JP2021027048A - Membrane-electrode assembly for fuel battery, and solid polymer fuel battery - Google Patents

Abstract

To provide a membrane-electrode assembly for a fuel battery, which has an electrode catalyst layer showing a high power generation characteristic.SOLUTION: A membrane-electrode assembly for a fuel battery comprises: a polymer electrolyte membrane; and a pair of electrode catalyst layers holding the polymer electrolyte membrane therebetween. At least one of the pair of electrode catalyst layers includes: a particle which supports a catalyst comprising a noble metal component; a polyelectrolyte; and a fibrous oxide catalyst material. The fibrous oxide catalyst material includes at least one transition metal element selected from a group consisting of Ta, Nb, Ti and Zr.SELECTED DRAWING: Figure 1

Description

The present invention relates to a membrane electrode assembly for a fuel cell and a polymer electrolyte fuel cell.

A fuel cell is a power generation system that uses a fuel gas containing hydrogen and an oxidant gas containing oxygen to cause an inverse reaction of electrolysis of water at an electrode containing a catalyst to generate electricity at the same time as heat. This power generation system has features such as high efficiency, low environmental load, and low noise as compared with the conventional power generation method, and is attracting attention as a clean energy source in the future. There are several types of fuel cells depending on the type of ionic conductor used in the fuel cell, and a fuel cell using a proton conductive polymer membrane is called a polymer electrolyte fuel cell.

Among fuel cells, polymer electrolyte fuel cells can be used near room temperature, and are expected to be used as in-vehicle power supplies and household stationary power supplies. In recent years, various research and development have been carried out. ing. A polymer electrolyte fuel cell is a battery in which a membrane electrode assembly (Membrane Electrode Assembly: hereinafter, sometimes referred to as MEA) in which an electrode catalyst layer is arranged on each surface of a polymer electrolyte membrane is sandwiched between a pair of separators. Is.

One separator has a gas flow path for supplying a fuel gas containing hydrogen to one of the electrodes, and the other separator has an oxidizing agent gas containing oxygen to the other of the electrodes. Gas flow path is formed.

Here, the above-mentioned one electrode to which the fuel gas is supplied is referred to as a fuel electrode, and the above-mentioned other electrode to which the oxidant gas is supplied is referred to as an air electrode. These electrodes include an electrode catalyst layer having carbon particles (catalyst-supported particles) carrying a catalyst such as a polymer electrolyte and a platinum-based noble metal, and a gas diffusion layer having both gas permeability and electron conductivity. There is. The gas diffusion layer constituting these electrodes is arranged so as to face the separator, that is, between the electrode catalyst layer and the separator.

For the electrode catalyst layer, efforts have been made to increase the gas diffusivity in order to improve the output density of the fuel cell. One of them relates to the pores in the electrode catalyst layer. The pores in the electrode catalyst layer are located ahead of the separator through the gas diffusion layer and serve as a passage for transporting a plurality of substances. At the fuel electrode, the pores not only smoothly supply the fuel gas to the three-phase interface, which is the reaction field for redox, but also supply water for smoothly conducting the generated protons in the polymer electrolyte membrane. Fulfill function. At the air electrode, the pores serve to smoothly remove water generated by the electrode reaction as well as supply the oxidant gas.

Expensive platinum is used as an electrode catalyst in current polymer electrolyte fuel cells, and the development of alternative materials is strongly required for full-scale spread. In particular, since the air electrode uses more platinum than the fuel electrode, the development of a platinum alternative material (non-platinum catalyst) showing high oxygen reduction catalytic ability at the air electrode is active.

As an example of a non-platinum catalyst in an air electrode, for example, Patent Document 1 describes a mixture of a transition metal, an iron nitride and a noble metal. Further, Patent Document 2 describes a nitride of molybdenum, which is a transition metal. However, the catalytic substance as described in Patent Document 1 and Patent Document 2 may have insufficient oxygen reducing ability in the acidic electrolyte, and the catalytic substance may dissolve.

Japanese Unexamined Patent Publication No. 2005-44659 Japanese Unexamined Patent Publication No. 2005-63677

An object of the present invention is to provide a membrane electrode assembly for a fuel cell having an electrode catalyst layer exhibiting high power generation characteristics when used in a polymer electrolyte fuel cell.

The fuel cell membrane electrode joint that solves the above problems includes a polymer electrolyte membrane and a pair of electrode catalyst layers that sandwich the polymer electrolyte membrane, and at least one of the pair of electrode catalyst layers is a noble metal. The fibrous oxide-based catalyst substance contains a catalyst-supporting particle composed of components, a polymer electrolyte, and a fibrous oxide-based catalyst substance, and the fibrous oxide-based catalyst substance is an electrode for an oxygen reduction electrode used as a positive electrode of a fuel cell. It is an active material and is characterized by containing at least one transition metal element selected from Ta, Nb, Ti, and Zr.

According to the present invention, it is possible to provide an electrode catalyst layer exhibiting high power generation characteristics when used in a polymer electrolyte fuel cell.

The exploded perspective view which shows typically the structure of the membrane electrode assembly which has the electrode catalyst layer for a fuel cell in the membrane electrode assembly for fuel cell of one Embodiment. The exploded perspective view which shows typically the structure of the polymer electrolyte fuel cell provided with the membrane electrode assembly of FIG.

Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings.
Here, the drawings are schematic, and the relationship between the thickness and the plane dimension, the ratio of the thickness of each layer, and the like are different from the actual ones. Further, the embodiments shown below exemplify a configuration for embodying the technical idea of the present disclosure, and the technical idea of the present disclosure describes the materials, shapes, structures, etc. of the components as follows. It is not specific to anything. The technical idea of the present disclosure may be modified in various ways within the technical scope specified by the claims stated in the claims.

[Membrane electrode assembly]
As shown in FIG. 1, the membrane electrode assembly 11 of the present embodiment includes a polymer electrolyte membrane 1 and a pair of electrode catalyst layers 2 and 3 that sandwich the polymer electrolyte membrane 1 from above and below.

Further, each of the electrode catalyst layers 2 and 3 includes particles carrying a catalyst composed of at least a noble metal component and a polymer electrolyte. At least one of the pair of electrode catalyst layers 2 and 3 (hereinafter, also referred to as a first electrode catalyst layer) has a fibrous oxide-based catalyst substance.

The fibrous oxide-based catalyst substance contained in the first electrode catalyst layer contains at least one transition metal element selected from the group composed of Ta, Nb, Ti, and Zr. The oxide-based catalyst substance is preferably a partially oxidized nitride having P introduced as a substituent atom, and more preferably Ti as the transition metal element. That is, the oxide-based catalyst substance is composed of a substance in which a part of the nitride of the transition metal element containing P which is a substitution atom is oxidized.

In the fibrous oxide-based catalyst substance, it is preferable that the average fiber diameter is contained in the range of 20 nm or more and 1 μm or less, and the average fiber length is contained in the range of 1.2 μm or more and 30 μm or less. In the fibrous oxide-based catalyst substance, it is more preferable that the average fiber diameter is contained in the range of 80 nm or more and 200 nm or less, and the average fiber length is contained in the range of 10 μm or more and 20 μm or less.

In the first electrode catalyst layer, the ratio (MB / MA) of the mass (MB) of the fibrous oxide-based catalyst substance to the mass (MA) of the carrier in the particles carrying the catalyst is 0.1 times or more and 10 times. It is preferably 0.5 times or more, and more preferably 3 times or less.

In the first electrode catalyst layer, the ratio (MC / MA) of the mass (MC) of the polymer electrolyte to the mass (MA) of the carrier in the catalyst-supporting particles is 0.1 times or more and 1.4 times or less. It is preferably 0.5 times or more and 1.0 times or less, more preferably.

In the first electrode catalyst layer, the particles carrying the catalyst composed of the noble metal component are preferably covered with a hydrophobic film.

The inventor of the present application has confirmed that the first electrode catalyst layer having the following structure has drainage properties. The detailed mechanism by which the first electrode catalyst layer has drainage is presumed as follows. The present invention is not bound by the following mechanism.

In the first electrode catalyst layer, it is possible to suppress the occurrence of cracks in the electrode catalyst layer, which reduces the durability of the first electrode catalyst layer, by entwining the fibrous oxide-based catalyst substances. As a result, a first electrode catalyst layer having high durability and mechanical properties can be obtained. Further, pores are formed in the electrode catalyst layer by the entanglement of the particles carrying the catalyst composed of the noble metal component and the fibrous oxide-based catalyst substance. When the polymer electrolyte fuel cell provided with the first electrode catalyst layer is driven in a high current range, the water generated by the electrode reaction can be discharged by the pores, and the diffusibility of the reaction gas is enhanced. Is presumed to be possible. On the other hand, when a non-fibrous oxide-based catalyst substance is used, pores are less likely to be formed in the electrode catalyst layer because there is no entanglement between the particles carrying the catalyst composed of the noble metal component and the oxide-based catalyst substance. Therefore, it is difficult to discharge the water generated by the electrode reaction, and as a result, when the polymer electrolyte fuel cell provided with the electrode catalyst layer is driven in a high current range, the diffusibility of the reaction gas can be improved. It is estimated that it cannot be done.

When the average fiber diameter of the fibrous oxide-based catalyst substance is less than 20 nm, it is presumed that pores may not be easily formed in the electrode catalyst layer due to the strong flexibility of the oxide-based catalyst substance. .. That is, when the average fiber diameter of the oxide-based catalyst substance is 20 nm or less, it is possible to prevent the oxide-based catalyst substance from becoming excessively flexible. This facilitates the formation of pores in the electrode catalyst layer.

Further, when the average fiber diameter of the fibrous oxide-based catalyst substance exceeds 1 μm, it is presumed that the oxide-based catalyst substance may not be dispersed as an ink due to the strong influence of the straightness of the oxide-based catalyst substance. That is, when the average fiber diameter of the oxide-based catalyst substance is 1 μm or less, it is possible to prevent the oxide-based catalyst substance from becoming excessively straight. As a result, the oxide-based catalyst substance is easily dispersed in the ink for forming the electrode catalyst layer.

If the average fiber length of the fibrous oxide-based catalyst substance is less than 1.2 μm, it is presumed that the mechanical properties of the electrode catalyst layer may deteriorate. That is, when the average fiber length of the oxide-based catalyst substance is 1.2 μm or more, it is possible to suppress the deterioration of the mechanical properties of the electrode catalyst layer. If the average fiber length exceeds 30 μm, it is estimated that the ink may not be dispersed. That is, when the average fiber length of the oxide-based catalyst substance is 30 μm or less, the oxide-based catalyst substance is likely to be dispersed in the ink for forming the electrode catalyst layer.

When the mass of the fibrous oxide-based catalyst substance is less than 0.1 times the mass of the carrier in the catalyst-supporting particles, it is difficult to draw a sufficient current due to the influence of the small catalytic activity of the oxide-based catalyst substance. It is estimated that there are cases. That is, when the ratio of the mass of the oxide-based catalytic substance to the mass of the carrier in the particles carrying the catalyst is 0.1 times or more, the catalytic activity of the oxide-based catalytic substance is suppressed from being reduced. It is possible to generate a sufficient current.

If it exceeds 10 times, it is estimated that the current may decrease due to the thickening of the electrode catalyst layer. That is, when the ratio of the mass of the oxide-based catalyst substance to the mass of the carrier in the particles carrying the catalyst is 10 times or less, it is possible to prevent the electrode catalyst layer from becoming excessively thick, thereby reducing the current. It is possible to suppress.

If the mass of the polymer electrolyte is less than 0.1 times the mass of the carrier in the catalyst-supporting particles, it may be difficult to draw a sufficient current due to the effect of lowering the proton conductivity of the electrode catalyst layer. Inferred. That is, when the ratio of the mass of the oxide-based catalyst substance to the mass of the carrier in the particles carrying the catalyst is 0.1 times or more, the decrease in proton conductivity of the electrode catalyst tank is suppressed, thereby suppressing the decrease. , It is possible to generate a sufficient current.

If it exceeds 1.4 times, it is presumed that the diffusibility of the reaction gas may not be enhanced due to the effect of reducing the pores formed in the electrode catalyst layer. That is, the ratio of the mass of the oxide-based catalyst substance to the mass of the carrier in the particles carrying the catalyst is 1.4 times or less, thereby suppressing the decrease of pores in the electrode catalyst tank, thereby suppressing the decrease of the reaction gas. It is possible to increase the diffusivity.

According to the membrane electrode assembly 11 of the present embodiment, unlike the case where the drainage property is improved by changing the configuration of the electrode catalyst layer as in the conventional case, the power generation characteristic is not deteriorated due to the increase in the interface resistance. As a result, according to the polymer electrolyte fuel cell provided with the membrane electrode assembly 11, in the high current region where a large amount of generated water is generated, as compared with the conventional polymer electrolyte fuel cell provided with the membrane electrode assembly. The power generation characteristics of the

[Proton electrolyte fuel cell]
Next, the polymer electrolyte fuel cell provided with the membrane electrode assembly 11 of the embodiment will be described with reference to FIG.

The polymer electrolyte fuel cell 12 shown in FIG. 2 includes a pair of gas diffusion layers 4 and 5. The gas diffusion layer 4 is arranged so as to face the electrode catalyst layer 2 of the membrane electrode assembly 11. The gas diffusion layer 5 is arranged so as to face the electrode catalyst layer 3. An air electrode (cathode, positive electrode) 6 is formed by the electrode catalyst layer 2 and the gas diffusion layer 4. The fuel electrode (anode, negative electrode) 7 is formed by the electrode catalyst layer 3 and the gas diffusion layer 5.

Further, a set of separators 10a and 10b are arranged outside the gas diffusion layers 4 and 5, respectively. That is, the membrane electrode assembly 11 is sandwiched between the separators 10a and 10b in the thickness direction of the membrane electrode assembly 11. The separators 10a and 10b include gas flow paths 8a and 8b for gas flow and cooling water flow paths 9a and 9b for cooling water flow. The separators 10a and 10b are made of a conductive and impermeable material.

For example, hydrogen gas is supplied as a fuel gas to the gas flow path 8b of the separator 10b facing the fuel electrode 7. On the other hand, for example, oxygen gas is supplied as an oxidizing agent gas to the gas flow path 8a of the separator 10a facing the air electrode 6. An electromotive force can be generated between the fuel electrode 7 and the air electrode 6 by causing an electrode reaction between hydrogen as a fuel gas and oxygen as an oxidant gas in the presence of a catalyst.

In the polymer electrolyte fuel cell 12, a pair of separators 10a and 10b sandwich a polymer electrolyte membrane 1, a pair of electrode catalyst layers 2 and 3, and a pair of gas diffusion layers 4 and 5. The polymer electrolyte fuel cell 12 shown in FIG. 2 is an example of a fuel cell having a single cell structure, but in the polymer electrolyte fuel cell, a plurality of cells are laminated via a separator 10a or a separator 10b. It may have a structure.

[Manufacturing method of electrode catalyst layer]
Next, an example of the method for manufacturing the first electrode catalyst layer will be described.
The first electrode catalyst layer is manufactured by a method including the following first step and second step. The first step is a step of producing a catalyst ink containing catalyst-supporting particles, an oxide-based catalyst substance, a polymer electrolyte, and a solvent. The second step is a step of forming the first electrode catalyst layer by applying the catalyst ink obtained in the first step onto the substrate and drying the solvent. An electrode catalyst layer other than the first electrode catalyst layer, that is, a second electrode catalyst layer may be manufactured by the same step. However, the second electrode catalyst layer does not contain the fibrous oxide-based catalyst substance contained in the first electrode catalyst layer. Then, the membrane electrode assembly 11 is obtained by attaching the produced pair of electrode catalyst layers 2 and 3 to the opposing surfaces of the polymer electrolyte membrane 1.

[Details]
Hereinafter, the membrane electrode assembly 11 and the polymer electrolyte fuel cell 12 will be described in more detail.
The polymer electrolyte membrane 1 may be any one having proton conductivity, and for example, a fluorine-based polymer electrolyte membrane or a hydrocarbon-based polymer electrolyte membrane can be used. Examples of the fluorine-based polymer electrolyte membrane include Nafion (registered trademark) manufactured by DuPont, Flemion (registered trademark) manufactured by Asahi Glass Co., Ltd., AGClex (registered trademark) manufactured by Asahi Kasei Corporation, and Gore Select (registered trademark) manufactured by Gore Co., Ltd. Etc. can be used.

Examples of the hydrocarbon-based polymer electrolyte membrane include sulfonated polyetherketone.
Electrolyte films such as sulfonated polyether sulfone, sulfonated polyether ether sulfone, sulfonated polysulfide, and sulfonated polyphenylene can be used. In particular, it is preferable to use a Nafion (registered trademark) -based material manufactured by DuPont as the polymer electrolyte membrane 1.

The electrode catalyst layers 2 and 3 are formed on both surfaces of the polymer electrolyte membrane 1 using catalyst ink. The catalyst ink for the electrode catalyst layers 2 and 3 contains particles carrying a catalyst, a polymer electrolyte, and a solvent. Further, the catalyst ink for the first electrode catalyst layer contains catalyst-supporting particles, an oxide-based catalyst substance, a polymer electrolyte, and a solvent.

The polymer electrolyte contained in the catalyst ink may be any one having proton conductivity. As the polymer electrolyte, the same material as that of the polymer electrolyte membrane 1 can be used. As the polymer electrolyte, for example, a fluorine-based polymer electrolyte or a hydrocarbon-based polymer electrolyte can be used. As the fluorine-based polymer electrolyte, for example, Nafion (registered trademark) -based material manufactured by DuPont can be used. Further, as the hydrocarbon-based polymer electrolyte, for example, an electrolyte such as a sulfonated polyether ketone, a sulfonated polyether sulfone, a sulfonated polyether ether sulfone, a sulfonated polysulfide, or a sulfonated polyphenylene can be used. In particular, it is preferable to use a Nafion (registered trademark) -based material manufactured by DuPont as the fluorine-based polymer electrolyte.

As the catalyst composed of the noble metal component used in the present embodiment, for example, a metal or alloy, a metal oxide, a metal compound oxide, or the like can be used. Examples of the metal include one or more metals selected from the group composed of platinum, palladium, ruthenium, iridium, and rhodium. The compound oxide referred to here is an oxide composed of two types of metals.

The average particle size of the catalyst described above is preferably contained in the range of 0.5 nm or more and 20 nm or less, and more preferably in the range of 1 nm or more and 5 nm or less. Here, the average particle size is an average particle size obtained by an X-ray diffraction method for a particle carrying a catalyst including a carrier such as carbon particles and a catalyst supported on the carrier. Further, in the case of a catalyst not supported on a carrier, it is the arithmetic mean particle size obtained from the particle size measurement. When the average particle size of the catalyst particles is contained in the range of 0.5 nm or more and 20 nm or less, the activity and stability of the catalyst are improved, which is preferable.

Carbon particles are generally used as the electron-conducting powder carrying the above-mentioned catalyst, that is, the carrier. The type of carbon particles is not limited as long as it is fine particles, has conductivity, and is not affected by a catalyst. As the carbon particles, for example, carbon black, graphite, activated carbon, carbon fiber, carbon nanotubes, and fullerenes can be used.

The average particle size of the carbon particles is preferably contained in the range of 10 nm or more and 1000 nm or less, and more preferably contained in the range of 10 nm or more and 100 nm or less. Here, the average particle size is the average particle size obtained from the SEM image. When the average particle size of the carbon particles is contained in the range of 10 nm or more and 1000 nm or less, the activity and stability of the catalyst are improved, which is preferable. Further, when the average particle size of the carbon particles is included in the range of 10 nm or more and 1000 nm or less, an electron conduction path is likely to be formed, and the gas diffusivity and the utilization rate of the catalyst of the two electrode catalyst layers 2 and 3 are likely to be formed. Is preferable because it improves.

The catalyst-supporting particles described above may have a hydrophobic coating. In other words, the particles carrying the catalyst may be covered with a hydrophobic coating. In this case, the hydrophobic coating preferably has a film thickness that allows the reaction gas to sufficiently permeate. Specifically, the film thickness of the hydrophobic film is preferably 40 nm or less. If it is thicker than this, the supply of the reaction gas to the active site may be hindered. On the other hand, if the hydrophobic coating is 40 nm or less, the reaction gas sufficiently permeates the hydrophobic coating, so that the catalyst-supported particles can be imparted with hydrophobicity.

Further, the film thickness of the hydrophobic film covering the catalyst-supporting particles is preferably a film thickness that sufficiently repels the generated water. Specifically, the film thickness of the hydrophobic film is preferably 2 nm or more. If the hydrophobic film becomes thinner than this, the generated water may stay and the supply of the reaction gas to the active site may be hindered. That is, when the hydrophobic film has a thickness of 2 nm or more, the retention of the produced water is suppressed, and thereby the supply of the reaction gas to the active site is suppressed.

The hydrophobic film covering the catalyst-supported particles is formed, for example, from a fluorine-based compound having at least one polar group. Examples of the polar group include a hydroxyl group, an alkoxy group, a carboxyl group, an ester group, an ether group, a carbonate group and an amide group. Due to the presence of the polar group, the fluorine-based compound can be immobilized on the outermost surface of the electrode catalyst layer. The portion of the fluorine-based compound other than the polar group preferably has a structure composed of fluorine and carbon because of its high hydrophobicity and chemical stability. However, it is not limited to such a structure as long as the hydrophobic film has sufficient hydrophobicity and chemical stability.

In the present disclosure, as the oxide-based catalyst substance, a substance containing at least one selected from the group composed of Ta, Nb, Ti, and Zr can be used. The oxide-based catalyst substance is preferably used as a substitute material for platinum in the electrode catalyst layer provided in the air electrode, that is, the positive electrode.

Further, more preferably, a substance in which P is introduced as a substitution atom into the nitride of these transition metal elements and partially oxidized in an atmosphere containing oxygen can be used. That is, the oxide-based catalyst substance is a substance in which a part of the transition metal nitride containing phosphorus (P) is oxidized. In other words, oxide-based substances include transition metal atoms, nitrogen atoms, phosphorus atoms, and oxygen atoms. In the transition metal nitride, a part of the transition metal atom is replaced with a phosphorus atom.

Specifically, it is a substance (TiONP) in which a nitride (TiNP) of Ti having P introduced as a substitution atom is partially oxidized in an atmosphere containing oxygen. In this case, in the titanium nitride (TiN), a part of the titanium atom is replaced with a phosphorus atom. In addition, a part of titanium nitride is oxidized.

The solvent used as the dispersion medium for the catalyst ink is one that can dissolve the polymer electrolyte in a highly fluid state or disperse it as a fine gel without eroding the catalyst-supporting particles, the oxide-based catalyst substance, and the polymer electrolyte. If there is, it is not particularly limited. However, it is desirable that the solvent contains at least a volatile organic solvent. The solvent used as the dispersion medium of the catalyst ink may be alcohols, ketone solvents, ether solvents, polar solvents and the like. The alcohols may be, for example, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutyl alcohol, tert-butyl alcohol, pentanol and the like. The ketone solvent may be, for example, acetone, methyl ethyl ketone, pentanone, methyl isobutyl ketone, heptanone, cyclohexanone, methylcyclohexanone, acetonyl acetone, diisobutyl ketone and the like. The ether solvent may be, for example, tetrahydrofuran, dioxane, diethylene glycol dimethyl ether, anisole, methoxytoluene, dibutyl ether and the like. The polar solvent may be, for example, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, ethylene glycol, diethylene glycol, diacetone alcohol, 1-methoxy-2-propanol and the like. Further, the solvent may be a mixed solvent in which two or more of the above-mentioned materials are mixed.

Further, since the dispersion medium using the lower alcohol has a high risk of ignition, when the lower alcohol is used as the dispersion medium, it is preferable to use a mixed solvent of the lower alcohol and water. Further, the dispersion medium may contain water that is familiar with the polymer electrolyte, that is, water that has a high affinity for the polymer electrolyte. The amount of water added to the dispersion medium is not particularly limited as long as the polymer electrolyte does not separate and cause cloudiness or gelation.

In order to disperse the catalyst-supported particles in the catalyst ink, the catalyst ink may contain a dispersant. Examples of the dispersant include anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants and the like.

Examples of anionic surfactants include alkyl ether carboxylate, ether carboxylate, alkanoyl zarcosine, alkanoyl glutamate, acyl glutamate, oleic acid / N-methyl taurine, potassium oleate / diethanolamine salt, alkyl ether sulfate tri. Ethanolamine salt, polyoxyethylene alkyl ether sulfate triethanolamine salt, amine salt of special modified polyether ester acid, amine salt of higher fatty acid derivative, amine salt of special modified polyester acid, amine salt of high molecular weight polyether ester acid , Special modified phosphoric acid ester amine salt, high molecular weight polyesteric acid amidamine salt, special fatty acid derivative amidamine salt, higher fatty acid alkylamine salt, high molecular weight polycarboxylic acid amidamine salt, sodium laurate, sodium stearate, oleic acid Carboxylic acid type surfactants such as sodium, dialkyl sulfosuccinate, dialkyl sulfosuccinate, 1,2-bis (alkoxycarbonyl) -1-ethanesulfonate, alkylsulfonate, paraffin sulfonate, α-olefin Sulfonate, linear alkylbenzene sulfonate, alkylbenzene sulfonate, polynaphthylmethane sulfonate, naphthalene sulfonate-formalin condensate, alkylnaphthalene sulfonate, alkanoylmethyl tauride, lauryl sulfate sodium salt, cetyl sulfate sodium salt, stearyl sulfate sodium salt , Sulfonic acid type surfactants such as oleyl sulfate sodium salt, lauryl ether sulfate ester salt, sodium alkylbenzene sulfonate, oil-soluble alkylbenzene sulfonate, α-olefin sulfonate, alkyl sulfate ester salt, alkyl sulfate, alkyl Sulfate, alkyl ether sulfate, polyoxyethylene alkyl ether sulfate, alkyl polyethoxysulfate, polyglycol ether sulfate, alkyl polyoxyethylene sulfate, sulfated oil, highly sulfated oil and other sulfate ester type surfactants, phosphoric acid (Mono or di) alkyl salt, (mono or di) alkyl phosphate, (mono or di) alkyl phosphate ester salt, alkyl polyoxyethylene phosphate salt, alkyl ether phosphate, alkyl polyethoxy phosphate, polyoxyethylene Alkyl ether, al-phosphate Kilphenyl polyoxyethylene salt, alkylphenyl ether phosphate, alkylphenyl polyethoxy phosphate, polyoxyethylene alkylphenyl ether phosphate, higher alcohol phosphate monoester disodium salt, higher alcohol phosphate diester disodium salt , Phosphate ester type surfactants such as zinc dialkyldithiophosphate and the like.

Examples of cationic surfactants are benzyldimethyl {2- [2- (P-1,1,3,3-tetramethylbutylphenoxy) ethoxy] ethyl} ammonium chloride, octadecylamine acetate, tetradecylamine acetate. , Octadecyltrimethylammonium chloride, beef trimethylammonium chloride, dodecyltrimethylammonium chloride, palm trimethylammonium chloride, hexadecyltrimethylammonium chloride, behenyltrimethylammonium chloride, palm dimethylbenzylammonium chloride, tetradecyldimethylbenzylammonium chloride, octadecyldimethylbenzylammonium chloride , Dioleyl dimethylammonium chloride, 1-hydroxyethyl-2-beef imidazoline quaternary salt, 2-heptadecenyl-hydroxyethyl imidazoline, stearamide ethyldiethylamine acetate, stearamide ethyldiethylamine hydrochloride, triethanolamine monostearate Examples thereof include formates, alkylpyridium salts, higher alkylamine ethylene oxide adducts, polyacrylamideamine salts, modified polyacrylamideamine salts, and perfluoroalkyl quaternary ammonium iodide.

Examples of amphoteric tensides include dimethyl coconut betaine, dimethyl lauryl betaine, sodium lauryl aminoethylglycine, sodium lauryl aminopropionate, stearyl dimethyl betaine, lauryl dihydroxyethyl betaine, amide betaine, imidazolinium betaine, lecithin, 3-[ ω-fluoroalkanoyl-N-ethylamino]
Examples thereof include sodium -1-propanesulfonate, N- [3- (perfluorooctane sulfonamide) propyl] -N, N-dimethyl-N-carboxymethylene ammonium betaine and the like.

Examples of nonionic surfactants are coconut fatty acid diethanolamide (1: 2 type), coconut fatty acid diethanolamide (1: 1 type), bovine fatty acid diethanolamide (1: 2 type), bovine fatty acid diethanolamide (1: 1 type). Type), oleate diethanolamide (1: 1 type), hydroxyethyl laurylamine, polyethylene glycol laurylamine, polyethylene glycol palmamine, polyethylene glycol stearylamine, polyethylene glycol beef fat amine, polyethylene glycol beef fat propylenediamine, polyethylene glycol dioleylamine, Dimethyllaurylamine oxide, dimethylstearylamine oxide, dihydroxyethyllaurylamine oxide, perfluoroalkylamine oxide, polyvinylpyrrolidone, higher alcohol ethylene oxide adduct, alkylphenol ethylene oxide adduct, fatty acid ethylene oxide adduct, polypropylene glycol ethylene oxide adduct , Glycerin fatty acid ester, pentaerythlit fatty acid ester, sorbit fatty acid ester, sorbitan fatty acid ester, sugar fatty acid ester and the like.

Among the above-mentioned surfactants, sulfonic acid type surfactants such as alkylbenzene sulfonic acid, oil-soluble alkylbenzene sulfonic acid, α-olefin sulfonic acid, sodium alkylbenzene sulfonate, oil-soluble alkylbenzene sulfonate, α-olefin sulfonate, etc. The agent is suitable as a dispersant from the viewpoints of carbon dispersion effect, change in catalytic performance due to residual dispersant, and the like.

Increasing the amount of polymer electrolyte in the catalyst ink generally reduces the pore volume. On the other hand, when the amount of carbon particles in the catalyst ink is increased, the pore volume becomes large. Also, when a dispersant is used, the pore volume becomes smaller.

Further, the catalyst ink may be subjected to a dispersion treatment if necessary. The viscosity of the catalyst ink and the size of the particles contained in the catalyst ink can be controlled by the conditions of the dispersion treatment of the catalyst ink. The distributed processing can be performed by adopting various devices. In particular, the method of distributed processing is not limited. For example, examples of the dispersion treatment include treatment with a ball mill and a roll mill, treatment with a shear mill, treatment with a wet mill, ultrasonic dispersion treatment, and the like. Further, a homogenizer or the like that agitates by centrifugal force may be adopted for the dispersion treatment. As the dispersion time for performing the dispersion treatment on the catalyst ink becomes longer, the agglomerates of the catalyst-supporting particles are destroyed, so that the pore volume becomes smaller in the electrode catalyst layer formed by using the catalyst ink.

If the solid content in the catalyst ink is too high, the viscosity of the catalyst ink becomes high, so that the surfaces of the electrode catalyst layers 2 and 3 are likely to be cracked. On the other hand, if the solid content in the catalyst ink is too small, the film formation rate is very slow and the productivity is lowered. Therefore, the solid content in the catalyst ink is preferably 1% by mass (wt%) or more and 50% by mass or less. That is, when the solid content in the catalyst ink is 1% by mass or more, it is possible to prevent the film formation rate from becoming excessively slow, thereby suppressing a decrease in productivity. When the solid content in the catalyst ink is 50% by mass or less, it is possible to prevent the viscosity of the catalyst ink from becoming excessively high, thereby suppressing cracks on the surfaces of the electrode catalyst layers 2 and 3. ..

The solid content in the catalyst ink is composed of catalyst-supporting particles, an oxide-based catalyst substance, and a polymer electrolyte. When the contents of the catalyst-supporting particles and the oxide-based catalyst substance are increased in the solid content, the viscosity becomes higher than that in the case where the content of the polymer electrolyte is higher even if the solid content is the same. On the other hand, when the contents of the catalyst-supporting particles and the oxide-based catalyst substance are reduced in the solid content, the viscosity is lower than that in the case where the content of the polymer electrolyte is smaller even if the solid content is the same. Become. Therefore, the ratio of the catalyst-supporting particles and the oxide-based catalyst substance to the solid content is preferably 10% by mass or more and 80% by mass or less. The viscosity of the catalyst ink is preferably about 0.1 cP or more and 500 cP or less (0.0001 Pa · s or more and 0.5 Pa · s or less), and 5 cP or more and 100 cP or less (0.005 Pa · s or more and 0.1 Pa · s or less). s or less) is more preferable. Further, the viscosity of the catalyst ink can be controlled by adding a dispersant when the catalyst ink is dispersed.

Further, the catalyst ink may contain a pore-forming agent. According to the pore-forming agent, pores can be formed in the electrode catalyst layer by removing the pore-forming agent after the formation of the electrode catalyst layer. Examples of the pore-forming agent include acids, alkalis, substances that dissolve in water, substances that sublimate such as camphor, and substances that thermally decompose. For example, if the pore-forming agent is a substance that dissolves in warm water, the pore-forming agent may be removed from the electrode catalyst layer by water generated during power generation of the polymer electrolyte fuel cell provided with the electrode catalyst layer.

Examples of pore-forming agents that are soluble in acids, alkalis, and water include acid-soluble inorganic salts, inorganic salts that are soluble in alkaline aqueous solutions, metals that are soluble in acids or alkalis, water-soluble inorganic salts, and water-soluble organic compounds. Be done. Examples of acid-soluble inorganic salts include calcium carbonate, barium carbonate, magnesium carbonate, magnesium sulfate, magnesium oxide and the like. Examples of inorganic salts soluble in an alkaline aqueous solution include alumina, silica gel, and silica sol. Examples of metals soluble in acid or alkali include aluminum, zinc, tin, nickel, iron and the like. Examples of the water-soluble inorganic salts include sodium chloride, potassium chloride, ammonium chloride, sodium carbonate, sodium sulfate, monosodium phosphate and the like. Examples of the water-soluble organic compounds include polyvinyl alcohol and polyethylene glycol.

The above-mentioned pore-forming agents may be used alone or in combination of two or more, but it is preferable to use two or more in combination.

As a coating method for coating the catalyst ink on the substrate, for example, a doctor blade method, a dipping method, a screen printing method, a roll coating method and the like can be adopted.

Examples of the base material used for producing the electrode catalyst layers 2 and 3 include a transfer sheet. The transfer sheet used as the base material may be formed of a material having a material having good transferability. A fluororesin can be used as the material for forming the transfer sheet. The fluororesins include, for example, ethylene tetrafluoroethylene copolymer (ETFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroperfluoroalkyl vinyl ether copolymer (PFA), and polytetrafluoroethylene (PFA). It may be PTFE) or the like. Further, the base material may be a polymer sheet or a polymer film. Materials for forming the polymer sheet or polymer are, for example, polyimide, polyethylene terephthalate, polyamide (nylon (registered trademark)), polysulfone, polyethersulfone, polyphenylene sulfide, polyetheretherketone, polyether. It may be imide, polyarylate, polyethylene naphthalate or the like. When a transfer sheet is used as the base material, the transfer sheet is peeled off from the electrode film after bonding the electrode film, which is a coating film from which the solvent has been removed, to both surfaces of the polymer electrolyte membrane 1. A membrane electrode assembly 11 having electrode catalyst layers 2 and 3 on both sides of the polymer electrolyte membrane 1 can be formed.

As the material for forming the gas diffusion layers 4 and 5, a material having gas diffusivity and conductivity can be used. For example, as the gas diffusion layers 4 and 5, a porous carbon material can be used. The porous carbon material may be, for example, carbon cloth, carbon paper, non-woven fabric, or the like.

As the separators 10a and 10b, carbon type or metal type separators and the like can be used. The gas diffusion layers 4 and 5 and the separators 10a and 10b may have an integral structure, respectively. That is, the gas diffusion layer 4 and the separator 10a may be integrally formed, or the gas diffusion layer 5 and the separator 10b may be integrally formed. Further, when the separators 10a and 10b or the electrode catalyst layers 2 and 3 perform the functions of the gas diffusion layers 4 and 5, the gas diffusion layers 4 and 5 may be omitted. The polymer electrolyte fuel cell 12 is manufactured by assembling accompanying devices such as a gas supply device and a cooling device (not shown).

<Action and others>
As described above, in the present embodiment, the polymer electrolyte fuel cell including the membrane electrode assembly 11 exhibiting high power generation characteristics under high humidification conditions, the method for manufacturing the membrane electrode assembly 11, and the membrane electrode assembly 11 12 is described. In the electrode catalyst layers 2 and 3 of the membrane electrode assembly 11 of the present embodiment, the occurrence of cracks in the electrode catalyst layer that causes a decrease in durability due to entanglement of fibrous oxide-based catalyst substances is suppressed. , This provides high durability and mechanical properties.

Further, pores are formed in the electrode catalyst layer by the entanglement of the catalyst-supporting particles and the fibrous oxide-based catalyst substance. Due to the pores of the electrode catalyst layer, when the polymer electrolyte fuel electrons are driven, water generated by the electrode reaction can be discharged in a high current region, and the diffusivity of the reaction gas can be enhanced.

The membrane electrode assembly produced by the method for producing an electrode catalyst layer according to the present embodiment has improved drainage in a high current region where a large amount of generated water is generated without impairing water retention under low humidification conditions. In addition, it exhibits high power generation performance and durability even under high humidification conditions. Further, the method for producing the electrode catalyst layer according to the present embodiment can efficiently and economically easily produce the membrane electrode assembly as described above, that is, at low cost.

That is, an electrode using a platinum-supported carbon catalyst (catalyst-supported particles), that is, a catalyst ink in which a platinum catalyst-supported carbon particles, a fibrous oxide-based catalyst substance, and a polymer electrolyte are dispersed in a solvent. By forming the catalyst layer, the above-mentioned film electrode junction can be produced.

Therefore, it can be manufactured without complicated manufacturing steps, and both water retention and diffusibility of the reaction gas can be improved by using the electrode catalyst layer prepared by the above procedure. Therefore, for example, the production of the electrode catalyst layer can be operated without providing a special means such as a humidifier, and as a result, the cost can be reduced.

Only one of the electrode catalyst layers 2 and 3 formed on both surfaces of the polymer electrolyte membrane 1 may be used as the first electrode catalyst layer. In that case, as described above, the first electrode catalyst layer is preferably an air electrode (cathode) in which water is generated by the electrode reaction, that is, an electrode catalyst layer forming a positive electrode.

Although the embodiments of the present disclosure have been described in detail above, the present invention is not limited to the above-described embodiments, and any changes within the scope not deviating from the gist of the present disclosure are included in the present disclosure.

Hereinafter, a method for producing the first electrode catalyst layer and the membrane electrode assembly for the polymer electrolyte fuel cell according to the present embodiment will be described with reference to specific examples and comparative examples. However, this embodiment is not limited by the following examples and comparative examples.

In the following Examples and Comparative Examples, the case where the pair of electrode catalyst layers are both used as the first electrode catalyst layer is illustrated. As described above, only one of the pair of electrode catalyst layers may be the first electrode catalyst layer.

<Example 1>
[Adjustment of catalyst ink]
A platinum-supported carbon catalyst (catalyst-supported particles) having a loading density of 50% by mass, a fibrous oxide-based catalyst substance (TiONP) having an average fiber diameter of 100 nm and an average fiber length of 15 μm, and 25 A mass% polymer electrolyte solution was mixed in the solvent, and dispersion treatment was performed on the solvent using a planetary ball mill. At this time, the dispersion time was set to 30 minutes, and the catalyst ink was adjusted. The composition ratio of the starting material in the adjusted catalyst ink was set as follows. That is, the mass ratio was set to 1: 1.5: 0.7 in the carbon carrier: oxide-based catalyst substance: polymer electrolyte. As the solvent for the catalyst ink, a solvent obtained by mixing ultrapure water and 1-propanol was used. In the solvent, the volume ratio of ultrapure water to 1-propanol was set to 1: 1. Further, the catalyst ink was adjusted so that the solid content in the catalyst ink was 12% by mass.

〔Base material〕
A polytetrafluoroethylene (PTFE) sheet was used as a base material constituting the transfer sheet.

[Method of forming an electrode catalyst layer on a substrate]
The catalyst ink prepared above was applied onto the substrate by the doctor blade method and dried at 80 ° C. in the air atmosphere. The amount of catalyst ink applied should be such that the electrode catalyst layer forming the fuel electrode (anode) has a platinum loading of 0.05 mg / cm ² , and the electrode catalyst layer forming the air electrode (cathode) has platinum loading. Each was adjusted so that the amount was 0.1 mg / cm ^2.

[Preparation of membrane electrode assembly]
The base material on which the electrode catalyst layer for the anode was formed and the base material on which the electrode catalyst layer for the cathode was formed were punched into a square shape of 5 cm × 5 cm and transferred to both sides of the polymer electrolyte membrane. That is, on the pair of facing surfaces of the polymer electrolyte membrane, the electrode catalyst layer for the anode was transferred to the first surface, and the electrode catalyst layer for the cathode was transferred to the second surface. In this case, setting the transfer temperature to 130 ° C., was set transfer pressure to 5.0 × ¹⁰ 6 Pa. As a result, the membrane electrode assembly of Example 1 was produced.

<Comparative example 1>
[Adjustment of catalyst ink]
A platinum-supported carbon catalyst (catalyst-supported particles) having a loading density of 50% by mass and a polymer electrolyte solution of 25% by mass were mixed in a solvent, and dispersion treatment was performed on the solvent using a planetary ball mill. At this time, the dispersion time was set to 30 minutes, and the catalyst ink was adjusted. The composition ratio of the starting material in the adjusted catalyst ink was set as follows. That is, the mass ratio was set to 1: 0.7 in the carbon carrier: polymer electrolyte. As the solvent for the catalyst ink, a solvent obtained by mixing ultrapure water and 1-propanol was used. In the solvent, the volume ratio of ultrapure water to 1-propanol was set to 1: 1. Further, the catalyst ink was adjusted so that the solid content in the catalyst ink was 12% by mass.

〔Base material〕
A polytetrafluoroethylene (PTFE) sheet was used as a base material constituting the transfer sheet.

[Method of forming an electrode catalyst layer on a substrate]
The catalyst ink prepared above was applied onto the substrate by the doctor blade method and dried at 80 ° C. in the air atmosphere. The amount of catalyst ink applied should be such that the electrode catalyst layer forming the fuel electrode (anode) has a platinum loading of 0.05 mg / cm ² , and the electrode catalyst layer forming the air electrode (cathode) has platinum loading. Each was adjusted so that the amount was 0.1 mg / cm ^2.

[Preparation of membrane electrode assembly]
The base material on which the electrode catalyst layer for the anode was formed and the base material on which the electrode catalyst layer for the cathode was formed were punched into a square shape of 5 cm × 5 cm and transferred to both sides of the polymer electrolyte membrane. That is, on the pair of facing surfaces of the polymer electrolyte membrane, the electrode catalyst layer for the anode was transferred to the first surface, and the electrode catalyst layer for the cathode was transferred to the second surface. In this case, setting the transfer temperature to 130 ° C., was set transfer pressure to 5.0 × ¹⁰ 6 Pa. As a result, the membrane electrode assembly of Comparative Example 1 was produced.

<Comparative example 2>
[Adjustment of catalyst ink]
A platinum-supported carbon catalyst (catalyst-supported particles) having a loading density of 50% by mass, a particulate oxide-based catalyst substance (TiONP) having an average particle size of 0.1 μm, and a polymer electrolyte solution of 25% by mass. Was mixed in a solvent, and dispersion treatment was performed on the solvent using a planetary ball mill. At this time, the dispersion time was set to 30 minutes, and the catalyst ink was adjusted. The composition ratio of the starting material in the adjusted catalyst ink was set as follows. That is, the mass ratio was set to 1: 1.5: 0.7 in the carbon carrier: oxide-based catalyst substance: polymer electrolyte. As the solvent for the catalyst ink, a solvent obtained by mixing ultrapure water and 1-propanol was used. In the solvent, the volume ratio of ultrapure water to 1-propanol was set to 1: 1. Further, the catalyst ink was adjusted so that the solid content in the catalyst ink was 12% by mass.

〔Base material〕
A polytetrafluoroethylene (PTFE) sheet was used as a base material constituting the transfer sheet.

[Method of forming an electrode catalyst layer on a substrate]
The catalyst ink prepared above was applied onto the substrate by the doctor blade method and dried at 80 ° C. in the air atmosphere. The amount of the catalyst ink applied should be such that the electrode catalyst layer forming the fuel electrode (anode) has a platinum loading of 0.05 mg / cm ² , and the electrode catalyst layer forming the air electrode (anode) has platinum loading. The amount was adjusted to 0.1 mg / cm ^2.

[Preparation of membrane electrode assembly]
The base material on which the electrode catalyst layer for the anode was formed and the base material on which the electrode catalyst layer for the cathode was formed were punched into a square shape of 5 cm × 5 cm and transferred to both sides of the polymer electrolyte membrane. In this case, setting the transfer temperature to 130 ° C., was set transfer pressure to 5.0 × ¹⁰ 6 Pa. As a result, the membrane electrode assembly of Comparative Example 2 was produced.

<Evaluation>
[Power generation characteristics]
A sample was prepared by laminating carbon paper as a gas diffusion layer so as to sandwich each of the membrane electrode assemblies of Example 1 and Comparative Examples 1 and 2. Then, each sample was installed in the power generation evaluation cell, and the current and voltage were measured using the fuel cell measuring device. The cell temperature at the time of measurement was set to 65 ° C., and the operating conditions were set to high humidification and low humidification as shown below. Further, hydrogen was used as the fuel gas and air was used as the oxidant gas. At this time, the hydrogen flow rate was set to a flow rate at which the hydrogen utilization rate was 90%, and the air flow rate was set to a flow rate at which the oxygen utilization rate was 40%. The back pressure was set to 50 kPa.

[Operating conditions]
Condition 1 (high humidification): Relative humidity Anode: 90% RH, Cathode: 80% RH
Condition 2 (low humidification): Relative humidity Anode: 90% RH, Cathode: 30% RH

〔Measurement result〕
The polymer electrolyte fuel cell provided with the membrane electrode assembly of Example 1 is superior to the polymer electrolyte fuel cell provided with the membrane electrode assembly of Comparative Examples 1 and 2 under high humidification operating conditions. showed that. Further, it was found that the membrane electrode assembly of Example 1 had the same power generation performance as the low humidification operating condition even under the high humidification operating condition. In particular, according to the membrane electrode assembly of Example 1, the power generation performance was improved ^{when the current density was around 1.5 A / cm 2.}

Under high humidification operating conditions, in the solid polymer fuel cell provided with the membrane electrode assembly of Example 1 ^{, the cell voltage at a current density of 1.5 A / cm 2} was found in the membrane electrode assembly of Comparative Example 1. It was found to be 0.28 V higher than the cell voltage at a current density of 1.5 A / cm ^2. Further, under highly humidified operating conditions, in the polymer electrolyte fuel electron provided with the membrane electrode assembly of Example 1 ^{, the cell voltage at a current density of 1.5 A / cm 2} is the membrane electrode assembly of Comparative Example 2. It was found to be 0.24 V higher than the cell voltage at a current density ^{of 1.5 A / cm 2} in the polymer electrolyte fuel cell equipped with the body.

From the measurement results of the power generation performance of the polymer electrolyte fuel cell including the membrane electrode assembly of Example 1 and the power generation characteristics of the polymer electrolyte fuel cell including the membrane electrode assembly of Comparative Examples 1 and 2, Examples According to the membrane electrode assembly of No. 1, it was confirmed that the drainage property was enhanced, and thus the power generation characteristics under the operating conditions of high humidification showed the same power generation characteristics as those under the operating conditions of low humidification.

Further, under low humidification operating conditions, in the polymer electrolyte fuel cell provided with the membrane electrode assembly of Example 1 ^{, the cell voltage at a current density of 1.5 A / cm 2} is the membrane electrode assembly of Comparative Example 1. It was found to be 0.31 V higher than the cell voltage at a current density ^{of 1.5 A / cm 2} in the polymer electrolyte fuel cell equipped with the body. Further, under the operating conditions of low humidification, in the polymer electrolyte fuel cell provided with the membrane electrode assembly of Example 1 ^{, the cell voltage at a current density of 1.5 A / cm 2} is the membrane electrode assembly of Comparative Example 2. It was found to be 0.27 V higher than the cell voltage at a current density ^{of 1.5 A / cm 2} in the polymer electrolyte fuel cell equipped with the body.

From the measurement results of the power generation performance of the polymer electrolyte fuel cell including the membrane electrode assembly of Example 1 and the power generation characteristics of the polymer electrolyte fuel cell including the membrane electrode assembly of Comparative Examples 1 and 2, Examples According to the membrane electrode assembly of No. 1, it was confirmed that the drainage property of the water generated by the electrode reaction was high and the water retention under the operating conditions of low humidification was not hindered.

1 ... Polymer electrolyte membrane 2 ... Electrode catalyst layer 3 ... Electrode catalyst layer 4 ... Gas diffusion layer 5 ... Gas diffusion layer 6 ... Air electrode (cathode)
7 ... Fuel electrode (anode)
8a, 8b ... Gas flow path 9a, 9b ... Cooling water flow path 10a, 10b ... Separator 11 ... Membrane electrode assembly 12 ... Solid polymer fuel cell

Claims (9)

A polymer electrolyte membrane and a pair of electrode catalyst layers that sandwich the polymer electrolyte membrane are provided.
At least one of the pair of electrode catalyst layers contains particles carrying a catalyst composed of a noble metal component, a polymer electrolyte, and a fibrous oxide-based catalyst substance.
The fibrous oxide catalyst substance is a membrane electrode assembly for a fuel cell containing at least one transition metal element selected from the group composed of Ta, Nb, Ti, and Zr. The fuel cell according to claim 1, wherein the electrode catalyst layer containing the particles, the polymer electrolyte, and the fibrous oxide meter catalyst material includes an electrode catalyst layer for a positive electrode in a polymer electrolyte fuel cell. Membrane electrode assembly. The fuel cell according to claim 1 or 2, wherein the fibrous oxide-based catalyst substance is a substance in which the nitride of the transition metal element contains P as a substitution atom and the nitride is partially oxidized. Membrane electrode assembly. The membrane electrode assembly for a fuel cell according to any one of claims 1 to 3, wherein the transition metal element is Ti. Any one of claims 1 to 4, wherein the average fiber diameter of the oxide-based catalyst substance is contained in the range of 20 nm or more and 1 μm or less, and the average fiber length is contained in the range of 1.2 μm or more and 30 μm or less. The membrane electrode assembly for a fuel cell according to the section. The ratio (MB / MA) of the mass (MB) of the oxide-based catalyst substance to the mass (MA) of the carrier in the catalyst-supporting particles composed of the noble metal component is contained in the range of 0.1 times or more and 10 times or less. The membrane electrode assembly for a fuel cell according to any one of claims 1 to 5. The ratio (MC / MA) of the mass (MC) of the polymer electrolyte to the mass (MA) of the carrier in the catalyst-supporting particles composed of the noble metal component is included in the range of 0.1 times or more and 1.4 or less. The membrane electrode assembly for a fuel cell according to any one of claims 1 to 6. The membrane electrode assembly for a fuel cell according to any one of claims 1 to 7, wherein the particles carrying the catalyst composed of the noble metal component are covered with a hydrophobic film. The membrane electrode assembly for a fuel cell according to any one of claims 1 to 8.
A pair of gas diffusion layers that sandwich the membrane electrode assembly for a fuel cell,
A polymer electrolyte fuel cell comprising a pair of separators sandwiching the pair of gas diffusion layers.