DE102023102497A1 - MEMBRANE-ELECTRODE ARRANGEMENT FOR A FUEL CELL AND METHOD FOR PRODUCING THE SAME - Google Patents

Abstract

The present disclosure relates to a membrane electrode assembly for a fuel cell, and more particularly to a membrane electrode assembly for a fuel cell manufactured using a combination of a direct coating process and a decal process, and to a method for producing the same. For this purpose, a method for producing a membrane-electrode assembly for a fuel cell is provided, the method comprising: a preparation step, in which are independently carried out: an oxidation electrode preparation step S100, in which an oxidation electrode 20 is formed by an electrode slurry is sprayed directly onto an electrolyte membrane 30 by a sprayer 60, and a reduction electrode preparation step S120, in which a reduction electrode 40 is formed by spraying electrode slurry directly onto a release paper 50, a step S140, in which the electrolyte membrane 30 is formed on which the oxidation electrode 20 is applied and the release paper 50 on which the reduction electrode 40 is applied are laminated and the electrolyte membrane 30 and the release paper 50 are transferred by a decal method, a step S160 in which the release paper 50 is separated, and a Step S180, in which a membrane-electrode assembly 10 is completed.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority Korean Patent Application No. 10-2022-0087107 , filed with the Korea Intellectual Property Office on July 14, 2022, the disclosure of which is incorporated herein by reference.

BACKGROUND

Area

The present disclosure relates to a membrane electrode assembly for a fuel cell, and more particularly to a membrane electrode assembly for a fuel cell manufactured using a combination of a direct coating process and a decal process, and a method for producing the same.

Description of the prior art

A fuel cell is a power generation system that converts the energy of a fuel directly into electrical energy through a chemical reaction. For example, the fuel cell obtains electrical energy through a reaction in which water is produced from hydrogen and oxygen, i.e. through an oxidation reaction of hydrogen. Depending on the type of electrolytes used, fuel cells are divided into phosphoric acid fuel cells, molten carbonate fuel cells, solid oxide fuel cells, polymer electrolyte membrane fuel cells, alkaline fuel cells and the like. Fuel cells basically work on the same principle, but differ in terms of the types of fuel used, operating temperatures, catalysts, electrolytes and the like.

Among fuel cells, the polymer electrolyte membrane fuel cell (PEMFC) has very good performance characteristics, low operating temperature and fast start-up and response characteristics compared to other fuel cells. The scope of application of the polymer electrolyte membrane fuel cell is also broad; For example, the polymer electrolyte membrane fuel cell is used as a portable power source for a portable electronic device, a transportable power source such as a power source for a vehicle, or a dispersion generation power source such as an environmentally friendly power generation system for a home or public building.

The polymer electrolyte membrane fuel cell has a membrane electrode assembly (MEA) as a basic component to generate electricity by causing an electrochemical reaction with fuel. The membrane-electrode assembly includes an electrolyte membrane and an oxidation electrode (an anode electrode or fuel electrode) and a reduction electrode (a cathode electrode or air electrode) disposed on two opposing surfaces of the electrolyte membrane. The electrodes typically each contain a catalyst layer and a diffusion layer. The diffusion layer typically consists of a microporous layer and a carrier layer. In general, membrane electrode assemblies are essentially manufactured using two processes.

First, a direct coating process is a process in which an electrolyte membrane (ionic conductor membrane) is coated with an electrode material (electrode slurry) by directly spraying the electrode material with a spray device such as an airbrush. In the direct coating method, if the electrode is thick, the electrode material must be sprayed continuously with ten to twenty nozzles, because it is difficult to form the electrode by spraying the electrode material only once with the nozzle. Therefore, there is a problem that the equipment increases in volume and is expensive. The direct coating process also has the disadvantage that fine holes or cracks arise during the coating and drying process when the layer thickness is large.

Secondly, a decal process is a process in which an electrode layer (an anode and a cathode) is produced by applying an electrode slurry formed by mixing a catalyst, an ionomer and a solvent onto a support body made of a release film such as a decal process Teflon or imide film is applied and the electrode slurry is dried, the electrode layer is aligned with two opposing surfaces of an electrolyte membrane (ion conductor membrane) and then transferred by applying heat and pressure. In the decal process, heat and pressure must be applied simultaneously to produce the membrane-electrode arrangement. The decal process involves hot transfer using a flat plate press or a roller press.

However, the decal process requires the electrode layer (anode and cathode) to be transferred and hot printed sections to be present on the same surface to achieve the Transfer electrode layer by applying force from two opposite sides. With varying electrode size, the thickness varies at different portions, so heat and pressure are not transferred, which may cause the problem that the electrode and electrolyte membrane are not transferred. An anode and a cathode of the same size must therefore be used.

In addition, when the electrode moves in a roll-to-roll system (from an unwinder to a rewinder) in the decal process, a surface of the applied electrode layer comes into contact with a guide roller. After the electrode layer has been applied, a surface of the electrode layer of a web is therefore damaged by contact with the guide roller. Damaging the surface of the electrode layer reduces the performance of the membrane-electrode arrangement.

To produce an oxidation electrode using the decal process, a predetermined or larger amount of ionomers must also be supplied. This is because the transfer does not occur correctly with a small amount of ionomer as the ionomer acts as a binder. However, when increasing the amount of ionomer to perform transfer, the sulfone group (-SO2-) of the ionomer attracts a large amount of water, which may cause the problem of flooding of the device.

In addition, since the oxidation electrode is not transferred correctly when manufacturing the membrane-electrode assembly using only the decal process, high-temperature and high-pressure roller transfer is required throughout to transfer the oxidation electrode. Therefore, there is a problem that even the pores of a reduction electrode may be damaged.

[Prior Art Documents]

[patent documents]

• (Patent Document 1) 1. Korean Patent Laid-Open No. 10-2007-0039369 (METHOD OF MEMBRANE ELECTRODE ASSEMBLY USING TRANSFER PROCESS or “Method for a membrane electrode assembly with a transfer process”)
• (Patent Document 2) 2. Korean Patent No. 10-1758960 (ELECTROLYTE MEMBRANE, METHOD OF MANUFACTURING THE SAME, AND MEMBRANE ELECTRODEASSEMBLYAND FUEL CELL INCLUDING THE SAME or “electrolyte membrane, process for producing the same and membrane-electrode arrangement and fuel cell with the same”)
• (Patent Document 3) 3. Korean Patent No. 10-2238261 (METHOD AND SYSTEM FOR MANUFACTURING MEMBRANE ELECTRODE ASSEMBLY FOR FUEL CELL or “Method and system for producing a membrane-electrode assembly for a fuel cell”)

SUMMARY

The present disclosure was made to solve the above-mentioned problems and has as its object to provide a membrane-electrode assembly for a fuel cell manufactured by a combination of a direct coating process and a decal process, and a method for producing the same.

However, the technical problems to be solved by the present disclosure are not limited to those mentioned above, and for those skilled in the art of the present disclosure, other technical problems not mentioned above will be clearly apparent from the following descriptions.

To solve the above-mentioned object, a method for producing a membrane-electrode assembly for a fuel cell is provided, the method comprising the following: a preparation step in which independently carried out: an oxidation electrode preparation step S100 in which an oxidation electrode 20 is formed by spraying an electrode slurry directly onto an electrolyte membrane 30 by a sprayer 60, and a reduction electrode preparation step S120 in which a reduction electrode 40 is formed by spraying electrode slurry directly onto a release paper 50; a step S140 in which the electrolyte membrane 30 on which the oxidation electrode 20 is applied and the release paper 50 on which the reduction electrode 40 is applied are laminated and the electrolyte membrane 30 and the release paper 50 are transferred by a decal method; a step S160, in which the release paper 50 is separated, and a step S180, in which a membrane-electrode assembly 10 is completed.

In the oxidation electrode preparation step S100, the spraying device 60 may spray the electrode slurry to form an oxidation electrode 20 having a first thickness and an oxidation electrode 20 having a two thickness th thickness, which is greater than the first thickness, is formed on a portion.

In addition, the oxidation electrode 20 having the second thickness may include: a first local electrode 22 formed on a side where hydrogen is introduced; and a second local electrode 24 formed on a side where oxygen is introduced, the side opposite to the first local electrode 22.

Furthermore, the first thickness can be 5 to 10 μm and the second thickness can be 11 to 20 μm.

Furthermore, the amount of ionomers used for electrode bonding in the oxidation electrode preparation step S100 may be smaller than the amount of ionomers used for electrode bonding in the reduction electrode preparation step S120.

Furthermore, a low temperature may be in the range of 100 to 120°C, and a low pressure is in the range of 20 to 50 kgf/cm ² .

A thickness of the electrolyte membrane 30 can also be 5 to 20 μm.

To achieve the above-mentioned object, a membrane-electrode arrangement for a fuel cell is provided, the membrane-electrode arrangement having the following: an oxidation electrode 20; an electrolyte membrane 30 and a reduction electrode 40, the electrolyte membrane 30 having a thickness in the range of 5 to 20 μm, the oxidation electrode 20 having a thickness of 5 to 10 μm, the oxidation electrode 20 being formed on a surface of the electrolyte membrane 30 by a direct coating method is, wherein the oxidation electrode 20 comprises: a first local electrode 22 having a thickness in the range of 11 to 20 μm, which is formed on a side where hydrogen is introduced; and a second local electrode 24 having a thickness in the range of 11 to 20 μm, which is formed on a side on which oxygen is introduced, the side opposite to the first local electrode 22, and the oxidation electrode has a thickness in the range of 5 to 20 μm, wherein the reduction electrode 40 is formed on the other surface of the electrolyte membrane 30 by a decal process, and wherein the decal process is carried out at a low temperature in the range of 100 to 120 ° C and a low pressure in the range of 20 to 50 kgf/cm ² is carried out.

According to the embodiment of the present disclosure, the oxidation electrode can be formed by the direct coating so that its thickness is about 1/2 to 1/10 times smaller than a thickness of the reduction electrode. Furthermore, the reduction electrode can be connected in sufficient thickness by using the decal method.

In addition, the oxidation electrode is applied directly to the electrolyte membrane so that the organic solvents contained in the electrode slurry dissolve a surface of the electrolyte membrane. An interfacial bonding force between the electrolyte membrane and the oxidation electrode can therefore be greatly increased compared to the decal method.

In addition, when the oxidation electrode is applied directly to the electrolyte membrane, the direct coating varies depending on the position, so that the thickness can vary and the durability of the oxidation electrode can be improved. Particularly, in an area where hydrogen and oxygen distributors are located, the oxidation electrode has a large thickness so that it can be used for a long period of time without being separated or lost.

Since the oxidation electrode is applied directly, the amount of ionomers used can be minimized compared to the decal process. This very effectively solves the problem of flooding of the membrane-electrode assembly.

In addition, since a sufficient amount of ionomers is used for the reduction electrode, an improvement in the performance of the fuel cell can be expected. The reason for this is that the amount of ionomers on the reduction electrode is less likely to be affected by flooding compared to the oxidation electrode.

In addition, in the decal process of transfer step S140, the reduction electrode is transferred to the electrolyte membrane at low temperature and pressure, so that high porosity of the reduction electrode can be maintained, the pore size can be increased, and the electrochemical performance can be improved. Furthermore, since the decal process of the transfer step S140 is performed at low pressure and low temperature, the thickness of the electrolyte membrane can be maintained and the durability of the membrane-electrode assembly can be improved.

However, the effects that can be achieved with the present disclosure are not limited to those mentioned above, and those skilled in the art can also see other effects not mentioned above from the following description.

BRIEF DESCRIPTION OF DRAWINGS

• 1 ist eine vergrößerte Querschnittsansicht einer Membran-Elektroden-Anordnung für eine Brennstoffzelle gemäß einer Ausführungsform der vorliegenden Offenbarung;
• 2 ist ein Prozessdiagramm, das schematisch ein Verfahren zur Herstellung der in 1 dargestellten Membran-Elektroden-Anordnung für eine Brennstoffzelle zeigt; und
• 3 ist ein Flussdiagramm, das schematisch das Verfahren zur Herstellung der in 1 dargestellten Membran-Elektroden-Anordnung für eine Brennstoffzelle zeigt.

The following drawings accompanying this specification illustrate exemplary embodiments of the present disclosure and, together with the following detailed description, serve to better understand the technical spirit of the present disclosure. This is not to be construed as being limited to the elements shown in the drawings.

• 1 is an enlarged cross-sectional view of a membrane electrode assembly for a fuel cell according to an embodiment of the present disclosure;
• 2 is a process diagram that schematically shows a process for producing the in 1 shown membrane-electrode arrangement for a fuel cell; and
• 3 is a flowchart schematically showing the process for producing the in 1 shown membrane electrode arrangement for a fuel cell.

DETAILED DESCRIPTION OF THE EMBODIMENT

Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the accompanying drawings so that those skilled in the technical field of the present disclosure can easily carry out the embodiment. However, since the description of the present disclosure is only one embodiment for structural and functional description, the scope of the present disclosure should not be construed as being limited to the embodiment described in the present application. Therefore, since the embodiment may be varied in various ways and take various forms, the scope of the present disclosure is to be understood to include equivalents for realizing the technical idea. Furthermore, the fact that a particular object or effect is suggested in the present disclosure does not mean that the specific embodiment must have all effects or such effect. The scope of the present disclosure should therefore not be construed as being limited to this subject matter or effect.

The meaning of the terms described in the present disclosure is to be understood as follows.

Terms such as “first” and “second” are used to distinguish one component from other components, but these terms do not limit the scope of protection. For example, a first component can be referred to as a second component or the second component can also be referred to as a first component. When a component is described as being “connected” to another component, this is to be understood to mean that the component may be directly connected to another component or there may be an intermediate component between the two. When a component is described as being “directly connected” to another component, this should be understood to mean that there is no intermediate component between the components. Other expressions such as “between” or “just between” or “adjacent to” and “immediately adjacent to” which describe a relationship between components should be construed in a similar manner.

Expressions in the singular are to be understood to include those in the plural, unless clearly described in the context as having different meanings. The expressions “comprises”, “comprising”, “has”, “having”, “containing”, “has”, “with” or variations thereof are to be understood inclusively and thus indicate the presence of the mentioned features, integers, steps , operations, elements, components and/or combinations thereof, but does not exclude that one or more other features, integers, steps, operations, elements, components and/or combinations thereof may also be present or added.

Unless otherwise defined, all terms used herein may have the meaning generally understood by those skilled in the art of the present disclosure. Terms, such as those defined in commonly used dictionaries, are to be understood so that their meanings are consistent with meanings in the context of related technologies and are not to be understood in ideal or overly formalized meanings unless expressly so defined in the present disclosure .

EMBODIMENT CONFIGURATION

Below, a configuration of an exemplary embodiment will be described in detail with reference to the accompanying drawings. 1 is an enlarged cross-sectional view of a membrane electrode assembly for a fuel cell according to an embodiment of the present disclosure. As in 1 shown, a membrane-electrode arrangement 10 essentially comprises an oxidation electrode 20, an electrolyte membrane 30 and a reduction electrode 40.

Hydrogen ions and electrons are generated at the oxidation electrode 20 during an oxidation reaction of the fuel. The hydrogen ions migrate through the electrolyte membrane 30 to the reduction electrode 40. The oxidation electrode (the anode electrode or fuel electrode) 20 is formed on an upper surface of the electrolyte membrane 30 by a direct coating method and has a thickness in the range of 5 to 10 μm. The oxidation electrode 20 includes: a first local electrode 22 having a larger thickness in the range of 11 to 20 μm, which is disposed on a side where hydrogen is introduced; and a second local electrode 24 having a larger thickness in the range of 11 to 20 μm, which is disposed on a side where oxygen is introduced, the side opposite to the first local electrode 22.

The first and second local electrodes 22 and 24 may be deposited thicker (a difference in loading) than the oxidation electrode 20 if a spray device 60 moves back and forth several times while spraying a material or sprays a larger amount of material. The first and second local electrodes 22 and 24 improve durability and reliability by preventing separation or loss of the oxidation electrode 20 due to hydrogen and oxygen flow rates.

In comparison with other reaction areas, there is a further problem such as the loss of a catalyst, since different pressures and reactivities occur at an inlet and an outlet for a reactant gas in a reaction area of the membrane-electrode arrangement 10. On the other hand, with the first and second electrodes 22 and 24 according to the present disclosure, such problems can be solved.

In addition, since the oxidation electrode 20 is applied directly to the electrolyte membrane 30, the organic solvents contained in the electrode slurry irregularly dissolve a surface of the electrolyte membrane 30. The interfacial bonding force between the electrolyte membrane 30 and the oxidation electrode 20 can therefore be greatly increased compared to the decal method.

Water is also formed at the reduction electrode (the cathode or air electrode) 40 through a reaction between hydrogen ions and electrons transferred through the electrolyte membrane 30 and oxygen, which is an oxidant. The reaction moves the electrons in an external circuit. The reduction electrode 40 is formed on a lower surface of the electrolyte membrane 30 by the decal method. The decal process is carried out at low temperature in the range of 100 to 120°C and low pressure in the range of 20 to 50 kgf/cm ² .

The reduction electrode 40 is not correctly transferred to a release paper 50 when the temperature is below 100°C. At a temperature of more than 120°C, there is a risk of structural degeneration of the polymer of the electrolyte membrane 30. When the transfer pressure is less than 20 kgf/cm ² , the electrolyte membrane 30 is hardly transferred to the release paper 50. When the transfer pressure is more than 50 kgf/cm ² , the oxidation electrode 20 and the reduction electrode 40 are damaged and the number of pores decreases. For comparison, in the general decal process, the transfer temperature is 120 to 150 °C and the transfer pressure is 100 to 200 kgf/cm ² .

A thickness of the electrolyte membrane 30 can also be 5 to 20 μm. As the thickness decreases, a membrane-electrode arrangement 10 with high performance is realized. If the thickness is less than 5 μm, the electrolyte membrane 30 is easily damaged. If the thickness is more than 20 μm, the performance of the membrane-electrode arrangement 10 is reduced.

Ionomers are used to form the oxidation electrode 20 or the reduction electrode 40. The ionomer serves as a binder, providing a passage through which ions formed by a reaction between a catalyst and a fuel such as hydrogen or methanol travel to the electrolyte membrane. In particular, as the polymer ionomer, sulfonated polytetrafluoroethylene ionomer or sulfonated polymer such as sulfonated polytrifluorostyrene can be used.

In the oxidation electrode 20, the proportion of ionomer used can be a minimum amount of 20 to 50 parts by weight, based on 100 parts by weight, the total amount of carbon and catalyst. If ionomer is used in an amount less than 20 parts by weight, problems may arise because a proper ion transfer passage is not formed in a catalyst layer and ions generated by the catalyst reaction do not move freely can. On the other hand, if the amount exceeds 50 parts by weight, the ionomer covers the catalyst layer, which may cause a problem that the reaction between the catalyst and the fuel cannot be easily carried out. The preferred minimum amount may be 30 to 40 parts by weight.

In the oxidation electrode 40, the proportion of ionomer used may be a minimum amount of 40 to 80 parts by weight, based on 100 parts by weight constituting the total amount of carbon and catalyst. Alternatively, a sufficient amount of 80 parts by weight or more may be used.

The ionomer is a polymer prepared by bridging a copolymer of ethylene and acrylic acid or methacrylic acid with metal ions (Ca ²⁺ , Ba ²⁺ , Zn ²⁺ and the like). A reaction product of a monomer containing phthalazinone and a phenol group and at least one sulfonated aromatic compound can be used, that is, a copolymer of sulfonated poly(phthalazinone ether ketone), sulfonated poly(phthalazinone or sulfone), sulfonated aromatic polymer compound, tetrafluoroethylene and fluorovinyl ether .

HOW THE EMBODIMENT FUNCTIONS

The operation of an exemplary embodiment will be described in detail below with reference to the accompanying drawings. 2 is a process diagram that schematically shows a process for producing the in 1 shown membrane-electrode arrangement for a fuel cell, and 3 is a flowchart schematically showing the process for producing the in 1 shown membrane electrode arrangement for a fuel cell.

Like in the 2 and 3 shown, in the method, an oxidation electrode preparation step S100 is first independently carried out, in which an oxidation electrode 20 is formed by spraying an electrode slurry directly onto the electrolyte membrane 30 by the spray device 60, and a reduction electrode preparation step S120 is carried out, in which the reduction electrode 40 is sprayed directly onto the release paper 50. The oxidation electrode preparation step S100 and the reduction electrode preparation step S120 may be performed sequentially, with either the oxidation electrode preparation step S100 or the reduction electrode preparation step S120 being performed first.

Alternatively, the oxidation electrode preparation step S100 and the reduction electrode preparation step S120 may be performed independently of each other.

Subsequently, the electrolyte membrane 30 on which the oxidation electrode 20 is applied and the release paper 50 on which the reduction electrode 40 is transferred are laminated and transferred by the decal method (S140). The decal process of the transfer step S140 is carried out in the temperature range of 100 to 120°C and in the pressure range of 20 to 50 kgf/cm ² .

The release paper 50 is then separated (S160), so that the membrane-electrode arrangement 10 is completed (S180).

The detailed description of the exemplary embodiments of the present disclosure as described above is intended to enable those skilled in the art to implement and practice the present disclosure. Although the present disclosure has been described above with reference to the exemplary embodiments, it will be understood by those skilled in the art that the present disclosure can be modified and changed in various ways without departing from the scope of the present disclosure. For example, those skilled in the art may use the components disclosed in the above embodiments as a combination of the components. The present disclosure is therefore not limited to the embodiments disclosed herein, but is intended to provide the widest possible scope consistent with the principles and novel features disclosed herein.

The present disclosure may be presented in other specific forms without departing from the spirit and essential features of the present disclosure. The detailed description is therefore to be understood in all senses as illustrative and not restrictive. The scope of the present disclosure should be determined based on a reasonable interpretation of the appended claims, and all changes within the equivalent scope of the present disclosure are within the scope of the present disclosure. The present disclosure is not limited to the embodiments disclosed herein, but is intended to provide the widest possible scope consistent with the principles and novel features disclosed herein. Additionally, the embodiments may be configured or new claims added after the application is filed by combining claims that do not have an expressly stated relationship.

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• KR 1020220087107 [0001]
• KR 1020070039369 [0011]
• KR 101758960 [0011]
• KR 102238261 [0011]

Claims (5)

A method for producing a membrane-electrode assembly for a fuel cell, the method comprising: a preparation step in which are independently carried out: an oxidation electrode preparation step (S100) in which an oxidation electrode (20) with a first thickness is formed and an oxidation electrode (20) having a second thickness larger than the first thickness is formed at a portion by spraying an electrode slurry directly onto an electrolyte membrane (30) by a spraying device (60), and a reduction electrode preparation step ( S120), in which a reduction electrode (40) is sprayed directly onto a release paper (50); a step (S140) in which the electrolyte membrane (30) on which the oxidation electrode (20) is applied and the release paper (50) on which the reduction electrode (40) is applied are laminated and the electrolyte membrane (30) and the release paper (50) is transferred by a decal process; a step (S160) of separating the release paper (50); and a step (S180) of completing a membrane-electrode assembly (10), the first thickness being 5 to 10 µm, the second thickness being 11 to 20 µm, wherein the decal method of the transfer step (S140 ) is carried out in a temperature range of 100 to 120 ° C and a pressure range of 20 to 50 kgf / cm ² . Procedure according to Claim 1 , wherein the oxidation electrode (20) having the second thickness comprises: a first local electrode (22) formed on a side on which hydrogen is introduced; and a second local electrode (24) formed on a side on which oxygen is introduced, the side opposite to the first local electrode (22). Procedure according to Claim 1 , wherein the amount of ionomers used for electrode bonding in the oxidation electrode preparation step (S100) is smaller than the amount of ionomers used for electrode bonding in the reduction electrode preparation step (S120). Procedure according to Claim 1 , wherein a thickness of the electrolyte membrane (30) is 5 to 20 μm. Membrane electrode assembly for a fuel cell, the membrane electrode assembly comprising: an oxidation electrode (20); an electrolyte membrane (30) and a reduction electrode (40), the electrolyte membrane (30) having a thickness in the range of 5 to 20 µm, the oxidation electrode (20) having a thickness of 5 to 10 µm and by a direct coating process on a surface the electrolyte membrane (30), wherein the oxidation electrode (20) comprises: a first local electrode (22) having a thickness in the range of 11 to 20 µm, which is formed on a side to which hydrogen is introduced; and a second local electrode (24) having a thickness in the range of 11 to 20 µm formed on a side to which oxygen is introduced, the side opposite to the first local electrode (22), the reduction electrode (40) is formed by direct spraying on a release paper (50) and then formed on the other surface of the electrolyte membrane (30) by a decal process, and wherein the decal process is carried out at a low temperature in the range of 100 to 120 ° C and a low pressure in the range of 20 to 50 kgf/cm ² is carried out.

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