KR100352562B1 - Fabrication of Membrane-Electrode Assembly for Fuel Cells - Google Patents

Abstract

The present invention provides a method for producing an electrolyte membrane-electrode assembly for a direct methanol fuel cell or a polymer fuel cell using a plasma sputtering method, wherein the ink prepared by mixing a carbon powder and a polymer ionomer solution is coated on both surfaces of an electrolyte membrane to form a carbon-ionomer. After forming the layer, the carbon-ionomer layer-coated electrolyte membrane was mounted in a plasma sputtering reactor to deposit a mono- or multi-component metal catalyst material used as a catalyst for the anode and the cathode to deposit a carbon-ionomer layer of the electrolyte membrane. Forming a catalyst layer thereon, and repeating the carbon-ionomer layer formation and the sputter deposition process of the metal catalyst material to form a multi-layer carbon-ionomer layer and a catalyst layer on both sides of the electrolyte membrane, direct methanol fuel cell or polymer Of electrolyte membrane-electrode assembly for fuel cell It relates to crude methods. By the method of the present invention, it is possible to improve the performance by reducing the mass transfer resistance of the reactants and products at the electrode, and also to increase the fuel cell performance by increasing the catalyst loading per unit area.

Description

Manufacturing method of electrolyte membrane-electrode assembly for fuel cell {Fabrication of Membrane-Electrode Assembly for Fuel Cells}

The electrolyte membrane-electrode assembly of a direct methanol fuel cell is composed of a platinum / ruthenium alloy catalyst supported on a porous carbon support, an anode (anode), a cathode (cathode, a cathode), and a polymer cation exchange membrane. It contains the same electrolyte.

In general, in a direct methanol fuel cell, an aqueous methanol solution as a fuel is supplied to the anode in a liquid or gaseous form, and oxygen or air as an oxidant is supplied to the cathode. In the anode, the electrochemical oxidation of methanol and water produces hydrogen ions, electrons, and carbon dioxide. The hydrogen ions move to the cathode through the solid polymer electrolyte membrane, and the electrons move to the cathode through an external circuit to exchange hydrogen ions with oxygen. Participates in an electrochemical reduction reaction to produce water.

Electrode for direct methanol fuel cell is prepared by coating a mixture of catalyst and polymer electrolyte ionomer solution on water repellent porous carbon paper or carbon fiber.

The performance of the direct methanol fuel cell is determined by the electrochemical reaction activity of the catalysts used, the distribution of the polymer electrolyte in the electrode layer, the total amount of platinum, and the like, in particular by the mass transfer such as diffusion of the reactants into the catalyst layer and the release of reaction products. It depends on the ease of use. In order to maximize the ease of mass transfer, the distribution of catalyst and ionomer should be properly adjusted. In addition, if the removal of the water produced at the cathode is not smooth, the catalyst is submerged in water, causing oxygen or air, which is an oxidant, to not diffuse into the catalyst layer, causing flooding that interferes with the electrode reaction. To prevent this, the electrode should be coated with a Teflon-based water repellent material or the thickness of the catalyst layer should be adjusted to increase the rate of water removal.

As such, in the conventional electrode manufacturing method, a thin carbon coating ink made of a mixture of carbon powder and Teflon on a porous carbon paper or carbon fiber was formed to form a carbon layer, and then a method of coating the catalyst layer thereon was used. As a method of coating the catalyst layer on the carbon layer, a spray coating method, a vacuum filtration method, a screen printing method, a tape casting method, or the like is used. Looking at the previously published electrode manufacturing method is as follows.

In US Patent No. 5,523,177, platinum-ruthenium oxide having a surface area of 70 m 2 / g or more is coated with an ionomer and then coated on a porous gas diffusion electrode to be used as an anode, and as a cathode, platinum black coated with Teflon is applied to a porous gas diffusion electrode. After coating, they were bonded to a solid polymer electrolyte to prepare a polymer electrolyte membrane-electrode assembly. In addition, U.S. Patent No. 5,631,099 sets up a catalyst layer on both sides of the central membrane by various techniques such as ion beam etching and vacuum deposition of the catalyst by installing a fiber reinforced porous middle membrane and a porous outer membrane on both sides. The battery design facilitates through-film connection, through-cell water flow, and thin-film electrode fabrication.

Commonly used catalysts are used by supporting catalyst particles of several nanometers to several tens of nanometers in size on a carbon powder support, and such a preparation method is completed through various processes. In particular, the anode catalyst of a direct methanol fuel cell generally uses an alloy of platinum and ruthenium, and is manufactured in an alloy form at a relatively low temperature without annealing or high temperature sintering using a colloidal method.

However, the conventional electrode manufacturing method takes a long time due to a complicated process, and when a large amount of catalyst, such as a direct methanol fuel cell, is supported by about 1 to 3 mg / cm 2, the thickness of the catalyst layer becomes thick, and thus the reaction solution of methanol solution, The supply is not smooth, there is a problem that the delivery path of the hydrogen ions generated at the anode is not only long, and the discharge of the generated carbon dioxide is not easy.

Meanwhile, conventional techniques for directly depositing a catalytic material on the surface of a polymer electrolyte membrane using plasma sputtering techniques are summarized in the following two methods.

First, a metal catalyst layer having a thickness of 1-1000 nm is formed on both sides of the electrolyte membrane and used as an electrode. This method is a direct bond between the electrolyte and the catalyst, but the physical bond is strong, but when a large amount of catalyst is deposited, the utilization efficiency of the catalyst is reduced.

Second, prior to forming the catalyst thin film layer, the carbon powder and the solid polymer electrolyte ionomer solution were mixed at a weight ratio of 1: 3-1: 2, coated on the solid polymer electrolyte membrane with 0.01-1 mg / cm 2, and then on the carbon layer. It is a method of increasing the dispersion degree of a catalyst by supporting a catalyst by a plasma sputtering deposition method. Here, the carbon powder and the solid polymer electrolyte ionomer maintain the electrical contact between the catalyst particles and the contact between the electrolytes, thereby increasing the utilization of the catalyst. However, this method also reduces the utilization efficiency of the catalyst when a large amount of catalyst is deposited.

As such, the above two plasma deposition methods have a problem in that the electrochemical surface utilization rate of the catalyst is low because the process is completed by one catalyst deposition.

Accordingly, in the present invention, in order to solve the problems of the conventional electrode manufacturing method, to directly increase the activity of the methanol fuel cell electrode, to simultaneously support various catalytic elements, and to increase the surface utilization rate of the catalyst, a plasma sputtering technique is used. The present invention proposes a method of manufacturing an electrolyte membrane-electrode assembly by repeating a deposition process in which a component-based or multi-component catalyst is directly supported on a solid polymer electrolyte.

1 is a block diagram of a plasma sputtering reactor for forming a catalyst layer.

2 shows a catalyst layer deposited on a solid polymer electrolyte membrane.

3 shows a catalyst layer deposited on a reinforced electrolyte membrane using a porous support.

4 is a performance curve of a direct methanol fuel cell.

<Explanation of symbols for the main parts of the drawings>

1: air

2: helium or helium and oxygen

3: valve for maintaining the normal pressure

4,5,10,11,12: valve

6: plasma sputtering reactor

7: high vacuum pump

8: low vacuum pump

9: main valve

13: gas diffusion layer

14: catalyst layer

15: solid polymer electrolyte membrane

16: carbon

17: platinum

18: ionomer

19: reinforced electrolyte membrane

The present invention provides a method for producing an electrolyte membrane-electrode assembly for a direct methanol fuel cell or a polymer fuel cell using a plasma sputtering method, wherein the ink prepared by mixing a carbon powder and a polymer ionomer solution is coated on both surfaces of an electrolyte membrane to form a carbon-ionomer. After forming the layer, the carbon-ionomer layer-coated electrolyte membrane is mounted in a plasma sputtering reactor to deposit a mono- or multi-component metal catalyst material used as a catalyst for an anode and a cathode, thereby depositing a carbon-ionomer layer of the electrolyte membrane. Forming a catalyst layer thereon, and repeating the carbon-ionomer layer formation and the sputter deposition process of the metal catalyst material to form a multi-layer carbon-ionomer layer and a catalyst layer on both sides of the electrolyte membrane, direct methanol fuel cell or polymer Preparation of electrolyte membrane-electrode assembly for fuel cell It's about Joe's method.

In addition, the present invention uses a solid polymer electrolyte membrane or a reinforced electrolyte membrane as a hydrogen ion conductive electrolyte membrane to form a multi-layered carbon-ionomer layer and a catalyst layer on both sides of the electrolyte membrane by the method of claim 1 to form an electrolyte membrane-electrode assembly. The present invention relates to a method for producing a polymer electrolyte fuel cell or a direct methanol fuel cell, the method comprising manufacturing and using the assembly in a fuel cell.

The present invention is characterized in that the carbon-ionomer layer and the catalyst layer are coated with two or more layers to form a multi-layer electrode, thereby improving adhesion between the carbon layer and the catalyst layer, so that a large amount of catalyst is uniformly supported in the carbon layer. .

In addition, according to the present invention, Group 8 metals such as platinum (Pt), ruthenium (Ru), osmium (Os), nickel (Ni), palladium (Pd), iron (Fe), and iridium (Ir) are used alone. Or by depositing a multi-component catalyst thin film made of two or more metals.

In addition, the present invention is to improve the porosity of the catalyst layer to uniformly distribute the electrolyte ionomer on the surface of the carbon layer, to uniformly disperse the catalyst during catalyst deposition, and to facilitate mass transfer of reactants and products during fuel cell reaction. It is characterized by.

In addition, the present invention is characterized by using a reinforced electrolyte membrane prepared by impregnating an electrolyte ionomer in a porous metal sponge instead of a solid polymer electrolyte membrane generally used.

1 is a block diagram of a plasma sputtering reactor for forming a catalyst layer used in the present invention. After the pressure is maintained below 1 mPa using the high vacuum pump 7 and the low vacuum pump 8 to remove and maintain the cleanness of the gases present in the plasma sputtering reactor 6, helium or helium and oxygen gas ( 2) is flowed and maintained at a vacuum pressure of 0.1-1 Pa to form a plasma by using an external direct current or radio frequency power supply device, and a catalyst thin film is formed using this plasma.

To form a multicomponent catalyst thin film, use a single target in the form of an alloy, or use a vacuum reactor in a multi-target system with multiple installations of a single component target, and use oxygen gas to make the catalyst into a metal oxide. Mix and feed with helium gas at a rate of 50% and maintain the temperature of the substrate holder at 80-200 ° C.

In the present invention, as shown in FIG. 2, first, an ink made by mixing carbon 16 and ionomer 18 on one surface of the solid polymer electrolyte membrane 15 is coated to form a carbon-ionomer layer, and then plasma A metal catalyst material 17 (eg platinum) is vacuum deposited in the sputtering reactor to form several nanometers of catalyst layer 14 over the carbon-ionomer layer.

If a large amount of carbon-ionomer layer and catalyst layer are formed in a single process, the distribution of the catalyst and ionomer is not uniform. Therefore, in the present invention, the carbon-ionomer layer coating and the plasma sputter deposition process of the catalyst are repeated. Allow the carbon-ionomer layer + catalyst layer to be formed. On the opposite side of the polymer electrolyte membrane, the multilayer carbon-ionomer layer + catalyst layer is coated through the same process as above to complete the electrolyte membrane-electrode assembly (MEA) in which electrodes are formed on both sides of the electrolyte membrane.

Using the plasma sputtering technique used in the present invention, the average particle size of the catalyst can be controlled to about 10-100 mm 3. Therefore, when the desired amount of catalyst is divided and deposited several times to produce a multi-layer carbon-ionomer layer + catalyst layer, the distribution of the catalyst is uniform, thereby improving the utilization of the catalyst, and physically bonding the carbon-ionomer layer with the catalyst particles. This is also improved, and the ion conductivity and the electrical conductivity of the electrode are improved.

In the electrolyte membrane-electrode assembly manufacturing method of the present invention, the carbon-ionomer layer and the catalyst layer are manufactured by an iterative process rather than being completed in one step. When the sputter deposition of the carbon-ionomer layer and the catalyst layer is repeatedly performed in a small amount, the distribution of the catalyst metal particles deposited on the carbon-ionomer layer is uniform, and the particle size of the catalyst is kept small without increasing.

When the carbon-ionomer layer and the catalyst layer are repeatedly coated about five times, an electrode layer having a thickness of about 10-15 μm is obtained. The multilayer electrode prepared in the present invention has a thicker thickness of the entire electrode layer than the single layer electrode formed on the electrolyte membrane, but has a thickness of 1 / 3-1 compared with the electrode layer of the conventional electrode manufacturing method of forming a catalyst layer on carbon paper or carbon fiber. Very thin, about 10. Therefore, the supply of the reactant hydrogen or methanol aqueous solution and the discharge of the carbon dioxide product are very easy at the anode electrode. In addition, since the electrode layer is thin, the migration path of the hydrogen ions generated by the electrochemical oxidation of the methanol aqueous solution is shortened, thereby directly increasing the performance of the methanol fuel cell. Since the surface of the carbon-ionomer layer is rough and porous, it is easy to disperse the catalyst particles during the plasma deposition process, and forming a multi-layer electrode effectively disperses a large amount of catalyst.

The fuel cell electrode manufactured in the present invention has a structure as shown in FIG. 2. The gas diffusion layer 13 uses porous carbon paper or carbon cloth having a thickness of 0.1-0.5 mm, which is coated with 10-50% by weight of Teflon to have water repellency.

Carbon black or activated carbon is used as the carbon powder, and carbon black having a particle size of 1-100 nm and a surface area of 50-1000 m 2 / g is preferable. The polymer ionomer used in combination with the carbon powder is a hydrogen ion conductive polyperfluorosulfonate-based material, which serves to adhere the carbon layer and serves as a passage for transferring hydrogen ions generated from the electrode. It is used as a solution dissolved in 5-15% by weight in alcohol solvents to form a. Representative examples thereof include Nafion solution (5 wt% Nafion solution, Du Pont) and Flemion solution (9 wt% Flemion solution, Asahi Grass).

When preparing a mixed ink of carbon powder and ionomer, the dispersity of the ionomer varies according to the solvent used, and the pore size of the coated carbon-ionomer layer also varies. In order to mix such carbon powder and ionomer solution, the C2-C8 organic solvent containing an ester group, an ether group, a carboxyl group, a carbonyl group, an amino group, an alcohol group, or a mixture thereof can be used.

In the preparation of the mixed ink of the carbon powder and the ionomer solution, first, the carbon powder is added to an organic solvent such as isopropanol or n-butyl acetate, and then stirred, followed by stirring and mixing while adding a small amount of the ionomer solution. At this time, the mixing ratio of the carbon powder and the ionomer is 1 to 25 on a dry weight basis, and preferably, the ink is mixed by stirring the carbon powder, a 5% Nafion solution, and a solvent at a ratio of 1:20:20 (by weight). Manufacture. The amount of carbon coated on the electrolyte membrane in one coating is about 0.05 to 1.0 mg / cm 2, and the ionomer is suitably 0.01 to 0.5 mg / cm 2 on a dry weight basis.

Methods of coating ink prepared by mixing carbon powder and ionomer solution on an electrolyte membrane include spray coating using an airbrush, screen printing, tape casting, and transfer.

In order to increase the reaction activity of the electrode, it is necessary to increase the utilization of the catalysts present in the electrode, and to do this, it is necessary to improve the contact between the catalyst particles and the ionomer and to increase the pore size of the catalyst layer to reduce the mass transfer resistance of the reactants and the reaction product. In order to form a catalyst layer having such a structure, it is advantageous to use an organic solvent that is somewhat more lipophilic than an organic solvent having a large hydrophilicity such as isopropanol. N-butyl acetate may be used as such a solvent. After dispersing the carbon powder in a large amount of n-butyl acetate and stirring a small amount of ionomer solution in the solution with an ultrasonic stirrer, the ionomer molecules are uniformly dispersed on the surface of the carbon particles. In addition, the carbon layer prepared using the carbon-ionomer ink thus prepared forms a carbon layer having large internal pores and high porosity. Therefore, when the catalyst metal is supported on the carbon-ionomer layer by the plasma sputtering method, the dispersion of the catalyst becomes very uniform, and the prepared electrolyte membrane-electrode assembly shows very high battery performance.

The solid polymer electrolyte membrane used in the present invention is a polyperfluorosulfonate-based material having a thickness of 25-150 μm, and is typically Nafion (Dupont), Aflex (Aciflex, Asahi Chemical Co.), Flemion (Flemion, Asahi Grass, Inc.). The sulfonate group of the polymer constituting the solid polymer electrolyte membrane is preferably substituted with hydrogen ions or sodium ions in the sputtering process for coating the catalyst metal.

As the electrolyte membrane of the present invention, a synthetic electrolyte membrane or a reinforced electrolyte membrane may be used in addition to the above-described membranes. Therefore, in the present invention, a reinforced electrolyte membrane providing a very rough surface can be prepared and used as a substrate, and a carbon-ionomer layer can be coated on both surfaces of the electrolyte membrane to form a catalyst thin film using a plasma sputtering technique.

As a requirement of the support of the reinforcing electrolyte membrane, it is required to maintain the sponge form, be easily oxidized and not electrically conductive, and must not be easily broken due to its strong physical strength. Metals having these characteristics are formed into a sponge to be used as a support for the reinforced electrolyte membrane. Preferably, a metal sponge such as a nickel sponge or aluminum sponge having a thickness of 10 to 3000 µm, a porosity of 30 to 90%, and a pore size of 0.1 to 100 µm may be used. The support of the reinforced electrolyte membrane can not only electrically insulate the unoxidized metal surface by impregnating the Teflon solution and then sintering and water repelling treatment, but also reduce crossover of the aqueous methanol solution. At this time, the Teflon solution is impregnated with 10 to 80% by weight, sintering is suitable for 30 minutes to 2 hours at a temperature of 300-400 ℃. The sintered support is placed in water and boiled again to undergo oxidation and washing of the metal.

The support of the reinforced electrolyte membrane can be adjusted to a desired thickness using a press. Specifically, the reinforced electrolyte membrane may be adjusted to a final thickness of 20 to 300 μm by thermocompression for 1 to 3 minutes at 100 to 200 ° C. at a pressure of 50 to 100 kg / m 2. Subsequently, the reinforcing electrolyte membrane is prepared to prevent pinholes by coating the support sintered with Teflon using an ionomer solution.

3 shows a configuration diagram of an electrolyte membrane-electrode assembly using the reinforced electrolyte membrane 19. The reinforced electrolyte membrane thus prepared provides a very rough surface, which increases the amount of catalyst supported per unit area and facilitates the dispersion of the catalyst material 17. After preparing a solid polymer electrolyte membrane-electrode assembly using a spray coating method of a carbon layer and a multi-step plasma sputtering technique of a catalyst, a fuel cell is constructed by using a water repellent treated carbon paper or carbon fiber as the gas diffusion layer 13.

The following shows an example of measuring a method of manufacturing an electrolyte membrane-electrode assembly for a fuel cell according to the present invention and the performance of the fuel cell thus manufactured, and the present invention is not limited in scope by these examples.

<Example 1>

Nafion 115 (Dupont) solid polymer electrolyte membrane to be used as a substrate was added to 5% aqueous peroxide solution, heated to 80 ° C for 1 hour, washed, and then boiled with ultrapure water for 2 hours. The washed electrolyte membrane was placed in a 2 molar aqueous sodium hydroxide solution, replaced with an electrolyte membrane in the form of sodium cation, and then boiled with ultrapure water for 2 hours. The electrolyte membrane was sufficiently dried in a drying oven. An ink prepared by mixing and stirring carbon powder, 5% Nafion solution, and isopropanol in a ratio of 1:20:20 on the surface of the dried electrolyte membrane was coated with a spray coating method using a spray brush method about 0.5 mg / cm 2.

The electrolyte membrane in which the carbon layer was formed was fixed in the plasma sputtering vacuum reactor and a metal target to be used as a catalyst was mounted thereon, and then the impurities in the reactor were removed by maintaining a vacuum degree of 1 mPa or less. The catalyst thin film was formed on the substrate after adjusting the voltage and the current until a plasma was formed while flowing helium gas and maintaining a vacuum of 1 Pa. At this time, oxygen gas was mixed and supplied with helium gas at a 50% ratio, and the temperature of the substrate holder was maintained at 200 ° C to form a metal oxide catalyst thin film on the substrate. The loading amount of the catalyst was controlled at a fixed current so that the deposited catalyst had a thickness of about 180 nm. In the same manner, a carbon layer and a catalyst layer were formed on the opposite side of the electrolyte membrane to complete the coating once. A platinum-ruthenium alloy target (50:50 molar ratio) was used for anode deposition and a pure platinum target was used for cathode deposition.

After forming the carbon-ionomer layer + catalyst layer five times in this order to prepare an electrode, the mixture was placed in 5 mol of 80 ° C. aqueous sulfuric acid solution for 2 hours, and then washed three times with ultrapure water. The electrolyte membrane / electrode / gas diffusion layer assembly was completed by pressing for 90 seconds at 140 ° C. and 200 atm with carbon paper containing 20% of Teflon on both sides of the prepared electrode-electrolyte membrane assembly.

The prepared electrolyte membrane / electrode / gas diffusion layer assembly was mounted on a battery frame to directly measure the performance of the methanol fuel cell. The anode of the prepared electrode was coated with platinum-ruthenium (50:50 molar ratio) 1.0 mg-Pt / cm 2 based on platinum, and the cathode was coated with pure platinum 1.0 mg-Pt / cm 2. Curve 2 of Figure 4 shows the direct methanol fuel cell performance of the electrode produced by the above method.

<Example 2>

When preparing a carbon-ionomer mixed ink for carbon layer coating, an ink was prepared using n-butyl acetate instead of isopropanol as a solvent to coat the catalyst layer on the surface of the electrolyte membrane. The remaining experimental conditions, repeated coating method, catalyst deposition conditions, fuel cell performance test conditions and the like are the same as in Example 1. The measured fuel cell performance curve is the same as curve 3 of FIG. 4.

<Example 3>

Teflon solution was impregnated into a sponge-shaped porous nickel plate having a thickness of 1.0 mm and sintered at 350 ° C. for 30 minutes in an oxygen atmosphere. At this time, the amount of Teflon was 80% by mass. The sintered support was put in water, boiled again, and pressed in a press to adjust the thickness to 150 μm. A 5% Nafion solution was coated on a nickel sponge to prevent pinholes from occurring, followed by thermocompression bonding at 120 ° C. and 50 kg / m 2 for 1 minute using a press to prepare a reinforced electrolyte membrane.

After preparing a reinforced electrolyte membrane-electrode assembly using multi-step carbon layer formation and plasma sputtering techniques as in Example 1, a fuel cell was constructed using 20% Teflon carbon paper as a gas diffusion electrode. The anode was coated with platinum-ruthenium (50:50 molar ratio) 1.0 mg-Pt / cm 2 on a platinum basis, and the cathode was coated with pure platinum 1.0 mg-Pt / cm 2. Curve 4 of Figure 4 is a methanol fuel cell performance curve of the electrode produced by the above method.

Comparative Example 1

Platinum-ruthenium catalyst (20 wt% based on platinum, Pt-Ru / C, Pt: Ru = 50:50 molar ratio, E-Tek) and 5% Nafion solution supported on carbon in a similar manner as in Example 1 Was prepared by mixing and stirring in an isopropanol solvent at a ratio of 1: 6: 20, and then preparing an ink by spray coating using an airbrush gun to support a catalyst on one side of the solid polymer electrolyte membrane to prepare an anode electrode. At this time, the amount of the supported catalyst was 1.0 mg-Pt / cm 2 based on platinum. Cathode electrodes were also prepared in the same manner as above using a 20 wt% Pt / C catalyst to prepare electrodes loaded with 1.0 mg-Pt / cm 2 of platinum. After the electrolyte-electrode-gas diffusion layer assembly was manufactured in the same manner as in Example 1, the electrolyte-electrode-gas diffusion layer assembly was manufactured, and the performance of the direct methanol fuel cell was measured. Curve 1 of FIG. 4 is a performance curve of the fuel cell manufactured by the above method.

The fuel cell performance curve of FIG. 4 was measured under the following conditions. The anode was loaded with 2 mg / cm 2 platinum / ruthenium catalyst, the methanol concentration as fuel was 2.0 mol / l, and the flow rate was 5 cc / min. The cathode was loaded with 2 mg / cm 2 pure platinum catalyst and oxygen was flowed at a flow rate of 100 cc / min. The battery temperature was 80 ° C. and the electrode area was 25 cm 2.

By using the electrolyte membrane-electrode assembly for direct methanol fuel cell prepared by the present invention, there is no need to carry a catalyst support on a carbon powder support, compared to the conventional electrolyte membrane-electrode assembly manufacturing method, and a fundamental manufacturing process of metal salts used as a precursor. The process is very simple because it is omitted. In addition, when using a multi-component metal as a catalyst it is possible to easily form a catalyst thin film layer by the plasma sputtering method. In addition, since the catalyst thin film layer is directly coated on the electrolyte, the loss of the catalyst is reduced, the contact between the catalyst and the electrolyte is improved, and the physical bonding between the catalyst and the carbon layer is further strengthened due to the repeated coating of the carbon powder and the ionomer solution mixture. In addition, the prepared electrolyte membrane-electrode assembly has a thin catalyst layer, thereby smoothly supplying and discharging reactants and products. In addition, the use of the roughened reinforced electrolyte membrane can increase the amount of catalyst supported per unit area, which is advantageous for miniaturization of a methanol fuel cell.

Claims (13)

In a method of manufacturing an electrolyte membrane-electrode assembly for a direct methanol fuel cell or a polymer fuel cell using a plasma sputtering method, an ink prepared by mixing a carbon powder and a polymer ionomer solution is coated on both surfaces of an electrolyte membrane to form a carbon-ionomer layer. Then, the carbon-ionomer layer-coated electrolyte membrane is mounted in a plasma sputtering reactor to deposit a mono- or multi-component metal catalyst material used as an anode and a cathode, thereby depositing a catalyst layer on the carbon-ionomer layer of the electrolyte membrane. Forming and repeating the carbon-ionomer layer formation and the sputter deposition process of the metal catalyst material to form a multi-layered carbon-ionomer layer and a catalyst layer on both sides of the electrolyte membrane, electrolyte for direct methanol fuel cell or polymer fuel cell Method of manufacturing membrane-electrode assembly. The method of claim 1, wherein the electrolyte membrane is a polyperfluorosulfonate-based solid polymer electrolyte membrane having a thickness of 25 to 150 µm. The method of claim 2, wherein the sulfonate group of the polymer constituting the solid polymer electrolyte membrane is substituted with hydrogen ions or sodium ions. The method of claim 1, wherein the electrolyte membrane is a reinforced electrolyte membrane, the support of the reinforced electrolyte membrane is a metal sponge such as nickel sponge or aluminum sponge having a thickness of 10-3000 µm, porosity 30-90%, pore size 0.1-100 µm, The support is water-treated by impregnating 10 to 80% by weight of the Teflon solution and then sintering at 300 to 400 ° C. for 30 minutes to 2 hours. The method according to claim 4, wherein the reinforced electrolyte membrane is thermocompressed for 1 to 3 minutes at a pressure of 50 to 100 kg / cm 2 at 100 to 200 ° C. using a press to adjust the final thickness to 20 to 300 μm. The method according to claim 2 or 4, wherein in the case of coating the multi-component catalyst on the electrolyte membrane, oxygen gas is used in order to use a single target in an alloy form or to install multiple targets of a single component, and to make the catalyst a metal oxide. A method of mixing with helium gas at a ratio of 5-50%, and maintaining the temperature of the substrate holder at 80-200 ° C. The carbon powder according to claim 2 or 4, wherein the carbon powder is carbon black having a particle size of 1-100 nm and a surface area of 50-1000 m 2 / g, and the polymer ionomer is a hydrogen ion conductive polyperfluorosulfonate-based substance. Using as a solution dissolved 5-15% by weight in a solvent. The method according to claim 2 or 4, wherein the carbon powder and the ionomer solution are mixed with an organic solvent having 2 to 8 carbon atoms including ester group, ether group, carboxyl group, carbonyl group, amino group, alcohol group alone or a mixture thereof. Way to be. The process according to claim 2 or 4, wherein the mixing ratio of the carbon powder and the ionomer is 1-25 on a dry weight basis. The method according to claim 2 or 4, wherein the method of coating the ink prepared by mixing the carbon powder and the ionomer solution on the electrolyte membrane is a spray coating method using an air brush, a screen printing method, a tape casting method, or a transfer method. The method according to claim 2 or 4, wherein the metal catalyst material is a Group 8 metal alone, such as platinum, ruthenium, osmium, nickel, palladium, iron, iridium, or a mixture or alloy of two or more of the metals. The method of claim 2 or 4, wherein the carbon-ionomer layer and the catalyst layer are repeatedly coated five times to obtain an electrode layer having a thickness of about 10-15 μm. Using a solid polymer electrolyte membrane or a reinforced electrolyte membrane according to claim 2 or 4 as a hydrogen ion conductive electrolyte membrane, a multilayer carbon-ionomer layer and a catalyst layer are formed on both surfaces of the electrolyte membrane by the method of claim 1 to form an electrolyte membrane. A method of manufacturing a polymer electrolyte fuel cell or a direct methanol fuel cell, comprising manufacturing an electrode assembly and using the assembly in a fuel cell.