JP5487701B2 - Membrane electrode assembly, method for producing the same, and polymer electrolyte fuel cell - Google Patents

Description

  The present invention relates to a membrane electrode assembly, a manufacturing method thereof, and a polymer electrolyte fuel cell, and more particularly to a membrane electrode assembly used in a polymer electrolyte fuel cell, a manufacturing method thereof, and a polymer electrolyte fuel cell.

  A fuel cell is a power generation system that generates electricity by using hydrogen and oxygen as fuel and causing reverse reaction of water electrolysis. This has features such as high efficiency, low environmental load and low noise compared with the conventional power generation method, and is attracting attention as a clean energy source in the future. Fuel cells can be classified according to the electrolyte used in the fuel cell. The types of fuel cells include molten carbonate fuel cells, phosphoric acid fuel cells, solid oxide fuel cells, solid polymer fuel cells, and the like.

  Among the fuel cells, the polymer electrolyte fuel cell can be operated in a low temperature region, and is generally used at an operating temperature of 80 ° C. to 100 ° C., such as an in-vehicle power source or a household stationary power source. Promising use. BACKGROUND ART A polymer electrolyte fuel cell includes a joined body in which a pair of electrode catalyst layers are arranged on both surfaces of a polymer electrolyte membrane called a membrane electrode assembly (hereinafter sometimes referred to as “MEA”). The battery is sandwiched between a pair of separator plates in which a gas flow path for supplying a fuel gas containing hydrogen to one electrode catalyst layer and an oxidant gas containing oxygen to the other electrode catalyst layer is formed. . Here, the electrode for supplying the fuel gas is called a fuel electrode, and the electrode for supplying the oxidant gas is called an air electrode.

  Each of the fuel electrode and the air electrode is provided with a catalyst material. As the catalyst material, a material in which a catalytically active material such as metal catalyst particles such as platinum or platinum alloy is supported on a conductive material such as carbon particles is generally used. Since a metal catalyst such as platinum used as a catalyst material is a very expensive material, a reduction in the amount of platinum used is desired in the practical application of fuel cells.

  In addition, as an alternative material for an expensive platinum catalyst, it has been reported that group 4 and 5 transition metal oxides containing nitrogen, carbon and the like have excellent stability and oxygen reduction catalytic ability.

  Conventionally, various attempts have been made to improve the output performance of fuel cells. For example, Patent Document 1 discloses a fuel cell in which the side of the electrode catalyst layer having a larger amount of polymer electrolysis is joined to the polymer electrolyte membrane to increase proton conductivity at the interface between the electrode catalyst layer and the polymer electrolyte membrane. Has been. In Patent Document 2, the electrode catalyst layer contains a massive polymer electrolyte, so that the massive polymer electrolyte functions as a large proton conduction path. Therefore, high proton conductivity is exhibited even under high temperature and low humidification conditions. Moreover, since the ionic conductivity in the catalyst layer is increased, an IR loss is reduced, and a fuel cell capable of obtaining high output characteristics is disclosed.

Japanese Patent Laid-Open No. 11-126615 JP 2005-85611 A

  The present invention comprises a composite catalyst particle having a polymer electrolyte, a catalyst material, and an electron conductive material, and a polymer electrolyte particle in the electrode catalyst layer, and has gas diffusibility to the surface of the catalyst material and proton conductivity in the electrode catalyst layer. The present invention also provides a membrane electrode assembly, a method for producing the same, and a polymer electrolyte fuel cell.

  As a result of intensive studies, the present inventor has been able to solve the above-mentioned problems and has completed the present invention.

The invention according to claim 1 of the present invention includes a solid polymer electrolyte membrane, a composite catalyst particle having a pair of polymer electrolytes formed on both sides of the solid polymer electrolyte membrane, a catalyst material and an electron conductive material, and a polymer. comprising an electrode catalyst layer made of the electrolyte particles, an average particle diameter of the composite catalyst particles is at 1μm or more 10μm or less, an average particle diameter of the polymer electrolyte particles are characterized der Rukoto least 1μm below 100nm This is a membrane electrode assembly.

The invention according to claim 2 of the present invention is characterized in that the catalyst particle size of the catalyst material is 0.5 nm or more and 20 nm or less, and the particle size of the electron conductive material is 10 nm or more and 1 μm or less. The membrane electrode assembly described is used.

The invention according to claim 3 of the present invention is the membrane electrode assembly according to claim 1 or 2, wherein the polymer electrolyte is the same material as the solid polymer electrolyte membrane.

According to a fourth aspect of the present invention, the membrane electrode assembly according to any one of the first to third aspects is sandwiched between a pair of gas diffusion layers, and the pair of gas diffusion layers is a pair of separators. The polymer electrolyte fuel cell is characterized by being sandwiched.

In the invention according to claim 5 of the present invention, a solid polymer electrolyte membrane is formed, a polymer electrolyte, a catalyst material, an electron conductive material, and a solvent are mixed to produce a catalyst ink, and the polymer electrolyte is dispersed. A polymer electrolyte solution is prepared, the catalyst ink is spray-dried, the composite catalyst particles are granulated, the polymer electrolyte solution is spray-dried to granulate the polymer electrolyte particles, and the composite catalyst particles are 1 μm or more Classifying to an average particle size of 10 μm or less , classifying the polymer electrolyte particles to an average particle size of 100 nm or more and 1 μm or less, mixing composite catalyst particles and polymer electrolyte particles, and forming a pair on both sides of the solid polymer electrolyte membrane The electrode catalyst layer is formed as a method for producing a membrane electrode assembly.

In the invention according to claim 6 of the present invention, the catalyst substance mixed with the catalyst ink has a catalyst particle diameter of 0.5 nm to 20 nm, and the electron conductive substance particle diameter of 10 nm to 1 μm. The method for producing a membrane electrode assembly according to claim 5, wherein:

The invention according to claim 7 of the present invention is the membrane electrode according to claim 5 or 6, wherein the polymer electrolyte mixed with the catalyst ink is the same material as the solid polymer electrolyte membrane. This is a method for manufacturing a joined body.

The invention according to claim 8 of the present invention is a membrane electrode assembly manufactured by the method for manufacturing a membrane electrode assembly according to any one of claims 5 to 7 .

The invention according to claim 9 of the present invention is characterized in that the membrane electrode assembly according to claim 8 is sandwiched between a pair of gas diffusion layers, and further, the pair of gas diffusion layers is sandwiched between a pair of separators. This is a method for producing a polymer electrolyte fuel cell.

  According to the present invention, the electrode catalyst layer comprises a composite catalyst particle having a polymer electrolyte, a catalyst material, and an electron conductive material, and a polymer electrolyte particle. The gas diffusivity to the surface of the catalyst material and the protons in the electrode catalyst layer are It is possible to provide a membrane electrode assembly having both conductivity, a method for producing the same, and a polymer electrolyte fuel cell.

It is a schematic sectional drawing which shows the membrane electrode assembly which concerns on embodiment of this invention. It is a schematic sectional drawing which shows the membrane electrode assembly which concerns on embodiment of this invention. 1 is a schematic exploded view showing a polymer electrolyte fuel cell according to an embodiment of the present invention.

  Below, the membrane electrode assembly (MEA) and fuel cell which concern on embodiment of this invention are demonstrated. The embodiments of the present invention are not limited to the embodiments described below, and modifications such as design changes can be added based on the knowledge of those skilled in the art. Embodiments to which is added can also be included in the scope of the embodiments of the present invention.

  FIG. 1 is a schematic cross-sectional view showing a membrane electrode assembly (MEA) 12 according to an embodiment of the present invention. As shown in FIG. 1, a membrane electrode assembly (MEA) 12 according to an embodiment of the present invention includes a solid polymer electrolyte membrane 1 and an electrode catalyst layer (air electrode) on one surface of the solid polymer electrolyte membrane 1. Side) 2 and an electrode catalyst layer (fuel electrode side) 3 on the other surface of the solid polymer electrolyte membrane 1.

  Next, the electrode catalyst layer 2 (air electrode side) and the electrode catalyst layer (fuel electrode side) 3 will be described with reference to FIG. FIG. 2 is a schematic sectional view showing a membrane electrode assembly (MEA) 12 according to the embodiment of the present invention. As shown in FIG. 2, the membrane electrode assembly (MEA) 12 according to the embodiment of the present invention includes a polymer electrolyte and an electrode catalyst layer (air electrode side) 2 and an electrode catalyst layer (fuel electrode side) 3. Composite catalyst particles 2a and 3a having a catalyst material and an electron conductive material and polymer electrolyte particles 2b and 3b are mixed and formed. The polymer electrolyte particles 2b and 3b can enhance proton conductivity in the electrode catalyst layers 2 and 3 and at the interface between the electrode catalyst layers 2 and 3 and the solid polymer electrolyte membrane 1. Moreover, the content rate of the polymer electrolyte of the composite catalyst particles 2a and 3a can be reduced, and the gas supply to the catalyst substance surface can be ensured. Furthermore, by using the composite catalyst particles 2a and 3a and the polymer electrolyte particles 2b and 3b whose average particle diameter is controlled, the gas diffusibility in the electrode catalyst layers 2 and 3 can be sufficiently secured. Further, an air electrode side gas diffusion layer 4 is provided on the electrode catalyst layer 2, and a fuel electrode side gas diffusion layer 5 is provided on the electrode catalyst layer 3.

  As the catalyst material and the electron conductive material in the composite catalyst particles 2a and 3a of the electrode catalyst layers 2 and 3 according to the embodiment of the present invention, carbon black carrying platinum is preferably used. There is no problem even if a group 4 or 5 transition metal oxide containing nitrogen, carbon or the like is used as an alternative material for the catalyst.

  The average particle diameter of the composite catalyst particles 2a and 3a of the electrode catalyst layers 2 and 3 according to the embodiment of the present invention is preferably 0.5 μm or more and 20 μm or less, and more preferably 1 μm or more and 10 μm or less. If the average particle size is less than 0.5 μm, sufficient pores cannot be secured between the composite catalyst particles 2a and 3a, resulting in flooding. On the other hand, if the average particle diameter exceeds 20 μm, the catalyst inside the composite catalyst particles 2a and 3a cannot be used effectively, and the catalyst utilization rate decreases. On the other hand, when the average particle diameter of the composite catalyst particles 2a and 3a is 1 μm or more and 10 μm or less, both the gas diffusibility to the catalyst material surface and the proton conductivity in the electrode catalyst layers 2 and 3 can be provided.

  In addition, a method has been proposed in which the particle size of carbon black, which is an electron conductive material, is increased on the gas diffusion layer side and decreased on the solid polymer electrolyte membrane side. The (pores) are as small as several tens of nm, the gas diffusibility is not sufficient, and the generated water is difficult to discharge. On the other hand, in the embodiment of the present invention, the pores (pores) formed in the electrode catalyst layers 2 and 3 are particles in addition to the conventional ones of about several tens of nm derived from carbon black. Including large ones of 0.1 μm to 5 μm level derived from the interstices, sufficient gas diffusibility can be ensured and smooth generated water can be discharged.

  The average particle diameter of the polymer electrolyte particles 2b and 3b of the electrode catalyst layers 2 and 3 according to the embodiment of the present invention is preferably 100 nm or more and 1 μm or less. If the average particle diameter is less than 100 nm, the pores in the electrode catalyst layers 2 and 3 are blocked, and gas diffusibility cannot be ensured. On the other hand, when the average particle diameter exceeds 1 μm, the surface area becomes small and the efficiency of the electrode reaction decreases.

  Next, the polymer electrolyte fuel cell 13 using the membrane electrode assembly 12 according to the embodiment of the present invention will be described. FIG. 3 is a schematic exploded view showing the polymer electrolyte fuel cell 13 according to the embodiment of the present invention. As shown in FIG. 3, a polymer electrolyte fuel cell 13 according to an embodiment of the present invention includes a membrane electrode assembly 12 having an electrode catalyst layer 2 and an electrode catalyst layer 3 on both sides of a solid polymer electrolyte membrane 1. The air electrode side gas diffusion layer 4 and the fuel electrode side gas diffusion layer 5 are disposed so as to face the electrode catalyst layer 2 and the electrode catalyst layer 3. Thereby, the air electrode 6 and the fuel electrode 7 are comprised, respectively. Then, a set of separators 10 made of a conductive and impermeable material, which is provided with a gas flow path 8 for gas flow and is provided with a cooling water flow path 9 for cooling water flow on the opposing main surface, is disposed. For example, hydrogen gas is supplied as a fuel gas from the gas flow path 8 of the separator 10 on the fuel electrode 7 side. On the other hand, a gas containing oxygen, for example, is supplied as an oxidant gas from the gas flow path 8 of the separator 10 on the air electrode 6 side.

As shown in FIG. 3, a polymer electrolyte fuel cell 13 according to an embodiment of the present invention includes a set of separators 10 and a polymer electrolyte membrane 1, an electrode catalyst layer 2, an electrode catalyst layer 3, and a gas diffusion layer. 4 and is a gas diffusion layer 5 which is a solid polymer electrolyte fuel cell 13 of the so-called single cell structure for clamping, in the embodiment of the present invention, by laminating a plurality of cells in series via the separators 10 stacked It can also be a stack structure.

  Next, the manufacturing method of the membrane electrode assembly (MEA) 12 and the manufacturing method of the polymer electrolyte fuel cell 13 according to the embodiment of the present invention will be described.

  First, as shown in FIG. 1, a solid polymer electrolyte membrane 1 of a membrane electrode assembly (MEA) 12 according to an embodiment of the present invention is prepared. The solid polymer electrolyte membrane 1 is not particularly limited as long as it is made of a material that is excellent in proton conductivity and does not flow electrons. In particular, perfluoro-type sulfonic acid membranes such as Nafion (registered trademark) manufactured by DuPont, Flemion (registered trademark) manufactured by Asahi Glass Co., Ltd., Aciplex (registered trademark) manufactured by Asahi Glass Co., Ltd. and Gore Select (registered trademark) manufactured by Japan Gore-Tex Etc. can be used. In addition, a hydrocarbon resin such as polyimide having a proton conductive group can also be used.

  The polymer electrolyte membrane 1 of the membrane electrode assembly (MEA) 12 according to the embodiment of the present invention is preferably made of the same material as the polymer electrolyte used for the electrode catalyst layer 2 and the electrode catalyst layer 3.

  Next, the electrode catalyst layer 2 and the electrode catalyst layer 3 are formed on both surfaces of the prepared solid polymer electrolyte membrane 1. In forming the electrode catalyst layer 2 and the electrode catalyst layer 3, a catalyst ink containing a polymer electrolyte, a catalyst material, a carbon carrier carrying the catalyst material, and a dispersion medium is prepared.

  Various polymer electrolytes are used in the catalyst ink, but the same material as the solid polymer electrolyte membrane 1 can be used, and the same material as the solid polymer electrolyte membrane 1 is preferably used. . When Nafion (registered trademark) manufactured by DuPont is used as the solid polymer electrolyte membrane 1, it is preferable to use Nafion as the polymer electrolyte contained in the catalyst ink. When a material other than Nafion is used for the solid polymer electrolyte membrane 1, it is preferable to optimize such as dissolving the same components as the solid polymer electrolyte membrane 1 in the catalyst ink.

  As the catalyst material of the membrane electrode assembly (MEA) 12 according to the embodiment of the present invention, those generally used can be used, and are not particularly limited. Specifically, for example, as platinum of platinum-supported carbon, carbon particles or the like on which platinum alone or a platinum alloy is supported can be used. Examples of the alloy include palladium, ruthenium, and molybdenum, and ruthenium is particularly desirable. Moreover, tungsten, tin, rhenium, etc. may be contained as an additive in the platinum alloy. When the additive is contained, the CO poisoning resistance can be increased. The additive metal may exist as an intermetallic compound of a platinum alloy or may form an alloy. The catalyst particle size is preferably 0.5 nm or more and 20 nm or less. More preferably, it is 1 nm or more and 5 nm or less. If the catalyst particle diameter exceeds 20 nm, the activity of the catalyst decreases, and if it is less than 0.5 nm, the stability of the catalyst decreases.

  The catalyst material described above is supported on a carbon support. The type of the carbon carrier may be any fine particle that is electrically conductive and is not affected by the catalyst. Graphite carbon, carbon fiber, carbon nanotube, nanohorn, and fullerene are preferably used. Can do. The particle size of the carbon support is preferably about 10 nm to 1 μm. More preferably, it is 10 nm or more and 100 nm or less. When the particle size of the carbon support is less than 10 nm, it becomes difficult to form an electron conduction path. When the particle size exceeds 1 μm, the gas diffusibility of the electrode catalyst layer 2 and the electrode catalyst layer 3 decreases, and the utilization rate of the catalyst decreases. End up.

  The solvent used as the dispersion medium for the catalyst ink is not particularly limited as long as it does not erode the catalyst particles or the hydrogen ion conductive resin, and can dissolve or disperse the proton conductive polymer in a highly fluid state as a fine gel. Although there is no restriction | limiting, it is desirable that at least the emissive liquid organic solvent is included, and it is not specifically limited. Examples of the solvent used as a dispersion medium for the catalyst ink include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutyl alcohol, tert-butyl alcohol, pentanol, 2-heptanol, Alcohols such as benzyl alcohol, acetone, methyl ethyl ketone, methyl propyl ketone, methyl butyl ketone, methyl isobutyl ketone, methyl amyl ketone, pentanone, heptanone, cyclohexanone, methyl cyclohexanone, acetonyl acetone, diethyl ketone, dipropyl ketone, diisobutyl Ketones such as ketones, tetrahydrofuran, tetrahydropyran, dioxane, diethylene glycol dimethyl ether, anisole, methoxytoluene, diethyl ether , Ethers such as dipropyl ether and dibutyl ether, amines such as isopropylamine, butylamine, isobutylamine, cyclohexylamine, diethylamine and aniline, propyl formate, isobutyl formate, amyl formate, methyl acetate, ethyl acetate, propyl acetate, acetic acid Esters such as butyl, isobutyl acetate, pentyl acetate, isopentyl acetate, methyl propionate, ethyl propionate, butyl propionate, other acetic acid, propionic acid, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, ethylene glycol, diethylene glycol, propylene Glycol, ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diacetone alcohol Lumpur, polar solvents such as 1-methoxy-2-propanol is used. Moreover, what mixed 2 or more types of these solvents can also be used.

  By using two types of solvents having different dielectric constants among these solvents, the dispersion state of the polymer electrolyte in the catalyst ink can be controlled. These solvents or those using lower alcohols as the solvent have a high risk of ignition, and when using such a solvent, it is preferable to use a mixed solvent with water. Further, water that is compatible with the polymer electrolyte may be contained. The amount of water added is not particularly limited as long as the proton conductive polymer is not separated to cause white turbidity or gelation.

  Further, the catalyst ink may contain a dispersant in order to disperse the carbon carrier carrying the catalyst substance. As the dispersant, an anionic surfactant, a cationic surfactant, an amphoteric surfactant, a nonionic surfactant, or the like can be used.

  The catalyst ink may contain a pore forming agent. By removing the pore-forming agent after the electrode catalyst layers 2 and 3 are formed, pores can be formed. Examples include substances that are soluble in acids, alkalis, and water, substances that sublime such as camphor, and substances that thermally decompose. If the substance is soluble in hot water, it may be removed with water generated during power generation.

  Examples of pore-forming agents that are soluble in acids, alkalis, and water include, for example, acid-soluble inorganic salts such as calcium carbonate, barium carbonate, magnesium carbonate, magnesium sulfate, and magnesium oxide, and inorganic salts that are soluble in an alkaline aqueous solution such as alumina, silica gel, and silica sol. , Metals soluble in acids or alkalis such as aluminum, zinc, tin, nickel and iron, water-soluble inorganic salts such as sodium chloride, potassium chloride, ammonium chloride, sodium carbonate, sodium sulfate and monosodium phosphate, polyvinyl alcohol, Examples include water-soluble organic compounds such as polyethylene glycol, and it is also effective to use two or more kinds in combination.

  The viscosity of the catalyst ink is preferably from 0.1 cP to 100 cP. If the viscosity of the catalyst ink exceeds 100 cP, it becomes difficult to spray the ink in the spray-drying liquid feed line and in the spray nozzle portion. On the other hand, when the viscosity of the catalyst ink is less than 0.1 cP, the granulation rate is very slow and the productivity is lowered. The viscosity is optimized by changing the type of solvent and the solid content concentration. Further, the viscosity can be controlled by adding a dispersing agent when the ink is dispersed.

  The catalyst ink containing the polymer electrolyte, the catalyst material, the carbon carrier carrying the catalyst material, and the dispersion medium is appropriately dispersed by a known method.

  Composite catalyst particles are granulated by spray drying the above catalyst ink by spray drying. The spray drying temperature needs to be optimized in accordance with the boiling point of the solvent in the catalyst ink used and the glass transition temperature of the polymer electrolyte. In particular, when the spray drying temperature is higher than the glass transition temperature, not only composite catalyst particles having a uniform particle diameter can be obtained, but also proton conductivity in the polymer electrolyte may be lowered.

  In the spray drying method, composite catalyst particles having a desired particle diameter can be granulated by changing the viscosity of the catalyst ink, the temperature during spray drying, the amount of spray liquid, the spray pressure, and the like.

  The granulated composite catalyst particles 2a and 3a are applied onto the solid polymer electrolyte membrane 1 or the gas diffusion layers 4 and 5 by a dry coating method such as an electrostatic screen method. And the electrode catalyst layer 3 is formed. Also, using a transfer substrate, the composite catalyst particles 2a and 3a are coated on the transfer substrate, and the electrode catalyst layer 2 and the electrode catalyst layer 3 are once formed on the transfer substrate. The electrode catalyst layer 2 and the electrode catalyst layer 3 may be formed on the membrane 1.

  The electrode catalyst layer 2, the electrode catalyst layer 3, and the solid polymer electrolyte membrane 1 are joined by thermocompression bonding. Further, a solution containing a proton conductive polymer can be applied as a binder between the electrode catalyst layer 2, the electrode catalyst layer 3 and the proton conductive polymer in order to improve the bonding property.

  Further, as the gas diffusion layer 4, the gas diffusion layer 5 and the separator 10 of the polymer electrolyte fuel cell 13 according to the embodiment of the present invention, those used in ordinary fuel cells can be used. Specifically, porous carbon materials such as carbon cloth, carbon paper, and nonwoven fabric are used for the gas diffusion layer 4 and the gas diffusion layer 5. As the separator 10, a carbon type metal type or the like can be used. The fuel cell is manufactured by assembling other accompanying devices such as a gas supply device and a cooling device.

  In the polymer electrolyte fuel cell 13 according to the embodiment of the present invention, in the electrode catalyst layers 2 and 3 of the membrane electrode assembly 12, composite catalyst particles and polymer having a polymer electrolyte, a catalyst material, and an electron conductive material are used. It consists of electrolyte particles, and can have both gas diffusibility to the surface of the catalyst material and proton conductivity in the electrode catalyst layers 2 and 3, and good power generation characteristics can be obtained.

  The present invention will be described below with reference to examples. In addition, this invention is not limited to an Example.

[Preparation of catalyst ink]
Using Ketjen Black carrying 50 wt% platinum as a catalyst material, pure water and a solution of Nafion (registered trademark) manufactured by DuPont were dispersed using a planetary ball mill of Pulversette 7 manufactured by Fritsch. A catalyst ink was obtained using a ball mill pot and balls made of zirconia. At this time, the electrolyte weight (N) in the Nafion solution was adjusted to 0.3 with respect to the weight (C) 1 of ketjen black.

[Granulation of composite catalyst particles and polymer electrolyte particles]
Using the prepared catalyst ink, the catalyst ink was granulated by a spray dryer method to produce composite catalyst particles. The spraying temperature was 80 ° C., and N ₂ was used as the liquid feeding gas. The obtained composite catalyst particles were classified. When the obtained composite catalyst particle diameter was observed with a scanning electron microscope, the average particle diameter was 4 μm. Moreover, the polymer electrolyte particle was produced by spray-drying the dispersion solution of a polymer electrolyte.

[Method for producing transfer sheet having electrode catalyst layer]
On the transfer substrate, composite catalyst particles and polymer electrolyte particles were mixed and applied to form an electrode catalyst layer. At this time, the electrode catalyst layer was formed so that the Pt (platinum) mass of the electrode catalyst layer per unit area was 0.3 mg / cm ² . After the formation, it was punched into a predetermined electrode size to obtain a transfer sheet.

[Preparation of membrane electrode assembly 12]
As the solid polymer electrolyte membrane 1, a proton conductive polymer membrane, Nafion (registered trademark) 212 manufactured by DuPont was used. The solid polymer electrolyte membrane 1 is sandwiched on both sides of a prepared transfer base material by a transfer sheet having an electrode catalyst layer, and thermocompression bonded under conditions of 130 ° C. and 6.0 MPa, and only the transfer base material is peeled off. A membrane electrode assembly 12 was obtained.

  Carbon paper was disposed as a gas diffusion layer on both surfaces of the membrane electrode assembly 12 thus obtained, and was further sandwiched between a pair of calcined carbon separators 10 to produce a single-cell solid polymer fuel cell 13.

[Comparative example]
Using the same catalyst ink as in the example, the catalyst ink was applied onto the transfer substrate, and then the solvent was dried to form an electrode catalyst layer. At this time, the electrode catalyst layer was formed so that the mass of Pt (platinum) per unit area was 0.3 mg / cm ² . As the solid polymer electrolyte membrane 1, a proton conductive polymer membrane, Nafion 212 manufactured by DuPont was used. The solid polymer electrolyte membrane 1 is sandwiched between transfer electrodes each having an electrode catalyst layer in order on a transfer substrate prepared in advance, and thermocompression bonded under conditions of 130 ° C. and 6.0 MPa. The membrane electrode assembly 12 was obtained. Similarly to the example, carbon paper was disposed as a gas diffusion layer on both surfaces of the obtained membrane electrode assembly 12, and was further sandwiched between a pair of calcined carbon separators 10 to provide a single cell solid polymer fuel. A battery 13 was produced.

[Evaluation of power generation characteristics]
The power generation characteristics were evaluated with a GFT-SG1 fuel cell measuring device manufactured by Toyo Technica. Hydrogen gas was used as the fuel and air was used as the oxidant.

  When the power generation evaluation of the polymer electrolyte fuel cell 13 produced using the membrane electrode assembly 12 of the example and the comparative example was performed, the polymer electrolyte fuel cell 13 of the example did not generate flooding or the like. Good power generation characteristics could be obtained.

  DESCRIPTION OF SYMBOLS 1 ... Solid polymer electrolyte membrane, 2 ... Electrode catalyst layer (air electrode side), 3 ... Electrode catalyst layer (fuel electrode side), 4 ... Air electrode side gas diffusion layer, 5 ... Fuel electrode side gas diffusion layer, 6 ... Air electrode, 7 ... Fuel electrode, 8 ... Gas flow path, 9 ... Cooling water flow path, 10 ... Separator, 12 ... Membrane electrode assembly, 13 ... Solid polymer fuel cell

Claims (9)

A solid polymer electrolyte membrane;
A pair of polymer electrolytes formed on both surfaces of the solid polymer electrolyte membrane, a composite catalyst particle having a catalyst substance and an electron conductive substance, and an electrode catalyst layer comprising the polymer electrolyte particles,
The composite catalyst particles have an average particle size of 1 μm or more and 10 μm or less,
The membrane electrode assembly, wherein the polymer electrolyte particles have an average particle diameter of 100 nm to 1 μm. The catalyst particle diameter of the catalyst material is 0.5 nm or more and 20 nm or less,
2. The membrane electrode assembly according to claim 1, wherein a particle diameter of the electron conductive material is 10 nm or more and 1 μm or less.   The membrane electrode assembly according to claim 1 or 2, wherein the polymer electrolyte is made of the same material as the solid polymer electrolyte membrane.   The membrane electrode assembly according to any one of claims 1 to 3, wherein the membrane electrode assembly is sandwiched between a pair of gas diffusion layers, and the pair of gas diffusion layers is sandwiched between a pair of separators. Molecular fuel cell. Forming a solid polymer electrolyte membrane,
A polymer electrolyte, a catalyst material, an electron conductive material and a solvent are mixed to prepare a catalyst ink, and a polymer electrolyte solution in which the polymer electrolyte is dispersed is prepared.
The catalyst ink is granulated by spray drying the composite catalyst particles, and the polymer electrolyte particles are granulated by spray drying the polymer electrolyte solution,
Classifying the composite catalyst particles into an average particle size of 1 μm or more and 10 μm or less;
Classifying the polymer electrolyte particles to an average particle size of 100 nm to 1 μm;
A method for producing a membrane electrode assembly, comprising mixing the composite catalyst particles and the polymer electrolyte particles to form a pair of electrode catalyst layers on both surfaces of the solid polymer electrolyte membrane. The catalyst particle diameter of the catalyst substance mixed in the catalyst ink is 0.5 nm or more and 20 nm or less,
6. The method for producing a membrane / electrode assembly according to claim 5, wherein a particle diameter of the electron conductive material is 10 nm or more and 1 μm or less.   The method for producing a membrane electrode assembly according to claim 5 or 6, wherein the polymer electrolyte to be mixed with the catalyst ink is the same material as the solid polymer electrolyte membrane.   A membrane / electrode assembly produced by the method for producing a membrane / electrode assembly according to claim 5.   9. A method for producing a polymer electrolyte fuel cell, comprising sandwiching the membrane electrode assembly according to claim 8 with a pair of gas diffusion layers, and further sandwiching the pair of gas diffusion layers with a pair of separators.