coating film.

Thus, the step of forming the organic layer includes a step of forming a coating film of the organic layer-forming material on a support, a step of contacting the coating film with a non-solvent to solidify the coating film, and An aspect including the step of obtaining an organic layer by drying the solidified coating film is also one of preferred aspects of the method for producing a diaphragm for an electrochemical device of the present invention.

Process (2-1)
Examples of a method for forming a coating film of the organic layer-forming material on a support include a method of applying the organic layer-forming material obtained above onto a substrate, and a method of coating a substrate with the organic layer-forming material. A method of immersing the base material so that the organic layer-forming material adheres to the surface or obtains a base material impregnated with the organic layer-forming material. Among them, the method of applying the above organic layer-forming material onto a support is preferable because a coating film can be easily formed.

The method of applying the resin mixture onto the substrate is not particularly limited, and known application means such as methods using die coating, spin coating, gravure coating, curtain coating, spray, applicator, coater, etc. are applied. be able to.

Further, when producing a diaphragm for an electrochemical element, which is a composite in which an organic layer containing inorganic compound particles and a binder polymer and a support are integrated, the organic layer-forming material is applied onto a substrate, and the coating is performed. The support may be impregnated with the coating liquid by placing the support on the liquid.

The amount of the organic layer-forming material to be applied is not particularly limited, and may be appropriately set so that the thickness of the obtained diaphragm for an electrochemical device is suitable for the purpose and application.

Step (2-2)
The coating is then brought into contact with a non-solvent to solidify the coating.
By bringing the coating film into contact with the non-solvent, the non-solvent diffuses in the coating film and the binder polymer that is not dissolved in the non-solvent is solidified. On the other hand, the solvent in the coating film that is soluble in the non-solvent is eluted from the coating film. The occurrence of such phase separation solidifies the binder polymer to form a porous organic layer.
Examples of the method of bringing the coating film into contact with the non-solvent include a method of immersing the coating film in the non-solvent (coagulation bath).

The non-solvent is not particularly limited as long as it has the property of not substantially dissolving the binder polymer. Examples include ion-exchanged water; lower alcohols such as methanol, ethanol, and propyl alcohol; Among them, ion-exchanged water is preferable from the viewpoint of economy and waste liquid treatment. In addition to the components described above, the non-solvent may contain a small amount of the same solvent as the solvent contained in the coating film.

The amount of the non-solvent used is preferably 50 to 10,000 mass % with respect to 100 mass % of the solid content of the coating film, that is, the organic layer-forming material. More preferably 100 to 5000% by mass, still more preferably 200 to 1000% by mass. In order to adjust the porosity of the membrane for an electrochemical device to be obtained within a preferable range, it is preferable to use the non-solvent in the above ratio.

Step (2-3)
An organic layer is obtained by drying the solidified coating film.
By drying the coating film solidified in the step (2-2) to remove the non-solvent, a diaphragm for an electrochemical device having a porous organic layer formed on a support can be obtained.
The drying method is not particularly limited, and known drying means such as heat drying, hot air drying, and vacuum drying can be used.
The drying temperature is preferably 60 to 80°C.
The drying time is not particularly limited, and may be appropriately designed according to the shape, size, etc. of the diaphragm.

As described above, the diaphragm for an electrochemical device of the present invention can be easily manufactured by the steps (1) and (2) described above.

3. Uses The membrane for electrochemical devices of the present invention has excellent adhesion between the organic layer and the support, and has excellent gas barrier properties. The diaphragm for an electrochemical device of the present invention can exhibit excellent ion permeability and gas barrier properties when applied to, for example, a diaphragm for alkaline water electrolysis. Moreover, when applied to a battery separator, the formation of dendrites can be sufficiently suppressed, and a long cycle life can be exhibited. Thus, the diaphragm for electrochemical devices of the present invention is particularly suitably used as a diaphragm for alkaline water electrolysis and a battery separator.
Preferred embodiments of a diaphragm for alkaline water electrolysis and a battery separator using the diaphragm for an electrochemical device of the present invention are described below.

3-1. Diaphragm for alkaline water electrolysis The diaphragm for an electrochemical device of the present invention can be suitably used as a diaphragm for alkaline water electrolysis. That is, a diaphragm for alkaline water electrolysis comprising an organic layer containing a binder polymer and a support, wherein the organic layer further contains inorganic compound particles, and the support is a hydrocarbon-based organic layer having a hydrophilic functional group. A diaphragm for alkaline water electrolysis characterized by being a porous body is also one of the preferred embodiments of the present invention.

Examples of the inorganic compound particles in the diaphragm for alkaline water electrolysis include those similar to the inorganic compound particles in the above-mentioned "diaphragm for electrochemical element", but among them, the inorganic component is difficult to elute in the alkaline solution. point, magnesium hydroxide, magnesium oxide, zirconium oxide, titanium oxide, or molybdenum oxide is more preferable.

The average particle diameter of the inorganic compound particles is preferably 0.05 to 2.0 μm, more preferably 0.1 to 1.5 μm, in terms of good dispersibility with the binder polymer. More preferably, it is 0.2 to 1.0 μm. The average particle size can be obtained by the same method as the method for measuring the average particle size of the inorganic compound particles in the above-described "separation membrane for electrochemical device".

Examples of the shape of the inorganic compound particles include those similar to those of the inorganic compound particles in the above-mentioned "separation membrane for electrochemical device".

Among the inorganic compound particles described above, one kind may be used alone, or two or more kinds may be used in combination.

The content of the inorganic compound particles in the diaphragm for alkaline water electrolysis is preferably 30 to 90% by mass, more preferably 32 to 85% by mass, and even more preferably 35 to 80% by mass.

As the binder polymer in the diaphragm for alkaline water electrolysis, the same binder polymer as in the above-mentioned "diaphragm for electrochemical element" can be mentioned. , polyethersulfone, and polyphenylsulfone are more preferred.

The content of the binder polymer in the diaphragm for alkaline water electrolysis is preferably 1 to 40% by mass, more preferably 5 to 35% by mass, and even more preferably 7 to 30% by mass.

The diaphragm for alkaline water electrolysis preferably contains 20 to 40 parts by weight, more preferably 22 to 38 parts by weight, and 25 to 35 parts by weight of a binder polymer with respect to 100 parts by weight of the inorganic compound particles. More preferred.

Examples of the support in the diaphragm for alkaline water electrolysis include those similar to the support in the above-mentioned "diaphragm for electrochemical device".
Among them, the material of the support in the diaphragm for alkaline water electrolysis preferably contains at least one resin selected from the group consisting of polypropylene, polyethylene, and polyphenylene sulfide, and is preferably selected from the group consisting of polypropylene and polyethylene. More preferably, it contains at least one selected resin.

The form of the support in the diaphragm for alkaline water electrolysis is preferably a nonwoven fabric, a woven fabric, or a mesh.

The thickness of the support in the diaphragm for alkaline water electrolysis is preferably 30 to 300 μm, more preferably 50 to 250 μm, still more preferably 100 to 200 μm.

In the diaphragm for alkaline water electrolysis, the organic layer may be formed on one surface of the support or may be formed on both surfaces.
In addition, the organic layer and the support are preferably a composite in which at least a part thereof is integrated. By forming the composite, the strength and toughness of the diaphragm for alkaline water electrolysis can be enhanced.

The porosity of the diaphragm for alkaline water electrolysis is preferably 20 to 80% by volume, more preferably 25 to 75% by volume, and still more preferably 30 to 70% by volume. The porosity can be measured by the same method as the method for measuring the porosity in the above-mentioned "diaphragm for electrochemical device".

The thickness of the diaphragm for alkaline water electrolysis is preferably 50 to 1000 μm, more preferably 100 to 500 μm, still more preferably 200 to 400 μm.

As a method for producing the diaphragm for alkaline water electrolysis, the same method as the method for producing the above-described "diaphragm for electrochemical device" can be used. Among them, the non-solvent-induced phase separation method is preferable in that a porous membrane can be efficiently formed.

The diaphragm for alkaline water electrolysis is used as a member of an alkaline water electrolysis device. Examples of the alkaline water electrolysis apparatus include those including an anode, a cathode, and the diaphragm for alkaline water electrolysis arranged between the anode and the cathode. More specifically, the alkaline water electrolysis apparatus has an anode chamber in which an anode exists and a cathode chamber in which a cathode exists, which are separated by the diaphragm for alkaline water electrolysis. Anodes and cathodes include known electrodes including conductive substrates including nickel or nickel alloys, and the like.

The method of electrolyzing water using the alkaline water electrolysis apparatus provided with the diaphragm for alkaline water electrolysis is not particularly limited, and a known method can be used. For example, it can be carried out by filling an electrolytic solution into an alkaline water electrolysis apparatus provided with the diaphragm for alkaline water electrolysis described above and applying an electric current in the electrolytic solution.

As the electrolytic solution, an alkaline aqueous solution in which an electrolyte such as potassium hydroxide or sodium hydroxide is dissolved is used. Although the concentration of the electrolyte in the electrolytic solution is not particularly limited, it is preferably 20 to 40% by mass from the viewpoint of further improving the electrolysis efficiency.

The temperature for electrolysis is preferably 50 to 120° C., more preferably 80 to 90° C., since the ion conductivity of the electrolytic solution can be further improved and the electrolysis efficiency can be further improved. Current application conditions can be performed by known conditions and methods.

3-2. Battery Separator The electrochemical device membrane of the present invention can also be suitably used as a battery separator. That is, a battery separator comprising an organic layer containing a binder polymer and a support, wherein the organic layer further contains inorganic compound particles, and the support is a hydrocarbon-based porous body having a hydrophilic functional group. A battery separator characterized by is also one of the preferred embodiments of the present invention.

Examples of the inorganic compound particles in the battery separator include those similar to the inorganic compound particles in the above-mentioned "separation membrane for electrochemical device". Among them, a hydroxide containing magnesium or a compound containing a hydroxide layer is preferred, and magnesium hydroxide or hydrotalcite is more preferred, in terms of good ionic conductivity.

The average particle size of the inorganic compound particles in the battery separator is preferably 0.001 to 10 μm, more preferably 0.01 to 5 μm, from the viewpoint of good dispersibility with the binder. More preferably 1 to 4 μm. The average particle size can be obtained by the same method as the method for measuring the average particle size of the inorganic compound particles in the above-described "separation membrane for electrochemical device".

The content of the inorganic compound particles in the battery separator is preferably 30 to 99% by mass, more preferably 40 to 95% by mass, and even more preferably 45 to 90% by mass.

As the binder polymer in the battery separator, the same binder polymer as in the above-mentioned "separation membrane for electrochemical device" can be used. Among these, at least one selected from the group consisting of conjugated diene-based polymers, halogen-containing polymers, and (meth)acrylic-based polymers is preferable in terms of extending battery life.

The binder polymer preferably has a glass transition temperature (Tg) of -40°C or higher and 50°C or lower. If the Tg of the binder polymer is less than −40° C., the mechanical strength of the battery separator may be insufficient and the dendrite suppression effect may be reduced. On the other hand, if the Tg exceeds 50° C., the battery separator becomes too hard and brittle, and for example, cracks or the like occur in the battery separator during battery formation, which may reduce the life performance of the battery. In the battery separator of the present invention, in order to suppress the formation of voids caused by the aggregation of the inorganic compound particles, the components contained in the organic layer-forming material are sufficiently kneaded to suppress the aggregation of the inorganic compound particles. However, it is preferable to make the components of the inorganic compound particles and the binder polymer uniform. When the Tg of the binder polymer is −40° C. or higher and 50° C. or lower, the kneaded product when kneaded with the inorganic compound particles has a more moderate fluidity, and the aggregates of the inorganic compound particles are crushed or the organic layer is formed. The components contained in the material can be brought into a more uniform state. The Tg of the binder polymer is more preferably -15°C or higher and 30°C or lower, and still more preferably -10°C or higher and 20°C or lower.
The Tg of the binder polymer was measured by applying the polymer to a glass plate and drying at 120°C for 1 hour to form a polymer film. BRVKER).

The binder polymer content in the battery separator is preferably 1 to 70% by mass, more preferably 5 to 60% by mass.

The battery separator preferably contains 1 to 67 parts by mass, more preferably 2 to 54 parts by mass, and even more preferably 3 to 43 parts by mass of the binder polymer with respect to 100 parts by mass of the inorganic compound particles.

Examples of the support in the battery separator include those similar to the support in the above-mentioned "separation membrane for electrochemical device".
Among them, polyolefin-based, polyphenylene sulfide-based, or polyvinyl alcohol-based materials are preferable as the material of the support in the battery separator.

In the battery separator, the organic layer may be formed on one surface of the support or may be formed on both surfaces. Also, a composite in which the organic layer and the support are integrated may be used.

The thickness of the battery separator is preferably 10 to 1000 μm, more preferably 15 to 800 μm, even more preferably 20 to 500 μm.

Examples of the method for producing the battery separator include the same method as the above-described method for producing the "electrochemical device diaphragm".

The battery separator can be suitably used as a separator for a battery comprising a positive electrode, a negative electrode, and an electrolytic solution.
The positive electrode is not particularly limited as long as it contains an active material normally used as a positive electrode active material for primary batteries and secondary batteries, and known materials can be used.
As the positive electrode active material, for example, oxygen (when oxygen is the positive electrode active material, the positive electrode is a perovskite compound capable of reducing oxygen or oxidizing water, a cobalt-containing compound, an iron-containing compound, a copper-containing compound, a manganese containing compound, vanadium-containing compound, nickel-containing compound, iridium-containing compound, platinum-containing compound; palladium-containing compound; gold-containing compound; silver compound; air electrode composed of carbon-containing compound, etc.); nickel oxyhydroxide, water nickel-containing compounds such as nickel oxide and cobalt-containing nickel hydroxide; manganese-containing compounds such as manganese dioxide; silver oxide; lithium-containing compounds such as lithium cobaltate; iron-containing compounds; be done.

The negative electrode is not particularly limited as long as it contains an active material that is commonly used as a negative electrode active material for primary batteries and secondary batteries, and known materials can be used.
As the negative electrode active material, materials commonly used as negative electrode active materials for batteries, such as materials containing carbon, lithium, sodium, magnesium, zinc, nickel, tin, and silicon, can be used. Among them, a zinc compound is preferable because it can further improve the performance of the separator.

An electrode that constitutes a battery can be manufactured by forming an active material layer on a current collector.
Current collectors that make up the electrodes include (electrolytic) copper foil, copper mesh (expanded metal), foamed copper, punched copper, copper alloys such as brass, brass foil, brass mesh (expanded metal), foamed brass, and punched brass. , nickel foil, corrosion-resistant nickel, nickel mesh (expanded metal), punching nickel, metallic zinc, corrosion-resistant metallic zinc, zinc foil, zinc mesh (expanded metal), (punched) steel plate, non-woven fabric with conductivity; Sn, Pb, Hg, Bi, In, Tl, brass, etc. added (electrolytic) copper foil, copper mesh (expanded metal), foamed copper, perforated copper, copper alloys such as brass, brass foil, brass mesh (expanded metal ), foamed brass, perforated brass, nickel foil, corrosion-resistant nickel, nickel mesh (expanded metal), punched nickel, metallic zinc, corrosion-resistant metallic zinc, zinc foil, zinc mesh (expanded metal), (punched) steel plate, non-woven fabric; Zn, Sn, Pb, Hg, Bi, In, Tl, brass, etc. plated (electrolytic) copper foil, copper mesh (expanded metal), foamed copper, perforated copper, copper alloys such as brass, brass foil, brass mesh (expanded metal), foamed brass, perforated brass, nickel foil, corrosion-resistant nickel, nickel mesh (expanded metal), perforated nickel, metallic zinc, corrosion-resistant metallic zinc, zinc foil, zinc mesh (expanded metal), (punched) steel plate, non-woven fabric silver; materials used as current collectors and containers in alkaline (storage) batteries and air zinc batteries;

The electrolyte that constitutes the battery is not particularly limited as long as it is commonly used as an electrolyte for batteries. The water-containing electrolytic solution refers to an electrolytic solution using only water as an electrolytic solution raw material (aqueous electrolytic solution) or an electrolytic solution using a liquid obtained by adding an organic solvent to water as an electrolytic solution raw material.

An alkaline electrolyte is preferable as the aqueous electrolyte. Examples of alkaline electrolytes include potassium hydroxide aqueous solution, sodium hydroxide aqueous solution, lithium hydroxide aqueous solution, zinc sulfate aqueous solution, zinc nitrate aqueous solution, zinc phosphate aqueous solution, zinc acetate aqueous solution and the like. One or two or more of the aqueous electrolytes may be used.

Moreover, the water-containing electrolytic solution may contain an organic solvent used in an organic solvent-based electrolytic solution. Examples of the organic solvent include ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, γ-butyrolactone, dimethoxymethane, diethoxymethane, dimethoxyethane, tetrahydrofuran, methyltetrahydrofuran, diethoxyethane, dimethylsulfoxide, sulfolane, acetonitrile, Benzonitrile, ionic liquids, fluorine-containing carbonates, fluorine-containing ethers, polyethylene glycols, fluorine-containing polyethylene glycols, and the like. One or two or more of the above organic solvent-based electrolytic solutions can be used. The electrolyte of the organic solvent-based electrolyte is not particularly limited, but LiPF ₆ , LiBF ₄ , LiB(CN) ₄ , lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethylsulfonyl)imide ( LiTFSI) and the like are preferable.

In the case of a water-containing electrolyte containing an organic solvent-based electrolyte, the content of the aqueous electrolyte is preferably 10 to 99.9% by mass with respect to the total 100% by mass of the aqueous electrolyte and the organic solvent-based electrolyte. More preferably, it ranges from 20 to 99.9% by mass.

The form of the battery to which the above battery separator can be applied is a primary battery; a secondary battery (storage battery) that can be charged and discharged; a mechanical charge type battery (a battery that mechanically replaces the zinc negative electrode); (battery composed of a negative electrode, an electrode suitable for charging, and an electrode suitable for discharging), a fuel cell, etc., but a secondary battery or a fuel cell is preferable. .
Although the type of the battery is not particularly limited, batteries using an alkaline electrolyte, such as alkaline dry batteries, silver oxide batteries, manganese-zinc batteries, nickel-zinc batteries, fuel cells, and air batteries, are preferred.

As described above, the electrochemical device diaphragm of the present invention exhibits excellent adhesion between the organic layer and the support, and exhibits excellent gas barrier properties. In addition, it is excellent in long-term cycle life. The diaphragm for an electrochemical device of the present invention is particularly suitable for use as a diaphragm for alkaline water electrolysis and a battery separator.

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited only to these examples. Unless otherwise specified, "part" means "mass part" and "%" means "mass %".

<Example 1>
Magnesium hydroxide (manufactured by Kyowa Chemical Industry Co., Ltd., product number 200-06H, average particle size 0.54 μm) and N-methyl-2-pyrrolidone (manufactured by Wako Pure Chemical Industries, Ltd.) are mixed so that the mass ratio is 1:1, A magnesium hydroxide dispersion was prepared by carrying out dispersion treatment at room temperature for 6 hours using a pot mill containing zirconia media balls.
A polysulfone resin solution is obtained by thermally dissolving a polysulfone resin (manufactured by BASF, product number Ultrason S3010) at a concentration of 30% by mass at 80 to 100°C in N-methyl-2-pyrrolidone (manufactured by Wako Pure Chemical Industries, Ltd.). was prepared.
The magnesium hydroxide dispersion and the polysulfone resin solution obtained above were weighed so that the polysulfone resin (PSU) was 33 parts by mass with respect to 100 parts by mass of magnesium hydroxide. , product number Awatori Mixer ARE-500) at room temperature at 1000 rpm for about 10 minutes. The resulting mixture was filtered through SUS 200 mesh to obtain a coating liquid (organic layer-forming material).
The coating liquid was applied on the PET film with an applicator, and a polypropylene nonwoven fabric treated with fluorine gas and sulfurous acid gas (22.1 atm% oxygen element, 8.3 atm% fluorine element, 8.3 atm% fluorine element, The nonwoven fabric was completely impregnated with the coating liquid by contacting the nonwoven fabric with a sulfur element of 3.3 atm% and a thickness of 160 µm. After that, the nonwoven fabric impregnated with the coating liquid was bathed in water at room temperature for 10 minutes to solidify the coating liquid to form a film, and the film was peeled from the PET film together with the nonwoven fabric in water. After the water bath, the resulting membrane was dried in a dryer at 80°C for 30 minutes to obtain a membrane for an electrochemical device composed of a composite integrated with the nonwoven fabric and the membrane containing magnesium hydroxide and polysulfone resin. . In addition, the total thickness of the obtained diaphragm was 300 μm.

(1. Measurement of bubble point value)
The bubble point value of the diaphragm obtained above was measured using a liquid porometer (manufactured by Porous Materials). Specifically, a diaphragm of 2.5 cmφ was immersed in deionized water at room temperature for 1 hour to be sufficiently wet, and then the diaphragm was filled with Galwick (manufactured by Porous Materials), which is a fluorine-based solvent. The gas pressure against the diaphragm was increased, and the gas pressure at the time when the liquid film of water was broken, Galwick permeated the film, and the weight was observed with a balance was taken as the bubble point value. The bubble point value of the diaphragm was 6.8 bar.

(2. Charge-discharge cycle test of nickel-metal hydride battery)
Nickel hydroxide powder (cobalt-coated product manufactured by Tanaka Chemical Co., Ltd.) and polyvinylidene fluoride (PVDF) resin (KF polymer manufactured by Kureha Co., Ltd.) were mixed at a weight ratio of 95:5 to form a slurry. After being impregnated and dried, it was pressed using a flat plate press to prepare a nickel positive electrode. Similarly, a hydrogen-absorbing alloy powder was used in place of the nickel hydroxide powder to produce a hydrogen negative electrode. The diaphragm obtained above was inserted as a separator between the nickel positive electrode and the hydrogen negative electrode to construct a nickel-metal hydride battery with an electrode size of 2 cm×2 cm. 6M KOH was injected as an electrolytic solution, and a charge/discharge cycle test was performed at a rate of 1C with respect to a theoretical capacity of 75mAh. As a result, the battery could be driven without problems even after 500 cycles.

(3. Charge-discharge cycle test of nickel-zinc battery)
2. above. In the nickel-metal hydride battery of 2. above, except that zinc oxide powder was used in place of the hydrogen-absorbing alloy to form a zinc negative electrode, thereby constructing a nickel-zinc battery. Using the diaphragm obtained above as a separator for an electrochemical device in the same manner as in the nickel-hydrogen battery of No. 1, a charge-discharge cycle test was performed under the same conditions. As a result, a cycle life of 200 cycles was observed.

<Example 2>
As a support, a polypropylene nonwoven fabric obtained by hydrophilizing a nonwoven fabric with fluorine gas and sulfurous acid gas (10.4 atm% oxygen element, 3.9 atm% fluorine element, 0.8 atm% sulfur element, thickness 90 μm with respect to 100 atm% carbon element) A diaphragm for an electrochemical device (total thickness: 300 µm) was produced in the same manner as in Example 1 except that the was used, and was evaluated in the same manner. The resulting diaphragm had a bubble point value of 5.1 bar. A cycle life of 400 cycles was observed in the charge-discharge cycle test of the nickel-zinc battery.

<Example 3>
The same as in Example 1, except that a polyphenylene sulfide nonwoven fabric surface-treated with a textile oil (12.1 atm% oxygen, 12.6 atm% sulfur, 220 μm in thickness with respect to 100 atm% carbon) was used as the support. A diaphragm for an electrochemical device (total thickness: 300 μm) was prepared by the method of No. 2 and evaluated in the same manner. The resulting diaphragm had a bubble point value of 7.2 bar. A cycle life of 220 cycles was observed in the charge-discharge cycle test of the nickel-zinc battery.

<Example 4>
As the support, a polyphenylene sulfide nonwoven fabric surface-treated with a surfactant (29.9 atm% oxygen element, 4.0 atm% sulfur element, 160 μm thick with respect to 100 atm% carbon element) was used as in Example 1. A diaphragm for an electrochemical device (total thickness: 300 μm) was produced in the same manner and evaluated in the same manner. The resulting diaphragm had a bubble point value of 6.5 bar. A cycle life of 190 cycles was observed in the charge-discharge cycle test of the nickel-zinc battery.

<Example 5>
Magnesium hydroxide particles (manufactured by Kyowa Chemical Industry Co., Ltd., product number 200-06H, average particle size 0.54 μm) 100 parts by weight, polyacrylate aqueous solution (40% non-volatile content) 3 parts by weight and ion-exchanged water 42 parts by weight After taking it out and dispersing it for 1 hour using a sand mill, it was filtered to obtain an aqueous dispersion of magnesium hydroxide particles.
After measuring 50 parts by mass of the resulting magnesium hydroxide particle aqueous dispersion and 33 parts by mass of a carboxy-modified styrene-butadiene polymer aqueous dispersion (non-volatile content: 48%, Nalstar SR-152 manufactured by Nippon A&L Co., Ltd.) and mixing , filtration and vacuum defoaming were performed to obtain an organic layer-forming material.
The resulting organic layer-forming material was coated on a polyethylene terephthalate (PET) film with a comma coater so that the weight of the organic layer-forming material when dry was 9.0 mg/cm ² . After contact with a hydrophilic polypropylene nonwoven fabric (20.9 atm% oxygen element, 10.2 atm% fluorine element, 3.9 atm% sulfur element, thickness 160 μm with respect to 100 atm% carbon element), it is dried and removed from the PET film. By peeling off the coating film together with the nonwoven fabric, an electrochemical device membrane in which the nonwoven fabric and the coating film are integrated was obtained. The resulting diaphragm was evaluated in the same manner as in Example 1. The resulting diaphragm had a bubble point value of 8.5 bar. Also, in the charge/discharge cycle test of the nickel-zinc battery, 170 cycle life was observed.

<Example 6>
An aqueous hydrotalcite dispersion was obtained in the same manner as in Example 5, except that hydrotalcite (manufactured by Kyowa Chemical Industry Co., Ltd., product number DHT-6, average particle size 0.20 μm) was used as the inorganic particles. An organic layer was formed using 50 parts by mass of this hydrotalcite aqueous dispersion and 21 parts by mass of a carboxy-modified styrene-butadiene polymer aqueous dispersion (non-volatile content: 48%) prepared in the same manner as in Example 5. A diaphragm for an electrochemical device was obtained in the same manner as in Example 5 except that the materials were obtained. The obtained diaphragm was evaluated in the same manner as in Example 1. The resulting diaphragm had a bubble point value of 7.5 bar. In addition, a cycle life of 220 cycles was observed in the charge-discharge cycle test of the nickel-zinc battery.

<Comparative Example 1>
A diaphragm for an electrochemical element (total thickness: 400 μm) was prepared in the same manner as in Example 1, except that a non-hydrophilized polypropylene nonwoven fabric (1 atm% or less oxygen element relative to 100% carbon element, thickness: 380 μm) was used as the support. got The obtained diaphragm was evaluated in the same manner as in Example 1. The resulting diaphragm had a bubble point value of 0.4 bar. In the charge/discharge cycle test of the nickel-metal hydride battery and the nickel-zinc battery, both had cycle lives of less than 50 cycles.

From the above results, it was confirmed that the diaphragms for electrochemical devices of Examples 1 to 6 had extremely high bubble point values and excellent gas barrier properties as compared with the diaphragm of Comparative Example 1. Further, it was confirmed that the diaphragms for electrochemical devices of Examples 1 to 6 had a very long cycle life and excellent reliability as compared with the diaphragm of Comparative Example 1.

Claims (3)

A diaphragm for an electrochemical device comprising an organic layer containing a binder polymer and a support,
The organic layer further contains inorganic compound particles,
The binder polymer is an aromatic hydrocarbon group-containing polymer,
The organic layer contains 22 parts by mass or more and 67 parts by mass or less of the binder polymer with respect to 100 parts by mass of the inorganic compound particles,
The support is a hydrocarbon-based porous body having a hydrophilic functional group,
The hydrophilic functional group is a hydroxyl group, a carboxyl group, a sulfonic acid group, a carbonyl fluoride group, a phosphoric acid group, an amide group, an alkylene oxide group, or a phenol group,
The hydrocarbon-based porous body comprises at least one hydrocarbon-based polymer selected from the group consisting of polyolefin, polyphenylene sulfide, and polyvinyl alcohol,
The hydrocarbon-based porous body having the hydrophilic functional group is characterized by having an oxygen element concentration of 10 atm % or more with respect to 100 atm % of carbon element in the element concentration measured by X-ray photoelectron spectroscopy (ESCA). Diaphragms for electrochemical devices. The hydrocarbon-based porous material having a hydrophilic functional group further has a sulfur element concentration of 0.5 atm% or more with respect to 100 atm% of carbon element in the element concentration measured by X-ray photoelectron spectroscopy (ESCA). The diaphragm for an electrochemical device according to claim 1. The hydrocarbon-based porous material having a hydrophilic functional group further has a fluorine element concentration of 3.5 atm% or more with respect to 100 atm% of carbon element in the element concentration measured by X-ray photoelectron spectroscopy (ESCA). 3. The diaphragm for an electrochemical device according to claim 1 or 2.