JP2017183088A - Electrode paste composition for air-cee, positive electrode material for air cell and air cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrode paste composition having good dispersibility and excellent coatability, by dispersing a conductive carbon material (A) and/or an oxygen reduction catalyst (B) composing the positive electrode layer of an air-cell, by using a water-soluble resin type dispersant (C).SOLUTION: In an electrode paste composition for air-cell containing a conductive carbon material (A) and/or an oxygen reduction catalyst (B), a water-soluble resin type dispersant (C), and an aqueous liquid medium (D), the water-soluble resin type dispersant (C) is one kind or more of resin selected from a group consisting of a resin having a basic functional group, a resin having an acid functional group, a resin having a basic functional group and an acid functional group, and a nonionic resin.SELECTED DRAWING: None

Description

  The present invention relates to an electrode paste composition for an air battery, a positive electrode material for an air battery, and an air battery.

Currently developed air batteries are energy systems that generate and store electricity by using metal as a negative electrode active material and oxygen in the air as a positive electrode active material. Since the active material on the positive electrode side can use oxygen in the air, it is not necessary to fill the inside of the battery with the positive electrode active material. Therefore, there is a feature that the energy density can be increased as compared with other conventional batteries.
Therefore, for example, zinc-air primary batteries are already widely used as light and high-capacity batteries for hearing aids, and lithium-air secondary batteries are actively researched and developed as on-vehicle batteries that require high capacity batteries. Has been done.

  Since the structure of an air battery varies depending on the type of negative electrode metal, the presence / absence of charging, the operating environment, and the like, the types of members used and the required characteristics vary. However, as for the positive electrode layer that has the function of reducing oxygen in the air, in addition to being a common member regardless of the primary battery and secondary battery, the voltage and capacity of the battery greatly depend on the material, so active research Has been.

  Various measures have been taken so far to improve output by improving the positive electrode layer. For example, the use of a positive electrode material in which carbon nanotubes are doped with N (Patent Document 1), the positive electrode layer has a laminated structure of a catalyst layer and a liquid-tight ventilation layer, and the catalyst layer has hydrophilic particles in addition to carbon particles and catalyst particles. There have been reports of the use of a porous layer containing Pt (Patent Document 2). However, in these reports, the material type used for the positive electrode material is not sufficiently dispersed, and carbon materials are particularly prone to agglomeration, so that a conduction path is formed throughout the positive electrode layer and oxygen molecules are diffused throughout the film. Has been hindered, causing a decrease in electromotive force and current amount. In addition, it has been reported that a mixture of polyvinyl alcohol and activated carbon is sprayed to improve adhesion to the positive electrode reaction surface (Patent Document 3). However, in this report, only activated carbon with low conductivity is used in the film, so that the resistance of the film is high and a sufficient electron conduction path necessary for the positive electrode reaction cannot be secured, and the molecular weight of polyvinyl alcohol is about 600. The dispersion effect due to steric hindrance and the like is low, so that it is difficult to stabilize the dispersion of the activated carbon, resulting in a non-uniform film and high battery performance.

Japanese Patent Laying-Open No. 2015-220036 Japanese Patent Application Laid-Open No. 2015-79579 Japanese Patent Laid-Open No. 10-326631

  The problem to be solved by the present invention is to disperse the conductive carbon material (A) and / or the oxygen reduction catalyst (B) constituting the positive electrode layer of the air battery using the water-soluble resin type dispersant (C). By preparing an electrode paste composition for an air battery, an electrode paste composition having good dispersibility and excellent coating properties is provided. Further, by using the electrode paste composition of the present invention, a positive electrode material for an air battery that has very little electrode coating unevenness and pinholes when applied, and an air battery having the battery performance having the same Is to provide.

As a result of intensive studies to solve the above problems, the present inventors have reached the present invention.
That is, the present invention provides an electrode for an air battery comprising a conductive carbon material (A) and / or an oxygen reduction catalyst (B), a water-soluble resin type dispersant (C), and an aqueous liquid medium (D). A paste composition comprising:
The water-soluble resin type dispersant (C) is one or more selected from the group consisting of a resin having a basic functional group, a resin having an acidic functional group, a resin having a basic functional group and an acidic functional group, and a nonionic resin. It is related with the electrode paste composition for air batteries which is resin.
Moreover, this invention relates to the said electrode paste composition for air batteries whose water-soluble resin type dispersing agent (C) is polyvinyl resin.

  Moreover, this invention relates to the said electrode paste composition for air batteries whose water-soluble resin type dispersing agent (C) is nonionic resin.

  The present invention also relates to the above electrode paste composition for an air battery, wherein the conductive carbon material (A) is one or more carbon materials selected from the group consisting of carbon black, graphene-based carbon materials, and carbon nanotubes.

  The present invention also provides the above electrode paste composition for an air battery, wherein the oxygen reduction catalyst (B) is one or more oxygen reduction catalysts selected from the group consisting of a supported metal catalyst, an oxide catalyst and a non-platinum carbon catalyst. About.

  Moreover, this invention relates to the said electrode paste composition for air batteries which further contains a binder.

  Moreover, this invention relates to the said electrode paste composition for air batteries which contains a supporting electrolyte salt further.

  Moreover, this invention relates to the positive electrode material for air batteries formed using the said composition.

  Moreover, this invention relates to the air battery formed using the said composition or the said positive electrode material.

  According to the present invention, the conductive carbon material (A) and / or the oxygen reduction catalyst (B) constituting the positive electrode layer of the air battery is dispersed using the water-soluble resin type dispersant (C), and the air battery is used. By preparing an electrode paste composition, it is possible to provide an electrode paste composition that has good dispersibility and excellent coating properties. It is possible to obtain a positive electrode material for an air battery with very few pinholes and an air battery having the material. Therefore, it is possible to provide an air battery having excellent battery performance.

  Hereinafter, the present invention will be described in detail. In the present specification, the “electrode paste composition for an air battery” may be referred to as an “electrode paste composition” or a “paste composition”. Further, “resin” is sometimes referred to as “polymer”.

<Air electrode electrode paste composition>
The electrode paste composition of the present invention includes a conductive carbon material (A) and / or an oxygen reduction catalyst (B), a water-soluble resin type dispersant (C), and an aqueous liquid medium (D), and further includes a binder. Depending on the case, a supporting electrolyte salt is included.
The proportions of the conductive carbon material (A) and / or the oxygen reduction catalyst (B), the water-soluble resin dispersant (C), the aqueous liquid medium (D), the binder, and the supporting electrolyte salt are not particularly limited. And can be appropriately selected within a wide range.

  The content of the water-soluble resin type dispersant (C) is 0.1 to 40% by mass, preferably 1 with respect to the conductive carbon material (A) and / or the oxygen reduction catalyst (B) in the electrode paste composition. ˜5 mass%. By setting the content in this range, the dispersion stability of the conductive carbon material (A) and / or the oxygen reduction catalyst (B) can be sufficiently achieved, and at the same time, the conductive carbon material (A) and / or oxygen reduction. Aggregation of the catalyst (B) can be effectively prevented, and precipitation of the water-soluble resin type dispersant (C) on the film surface can be prevented even after the electrode paste composition is applied and dried.

  The water-soluble liquid medium (D) is 60 to 99 parts by mass, preferably 65 to 95% by mass, when the electrode paste composition is 100% by mass.

Such an electrode paste composition can be obtained by various methods.
Taking the case of an electrode paste composition containing a conductive carbon material (A) and / or an oxygen reduction catalyst (B), a water-soluble resin dispersant (C), a binder and an aqueous liquid medium (D) as an example explain.
For example,
(X-1) Conductive carbon material (A) containing conductive carbon material (A) and / or oxygen reduction catalyst (B), water-soluble resin type dispersant (C), and aqueous liquid medium (D) and An aqueous dispersion of the oxygen reduction catalyst (B) can be obtained, and a binder can be added to the aqueous dispersion to obtain an electrode paste composition.
(X-2) Conductive carbon material (A) and / or oxygen reduction catalyst (B), water-soluble resin type dispersant (C), binder and aqueous liquid medium (D) containing conductive carbon material (A) And / or the aqueous dispersion of an oxygen reduction catalyst (B) can be obtained, and an electrode paste composition can be obtained.
(X-3) A solution containing the water-soluble resin type dispersant (C), the binder, and the aqueous liquid medium (D) is obtained, and the conductive carbon material (A) and / or the oxygen reduction catalyst (B) is further added. An electrode paste composition can be obtained.

<Conductive carbon material (A)>
The conductive carbon material (A) in the present invention is not particularly limited as long as it is a carbon material that has conductivity and does not have the oxygen reduction activity in the present invention. , Conductive carbon fibers (carbon nanotubes, carbon nanofibers, carbon fibers), fullerenes and the like can be used alone or in combination of two or more. From the viewpoint of conductivity, availability, and cost, it is preferable to use carbon black.

  Carbon black is a furnace black produced by continuously pyrolyzing a gas or liquid raw material in a reactor, especially ketjen black using ethylene heavy oil as a raw material. Channel black that has been rapidly cooled and precipitated, thermal black obtained by periodically repeating combustion and thermal decomposition using gas as a raw material, and particularly various types such as acetylene black using acetylene gas as a raw material, or 2 More than one type can be used in combination. Ordinarily oxidized carbon black, hollow carbon and the like can also be used.

  The oxidation treatment of carbon is performed by treating carbon at a high temperature in the air or by secondary treatment with nitric acid, nitrogen dioxide, ozone, etc., for example, such as phenol group, quinone group, carboxyl group, carbonyl group. This is a treatment for directly introducing (covalently bonding) an oxygen-containing polar functional group to the carbon surface, and is generally performed to improve the dispersibility of carbon. However, since it is common for the conductivity of carbon to fall, so that the introduction amount of a functional group increases, it is preferable to use the carbon which has not been oxidized.

As the specific surface area of the carbon black used increases, the number of contact points between the carbon black particles increases, which is advantageous in reducing the internal resistance of the electrode. Specifically, the specific surface area (BET) determined from the amount of nitrogen adsorbed is 20 m ² / g or more and 1500 m ² / g or less, preferably 50 m ² / g or more and 1500 m ² / g or less, more preferably 100 m ^2. / G or more,
It is desirable to use a thing of 1500 m < ² > / g or less. If carbon black having a specific surface area of less than 20 m ² / g is used, it may be difficult to obtain sufficient conductivity, and carbon black of more than 1500 m ² / g may be difficult to obtain from commercially available materials. is there.

  Further, the particle size of the carbon black to be used is preferably 0.005 to 1 μm, particularly preferably 0.01 to 0.2 μm in terms of primary particle size. However, the primary particle diameter here is an average of the particle diameters measured with an electron microscope or the like.

The dispersed particle size of the conductive carbon material (A) in the electrode paste composition is desirably refined to 0.03 μm or more and 5 μm or less. A composition having a carbon material having a dispersed particle size of less than 0.03 μm may be difficult to produce. In addition, when a composition having a dispersed particle diameter of the carbon material exceeding 5 μm is used, problems such as variations in the material distribution of the electrode paste coating film and variations in the resistance distribution may occur.
The dispersed particle size referred to here is a particle size (D50) that is 50% when the volume ratio of the particles is integrated from the fine particle size distribution in the volume particle size distribution. A particle size distribution meter such as a dynamic light scattering type particle size distribution meter ("Microtrack UPA" manufactured by Nikkiso Co., Ltd.).

Examples of commercially available carbon black include Toka Black # 4300, # 4400, # 4500, # 5500 (Tokai Carbon Co., Furnace Black), Printex L and the like (Degussa Co., Furnace Black), Raven 7000, 5750, 5250, 5000 ULTRA III, 5000 ULTRA, etc., Conductex SC ULTRA
, Conductex 975 ULTRA, etc., PUER BLACK100, 115, 2
05, etc. (Colombian, Furnace Black), # 2350, # 2400B, # 2600B, # 3050B, # 3030B, # 3230B, # 3350B, # 3400B, # 5400B, etc. (Mitsubishi Chemical Corporation, Furnace Black), MONARCH1400, 1300, 900, Vulcan XC-72R, BlackPearls 2000, etc. (Cabot, Furnace Black), Ensaco 250G, Ensaco 260G, Ensaco 350G, SuperP-Li (manufactured by TIMCAL), Ketjen Black EC-300J, EC-600JD (manufactured by Akzo) Examples of graphite such as Denka Black, Denka Black HS-100, FX-35 (manufactured by Denki Kagaku Kogyo Co., Ltd., acetylene black) include artificial graphite and flake black , Massive graphite, there may be mentioned natural graphite such as earthy graphite, is not limited thereto, it may be used in combination of two or more.

  As the conductive carbon fibers, those obtained by firing from petroleum-derived raw materials are preferable, but those obtained by firing from plant-derived raw materials can also be used. For example, VGCF manufactured by Showa Denko Co., Ltd. manufactured with petroleum-derived raw materials can be mentioned.

<Oxygen reduction catalyst (B)>
The oxygen reduction catalyst (B) in the present invention is not particularly limited as long as it has the oxygen reduction activity referred to in the present invention, but is not limited to a supported metal catalyst, an oxide catalyst, a non-platinum carbon catalyst. , Can be used alone or in combination of two or more.
Oxygen reduction catalysts differ greatly in physical properties such as oxygen reduction ability, conductivity, specific surface area, pore volume, pore diameter, surface hydrophilicity, particle diameter, etc. Selected.

The term “having oxygen reduction activity” as used in the present invention means that it has a function of electrochemically reducing oxygen molecules in a gaseous state or a dissolved state in a liquid, and in an acidic aqueous solution saturated with oxygen. When the linear sweep voltammetry by the rotating disk electrode method is measured, it means that the oxygen reduction reaction potential (ORR potential) is 0.5 V (vsRHE; reversible hydrogen electrode) or more. The ORR potential was a potential at a rotation speed of 2000 rpm and a current density of −10 μA / cm ² in an acidic aqueous solution saturated with oxygen. The ORR potential means that the higher the voltage, the easier the adsorption and dissociation of oxygen molecules on the oxygen reduction catalyst (B), and the activation energy required for the reaction can be lowered. Loss can be reduced. Therefore, it may be preferable to use not only the conductive carbon material (A) but also the oxygen reduction catalyst (B) for the positive electrode material for the air battery.

  The oxygen reduction catalyst (B) is not particularly limited, but a supported metal catalyst, an oxide catalyst, and a non-platinum carbon catalyst are preferable. Oxygen reduction catalysts differ greatly in physical properties such as oxygen reduction ability, conductivity, specific surface area, pore volume, pore diameter, surface hydrophilicity, particle diameter, etc. Selected.

  As the supported metal catalyst, noble metal elements such as platinum and other base metal elements are used as the catalyst metal. From the viewpoint of high catalytic action, noble metals such as platinum, palladium, rhodium, and gold are preferable, and nanoparticles and alloys may be used in order to increase the effective specific surface area. As the carrier, a material such as a carbon material, an oxide, or a polymer can be used. However, in consideration of the function as an electrode, it may be preferable to use a conductive carbon material.

  As the oxide catalyst, oxide particles containing a transition metal and an oxygen element as main components, and conventionally known ones can be used. Crystal structure and shape of oxide particles, control of particle size, introduction of oxygen defects, doping of different elements such as nitrogen, and fine particle size improve catalyst properties such as oxygen adsorption capacity and electron conductivity. It is effective for producing high oxygen reducing ability. The element constituting the oxide is at least one transition metal selected from the group consisting of Zr, Ta, Ti, Nb, V, Fe, Mn, Co, Ni, Cu, Zn, Cr, W, and Mo. It is preferable to use an oxide containing.

A non-platinum-based carbon catalyst (hereinafter also referred to as a carbon-based catalyst material or CAC) is composed of a multi-component system mainly composed of aggregates of carbon (C) atoms. A catalytic material that has an interaction (bonding) and contains a heterogeneous element such as a heteroatom such as N, B, or P, or a base metal element, and has one or more kinds of carbon material, nitrogen element, and base metal element. The compound can be obtained by mixing and heat treatment, and conventionally known compounds can be used. Base metal elements here are metal elements excluding noble metal elements (ruthenium, rhodium, palladium, silver, osmium, iridium, platinum, gold) among transition metal elements, and base metal elements include cobalt, iron, nickel, It is preferable to contain one or more selected from manganese, copper, titanium, vanadium, chromium, zinc, tin, aluminum, and magnesium.
The inclusion of a heteroatom and a base metal element is important for having oxygen reduction activity. In general, in the case of a carbon-based catalyst material, as a catalytic active point, for example, a base metal in a structure (called a base metal-N4 structure) in which four nitrogen atoms are arranged on a plane centering on a base metal element on the surface of the carbon material. Examples include elements and carbon atoms in the vicinity of heteroatoms introduced into the edge of the carbon material surface.

  When the oxygen reduction catalyst (B) itself does not exhibit conductivity, it may be preferable to use it together with the conductive carbon material (A).

<Water-soluble resin type dispersant (C)>
The water-soluble resin type dispersant (C) used in the present invention effectively functions as a dispersant for the conductive carbon material (A) and / or the oxygen reduction catalyst (B), and can reduce the aggregation. it can. The water-soluble resin type dispersant (C) is not particularly limited as long as it has an effect of relaxing aggregation with respect to the conductive carbon material (A) and / or the oxygen reduction catalyst (B). In view of the dispersibility and coating suitability of the carbon material (A) and / or the oxygen reduction catalyst (B), a polyvinyl resin is preferable, and a nonionic resin is more preferable.

  The polyvinyl resin in the present invention is a general term for resins obtained by polymerizing a polymerizable monomer having a vinyl group, which will be described later.

The resin having a basic functional group includes a cyclic amino group, a partially or completely neutralized skeleton and a quaternary ammonium salt,
Homopolymers of polymerizable monomers such as dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, methylethylaminoethyl (meth) acrylate, dimethylaminostyrene, diethylaminostyrene, or other polymerizable monomers And their acid neutralized products.

The resin having an acidic functional group contains a carboxyl group, a sulfo group, a phosphoric acid group and a skeleton obtained by neutralizing part or all of them,
Polymerizable monomers having a carboxyl group such as maleic acid, fumaric acid, itaconic acid, citraconic acid, acrylic acid, methacrylic acid, crotonic acid, cinnamic acid,
Sulfos such as vinyl sulfonic acid, (meth) allyl sulfonic acid, styrene sulfonic acid, (meth) acryloyloxyethyl sulfonic acid, isoprene sulfonic acid, 2- (meth) acrylamido-2-methylpropane sulfonic acid, allyloxybenzene sulfonic acid A polymerizable monomer having a group,
Mono (2-acryloyloxyethyl) acid phosphate, mono (2-methacryloyloxyethyl) acid phosphate, diphenyl (2-acryloyloxyethyl) phosphate, diphenyl (2-methacryloyloxyethyl) phosphate, phenyl (2-acryloyloxyethyl) Phosphate, acid phosphooxyethyl methacrylate, methacryloyl oxyethyl acid phosphate monoethanolamine salt, 3-chloro-2-acid phosphooxypropyl methacrylate, acid phosphooxypolyoxyethylene glycol monomethacrylate, acid phosphooxypoly Oxypropylene glycol methacrylate, (meth) acryloyloxyethyl acid phosphate, (meth) acrylate Liloyloxypropyl acid phosphate, (meth) acryloyloxy-2-hydroxypropyl acid phosphate, (meth) acryloyloxy-3-hydroxypropyl acid phosphate, (meth) acryloyloxy-3-chloro-2-hydroxypropyl acid phosphate, Examples include homopolymers of polymerizable monomers having a phosphate group such as allyl alcohol acid phosphate, copolymers with other polymerizable monomers, and alkali neutralized products thereof.

  The resin having a basic functional group and an acidic functional group means a resin containing both the basic skeleton and the acidic skeleton, and is a copolymer of styrene-maleic acid-N, N-dimethylaminoethyl (meth) acrylate. Such as things.

  Nonionic resin is a water-soluble resin other than the resin having the basic functional group, the resin having an acidic functional group, the resin having the basic functional group and the acidic functional group, and includes polyvinyl pyrrolidone, polyvinyl alcohol, polyacrylamide, -N-vinylacetamide, polyalkylene glycol, etc. are mentioned.

  The nonionic resin may be a copolymer composed of a plurality of polymerizable monomers exemplified below.

  Examples of the polymerizable monomer having an aromatic ring include styrene, α-methylstyrene, and benzyl (meth) acrylate.

Specific examples of the polymerizable monomer having a chain saturated hydrocarbon group include 1 carbon atom such as methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and butyl (meth) acrylate. There are ˜22 alkyl (meth) acrylates, preferably an alkyl group-containing acrylate having a C 2-12 alkyl group, more preferably a C 2-8 alkyl group, or a corresponding methacrylate. These alkyl groups may be branched, and specific examples include isopropyl (meth) acrylate, isobutyl (meth) acrylate, tertiary butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, 2-butylhexyl (meth) ) Acrylate and the like.
Moreover, fatty acid vinyl compounds such as vinyl acetate, vinyl butyrate, vinyl propionate, vinyl hexanoate, vinyl caprylate, vinyl laurate, vinyl palmitate, vinyl stearate and the like can be mentioned.
Furthermore, α-olefin compounds such as 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene and the like can be mentioned.

  Examples of polymerizable monomers having a cyclic saturated hydrocarbon group include isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, cyclohexyl (meth) acrylate, trimethylcyclohexyl (meth) acrylate, and 1-adamantyl (meth) acrylate. Etc.

Examples of the polymerizable monomer having a polyoxyalkylene structure include diethylene glycol mono (meth) acrylate, polyethylene glycol mono (meth) acrylate, and polypropylene glycol mono (meth) acrylate, which have a hydroxyl group at the terminal and have a polyoxyalkylene chain. Having mono- or monomethacrylate, methoxyethylene glycol (meth) acrylate, methoxydiethylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, methoxypolypropylene glycol (meth) acrylate, etc. There are monoacrylates with oxyalkylene chains or the corresponding monomethacrylates. Examples of the alkyl vinyl ether compound include butyl vinyl ether and ethyl vinyl ether.
Further, a cyclic compound such as glycidyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, or the like may be used.

Examples of the polymerizable monomer having a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, glycerol mono (meth) acrylate, 4-hydroxystyrene, Examples include vinyl alcohol and allyl alcohol.
Examples of the polymerizable monomer that is a derivative of vinyl alcohol include vinyl esters such as vinyl acetate, vinyl propionate, and vinyl versatate. A hydroxyl group can be formed by copolymerizing these vinyl esters and saponifying the obtained copolymer with sodium hydroxide or the like.

  Examples of nitrogen-containing polymerizable monomers include monoalkyls such as N-vinyl-2-pyrrolidone, (meth) acrylamide, N-vinylacetamide, N-methylol (meth) acrylamide, and N-methoxymethyl- (meth) acrylamide. Examples thereof include roll (meth) acrylamide, N, N-di (methylol) acrylamide, N-methylol-N-methoxymethyl (meth) acrylamide, N, N-di (methoxymethyl) acrylamide and the like.

Furthermore, as other monomers, perfluoromethylmethyl (meth) acrylate, perfluoroethylmethyl (meth) acrylate, 2-perfluorobutylethyl (meth) acrylate, 2-perfluorohexylethyl (meth) acrylate, etc. Perfluoroalkyl alkyl (meth) acrylates having a C 1-20 perfluoroalkyl group;
Perfluoroalkyl such as perfluorobutylethylene, perfluorohexylethylene, perfluorooctylethylene, perfluorodecylethylene, and perfluoroalkyl group-containing vinyl monomers such as alkylene, vinyltrichlorosilane, vinyltris (βmethoxyethoxy) silane, vinyl Examples thereof include silanol group-containing vinyl compounds such as triethoxysilane and γ- (meth) acryloxypropyltrimethoxysilane and derivatives thereof, and a plurality of them can be used from these groups.

  Examples of the ethynyl compound include acetylene, ethynylbenzene, ethynyltoluene, 1-ethynyl-1-cyclohexanol and the like. These can be used alone or in combination of two or more.

  The water-soluble resin type dispersant (C) is not limited to the above-described polyvinyl resins, but also polyurethane resins, polyester resins, polyether resins, carboxymethyl cellulose and other cellulose resins, formalin condensates, silicone resins, and composites thereof. Examples thereof include polymers. Furthermore, two or more of these water-soluble resin type dispersants (C) may be used in combination.

  Examples of commercially available water-soluble resin type dispersants (C) include Disperbyk-180, 183, 184, 185, 187, 190, 191, 192, 193, 194, 198, 199, 2010, 2012, 2015, 2090, 2091, 2095, 2096, etc. (manufactured by Big Chemie), SOLSPERSE 20000, 27000, 40000, 41090, 44000, 46000, 47000, 64000, 65000, 66000, etc. (manufactured by Nihon Lubrizol), Floren G-700AMP, G-700DMEA, WK -13E, GW-1500, GW-1640, etc. (manufactured by Kyoeisha Chemical Co., Ltd.), Borchi® Gen 1350, 0851, 1253, SN95, WNS, etc. (manufactured by Matsuo Sangyo Co., Ltd.), TEGO Dispers 650, 651, 652, 655, 660C, 715W, 740W, 750W, 752W, 755W, 760W, etc. (manufactured by Sakai Kogyo Co., Ltd.), polyvinylpyrrolidone PVP-K30, K85, K90, etc. (manufactured by ISP Japan), ESREC BL-1, BL-2, BL -5, BL-10, BL-1H, BL-2H, BL-S, BM-S, BM-1, BM-2, BM-5, BH-A, BX-1, BX-3, BX-5 Etc. (manufactured by Sekisui Chemical Co., Ltd.), carboxymethyl cellulose CMC1105, 1110, 1130, 1140, 1170, 1190, 1205, 1210, 1240, 1250, etc. (manufactured by Daicel Chemical Industries, Ltd.), but are not limited thereto. .

  In addition, the mass average molecular weight of the water-soluble resin type dispersant (C) is 3000 or more and less than 500000 from the viewpoint of good dispersibility of the conductive carbon material (A) and / or the oxygen reduction catalyst (B). Preferably it is 5000 or more and less than 400,000.

<Aqueous liquid medium (D)>
As the aqueous liquid medium used in the present invention, it is preferable to use water, but if necessary, for example, a liquid medium compatible with water is used to improve the coating property to the conductive support. You may do it.
Liquid media compatible with water include alcohols, glycols, cellosolves, amino alcohols, amines, ketones, carboxylic acid amides, phosphoric acid amides, sulfoxides, carboxylic acid esters, and phosphoric acid esters , Ethers, nitriles and the like, and may be used as long as they are compatible with water. As the alcohol, for example, a monohydric alcohol or a polyhydric alcohol having a boiling point of about 80 to 200 ° C. can be used, and preferably an alcohol solvent having 4 or less carbon atoms. Specific examples include 1-propanol, 2-propanol, 1-butanol, 2-butanol, and t-butanol. Among these monohydric alcohols, 2-propanol, 1-butanol and t-butanol are preferable. Specific examples of the polyhydric alcohol include propylene glycol and ethylene glycol, and propylene glycol is particularly preferable.

<Binder>
The binder in the present invention is used for binding particles such as the conductive carbon material (A) and / or the oxygen reduction catalyst (B), and the effect of dispersing the particles in the solvent is small. Is.
As the binder, conventionally known binders can be used. For example, acrylic resin, polyurethane resin, polyester resin, phenol resin, epoxy resin, phenoxy resin, urea resin, melamine resin, alkyd resin, formaldehyde resin, silicon resin, Examples thereof include fluorine resins, synthetic rubbers such as styrene-butadiene rubber and fluorine rubber, conductive resins such as polyaniline and polyacetylene, and polymer compounds containing fluorine atoms such as polyvinylidene fluoride, polyvinyl fluoride, and tetrafluoroethylene. Further, a modified product, a mixture, or a copolymer of these resins may be used, which may be a water-soluble resin or a water-dispersed resin. These binders can be used alone or in combination.

  Moreover, when using an aqueous liquid medium (D), the binder generally called an aqueous emulsion can also be used. The aqueous emulsion is one in which the binder resin is dispersed in the form of fine particles without being dissolved in water.

  The emulsion to be used is not particularly limited, and examples thereof include (meth) acrylic emulsions, nitrile emulsions, urethane emulsions, diene emulsions (such as SBR), and fluorine emulsions (such as PVDF and PTFE).

<Disperser / Mixer>
As an apparatus used when obtaining the electrode paste composition of the present invention, a disperser or a mixer that is usually used for pigment dispersion or the like can be used.

  For example, mixers such as dispersers, homomixers, or planetary mixers; homogenizers such as “Clairemix” manufactured by M Technique, or “Fillmix” manufactured by PRIMIX; paint shaker (manufactured by Red Devil), ball mill, sand mill (Shinmaru Enterprises "Dynomill", etc.), Attritor, Pearl Mill (Eirich "DCP Mill", etc.), or Coball Mill, etc .; Media type dispersers; Wet Jet Mill (Genus, "Genus PY", Sugino Media-less dispersers such as “Starburst” manufactured by Machine, “Nanomizer” manufactured by Nanomizer, etc., “Claire SS-5” manufactured by M Technique, or “MICROS” manufactured by Nara Machinery; or other roll mills, etc. These are mentioned The present invention is not limited. Moreover, as the disperser, it is preferable to use a disperser that has been subjected to a metal contamination prevention treatment from the disperser.

  For example, when using a media-type disperser, a disperser in which the agitator and vessel are made of a ceramic or resin disperser, or the surface of the metal agitator and vessel is treated with tungsten carbide spraying or resin coating. Is preferably used. As the media, it is preferable to use glass beads, ceramic beads such as zirconia beads or alumina beads. Moreover, also when using a roll mill, it is preferable to use a ceramic roll. Only one type of dispersion device may be used, or a plurality of types of devices may be used in combination.

<Positive electrode layer for air battery>
The positive electrode layer for an air battery is formed by directly applying the electrode paste composition onto a conductive support (such as carbon paper) and drying it.
The method for applying the electrode paste composition is not particularly limited, and examples thereof include a knife coater, a bar coater, a blade coater, a spray, a dip coater, a spin coater, a roll coater, a die coater, a curtain coater, and screen printing. General methods can be applied.

  A coating film (catalyst layer for an air battery) is formed by drying after coating. A drying temperature is about 40-200 degreeC normally, Preferably it is about 70-120 degreeC. The drying time is usually about 5 minutes to 2 hours, preferably about 30 minutes to 1 hour, although it depends on the drying temperature.

<Conductive support>
The conductive support is not particularly limited, but in a metal-air battery, a porous or fibrous support that allows gas to pass and diffuse so that oxygen in the air can be taken in on the positive electrode side is preferable. In addition, since electrons need to be taken in and out, a conductive material must be used. Carbon paper made of carbon material, carbon felt, carbon cloth, etc. are preferable. Specific examples include “TGP-H-090” manufactured by Toray Industries, Inc. These conductive supports are also called gas diffusion layers or GDLs.

<Metal-air battery>
A metal-air battery uses a metal as a negative electrode active material, and can generate electric power by using an oxygen reduction reaction on the positive electrode side by the generated e ⁻ (electrons) and metal ions. Also works.
The configuration of the metal-air battery includes a negative electrode having a metal as a negative electrode active material, a conductive support serving as a positive electrode coated with an electrode paste composition for an air battery, and conduction of metal ions between the positive electrode and the negative electrode. It consists of an electrolyte layer and a separator.
As a positive electrode, the electrode paste composition for air batteries in this invention can be used conveniently.

<Negative electrode material>
As the negative electrode, a metal material made of a single metal or an alloy can be used. Examples of the metal material that can be used as the negative electrode include Li, Na, Mg, Al, Si, Ca, Ti, V, Cr, Mn, Fe, and the like, and these metal carriers and alloys are applied. You can also. However, the material is not limited to these, and a conventionally known material applied to an air battery can be used.

<Electrolyte layer>
The electrolyte layer conducts metal ions between the positive electrode and the negative electrode of the metal-air battery. The type of metal ion varies depending on the type of the negative electrode active material described above, and the form thereof is not particularly limited as long as it has metal ion conductivity. For example, an aqueous solution or a non-aqueous solution can be applied, or a gel polymer electrolyte in which they are held by a polymer matrix, a polymer electrolyte, and an inorganic solid electrolyte may be used. Further, different electrolytes may be used on the positive electrode side and the negative electrode side using a solid electrolyte or a separator.

<Supporting electrolyte salt>
Conventionally known electrolyte electrolyte salts can be used. As the supporting electrolyte salt, potassium chloride, sodium chloride, potassium hydroxide, sodium carbonate, sodium hydrogen carbonate and the like can be used without any problem as long as they have desired ionic conductivity, and aqueous solutions and non-aqueous solutions thereof can be preferably used. .

In particular, when considering conduction of lithium ions, an electrolytic solution in which a supporting electrolyte salt containing lithium is dissolved in water or a non-aqueous solvent is used.
As the supporting electrolyte salt, LiBF ₄ , LiClO ₄ , LiPF ₆ , LiAsF ₆ , LiSbF ₆ , LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, LiC ₄ F ₉ SO ₃ , Li (CF ₃ SO ₂ ) ₃ C, LiI, LiBr, LiCl, LiAlCl, LiHF ₂ , LiSCN, or LiBPh ₄ (where Ph is a phenyl group) and the like are exemplified, but not limited thereto.

The non-aqueous solvent is not particularly limited.
Carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, ethyl methyl carbonate, and diethyl carbonate;
Lactones such as γ-butyrolactone, γ-valerolactone, and γ-octanoic lactone;
Glymes such as tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane, 4-methyl-1,3-dioxolane, 1,2-methoxyethane, 1,2-ethoxyethane, and 1,2-dibutoxyethane;
Esters such as methyl formate, methyl acetate, and methyl propionate;
Sulfoxides such as dimethyl sulfoxide and sulfolane; and
Nitriles such as acetonitrile are exemplified. These solvents may be used alone or in combination of two or more.

  Furthermore, when the electrolyte solution is a polymer electrolyte held in a polymer matrix and made into a gel, the polymer matrix includes an acrylate resin having a polyalkylene oxide segment, a polyphosphazene resin having a polyalkylene oxide segment, and a polyelectrolyte. Examples include, but are not limited to, a polysiloxane having an alkylene oxide segment.

<Separator>
A conventionally well-known material used for an air battery can be used as a separator. Specifically, as the liquid electrolyte, for example, polyethylene fiber, polypropylene fiber, glass fiber, resin nonwoven fabric, glass nonwoven fabric, filter paper, and the like can be used.

  Hereinafter, the present invention will be described based on examples, but the present invention is not limited thereto. In Examples and Comparative Examples, unless otherwise specified, “part” means “part by mass” and “%” means “% by mass”.

(Synthesis Example 1)
A reaction vessel equipped with a gas introduction tube, a thermometer, a condenser, and a stirrer was charged with 200.0 parts of n-butanol and replaced with nitrogen gas. The reaction vessel was heated to 110 ° C., and a mixture of 60.0 parts of styrene, 140.0 parts of acrylic acid, and 12.0 parts of V-601 (manufactured by Wako Pure Chemical Industries, Ltd.) as a polymerization initiator was taken over 2 hours. Then, the polymerization reaction was carried out. After completion of the dropwise addition, the mixture was further reacted at 110 ° C. for 3 hours, 0.6 parts of V-601 (manufactured by Wako Pure Chemical Industries, Ltd.) was added, and the reaction was further continued at 110 ° C. for 1 hour to obtain a copolymer solution. Obtained. Furthermore, after adding 400 parts of water and making it aqueous, it heated to 100 degreeC, butanol was azeotroped with water, and butanol was distilled off. Dilution with water gave an aqueous solution of an aqueous resin dispersant (1) having a nonvolatile content of 20%.
(Synthesis Example 2)
A reaction vessel equipped with a gas introduction tube, a thermometer, a condenser, and a stirrer was charged with 200.0 parts of n-butanol and replaced with nitrogen gas. The inside of the reaction vessel was heated to 110 ° C., and 100.0 parts of styrene, 60.0 parts of acrylic acid, 40.0 parts of dimethylaminoethyl methacrylate, and V-601 (manufactured by Wako Pure Chemical Industries, Ltd.) 12 as a polymerization initiator. 0.0 part of the mixture was added dropwise over 2 hours to carry out the polymerization reaction. After completion of the dropwise addition, the mixture was further reacted at 110 ° C. for 3 hours, 0.6 parts of V-601 (manufactured by Wako Pure Chemical Industries, Ltd.) was added, and the reaction was further continued at 110 ° C. for 1 hour to obtain a copolymer solution. . Further, after cooling to room temperature, 74.2 parts of dimethylaminoethanol was added for neutralization. This is an amount that neutralizes 100% of the carboxyl groups in the copolymer. Furthermore, after adding 400 parts of water and making it aqueous, it heated to 100 degreeC, butanol was azeotroped with water, and butanol was distilled off.
Dilution with water gave an aqueous solution of an aqueous resin dispersant (2) having a nonvolatile content of 20%.

<Non-platinum carbon catalyst (CAC)>
[Production Example 1]
Graphene nanoplatelets xGnP-C-750 (manufactured by XGscience) and iron phthalocyanine P-26 (manufactured by Sanyo Dye) are weighed so that the mass ratio is 1 / 0.5 (graphene nanoplatelets / iron phthalocyanine). Then, dry mixing was performed with a particle composite apparatus Mechanofusion (manufactured by Hosokawa Micron Corporation) to obtain a mixture. The mixture was filled in an alumina crucible and heat-treated at 800 ° C. for 2 hours in a nitrogen atmosphere in an electric furnace to obtain a non-platinum carbon catalyst (CAC1).

[Production Example 2]
Ketjen Black EC-300J (manufactured by Lion) and iron phthalocyanine P-26 (manufactured by Sanyo Dye) were weighed so that the mass ratio would be 1 / 0.5 (Ketjen black / iron phthalocyanine). Dry mixing was performed using a chemical device Mechanofusion (manufactured by Hosokawa Micron Corporation) to obtain a mixture. The above mixture was filled in an alumina crucible and heat-treated at 800 ° C. for 2 hours in a nitrogen atmosphere in an electric furnace to obtain a non-platinum carbon catalyst (CAC2).

<ORR activity evaluation>
As described below, the ORR (oxidation-reduction reaction) activity of the CAC obtained above was evaluated and confirmed to have oxygen reduction activity.
1. Inking 0.01g of CAC was weighed and 0.02g of 20% by weight Nafion dispersion solution (DE2020CStype, manufactured by Wako Pure Chemical Industries, Ltd.) was used as a binder, 0.02g of pure water, 1.31g of ethanol, butanol as a dispersion solvent After adding 0.13 g, dispersion treatment was performed with ultrasonic waves (45 kHz) for 15 minutes to prepare an evaluation ink.
2. Preparation of working electrode After polishing the surface of the rotating electrode (glassy carbon electrode radius 0.15 cm) to a mirror surface, 7.5 μL of the ink for evaluation above is dropped on the electrode surface and dried naturally by spin coating at 1500 rpm. A working electrode was prepared.
3. Linear sweep voltammetry (LSV) measurement An electrolytic solution (0.5 M sulfuric acid aqueous solution) is placed in an electrolytic cell equipped with the working electrode prepared above, a counter electrode (platinum), and a reference electrode (reversible hydrogen electrode RHE). After sufficiently bubbling oxygen therein, LSV measurement was performed in a scanning range of +1.2 V (vs RHE) to +0.05 V (vs RHE) while rotating the working electrode at 2000 rpm.
(After bubbling with nitrogen in the electrolytic solution, the value obtained by performing LSV measurement in the same scanning range as the measurement in an oxygen atmosphere was used as the background.)
The ORR active potential was calculated by reading the potential when the current density reached −10 μA / cm ² and converting it to a potential based on the reversible hydrogen electrode (RHE).
Since the ORR active potential of the CAC was 0.8 V (vs RHE), it was confirmed to have oxygen reduction activity.

<Preparation of electrode paste composition>
[Examples 1 to 22]
According to the composition shown in Table 1, various aqueous liquid media (D) and a water-soluble resin type dispersant (C) are charged into a glass bottle, and then the total of the conductive carbon material (A) and the oxygen reduction catalyst (B) is 10 In addition, 5.0 parts of a 60 mass% PTFE aqueous dispersion (Mitsui / DuPont Fluorochemical Co., Ltd., 60% polytetrafluoroethylene aqueous dispersion; 31-J) was added as a binder. Furthermore, after adding zirconia beads as a medium, it was dispersed with a paint shaker to prepare electrode paste compositions (1) to (22), respectively.

[Comparative Examples 1-4]
According to the composition shown in Table 1, various aqueous liquid media (D) are charged into a glass bottle and added in various proportions so that the total of the conductive carbon material (A) and the oxygen reduction catalyst (B) is 10 parts. After adding 5.0 parts of 60 mass% PTFE aqueous dispersion (Mitsui / DuPont Fluorochemical Co., Ltd., 60% polytetrafluoroethylene aqueous dispersion; 31-J), and further adding zirconia beads as a medium, a paint shaker was used. Dispersed to prepare electrode paste compositions (23) to (26), respectively.

  In Table 1, water / IPA = 1/1 represents a mixed solvent in which water and isopropyl alcohol are mixed in the same amount at a mass ratio. The same applies to water / BuOH = 4/1 and water / PGM = 1/1.

<Preparation of positive electrode layer for air battery>

  The electrode paste compositions (1) to (22) of Examples 1 to 22 and the electrode paste compositions (23) to (26) of Comparative Examples 1 to 4 are carbon fibers as a conductive support using a doctor blade. After coating on a carbon paper base material (TGP-H-090, manufactured by Toray Industries, Inc.), it was dried in an air atmosphere at 95 ° C. for 60 minutes to prepare air battery positive electrode layers (1) to (26).

<Coating property evaluation>
The positive electrode for an air battery was evaluated by the coating property evaluation shown below. The positive electrode for aeroelectricity was observed with a video microscope VHX-900 (manufactured by Keyence Corporation) at a magnification of 500 times, and coating unevenness (unevenness: evaluated by the density of the positive electrode layer) and pinholes (defects where the positive electrode layer was not applied) The evaluation was made according to the following criteria. The evaluation results are shown in Table 2.

(village)
○: The density of the positive electrode layer is not confirmed (good).
Δ: There are 2 to 3 shades of the positive electrode layer, but it is a very small region (no problem in practical use).
X: A large number of shades of the positive electrode layer are confirmed, or one or more of the stripes having a length of 5 mm or more (defective).
(Pinhole)
○: No pinholes are confirmed (good).
Δ: There are 2 to 3 pinholes but they are very small (defect).
X: Many pinholes are confirmed, or one or more pinholes having a diameter of 1 mm or more (very poor).

<Air battery characteristics evaluation>
Below, it demonstrates about the method of producing a metal-air battery using the positive electrode produced from the electrode paste composition of this invention, and characteristic evaluation.

<Manufacture of cell for magnesium air primary battery>
Using a Mg plate as the negative electrode and positive electrode layers (1) to (26) for the air battery as the positive electrode, a separator (nonwoven fabric) was sandwiched and fixed between the two electrodes to obtain a magnesium air primary battery evaluation cell.

<Characteristic evaluation of magnesium air primary battery: open circuit voltage, discharge capacity>
The electrolytic solution (20% aqueous sodium chloride solution) was immersed in the separator of the obtained magnesium-air primary battery evaluation cell, and the open circuit voltage (OCV) and discharge capacity of the constituent cells were measured with a charge / discharge evaluation apparatus (potentiostat). In the case where the positive electrode layers (1) to (22) for the air battery were used as the positive electrode, the open circuit voltage was 1.5 to 2.0 V and the discharge capacity was 1100 to 1500 mAh / g, whereas the positive electrode for the air battery In the layers (23) to (26), the open circuit voltage was 1.1 to 1.3 V, and the discharge capacity was 500 to 900 mAh / g.

<Preparation of evaluation cell for lithium-air secondary battery>
Separator (porous polypropylene film) containing a non-aqueous electrolyte solution (1M LiPF ₆ , ethylene carbonate / diethyl carbonate = 1/1, volume ratio) on a Li foil, solid electrolyte (manufactured by OHARA, LiCGC Plate 1 inch × 150 μmt), and fixed with an aluminum laminate film. At this time, the aluminum laminate film on the solid electrolyte side was cut to a size of 16 mm square to produce an exposed surface of the solid electrolyte, and a negative electrode for an air battery was produced.
On the solid electrolyte of the negative electrode for the air secondary battery, a non-woven fabric impregnated with a 1M LiCl aqueous solution as an aqueous electrolyte is placed, and then the positive electrode layers (1) to (26) for the air battery are disposed. The evaluation cell for lithium air secondary batteries was obtained by fixing and thermocompression bonding.

<Characteristic evaluation of lithium-air secondary battery: Capacity maintenance ratio>
Using the obtained lithium-air secondary battery evaluation cell, a three-cycle break-in operation was performed under the conditions of a cut-off voltage of 2.0 to 4.8 V and a current density of 0.5 mA / cm ² . Thereafter, a capacity retention rate (percentage of the discharge capacity at the 30th cycle with respect to the discharge capacity at the 1st cycle) was determined by performing a charge / discharge test of 30 cycles under the same conditions. ) To (22) had a capacity retention rate of 91 to 95.5%, whereas the positive electrode layers for air cells (23) to (26) had a capacity retention rate of 35 to 65%.

  As described above, in the positive electrode layer for an air battery manufactured in the comparative example as compared with the example, all showed high battery characteristics. In the examples, the dispersibility of the electrode paste was remarkably improved, so that coating unevenness and pinholes were improved, and oxygen necessary for the reaction of the air battery could be supplied to the entire positive electrode layer, in addition to the oxygen reduction reaction. It is thought that the battery characteristics were improved because the reaction surface area of the carbon material and oxygen reduction catalyst used as the field could be increased.

Claims (9)

An air battery electrode paste composition comprising a conductive carbon material (A) and / or an oxygen reduction catalyst (B), a water-soluble resin-type dispersant (C), and an aqueous liquid medium (D). And
The water-soluble resin type dispersant (C) is one or more selected from the group consisting of a resin having a basic functional group, a resin having an acidic functional group, a resin having a basic functional group and an acidic functional group, and a nonionic resin. The electrode paste composition for air batteries which is resin.   The electrode paste composition for an air battery according to claim 1, wherein the water-soluble resin type dispersant (C) is a polyvinyl resin.   The electrode paste composition for an air battery according to claim 1 or 2, wherein the water-soluble resin type dispersant (C) is a nonionic resin.   The electrode paste composition for an air battery according to any one of claims 1 to 3, wherein the conductive carbon material (A) is one or more carbon materials selected from the group consisting of carbon black, graphene-based carbon materials, and carbon nanotubes.   5. The electrode paste for an air battery according to claim 1, wherein the oxygen reduction catalyst (B) is one or more oxygen reduction catalysts selected from the group consisting of a supported metal catalyst, an oxide-based catalyst, and a non-platinum-based carbon catalyst. Composition. The electrode paste composition for an air battery according to any one of claims 1 to 5, further comprising a binder. The electrode paste composition for an air battery according to any one of claims 1 to 6, further comprising a supporting electrolyte salt. The positive electrode material for air batteries formed using the composition in any one of Claims 1-7. The air battery formed using the composition in any one of Claims 1-7, or the positive electrode material of Claim 8.