JP5206074B2 - Membrane / electrode assembly for fuel cell and manufacturing method thereof - Google Patents

Description

  The present invention relates to a membrane / electrode assembly for a fuel cell and a method for producing the same.

  Among fuel cell membrane / electrode assemblies (hereinafter sometimes simply referred to as “membrane / electrode assemblies”) constituting a fuel cell, catalyst layers are disposed on both principal surfaces of the electrolyte membrane (ie, The catalyst layer / electrolyte membrane / catalyst layer structure) is referred to as a three-layer MEA, and further, electrode substrates are disposed on both principal surface sides of the three-layer MEA (that is, an electrode substrate). Material / catalyst layer / electrolyte membrane / catalyst layer / electrode substrate layer structure) is referred to as a 5-layer MEA.

Optimization of the structure of these membrane / electrode assemblies is the key to improving the performance of fuel cells. In the manufacturing process of the membrane / electrode assembly, for example, the following methods (1) to (3) are employed.
(1) A method of forming a catalyst layer on an electrode substrate, also called a gas diffusion layer (GDL), by coating (2) A decal method (a method of transferring a catalyst layer formed on a film to an electrolyte membrane)
(3) Method of directly applying catalyst-containing paste to the electrolyte membrane

  In the method (1), since a catalyst-containing paste containing a catalyst and an electrolyte binder is applied to the porous GDL, waste of the catalyst due to the penetration of the catalyst into the GDL, a decrease in the gas permeability of the GDL, and the like There is a problem.

In the method (2), after each catalyst layer is formed on two films having stable shapes by coating, each catalyst layer is transferred to the electrolyte membrane by hot pressing, so that there is no penetration of the catalyst into the GDL. A catalyst layer having a good dispersion state of the catalyst and the electrolyte binder and a homogeneous pore structure can be formed. However, since the catalyst layer formed on each film is transferred to the electrolyte membrane and then the film must be peeled off from each catalyst layer, the number of steps is large. Further, there is an optimum catalyst / electrolyte binder blending ratio from the viewpoint of ensuring high performance, but the value does not match the optimum catalyst / electrolyte binder blending ratio from the viewpoint of improving transferability and yield during mass production. For this reason, if priority is given to securing high performance, improvement in transferability and yield during mass production must be sacrificed. If priority is given to improvement in transferability and yield during mass production, high performance is sacrificed. Will be. Further, in the method (2), a catalyst layer of a direct methanol fuel cell (DMFC) which is a kind of a polymer electrolyte fuel cell, particularly an anode catalyst layer having a large amount of supported catalyst of about 3 to 6 mg / cm ^2. In the case of forming the catalyst, there is a problem that the catalyst is easily lost during the transfer.

  In the method (3), since the catalyst-containing paste is directly applied to both surfaces of the electrolyte membrane, the number of steps can be reduced as compared with other methods. However, when a perfluorosulfonic acid type electrolyte membrane such as a Nafion (registered trademark) membrane generally used as an electrolyte membrane is used, the electrolyte membrane swells significantly due to the solvent in the catalyst-containing paste, and a good electrolyte There is a problem that a membrane-electrode assembly provided with a membrane cannot be obtained.

  Further, Patent Documents 1 to 4 disclose other methods for producing a membrane / electrode assembly.

In the manufacturing process of the membrane / electrode assembly described in Patent Document 1, a three-layer MEA is formed as follows.
1) The electrolyte membrane is supported on a first temporary substrate having a stable dimension.
2) The electrocatalyst coating composition is directly applied to the surface (first surface) opposite to the surface on the first temporary substrate side of the electrolyte membrane to form the first catalyst layer.
3) A second temporary substrate having a stable dimension is disposed on the first catalyst layer, and the electrolyte membrane is supported from the surface side on which the first catalyst layer is formed.
4) The first temporary substrate is peeled from the electrolyte membrane.
5) The electrocatalyst coating composition is directly applied to the surface (second surface) of the electrolyte membrane exposed by the peeling of the first temporary substrate side to form the second catalyst layer.

In the manufacturing process of the membrane / electrode assembly described in Patent Document 2, a three-layer MEA is formed as follows.
1) A first catalyst layer is formed on a temporary substrate having a stable dimension by printing.
2) Apply the electrolyte film forming liquid to the surface of the temporary substrate on which the first catalyst layer is formed and the first catalyst layer, and dry the applied electrolyte film forming liquid. Thus, an electrolyte membrane is formed.
3) A second catalyst layer is formed on the electrolyte membrane by printing.

  In Patent Document 3, two laminates in which a catalyst layer and an electrolyte membrane are formed in this order on a support are prepared, and the laminate is bonded so that the electrolyte membranes face each other. To peel off.

In Patent Document 4, a cathode catalyst layer is first formed on a support. On the other hand, an electrolyte membrane is formed on silicon oil. A support on which the cathode catalyst layer is formed is stacked on the electrolyte membrane so that the cathode catalyst layer is in contact with the electrolyte membrane, and these are heated to join the cathode catalyst layer and the electrolyte membrane. Next, an anode catalyst layer is formed by screen printing on the opposite side of the surface of the electrolyte membrane joined to the cathode catalyst layer.
JP-T-2006-507623 JP 2005-507150 gazette JP 2000-285932 A JP 2002-280014 A

  In the method described in Patent Document 1, there is a gap between the periphery of the portion of the surface facing the electrolyte membrane of the second temporary substrate that is in contact with the first catalyst layer and the first surface of the electrolyte membrane. Since the second catalyst layer is formed by directly applying the electrocatalyst coating composition to the second surface of the electrolyte membrane, a portion in the vicinity of the void (around the first catalyst layer) of the electrolyte membrane swells. there is a possibility.

  In the method described in Patent Document 2, since the electrolyte membrane solution is applied onto the catalyst layer, the electrolyte membrane solution penetrates into the catalyst layer, and the interface where the three phases of the catalyst, the electrolyte, and the gas are in contact with each other (so-called three phases). (Interface) is reduced, and gas diffusibility is reduced.

  In the method described in Patent Document 3, it is not easy to bond the electrolyte membranes together without causing uneven lamination. If the stacking unevenness occurs, the proton conduction path may be blocked. Here, stacking unevenness means that air bubbles are mixed when the laminates are bonded together, resulting in a portion where the electrolyte membranes are not in contact with each other, or unevenness in the electrolyte membrane due to minute unevenness of the roller jig. is there.

  In the method described in Patent Document 4, similar to the method described in Patent Document 1, the periphery of the portion of the surface of the support that is in contact with the first catalyst layer and the surface facing the support of the electrolyte membrane are formed. An anode catalyst layer is formed by printing on the surface opposite to the above surface of the electrolyte membrane in a state where there are voids therebetween. Therefore, there is a possibility that a portion in the vicinity of the gap (around the first catalyst layer) in the electrolyte membrane swells. Further, silicon oil adhering to the electrolyte membrane may become a resistance component.

  The present invention provides a membrane / electrode assembly for a fuel cell and a method for producing the same that can easily form a catalyst layer while suppressing swelling of the electrolyte membrane.

The method for producing a fuel cell membrane / electrode assembly of the present invention comprises:
Applying a first catalyst-containing paste to a support substrate, drying the applied first catalyst-containing paste, and forming a first catalyst layer;
The first electrolyte layer is embedded in the electrolyte membrane, and the electrolyte membrane is formed so that no voids are formed between the electrolyte membrane and the laminate including the support base and the first catalyst layer. A step of thermocompression bonding to the laminate, and bonding the electrolyte membrane and the first catalyst layer;
Applying a second catalyst-containing paste to the opposite surface of the electrolyte membrane on the side of the support substrate, and drying the applied second catalyst-containing paste to form a second catalyst layer;
Peeling the support substrate from the first catalyst layer.

The fuel cell membrane / electrode assembly of the present invention is a fuel cell membrane / electrode assembly formed by the method for producing a fuel cell membrane / electrode assembly of the present invention,
The electrolyte membrane;
The second catalyst layer disposed in contact with one main plane of the electrolyte membrane;
The first catalyst layer embedded in the electrolyte membrane from the opposite side of the electrolyte membrane to the second catalyst layer side,
A surface opposite to the one main plane of the electrolyte membrane and a surface opposite to the surface of the first catalyst layer facing the second catalyst layer are substantially in the same plane.

  ADVANTAGE OF THE INVENTION According to this invention, the membrane-electrode assembly for fuel cells and its manufacturing method which can form a catalyst layer easily can be provided, suppressing swelling of an electrolyte membrane.

  FIG. 1 is a schematic cross-sectional view of an example of a five-layer MEA produced by the method for producing a membrane / electrode assembly for a fuel cell of the present invention, and FIG. 2 is a diagram showing 3 constituting the five-layer MEA shown in FIG. It is a schematic cross section of layer MEA. An example of the membrane / electrode assembly of the present invention described with reference to FIG. 1 is a five-layer MEA, but the membrane / electrode assembly of the present invention also includes a three-layer MEA.

  As shown in FIGS. 1 and 2, a fuel electrode 6 including a second catalyst layer 4 ′ and a second electrode substrate 5 is disposed on one main plane 1 a of the electrolyte membrane 1. The first catalyst layer 4 of the air electrode 8 composed of the first catalyst layer 4 and the first electrode substrate 7 is embedded in the electrolyte membrane 1 from the side opposite to the second catalyst layer 4 ′ side of the electrolyte membrane 1. The opposite surface 1b of the one main plane 1a of the electrolyte membrane 1 and the opposite surface 4b of the surface 4a of the first catalyst layer 4 facing the second catalyst layer 4 ′ are in the same plane. By arranging a separator with a rib and a current collector plate (not shown) in this order on both main surface sides of a laminate (5-layer MEA) composed of the electrolyte membrane 1, the fuel electrode 6 and the air electrode 8, A single cell (fuel cell) is configured. Protons flow from the fuel electrode 6 through the electrolyte membrane 1 to the air electrode 8. Further, electrons flow from the fuel electrode 6 to the air electrode 8 through an external circuit. As a result, electricity flows between the fuel electrode 6 and the air electrode 8.

  Next, a method for manufacturing the 5-layer MEA shown in FIG. 1 will be described with reference to FIG.

  As shown in FIG. 3A and FIG. 3B, first, a support base material 2 is prepared, a first catalyst-containing paste is applied to one main surface of the support base material 2, and then applied to the support base material 2. The first catalyst-containing paste is dried to obtain the first catalyst layer 4.

  Next, as shown in FIG. 3C, the electrolyte membrane 1 is thermocompression bonded to the laminate 10 made of the first catalyst layer 4 and the support base 2. The first catalyst layer 4 is embedded in the electrolyte membrane 1, the laminate 10 and the electrolyte membrane 1 are in close contact with each other without generating a void, and the electrolyte membrane 1 and the first catalyst layer 4 are joined by heat. . When the support base material 2 is a long belt-like sheet and a plurality of first catalyst layers 4 are formed on one main surface of the support base material 2 at predetermined intervals, the space between the adjacent first catalyst layers 4 is between The electrolyte membrane 1 is adhered to the laminate 10 so as to be filled with a part of the electrolyte membrane 1.

  Next, as shown in FIG. 3D, the second catalyst-containing paste is applied to the surface opposite to the surface of the electrolyte membrane 1 on the support base 2 side, and the applied second catalyst-containing paste is dried. Then, the second catalyst layer 4 ′ is formed. Subsequently, if the support base material 2 is peeled from the first catalyst layer 4, a three-layer MEA is obtained. Next, the first electrode base material 7 and the second electrode base material 5 are bonded to both main surface sides of the three-layer MEA by a known method, whereby a five-layer MEA is obtained.

  In the method for producing a membrane / electrode assembly according to the present invention, the electrolyte membrane 1 having good followability is thermocompression bonded to the laminate 10, so that the two are brought into close contact with each other without generating a gap between the laminate 10 and the electrolyte membrane 1. Can do. Therefore, it is possible to suppress swelling of the electrolyte membrane that may occur due to the presence of voids between the electrolyte membrane 1 and the support base 2 when forming the second catalyst layer 4 ′.

  Both the first catalyst layer 4 and the second catalyst layer 4 ′ contain carbon particles carrying catalyst particles (catalyst-carrying carbon particles) and a hydrogen ion conductive polymer electrolyte. Examples of the catalyst particles include platinum and platinum compounds. Examples of the platinum compound include an alloy of platinum and at least one metal selected from the group consisting of ruthenium, palladium, nickel, molybdenum, iridium, iron, cobalt, and the like.

  Examples of the hydrogen ion conductive polymer electrolyte include perfluorosulfonic acid-based fluorine ion exchange resins. The mixing ratio of the catalyst-supporting carbon particles and the hydrogen ion conductive polymer electrolyte is preferably 1: 0.1 to 1: 1 by weight ratio of the solid content, and is preferably 1: 0.2 to 1: 0.5. More preferably.

  For the formation of the first catalyst layer 4 and the second catalyst layer 4 ′, a catalyst-containing paste obtained by mixing and dispersing the catalyst-supporting carbon particles and the hydrogen ion conductive polymer electrolyte in an appropriate solvent is used. .

  Examples of the solvent include various alcohols, various ethers, various dialkyl sulfoxides, water, or a mixture thereof.

  The method for applying the catalyst-containing paste is not particularly limited. For example, a general method such as knife coater, bar coater, spray, dip coater, spin coater, roll coater, die coater, curtain coater, screen printing, etc. The method can be applied.

  When the membrane / electrode assembly is for a polymer electrolyte fuel cell (PEFC), the thickness of the first catalyst layer 4 and the second catalyst layer 4 ′ is usually preferably 10 to 50 μm, and preferably 15 to 15 μm. More preferably, it is 30 μm. When the membrane / electrode assembly is for a direct fuel cell (DMFC), the first catalyst layer 4 is a cathode catalyst layer, and the second catalyst layer 4 ′ is an anode catalyst layer, the thickness of the first catalyst layer 4 is The thickness is preferably 10 to 100 μm, and more preferably 15 to 50 μm. The thickness of the second catalyst layer 4 ′ is preferably 20 to 200 μm, and more preferably 30 to 100 μm.

When the membrane / electrode assembly is for a polymer electrolyte fuel cell (PEFC), the amount of catalyst supported in the first catalyst layer 4 and the second catalyst layer 4 ′ is 0.2 to 1.0 Pt. preferable to be mg / cm ^2, more preferably a 0.3~0.6Pt mg / cm ^2. When the membrane-electrode assembly is for a direct fuel cell (DMFC), the first catalyst layer 4 is a cathode catalyst layer, and the second catalyst layer 4 ′ is an anode catalyst layer, the catalyst in the first catalyst layer 4 the amount of carrier is preferable to be 0.5~5.0Pt mg / cm ^2, more preferably a 0.8~3.0Pt mg / cm ^2. Loading amount of the catalyst in the second catalyst layer 4 'is preferable to be 2.0~8.0Pt-Ru mg / cm ^2, more preferably a 3.0~7.0Pt-Ru mg / cm ^2.

  In the production method of the present invention, the first catalyst layer 4 is formed on the flat surface of the support base material 2, and the second catalyst layer 4 ′ is directly applied onto the electrolyte membrane 1 that is soft and follows. Formed. Therefore, the surface roughness of the surface 4b opposite to the surface 4a in contact with the electrolyte membrane 1 of the first catalyst layer 4 is smaller than the surface roughness of the surface opposite to the surface in contact with the electrolyte membrane 1 of the second catalyst layer 4 ′. The surface roughness (Ra) of the opposite surface 4b of the first catalyst layer 4 is usually 0.05 to 2.0 μm, and the surface roughness (Ra) of the opposite surface of the second catalyst layer is usually 2.5 to 10.0 μm. The surface roughness (Ra) can be measured using, for example, the apparatus described in the examples.

  As the electrolyte membrane 1, known ones can be used. For example, perfluorosulfonic acid-based fluorine ion exchange resin membranes, more specifically, C—H bonds of hydrocarbon-based ion exchange membranes with fluorine are used. Examples include membranes made of proton conductive polymer electrolytes such as substituted perfluorocarbon sulfonic acid polymers (PFS polymers). By introducing a fluorine atom having high electronegativity, it is chemically very stable, the dissociation degree of the sulfonic acid group is high, and high ion conductivity can be realized. Specific examples of such a proton conductive polymer electrolyte membrane include, for example, “Nafion” (registered trademark) manufactured by DuPont, “Flemion” (registered trademark) manufactured by Asahi Glass Co., Ltd., and manufactured by Asahi Kasei Corporation. “Aciplex” (registered trademark), “Gore Select” (registered trademark) manufactured by Gore, and the like.

  The thickness of the electrolyte membrane used for the production of the membrane / electrode assembly is preferably 10 to 250 μm, and more preferably 10 to 80 μm in the case of PEFC. When the membrane / electrode assembly produced according to the present invention is for a direct fuel cell (DMFC), the thickness of the electrolyte membrane is preferably 10 to 200 μm, and more preferably 14 to 100 μm.

  The supporting substrate 2 does not have large irregularities on the surface, and has a flat surface, for example, a thermoplastic resin such as polyethylene terephthalate, polybutylene terephthalate, polyimide, polyamide, acetal resin, polyphenylene oxide polyethylene, polypropylene, etc. The sheet | seat containing the resin sheet which consists of etc., or a rubber-like elastic body is mentioned, The sheet | seat containing a rubber-like elastic body is preferable. If the supporting base material has rubber-like elasticity, the laminated body 10 is made to be an electrolyte without causing a gap between the laminated body 10 composed of the first catalyst layer 4 and the supporting base material 2 and the electrolyte membrane 1. It is easier to adhere to the film 1. In addition, the electrolyte membrane 1 can be fixed to the laminate 10 with a relatively small load due to the tackiness of the rubber-like elastic body.

  Examples of the rubber-like elastic material include natural rubber, styrene rubber, butyl rubber, chloroprene rubber, silicon rubber, urethane rubber, fluorine rubber, acrylic rubber, nitrile rubber, and styrene butadiene rubber. In particular, there is no generation of decomposition products even when contacted with a chemically active first catalyst layer, and there is no deterioration in battery performance and durability due to the transfer of decomposition products to the first catalyst layer. Silicon rubber or fluoro rubber, which is stable, is more preferable. When the support substrate 2 is a sheet containing a rubber-like elastic body, the whole may be made of a rubber-like elastic body, but may be a laminate of a sheet-like rubber-like elastic body and a film or the like. Further, when the support base 2 includes silicon rubber or fluororubber, the whole may be formed of silicon rubber or fluororubber, but at least the surface of the support base 2 in contact with the first catalyst layer 4 is It only needs to contain silicon rubber or fluorine rubber.

  The surface roughness (Ra) of the surface of the support substrate 2 on which the first catalyst-containing paste is applied is usually preferably 0.05 to 2.0 μm and more preferably 0.5 to 1.5 μm. preferable. The surface roughness (Ra) can be measured using, for example, the apparatus described in the examples.

  The thickness of the support substrate 2 is preferably 20 μm to 1000 μm, more preferably 50 μm to 300 μm, from the reason that the handleability and adaptability to a roll to roll compatible winding device are good.

  When the support base material 2 has rubber-like elasticity, the rubber hardness measured according to JIS K 6253 of the support base material 2 is preferably 20 to 80, and more preferably 40 to 60. When the rubber hardness of the support base material 2 is 20 to 80, the support base material 2 has an appropriate tackiness that enables the electrolyte membrane 1 to be fixed to the support base material 2 and is coated with the second catalyst-containing paste. Even if a tension to expand the generated electrolyte membrane 1 is generated, it is possible to prevent the electrolyte membrane 1 from being peeled off from the support base material 2 and to be wrinkled.

  As the 1st electrode base material 7 and the 2nd electrode base material 5, a well-known thing can be used. For example, a porous conductive substrate that can efficiently supply fuel gas or the like as fuel to the first catalyst layer 4 and the second catalyst layer 4 ′, more specifically, carbon paper or carbon cloth is used. be able to.

The thermocompression bonding (hot press) of the electrolyte membrane 1 to the laminated body 10 can be performed by, for example, using a roll press or a flat press to pressurize the electrolyte membrane 1 while heating it and press it against the laminated body 10. Pressure applied to the first catalyst layer during the thermocompression bonding, preferable to be 1~100kgf / cm ^2, more preferably a 10~50kgf / cm ^2. The temperature of the press machine surface is preferably 80 to 200 ° C, more preferably 100 to 170 ° C.

  The method for producing a membrane / electrode assembly of the present invention can be applied to the production of a membrane / electrode assembly of a polymer electrolyte fuel cell (PEFC), a membrane / electrode assembly of a direct fuel cell (DMFC), etc. In particular, it can be suitably applied to the production of DMFC membrane-electrode assemblies. The reason is explained below.

  The catalyst layer of the DMFC cathode needs to have a structure with good gas diffusibility. The thickness of the cathode catalyst layer is relatively thin. Therefore, it is preferable that the catalyst layer of the cathode is formed on the flat surface of the support base material having good shape stability, rather than being formed on the soft and followable electrolyte membrane.

  On the other hand, since the DMFC anode reacts with a liquid, it does not require as high a gas diffusivity as the cathode, but since a reaction for generating protons is performed, a proton conduction path needs to be well formed. . Further, since the catalyst layer of the anode has a large amount of catalyst, for example, when the anode catalyst layer formed on the support substrate is transferred to the electrolyte membrane, the catalyst may be lost. Further, the catalyst contained in the catalyst layer of the anode has poor transferability, for example, one or more metals selected from the group consisting of ruthenium, rhodium, palladium, iron, nickel, cobalt, gold and platinum and platinum. And platinum-ruthenium is particularly preferably used.

  From the above, after forming the cathode catalyst layer (first catalyst layer) on the flat surface of the support substrate, the catalyst layer is transferred to the electrolyte membrane, and the anode catalyst layer (second catalyst layer) The production method of the present invention in which is formed on the electrolyte membrane by direct coating can be particularly preferably applied to the production of a membrane / electrode assembly of a direct fuel cell (DMFC).

  EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to these examples.

  The surface roughness (Ra) was measured using a ZYGO (USA) non-contact three-dimensional surface roughness meter (New View 5032).

[Example 1]
A part of one of the main surfaces (surface roughness (Ra) 0.2 μm) of the PET support substrate (Toray S10, thickness 180 μm) is cut out corresponding to the planar shape of the first catalyst layer. Then, the cathode catalyst-containing paste having the following composition was sprayed on the exposed portion of the PET support substrate, and the coated cathode catalyst-containing paste was dried to obtain a first catalyst layer (thickness 82 μm). ) Was formed. The cathode catalyst-containing paste was applied so that the amount of Pt supported was 1.0 mg / cm ² . The thickness of the PET supporting substrate was measured using a digital meter M-30 (manufactured by Sony Corporation).
[Composition of cathode catalyst-containing paste]
Catalyst (TEC10E50E, Tanaka Kikinzoku Co., Ltd.) 1 part by weight electrolyte (NafionDE2020CS, DuPont) 0.5 part by weight Water 3 parts by weight Isopropanol 3 parts by weight 1-butanol 3 parts by weight

Next, an electrolyte membrane (Nafion117, manufactured by DuPont) is placed on the first catalyst layer, the first catalyst layer is embedded in the electrolyte membrane by hot pressing (110 ° C., 30 kgf / cm ² ), and PET support is provided. The electrolyte membrane was thermocompression bonded to the laminate, and the electrolyte membrane and the first catalyst layer were bonded so that no gap was generated between the laminate comprising the base material and the first catalyst layer and the electrolyte membrane.

Next, a tencil mask partially cut out corresponding to the planar shape of the second catalyst layer is overlaid on the surface opposite to the surface of the electrolyte membrane on the side of the PET support substrate, and the following composition is formed on the exposed portion of the electrolyte membrane. After the anode catalyst-containing paste was applied by spraying, the applied anode catalyst-containing paste was dried to form a second catalyst layer (thickness: 170 μm). The anode catalyst-containing paste was applied so that the supported amount of Pt—Ru was 3.0 mg / cm ² . Next, the PET support base material was peeled from the first catalyst layer. The surface roughness (Ra) of the first catalyst layer opposite to the surface in contact with the electrolyte membrane is 0.6 μm, and the surface roughness (Ra) of the second catalyst layer opposite to the surface in contact with the electrolyte membrane is 3 μm.
[Composition of anode catalyst-containing paste]
Catalyst (TEC81E81, Tanaka Kikinzoku Co., Ltd.) 1 part by weight electrolyte (NafionDE2020CS, DuPont) 0.5 part by weight Water 3 parts by weight n-butanol 6 parts by weight

  According to the method for manufacturing a fuel cell membrane / electrode assembly of the present invention, it is possible to provide a fuel cell membrane / electrode assembly capable of easily forming a catalyst layer while suppressing swelling of the electrolyte membrane. The method for producing a membrane-electrode assembly for a fuel cell of the invention is particularly useful for producing a membrane-electrode assembly constituting a direct methanol fuel cell.

FIG. 1 is a schematic cross-sectional view of an example of the membrane / electrode assembly of the present invention. 2 is a schematic cross-sectional view of a three-layer MEA constituting the membrane-electrode assembly shown in FIG. 3A to 3E are process schematic cross-sectional views illustrating an example of a method for producing a membrane-electrode assembly for a fuel cell according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electrolyte membrane 2 Support base material 4 1st catalyst layer 4 '2nd catalyst layer 5 2nd electrode base material 7 1st electrode base material 8 Air electrode 6 Fuel electrode 10 Laminated body

Claims (8)

Applying a first catalyst-containing paste to a support substrate, drying the applied first catalyst-containing paste, and forming a first catalyst layer;
The first electrolyte layer is embedded in the electrolyte membrane, and the electrolyte membrane is formed so that no voids are formed between the electrolyte membrane and the laminate including the support base and the first catalyst layer. A step of thermocompression bonding to the laminate, and bonding the electrolyte membrane and the first catalyst layer;
Applying a second catalyst-containing paste to the opposite surface of the electrolyte membrane on the side of the support substrate, and drying the applied second catalyst-containing paste to form a second catalyst layer;
Peeling the support substrate from the first catalyst layer. A method for producing a membrane / electrode assembly for a fuel cell.   2. The method for producing a membrane-electrode assembly for a fuel cell according to claim 1, wherein the first catalyst layer is a cathode catalyst layer, and the second catalyst layer is an anode catalyst layer.   The method for producing a membrane / electrode assembly for a fuel cell according to claim 1 or 2, wherein the support substrate contains a rubber-like elastic body.   The method for producing a membrane / electrode assembly for a fuel cell according to any one of claims 1 to 3, wherein the support substrate has a rubber hardness measured in accordance with JIS K 6253 of 20 to 80.   The method for producing a membrane / electrode assembly for a fuel cell according to any one of claims 1 to 4, wherein a surface of the support base that is in contact with the first catalyst layer contains silicon rubber or fluorine rubber.   The method for producing a membrane / electrode assembly for a fuel cell according to any one of claims 1 to 5, wherein the support substrate has a thickness of 20 µm to 1000 µm. A fuel cell membrane / electrode assembly formed by the fuel cell membrane / electrode assembly manufacturing method according to any one of claims 1 to 6,
The electrolyte membrane;
The second catalyst layer disposed in contact with one main plane of the electrolyte membrane;
The first catalyst layer embedded in the electrolyte membrane from the opposite side of the electrolyte membrane to the second catalyst layer side,
A membrane / electrode assembly for a fuel cell, wherein a surface opposite to the one main plane of the electrolyte membrane and a surface opposite to the surface of the first catalyst layer facing the second catalyst layer are substantially in the same plane.   The surface roughness of the surface of the first catalyst layer opposite to the surface in contact with the electrolyte membrane is smaller than the surface roughness of the surface of the second catalyst layer opposite to the surface in contact with the electrolyte membrane. Membrane / electrode assembly.

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