JP6743454B2 - Electrode paste composition for air battery, positive electrode material for air battery, and air battery - Google Patents

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.

The air battery currently under development is an energy system that uses a metal as a negative electrode active material and oxygen in the air as a positive electrode active material to generate electricity and store electricity. Since the active material on the positive electrode side can use oxygen in the air, there is no need to fill the positive electrode active material inside the battery, which has the advantage that the energy density can be increased compared to other conventional batteries.
For this reason, for example, zinc-air primary batteries have already become widespread as light-weight and high-capacity batteries for hearing aids, and research and development of lithium-air secondary batteries as in-vehicle batteries that require high-capacity batteries are vigorous. Is done in a regular manner.

Since the structure of an air battery changes depending on the type of negative electrode metal, the presence/absence of charging, the operating environment, etc., the types of members used and the required characteristics also vary. However, the positive electrode layer, which has the function of reducing oxygen in the air, is a common member regardless of whether it is a primary battery or a secondary battery, and because the material greatly affects the voltage and capacity of the battery, active research is being conducted. Has been done.

Various measures have been taken so far to improve the output by improving the positive electrode layer. For example, use of a positive electrode material in which carbon nanotubes are doped with N (Patent Document 1), or a positive electrode layer having a laminated structure of a catalyst layer and a liquid-tight gas-permeable layer, and the catalyst layer includes hydrophilic particles in addition to carbon particles and catalyst particles. It has been reported to use a porous layer containing Pd (Patent Document 2). However, in these reports, the kind of material used for the positive electrode material is not sufficiently dispersed, and in particular, the carbon material is likely to cause agglomeration, so that a conduction path is formed in the entire positive electrode layer and diffusion of oxygen molecules into the entire film is performed. However, there is a problem in that the electromotive force and the current amount are reduced. Further, it has been reported that a mixture of polyvinyl alcohol and activated carbon is sprayed to improve the adhesion to the reaction surface of the positive electrode body (Patent Document 3). However, in this report, since only activated carbon with low conductivity is used in the film, the resistance of the film is high and the electron conduction path necessary for the positive electrode reaction cannot be sufficiently secured, and the molecular weight of polyvinyl alcohol is about 600. Since it is low and the dispersion effect due to steric hindrance is low, it is difficult to stabilize and stabilize the activated carbon, resulting in a non-uniform membrane, and it is difficult to realize high battery performance.

JP, 2005-220036, A JP, 2005-79577, A JP-A-10-326631

The problem to be solved by the present invention is to disperse a conductive carbon material (A) and/or an oxygen reduction catalyst (B) constituting a positive electrode layer of an air battery using a water-soluble resin type dispersant (C). It is to provide an electrode paste composition having good dispersibility and excellent coatability by producing an electrode paste composition for an air battery. Further, by using the electrode paste composition of the present invention, a positive electrode material for an air battery, in which coating unevenness and pinholes of the electrode when applied are extremely small, and an air battery having the same and having excellent battery performance Is to provide.

The present inventors have accomplished the present invention as a result of earnest researches for solving the above problems.
That is, the present invention provides an electrode for an air battery 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). A paste composition,
The water-soluble resin type dispersant (C) is at least one 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 present invention relates to a resin electrode paste composition for an air battery.
Further, the present invention relates to the above electrode paste composition for an air battery, wherein the water-soluble resin type dispersant (C) is a polyvinyl resin.

The present invention also relates to the above air battery electrode paste composition, wherein the water-soluble resin type dispersant (C) is a 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 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. Regarding

The present invention also relates to the above electrode paste composition for an air battery, which further comprises a binder.

The present invention also relates to the above electrode paste composition for an air battery, which further comprises a supporting electrolyte salt.

The present invention also relates to a positive electrode material for an air battery formed by using the above composition.

The present invention also relates to an air battery formed by using the above composition or the above positive electrode material.

According to the present invention, a conductive carbon material (A) and/or an oxygen reduction catalyst (B) that constitutes a positive electrode layer of an air battery is dispersed using a water-soluble resin-type dispersant (C), By preparing the electrode paste composition, the dispersibility is good, and it becomes possible to provide an electrode paste composition having excellent coatability, and therefore the coating unevenness of the electrode when coated and It is possible to obtain the positive electrode material for an air battery with extremely few pinholes and the air battery including the same. Therefore, it becomes 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 air battery" may be referred to as "electrode paste composition" or "paste composition". In addition, "resin" may be referred to as "polymer".

<Electrode paste composition for air battery>
The electrode paste composition of the present invention contains 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 requires a binder. Optionally containing a supporting electrolyte salt.
The ratios of the conductive carbon material (A) and/or the oxygen reduction catalyst (B), the water-soluble resin type dispersant (C), the aqueous liquid medium (D), the binder and the supporting electrolyte salt are not particularly limited. Instead, it 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% by mass based on the conductive carbon material (A) and/or the oxygen reduction catalyst (B) in the electrode paste composition. Is about 5% by 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 the oxygen reduction can be reduced. 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 coating and drying the electrode paste composition.

Further, 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 as an example the case of an electrode paste composition containing a conductive carbon material (A) and/or an oxygen reduction catalyst (B), a water-soluble resin type dispersant (C), a binder and an aqueous liquid medium (D) explain.
For example,
(X-1) A conductive carbon material (A) and/or a conductive carbon material (A) containing an oxygen reduction catalyst (B), a water-soluble resin type dispersant (C), and an aqueous liquid medium (D), and Alternatively, an electrode paste composition can be obtained by obtaining an aqueous dispersion of the oxygen reduction catalyst (B) and adding a binder to the aqueous dispersion.
(X-2) A conductive carbon material (A) containing a conductive carbon material (A) and/or an oxygen reduction catalyst (B), a water-soluble resin type dispersant (C), a binder and an aqueous liquid medium (D). And/or an aqueous dispersion of the oxygen reduction catalyst (B) can be obtained to obtain an electrode paste composition.
(X-3) A solution containing a water-soluble resin-type dispersant (C), a binder and an aqueous liquid medium (D) is obtained, and a conductive carbon material (A) and/or an oxygen reduction catalyst (B) is further added. Thus, 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 reducing activity as referred to in the present invention, but graphite, carbon black. The conductive carbon fibers (carbon nanotubes, carbon nanofibers, carbon fibers), fullerenes and the like can be used alone or in combination of two or more. It is preferable to use carbon black in terms of conductivity, availability, and cost.

As carbon black, furnace black produced by continuously thermally decomposing a gas or liquid raw material in a reaction furnace, especially Ketjen black made from ethylene heavy oil, and burning the raw material gas to burn the flame into the channel steel bottom surface. Channel blacks that have been rapidly cooled and deposited, and thermal blacks obtained by periodically repeating combustion and thermal decomposition using gas as a raw material, especially various types such as acetylene black using acetylene gas as a raw material, or 2 More than one type can be used together. Further, commonly used oxidation-treated carbon black, hollow carbon and the like can also be used.

The oxidation treatment of carbon is carried out by subjecting carbon to high temperature in air or secondary treatment with nitric acid, nitrogen dioxide, ozone, etc. This is a treatment for directly introducing (covalently bonding) an oxygen-containing polar functional group onto the surface of carbon, and is generally performed to improve the dispersibility of carbon. However, since the conductivity of carbon generally decreases as the amount of introduced functional groups increases, it is preferable to use carbon that has not been oxidized.

The larger the specific surface area of the carbon black used, the more the contact points between the carbon black particles increase, which is advantageous in reducing the internal resistance of the electrode. Specifically, the specific surface area (BET) obtained from the adsorption amount of nitrogen 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, and more preferably 100 m ² /G or more,
It is desirable to use those of 1500 m ² /g or less. When 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 exceeding 1500 m ² /g may be difficult to obtain as a commercial material. is there.

The particle size of carbon black used is preferably 0.005 to 1 μm in primary particle size, and particularly preferably 0.01 to 0.2 μm. However, the primary particle size mentioned here is an average of the particle sizes measured by an electron microscope or the like.

The dispersed particle size of the conductive carbon material (A) in the electrode paste composition is preferably made finer to 0.03 μm or more and 5 μm or less. It may be difficult to prepare a composition having a dispersed particle diameter of the carbon material of less than 0.03 μm. Further, when a composition in which the dispersed particle diameter of the carbon material exceeds 5 μm is used, problems such as variations in material distribution of the electrode paste coating film and variations in resistance distribution may occur.
The term “dispersed particle size” as used herein means a particle size (D50) at which the volume ratio of particles becomes 50% when the volume ratio of the particles is integrated in the volume particle size distribution, and is generally known. Particle size distribution meter, for example, a dynamic light scattering particle size distribution meter (“Microtrac UPA” manufactured by Nikkiso Co., Ltd.).

Examples of commercially available carbon blacks include Toka Black #4300, #4400, #4500, #5500 (Tokai Carbon Co., Furnace Black), Printex L, etc. (Degussa Co., Furnace Black), Raven 7000, 5750, 5250, 5000 ULTRAIII, 5000 ULTRA, etc., Conducttex SC ULTRA
, Conductex 975 ULTRA, etc., PUER BLACK 100, 115, 2
05 etc. (manufactured by Colombian, furnace black), #2350, #2400B, #2600B, #3050B, #3030B, #3230B, #3350B, #3400B, #5400B etc. (manufactured by Mitsubishi Chemical Co., furnace black), MONARCH1400, 1300, 900, VulcanXC-72R, BlackPearls2000 and the like (Cabot, furnace black), Ensaco250G, Ensaco260G, Ensaco350G, SuperP-Li (manufactured by TIMCAL), Ketjenblack EC-300J, EC-600JD (manufactured by Akzo). Examples of graphite such as Denka Black, Denka Black HS-100, FX-35 (acetylene black manufactured by Denki Kagaku Kogyo Co., Ltd.) include natural graphite such as artificial graphite, flake graphite, lump graphite, and earth graphite. However, it is not limited to these, and two or more kinds may be used in combination.

As the conductive carbon fiber, one obtained by firing from a petroleum-derived raw material is preferable, but one obtained by firing from a plant-derived raw material can also be used. For example, VGCF manufactured by Showa Denko KK manufactured from a petroleum-derived raw material may 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 it is 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, and particle diameter.Therefore, an optimal material that meets the required performance and cost in the intended use is selected. To be selected.

Having oxygen reducing activity in the present invention means having a function of electrochemically reducing oxygen molecules in a gas state or a dissolved state in a liquid, in an acidic aqueous solution saturated with oxygen. It means that the oxygen reduction reaction potential (ORR potential) is 0.5 V (vsRHE; reversible hydrogen electrode) or more when linear sweep voltammetry is measured by the rotating disk electrode method. The ORR potential was a potential at a current density of −10 μA/cm ² at 2000 rpm rotation in an acidic aqueous solution saturated with oxygen. The ORR potential means that the higher the voltage, the easier the adsorption or dissociation of oxygen molecules on the oxygen reduction catalyst (B) occurs, and the activation energy required for the reaction can be lowered, so that the energy in the reaction can be reduced. 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, and particle diameter.Therefore, an optimal material that meets the required performance and cost in the intended use is selected. To be selected.

In the supported metal catalyst, a precious metal element such as platinum or a base metal element other than those is used as a metal serving as a catalyst. Noble metals such as platinum, palladium, rhodium, and gold are preferable from the viewpoint of high catalytic action, and they may be used as nanoparticles or alloyed to increase the effective specific surface area. Materials such as carbon materials, oxides, and polymers can be used as the carrier, but in consideration of the function as an electrode, it is sometimes preferable to use conductive carbon materials.

The oxide-based catalyst is oxide particles containing a transition metal and an oxygen element as main components, and conventionally known ones can be used. Controlling the crystal structure and shape of oxide particles, particle size, introduction of oxygen vacancies, doping with different elements such as nitrogen, and reducing particle size can improve catalytic properties such as oxygen adsorption capacity and electron conductivity. It has an effect on and has an important meaning for expressing a high oxygen reducing ability. As an element constituting the oxide, 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 an aggregate of carbon (C) atoms, and physical or chemical between the constituent units. A catalyst material that has an interaction (bond) and contains a different element, for example, a heteroatom such as N, B, or P, or a base metal element, and has one or more carbon materials or nitrogen elements and base metal elements. The compound can be obtained by mixing and heat treatment, and conventionally known compounds can be used. The base metal element here is a metal element excluding precious metal elements (ruthenium, rhodium, palladium, silver, osmium, iridium, platinum, gold) among transition metal elements, and the base metal element includes cobalt, iron, nickel, It is preferable to contain one or more selected from manganese, copper, titanium, vanadium, chromium, zinc, tin, aluminum and magnesium.
Containing a hetero atom and a base metal element is important for having oxygen reduction activity. Generally, in the case of a carbon-based catalyst material, the base metal in the structure (called base metal-N4 structure) where four nitrogens are arranged in a plane, centering on the base metal element on the surface of the carbon material, is the catalytic active point. Examples include elements and carbon atoms in the vicinity of heteroatoms introduced at the edge portion of the carbon material surface.

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

<Water-soluble resin type dispersant (C)>
The water-soluble resin type dispersant (C) used in the present invention can effectively function as a dispersant for the conductive carbon material (A) and/or the oxygen reduction catalyst (B) and can alleviate the aggregation thereof. 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), Considering the dispersibility of the carbon material (A) and/or the oxygen reduction catalyst (B), coating suitability, etc., 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 described later.

The resin having a basic functional group contains a cyclic amino group and a skeleton obtained by neutralizing a part or all of the amino group or a quaternary ammonium salt,
Homopolymers of polymerizable monomers such as dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, methylethylaminoethyl (meth)acrylate, dimethylaminostyrene and diethylaminostyrene, or other polymerizable monomers And copolymers thereof and acid neutralized products thereof.

As the resin having an acidic functional group, a carboxyl group, a sulfo group, a phosphoric acid group and a skeleton obtained by neutralizing a part or all of them,
A polymerizable monomer having a carboxyl group such as maleic acid, fumaric acid, itaconic acid, citraconic acid, acrylic acid, methacrylic acid, crotonic acid, and cinnamic acid,
Sulfones 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, methacroyl oxyethyl acid phosphate monoethanolamine salt, 3-chloro-2-acid phosphooxypropyl methacrylate, acid phosphooxy polyoxyethylene glycol monomethacrylate, acid phosphooxy poly Oxypropylene glycol methacrylate, (meth)acryloyloxyethyl acid phosphate, (meth)acryloyloxypropyl acid phosphate, (meth)acryloyloxy-2-hydroxypropyl acid phosphate, (meth)acryloyloxy-3-hydroxypropyl acid phosphate, ( (Meth)acryloyloxy-3-chloro-2-hydroxypropyl acid phosphate, homopolymer of a polymerizable monomer having a phosphoric acid group such as allyl alcohol acid phosphate, or a copolymer with another polymerizable monomer And alkali neutralized products thereof.

The resin having a basic functional group and an acidic functional group means a resin having both the basic skeleton and the acidic skeleton, and is a copolymer of styrene-maleic acid-N,N-dimethylaminoethyl (meth)acrylate. Things can be mentioned.

The nonionic resin is a resin having the basic functional group, a resin having an acidic functional group, a water-soluble resin other than a resin having a basic functional group and an acidic functional group, polyvinylpyrrolidone, polyvinyl alcohol, polyacrylamide, poly -N-vinyl acetamide, polyalkylene glycol, etc. are mentioned.

Further, 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 type saturated hydrocarbon group include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate and the like having 1 carbon atom. Alkyl (meth)acrylate having 22 to 22 carbon atoms, preferably an alkyl group-containing acrylate or a corresponding methacrylate having an alkyl group having 2 to 12 carbon atoms, more preferably 2 to 8 carbon atoms. These alkyl groups may be branched, and specific examples thereof include isopropyl(meth)acrylate, isobutyl(meth)acrylate, tertiary butyl(meth)acrylate, 2-ethylhexyl(meth)acrylate, 2-butylhexyl(meth). ) Acrylate and the like.
In addition, 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.
Further, 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 the polymerizable monomer having a cyclic saturated hydrocarbon group include isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, cyclohexyl (meth)acrylate, trimethylcyclohexyl (meth)acrylate, 1-adamantyl (meth)acrylate. Etc.

The polymerizable monomer having a polyoxyalkylene structure, such as diethylene glycol mono (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, has a hydroxyl group at the terminal and has a polyoxyalkylene chain. Having monoacrylate or monomethacrylate, methoxyethylene glycol (meth)acrylate, methoxydiethylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, methoxypolypropylene glycol (meth)acrylate, etc., having an alkoxy group at the terminal, 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, cyclic compounds such as glycidyl (meth)acrylate and tetrahydrofurfuryl (meth)acrylate may be used.

As the polymerizable monomer having a hydroxyl group, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, glycerol mono (meth)acrylate, 4-hydroxystyrene, Examples thereof 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 resulting copolymer with sodium hydroxide or the like.

Examples of the nitrogen-containing polymerizable monomer include N-vinyl-2-pyrrolidone, (meth)acrylamide, N-vinylacetamide, N-methylol(meth)acrylamide, N-methoxymethyl-(meth)acrylamide, etc. Examples include roll (meth)acrylamide, N,N-di(methylol)acrylamide, N-methylol-N-methoxymethyl(meth)acrylamide, N,N-di(methoxymethyl)acrylamide and the like.

Further, as other monomers, perfluoromethylmethyl(meth)acrylate, perfluoroethylmethyl(meth)acrylate, 2-perfluorobutylethyl(meth)acrylate, 2-perfluorohexylethyl(meth)acrylate, etc. Perfluoroalkylalkyl(meth)acrylates having a perfluoroalkyl group having 1 to 20 carbon atoms;
Perfluoroalkyl ethylene such as perfluorobutyl ethylene, perfluorohexyl ethylene, perfluorooctyl ethylene, perfluorodecyl ethylene, perfluoroalkyl group-containing vinyl monomer such as alkylenes, 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 these compounds can be used.

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

The water-soluble resin type dispersant (C) is, in addition to the polyvinyl resin described above, a polyurethane resin, a polyester resin, a polyether resin, a cellulose resin such as carboxymethyl cellulose, a formalin condensate, a silicone resin, or a composite thereof. Examples thereof include polymers. Furthermore, two or more kinds of these water-soluble resin type dispersants (C) may be used in combination.

Examples of commercially available water-soluble resin dispersants (C) include Disperbyk-180, 183, 184, 185, 187, 190, 191, 192, 193, 194, 198, 199, 2010, 2012, 2015, 2020, 2091, 2095, 2096 and the like (manufactured by Big Chemie), SOLSPERSE 20000, 27,000, 40000, 41090, 44000, 46000, 47,000, 64000, 65000, 66000 (manufactured by Nippon Lubrizol), Floren G-700AMP, G-700DMEA, WK. -13E, GW-1500, GW-1640, etc. (manufactured by Kyoeisha Chemical Co., Ltd.), BorchiR Gen1350, 0851, 1253, SN95, WNS, etc. (manufactured by Matsuo Sangyo Co., Ltd.), TEGO Dispersers 650, 651, 652, 655, 660C, 715W, 740W, 750W. , 752W, 755W, 760W (manufactured by Tomoe Kogyo Co., Ltd.), polyvinylpyrrolidone PVP-K30, K85, K90 etc. (manufactured by ISP Japan Co., Ltd.), S-REC 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 (manufactured by Sekisui Chemical Co., Ltd.), carboxy Methyl cellulose CMC1105, 1110, 1130, 1140, 1170, 1190, 1205, 1210, 1240, 1250 and the like (manufactured by Daicel Chemical Industries Ltd.) can be mentioned, but the invention is not limited thereto.

The mass average molecular weight of the water-soluble resin type dispersant (C) is 3000 or more and less than 500000 from the point that the dispersibility of the conductive carbon material (A) and/or the oxygen reduction catalyst (B) is good. It is preferably 5000 or more and less than 400000.

<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, in order to improve the coating property on the conductive support, a liquid medium compatible with water is used. You may do it.
Examples of the liquid medium that is 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. Examples thereof include ethers, ethers, nitriles, etc., and may be used in a range 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 an alcohol solvent having 4 or less carbon atoms is preferable. 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. As the polyhydric alcohol, specifically, propylene glycol, ethylene glycol and the like are preferable, 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 those particles in a solvent is small. It is a thing.
As the binder, it is possible to use conventionally known ones, for example, acrylic resin, polyurethane resin, polyester resin, phenol resin, epoxy resin, phenoxy resin, urea resin, melamine resin, alkyd resin, formaldehyde resin, silicone resin, Examples thereof include fluororesins, synthetic rubbers such as styrene-butadiene rubber and fluororubber, conductive resins such as polyaniline and polyacetylene, and polyvinylidene fluoride, polyvinyl fluoride, and polymer compounds containing a fluorine atom such as tetrafluoroethylene. Further, it may be a modified product, a mixture, or a copolymer of these resins, and may be a water-soluble resin or a water-dispersible resin. These binders may be used alone or in combination of two or more.

When the aqueous liquid medium (D) is used, a binder generally called an aqueous emulsion can also be used. The aqueous emulsion is one in which the binder resin is not dissolved in water and is dispersed in the form of fine particles.

The emulsion to be used is not particularly limited, but (meth)acrylic emulsion, nitrile emulsion, urethane emulsion, diene emulsion (SBR etc.), fluorine emulsion (PVDF, PTFE etc.) and the like can be mentioned.

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

For example, mixers such as a disperser, a homomixer, or a planetary mixer; homogenizers such as "Clearmix" manufactured by M Technique Co., Ltd. or "Fillmix" manufactured by PRIMIX; paint shakers (manufactured by Red Devil), ball mills, sand mills Media type dispersing machine such as (Dimino Mill manufactured by Shinmaru Enterprises Co., Ltd.), attritor, pearl mill (“DCP mill” manufactured by Eirich, etc.), or co-ball mill; wet jet mill (“Genus PY” manufactured by Genus, Sugino) Machineless "Starburst", Nanomizer "Nanomizer", etc.), M Technique "Clear SS-5", or Nara Machinery "MICROS" medialess disperser; or other roll mills, etc. However, the present invention is not limited to these. Further, as the disperser, it is preferable to use a disperser that has been subjected to a metal mixing prevention treatment.

For example, when using a media type disperser, a method in which the agitator and vessel are made of a ceramic or resin disperser, or a metal agitator and a disperser in which the vessel surface is treated with tungsten carbide spraying or resin coating, etc. Is preferably used. Then, as the medium, it is preferable to use glass beads, or ceramic beads such as zirconia beads or alumina beads. 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.

<Cathode layer for air batteries>
The positive electrode layer for an air battery is formed by directly applying the electrode paste composition to a conductive support (carbon paper or the like) and drying it.
The method for applying the electrode paste composition is not particularly limited, and examples thereof include knife coaters, bar coaters, blade coaters, sprayers, dip coaters, spin coaters, roll coaters, die coaters, curtain coaters, and screen printing. A general method can be applied.

After coating, it is dried to form a coating film (catalyst layer for air battery). The drying temperature is usually about 40 to 200°C, preferably about 70 to 120°C. The drying time is usually about 5 minutes to 2 hours, preferably about 30 minutes to 1 hour, though 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 is preferable so that a gas can pass through and diffuse on the positive electrode side so as to take in oxygen in the air. Furthermore, since electrons need to be taken in and out, a material having conductivity must be used. Carbon paper, carbon felt, carbon cloth and the like made of a carbon material 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 utilizing an oxygen reduction reaction on the positive electrode side by the generated e ⁻ (electrons) and metal ions. Also works.
As the configuration of the metal-air battery, 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 the conduction of metal ions between the positive electrode and the negative electrode. It consists of an electrolyte layer and a separator.
As the positive electrode, the air battery electrode paste composition of the present invention can be preferably used.

<Negative electrode material>
As the negative electrode, a metal material composed of a simple 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, S i, Ca, T i, V, Cr, M n, and Fe. These metal carriers and alloys are applied. You can also However, the material is not limited to these, and conventionally known materials applied to air batteries can be used.

<Electrolyte layer>
The electrolyte layer conducts metal ions between the positive electrode and the negative electrode of the above 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 may be applied, or a gel polymer electrolyte holding them in a polymer matrix, a polymer electrolyte or an inorganic solid electrolyte may be used. Further, different solid electrolytes and separators may be used, and different electrolyte solutions may be used on the positive electrode side and the negative electrode side.

<Supporting electrolyte salt>
As the supporting electrolyte salt, a conventionally known one can be used. As the supporting electrolyte salt, there is no problem as long as it has a desired ionic conductivity, and potassium chloride, sodium chloride, potassium hydroxide, sodium carbonate, sodium hydrogen carbonate or the like can be used, and an aqueous solution or non-aqueous solution thereof can be preferably used. ..

In particular, considering the conduction of lithium ions, as the electrolytic solution, a supporting electrolyte salt containing lithium dissolved in water or a non-aqueous solvent is used.
Examples of the supporting electrolyte salt include 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 ) Examples thereof include, but are not limited to, ₃ C, LiI, LiBr, LiCl, LiAlCl, LiHF ₂ , LiSCN, and LiBPh ₄ (however, Ph is a phenyl group).

The non-aqueous solvent is not particularly limited, for example,
Carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, ethylmethyl 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
Examples thereof include nitriles such as acetonitrile. Further, these solvents may be used alone, or two or more kinds may be mixed and used.

Further, when the above-mentioned electrolytic solution is a polymer electrolyte which is held in a polymer matrix and is in the form of a gel, the polymer matrix includes an acrylate resin having a polyalkylene oxide segment, a polyphosphazene resin having a polyalkylene oxide segment, and a polyphosphazene resin. Examples thereof include, but are not limited to, polysiloxane having an alkylene oxide segment.

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

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

(Synthesis example 1)
200.0 parts of n-butanol was charged into a reaction vessel equipped with a gas introduction tube, a thermometer, a condenser, and a stirrer, and the atmosphere was replaced with nitrogen gas. The inside of 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 used for 2 hours. Then, the mixture was dropped to carry out a polymerization reaction. After completion of dropping, the mixture was further reacted at 110° C. for 3 hours, then 0.6 part 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 prepare a copolymer solution. Obtained. Further, 400 parts of water was added to make the solution water-soluble, and then heated to 100° C., butanol was azeotropically distilled with water, and the butanol was distilled off. It was diluted with water to obtain an aqueous solution of an aqueous resin type dispersant (1) having a nonvolatile content of 20%.
(Synthesis example 2)
200.0 parts of n-butanol was charged into a reaction vessel equipped with a gas introduction tube, a thermometer, a condenser, and a stirrer, and the atmosphere was 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.) as a polymerization initiator 12 0.0 part of the mixture was added dropwise over 2 hours to carry out a polymerization reaction. After completion of dropping, the mixture was further reacted at 110° C. for 3 hours, 0.6 part 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 to neutralize. This is the amount that neutralizes 100% of the carboxyl groups in the copolymer. Further, 400 parts of water was added to make the solution water-soluble, and then heated to 100° C., butanol was azeotropically distilled with water, and butanol was distilled off.
Diluted with water to obtain an aqueous solution of an aqueous resin type dispersant (2) having a nonvolatile content of 20%.

<Non-platinum based carbon catalyst (CAC)>
[Production Example 1]
Graphene nanoplatelets xGnP-C-750 (manufactured by XGscience) and iron phthalocyanine P-26 (manufactured by Sanyo Pigment Co., Ltd.) are weighed so that the mass ratio is 1/0.5 (graphene nanoplatelets/iron phthalocyanine). Then, dry mixing was performed using a particle complexing device Mechanofusion (manufactured by Hosokawa Micron Co., Ltd.) 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-based carbon catalyst (CAC1).

[Production Example 2]
Ketjenblack EC-300J (manufactured by Lion Corporation) and iron phthalocyanine P-26 (manufactured by Sanyo Pigment Co., Ltd.) were weighed so that the mass ratio was 1/0.5 (Ketjenblack/iron phthalocyanine), and the particle composite was obtained. The mixture was obtained by dry-mixing with a chemical device Mechanofusion (manufactured by Hosokawa Micron). 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-based carbon catalyst (CAC2).

<ORR activity evaluation>
The ORC (oxidation-reduction reaction) activity of the CAC obtained above was evaluated as described below, and it was confirmed that it had oxygen reduction activity.
1. Ink formation 0.01 g of CAC was weighed, 0.02 g of 20 mass% Nafion dispersion solution (DE2020CStype by Wako Pure Chemical Industries, Ltd.) as a binder, 0.02 g of pure water, 1.31 g 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 the surface of the rotating electrode (the radius of the glassy carbon electrode was 0.15 cm) was polished to a mirror surface, 7.5 μL of the above evaluation ink was dropped on the electrode surface and naturally dried while spin-coating at 1500 rpm. A working electrode was prepared.
3. Linear sweep voltammetry (LSV) measurement Put the electrolytic solution (0.5M sulfuric acid aqueous solution) into an electrolytic cell equipped with the working electrode prepared above, the counter electrode (platinum), and the reference electrode (reversible hydrogen electrode RHE) After sufficiently bubbling oxygen into the inside, LSV measurement was performed in a scanning range of +1.2 V (vsRHE) to +0.05 V (vsRHE) while rotating the working electrode at 2000 rpm.
(After bubbling with nitrogen in the electrolytic solution, a value obtained by performing LSV measurement in the same scanning range as measurement in an oxygen atmosphere was used as the background.)
The ORR activation potential was calculated by reading the potential at the time when the current density reached −10 μA/cm ² and converting it to the potential based on the reversible hydrogen electrode (RHE).
Since the ORR activation potential of the CAC was 0.8 V (vsRHE), it was confirmed that the CAC had oxygen reduction activity.

<Preparation of electrode paste composition>
[Examples 1 to 22]
According to the composition shown in Table 1, a glass bottle was charged with various aqueous liquid media (D) and a water-soluble resin-type dispersant (C), and then the total of the conductive carbon material (A) and the oxygen reduction catalyst (B) was 10%. And 60 parts by mass of a PTFE aqueous dispersion solution (Mitsui DuPont Fluorochemical Co., Ltd., 60% polytetrafluoroethylene aqueous dispersion; 31-J) as a binder were added in an amount of 5.0 parts by weight. Further, zirconia beads were added as a medium and then dispersed with a paint shaker to prepare electrode paste compositions (1) to (22), respectively.
However, Example 19 is a reference example.

[Comparative Examples 1 to 4]
According to the composition shown in Table 1, various aqueous liquid media (D) were charged in a glass bottle, and the conductive carbon material (A) and the oxygen reduction catalyst (B) were added at respective ratios so as to be 10 parts, and as a binder. After adding 5.0 parts of 60 mass% PTFE aqueous dispersion solution (Mitsui DuPont Fluorochemical Co., Ltd., 60% polytetrafluoroethylene aqueous dispersion; 31-J), and further adding zirconia beads as a medium, use a paint shaker. Dispersion was performed 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 were mixed in the same amount by 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 were carbon fibers as a conductive support by a doctor blade. Was coated on a carbon paper base material (TGP-H-090, manufactured by Toray Industries, Inc.) and dried in an air atmosphere at 95° C. for 60 minutes to prepare positive electrode layers (1) to (26) for an air battery.

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

(village)
◯: Density of the positive electrode layer is not confirmed (good).
(Triangle|delta): There are 2 to 3 density|concentrations of a positive electrode layer, but it is a very minute area|region (it does not have a problem practically).
Poor: A large number of shades of the positive electrode layer are confirmed, or one or more stripes having a shade of 5 mm or more (defective).
(Pinhole)
◯: No pinhole is confirmed (good).
Δ: There are 2 to 3 pinholes, but they are extremely small (defective).
X: Many pinholes are confirmed, or one or more pinholes with a diameter of 1 mm or more (extremely defective).

<Air battery characteristic evaluation>
Hereinafter, a method for producing a metal-air battery and a characteristic evaluation using a positive electrode produced from the electrode paste composition of the present invention will be exemplified.

<Preparation of cells for magnesium-air primary battery>
A Mg plate was used as a negative electrode, and the positive electrode layers (1) to (26) for an air battery were used as a positive electrode, and a separator (nonwoven fabric) was sandwiched and fixed between both 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% sodium chloride aqueous 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 by a charge/discharge evaluation device (potentiostat). In the case where the positive electrode layers (1) to (22) for an air battery were used as the positive electrode, the open voltage was 1.5 to 2.0 V and the discharge capacity was 1100 to 1500 mAh/g, whereas the positive electrode for an air battery was In 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>
A 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, a solid electrolyte (LiCGC Plate 1inch×Ohara Co., Ltd.) 150 μmt) was placed and fixed with an aluminum laminate film. At this time, the aluminum laminate film on the solid electrolyte side was cut into a size of 16 mm square to form an exposed surface of the solid electrolyte, and a negative electrode for an air battery was prepared.
On the solid electrolyte of the negative electrode for the air secondary battery, a non-woven fabric impregnated with 1M LiCl aqueous solution as an aqueous electrolytic solution, and then the positive electrode layers (1) to (26) for the air battery are arranged, and an aluminum laminate film is used. An evaluation cell for a lithium-air secondary battery was obtained by fixing and thermocompression bonding.

<Characteristic evaluation of lithium-air secondary battery: capacity retention rate>
Using the obtained lithium-air secondary battery evaluation cell, a 3-cycle break-in operation was performed under the conditions of a cutoff voltage of 2.0-4.8 V and a current density of 0.5 mA/cm ² . After that, the capacity retention (percentage of the discharge capacity at the 30th cycle relative to the discharge capacity at the first cycle) was obtained by performing a charge/discharge test for 30 cycles under the same conditions. ) To (22), the capacity retention rate was 91 to 95.5%, whereas the capacity retention rate was 35 to 65% for the air battery positive electrode layers (23) to (26).

As described above, each of the air battery positive electrode layers produced in the comparative examples exhibited higher battery characteristics than the examples. In the examples, the dispersibility of the electrode paste was remarkably improved, 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. It is considered that the battery characteristics were improved because the reaction surface area of the carbon material and the oxygen reduction catalyst to be used could be increased.

Claims (9)

An electrode paste composition for an air battery, comprising an electrically conductive carbon material (A) and/or an oxygen reduction catalyst (B), a water-soluble resin type dispersant (C), and an aqueous liquid medium (D). hand,
The water-soluble resin type dispersant (C) is at least one 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. Ri resin der,
The content of the water-soluble resin dispersant (C) is, per 100 weight% of the conductive carbon material (A) and / or oxygen reduction catalyst (B), 3 to 30% by mass Ru air primary battery Electrode paste composition for use. The electrode paste composition for an air primary battery according to claim 1, wherein the water-soluble resin type dispersant (C) is a polyvinyl resin. The electrode paste composition for an air primary 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 primary battery according to claim 1, 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 electrode for an air primary battery according to any one of claims 1 to 4, 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. Paste composition. Further, the electrode paste composition for an air primary battery according to claim 1, further comprising a binder. The electrode paste composition for an air primary battery according to claim 1, further comprising a supporting electrolyte salt. A positive electrode material for an air primary battery, which is formed by using the composition according to claim 1. An air primary battery formed using the composition according to claim 1 or the positive electrode material according to claim 8.