JP2018181671A - Method for manufacturing membrane-electrode assembly - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a membrane-electrode assembly, by which a membrane-electrode assembly superior in the shape of a polymer electrolyte film and the shape of a catalyst layer can be manufactured readily.SOLUTION: A method for manufacturing a membrane-electrode assembly is one arranged so that a catalyst layer is disposed on each face of a solid polymer electrolyte film. The method comprises: a formation step of forming, on the solid polymer electrolyte film, a solvent permeation preventive layer made of a material which causes phase separation when a slurry for a catalyst layer, arranged to form the catalyst layer is included at 25 mass% or more; a coating step of coating the solvent permeation preventive layer with the slurry for a catalyst layer; and a drying step of drying a structure arranged by coating the solvent permeation preventive layer on the polymer electrolyte film with the slurry for a catalyst layer.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method of manufacturing a membrane electrode assembly. In particular, the present invention relates to a technique suitable for producing a polymer electrolyte fuel cell.

  In recent years, fuel cells have attracted attention as effective solutions for environmental problems and energy problems. In a fuel cell, a fuel such as hydrogen is oxidized using an oxidant such as oxygen, and the chemical energy accompanying this is converted into electrical energy. Fuel cells are classified into alkaline type, phosphoric acid type, solid polymer type, molten carbonate type, solid oxide type and the like according to the type of electrolyte. Solid polymer fuel cells (PEFCs) are expected to be used as portable power sources, household power sources, and automotive power sources because of their low-temperature operation and high output density, and because they can be made smaller and lighter. ing.

A polymer electrolyte fuel cell (PEFC) has a structure in which a polymer electrolyte membrane, which is an electrolyte, is sandwiched between a fuel electrode (anode) and an air electrode (cathode). Fuel gas containing hydrogen on the fuel electrode side, air Electric power is generated by the following electrochemical reaction by supplying an oxidant gas containing oxygen to the electrode side.
Anode: H ₂ → 2 H ⁺ + 2 e ⁻ (1)
Cathode: _1/2 O ₂ + 2 H ⁺ + 2 e ⁻ → H ₂ O (2)

  The anode and the cathode each comprise a laminated structure of a catalyst layer and a gas diffusion layer. The fuel gas supplied to the anode side catalyst layer becomes protons and electrons by the electrode catalyst (reaction 1). The protons move to the cathode through the polymer electrolyte in the anode side catalyst layer and the solid polymer electrolyte membrane. Electrons travel through the external circuit to the cathode. In the cathode side catalyst layer, protons, electrons, and an oxidant gas supplied from the outside react to generate water (reaction 2). In this way, electrons are generated by passing through an external circuit.

Conventionally, as a method for producing a membrane electrode assembly, a slurry for catalyst layer comprising carbon particles carrying a catalyst, a polymer electrolyte and a solvent is prepared, and the slurry for catalyst layer is directly coated on the polymer electrolyte membrane. There is known a method of manufacturing, and a method of forming a transfer base material or a gas diffusion layer and then thermocompression bonding to a polymer electrolyte membrane.
A method of manufacturing a membrane electrode assembly by directly applying a slurry for catalyst layer to a polymer electrolyte membrane by producing a membrane electrode assembly is a membrane having good adhesion of the interface between the polymer electrolyte membrane and the catalyst layer, and excellent power generation performance and durability. An electrode assembly can be produced.

However, in the conventional production method, when the slurry for catalyst layer is directly coated on the polymer electrolyte membrane, the polymer electrolyte membrane swells with the solvent of the electrode slurry during coating and shrinks during drying. This causes problems such as generation of wrinkles in the membrane electrode assembly and generation of cracks in the catalyst layer.
With respect to the said subject, in patent document 1, 2, the method of carrying out adsorption | suction fixation of the polymer electrolyte membrane, and coating the slurry for catalyst layers is proposed. Further, Patent Document 3 proposes a method of wetting a polymer electrolyte membrane before coating.

JP 2004-351413 A Patent No. 5920479 gazette JP 2007-48557 A

  In Patent Documents 1 and 2, swelling of the polymer electrolyte membrane at the time of coating is suppressed by adsorption and fixation, and no wrinkles are generated in the membrane electrode assembly, but sufficient suppression of the generation of cracks in the catalyst layer is Can not. In addition, although it is possible to suppress the occurrence of cracks in the catalyst layer by coating the slurry for the catalyst layer, the process is complicated and the manufacturing cost is increased.

Moreover, in patent document 3, although swelling of the polymer electrolyte membrane at the time of coating can be suppressed, the shrinkage | contraction at the time of drying can not be suppressed. In addition, although the swelling state is to be controlled by the solvent content of the polymer electrolyte membrane, the solvent of the slurry for the catalyst layer is dyed into the polymer electrolyte membrane at the time of coating, so the swelling state can be controlled. Therefore, the above problems can not be solved.
The present invention has been made in view of such circumstances, and it is a method of manufacturing a membrane electrode assembly capable of easily manufacturing a membrane electrode assembly excellent in the shape of a polymer electrolyte membrane and a catalyst layer. Intended to provide.

  In order to solve the above-mentioned subject, a manufacturing method of a membrane electrode assembly concerning one mode of the present invention is a manufacturing method of a membrane electrode assembly by which a catalyst layer is arranged on both sides of a solid polymer electrolyte membrane, Forming a solvent permeation preventing layer made of a material that is phase separated when the slurry for the catalyst layer for forming the catalyst layer is contained in an amount of 25% by mass or more on the solid polymer electrolyte membrane; Applying a slurry for catalyst layer on the prevention layer, and drying the structure formed by applying the slurry for the solvent permeation prevention layer and the catalyst layer on the polymer electrolyte membrane; , And is characterized.

  According to one aspect of the present invention, a membrane electrode assembly excellent in the shape of a polymer electrolyte membrane and a catalyst layer can be easily manufactured and provided.

It is a flowchart which shows the manufacturing method of the membrane electrode assembly concerning embodiment of this invention to process order. It is explanatory drawing of one Embodiment of the manufacturing method of the membrane electrode assembly of this invention. It is explanatory drawing of one Embodiment of the manufacturing method of the membrane electrode assembly of this invention. It is explanatory drawing of one Embodiment of the manufacturing method of the membrane electrode assembly of this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which shows the structural example of the membrane electrode assembly which concerns on embodiment of this invention. FIG. 2 is an exploded cross-sectional view showing a configuration example of a single cell of a polymer electrolyte fuel cell equipped with a membrane electrode assembly.

  Hereinafter, the present invention will be described in detail. The present invention can not be limited to the embodiments described below, and modifications such as changes in design can be added based on the knowledge of those skilled in the art, and such modifications can be added. The embodiments are also included in the scope of the present invention. FIG. 1 is a flowchart showing the method of manufacturing a membrane electrode assembly according to the embodiment of the present invention in the order of steps.

As shown in FIG. 1, in the method of manufacturing a membrane electrode assembly according to the embodiment of the present invention (hereinafter, this embodiment), a solid polymer electrolyte membrane (hereinafter, polymer electrolyte membrane) is prepared. A step of forming a solvent permeation prevention layer on both sides of the molecular electrolyte membrane (step S50), and a coating step of applying a slurry for catalyst layer on both sides of the solid polymer electrolyte membrane on which the solvent permeation prevention layer is formed Step S60), and a drying step (Step S70) of drying the coated slurry for a catalyst layer and the polymer electrolyte membrane as the base thereof. The drying step is a step of drying the entire structure in which the slurry for the solvent permeation prevention layer and the catalyst layer is formed on the polymer electrolyte membrane. The two sides refer to the front and back sides.
The above forming step and the coating step may be performed on one side or on both sides simultaneously. In addition, the drying step may be performed every time the forming step and the coating step are performed on one side, or the drying step may be performed after the forming step and the coating step on both sides.

In the present embodiment, as the material of the solvent permeation preventing layer, a material which is phase separated when the slurry for the catalyst layer is contained in 25% by mass or more, and a material which can be volatilized and removed by drying is selected. Here, the material that phase separates when the catalyst layer slurry is contained in an amount of 25% by mass or more is a material that is immiscible with or less miscible with the catalyst layer slurry.
The fact that the solvent contained in the slurry for the catalyst layer is prevented from soaking into the polymer electrolyte membrane during coating of the slurry for the catalyst layer by the solvent permeation preventing layer being immiscible or less miscible with the slurry for the catalyst layer It is possible to suppress the swelling of the polymer electrolyte membrane due to the permeation of the solvent. Thereby, the slurry for catalyst layers can be stably coated on both surfaces of the polymer electrolyte membrane. In addition, since the swelling of the polymer electrolyte membrane is suppressed, the contraction of the polymer electrolyte membrane due to drying can also be suppressed. Thereby, the occurrence of wrinkles and cracks in the membrane electrode assembly can be prevented.

In the present embodiment, the step of forming the solvent permeation preventing layer and the step of applying the slurry for the catalyst layer may be performed in one step. One step refers to coating of the slurry for catalyst layer while forming the solvent permeation prevention layer.
By simultaneously performing the step of forming the solvent permeation preventing layer and the step of applying the slurry for the catalyst layer in one step, it is possible to reduce the manufacturing time and avoid the inclusion of foreign matter and air bubbles between the steps. This makes it possible to stably manufacture a membrane / electrode assembly having few defective products and no wrinkles or cracks.

  The material of the solvent permeation prevention layer is a material which phase separates when the slurry for the catalyst layer is contained at 25% by mass or more as described above, and further, a solvent having low solubility in water is more preferable. Specifically, the material of the solvent permeation prevention layer is preferably a non-protonic and low polar (dielectric constant) solvent. More specifically, the relative dielectric constant is preferably 25 or less, more preferably 10 or less. In particular, hexane, toluene, chloroform and dichloromethane are preferable. If it is the above-mentioned solvent, the polymer electrolyte can be used not only when the solvent contained in the slurry for the catalyst layer is penetrated into the polymer electrolyte membrane but also when the solvent permeation preventive layer is formed on both sides of the polymer electrolyte membrane. The swelling of the membrane can be suppressed. This makes it possible to stably manufacture a membrane electrode assembly free of wrinkles and cracks.

  The catalyst layer slurry contains an electrolyte, catalyst particles, and a solvent. The electrolyte contained in the slurry for the catalyst layer may be any one having ion conductivity, but in consideration of the adhesion between the catalyst layer and the electrolyte membrane, it is preferable to select a material of the same quality as that of the polymer electrolyte membrane. For example, as the fluorine-based resin, Nafion (manufactured by DuPont Co., Ltd., registered trademark), and as the hydrocarbon-based resin, an engineering plastic or a copolymer of the same into which a sulfonic acid group is introduced can be mentioned.

  The catalyst particles contained in the slurry for the catalyst layer include platinum, palladium, ruthenium, iridium, rhodium and platinum group elements of osmium, iron, lead, copper, chromium, cobalt, nickel, manganese, vanadium, molybdenum, gallium, Metals such as aluminum or alloys thereof, oxides, double oxides, etc. can be used. Among them, platinum and platinum alloys are preferable. In addition, the particle size of these catalysts is preferably 0.5 to 20 nm because the catalyst activity is reduced when the particle size is too large, and the stability of the catalyst is reduced when the particle size is too small. More preferably, 1 to 5 nm is good.

  The catalyst particles may be used alone, and preferably supported on a conductive support. Carbon particles are generally used as the conductive support. The carbon particles may be of any type as long as they are in the form of fine particles and conductive and can not be used as catalysts, but carbon black, graphite, graphite, activated carbon, carbon fibers, carbon nanotubes, fullerenes may be used. it can. If the particle size of the carbon particle is too small, the electron conduction path is difficult to be formed, and if it is too large, the electrode catalyst layer becomes thick and the resistance increases, so that the output characteristics are degraded. preferable. More preferably, it is 10 to 100 nm.

  Although it does not specifically limit as a solvent contained in the slurry for catalyst layers, What can disperse | distribute or melt | dissolve electrolyte is good. Commonly used solvents include water, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, alcohols such as isobutyl alcohol and tert-butyl alcohol, acetone, methyl ethyl ketone and methyl propyl ketone , Methyl butyl ketone, methyl isobutyl ketone, methyl amyl ketone, pentanone, heptanone, cyclohexanone, cyclohexanone, methylcyclohexanone, acetonylacetone, diethyl ketone, diethyl ketone, dipropyl ketone, ketones such as diisobutyl ketone, tetrahydrofuran, tetrahydropyran, dioxane, diethylene glycol Ethers such as dimethylether, anisole, methoxytoluene, diethylether, dipropylether, dibutylether, isopropyl Minamine, butylamine, isobutylamine, cyclohexylamine, diethylamine, amines such as aniline, propyl formate, isobutyl formate, amyl formate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, butyl acetate, isobutyl acetate, pentyl acetate, isopentyl acetate, propionic acid Esters such as methyl, ethyl propionate and butyl propionate, other acetic acid, propionic acid, dimethylformamide, dimethylacetamide, N-methylpyrrolidone and the like may be used. Also, as glycol and glycol ether solvents, ethylene glycol, diethylene glycol, propylene glycol, ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diacetone alcohol, 1-methoxy-2-propanol, 1-ethoxy-2 -Propanol etc. are mentioned.

  Examples of the formation of the solvent permeation preventing layer and the coating method of the catalyst layer slurry include, but are not particularly limited to, doctor blade method, die coating method, dipping method, screen printing method, laminator roll coating method, spray method and the like.

Here, the coating pattern on the polymer electrolyte membrane may be continuous, striped, intermittent, etc., but is not particularly limited. A mask material may be used to apply a predetermined shape.
Examples of the method for drying the catalyst layer slurry include hot air drying, IR (infrared) drying, and reduced pressure drying, but the method is not particularly limited.

First Embodiment
The first embodiment will be described.
In the manufacturing method of the first embodiment, the coating solution for the solvent permeation preventing layer is applied to both surfaces of the polymer electrolyte membrane to form the solvent permeation preventing layer (step S50), and then the solid polymer electrolyte membrane is obtained. The catalyst layer slurry is applied to both surfaces to form a catalyst layer (step S60). Thereafter, the entire structure is dried (step S70). Each coating of the coating liquid for the solvent permeation preventing layer and the slurry for the catalyst layer may be performed on one side or on both sides simultaneously.

Second Embodiment
Next, a second embodiment will be described.
In the second embodiment, the formation of the solvent permeation prevention layer (coating of the coating liquid for the solvent permeation prevention layer) and the coating of the catalyst layer slurry are performed in one step.
As a method of simultaneously performing formation of a solvent permeation prevention layer and application | coating of the slurry for catalyst layers at one process, although following 1st method-3rd method can be illustrated, it does not specifically limit.
In the first method, as shown in FIG. 2, the coating die head 20 for coating the coating liquid for the solvent permeation preventing layer and the coating die head 21 for slurry coating for the catalyst layer are arranged in parallel in the moving direction This is a method of applying the slurry for catalyst layer on the coating solution for the solvent permeation preventing layer coated while coating the coating fluid for the solvent permeation preventing layer with the coating die head 20.
In the second method, as shown in FIG. 3, the coating solution for the solvent permeation preventing layer is applied using the multilayer slit die head 22 capable of applying the coating solution for the solvent permeation preventing layer and the slurry for the catalyst layer. However, it is a method of coating the slurry for catalyst layers on the coating liquid for solvent permeation prevention layers coated.
The third method is, as shown in FIG. 4, a method of applying an ink 15 in which a coating liquid for a solvent permeation prevention layer and a slurry for a catalyst layer are mixed in advance using a multilayer slit die head 22.

(Manufactured membrane electrode assembly)
The membrane electrode assembly 12 according to the present embodiment is, for example, a structure as shown in FIG. 5 as a cross-sectional view. The membrane electrode assembly 12 is manufactured by the above-described manufacturing method, and includes the polymer electrolyte membrane 1 and the air electrode side electrode catalyst layer 2 formed on one surface of the polymer electrolyte membrane 1. And the fuel electrode side electrode catalyst layer 3 formed on the other surface of the polymer electrolyte membrane 1. The fuel electrode side electrode catalyst layer 3, the polymer electrolyte membrane 1, and the air electrode side electrode catalyst layer 2 are laminated in this order.

  FIG. 6 is an exploded cross-sectional view showing a configuration example of a unit cell 11 of a polymer electrolyte fuel cell equipped with the membrane electrode assembly 12. As shown in FIG. 6, the air electrode side gas diffusion layer 4 and the fuel electrode side gas diffusion layer 5 are respectively opposed to the air electrode side electrode catalyst layer 2 and the fuel electrode side electrode catalyst layer 3 of the membrane electrode assembly 12. It is arranged. Thus, the air electrode 6 and the fuel electrode 7 are formed respectively. The air electrode 6 and the fuel electrode 7 are sandwiched by a pair of separators 10 to form a single cell 11. One set of separators 10 is made of an electrically conductive and gas impermeable material, and a gas flow path for reaction gas flow disposed facing the air electrode side gas diffusion layer 4 or the fuel electrode side gas diffusion layer 5 And a cooling water passage 9 for circulating the cooling water disposed on the main surface opposite to the gas passage 8.

  In this single cell 11, an oxidant such as air or oxygen is supplied to the air electrode 6 through the gas passage 8 of one of the separators 10, and a fuel gas containing hydrogen is passed through the gas passage 8 of the other separator 10. Alternatively, the organic fuel is supplied to the fuel electrode 7 to generate power.

(Such as effects)
In the present embodiment, the solvent permeation preventing layer 13 is formed on the solid polymer electrolyte membrane 1, and the catalyst layer slurry 14 is coated on the solvent permeation preventing layer 13 and then dried to manufacture the membrane electrode assembly 12.
According to this manufacturing method, the membrane electrode assembly 12 excellent in the shapes of the polymer electrolyte membrane 1 and the catalyst layers 2 and 3 can be easily manufactured.

The step of forming the solvent permeation prevention layer 13 and the step of applying the slurry 14 for catalyst layer may be simultaneously performed in one step.
With such a manufacturing method, the time between steps is eliminated. As a result, not only the manufacturing time is shortened, but mixing of foreign matter and air bubbles between processes can be avoided, and a membrane electrode assembly 12 with few defective products and no wrinkles and cracks can be manufactured stably.

As the solvent permeation prevention layer 13, a non-protonic solvent having a relative dielectric constant of 25 or less may be used.
If it is such a manufacturing method, it will be suppressed that the solvent of the slurry 14 for catalyst layers in the solid polymer electrolyte membrane 1 because the solvent permeation prevention layer 13 is either of the above-mentioned solvent. Thereby, swelling / shrinkage is suppressed, and a membrane electrode assembly free from wrinkles and cracks can be easily manufactured.
And, by manufacturing the membrane electrode assembly 12 in the present embodiment, the adhesion between the polymer electrolyte membrane 1 and the catalyst layers 2 and 3 is excellent, and the shapes of the polymer electrolyte membrane 1 and the catalyst layers 2 and 3 are excellent. A membrane electrode assembly can be provided.

Next, an embodiment based on the present invention will be described.
[Preparation of slurry for catalyst layer]
Put platinum supported carbon (TEC10E50E, made by Tanaka Kikinzoku Co., Ltd.) in a container, add water and mix, then add 1-propanol and electrolyte (Nafion (registered trademark) dispersion liquid, Wako Pure Chemical Industries) and stir, catalyst layer Slurry was obtained.

Example 1
Hexane is doctor blade coated on the surface of a polymer electrolyte membrane (Nafion 212CS, manufactured by DuPont) to form a solvent permeation preventing layer, and then the above slurry for catalyst layer is coated by a die coating method, and the inside of a furnace at 80 ° C. The membrane electrode assembly of Example 1 was produced by drying with the above.

Example 2 to Example 5
Example 2-Example same as Example 1, except that cyclohexane, toluene, chloroform, dichloromethane, diethyl ether, tetrahydrofuran or pyridine was used as the solvent permeation preventing layer as shown in Table 1. Each membrane electrode assembly of 5 was produced.

[Example 6]
A membrane / electrode assembly of Example 6 was produced in the same manner as Example 1, except that the solvent permeation prevention layer and the catalyst layer slurry were simultaneously coated using a multilayer slit die head.

Comparative Example 1
The above-mentioned slurry for catalyst layer is directly coated on the surface of a polymer electrolyte membrane by a die coating method without forming a solvent permeation prevention layer, and dried in an oven at 80 ° C., thereby bonding the membrane electrode of Comparative Example 1 The body was made.

Comparative Example 2
A membrane / electrode assembly of Comparative Example 2 was produced in the same manner as Example 1, except that ethanol was used as the solvent permeation prevention layer.

The membrane electrode assemblies of Example 1-9 and Comparative Examples 1 and 2 were evaluated for the presence or absence of wrinkles or cracks of 10 μm or more.
The evaluation results are shown in Table 1.

[Evaluation of membrane electrode assembly]
The crack was evaluated by observing with a microscope (magnification: 200 times). The eyelids were checked visually.
As shown in Table 1, when the solvent permeation prevention layer was not formed (Comparative Example 1), the polymer electrolyte membrane swelled, and it was not possible to coat the slurry for catalyst layer. In addition, when acetone is used as a solvent permeation prevention layer, ethanol and a slurry for a catalyst layer are mixed, and the permeation of the solvent into the polymer electrolyte membrane can not be prevented, and the membrane electrode assembly is produced without wrinkles and cracks. I could not do it. On the other hand, in the membrane electrode assembly manufactured in the example, no crack of 10 μm or more was observed. Moreover, it was the membrane electrode assembly excellent in the shape without wrinkles. That is, according to the manufacturing method concerning this embodiment, it was checked that a membrane electrode assembly without wrinkles and a crack can be provided simply.

  As described above, according to the present embodiment, a method of manufacturing a membrane electrode assembly in which the catalyst layer is disposed to face each other on both sides of the polymer electrolyte membrane, is provided on both sides of the polymer electrolyte membrane. A step of forming a solvent permeation preventing layer (Step 50), and a step of applying a catalyst layer slurry on both surfaces of the solid polymer electrolyte membrane on which the solvent permeation preventing layer is formed (Step 60) And drying the catalyst layer slurry and the underlying polymer electrolyte membrane (step 70). Thereby, the membrane electrode assembly 12 excellent in each shape of the polymer electrolyte membrane 1 and the air electrode side electrode catalyst layer 2 and the fuel electrode side electrode catalyst layer 3 can be easily manufactured.

In addition, by simultaneously performing the step of forming the solvent permeation prevention layer and the step of applying the slurry for the catalyst layer, it is possible to reduce the manufacturing time and avoid mixing of foreign matter and air bubbles between the steps. This makes it possible to stably manufacture a membrane / electrode assembly having few defective products and no wrinkles or cracks.
Further, by using any of hexane, toluene, chloroform and dichloromethane as the solvent permeation prevention layer, it is possible not only to prevent the solvent contained in the slurry for catalyst layer from permeating into the polymer electrolyte membrane, but also the solvent permeation prevention layer The swelling of the polymer electrolyte membrane can be suppressed also when forming on both sides of the polymer electrolyte membrane. This makes it possible to stably manufacture a membrane electrode assembly free of wrinkles and cracks.

  The present invention is very suitably applied to, for example, a polymer electrolyte fuel cell.

1 polymer electrolyte membrane 2 air electrode side electrode catalyst layer 3 fuel electrode side electrode catalyst layer 4 air electrode side gas diffusion layer 5 fuel electrode side gas diffusion layer 6 air electrode 7 fuel electrode 8 gas flow passage 9 cooling water flow passage 10 separator 11 Single cell 12 membrane electrode assembly 13 solvent permeation preventing layer 14 slurry for catalyst layer 15 mixed ink of solvent permeation preventing layer and slurry for catalyst layer 20 coating die head 21 coating die head 22 multilayer slit die head

Claims (3)

A manufacturing method of a membrane electrode assembly in which catalyst layers are respectively disposed on both sides of a solid polymer electrolyte membrane,
Forming on the solid polymer electrolyte membrane a solvent permeation preventing layer made of a material that is phase separated when the slurry for the catalyst layer for forming the catalyst layer is contained in an amount of 25% by mass or more;
Applying a slurry for a catalyst layer on the solvent permeation preventing layer;
A drying step of drying a structure obtained by applying the slurry for the solvent permeation prevention layer and the catalyst layer on the polymer electrolyte membrane;
A method of manufacturing a membrane electrode assembly comprising:   The method for producing a membrane / electrode assembly according to claim 1, wherein the step of forming the solvent permeation preventing layer and the step of applying the slurry for a catalyst layer are performed in one step.   The method for producing a membrane electrode assembly according to claim 1 or 2, wherein the solvent permeation preventing layer is a non-protonic solvent having a relative dielectric constant of 25 or less.

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