JP6036036B2 - Method for producing electrode catalyst layer for fuel cell, method for producing membrane electrode assembly for fuel cell, and method for producing polymer electrolyte fuel cell - Google Patents

Description

  The present invention relates to an electrode catalyst layer for a fuel cell and a method for producing the same, a membrane electrode assembly for a fuel cell, a method for producing the same, and a polymer electrolyte fuel cell, and more particularly, high power generation using a non-platinum catalyst. The present invention relates to a technique for producing a fuel cell electrode catalyst layer exhibiting characteristics.

  A fuel cell is a power generation system that generates electricity simultaneously with heat by causing a hydrogen gas-containing fuel gas and an oxygen-containing oxidant gas to undergo reverse reaction of water electrolysis at an electrode including a catalyst. This power generation system has features such as high efficiency, low environmental load, and low noise as compared with conventional power generation systems, and is attracting attention as a clean energy source in the future. There are several types depending on the type of ion conductor used in the fuel cell, and those using proton conductive polymer membranes are called solid polymer fuel cells.

  Among fuel cells, polymer electrolyte fuel cells can be used near room temperature, so they are considered promising for use in in-vehicle power sources and household stationary power sources. In recent years, various research and development have been conducted. Yes. The polymer electrolyte fuel cell comprises a membrane electrode assembly (Membrane and Electrode Assembly; hereinafter referred to as MEA) having a pair of electrode catalyst layers disposed on both sides of a polymer electrolyte membrane. In this battery, a fuel gas containing hydrogen is supplied to one of the electrodes, and a gas passage for supplying an oxidant gas containing oxygen to the other electrode is sandwiched between a pair of separator plates. Here, the electrode for supplying the fuel gas is called a fuel electrode, and the electrode for supplying the oxidant is called an air electrode. These electrodes generally comprise an electrode catalyst layer formed by laminating carbon particles carrying a catalyst substance such as a platinum-based noble metal and a polymer electrolyte, and a gas diffusion layer having both gas permeability and electronic conductivity.

  Issues for the practical application of polymer electrolyte fuel cells include improvements in power density and durability, but the biggest issue is cost reduction. In current polymer electrolyte fuel cells, expensive platinum is used as an electrode catalyst, and 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 platinum substitute materials (non-platinum catalysts) that exhibit high oxygen reduction catalytic ability in the air electrode is actively performed.

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

Non-patent document 1 describes a partially oxidized tantalum carbonitride, which shows excellent stability and catalytic ability. However, although this oxide-based non-platinum catalyst shows high oxygen reduction catalytic ability as a single catalyst, it is not supported on carbon particles like platinum catalyst, and it is necessary to optimize the preparation method of the electrode catalyst layer There is.
Patent Document 3 describes an MEA using a non-platinum catalyst. The method for producing the electrode catalyst layer is, for example, a conventional technique used in platinum catalysts described in Patent Document 4 and Patent Document 5 and the like. Therefore, there is a problem that it is not suitable for a non-platinum catalyst.

On the other hand, in recent years, development of non-platinum catalysts exhibiting high oxygen reduction catalytic activity has progressed, and there is a strong demand for improvement in durability, similar to solid polymer fuel cells using platinum as an electrode catalyst.
In a polymer electrolyte fuel cell using a platinum catalyst as an electrode catalyst, there is a problem that the cell performance is deteriorated by long-term operation. Depending on the operating conditions of the polymer electrolyte fuel cell, the reduction of oxygen at the oxygen electrode stops by a two-electron reaction, and hydrogen peroxide (H ₂ O ₂ ) is generated. For example, radical decomposition occurs in the presence of metal ions or the like. . The hydrogen peroxide radical is considered to damage the electrolyte membrane and the electrode catalyst, resulting in a decrease in battery performance.

In the polymer electrolyte fuel cell using a non-platinum catalyst as an electrode catalyst, the catalytic activity is lower than that of the platinum catalyst, so depending on the operating conditions, the reduction of oxygen at the oxygen electrode stops with a two-electron reaction, producing hydrogen peroxide. Is done. Since non-platinum catalysts are more susceptible to damage than platinum catalysts depending on conditions, there is a strong demand for improved durability.
Patent Document 6 describes an electrode catalyst layer in which a sparingly soluble tungstate is added to the electrode catalyst layer as a peroxide decomposition catalyst, but there is no idea that hydrogen peroxide is catalytically decomposed in the vicinity of the electrode catalyst. There is a problem that the electrocatalyst is damaged before catalytic cracking.
Patent Document 7 describes an electrode catalyst layer in which a peroxide decomposition catalyst is supported on a carrier. However, there is no idea that the catalytic ability of catalytic decomposition of hydrogen peroxide is higher than that of an electrode catalyst, However, there is a problem that the electrode catalyst is damaged.

JP 2005-44659 A JP 2005-63677 A JP 2008-270176 A Japanese Patent Application Laid-Open No. 64-62489 Japanese Patent Laid-Open No. 5-36418 Japanese Patent Laying-Open No. 2005-063902 JP 2010-257990 A

“Journal of The Electrochemical Society”, Vol. 155, no. 4, p. B400-B406 (2008)

An object of the present invention is to provide a method for producing an electrode catalyst layer for a fuel cell that exhibits high power generation characteristics using an oxide-based non-platinum catalyst as a catalyst material and has high durability. Another object of the present invention is to produce a membrane electrode assembly for a fuel cell having an electrode catalyst layer for a fuel cell that exhibits high power generation characteristics using an oxide-based non-platinum catalyst as a catalyst material. And a method for producing 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, a catalyst material, carbon particles, peroxide decomposition include catalyst and the polymer electrolyte, and specific surface area is small fuel cell electrode catalyst layer than the carbon particles of the catalyst material A first step of producing a first catalyst ink in which the catalyst substance or the carbon particles are dispersed in a solvent together with the peroxide decomposition catalyst and the first polymer electrolyte; A second step of drying one catalyst ink to embed the catalyst substance and the peroxide decomposition catalyst or the carbon particles and the peroxide decomposition catalyst with the first polymer electrolyte; and the second step. After adding carbon particles or a catalyst substance to the first catalyst ink dried in step 1, the catalyst substance, the carbon particles, the peroxide decomposition catalyst, and the first polymer electrolyte are used as a second polymer electrolyte. With solvent A third step of producing a dispersed second catalyst ink; and applying the second catalyst ink onto a substrate selected from a gas diffusion layer, a transfer sheet, and a polymer electrolyte membrane to form the electrode catalyst layer And a fourth step of forming the electrode catalyst layer for a fuel cell.

The invention according to claim 2 of the present invention is such that the weight ratio of the catalyst substance to the first polymer electrolyte is in the range of 1: 0.01 to 1:30 or the carbon particles and the first polymer. The electrode catalyst layer for a fuel cell is characterized in that the first catalyst ink is dried in the second step so that the weight ratio to the electrolyte is in the range of 1: 0.1 to 1:20. It is a manufacturing method.
The invention according to claim 3 of the present invention is a method for producing an electrode catalyst layer for a fuel cell, wherein the first catalyst ink is dried at a temperature of 30 ° C. or more and 140 ° C. or less in the second step. is there.

  In the invention according to claim 4 of the present invention, after adding carbon particles or a catalyst substance to the first catalyst ink dried in the second step and mixing without solvent, the catalyst substance and the carbon particles A method for producing an electrode catalyst layer for a fuel cell, comprising producing a second catalyst ink in which the peroxide decomposition catalyst and the first polymer electrolyte are dispersed together with a second polymer electrolyte in a solvent. It is.

  According to a fifth aspect of the present invention, carbon particles or a catalyst substance is added to the first catalyst ink dried in the second step and mixed without a solvent, and then the first polymer electrolyte is added. After the heat treatment of the catalyst material or carbon particles embedded in and the added carbon particles or catalyst material at a temperature of 50 ° C. or higher and 180 ° C. or lower, the catalyst material, the carbon particles, the peroxide decomposition catalyst, and the A method for producing an electrode catalyst layer for a fuel cell, comprising producing a second catalyst ink in which a first polymer electrolyte is dispersed in a solvent together with a second polymer electrolyte.

In the invention according to claim 6 of the present invention, the catalyst material is an electrode active material for an oxygen reduction electrode used as a positive electrode of a polymer electrolyte fuel cell, and is selected from tantalum, niobium, titanium, and zirconium. A method for producing an electrode catalyst layer for a fuel cell, comprising at least one transition metal element.
According to a seventh aspect of the present invention, there is provided an electrode catalyst layer for a fuel cell, wherein the catalyst material is obtained by partially oxidizing the carbonitride of the transition metal element in an atmosphere containing oxygen. It is a manufacturing method.

The invention according to claim 8 of the present invention is the method for producing an electrode catalyst layer for a fuel cell, wherein the transition metal element is tantalum.
The invention according to claim 9 of the present invention is a method for producing an electrode catalyst layer for a fuel cell, wherein the peroxide decomposition catalyst has a catalytic ability to catalytically decompose peroxide more than the catalyst substance. is there.

The invention according to claim 10 of the present invention is the method for producing an electrode catalyst layer for a fuel cell, wherein the peroxide decomposition catalyst contains a transition metal element.
According to an eleventh aspect of the present invention, the transition metal element is at least one of cerium, manganese, tungsten, zirconium, titanium, vanadium, yttrium, lanthanum, neodymium, nickel, cobalt, ruthenium, chromium, molybdenum, and iron. A method for producing an electrode catalyst layer for a fuel cell, comprising:

The invention according to claim 12 of the present invention is the method for producing an electrode catalyst layer for a fuel cell, wherein the transition metal element is cerium.
Invention is a method for manufacturing a membrane electrode assembly sandwiched between the polymer electrolyte membrane a pair of electrode catalyst layers, one of the pair of electrode catalyst layers, the positive electrode side electrode catalyst according to claim 1 3 of the present invention A layer is manufactured by the manufacturing method of the electrode catalyst layer for fuel cells as described in any one of Claims 1-12, It is a manufacturing method of the membrane electrode assembly for fuel cells characterized by the above-mentioned.

The invention according to claim 1 4 of the present invention sandwiching the membrane electrode assembly manufactured by the method for manufacturing a fuel cell membrane electrode assembly according to claim 1 3 in a pair of gas diffusion layers, the gas diffusion the membrane electrode assembly was sandwiched with a layer which is the production method of the polymer electrolyte fuel cell according to holding to said Rukoto a pair of separators.

According to the present invention, in an electrode catalyst layer including a catalyst substance, carbon particles, a peroxide decomposition catalyst, and a polymer electrolyte, the polymer electrolyte is embedded in a catalyst substance having a specific surface area smaller than that of the carbon particles. increasing the reaction activity points by increasing the proton conductivity of the surface, a method of manufacturing a preparation lateral Honami Binimaku electrode assembly of improved electrode catalyst layer of the output performance, to provide a method of manufacturing a polymer electrolyte fuel cell be able to.

Moreover, the polymer electrolyte is embedded in carbon particles having a specific surface area larger than that of the catalyst material, and a process for reducing the specific surface area of the carbon particles is performed. By adjusting the specific surface area of the carbon particles, the proton conductivity on the surface of the catalyst can be increased when the electrode catalyst layer is formed. As a result, it is possible to react the active point is increased, a manufacturing method of manufacturing side Honami Binimaku electrode assembly of improved electrode catalyst layer of the output performance, to provide a method of manufacturing a polymer electrolyte fuel cell.

In addition, hydrogen peroxide and hydrogen peroxide radicals can be effectively decomposed by dispersing the peroxide decomposition catalyst in the vicinity of the catalyst substance and making it catalytic ability to catalytically decompose the peroxide rather than the catalyst substance. . As a result, it is possible to suppress damage to the electrode catalyst, a method of manufacturing a preparation lateral Honami Binimaku electrode assembly of durability improved electrocatalyst layer, it is possible to provide a manufacturing method of the polymer electrolyte fuel cell it can.

Schematic cross-sectional view of a membrane electrode assembly according to the present invention Exploded sectional view of a polymer electrolyte fuel cell according to the present invention

  Below, the membrane electrode assembly which concerns on this invention, its manufacturing method, and a polymer electrolyte fuel cell are demonstrated. The present invention is not limited to the membrane electrode assembly described below, and modifications such as design changes can be added based on the knowledge of those skilled in the art, and such modifications are added. The embodiments are also included in the scope of the present invention.

First, the membrane electrode assembly which concerns on one Embodiment of this invention is demonstrated.
FIG. 1 is a schematic cross-sectional view showing a membrane electrode assembly 12 according to an embodiment of the present invention. As shown in FIG. 1, a membrane electrode assembly 12 according to an embodiment of the present invention includes a polymer electrolyte membrane 1, an electrode catalyst layer 2 on the air electrode side that sandwiches the polymer electrolyte membrane 1, and a fuel electrode. The electrode catalyst layer 3 on the side is provided.

Next, a polymer electrolyte fuel cell according to an embodiment of the present invention will be described.
FIG. 2 is an exploded cross-sectional view of the polymer electrolyte fuel cell 11 according to one embodiment of the present invention. The polymer electrolyte fuel cell 11 includes an air electrode side gas diffusion layer 4 disposed so as to face one electrode catalyst layer 2 of the membrane electrode assembly 12, and the other electrode catalyst layer of the membrane electrode assembly 12. 3 and the gas diffusion layer 5 on the fuel electrode side disposed so as to face the fuel cell 3.
The electrode catalyst layer 2 and the gas diffusion layer 4 constitute an air electrode (cathode) 6, and the electrode catalyst layer 3 and the gas diffusion layer 5 constitute a fuel electrode (anode) 7. In addition, separators 10 made of a conductive and impermeable material are disposed outside the gas diffusion layers 4 and 5, respectively. Each separator 10 includes a gas flow path 8 for gas circulation and cooling for cooling water circulation. The water flow path 9 is provided.

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. An electromotive force can be generated between the fuel electrode and the air electrode by causing an electrode reaction between the fuel gas hydrogen and oxygen gas in the presence of a catalyst.
The solid polymer electrolyte membrane 1, the electrode catalyst layers 2 and 3, and the gas diffusion layers 4 and 5 of the solid polymer fuel cell 11 are sandwiched by a pair of separators 10. The polymer electrolyte fuel cell 11 is a fuel cell having a single cell structure, but a plurality of cells may be stacked via the separator 10 to form a polymer electrolyte fuel cell.

Next, the manufacturing method of the membrane electrode assembly 12 which concerns on one Embodiment of this invention is demonstrated.
The electrode catalyst layer 2 of the membrane electrode assembly 12 according to an embodiment of the present invention is manufactured by a manufacturing method including the following first to fourth steps.
First step: A step of producing a first catalyst ink in which a catalyst material or carbon particles having a specific surface area larger than that of the catalyst material are dispersed in a solvent together with a peroxide decomposition catalyst and a first polymer electrolyte.
Second step: A step of drying the first catalyst ink and embedding the catalyst substance and the peroxide decomposition catalyst or the carbon particles and the peroxide decomposition catalyst with the first polymer electrolyte.

Third step: After adding carbon particles or a catalytic material to the first catalyst ink after the second step, the catalytic material, the carbon particles, the peroxide decomposition catalyst, and the first polymer electrolyte are converted into the second polymer electrolyte. And a step of preparing a second catalyst ink dispersed in a solvent.
Fourth step: A step of forming the electrode catalyst layer 2 by applying the second catalyst ink onto a substrate selected from a gas diffusion layer, a transfer sheet, and a polymer electrolyte membrane.

  The present inventor has shown that the proton conductivity on the catalyst surface is enhanced by drying the first catalyst ink and embedding the catalyst substance with the first polymer electrolyte, thereby increasing the reaction active point. The headline, the present invention has been reached. Therefore, after producing the first catalyst ink in the first step, the catalytic material of the first catalyst ink is embedded in the first polymer electrolyte to increase the proton conductivity of the catalyst surface, thereby increasing the reaction active point. Can be increased.

  In the conventional method for producing an electrode catalyst layer without embedding with the first polymer electrolyte, carbon particles having a large specific surface area are preferentially embedded with the polymer electrolyte when the electrode catalyst layer is formed. The proton conductivity on the surface is low, and the reactive site cannot be increased. In addition, the conventional manufacturing method can also increase the proton conductivity of the catalyst surface by increasing the concentration of the polymer electrolyte, but an excessive amount is added to the carbon particles to improve the output performance. It is difficult.

  In addition, when the first catalyst ink is dried in the second step and the catalyst material is embedded in the first polymer electrolyte, the weight ratio of the dried catalyst material and the first polymer electrolyte is set to the ink ratio. It can be controlled by setting the composition. The weight ratio of the catalyst substance and the first polymer electrolyte is preferably in the range of 1: 0.01 to 1:30. When the weight ratio of the first polymer electrolyte to the catalyst substance is less than 0.01, the proton conductivity on the catalyst surface does not change and it is difficult to increase the reaction active point. Therefore, the output performance may not be improved. In addition, when the weight ratio of the first polymer electrolyte to the catalyst substance exceeds 30, gas diffusibility to the reaction active site may be hindered and output performance may not be improved.

  The inventor added the carbon particles to the first catalyst ink dried in the second step to produce the second catalyst ink, and the catalyst material of the first catalyst ink (first polymer) The catalyst material embedded in the electrolyte) and the added carbon particles were mixed in the absence of a solvent, and then the second catalyst ink was produced, thereby finding that the reactive site was increased, leading to the present invention. . When this step is not performed, the output performance may not be improved because the contact between the catalyst substance and the carbon particles is low and it is difficult to increase the reaction active point.

  Moreover, in said case, it is preferable to provide the process of heat processing after the process of mixing without a solvent. If this step is not performed, the reaction active point may decrease in the step of producing the second catalyst ink. In this heat treatment step, the temperature is preferably 50 ° C. or higher and 180 ° C. or lower. If the drying temperature is less than 50 ° C., the first polymer electrolyte embedding the catalyst substance is dissolved in the solvent in the step of producing the second catalyst ink, and the formed reaction activity The output performance may not improve due to the decrease in points. Further, even when the drying temperature exceeds 180 ° C., the proton conductivity of the first polymer electrolyte embedding the catalyst substance is lowered, and the output performance may not be improved.

  The present inventor can reduce the specific surface area of the carbon particles by embedding the carbon particles having a specific surface area larger than that of the catalyst substance with the first polymer electrolyte, thereby producing the second catalyst ink. In the process, the inventors have found that the proton conductivity on the catalyst surface can be increased and the reaction active points can be increased, and the present invention has been achieved. In the conventional method for producing an electrode catalyst layer without embedding the polymer electrolyte in the carbon particles, the polymer electrolyte is preferentially embedded in the carbon particles having a large specific surface area when the electrode catalyst layer is formed. The proton conductivity on the surface is lowered, and the reaction active site cannot be increased.

  Further, when the first catalyst ink is dried and the carbon particles are embedded with the first polymer electrolyte, the weight ratio of the dried carbon particles to the first polymer electrolyte is determined by setting the ink composition. Can be controlled. The weight ratio between the carbon particles and the first polymer electrolyte is preferably in the range of 1: 0.1 to 1:20. When the weight ratio of the first polymer electrolyte to the carbon particles is less than 0.1, it is difficult to reduce the specific surface area of the carbon particles, and the output performance is not improved. There is. Further, when the weight ratio of the first polymer electrolyte to the carbon particles exceeds 20, an excessive amount is added to the catalyst substance, and the gas diffusibility to the reaction active site is inhibited. Output performance may not be improved.

  The inventor adds a catalyst substance to the first catalyst ink dried in the second step to produce the second catalyst ink, and the carbon particles (first polymer) of the first catalyst ink. The present inventors have found that the reaction active points can be increased by mixing the carbon particles embedded in the electrolyte) and the added catalyst substance without solvent, and then preparing the second catalyst ink, thereby leading to the present invention. If this step is not performed, the output performance may not be improved because the contact between the carbon particles and the catalyst substance is low and it is difficult to increase the reaction active point.

  Moreover, in said case, it is preferable to provide the process of heat processing after the process of mixing without a solvent. If this step is not performed, the reaction active point may decrease in the step of producing the second catalyst ink. In this heat treatment step, the temperature is preferably 50 ° C. or higher and 180 ° C. or lower. When the drying temperature is less than 50 ° C., the first polymer electrolyte embedding the carbon particles is dissolved in the solvent in the step of producing the second catalyst ink, and the formed reaction activity The output performance may not improve due to the decrease in points. Even when the drying temperature exceeds 180 ° C., the proton conductivity of the first polymer electrolyte that embeds the carbon particles may decrease, and the output performance may not be improved.

As the catalyst material according to the present invention, those generally used can be used. In the present invention, a material containing at least one transition metal element selected from tantalum, niobium, titanium, and zirconium, which is used as a positive electrode of a polymer electrolyte fuel cell as a platinum substitute material in an air electrode, can be used.
More preferably, a material obtained by partially oxidizing these transition metal element carbonitrides in an atmosphere containing oxygen can be used. Specifically, it is a substance (TaCNO) obtained by partially oxidizing tantalum carbonitride (TaCN) in an oxygen-containing atmosphere, and its specific surface area is approximately 1 m ² / g or more and 20 m ² / g or less.

The present inventor uses a peroxide decomposition catalyst having a higher catalytic ability to catalytically decompose hydrogen peroxide as a peroxide decomposition catalyst than an electrode catalyst when producing the first catalyst ink in the first step, and a catalytic substance. Alternatively, the inventors have found that dispersing the peroxide decomposition catalyst in the first polymer electrolyte embedding the carbon particles suppresses the damage of the electrode catalyst and improves the durability, leading to the present invention.
As the peroxide decomposition catalyst used in one embodiment of the present invention, those generally used can be used. In the present invention, it is preferable to use a quality having catalytic ability to catalytically decompose a peroxide rather than a catalytic substance.

More preferably, the substance contains a transition metal element, and contains at least one of cerium, manganese, tungsten, zirconium, titanium, vanadium, yttrium, lanthanum, neodymium, nickel, cobalt, ruthenium, chromium, molybdenum, and iron. Can be used.
Specifically, the transition metal element is cerium, which has a high peroxide decomposition action and can be suitably used as long as it is a poorly soluble compound. As the cerium compound, for example, cerium (III) carbonate can be used.

  When embedding the catalyst material of the first catalyst ink and the peroxide decomposition catalyst in the second step with the first polymer electrolyte, the weight ratio of the catalyst material after drying and the peroxide decomposition catalyst is set to the ink ratio. It can be controlled by setting the composition. The weight ratio of the catalyst material to the peroxide decomposition catalyst is preferably in the range of 1: 0.002 to 1: 1.05. When the weight ratio of the peroxide decomposition catalyst to the catalyst substance is less than 0.002, the effect of decomposing the peroxide is reduced, and the durability may not be improved. A value of 0.005 or more is more preferable. In addition, when the weight ratio of the peroxide decomposition catalyst to the catalyst substance exceeds 1.05, proton conductivity may be reduced and output performance may be reduced. More preferably, it is 0.21 or less.

  In the second step, when the carbon particles and the peroxide decomposition catalyst of the first catalyst ink are embedded with the first polymer electrolyte, the weight ratio between the carbon particles after drying and the peroxide decomposition catalyst is set to It can be controlled by setting the ink composition. The weight ratio between the carbon particles and the peroxide decomposition catalyst is preferably in the range of 1: 0.002 to 1: 2.6. When the weight ratio of the peroxide decomposition catalyst to the carbon particles is less than 0.002, the effect of decomposing the peroxide is reduced, and the durability may not be improved. A value of 0.005 or more is more preferable. In addition, when the weight ratio of the peroxide decomposition catalyst to the carbon particles exceeds 2.6, proton conductivity may decrease and output performance may decrease. It is more preferable to set it to 0.6 or less.

Hereinafter, the membrane electrode assembly 12 and the polymer electrolyte fuel cell 11 according to the present invention will be described in more detail.
The polymer electrolyte membrane 1 only needs to have proton conductivity, and a fluorine polymer electrolyte membrane or a hydrocarbon 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., Aciplex (registered trademark) manufactured by Asahi Kasei Co., Ltd., and Gore Select (registered trademark) manufactured by Gore. ) Etc. can be used. As the hydrocarbon polymer electrolyte membrane, electrolyte membranes such as sulfonated polyether ketone, sulfonated polyethersulfone, sulfonated polyetherethersulfone, sulfonated polysulfide, and sulfonated polyphenylene can be used. Among these, a Nafion (registered trademark) material manufactured by DuPont can be suitably used as the polymer electrolyte membrane. As the hydrocarbon polymer electrolyte membrane, electrolyte membranes such as sulfonated polyether ketone, sulfonated polyethersulfone, sulfonated polyetherethersulfone, sulfonated polysulfide, and sulfonated polyphenylene can be used. In particular, as the polymer electrolyte membrane 1, a Nafion (registered trademark) material manufactured by DuPont can be suitably used.

The electrode catalyst layer is formed on both surfaces of the polymer electrolyte membrane using a catalyst ink. The catalyst ink includes at least a polymer electrolyte and a solvent.
The polymer electrolyte contained in the above-described catalyst ink is not particularly limited as long as it has proton conductivity, and the same material as the polymer electrolyte membrane can be used. Fluorine polymer electrolyte, hydrocarbon polymer electrolyte Can be used. As the fluorine-based polymer electrolyte, for example, a Nafion (registered trademark) material manufactured by DuPont can be used. As the hydrocarbon polymer electrolyte, electrolytes such as sulfonated polyether ketone, sulfonated polyethersulfone, sulfonated polyetherethersulfone, sulfonated polysulfide, and sulfonated polyphenylene can be used. In particular, as a fluorine-based polymer electrolyte, a Nafion (registered trademark) material manufactured by DuPont can be suitably used. In consideration of the adhesion between the electrode catalyst layer and the polymer electrolyte membrane, the same material as that of the polymer electrolyte membrane 1 is preferably used.

The polymer electrolyte according to the present invention includes a first polymer electrolyte embedded with a catalyst material or carbon particles, and a second polymer material mixed with the catalyst material or carbon particles embedded with the first polymer electrolyte. However, both may be the same polymer electrolyte or different polymer electrolytes.
Carbon particles are generally used as the carbon particles according to the present invention. The type of carbon particles is not limited as long as they are in the form of fine particles and have conductivity and are not affected by the catalyst, but carbon black, graphite, graphite, activated carbon, carbon fiber, carbon nanotube, fullerene should be used. Can do. If the particle size of the carbon particles is too small, it becomes difficult to form an electron conduction path. If the particle size is too large, the gas diffusibility of the electrode catalyst layers 2 and 3 is reduced, and the utilization factor of the catalyst is reduced. About ~ 1000 nm is preferable. More preferably, 10-100 nm is good.

  The solvent used as a dispersion medium for the catalyst ink is not particularly limited as long as it does not erode the catalyst substance-supporting particles and the polymer electrolyte, and can dissolve or disperse the polymer electrolyte in a highly fluid state as a fine gel. It is not something. However, it is desirable that at least a volatile organic solvent is contained. 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, and tert-butyl alcohol. , Alcohols such as pentaanol, acetone, methyl ethyl ketone, pentanone, methyl isobutyl ketone, heptanone, cyclohexanone, methyl cyclohexanone, acetonyl acetone, diisobutyl ketone and other ketone solvents, tetrahydrofuran, dioxane, diethylene glycol dimethyl ether, anisole, methoxy toluene , Ether solvents such as dibutyl ether, other dimethylformamide, dimethylacetamide, N-methylpyrrolidone, ethylene glycol, diethylene glycol, diacetate Down alcohol, 1 such as a polar solvent such as methoxy-2-propanol can be used. Moreover, you may use what mixed 2 or more types among the above-mentioned solvents.

  In addition, a solvent using a lower alcohol as a solvent used as a dispersion medium of the catalyst ink has a high risk of ignition. Therefore, when using a lower alcohol, it is preferable to use a mixed solvent with water. Furthermore, water that is compatible with the polymer electrolyte may be contained. The amount of water added is not particularly limited as long as the polymer electrolyte does not separate and cause white turbidity or gelation.

The solvent used as the dispersion medium for the catalyst ink includes a solvent for the first catalyst ink and a solvent for the second catalyst ink. Both may be the same solvent or different solvents. Good.
In order to disperse the catalyst material-carrying particles, the catalyst ink may contain a dispersant. Examples of the dispersant include an anionic surfactant, a cationic surfactant, an amphoteric surfactant, and a nonionic surfactant.

  Examples of the anionic surfactant include alkyl ether carboxylate, ether carboxylate, alkanoyl sarcosine, alkanoyl glutamate, acyl glutamate, oleic acid / N-methyl taurine, potassium oleate / diethanolamine salt, alkyl ether sulfate・ Triethanolamine 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, high molecular weight polyether ester acid Amine salt, amine salt of specially modified phosphate ester, high molecular weight polyester acid amidoamine salt, amidoamine salt of special fatty acid derivative, alkylamine salt of higher fatty acid, high molecular weight polycarboxylic acid Amidoamine salts, carboxylic acid type surfactants such as sodium laurate, sodium stearate, sodium oleate, dialkyl sulfosuccinates, dialkyl salts of sulfosuccinic acid, 1,2-bis (alkoxycarbonyl) -1-ethanesulfonic acid Salt, alkyl sulfonate, alkyl sulfonate, paraffin sulfonate, α-olefin sulfonate, linear alkyl benzene sulfonate, alkyl benzene sulfonate, polynaphthyl methane sulfonate, polynaphthyl methane sulfonate, naphthalene sulfonate-formalin condensate, alkyl naphthalene sulfonate Alkanoyl methyl tauride, lauryl sulfate sodium salt, cetyl sulfate sodium salt, stearyl sulfate sodium salt, Sodium yl sulfate ester, lauryl ether sulfate ester, sodium alkylbenzene sulfonate, oil-soluble alkylbenzene sulfonate, α-olefin sulfonate and other surfactants, alkyl sulfate ester, alkyl sulfate, alkyl sulfate , Sulfate ether type surfactants such as alkyl ether sulfate, polyoxyethylene alkyl ether sulfate, alkyl polyethoxy sulfate, polyglycol ether sulfate, alkyl polyoxyethylene sulfate, sulfated oil, highly sulfated oil, phosphoric acid ( Mono- or di) alkyl salts, (mono- or di) alkyl phosphates, (mono- or di) alkyl phosphate esters, alkyl polyoxyethylene phosphates, alkyl ether phosphates, Kill polyethoxy phosphate, polyoxyethylene alkyl ether, alkylphenyl phosphate polyoxyethylene salt, alkylphenyl ether phosphate, alkylphenyl polyethoxy phosphate, polyoxyethylene alkylphenyl ether phosphate, high grade Examples thereof include phosphate type surfactants such as alcohol phosphate monoester disodium salt, higher alcohol phosphate disodium disodium salt, and zinc dialkyldithiophosphate.

  Examples of the cationic surfactant include benzyldimethyl {2- [2- (P-1,1,3,3-tetramethylbutylphenoxy) ethoxy] ethyl} ammonium chloride, octadecylamine acetate, tetradecylamine. Acetate, octadecyltrimethylammonium chloride, tallow trimethylammonium chloride, dodecyltrimethylammonium chloride, coconut trimethylammonium chloride, hexadecyltrimethylammonium chloride, behenyltrimethylammonium chloride, coconut dimethylbenzylammonium chloride, tetradecyldimethylbenzylammonium chloride, octadecyldimethylbenzyl Ammonium chloride, dioleyldimethylammonium chloride, 1-hydride Xyethyl-2-tallow imidazoline quaternary salt, 2-heptadecenyl-hydroxyethyl imidazoline, stearamide ethyl diethylamine acetate, stearamide ethyl diethylamine hydrochloride, triethanolamine monostearate formate, alkyl pyridium salt, higher alkyl Examples include amine ethylene oxide adducts, polyacrylamide amine salts, modified polyacrylamide amine salts, and perfluoroalkyl quaternary ammonium iodides.

  Examples of the amphoteric surfactant include dimethyl coconut betaine, dimethyl lauryl betaine, sodium laurylaminoethylglycine, sodium laurylaminopropionate, stearyl dimethyl betaine, lauryl dihydroxyethyl betaine, amide betaine, imidazolinium betaine, lecithin, 3 -[Ω-fluoroalkanoyl-N-ethylamino] -1-propanesulfonic acid sodium, N- [3- (perfluorooctanesulfonamido) propyl] -N, N-dimethyl-N-carboxymethyleneammonium betaine It is done.

  Examples of the nonionic surfactant include coconut fatty acid diethanolamide (1: 2 type), coconut fatty acid diethanolamide (1: 1 type), bovine fatty acid diethanolamide (1: 2 type), and bovine fatty acid diethanolamide (1). : 1 type), oleic acid diethanolamide (1: 1 type), hydroxyethyl lauryl amine, polyethylene glycol lauryl amine, polyethylene glycol palm amine, polyethylene glycol stearyl amine, polyethylene glycol beef tallow amine, polyethylene glycol beef tallow propylene diamine, polyethylene glycol di Oleylamine, dimethyllaurylamine oxide, dimethylstearylamine oxide, dihydroxyethyllaurylamine oxide, perfluoroalkylamine oxide, poly Nylpyrrolidone, higher alcohol ethylene oxide adduct, alkylphenol ethylene oxide adduct, fatty acid ethylene oxide adduct, polypropylene glycol ethylene oxide adduct, fatty acid ester of glycerin, fatty acid ester of pentaerythritol, fatty acid ester of sorbit, fatty acid ester of sorbitan And fatty acid esters of sugar.

  Among the above 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. Can be suitably used as a dispersant in consideration of the carbon dispersion effect, the change in catalyst performance due to the remaining of the dispersant, and the like.

  Further, the catalyst ink is subjected to a dispersion treatment as necessary. The viscosity of the catalyst ink and the size of the particles can be controlled by the conditions for the dispersion treatment of the catalyst ink. Distributed processing can be performed using various apparatuses. In particular, the distributed processing method is not limited. For example, as the dispersion treatment, treatment with a ball mill or roll mill, treatment with a shear mill, treatment with a wet mill, ultrasonic dispersion treatment, and the like can be given. Moreover, you may employ | adopt the homogenizer etc. which stir with centrifugal force.

  If the solid content in the catalyst ink is too large, the viscosity of the catalyst ink becomes high, so that the electrode catalyst layer surfaces 2 and 3 are likely to crack. 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 to 50% by mass. Moreover, although solid content consists of a catalyst substance, a carbon particle, a peroxide decomposition catalyst, and a polymer electrolyte, if content of carbon particle is increased among solid content, even if it is the same solid content content, a viscosity will become high. On the other hand, when the content of carbon particles in the fixed portion is reduced, the viscosity is lowered even with the same solid content. Therefore, the proportion of carbon particles in the solid content is preferably 10 to 80 wt%. The viscosity of the catalyst ink is preferably about 0.1 to 500 cP (0.0001 to 0.5 Pa · s), more preferably 5 to 100 cP (0.005 to 0.1 Pa · s). Further, the viscosity can be controlled by adding a dispersing agent when the catalyst ink is dispersed.

Further, the catalyst ink may contain a pore forming agent. By removing the pore-forming agent after the formation of the electrode catalyst layer, 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 pore-forming agent is a substance that is soluble in warm 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 acid-soluble inorganic salts such as calcium carbonate, barium carbonate, magnesium carbonate, magnesium sulfate, and magnesium oxide, inorganic salts soluble in alkaline aqueous solutions such as alumina, silica gel, and silica sol, aluminum Metals soluble in acids or alkalis such as 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, polyethylene glycol And water-soluble organic compounds such as Moreover, although the said pore making agent may be used individually by 1 type or in combination of 2 or more types, it is preferable to use in combination of 2 or more types.

  In the method for producing an electrode catalyst layer according to the present invention, the catalyst material or carbon particles embedded with the first polymer electrolyte is a first material in which the catalyst material or carbon particles and the first polymer electrolyte are dispersed in a solvent. It is obtained by applying a catalyst ink to a transfer sheet and drying it. Alternatively, the catalyst material or carbon particles embedded in the polymer electrolyte can be directly obtained by spraying in a dry atmosphere.

  In the method for producing an electrode catalyst layer of the present invention, a second catalyst ink in which a catalyst material and carbon particles embedded with a first polymer electrolyte and a second polymer electrolyte are dispersed in a second solvent, Or a step of producing an electrode catalyst layer from a second catalyst ink in which carbon particles and a catalyst substance embedded with a first polymer electrolyte and a second polymer electrolyte are dispersed in a second solvent. In this case, the catalyst ink is applied onto a substrate, and an electrode catalyst layer is formed through a drying process. When a gas diffusion layer or a transfer sheet is used as the substrate, the electrode catalyst layers are bonded to both surfaces of the polymer electrolyte membrane by a bonding process. In the membrane / electrode assembly of the present invention, a polymer electrolyte membrane is used as a base material, a catalyst ink is directly applied to both sides of the polymer electrolyte membrane, and an electrode catalyst layer is directly formed on both sides of the polymer electrolyte membrane. You can also

At this time, a doctor blade method, a dipping method, a screen printing method, a roll coating method, a spray method, or the like can be adopted as a coating method for coating the catalyst ink on the substrate. For example, spraying methods such as pressure spraying, ultrasonic spraying, and electrostatic spraying are not likely to agglomerate when the coated catalyst ink is dried, resulting in a homogeneous and highly porous catalyst layer. Is preferable.
As a substrate in the production of the electrode catalyst layer, a gas diffusion layer, a transfer sheet, or a polymer electrolyte membrane can be used.

  The transfer sheet used as the substrate may be any material having good transferability. For example, ethylene tetrafluoroethylene copolymer (ETFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoropar A fluororesin such as a fluoroalkyl vinyl ether copolymer (PFA) or polytetrafluoroethylene (PTFE) can be used. In addition, polyimide, polyethylene terephthalate, polyamide (nylon), polysulfone, polyethersulfone, polyphenylene sulfide, polyether ether ketone, polyetherimide, polyarylate, polyethylene naphthalate, polymer sheets and polymer films are transferred. It can be used as a sheet. When a transfer sheet is used as the substrate, the electrode sheet is peeled after the electrode catalyst layer is bonded to the polymer electrolyte membrane 1, and the membrane electrode assembly is provided with electrode catalyst layers on both sides of the polymer electrolyte membrane 1. Twelve.

  As the gas diffusion layer, a material having gas diffusibility and conductivity can be used. For example, porous carbon materials such as carbon cloth, carbon paper, and nonwoven fabric can be used. The gas diffusion layer can also be used as a substrate on which the catalyst ink is applied. When the gas diffusion layer is used as a substrate on which the catalyst ink is applied, it is not necessary to peel off the substrate that is the gas diffusion layer after the electrode catalyst layer is bonded to the polymer electrolyte membrane.

  When the gas diffusion layer is used as a substrate on which the catalyst ink is applied, an eye layer may be formed on the gas diffusion layer in advance before the catalyst ink is applied to the gas diffusion layer. The mesh layer is a layer that prevents the catalyst ink from permeating into the gas diffusion layer, and deposits on the mesh layer to form a three-phase interface even when the coating amount of the catalyst ink is small. The filler layer can be formed, for example, by dispersing carbon particles in a fluorine resin solution and sintering at a temperature equal to or higher than the melting point of the fluorine resin. As the fluororesin, polytetrafluoroethylene (PTFE) or the like can be used.

As the separator, a carbon type or a metal type can be used. Note that the gas diffusion layer and the separator may have an integral structure. When the separator or the electrode catalyst layer functions as a gas diffusion layer, the gas diffusion layer may be omitted. The polymer electrolyte fuel cell 11 can be manufactured by assembling other accompanying devices such as a gas supply device and a cooling device.
The method for producing an electrode catalyst layer for a polymer electrolyte fuel cell according to the present invention will be described below with reference to specific examples and comparative examples, but the present invention is not limited to the following examples.

[Preparation of first catalyst ink]
Catalyst substance (TaCNO, specific surface area 12 m ² / g), peroxide decomposition catalyst (cerium (III) carbonate), and 20% by mass polymer electrolyte solution (trade name: Nafion (registered trademark), manufactured by DuPont) The mixture was mixed and dispersed with a ball mill. Ball mill pots and balls made of zirconia were used. The composition ratio of the catalyst ink was 1: 0.05: 0.25 in terms of the mass ratio of the catalyst substance, the peroxide decomposition catalyst, and the polymer electrolyte. The solvent was ultrapure water, 1-propanol in a volume ratio of 1: 1, and the solid content was 14% by mass. A PTFE sheet was used as a substrate for drying the first catalyst ink.

[Method of forming catalyst material and peroxide decomposition catalyst embedded in polymer electrolyte]
The first catalyst ink was applied onto the substrate by a doctor blade and dried at 80 ° C. for 5 minutes in an air atmosphere. Thereafter, the catalyst material embedded in the polymer electrolyte and the peroxide decomposition catalyst were recovered from the substrate.

[Mixing and heat treatment of catalyst material embedded in polymer electrolyte, peroxide decomposition catalyst, and carbon particles]
A catalyst material embedded in a polymer electrolyte, a peroxide decomposition catalyst, and carbon particles (Ketjen Black, trade name: EC-300J, manufactured by Lion Corporation, specific surface area 800 m ² / g) were mixed in a ball mill without solvent. . Ball mill pots and balls made of zirconia were used. The composition ratio of the catalyst material embedded in the polymer electrolyte, the peroxide decomposition catalyst, and the carbon particles was 1: 0.05: 1 by mass ratio.

[Preparation of second catalyst ink]
A catalyst material embedded in a polymer electrolyte, a peroxide decomposition catalyst, a mixture of carbon particles and a heat treatment, and a 20% by mass polymer electrolyte solution were mixed in a solvent, and dispersed by a ball mill. . Ball mill pots and balls made of zirconia were used. The composition ratio of the catalyst ink was such that the mass ratio of the catalyst substance and peroxide decomposition catalyst, the carbon particles, and the polymer electrolyte was 1: 0.05: 1: 0.8 was used as the second catalyst ink. The solvent was ultrapure water, 1-propanol in a volume ratio of 1: 1, and the solid content was 14% by mass. A PTFE sheet was used as a transfer sheet.

[Method for forming electrode catalyst layer]
The second catalyst ink was applied to the transfer sheet with a doctor blade, and dried at 80 ° C. for 5 minutes in an air atmosphere. The thickness of the electrode catalyst layer was adjusted so that the amount of the catalyst substance supported was 0.4 mg / cm ^2, and the electrode catalyst layer 2 on the air electrode side was formed.

[Preparation of first catalyst ink]
Carbon particles (Ketjen Black, trade name: EC-300J, manufactured by Lion, specific surface area 800 m ² / g), peroxide decomposition catalyst (cerium (III) carbonate), and 20% by mass polymer electrolyte solution (Nafion: registered) (Trademark, manufactured by DuPont) was mixed in a solvent, and dispersed with a ball mill. Ball mill pots and balls made of zirconia were used. The composition ratio of the catalyst ink was 1: 0.05: 0.5 in terms of the mass ratio of carbon particles, peroxide decomposition catalyst, and polymer electrolyte. The solvent was ultrapure water, 1-propanol in a volume ratio of 1: 1, and the solid content was 14% by mass. A PTFE sheet was used as a substrate for drying the first catalyst ink.

[Method of forming carbon particles embedded in polymer electrolyte and peroxide decomposition catalyst]
The first catalyst ink was applied onto the substrate by a doctor blade and dried at 80 ° C. for 5 minutes in an air atmosphere. Thereafter, the carbon particles embedded in the polymer electrolyte and the peroxide decomposition catalyst were recovered from the substrate.

[Mixing and heat treatment of carbon particles embedded in polymer electrolyte, peroxide decomposition catalyst, and catalyst material]
Carbon particles embedded with a polymer electrolyte, a peroxide decomposition catalyst, and a catalyst material (TaCNO, specific surface area 12 m ² / g) were mixed in a ball mill without solvent. Ball mill pots and balls made of zirconia were used. The composition ratio of the carbon particles, the peroxide decomposition catalyst, and the catalyst material was 1: 0.05: 1 by mass ratio.

[Preparation of second catalyst ink]
A mixture of carbon particles embedded in a polymer electrolyte, a peroxide decomposition catalyst, and a catalyst material, and heat treatment, and a 20% by mass polymer electrolyte solution were mixed in a solvent, and dispersion treatment was performed using a ball mill. . Ball mill pots and balls made of zirconia were used. The composition ratio of the catalyst ink was such that the mass ratio of the catalyst substance and peroxide decomposition catalyst, the carbon particles, and the polymer electrolyte was 1: 0.05: 1: 0.8 was used as the second catalyst ink. The solvent was ultrapure water, 1-propanol in a volume ratio of 1: 1, and the solid content was 14% by mass. A PTFE sheet was used as a transfer sheet.

[Method for forming electrode catalyst layer]
The second catalyst ink was applied to the transfer sheet with a doctor blade, and dried at 80 ° C. for 5 minutes in an air atmosphere. The thickness of the electrode catalyst layer was adjusted so that the amount of the catalyst substance supported was 0.4 mg / cm ^2, and the electrode catalyst layer 2 on the air electrode side was formed.

Comparative example

[Preparation of catalyst ink]
The catalyst material, carbon particles, and a 20% by mass polymer electrolyte solution were mixed in a solvent and subjected to dispersion treatment with a ball mill. Ball mill pots and balls made of zirconia were used. The composition ratio of the catalyst ink was such that the mass ratio of the catalyst substance, the carbon particles, and the polymer electrolyte was 1: 1: 0.8. The solvent used was ultrapure water and 1-propanol in a volume ratio of 1: 1. The solid content was 14% by mass. As the substrate, the same transfer sheet as in Example 1 and Example 2 was used.

[Method for producing electrode catalyst layer]
In the same manner as in Example 1 and Example 2, the catalyst ink was applied to the transfer sheet and dried. The thickness of the electrode catalyst layer was adjusted so that the amount of the catalyst substance supported was 0.4 mg / cm ^2, and the electrode catalyst layer 2 on the air electrode side was formed.

[Preparation of electrode catalyst layer for fuel electrode]
A platinum-supported carbon catalyst (trade name: TEC10E50E, manufactured by Tanaka Kikinzoku Kogyo Co., Ltd.) having a platinum-supporting amount of 50% by mass and a 20% by mass polymer electrolyte solution were mixed in a solvent and subjected to dispersion treatment with a ball mill. A catalyst ink having a dispersion time of 60 minutes was used. The composition ratio of the catalyst ink was 1: 1 in the mass ratio of carbon in the platinum-supported carbon and the polymer electrolyte, and the solvent was ultrapure water and 1-propanol in a volume ratio of 1: 1. The solid content was 10% by mass. In the same manner as in the electrode catalyst layer 2, the catalyst ink was applied to the substrate and dried. The thickness of the electrode catalyst layer was adjusted so that the amount of catalyst material supported was 0.3 mg / cm ^2, and the electrode catalyst layer 3 on the fuel electrode side was formed.

(Production of membrane electrode assembly)
The base material on which the air electrode side electrode catalyst layer 2 and the base material on which the fuel electrode side electrode catalyst layer 3 formed in Example 1, Example 2 and Comparative Example were formed were punched into a square of 5 cm ^2. A transfer sheet is placed so as to face both surfaces of a molecular electrolyte membrane (trade name: Nafion (registered trademark), manufactured by DuPont), and hot pressing is performed at 130 ° C. for 10 minutes to form a membrane electrode assembly 12. Obtained. Carbon papers 4 and 5 each having a sealing layer formed as a gas diffusion layer are disposed on both surfaces of the membrane electrode assembly 12 thus obtained, and are further sandwiched between a pair of separators 10 to provide a single cell solid polymer fuel. A battery was produced.

(Evaluation)
[Evaluation conditions]
Using a fuel cell measurement device, power generation characteristics were evaluated at a cell temperature of 80 ° C. and under conditions of 100% RH for both the anode and the cathode. Using pure hydrogen as the fuel gas and pure oxygen as the oxidant gas, the flow rate was controlled at a constant flow rate.

(Measurement result)
The membrane electrode assemblies produced in Example 1 and Example 2 showed power generation performance superior to the membrane electrode assemblies produced in Comparative Examples. In particular, the power generation performance in the vicinity of 0.6 V was improved. Example 1 showed power generation performance of about 1.9 times that of the comparative example, and Example 2 showed power generation performance of about 2.0 times that of the comparative example. This is presumed that in Example 1, the proton conductivity on the surface of the catalyst was increased by embedding the catalyst material with the polymer electrolyte, and the reaction active points increased. In Example 2, it was presumed that the proton conductivity on the catalyst surface was increased by adjusting the specific surface area of the carbon particles, and the reaction active points were increased. In contrast, in the comparative example, the catalyst material, the carbon particles, and the polymer electrolyte are dispersed in the solvent in one step, so that the polymer electrolyte is preferentially adsorbed on the carbon particles having a larger specific surface area than the catalyst material. As a result, it was assumed that sufficient proton conductivity was not ensured on the surface of the catalyst material.

Moreover, the membrane electrode assembly produced in Example 1 and Example 2 showed durability superior to the membrane electrode assembly produced in the comparative example. As a result of performing the operation evaluation for 100 hours at 0.1 mA / cm ² , the cell voltage of Example 1 and Example 2 did not change, whereas the cell voltage of the comparative example decreased by 54 mV. In Example 1 and Example 2, it was assumed that the hydrogen peroxide produced by the reaction was decomposed by the peroxide decomposition catalyst, and the electrode catalyst was not damaged. On the other hand, in the comparative example, it was guessed that the electrode catalyst was damaged by the hydrogen peroxide generated by the reaction, and the battery performance was lowered.

  The present invention relates to a method for producing a polymer electrolyte and an electrode catalyst layer comprising a catalyst substance, carbon particles, and a peroxide decomposition catalyst, wherein the polymer electrolyte is embedded in a catalyst substance having a specific surface area smaller than that of the carbon particles. It is characterized by including the process to perform. By increasing the proton conductivity on the catalyst surface, the reaction active point can be increased, and a polymer electrolyte fuel cell with improved output performance can be provided.

  The present invention also relates to a method for producing a polymer electrolyte and an electrode catalyst layer comprising a catalyst substance, carbon particles, and a peroxide decomposition catalyst, wherein the polymer electrolyte is applied to carbon particles having a specific surface area larger than that of the catalyst substance. The method includes a step of embedding. By performing the treatment for reducing the specific surface area of the carbon particles, the proton conductivity on the catalyst surface can be increased when the electrode catalyst layer is formed. As a result, it is possible to provide a method for producing an electrode catalyst layer, an electrode catalyst layer, a membrane electrode assembly, and a polymer electrolyte fuel cell with increased reaction active points and improved output performance.

The present invention also relates to a method for producing an electrode catalyst layer comprising a polymer electrolyte, a catalyst material, carbon particles, and a peroxide decomposition catalyst, wherein the peroxide decomposition catalyst is dispersed in the vicinity of the catalyst material, Hydrogen peroxide and hydrogen peroxide radicals can be effectively decomposed by making the peroxide catalytic ability to catalytically decompose. As a result, damage to the electrode catalyst can be suppressed, and a method for producing an electrode catalyst layer with improved durability, an electrode catalyst layer, a membrane electrode assembly, and a polymer electrolyte fuel cell can be provided.
In the electrocatalyst layer using an oxide-based non-platinum catalyst as the catalyst material, the potential of the catalyst material can be extracted and the durability improved compared to the conventional manufacturing method. High utility value.

DESCRIPTION OF SYMBOLS 1 Solid 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)
8 Gas flow path 9 Cooling water flow path 10 Separator 11 Polymer electrolyte fuel cell 12 Membrane electrode assembly

Claims (14)

Catalyst material, carbon particles, wherein the peroxide decomposition catalyst and the polymer electrolyte, and a method of specific surface area of the catalytic material to produce a small fuel cell electrode catalyst layer than the carbon particles,
A first step of producing a first catalyst ink in which the catalyst substance or the carbon particles are dispersed in a solvent together with the peroxide decomposition catalyst and the first polymer electrolyte;
A second step of drying the first catalyst ink and embedding the catalyst substance and the peroxide decomposition catalyst or the carbon particles and the peroxide decomposition catalyst with the first polymer electrolyte;
After adding carbon particles or a catalyst substance to the first catalyst ink dried in the second step, the catalyst substance, the carbon particles, the peroxide decomposition catalyst, and the first polymer electrolyte are added to the second catalyst ink. A third step of producing a second catalyst ink dispersed in a solvent together with the polymer electrolyte of
And a fourth step of forming the electrode catalyst layer by applying the second catalyst ink onto a substrate selected from a gas diffusion layer, a transfer sheet, and a polymer electrolyte membrane. For producing an electrode catalyst layer for use.   The weight ratio of the catalyst material to the first polymer electrolyte is in the range of 1: 0.01 to 1:30, or the weight ratio of the carbon particles to the first polymer electrolyte is 1: 0.1. 2. The method for producing a fuel cell electrode catalyst layer according to claim 1, wherein the first catalyst ink is dried in the second step so as to be in a range of ˜1: 20.   3. The method for producing an electrode catalyst layer for a fuel cell according to claim 1, wherein the first catalyst ink is dried at a temperature of 30 ° C. or more and 140 ° C. or less in the second step.   After adding carbon particles or a catalyst substance to the first catalyst ink dried in the second step and mixing without solvent, the catalyst substance, the carbon particles, the peroxide decomposition catalyst, and the first catalyst ink are added. A fuel cell electrode catalyst layer according to any one of claims 1 to 3, wherein a second catalyst ink is prepared by dispersing the polymer electrolyte together with the second polymer electrolyte in a solvent. Production method.   Carbon particles or a catalyst material is added to the first catalyst ink dried in the second step and mixed without solvent, and then the catalyst material or carbon particles embedded with the first polymer electrolyte The added carbon particles or catalyst material is heat-treated at a temperature of 50 ° C. or more and 180 ° C. or less, and then the catalyst material, the carbon particles, the peroxide decomposition catalyst, and the first polymer electrolyte are added to the second high-temperature electrolyte. The method for producing a fuel cell electrode catalyst layer according to claim 4, wherein the second catalyst ink dispersed in a solvent together with the molecular electrolyte is prepared.   The catalyst material is an electrode active material for an oxygen reduction electrode used as a positive electrode of a polymer electrolyte fuel cell, and contains at least one transition metal element selected from tantalum, niobium, titanium, and zirconium. The manufacturing method of the electrode catalyst layer for fuel cells as described in any one of Claims 1-5 characterized by the above-mentioned.   7. The method for producing an electrode catalyst layer for a fuel cell according to claim 6, wherein the catalyst material is obtained by partially oxidizing the carbonitride of the transition metal element in an atmosphere containing oxygen.   The method for producing an electrode catalyst layer for a fuel cell according to claim 7, wherein the transition metal element is tantalum.   The production of an electrode catalyst layer for a fuel cell according to any one of claims 1 to 8, wherein the peroxide decomposition catalyst has a catalytic ability to catalytically decompose peroxides more than the catalyst substance. Method.   The method for producing an electrode catalyst layer for a fuel cell according to claim 9, wherein the peroxide decomposition catalyst contains a transition metal element.   The transition metal element includes at least one of cerium, manganese, tungsten, zirconium, titanium, vanadium, yttrium, lanthanum, neodymium, nickel, cobalt, ruthenium, chromium, molybdenum, and iron. The manufacturing method of the electrode catalyst layer for fuel cells of description.   12. The method for producing an electrode catalyst layer for a fuel cell according to claim 11, wherein the transition metal element is cerium. It is a manufacturing method of the membrane electrode assembly which pinched | interposed the polymer electrolyte membrane with a pair of electrode catalyst layer, Comprising: The electrode catalyst layer by the side of a positive electrode among the said pair of electrode catalyst layers is any one of Claims 1-12. A method for producing a membrane electrode assembly for a fuel cell, which is produced by the method for producing an electrode catalyst layer for a fuel cell described in 1 . The membrane electrode assembly produced by the manufacturing method of the fuel cell membrane electrode assembly according to claim 1 3 holding a pair of gas diffusion layers, said membrane electrode assembly was sandwiched with the gas diffusion layer holding to the production method of the polymer electrolyte fuel cell, wherein Rukoto a pair of separators.

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