JP2014192016A - Membrane electrode assembly, fuel cell employing the same, and manufacturing method of membrane electrode assembly - Google Patents

Abstract

Disclosed is a membrane electrode assembly which is excellent in durability, flat and easy to handle.
SOLUTION: A fuel electrode catalyst layer 6 and an air electrode catalyst layer 7 are arranged opposite to each other on a polymer electrolyte membrane 10, and gasket members 8 and 9 are arranged around the catalyst layers 6 and 7, respectively. In the membrane electrode assembly 1, the catalyst layers 6 and 7 are divided into two regions 61, 71, 62, and 72 having different surface roughnesses, and the two regions 61, 71, 62, and 72 occupy the central portion. The first catalyst layers 61 and 71 and the second catalyst layers 62 and 72 surrounding the first catalyst layers 61 and 71 so as to border the periphery of the first catalyst layers 61 and 71 with a predetermined width W. The width W of the layers 62 and 72 is 0.1 mm to 1 mm. The surface roughness SRa of the first catalyst layers 61 and 71 is 0.01 μm to 0.80 μm, and the surface roughness SRa of the second catalyst layers 62 and 72 is the surface of the first catalyst layer 62. It is larger than the roughness SRa.
[Selection] Figure 2

Description

  The present invention relates to a membrane electrode assembly of a polymer fuel cell and a fuel cell using the same.

  In recent years, a fuel cell (hereinafter also referred to as a fuel cell) has attracted attention as a countermeasure for environmental problems and energy problems. A fuel cell is one that obtains electricity by converting chemical energy associated therewith into electric energy in a reaction of oxidizing a reducing gas such as hydrogen or methane with an oxidizing gas such as oxygen or air. This fuel cell is considered to be a clean energy source because there are abundant substances that can be used as fuel and because the power generation is only water.

  Fuel cells are classified into alkaline, phosphoric acid, polymer, molten carbonate, solid oxide, etc., depending on the type of electrolyte. Among these classifications, polymer fuel cells (PEFC) have low temperature operation, high power density, and can be reduced in size and weight. It is expected to be used as an on-vehicle power source.

The polymer fuel cell includes a fuel electrode (anode catalyst layer) provided on one surface of a polymer electrolyte membrane and an air electrode (cathode catalyst layer) provided on the other surface. The membrane electrode assembly has a structure in which the anode catalyst layer and the cathode catalyst layer are arranged so as to face each other. When this polymer fuel cell generates electric power, a fuel gas containing hydrogen is supplied to one fuel electrode side, and an oxidant gas containing oxygen is supplied to the other air electrode side. The supplied fuel gas becomes protons and electrons in the anode catalyst layer. The proton means a hydrogen ion (H ⁺ ), that is, ionized hydrogen in the chemical domain. The protons move to the cathode catalyst layer side through the polymer electrolyte and the polymer electrolyte membrane in the anode catalyst layer. Further, the electrons move through the external circuit to the cathode catalyst layer in the same manner as the proton described above. In the cathode catalyst layer, protons, electrons, and an oxidant gas supplied from the outside react to generate water. As described above, the polymer fuel cell continuously generates a charge at the fuel electrode and the air electrode, and thus can continuously generate electric charge and functions as a battery.

  Generally, wet or dry coating or a transfer method is used for the production of a membrane electrode assembly. Among them, an excellent production method is known that can obtain a membrane electrode assembly excellent in adhesion of a catalyst layer and advantageous in power generation performance and durability without requiring a complicated apparatus. The manufacturing method of the membrane electrode assembly is a method by wet coating in which the material constituting the catalyst layer and the slurry made of an appropriate solvent or dispersion medium are directly applied to the electrolyte membrane.

However, this wet coating method inevitably causes swelling of the electrolyte membrane due to the slurry solvent and subsequent shrinkage due to drying. Therefore, it is very difficult to form the catalyst layer in a desired shape.
Further, in the membrane electrode assembly, gas leakage due to the difference in thickness between the region where the catalyst layer is formed in the electrolyte membrane and the region where the catalyst layer is not formed, and intensive deterioration of the region where the catalyst layer is not formed in the electrolyte. In order to prevent this, a configuration in which a gasket member (hereinafter also simply referred to as a gasket) is provided at least on the electrolyte membrane or outside the catalyst layer is often seen.

  In addition, a method for producing a membrane electrode assembly with a gasket member, in which a catalyst layer is formed in a shape almost as designed, is also known. For example, the manufacturing method of the electrolyte membrane composite which consists of the electrolyte and masking member of patent document 1 is known. Patent Document 1 discloses a method in which a masking member having an opening is disposed on an electrolyte membrane, and the catalyst layer slurry is directly applied to the electrolyte membrane. That is, by laminating a masking member and a gasket member, a membrane electrode assembly with a gasket member can be easily obtained.

Japanese Patent No. 4737924

  However, according to the method described in Document 1, the gap between the gasket member and the catalyst layer cannot be completely eliminated. When there is a region where the electrolyte membrane is exposed in this manner, there is a problem that the region where the electrolyte membrane is exposed is accelerated in deterioration due to power generation and the durability is lowered. The present invention has been made in view of such problems, and the object of the present invention is to provide a membrane electrode assembly that has no electrolyte membrane exposure, is excellent in durability, is flat and easy to handle, and a fuel using the same To provide a battery.

The present invention has been made to achieve such an object, and the invention according to claim 1 is characterized in that the catalyst layers (6, 7) are arranged to face both sides of the polymer electrolyte membrane (10). A membrane electrode assembly (1) in which gasket members (8, 9) are arranged around each catalyst layer (6, 7), and the catalyst layers (6, 7) have two regions with different surface roughnesses. (61, 71) (62, 72)
The two regions (61, 71) (62, 72) have a first catalyst layer (61, 71) occupying a central portion and a predetermined width (W) around the first catalyst layer (61, 71). ), And the width (W) of the second catalyst layer (62, 72) is 0.1 mm to 1 mm. Features.

The invention according to claim 2 is the invention according to claim 1, wherein the surface roughness (SRa) of the first catalyst layer (61, 71) is 0.01 um to 0.80 um, The surface roughness (SRa) of the second catalyst layer (62, 72) is larger than the surface roughness (SRa) of the first catalyst layer (62).
The invention according to claim 3 is the invention according to claim 1 or 2, wherein the surface roughness (SRa) of the second catalyst layer (62, 72) is 1.0 um or less. Features.

The invention according to claim 4 is the invention according to any one of claims 1 to 3, wherein the gasket member (8, 9) is made of a film-like material. .
The invention according to claim 5 is the invention according to any one of claims 1 to 4, wherein the thickness of the first catalyst layer (61) is set between the fuel electrode and the air electrode. In contrast, the width (W) of the second catalyst layer (62) is 0.1 mm to 0.7 mm in the fuel electrode and 0.3 mm to 1 mm in the air electrode.

The invention according to claim 6 is a fuel cell using the membrane electrode assembly (1) according to any one of claims 1 to 5.
In the invention according to claim 7, the catalyst layers (6, 7) are arranged to face both surfaces of the polymer electrolyte membrane (10), and gasket members (6, 7) are disposed around the respective catalyst layers (6, 7). 8, 9) is a method for producing a membrane electrode assembly (1), wherein the catalyst layer (6, 7) is divided into two regions (61, 71) (62, 72) having different surface roughnesses. The two regions (61, 71) (62, 72) are formed around the first catalyst layer (61, 71) after forming the first catalyst layer (61, 71) occupying the central portion. A second catalyst layer (62, 72) is formed so as to be bordered with a width of 0.1 mm to 1 mm.

  ADVANTAGE OF THE INVENTION According to this invention, an electrolyte membrane is not exposed, it is excellent in durability, and it can provide a flat and easy-to-handle membrane electrode assembly and a fuel cell using the same. More specifically, the following effects 1) to 3) are obtained.

1) By forming the second catalyst layer, a decrease in durability due to the exposure of the electrolyte membrane is suppressed.
2) The second catalyst layer borders the edge around the first catalyst layer with a predetermined width, and has a structure in which the roughness of the catalyst layer surface at the edge is different. It is possible to prevent local degradation of the edge during time or repeated operation.
3) By setting the width of the second catalyst layer bordering the edge of the first catalyst layer to 0.1 mm to 1 mm over all four sides, the electrolyte membrane swells and contracts with the formation of the second catalyst layer The distortion of the membrane electrode assembly due to the above can be avoided.

It is a disassembled perspective view for demonstrating the fuel cell (cell) which concerns on embodiment of this invention. It is the upper surface, side surface, and lower surface of the membrane electrode assembly which concerns on embodiment of this invention. It is an example of the image which observed the roughness curved surface of the catalyst layer surface of a membrane electrode assembly with the laser microscope.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an exploded perspective view for explaining a fuel cell (cell) according to an embodiment of the present invention. As illustrated in FIG. 1, a polymer fuel cell (hereinafter also simply referred to as a fuel cell) includes a membrane electrode assembly 1, diffusion layers 2 and 3, and separators 4 and 5. Yes. The membrane electrode assembly 1 is sandwiched between the diffusion layers 2 and 3. Further, the outer surfaces of the diffusion layers 2 and 3 are sandwiched between the separators 4 and 5. The surfaces of the separators 4 and 5 face each other along the diffusion layers 2 and 3 of the air electrode and the fuel electrode, and gas flow paths 41 through which the respective reaction gases (hereinafter also referred to as source gases) flow. , 51 is a comb-shaped structure. This comb-shaped structure is a structure in which a plurality of parallel grooves are formed on the surfaces facing each of the diffusion layers 2 and 3 by providing protrusions at equal intervals. In many cases, the cooling water flow path is constituted by such a groove. The separators 4 and 5 are made of a material that is conductive and does not transmit gas. As the material of the separators 4 and 5, for example, a metal plate subjected to corrosion resistance or a carbon-based material such as baked carbon is used.

  First, the oxidant gas and the fuel gas of the fuel cell pass through the gas flow paths 41 and 51 of the separators 4 and 5. The reaction gas is supplied to the membrane electrode assembly 1 through the diffusion layers 2 and 3 while passing through the flow paths 41 and 51. The diffusion layers 2 and 3 are made of a material having high conductivity and high diffusibility of the source gas. For example, a metal film, a conductive polymer, a carbon material, and the like can be given. Among these materials, porous conductor materials such as carbon paper are preferable. The thickness of the diffusion layers 2 and 3 is preferably about 50 μm to 1000 μm.

  FIG. 2 shows an upper surface, a side surface, and a lower surface of the membrane electrode assembly according to the embodiment of the present invention. As shown in FIG. 2, the fuel electrode catalyst layer 6 is formed on the upper surface of the electrolyte membrane 10, and the air electrode catalyst layer 7 is formed on the lower surface of the electrolyte membrane 10. That is, both surfaces of the electrolyte membrane 10 are sandwiched between the catalyst layers 6 and 7. Gasket members 8 and 9 are arranged so as to border the outer edges of the catalyst layers 6 and 7 without leaving a gap with the outer edges of the catalyst layers 6 and 7. By forming the second catalyst layers 62 and 72 as described above, it is possible to suppress a decrease in durability due to the exposure of the electrolyte membrane 10.

  The material of the electrolyte membrane 10 is not particularly limited as long as it is for a material having high ion conductivity, but in many cases, a perfluorosulfonic acid-based or hydrocarbon-based solid polymer electrolyte membrane is used. Specifically, DuPont's Nafion (registered trademark), Japan Gore-Tex's Goreselect (registered trademark), Asahi Glass Co., Ltd.'s Flemion (registered trademark), etc. Is mentioned. The thickness of the electrolyte membrane 10 is not particularly limited, but is preferably 10 μm to 200 μm. If it is thinner than this, it is difficult to handle because it is easily damaged, and if it is thicker, the membrane resistance increases and causes a problem in performance.

  The fuel electrode catalyst layer 6 according to the present embodiment includes a catalyst and an electrolyte, and includes a first catalyst layer 61 and a second catalyst layer 62 according to the present invention. Similarly, the fuel electrode catalyst layer 7 according to the present embodiment includes a catalyst and an electrolyte, and includes a first catalyst layer 71 and a second catalyst layer 72 according to the present invention. Catalyst particles include platinum, palladium, ruthenium, iridium, rhodium, osmium, platinum group elements, metals such as iron, lead, copper, chromium, cobalt, nickel, manganese, vanadium, molybdenum, gallium, and aluminum Alloys, oxides and double oxides can be used.

  Although the catalyst particles may be used alone, it is preferable to use them supported on a conductive carrier. The conductive carrier is not particularly limited as long as it is in the form of fine particles and has conductivity and chemical resistance. As this conductive carrier, carbon particles are generally used, and examples thereof include carbon black, graphite, graphite, activated carbon, carbon fiber, carbon nanotube, fullerene and the like. The particle size of these carbon particles is preferably about 10 nm to 1000 nm. When the particle size of the carbon particles is smaller than 10 nm, it is difficult to form an electron conduction path. Conversely, when the particle size is larger than 1000 nm, the thickness of the electrode catalyst layers 6 and 7 increases and the electric resistance increases. .

  Moreover, the electrolyte used for the catalyst layers 6 and 7 should just have ion conductivity. Moreover, it is preferable to use the same material for the electrolyte used for the catalyst layers 6 and 7 and the electrolyte membrane 10. In this case, the adhesion between the catalyst layers 6 and 7 and the electrolyte membrane 10 is improved, so that the performance of the fuel cell can be improved. The means for forming the first catalyst layers 61 and 71 is not particularly limited. For example, the slurry in which the mixture of the catalyst particles, the carrier, and the electrolyte is dispersed directly on the electrolyte membrane 10; Any of the transfer methods may be used in which the transfer substrate or the diffusion layers 2 and 3 are coated and then formed by transfer.

Further, the means for forming the second catalyst layers 62 and 72 is preferably a wet coating method. Among the direct wet coating methods, a dispenser printing method and an ink jet printing method that are easier to apply to a predetermined position are suitable.
Then, a drying process is provided as necessary in the formation of the first catalyst layers 61 and 71 and the formation of the second catalyst layers 62 and 72. The drying method in the drying step is not particularly limited, and examples thereof include warm air drying, infrared drying, and reduced pressure drying.

  Moreover, the solvent or dispersion medium of the slurry for forming the second catalyst layers 62 and 72 is not particularly limited, but may be one that can dissolve or disperse the electrolyte. In general, water, alcohols, ketones, amines, esters, ethers and glycol ethers are suitable. A mixture of these solvents or dispersion media in various proportions is often used.

  The gasket members 8 and 9 are required to have a uniform thickness and small deformation when a pressure is applied, and those composed of films are suitable. The gasket members 8 and 9 made of a film include an adhesive layer or an adhesive layer on at least one surface of the film, and may include a release layer on the other surface. The pressure-sensitive adhesive layer or adhesive layer is provided between the film and the electrolyte membrane 10 and improves the gas sealability at the interface. The release layer facilitates removal of the catalyst slurry applied to the surfaces of the gasket members 8 and 9 when the second catalyst layers 62 and 72 are formed. The material of the gasket members 8 and 9 is preferably a material that does not easily deform even when pressure is applied, and examples thereof include polymer materials such as polyethylene terephthalate, polyethylene naphthalate, polycarbonate, and polyamide. These may be used alone or in combination.

  In the membrane electrode assembly 1, for example, after the first catalyst layers 61 and 71 are formed on the electrolyte membrane 10, the gasket members 8 and 9 are bonded together, and then the catalyst layers 61 and 71 and the gasket members 8 and 9 are bonded. And the second catalyst layers 62 and 72 are formed in this order. Alternatively, after the gasket members 8 and 9 are bonded to the electrolyte membrane 10, the first catalyst layers 61 and 71 and then the second catalyst layers 62 and 72 may be formed in this order. Thus, as an example of the method for producing the membrane electrode assembly 1, it is preferable to form the second catalyst layer 62 after forming the first catalyst layer 61.

  In the membrane electrode assembly 1 according to this embodiment, a fuel electrode catalyst layer 6 and an air electrode catalyst layer 7 are disposed on both sides of a polymer electrolyte membrane 10 so as to face each other. The gasket members 8 and 9 are arranged on the surface. The catalyst layers 6 and 7 are divided into two regions 61, 71, 62 and 72 having different surface roughnesses. The two regions 61, 71, 62, 72 surround the first catalyst layers 61, 71 occupying the central portion, and the second surrounding the periphery of the first catalyst layers 61, 71 with a predetermined width W. Catalyst layers 62, 72. The width W of the second catalyst layers 62 and 72 is 0.1 mm to 1 mm. Thus, by setting the width W of the second catalyst layer bordering the edge of the first catalyst layer to 0.1 mm to 1 mm over all four sides, the electrolyte membrane accompanying the formation of the second catalyst layer Distortion of the membrane electrode assembly due to swelling and shrinkage can be avoided.

  The first catalyst layers 61 and 71 are formed on a small flat area on the electrolyte membrane 10 that is Wmm inside the flat area on which the catalyst layer is to be formed. Further, the second catalyst layers 62 and 72 are formed in a wide flat area outside the outer edges of the first catalyst layers 61 and 71 by Wmm. The range of W is 0.1 mm to 1 mm. When the value of W is smaller than 0.1 mm, it becomes difficult to apply the catalyst layer slurry accurately only at a predetermined position. Conversely, when the value of W is greater than 1 mm, the amount of slurry applied increases, so that the dimensional change due to drying and the dimensional change due to swelling of the electrolyte membrane 10 become so large that they cannot be ignored. As a result, the membrane electrode assembly 1 is distorted.

  Further, since the air electrode has a larger overvoltage than the fuel electrode, it is also known that a large amount of the catalyst layer 7 is formed by the air electrode. In this case, the value of W is preferably set to 0.1 mm to 0.7 mm at the fuel electrode and 0.3 mm to 1 mm at the air electrode. Since it is necessary to use a slurry having a low solid content concentration at the fuel electrode, when applied in a range exceeding 0.7 mm, swelling due to the solvent tends to occur. In addition, it is difficult to apply a thicker slurry to a width W lower than 0.3 mm using the same mechanism as that of the fuel electrode, but if it is 0.3 mm, it can be easily formed without special measures. can do. The thickness of the first catalyst layer 61 is different between the fuel electrode and the air electrode, and the width W of the second catalyst layer 62 is 0.1 mm to 0.7 mm at the fuel electrode and 0.3 mm at the air electrode. ~ 1 mm.

  The surfaces of the first catalyst layers 61 and 71 have a surface roughness (SRa) smaller than that of the second catalyst layers 62 and 72. This difference in surface roughness is attributed to the coating method, slurry composition, drying conditions, and the like. The relatively rough surface of the catalyst layer edge prevents local deterioration of the edge, which is advantageous in terms of durability. The surface roughness SRa of the first catalyst layers 61 and 71 is 0.01 μm to 0.80 μm, and the surface roughness SRa of the second catalyst layers 62 and 72 is the surface of the first catalyst layer 62. It is larger than the roughness SRa. The second catalyst layers 62 and 72 border the edges around the first catalyst layer with a predetermined width W. By making the surface roughness of the catalyst layers 6 and 7 different at the edge, it is possible to prevent local deterioration of the edge even when the operation is performed for a long time or repeatedly.

The surface roughness (SRa) of the first catalyst layer is 0.01 to 0.8 um. If it is less than 0.01 um, the diffusibility of gas or water is poor, and if it is more than 0.8 um, the contact resistance at the joint surface between the catalyst layer and the diffusion layer increases, leading to a decrease in battery performance. The surface roughness SRa of the second catalyst layers 62 and 72 is 1.0 μm or less.
Since the area of the second catalyst layer is small and the influence of the contact resistance is small, it may exceed 0.8 um, but if it exceeds 1.0 um, battery performance is deteriorated.

FIG. 3 is an example of an image obtained by observing the roughness curved surface of the catalyst layer surface of the membrane electrode assembly according to the embodiment of the present invention with a scanning laser microscope (Confocal laser scanning microscope). Hereinafter, the scanning laser microscope is also simply referred to as a laser microscope. The surface roughness (SRa) of the catalyst layer surface of the present embodiment as shown in FIG. 3 is calculated based on the following equation (1) from a roughness curved surface obtained using a laser microscope.
SRa = (1 / LM) ∬f (x, y) dxdy (1)
Note that the x, y, and z coordinate axes shown in FIG. 3 are a z-up coordinate system in which the z axis faces upward. The length of the roughness curved surface in the x direction is L, the length in the y direction is M, and the roughness curved surface is z = f (x, y). That is, the average value of the absolute values of the elevation of the roughness curved surface indicated by the arrow at the top of FIG.

  In this embodiment, the surface roughness (SRa) of the catalyst layer surface is measured using a laser microscope. FIG. 3 shows an example of a curved surface of the catalyst layer surface obtained by a laser microscope. The laser microscope uses an argon ion laser having an oscillation wavelength of 488 nm. The scanning method is light deflection by two galvanometer scanners, and the scanning range is a 4: 3 rectangular area inscribed in a circle with 16 fields of view. The pinhole is a circular pinhole, a z-revolver up-down method, and an image rotator is an image rotation angle ± 90 °.

  In a scanning laser microscope, a laser beam is narrowed down to a minute spot by an objective lens, and a sample is scanned in the xy directions. Then, the light from the sample surface is captured by the detector, and the sample image is displayed and output on the monitor. In the confocal optical system, light from other than the in-focus position is excluded by arranging a pinhole at a position that can be optically conjugate with the in-focus position. Therefore, these lights are dark in the image, and a sample having a step can be optically sliced, and a rough curved surface of the catalyst layer surface can be obtained.

  As described above, the membrane electrode assembly 1 according to the present embodiment and the fuel battery cell including the membrane electrode assembly 1 have been described. However, the membrane electrode assembly 1 is not applied only to the fuel battery cell. Examples of the present invention will be described in detail below, but the present invention is not limited to the following examples.

As catalyst layer slurry, platinum-supported carbon (TEC10E50E, Tanaka Kikinzoku) and water are mixed, and then 2-propanol (2-propanol) and an electrolyte (Nafion (registered trademark) dispersion, Wako Pure Chemical Industries, Ltd.) are mixed therewith. In addition, what was obtained by stirring was used.
Adhesive layer-attached PET film (biaxially stretched PET (polyethylene terephthalate)) having an opening (size 50 mm × 50 mm) is attached to both surfaces of an electrolyte membrane (Nafion (registered trademark) 211CS, DuPont) as gasket members 8 and 9. The attached membrane was an electrolyte membrane with gasket members 8 and 9.

  The membrane electrode assembly 1 was manufactured by applying the slurry for the catalyst layer to the electrolyte membrane 10 to which the gasket members 8 and 9 were attached with a doctor plate, and further drying in a furnace at 100 ° C. At this stage, the gap between the gasket members 8 and 9 and the catalyst layers 6 and 7 could not be eliminated, and the narrowest gap was 0.08 mm. Furthermore, the membrane electrode assembly 1 having the first catalyst layers 61 and 71 in the inner range with a gap of 0.5 mm or 2 mm from the edge of the gasket members 8 and 9 was obtained. These are referred to as Comparative Examples 1, 2, and 3.

  Furthermore, the second catalyst layers 62 and 72 having a width W of 2 mm, 0.5 mm, or 0.08 mm are formed by the dispenser printing method and drying in the furnace at 100 ° C., and the first catalyst layers 61 and 62 are formed. And the membrane electrode assembly 1 which has the 2nd catalyst layers 62 and 72 was manufactured. These are referred to as Comparative Example 4, Example 1 and Comparative Example 5, respectively. In addition, as in Comparative Examples 1 to 3, the membrane electrode assembly 1 was manufactured with a gap of 0.1 mm or 1 mm between the gasket members 8 and 9 and the first catalyst layers 61 and 71. Examples 2 and 3 were obtained by forming a second catalyst layer having a width W of 0.1 mm and 1 mm respectively in the same manner as in Example 1.

  When the surface roughness (SRa) of the catalyst layer surfaces of Comparative Examples 4 and 5 and Examples 1 to 3 was calculated, SRa of the first catalyst layer was 0.3 um, and SRa of the second catalyst layer was 0. It was .5um. Diffusion layers (SIGRACET 35BC, SGL) were arranged on both surfaces of these membrane electrode assemblies 1, and an OCV durability test was performed using a commercially available JARI standard cell. The cell temperature was 100 ° C., and humidified hydrogen was supplied to the fuel electrode and humidified oxygen was supplied to the cathode. The test results are shown in Table 1 with the endurance time exceeding 25 hours qualified (O) and the case where the durability time does not exceed unqualified (X).

As shown in Table 1, Comparative Examples 1 to 5 were all unqualified in terms of durability, and Examples 1 to 3 were qualified.
From this test result, it was confirmed that the membrane electrode assembly according to the present invention was excellent in durability.

DESCRIPTION OF SYMBOLS 1 Membrane electrode assembly 2, 3 Diffusion layer 4, 5 Separator 6 Fuel electrode catalyst layer 7 Air electrode catalyst layer 8, 9 Gasket member 10 Electrolyte membrane 41, 51 Gas flow path 61 First catalyst layer 62 of fuel electrode Fuel electrode second catalyst layer 71 Air electrode first catalyst layer 72 Air electrode second catalyst layer W Width of second catalyst layer

Claims (7)

A membrane electrode assembly in which a catalyst layer is disposed opposite to both surfaces of a polymer electrolyte membrane, and a gasket member is disposed around each catalyst layer,
The catalyst layer is divided into two regions with different surface roughness,
The two regions are composed of a first catalyst layer that occupies a central portion and a second catalyst layer that surrounds the first catalyst layer with a predetermined width around the periphery of the first catalyst layer,
The width | variety of this 2nd catalyst layer is 0.1 mm-1 mm, The membrane electrode assembly characterized by the above-mentioned. The surface roughness (SRa) of the first catalyst layer is 0.01 um to 0.80 um,
The membrane electrode assembly according to claim 1, wherein the surface roughness (SRa) of the second catalyst layer is larger than the surface roughness (SRa) of the first catalyst layer.   The membrane electrode assembly according to claim 1 or 2, wherein the surface roughness (SRa) of the second catalyst layer is 1.0 um or less.   The membrane electrode assembly according to any one of claims 1 to 3, wherein the gasket member is made of a film-like material. The thickness of the first catalyst layer is different between the fuel electrode and the air electrode,
5. The width according to claim 1, wherein the width of the second catalyst layer is 0.1 mm to 0.7 mm at the fuel electrode and 0.3 mm to 1 mm at the air electrode. The membrane electrode assembly as described.   A fuel cell using the membrane electrode assembly according to any one of claims 1 to 5. A method for producing a membrane electrode assembly in which a catalyst layer is disposed opposite to both surfaces of a polymer electrolyte membrane, and a gasket member is disposed around each catalyst layer,
The catalyst layer is divided into two regions with different surface roughness,
The two regions are formed after forming the first catalyst layer occupying the central portion.
A method for producing a membrane electrode assembly, comprising: forming a second catalyst layer that surrounds the first catalyst layer with a width of 0.1 mm to 1 mm.

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