JP2017084475A - Electrode material and electrode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrode material which enables the enhancement in the resistance of an electrode against oxidation.SOLUTION: An electrode material comprises resin particles 11, and a catalyst metal 12. The resin particles 11 are 1000 Ω cm or less in resistivity, and 100 N/mm2 or more in compression modulus when the resin particles 11 are compressed by 10%. The resin particles 11 include carbon black, graphite, graphitized carbon, boron carbide, carbon nanotube, diamond, fullerene or graphene, and have an aspect ratio of 5 or less. It is preferable that the electrode material further comprises carbon particles. The catalyst metal 12 is supported by the resin particles 11.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an electrode material used for forming an electrode. The present invention also relates to an electrode using the above electrode material.

  For an electrode of a fuel cell or the like, for example, an electrode material in which a catalytic metal is supported on carbon is used. Carbon is excellent in conductivity and has a property of being chemically stable in a fuel cell environment (high potential and strong acidity). For this reason, carbon is generally used as the carrier contained in the fuel cell electrode.

  However, the oxidation resistance of carbon is low. Carbon is electrochemically oxidized by the reaction represented by the following formula (1) under the operating conditions of the fuel cell.

C + 2H ₂ O → CO ₂ + 4H ⁺ + 4e ⁻ (1)

  This reaction proceeds gradually. For this reason, when the fuel cell is operated for a long time, the carbon is thinned, resulting in a problem that the performance of the fuel cell is deteriorated.

  This problem can be addressed to some extent by increasing the crystallinity of carbon and reducing the specific surface area. However, when the specific surface area of carbon is reduced, the portion for supporting the catalyst metal is reduced, so that the catalyst metal is supported on the carbon as coarse particles. As a result, there arises a problem that the catalytic activity is lowered.

  A method for increasing the catalytic activity with respect to the above problems is disclosed in Patent Document 1 below. A method for enhancing oxidation resistance and catalytic activity is disclosed in Patent Document 2 below.

  Patent Document 1 discloses that a carrier having a 90% particle size D90 of a particle size cumulative curve of 28 μm or less when a particle size distribution is measured by a light scattering method is used as a carrier for supporting a catalyst metal. In Patent Document 1, specifically, carbon having a controlled particle size is used as a carrier.

  Patent Document 2 discloses that boron carbide is used in place of carbon as a carrier for supporting a catalyst metal.

WO2009 / 051111A JP 2014-49289 A

  Even if the particle size is controlled as described in Patent Document 1, it is difficult to obtain sufficient oxidation resistance of the electrode because the carbon is thinned, the electrode performance is deteriorated. In addition, the present inventors have found that when carbon is thinned, the stress applied to the electrode increases, the power generation efficiency of the fuel cell decreases, and the reliability of the fuel cell decreases.

  Also in Patent Document 2, it is difficult to sufficiently increase the oxidation resistance of the electrode.

  The objective of this invention is providing the electrode material which can improve the oxidation tolerance of an electrode. Moreover, the objective of this invention is providing the electrode using the said electrode material.

  According to a wide aspect of the present invention, there is provided an electrode material comprising resin particles and a catalyst metal, wherein the resin particles have a resistivity of 1000 Ω · cm or less.

It is preferable that the compression elastic modulus when the resin particles are compressed by 10% is 100 N / mm ² or more.

  In a specific aspect of the electrode material according to the present invention, the catalyst metal is supported on the resin particles.

It is preferable that a compression elastic modulus when the particle composite in which the catalyst metal is supported on the resin particles is compressed by 10% is 100 N / mm ² or more.

  On the specific situation with the electrode material which concerns on this invention, the said resin particle contains carbon.

  In a specific aspect of the electrode material according to the present invention, the resin particles include carbon black, graphite, graphitized carbon, boron carbide, carbon nanotube, diamond, fullerene, or graphene.

  On the specific situation with the electrode material which concerns on this invention, the aspect-ratio of the said resin particle is 5 or less.

  In a specific aspect of the electrode material according to the present invention, the electrode material includes carbon particles.

  The electrode material according to the present invention is suitably used for forming a fuel cell electrode.

  According to a wide aspect of the present invention, an electrode formed of the electrode material described above is provided.

  The electrode material according to the present invention includes resin particles and a catalyst metal, and the resistivity of the resin particles is 1000 Ω · cm or less. Therefore, when the electrode is formed using the electrode material according to the present invention, the electrode material The oxidation resistance of can be increased.

FIG. 1 is a cross-sectional view showing resin particles and catalyst metal contained in an electrode material according to an embodiment of the present invention.

  Details of the present invention will be described below.

  The electrode material according to the present invention is used to form an electrode. The electrode material according to the present invention includes resin particles and a catalytic metal. In the electrode material according to the present invention, the resin particles have a resistivity of 1000 Ω · cm or less.

  In the electrode material according to the present invention, since the above-described configuration is adopted, when the electrode is formed using the electrode material, the oxidation resistance of the electrode can be increased. Unlike carbon, the resin particles whose resistivity is not more than the above upper limit are less likely to fade. For this reason, even if an electrode is used for a long period of time, the shape of the resin particle is maintained, and as a result, the shape of the electrode and the porosity of the electrode are maintained. As a result, the catalytic activity is also kept high.

  An electrode material can be suitably used as the electrode, and since the catalytic activity is effectively exhibited, the catalyst metal is preferably supported on the resin particles. In the electrode material, the resin particles and the catalyst metal are preferably a particle composite in which the catalyst metal is supported on the resin particles. The electrode material preferably includes a plurality of particle composites.

  FIG. 1 is a cross-sectional view showing resin particles and catalyst metal contained in an electrode material according to an embodiment of the present invention.

  In the resin particles 11 and the catalyst metal 12 shown in FIG. 1, the catalyst metal 12 is supported on the resin particles 11. The resin particles 11 and the catalyst metal 12 are the particle composite 1 in which the catalyst metal 12 is supported on the resin particles 11.

  The resistivity of the resin particles is 1000 Ω · cm or less. From the viewpoint of effectively increasing the conductivity, the resistivity of the resin particles is preferably 500 Ω · cm or less, more preferably 300 Ω · cm or less. The lower limit of the resistivity of the resin particles is not particularly limited.

  From the viewpoint of effectively increasing the conductivity, the resistivity of the particle composite is preferably 1000 Ω · cm or less, more preferably 500 Ω · cm or less, and even more preferably 300 Ω · cm or less. The lower limit of the resistivity of the particle composite is not particularly limited.

  The resistivity of the resin particles is measured as follows. The resistivity of the particle composite is similarly measured.

  After putting 1.5 g of the resin particles in a cylindrical container (diameter 20 mm, vertical length 50 mm), a pressure load of 63.7 MPa and a compressive load of 20 kN were applied to the resin particles with a pressurizer with a load cell. Apply up and down. And DC resistance is measured using the low resistivity meter (Model MCP-T610: Mitsubishi Chemical Analytech Co., Ltd.), and a resistivity is calculated by the following formula. The smaller the resistivity, the better the conductivity.

  Resistivity = measured value × cross-sectional area of resin particles after compression in a cylindrical container (horizontal direction with respect to the cylindrical container) / thickness of resin particles after compression

  The aspect ratio of the resin particles is preferably 5 or less, more preferably 3 or less, and still more preferably 2 or less. The aspect ratio indicates a major axis / minor axis. The resin particles are preferably spherical. Spherical means that the aspect ratio is 2 or less.

  The average particle diameter of the resin particles is preferably 0.1 μm or more, more preferably 1.0 μm or more, preferably 10.0 μm or less, more preferably 5.0 μm or less. When the average particle diameter is equal to or more than the lower limit, the porosity of the electrode can be appropriately increased, and the power generation efficiency of a fuel cell or the like can be efficiently increased. When the average particle size is not more than the above upper limit, the catalytic activity is further increased.

  The average particle diameter of the resin particles indicates a number average particle diameter. The average particle size can be measured using, for example, a Coulter counter (manufactured by Beckman Coulter).

  The average major axis of the catalyst metal is preferably 5 nm or more, more preferably 10 nm or more, preferably 500 nm or less, more preferably 50 nm or less. When the average major axis is equal to or more than the lower limit, the power generation efficiency of a fuel cell or the like can be efficiently increased. When the average major axis is not more than the above upper limit, the catalytic activity is further increased.

  The average major axis of the catalyst metal can be measured from an image taken with an electron microscope. The average major axis of the catalyst metal is selected, for example, by randomly selecting 100 electrode materials using a field emission transmission electron microscope (FE-TEM) (“JEM-ARM200F” manufactured by JEOL Ltd.). It can be measured at double.

  The ratio of the average long diameter of the catalyst metal to the average particle diameter of the resin particles (the average long diameter of the catalyst metal / the average particle diameter of the resin particles) is preferably 0.0001 or more, more preferably 0.001 or more, preferably Is 0.1 or less, more preferably 0.01 or less.

  From the viewpoint of effectively increasing the catalytic activity, the CV value (coefficient of variation) of the particle diameter of the resin particles is preferably 10% or less, more preferably 5% or less, and even more preferably 3% or less. The CV value of the particle diameter of the resin particles is calculated by the following formula.

  CV value of resin particle diameter (%) = standard deviation of resin particle diameter / average particle diameter of resin particles × 100

From the viewpoint of further maintaining the shape of the electrode and the porosity of the electrode and suppressing the decrease in power generation efficiency due to the long-term use of the fuel cell, the compression modulus (10% K value) when the resin particles are compressed by 10% ) Is preferably 100 N / mm ² or more, more preferably 500 N / mm ² or more, and still more preferably 1000 N / mm ² or more. When the compression elastic modulus is equal to or higher than the lower limit, an increase in stress applied to the electrode is suppressed, and the reliability of the fuel cell is further enhanced over a long period. From the viewpoint of further maintaining the shape of the electrode and the porosity of the electrode and suppressing the decrease in power generation efficiency due to the long-term use of the fuel cell, the compression modulus (10% K value) when the resin particles are compressed by 10% ) Is preferably 10,000 N / mm ² or less, more preferably 5000 N / mm ² or less.

From the viewpoint of further maintaining the shape of the electrode and the porosity of the electrode, and suppressing the decrease in power generation efficiency due to long-term use of the fuel cell, the compression modulus (10% K) when the particle composite is compressed by 10% The value is preferably 100 N / mm ² or more, more preferably 500 N / mm ² or more, still more preferably 1000 N / mm ² or more, and particularly preferably 1500 N / mm ² or more. When the compression elastic modulus is equal to or higher than the lower limit, an increase in stress applied to the electrode is suppressed, and the reliability of the fuel cell is further enhanced over a long period. From the viewpoint of further maintaining the shape of the electrode and the porosity of the electrode, and suppressing the decrease in power generation efficiency due to long-term use of the fuel cell, the compression modulus (10% K) when the particle composite is compressed by 10% value) is preferably 12000N / mm ² or less, and more preferably not more than 8000 N / mm ^2.

  The 10% K value of the resin particles and the particle composite can be measured as follows.

  Using a micro-compression tester, resin particles or particle composites are compressed under a condition that a smooth tester end face of a cylinder (diameter 50 μm, made of diamond) is loaded at 25 ° C. and a maximum test load of 90 mN over 30 seconds. The load value (N) and compression displacement (mm) at this time are measured. From the measured value obtained, the compression elastic modulus is obtained by the following formula. As the micro compression tester, for example, “Fischer Scope H-100” manufactured by Fischer is used.

K value (N / mm ² ) = (3/2 ^1/2 ) · F · S ⁻³ / ² · R ^−1/2
F: Load value (N) when the resin particle or particle composite is 10% compressively deformed
S: Compression displacement (mm) when resin particles or particle composites are 10% compressively deformed
R: radius of resin particle or particle composite (mm)

  In the electrode material, with respect to 100 parts by weight of the resin particles, the content of the catalyst metal is preferably 1 part by weight or more, more preferably 30 parts by weight or more, preferably 95 parts by weight or less, more preferably 60 parts by weight or less. When the content of the catalyst metal is not less than the above lower limit, the catalyst activity and oxidation resistance are effectively increased.

  From the viewpoint of enhancing conductivity, the electrode material may contain carbon particles. A catalytic metal may be supported on the carbon particles. It is preferable that a catalyst metal is supported on the resin particles or the carbon particles. The resin particles can be used as a partial substitute for conventional carbon particles.

  In the electrode material, the ratio of the content of the resin particles to the content of the carbon particles is preferably 0.01 or more, more preferably 0.1 or more, further preferably 1 or more, based on weight. Is 100 or less, more preferably 10 or less. When the content of the resin particles is relatively increased, oxidation resistance and stress relaxation properties are further enhanced. When the content of the carbon particles is relatively increased, the conductivity is further increased. From the viewpoint of further improving the oxidation resistance and stress relaxation properties, it is preferable to increase the content of the resin particles and decrease the content of the carbon particles.

  In the electrode material, the ratio of the content of the particle composite in which the catalyst metal is supported on the resin particles to the content of the particle composite in which the catalyst metal is supported on the carbon particles is preferably 0.01 or more on a weight basis. More preferably, it is 0.1 or more, More preferably, it is 1 or more, Preferably it is 100 or less, More preferably, it is 10 or less. When the content of the particle composite in which the catalyst metal is supported on the resin particles is relatively increased, the oxidation resistance and the stress relaxation property are further increased. When the content of the particle composite in which the catalytic metal is supported on the carbon particles is relatively increased, the conductivity is further increased. From the viewpoint of further improving the oxidation resistance and stress relaxation properties, the content of the particle composite in which the catalyst metal is supported on the resin particles is increased, and the content of the particle composite in which the catalyst metal is supported on the carbon particles. Is preferably reduced.

  Although it does not specifically limit as a manufacturing method of the said particle composite, The method of removing a solvent after adding and mixing a catalyst metal to the dispersion liquid which disperse | distributed the resin particle in the solvent is mentioned.

  Hereinafter, other details such as resin particles, catalytic metals, electrodes, and applications will be described. In the following description, “(meth) acryl” means one or both of “acryl” and “methacryl”, and “(meth) acrylate” means one or both of “acrylate” and “methacrylate”. means.

(Resin particles)
The resin particles include a resin. Various organic materials are suitably used as the material (resin) of the resin particles. Examples of the resin particle material (resin) include polyolefin resins such as polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyisobutylene, and polybutadiene; acrylic resins such as polymethyl methacrylate and polymethyl acrylate; Terephthalate, polycarbonate, polyamide, phenol formaldehyde resin, melamine formaldehyde resin, benzoguanamine formaldehyde resin, urea formaldehyde resin, phenol resin, melamine resin, benzoguanamine resin, urea resin, epoxy resin, unsaturated polyester resin, saturated polyester resin, polysulfone, polyphenylene oxide , Polyacetal, polyimide, polyamideimide, polyetheretherketone Polyethersulfone, and polymers such as obtained by a variety of polymerizable monomer having an ethylenically unsaturated group is polymerized with one or more thereof. Resin particles having any compression property suitable for electrode materials can be designed and synthesized, and the compression elastic modulus of the resin particles can be easily controlled within a suitable range. It is preferably a polymer obtained by polymerizing one or more polymerizable monomers having a plurality of polymerizable unsaturated groups.

  When the resin particles are obtained by polymerizing a monomer having an ethylenically unsaturated group, the monomer having the ethylenically unsaturated group may be a non-crosslinkable monomer or a crosslinkable monomer. And a polymer.

  Examples of the non-crosslinkable monomer include styrene monomers such as styrene and α-methylstyrene; carboxyl group-containing monomers such as (meth) acrylic acid, maleic acid, and maleic anhydride; (Meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate, cyclohexyl ( Alkyl (meth) acrylates such as meth) acrylate and isobornyl (meth) acrylate; oxygen such as 2-hydroxyethyl (meth) acrylate, glycerol (meth) acrylate, polyoxyethylene (meth) acrylate and glycidyl (meth) acrylate (Meth) acrylates; nitrile-containing monomers such as (meth) acrylonitrile; vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether; vinyl acids such as vinyl acetate, vinyl butyrate, vinyl laurate, vinyl stearate Esters; Unsaturated hydrocarbons such as ethylene, propylene, isoprene and butadiene; Halogen-containing monomers such as trifluoromethyl (meth) acrylate, pentafluoroethyl (meth) acrylate, vinyl chloride, vinyl fluoride and chlorostyrene Is mentioned.

  Examples of the crosslinkable monomer include tetramethylolmethane tetra (meth) acrylate, tetramethylolmethane tri (meth) acrylate, tetramethylolmethane di (meth) acrylate, trimethylolpropane tri (meth) acrylate, and dipenta Erythritol hexa (meth) acrylate, dipentaerythritol penta (meth) acrylate, glycerol tri (meth) acrylate, glycerol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) Polyfunctional (meth) acrylates such as acrylate, (poly) tetramethylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate; triallyl (iso) cyanure And silane-containing monomers such as triallyl trimellitate, divinylbenzene, diallyl phthalate, diallylacrylamide, diallyl ether, γ- (meth) acryloxypropyltrimethoxysilane, trimethoxysilylstyrene, vinyltrimethoxysilane It is done.

  From the viewpoint of effectively increasing oxidation resistance, effectively increasing stress relaxation, and suppressing reduction in power generation efficiency due to long-term use of the fuel cell, the resin particles are (meth) acrylic resin, silicone resin or divinyl. It preferably contains a benzene polymer resin or an epoxy resin.

  The resin particles can be obtained by polymerizing the polymerizable monomer having an ethylenically unsaturated group by a known method. Examples of this method include a method of suspension polymerization in the presence of a radical polymerization initiator, and a method of polymerizing by swelling a monomer together with a radical polymerization initiator using non-crosslinked seed particles.

  From the viewpoint of enhancing conductivity, the resin particles preferably include a conductive material.

  Examples of the conductive material include carbon black, graphite, graphitized carbon, boron carbide, carbon nanotube, diamond, fullerene, graphene, titania, silica, ceria, alumina, magnesia, zirconia, and yttria.

  From the viewpoint of effectively increasing conductivity and effectively increasing oxidation resistance, the resin particles preferably contain carbon black, graphite, graphitized carbon, boron carbide, carbon nanotubes, diamond, fullerene, or graphene. . The diamond is preferably nanodiamond.

  From the viewpoint of effectively increasing the conductivity and effectively increasing the oxidation resistance, the conductive material is preferably carbon black.

  Carbon black is not particularly limited, and examples thereof include ketjen black, acetylene black, channel black, and furnace black. In order to improve the dispersibility of carbon black, carbon black subjected to surface treatment such as microlith (manufactured by Ciba Geigy) can also be used.

  From the viewpoint of effectively increasing the conductivity and effectively increasing the oxidation resistance, the resin particles preferably include ketjen black. From the viewpoint of effectively increasing oxidation resistance, the resin particles preferably contain carbon black in the resin particles. Some carbon blacks may be disposed on the surface of the resin particles.

  In the resin particles, the content of the conductive material contained in the resin particles with respect to 100 parts by weight of the resin is preferably 5 parts by weight or more, more preferably 50 parts by weight or more, and preferably 95 parts by weight or less. More preferably, it is 80 parts by weight or less. When the content of the conductive material is not less than the above lower limit and not more than the above upper limit, catalytic activity and oxidation resistance are effectively increased.

  In the resin particle, the content of carbon contained in the resin particle is preferably 5 parts by weight or more, more preferably 50 parts by weight or more, and preferably 95 parts by weight or less, with respect to 100 parts by weight of the resin. The amount is preferably 80 parts by weight or less. When the carbon content is not less than the above lower limit and not more than the above upper limit, the catalytic activity and the oxidation resistance are effectively increased.

(Catalyst metal)
Examples of the catalyst metal include noble metals. Examples of the catalyst metal include platinum, palladium, ruthenium, rhodium, iridium, osmium, gold and silver. The catalyst metal may be a single metal or an alloy. The alloy may be an alloy of a noble metal and a metal other than the noble metal. Examples of the alloy include a platinum-cobalt alloy, a platinum-ruthenium alloy, and a platinum-iridium alloy. As for the said catalyst metal, only 1 type may be used and 2 or more types may be used together.

  From the viewpoint of effectively increasing the catalytic activity, the catalytic metal is preferably platinum, a platinum alloy, or palladium.

(electrode)
An electrode can be formed of the electrode material.

  Although it does not specifically limit as a manufacturing method of the said electrode material, After adding a catalyst metal to the dispersion liquid which disperse | distributed the resin particle in the solvent, and mixing, the liquid mixture is apply | coated to predetermined thickness and a solvent is removed. Examples thereof include a method, an electrode material containing a solvent, or a method in which a solution obtained by adding a solvent to an electrode material is applied to a predetermined thickness and the solvent is removed.

  Heat treatment can be performed when removing the solvent.

  The temperature of the heat treatment is not particularly limited. The temperature of the heat treatment is preferably 50 ° C. or higher, more preferably 100 ° C. or higher, preferably less than the melting point temperature of the resin particles, more preferably the melting point temperature of the resin particles is −5 ° C. or lower.

(Use)
The electrode material is suitably used for obtaining a fuel cell electrode. The electrode is preferably a fuel cell electrode.

  The electrode material may be used for applications other than fuel cell electrodes. Applications other than fuel cell electrodes include lithium ion battery electrodes.

  The fuel cell includes, for example, a first electrode and a second electrode (a fuel electrode and an air electrode) and an electrolyte. It is preferable that at least one of the first electrode and the second electrode is the fuel cell electrode using the electrode material. When only one of the first electrode and the second electrode is the fuel cell electrode using the electrode material, the other electrode is not particularly limited. Conventionally known electrodes can be used as the other electrodes.

  Examples of the fuel cell include a polymer electrolyte fuel cell (PEFC), a phosphoric acid fuel cell (PAFC), a molten carbonate fuel cell (MCFC), a solid oxide fuel cell (SOFC), and an alkaline electrolyte fuel cell. (AFC) and direct fuel cell (DFC).

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. The present invention is not limited only to the following examples.

Example 1
(1) Production of resin particles Resin particles using carbon black were produced as follows.

  60 parts by weight of tetramethylol methane triacrylate, 20 parts by weight of divinylbenzene and 20 parts by weight of acrylonitrile were uniformly mixed, and 40 parts by weight of carbon black was further added. Thereafter, carbon black was uniformly dispersed over 48 hours using a bead mill to obtain a polymerizable monomer composition.

  To the obtained polymerizable monomer composition, 2 parts by weight of benzoyl peroxide was uniformly mixed to obtain a mixed solution. The above mixed solution was put into 850 parts by weight of a 3% strength by weight aqueous polyvinyl alcohol solution and well stirred. Thereafter, the colored polymerizable monomer droplets were suspended with a homogenizer so that the particle diameter was about 0.5 to 5.0 μm, and a suspension was obtained.

  The obtained suspension was transferred to a 2 liter separable flask equipped with a thermometer, a stirrer and a reflux condenser, heated to 85 ° C. with stirring in a nitrogen atmosphere, and subjected to a polymerization reaction for 7 hours. Further, the temperature was raised to 90 ° C. and maintained for 3 hours to complete the polymerization reaction to obtain a polymerization reaction solution. Thereafter, the polymerization reaction liquid was cooled, and the produced resin particles were filtered, sufficiently washed with water and dried to obtain 120 parts by weight of particles having an average particle diameter of 2.5 μm. The obtained particles were classified to obtain resin particles.

  In the obtained resin particles, the content of carbon black was 48 parts by weight with respect to 100 parts by weight of the resin.

(2) Preparation of electrode material (particle composite in which catalyst metal is supported on resin particles) (1) Add 1.0 g of resin particles obtained in the preparation of resin particles to 1 L of pure water, and stir uniformly. A dispersion was obtained by dispersing.

  To the obtained dispersion, hediamminedinitroplatinum (II) nitric acid solution containing 0.5 g of platinum metal was added, and the mixture was sufficiently stirred to be blended with the resin particles to obtain a suspension (1).

  A 10% aqueous ammonia solution was added to the suspension (1) to adjust the pH to 8.5, and then 0.5 g / L potassium borohydride solution was added as a reducing agent solution at a dropping rate of 0.1 ml / min. It was dripped at. During the dropping of the reducing agent solution, the generated platinum nuclei were adhered to the resin particles while being dispersed by ultrasonic stirring. Thereafter, the mixture was stirred until the pH became stable, and it was confirmed that hydrogen foaming stopped, and a suspension (2) was obtained.

  Thereafter, the suspension (2) was filtered to take out the particles and washed with water to obtain particles in which platinum was formed as a catalyst metal on the surface of the resin particles. The particles were dried at 100 ° C. for 24 hours to obtain an electrode material (particle composite). When the obtained electrode material was measured by XRD, the average major axis of the catalyst metal was 8.4 nm.

  In the obtained particle composite, the content of the catalyst metal was 36 parts by weight with respect to 100 parts by weight of the resin particles. The ratio of the average major axis of the catalyst metal to the average particle diameter of the resin particles was 0.005.

(3) Production of electrode Using the obtained particle composite, a single cell electrode for a polymer electrolyte fuel cell was produced as follows.

The particle composite was dispersed in an organic solvent together with Nafion manufactured by DuPont to obtain a dispersion. The obtained dispersion was applied onto a fluororesin sheet to form a catalyst layer. The amount of platinum catalyst per electrode area was 0.5 mg / cm ² . Two electrodes formed of the particle composite were bonded together by hot pressing through a polymer electrolyte membrane to obtain a laminate. A diffusion layer was placed on both sides of the obtained laminate to obtain a single cell electrode (thickness 50 μm).

(Examples 2 to 12)
Resin particles were obtained in the same manner as in Example 1 except that the amount of the resin particle material (resin) was changed as shown in Table 1 below. Using the obtained resin particles, an electrode material (particle composite) and an electrode were produced in the same manner as in Example 1. The coated carbon black used in Example 7 is carbon black whose surface is coated with polyethylene.

  Details of the resin particles and the particle composite in Examples 2 to 12 are as follows.

Example 2:
In the obtained resin particles, the content of carbon black was 24 parts by weight with respect to 100 parts by weight of the resin. In the obtained particle composite, the content of the catalyst metal was 36 parts by weight with respect to 100 parts by weight of the resin particles. The ratio of the average major axis of the catalyst metal to the average particle diameter of the resin particles was 0.005.

Example 3:
In the obtained resin particles, the carbon black content was 72 parts by weight with respect to 100 parts by weight of the resin. In the obtained particle composite, the content of the catalyst metal was 36 parts by weight with respect to 100 parts by weight of the resin particles. The ratio of the average major axis of the catalyst metal to the average particle diameter of the resin particles was 0.005.

Example 4:
In the obtained resin particles, the content of carbon black was 48 parts by weight with respect to 100 parts by weight of the resin. In the obtained particle composite, the content of the catalyst metal was 36 parts by weight with respect to 100 parts by weight of the resin particles. The ratio of the average major axis of the catalyst metal to the average particle diameter of the resin particles was 0.005.

Example 5:
In the obtained resin particles, the content of carbon black was 48 parts by weight with respect to 100 parts by weight of the resin. In the obtained particle composite, the content of the catalyst metal was 36 parts by weight with respect to 100 parts by weight of the resin particles. The ratio of the average major axis of the catalyst metal to the average particle diameter of the resin particles was 0.005.

Example 6:
In the obtained resin particles, the content of carbon black was 48 parts by weight with respect to 100 parts by weight of the resin. In the obtained particle composite, the content of the catalyst metal was 36 parts by weight with respect to 100 parts by weight of the resin particles. The ratio of the average major axis of the catalyst metal to the average particle diameter of the resin particles was 0.005.

Example 7:
In the obtained resin particles, the content of the coated carbon black was 39 parts by weight with respect to 100 parts by weight of the resin. In the obtained particle composite, the content of the catalyst metal was 36 parts by weight with respect to 100 parts by weight of the resin particles. The ratio of the average major axis of the catalyst metal to the average particle diameter of the resin particles was 0.005.

Example 8:
In the obtained resin particles, the content of graphitized carbon was 48 parts by weight with respect to 100 parts by weight of the resin. In the obtained particle composite, the content of the catalyst metal was 36 parts by weight with respect to 100 parts by weight of the resin particles. The ratio of the average major axis of the catalyst metal to the average particle diameter of the resin particles was 0.005.

Example 9:
In the obtained resin particles, the content of boron carbide was 48 parts by weight with respect to 100 parts by weight of the resin. In the obtained particle composite, the content of the catalyst metal was 36 parts by weight with respect to 100 parts by weight of the resin particles. The ratio of the average major axis of the catalyst metal to the average particle diameter of the resin particles was 0.005.

Example 10:
In the obtained resin particles, the graphene content was 48 parts by weight with respect to 100 parts by weight of the resin. In the obtained particle composite, the content of the catalyst metal was 36 parts by weight with respect to 100 parts by weight of the resin particles. The ratio of the average major axis of the catalyst metal to the average particle diameter of the resin particles was 0.005.

Example 11:
In the obtained resin particles, the content of fullerene was 48 parts by weight with respect to 100 parts by weight of the resin. In the obtained particle composite, the content of the catalyst metal was 36 parts by weight with respect to 100 parts by weight of the resin particles. The ratio of the average major axis of the catalyst metal to the average particle diameter of the resin particles was 0.005.

Example 12:
In the obtained resin particles, the content of carbon nanotubes was 48 parts by weight with respect to 100 parts by weight of the resin. In the obtained particle composite, the content of the catalyst metal was 36 parts by weight with respect to 100 parts by weight of the resin particles. The ratio of the average major axis of the catalyst metal to the average particle diameter of the resin particles was 0.005.

(Comparative Example 1)
Production of electrode material:
3.5 g of carbon particles (commercial product: average particle size 2.2 μm, CV value 48.6%, aspect ratio 8.2) was added to 1 L of pure water and dispersed to obtain a dispersion. To the resulting dispersion, a heminminedinitroplatinum (II) nitric acid solution containing 0.5 g of platinum metal was added and sufficiently blended with the carbon particles to obtain a suspension (1). A 10% aqueous ammonia solution was added to the suspension (1) to adjust the pH to 8.5. Thereafter, a 28% ammonia solution as a hydroxide forming alkali solution was added at a dropping rate of 0.1 ml / min. It was dripped at. During the dropwise addition of the hydroxide-forming alkaline solution, the generated platinum hydroxide was adhered to the carbon particles while being dispersed by ultrasonic stirring to obtain a suspension (2).

  Thereafter, the suspension (2) was filtered to take out the powder, and the obtained powder was vacuum dried at 130 ° C. for 24 hours. Next, it reduced at 450 degreeC hold | maintained for 10 hours in hydrogen gas atmosphere, and obtained the carbon particle. The rate of temperature increase during the reduction treatment was 10 ° C./min. Using the obtained carbon particles, an electrode material (a plurality of particle composites) and an electrode were produced in the same manner as in Example 1.

(Comparative Example 2)
(1) Production of resin particles Carbon resin particles using carbon black were produced as follows.

  1 part by weight of tetramethylol methane triacrylate and 99 parts by weight of acrylonitrile were mixed uniformly, and 5 parts by weight of carbon black was further added. Thereafter, carbon black having a surface coated for 48 hours was uniformly dispersed using a bead mill to obtain a polymerizable monomer composition.

  To the obtained polymerizable monomer composition, 2 parts by weight of benzoyl peroxide was uniformly mixed to obtain a mixed solution. The above mixed solution was put into 850 parts by weight of a 3% strength by weight aqueous polyvinyl alcohol solution and well stirred. Thereafter, the colored polymerizable monomer droplets were suspended with a homogenizer so that the particle diameter was about 0.5 to 5.0 μm, and a suspension was obtained.

  The obtained suspension was transferred to a 2 liter separable flask equipped with a thermometer, a stirrer and a reflux condenser, heated to 85 ° C. with stirring in a nitrogen atmosphere, and subjected to a polymerization reaction for 7 hours. Further, the temperature was raised to 90 ° C. and maintained for 3 hours to complete the polymerization reaction to obtain a polymerization reaction solution. Thereafter, the polymerization reaction liquid was cooled, and the produced resin particles were filtered, sufficiently washed with water and dried to obtain 120 parts by weight of particles having a particle diameter of 2.5 μm. The obtained particles were classified to obtain resin particles.

  Using the obtained resin particles, an electrode material (a plurality of particle composites) and an electrode were produced in the same manner as in Example 1.

  In the obtained resin particles, the carbon black content was 5 parts by weight with respect to 100 parts by weight of the resin. In the obtained particle composite, the content of the catalyst metal was 36 parts by weight with respect to 100 parts by weight of the resin particles. The ratio of the average long diameter of the catalyst metal to the average particle diameter of the resin particles was 0.009.

(Evaluation)
(1) Resistivity of resin particles and particle composites The resistivity of resin particles and particle composites was determined by measuring the powder compression resistance.

  The resin particles and the particle composite are placed in a cylindrical container (diameter 20 mm, vertical length 50 mm), and then the resin particles and the particle composite are put into a pressure cell with a load cell with a pressure of 63.7 MPa, A compressive load of 20 kN was applied in the vertical direction. And DC resistance was measured using the low resistivity meter (Model MCP-T610: Mitsubishi Chemical Analytech Co., Ltd.), and the resistivity was computed by the following formula. The smaller the resistivity, the better the conductivity.

  Resistivity = measured value × cross-sectional area of resin particle or particle composite in cylindrical container / thickness of resin particle or particle composite

(2) Compression elastic modulus (10% K value) of resin particles and particle composite
Using the above-described compression elastic modulus (10% K value) of the resin particles and the particle composite, using a micro-compression tester (“Fischer Scope H-100” manufactured by Fischer) under the condition of 23 ° C. Measured.

(3) Evaluation of power generation efficiency (stress relaxation) and oxidation resistance In a fuel cell including a first electrode and a second electrode (a fuel electrode and an air electrode) and an electrolyte, the obtained electrode is used as the first electrode. And used as the second electrode. The obtained fuel cell was operated at 80 ° C. for 4000 hours.

  The retention rate of power generation efficiency after the start of operation relative to the power generation efficiency at the start of operation was evaluated. Based on Comparative Example 1, the determination was made according to the following criteria.

○: Retention rate is higher than Comparative Example 1 Δ: Retention rate is lower than Comparative Example 1, but the retention rate is maintained at 80% or higher ×: Retention rate is lower than Comparative Example 1 and retention rate Is less than 80%

  Moreover, the retention rate of the porosity of the electrode after the operation with respect to the porosity of the electrode before the operation was evaluated. Based on Comparative Example 1, the determination was made according to the following criteria.

○: Retention rate is higher than Comparative Example 1 Δ: Retention rate is lower than Comparative Example 1, but the retention rate is maintained at 80% or higher ×: Retention rate is lower than Comparative Example 1 and retention rate Is less than 80%

DESCRIPTION OF SYMBOLS 1 ... Particle complex 11 ... Resin particle 12 ... Catalyst metal

Claims (10)

Including resin particles and catalytic metal,
The electrode material whose resistivity of the said resin particle is 1000 ohm * cm or less. The electrode material according to claim 1, wherein a compression elastic modulus when the resin particles are compressed by 10% is 100 N / mm ² or more.   The electrode material according to claim 1, wherein the catalyst metal is supported on the resin particles. The electrode material according to claim 3, wherein a compression elastic modulus when a particle composite in which the catalyst metal is supported on the resin particles is compressed by 10% is 100 N / mm ² or more.   The electrode material according to claim 1, wherein the resin particles contain carbon.   The electrode material according to claim 1, wherein the resin particles include carbon black, graphite, graphitized carbon, boron carbide, carbon nanotubes, diamond, fullerene, or graphene.   The electrode material according to any one of claims 1 to 6, wherein an aspect ratio of the resin particles is 5 or less.   The electrode material according to claim 1, comprising carbon particles.   The electrode material according to claim 1, which is used for forming a fuel cell electrode.   The electrode formed with the electrode material of any one of Claims 1-9.

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