JP2006294594A - ELECTRODE CATALYST LAYER FOR FUEL CELL AND FUEL CELL USING THE SAME - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrode catalyst layer for a fuel cell that provides an electrode catalyst layer for a fuel cell excellent in drainage.
A fuel cell electrode catalyst layer comprising at least an electrode catalyst in which catalyst particles are supported on a conductive support and a solid polymer electrolyte, wherein the fuel cell electrode catalyst layer is directed in a thickness direction. Thus, the above problem is solved by an electrode catalyst layer for a fuel cell in which the average secondary particle size of the conductive carrier is increased.
[Selection] Figure 1

Description

  The present invention relates to a fuel cell electrode catalyst layer, and more particularly to a fuel cell electrode catalyst layer with improved drainage.

  A fuel cell is a clean power generation system in which the product of an electrode reaction is water in principle and has almost no adverse effect on the global environment. In particular, the polymer electrolyte fuel cell is expected as a power source for electric vehicles because it operates at a relatively low temperature.

  The polymer electrolyte fuel cell generally has a structure in which a membrane-electrode assembly (hereinafter also simply referred to as “MEA”) is sandwiched between separators. The MEA is formed by sandwiching a solid polymer electrolyte membrane between a pair of electrode catalyst layers and a gas diffusion layer. The electrode catalyst layer includes at least an electrode catalyst in which catalyst particles are supported on a conductive carrier mainly composed of carbon and the like, and a solid polymer electrolyte.

  In the solid polymer electrolyte fuel cell, the following electrochemical reaction proceeds. First, hydrogen contained in the fuel gas supplied to the fuel electrode (anode) side is oxidized by the catalyst particles as shown by the following reaction formula (1) to become protons and electrons. Next, the generated protons pass through the solid polymer electrolyte contained in the fuel electrode side electrode catalyst layer and the solid polymer electrolyte membrane in contact with the fuel electrode side electrode catalyst layer, and reach the oxygen electrode side electrode catalyst layer. . Further, the electrons generated in the fuel electrode side electrode catalyst layer are in contact with the conductive carrier constituting the fuel electrode side electrode catalyst layer, and further on the side different from the solid polymer electrolyte membrane of the fuel electrode side electrode catalyst layer. The oxygen electrode side electrode catalyst layer is reached through the gas diffusion layer, the separator and the external circuit. Then, the protons and electrons that have reached the oxygen electrode side electrode catalyst layer react with oxygen contained in the oxidant gas supplied to the oxygen electrode side as shown in the following reaction formula (2) to generate water. In the fuel cell, electricity can be taken out through the above-described electrochemical reaction.

  In the power generation reaction as described above, the amount of water that moves along with the protons that move through the solid polymer electrolyte membrane from the fuel electrode toward the oxygen electrode, and the amount of water that is generated and condensed by the electrode reaction of the oxygen electrode In such a condition, it is difficult for these waters to be quickly discharged from the oxygen electrode to the outside, causing a flooding phenomenon such as closing the void of the oxygen electrode.

As a means for avoiding such flooding phenomenon, Patent Document 1 discloses that a water-repellent polymer adheres to the surface between the gas diffusion layer and the electrode catalyst layer in order to impart water repellency to the gas diffusion layer. A technique for arranging a water-repellent layer made of conductive particles has been proposed.
JP 2003-109611 A

  The problem with fuel cells is the life of the batteries, which is a problem with cost. Battery life is said to be 5000 hours for automobiles and 40,000 hours for home use, and it is required to maintain desired power generation performance over a long period of time. Therefore, in the conventional fuel cell described in Patent Document 1 and the like, further improvement in durability is still desired.

In addition to the above problems, the conventional fuel cell has the following problems. In the fuel cell, as described above, hydrogen is supplied as a fuel gas to the fuel electrode side. When stopping, a gas such as air is supplied to the fuel electrode side to replace the remaining hydrogen on the fuel electrode side. However, if hydrogen does not escape from the fuel electrode and a certain amount of hydrogen remains in the fuel electrode, in the portion where air is not filled with hydrogen at the fuel electrode and the air remains when restarting, 1 / 2O ₂ + 2H ⁺ + 2e ⁻ → H ₂ O reaction occurs. At that time, the acidity in the solid polymer electrolyte membrane changes, and in the oxygen electrode-side electrode catalyst layer, the carbon constituting the conductive support is corroded and lost by the C + 2H ₂ O → CO ₂ + 4H ⁺ + 4e ⁻ reaction.

  When corrosion of the conductive carrier occurs, the porous structure of the electrode catalyst layer is destroyed, and the battery performance is degraded due to a decrease in the diffusibility of the fuel gas and oxygen gas and a decrease or interruption of the proton conduction path in the electrode catalyst layer. In addition, the battery resistance increases due to the decrease in electronic conductivity, which also decreases the battery performance. Furthermore, the battery performance is also lowered by the fusion of the catalyst particles dropped from the conductive carrier to reduce the surface area of the catalyst particles.

  Such a corrosion reaction of the conductive carrier is a reaction that generates carbon dioxide using water as an oxidizing agent. When water tends to stay in the electrode catalyst layer during operation, water tends to accumulate in the electrode catalyst layer even when the battery operation is stopped. Therefore, the water accumulated in the electrode catalyst layer is a driving force that causes a corrosion reaction of the conductive carrier at the time of startup. Therefore, in order to obtain a fuel cell with excellent durability that can maintain desired power generation performance over a long period of time, it is necessary to appropriately construct a drainage structure in the electrode catalyst layer to suppress corrosion of the conductive carrier. There is.

  Then, the objective of this invention is providing the electrode catalyst layer for fuel cells excellent in drainage property.

  The present invention is a fuel cell electrode catalyst layer comprising at least an electrode catalyst in which catalyst particles are supported on a conductive support and a solid polymer electrolyte, and the fuel cell electrode catalyst layer is directed in the thickness direction. Thus, the above problem is solved by an electrode catalyst layer for a fuel cell in which the average secondary particle size of the conductive carrier is increased.

  The electrode catalyst layer for a fuel cell of the present invention can quickly discharge moisture contained in the electrode catalyst layer to the outside by appropriately disposing conductive carriers having different average secondary particle sizes in the electrode catalyst layer. it can. Thus, according to the electrode catalyst layer for fuel cells with improved drainage, not only can the corrosion of the conductive carrier during start-stop be suppressed, but also the flooding phenomenon in the electrode catalyst layer can be prevented. . Therefore, according to the electrode catalyst layer for a fuel cell of the present invention, it is possible to provide a fuel cell with excellent durability capable of realizing stable power generation performance over a long period of time.

  The first aspect of the present invention is a fuel cell electrode catalyst layer comprising at least an electrode catalyst in which catalyst particles are supported on a conductive carrier and a solid polymer electrolyte, as described above, and the fuel cell electrode catalyst layer. Is an electrode catalyst layer for a fuel cell (hereinafter, also simply referred to as “electrode catalyst layer”) in which the average secondary particle diameter of the conductive carrier increases in the thickness direction.

  A conductive carrier generally used as a catalyst carrier exists as secondary particles in which primary particles are aggregated in an electrode catalyst layer. The electrode catalyst layer of the present invention has a configuration in which the porous density of the electrode catalyst layer decreases in the thickness direction by increasing the average secondary particle diameter of the conductive support in the thickness direction. . In general, water tends to move toward a larger pore diameter (gap), that is, less resistance. Therefore, it is possible to promote the movement of moisture and the like generated in the electrode catalyst layer to the outside, and it is possible to obtain a fuel cell electrode catalyst layer excellent in drainage. Moreover, since the electroconductive support | carrier is a fine powder among the materials which comprise an electrode catalyst layer, the porous density in an electrode catalyst layer can be adjusted easily.

  In the electrode catalyst layer of the present invention, in order to increase the average secondary particle diameter of the conductive support in the thickness direction, the average secondary particle diameter of the conductive support increases gradually or stepwise in the thickness direction. Thus, it is preferable to dispose the conductive support in the electrode catalyst layer.

Especially, since the production of the electrode catalyst layer is easy, the electrode catalyst layer is formed by laminating a layer containing a conductive carrier having a predetermined average secondary particle size, and the average secondary particle size of the conductive carrier is It is desirable to increase stepwise in the thickness direction. That is, as a configuration of the electrode catalyst layer of the present invention, at least two layers of the electrode catalyst layer (1) and the electrode catalyst layer (2) are laminated, and the electrode catalyst layer (1) includes A configuration in which the average secondary particle size (D ₁ ) of the conductive carrier is smaller than the average secondary particle size (D ₂ ) of the conductive carrier contained in the electrode catalyst layer (2) is preferably exemplified.

A preferred embodiment of the electrode catalyst layer having such a configuration is shown in FIG. FIG. 1 is a schematic cross-sectional view of an electrode catalyst layer of the present invention, in which two layers of an electrode catalyst layer (1) 121 and an electrode catalyst layer (2) 122 are laminated, and the electrode catalyst layer (1) 121 has an average secondary particle diameter (D ₁ ) of the conductive carrier 101 smaller than an average secondary particle diameter (D ₂ ) of the conductive carrier 102 contained in the electrode catalyst layer (2) 122. It has become. Thus, in this invention, in order to improve the drainage property of an electrode catalyst layer, the particle diameter of an electroconductive support | carrier is enlarged toward the thickness direction in an electrode catalyst layer. In FIG. 1, in the electrode catalyst layer (1) and the electrode catalyst layer (2), in addition to the conductive carriers 101 and 102, catalyst particles supported on the conductive carrier, solid polymer electrolyte, and the like May be included, but is omitted for convenience of explanation.

  The secondary particles of the conductive carrier mean a particle group in which a plurality of primary particles are aggregated as described above. The secondary particles of the conductive carrier mean a particle group in which primary particles are preferably aggregated in an amount of 2 to 30, more preferably 2 to 15.

  The primary particle of the conductive carrier means one particle. The average primary particle diameter of the conductive carrier used in the electrode catalyst layer of the present invention is preferably 5 to 200 nm, more preferably 10 to 100 nm. If the average primary particle size of the conductive support is less than 5 nm, the porosity in the electrode catalyst layer may decrease and sufficient gas diffusivity may not be obtained. It is difficult to uniformly disperse the functional carrier, and gas diffusibility may be reduced.

  In the electrode catalyst layer of the present invention, the average secondary particle diameter of the conductive support is preferably less than 1 μm, more preferably 0.02 to 0.90 μm, and particularly preferably 0.05 to 0.75 μm. . When the average secondary particle diameter exceeds 1 μm, it is difficult to uniformly disperse in the electrode catalyst layer, and not only gas diffusibility is lowered, but also it is difficult to control the thickness of the electrode catalyst layer within an appropriate range. There is a fear. Therefore, in the present invention, the conductive support is disposed so that the average secondary particle diameter is different in the electrode catalyst layer (1) and the electrode catalyst layer (2) so that the average secondary particle diameter is within the above range. To do.

  In the present invention, the average secondary particle diameter of the conductive carrier is measured by using an electron microscope photograph (magnification: 500,000) obtained by photographing five cross sections of the electrode catalyst layer using a scanning electron microscope under the condition of an acceleration voltage of 5 kV. The maximum particle diameter of 50 arbitrary secondary particles in each photograph is measured, and the value obtained from the average value of 5 locations is used. In addition, the average primary particle diameter of the conductive carrier was measured by measuring the particle diameter of 50 arbitrary primary particles in a transmission electron micrograph obtained by photographing the surface of the electrode catalyst layer at five positions in the same manner as described above. The value obtained from the average value of.

The average secondary particle diameter (D ₁ ) of the conductive carrier contained in the electrode catalyst layer (1) and the average secondary particle diameter (D 2) of the conductive carrier contained in the electrode catalyst layer ( ₂ ). The ratio is preferably 0.05 <D ₁ / D ₂ <1, more preferably 0.1 <D ₁ / D ₂ <0.85. Thereby, water can be more efficiently removed from the electrode catalyst layer.

When the electrode catalyst layer has a structure of three or more layers, another electrode catalyst layer may be formed between the electrode catalyst layer (1) and the electrode catalyst layer (2). At this time, the average secondary particle diameter of the electroconductive carrier contained in the electrode catalyst layer between the electrocatalyst layer (1) and the electrode catalyst layer (2) is defined as the value of the electroconductive carrier contained in the electrode catalyst layer (1). The average secondary particle diameter (D ₁ ) is preferably between the average secondary particle diameter (D ₂ ) of the conductive support contained in the electrode catalyst layer (2), and is conductive in the thickness direction. More preferably, the average secondary particle diameter of the functional carrier is increased in a gradient manner.

  The conductive support used in the electrode catalyst layer of the present invention is used as a support for supporting catalyst particles that promote the electrode reaction. The conductive carrier may have any specific surface area for supporting the catalyst particles in a desired dispersed state and has sufficient electronic conductivity as a current collector. The main component is carbon. Preferably there is. Specifically, carbon particles such as carbon black such as ketjen black, channel black, furnace black and thermal black, activated carbon, coke, natural graphite, artificial graphite and the like can be mentioned. In addition, since the carbon particles are excellent in corrosion resistance, graphitized carbon particles are preferably used.

  In the present invention, “the main component is carbon” refers to containing a carbon atom as a main component, and is a concept including both a carbon atom only and a substantially carbon atom. In some cases, elements other than carbon atoms may be included in order to improve the characteristics of the fuel cell. In addition, being substantially composed of carbon atoms means that mixing of impurities of about 2 to 3% by mass or less is allowed.

The specific surface area of the primary particles of the conductive carrier is preferably 20 to 1600 m ² / g, more preferably 80 to 1200 m ² / g. The specific surface area, 20 m 2 / dispersibility of catalyst particles and a solid polymer electrolyte of ^g less than the that to the conductive support is lowered there is a possibility that sufficient power generation performance is obtained, a 1600 m 2 / ^g When it exceeds, there exists a possibility that the effective utilization factor of a catalyst particle and a solid polymer electrolyte may fall on the contrary.

  In each of the electrode catalyst layers such as the electrode catalyst layer (1) and the electrode catalyst layer (2), the average secondary particle diameter of the conductive carrier used is different, but the catalyst particles and solids supported on the conductive carrier are different. The same polymer electrolyte is used. Therefore, in the following, descriptions of the solid polymer electrolyte and catalyst particles in each electrode catalyst layer will be described collectively.

  In the present invention, the above-described conductive carrier is used in the electrode catalyst layer as an electrode catalyst on which catalyst particles are supported.

  Specifically, the catalyst particles are required to have a catalytic action in the oxidation reaction of hydrogen and / or the reduction reaction of oxygen, and those containing at least platinum are preferably used. Further, the catalyst particles may be an alloy of platinum and other metals in order to improve catalyst activity, poisoning resistance to carbon monoxide, heat resistance, and the like. Specifically, the alloy is at least selected from platinum, ruthenium, iridium, rhodium, palladium, osmium, tungsten, lead, iron, chromium, cobalt, nickel, manganese, vanadium, molybdenum, gallium, and aluminum. Examples thereof include alloys with one or more metals. The composition of the alloy is preferably 30 to 90 atomic% for platinum and 10 to 70 atomic% for the metal to be alloyed, depending on the type of metal to be alloyed.

  In general, an alloy is a generic term for a metal element having one or more metal elements or non-metal elements added and having metallic properties. The alloy structure consists of a eutectic alloy, which is a mixture of component elements that form separate crystals, a component element that completely dissolves into a solid solution, and a component element that is an intermetallic compound or a compound of a metal and a nonmetal. There is what is formed, and any may be used in the present application.

  The smaller the average particle diameter of the catalyst particles, the higher the effective electrode area where the electrochemical reaction proceeds, which is preferable because the oxygen reduction activity is also high, but in reality the phenomenon that the oxygen reduction activity decreases if the average particle diameter is too small. Is seen. Therefore, the average particle diameter of the catalyst particles contained in the oxygen electrode side electrode catalyst layer is preferably 1.5 to 20 nm, more preferably 2 to 10 nm, and particularly preferably 2 to 5 nm.

  In the present invention, the average value of the crystallite diameters obtained from the half width of the diffraction peak of the catalyst particles in X-ray diffraction is used as the average particle diameter of the catalyst particles. As such a method, a conventional general method may be used. For example, the following method is used. The catalyst particles are analyzed by a powder X-ray diffraction Rietveld analysis program such as RIETAN-2000, and a half-value width Bhkl (radian) of a predetermined crystal plane (hkl) diffraction line is obtained from the obtained analysis result. Then, an average value Dhkl (nm) of crystallite diameters in the direction perpendicular to the (hKl) crystal plane of the catalyst particles is calculated by Scherrer's formula: Dhkl = Kλ / Bhkl cos θhkl. Here, the constant K is 0.89, λ is the X-ray wavelength (nm), and θhkl is the diffraction angle (°). For example, for cubic platinum particles, platinum alloy particles, etc., the average value of the crystallite diameters in the direction perpendicular to the (111) plane is adopted as the average particle diameter.

  In the electrode catalyst in which catalyst particles are supported on the conductive support, the supported amount of the catalyst particles is preferably 10 to 80% by mass, more preferably 30 to 70% by mass with respect to the total amount of the electrode catalyst. Good. If the loading amount exceeds 80% by mass, the degree of dispersion of the catalyst particles on the conductive carrier is lowered, and although the loading amount is increased, the improvement in power generation performance is small and the economic advantage may be lowered. On the other hand, if the supported amount is less than 10% by mass, the catalyst activity per unit mass is lowered, and a large amount of electrode catalyst is required to obtain the desired power generation performance, which is not preferable.

  The electrode catalyst layer contains a solid polymer electrolyte in addition to the electrode catalyst. The solid polymer electrolyte is not particularly limited and a known one can be used, but any member having at least high proton conductivity may be used. Specifically, perfluorocarbon polymers having sulfonic acid groups such as Nafion (registered trademark, manufactured by DuPont), Flemion (registered trademark, manufactured by Asahi Glass Co., Ltd.), Aciplex (registered trademark, manufactured by Asahi Kasei Co., Ltd.), phosphoric acid, and the like. Hydrocarbon polymer compound doped with inorganic acid such as organic / inorganic hybrid polymer partially substituted with proton conductive functional group, polymer matrix impregnated with phosphoric acid solution or sulfuric acid solution And proton conductors.

  The content of the solid polymer electrolyte in the electrode catalyst layer is preferably 10 to 70% by mass, more preferably 15 to 40% by mass, based on the total amount of the conductive carrier contained in the electrode catalyst layer. Thereby, the space | gap etc. in an electrode catalyst layer can be adjusted to a desired value.

In the electrode catalyst layer of the present invention, it is desirable that the average pore diameter (E ₁ ) of the electrode catalyst layer ( ₁ ) is smaller than the average pore diameter (E ₂ ) of the electrode catalyst layer (2). Thereby, the drainage of an electrode catalyst layer can be improved more. More preferably, the ratio between the average pore diameter (E ₁ ) of the electrode catalyst layer ( ₁ ) and the average pore diameter (E ₂ ) of the electrode catalyst layer (2) is 0.1 <E ₁ / E _2. <1, especially 0.15 <E ₁ / E ₂ <0.92. If E ₁ / E ₂ is less than 0.1, the drainage performance is improved, but the water retention is decreased and the inside of the electrode catalyst layer is easily dried, which may reduce the proton conductivity of the electrode catalyst layer. If it exceeds 1, the drainage of the electrode catalyst layer may be deteriorated.

  In the present invention, the average pore size of the electrode catalyst layer means the position of the main peak observed in the pore size distribution determined by the mercury intrusion method.

When the electrode catalyst layer has a structure of three or more layers, the average pore diameter of the other electrode catalyst layer disposed between the electrode catalyst layer (1) and the electrode catalyst layer (2) It is preferable to be between the average pore diameter (E ₁ ) of ₁ ) and the average pore diameter (E ₂ ) of the electrode catalyst layer (2), and the average pore diameter increases gradually in the thickness direction. More preferably.

In the electrode catalyst layer of the present invention, the ratio (V ₁ / V ₂ ) between the porosity (V ₁ ) of the electrode catalyst layer ( ₁ ) and the porosity (V ₂ ) of the electrode catalyst layer ( ₂ ) is: preferably _{0.15 <V 1 / V 2 <} 1, more preferably from _{0.6 <V 1 / V 2 <} 0.95. If V ₁ / V ₂ is less than 0.6, the drainage of the electrode catalyst layer is improved, but the water retention is decreased and the inside of the electrode catalyst layer is easily dried, so that the proton conductivity of the electrode catalyst layer is increased. If it exceeds 0.95, the drainage of the electrode catalyst layer may be reduced.

  The porosity of the entire electrode catalyst layer is preferably 10 to 90% by volume, more preferably 30 to 70% by volume. If the porosity is less than 10% by volume, gas diffusibility may be lowered, and if it exceeds 90% by volume, the strength may be lowered and it may be difficult to stably maintain the structure of the electrode catalyst layer. There is. In the present invention, the porosity of the electrode catalyst layer means a value calculated from the weight and density of the electrode catalyst layer constituting material filled per unit volume.

In the electrode catalyst layer, the thickness (t ₁ ) of the electrode catalyst layer ( ₁ ) and the thickness (t ₂ ) of the electrode catalyst layer (2) are 0.1 <t ₁ / t ₂ <5, preferably It is preferable that 0.15 <t ₁ / t ₂ <3. If the t ₁ / t ₂ is less than 0.1, the drainage of the electrode catalyst layer is improved, but the water retention is decreased and the inside of the electrode catalyst layer is easily dried, and the proton conductivity of the electrode catalyst layer is increased. If it exceeds 5, the drainage of the electrode catalyst layer may be reduced.

  The total thickness of the electrode catalyst layer is 1 to 50 μm, preferably 5 to 30 μm. If the thickness is less than 1 μm, not only uniform film formation is difficult, but also it may be difficult to form a laminated structure of the electrode catalyst layer according to the present invention. There is a risk of lowering. In addition, in this invention, the thickness of an electrode catalyst layer can be measured with the photograph which image | photographed the cross section of the electrode catalyst layer with the scanning electron microscope (SEM).

  As a method for producing the electrode catalyst layer of the present invention, conventionally known methods can be appropriately referred to and used.

  First, an electrocatalyst is prepared by supporting catalyst particles on an electroconductive carrier, and then the electrocatalyst and the solid polymer electrolyte are mixed with water or an alcohol solvent to form an electroconductive carrier having a predetermined average secondary particle size. An electrode catalyst ink containing is prepared. In the same manner, a plurality of electrode catalyst inks containing conductive carriers having different average secondary particle sizes are prepared. Next, a step of applying and drying each of the electrode catalyst inks prepared above on the substrate so that the obtained electrode catalyst layer is composed of at least two layers having different average secondary particle diameters of the conductive carrier. Repeat. At this time, the porosity, thickness, etc. of the obtained electrode catalyst layer can be adjusted by adjusting the addition amount, coating amount, etc. of the electroconductive carrier of the electrode catalyst ink.

  In order to support the catalyst particles on the conductive carrier, a known method such as impregnation method, liquid phase reduction support method, evaporation to dryness method, colloid adsorption method, spray pyrolysis method, reverse micelle (microemulsion method) is used. Just do it. Moreover, a commercially available electrode catalyst can be used if it uses the electroconductive support | carrier which has a predetermined primary particle diameter.

  When preparing the electrode catalyst ink by mixing the electrode catalyst and the solid polymer electrolyte with water or an alcohol solvent, it is preferable to adjust the dispersibility of the conductive carrier by adjusting the stirring time and the like. Thereby, the average secondary particle diameter of an electroconductive support | carrier, the porosity in the electrode catalyst layer obtained can be adjusted. As the stirring means, a known means such as a homogenizer, an ultrasonic dispersion device, a jet mill, a bead mill or the like may be used.

  As a base material on which the electrode catalyst ink is applied, a PTFE sheet or the like can be used in addition to the solid polymer electrolyte membrane and gas diffusion layer used in MEA. Moreover, using the solid polymer electrolyte membrane and the gas diffusion layer as a base material, an electrode catalyst layer (1) is created on the solid polymer electrolyte membrane, an electrode catalyst layer (2) is created on the gas diffusion layer, The electrode catalyst layer of the present invention can also be produced by a method of joining them by hot pressing or the like. The electrocatalyst ink can be applied onto the substrate using a known method such as a die coater method, a screen printing method, a doctor blade method, or a spray method.

  The above-described electrode catalyst layer of the present invention can suppress the disappearance of corrosion of the conductive carrier in the electrode catalyst layer, the flooding phenomenon, and the like by improving drainage. Therefore, according to the electrode catalyst layer, it is possible to provide a fuel cell membrane-electrode assembly having excellent durability.

  A second aspect of the present invention is a fuel cell membrane-electrode assembly (also simply referred to as “MEA”) using the above-described electrode catalyst layer. The configuration of the MEA is not particularly limited except that the first electrode catalyst layer of the present invention is used, and is the same as a conventionally known MEA.

  The MEA has a configuration in which, for example, an oxygen electrode-side electrode catalyst layer and a fuel electrode-side electrode catalyst layer are arranged to face both surfaces of a solid polymer electrolyte membrane, and further a gas diffusion layer is sandwiched between them. Examples of the membrane-electrode assembly for a battery include a configuration in which at least one of the oxygen electrode side electrode catalyst layer and the fuel electrode side electrode catalyst layer is the first electrode catalyst layer of the present invention. Moisture in the electrode catalyst layer is promoted to move in the direction in which the average secondary particle diameter of the conductive carrier is large. Moreover, it is desirable to drain the water in the electrode catalyst layer to the outside through the gas diffusion layer. Therefore, in the MEA, the electrode catalyst layer (1) of the first electrode catalyst layer of the present invention and the solid polymer electrolyte membrane are preferably arranged in contact with each other. Thereby, the water | moisture content in an electrode catalyst layer can be discharged | emitted out of the system, and it can be set as MEA excellent in durability.

  In the MEA, the first electrode catalyst layer of the present invention may be used for either one of the fuel electrode side electrode catalyst layer and the oxygen electrode side electrode catalyst layer. It is preferably used at least for the oxygen electrode side electrode catalyst layer that tends to cause oxidization, and more preferably used for both the fuel electrode side electrode catalyst layer and the air electrode side electrode catalyst layer.

  The solid polymer electrolyte membrane used in the MEA of the present invention is not particularly limited, and examples thereof include a membrane made of the same solid polymer electrolyte as that used for the electrode catalyst layer. In addition, various Nafion (registered trademark of DuPont) manufactured by DuPont and perfluorosulfonic acid membranes represented by Flemion, ion exchange resins manufactured by Dow Chemical, ethylene-tetrafluoroethylene copolymer resin membrane, trifluoro Fluoropolymer electrolytes such as resin membranes based on styrene, hydrocarbon resin membranes with sulfonic acid groups, and other commonly available solid polymer electrolyte membranes and polymer microporous membranes A membrane impregnated with a liquid electrolyte, a membrane in which a porous body is filled with a polymer electrolyte, or the like may be used. The solid polymer electrolyte used for the solid polymer electrolyte membrane and the solid polymer electrolyte used for each electrode catalyst layer may be the same or different, but each electrode catalyst layer and the solid polymer electrolyte From the viewpoint of improving the adhesion to the film, it is preferable to use the same one.

  The thickness of the solid polymer electrolyte membrane may be appropriately determined in consideration of the properties of the obtained MEA, but is preferably 5 to 300 μm, more preferably 10 to 200 μm, and particularly preferably 15 to 150 μm. From the viewpoint of strength during film formation and durability during MEA operation, it is preferably 5 μm or more, and from the viewpoint of output characteristics during MEA operation, it is preferably 300 μm or less.

  Next, the gas diffusion layer used in the MEA of the present invention is not particularly limited, and a sheet-like material having conductivity and porosity such as a carbon woven fabric, a paper-like paper body, a felt, and a nonwoven fabric is used as a base material. And what to do. The thickness of the substrate may be appropriately determined in consideration of the characteristics of the obtained gas diffusion layer, but may be about 50 to 450 μm. If the thickness is less than 50 μm, sufficient mechanical strength or the like may not be obtained, and if it exceeds 450 μm, the distance through which gas or water permeates is undesirably increased.

  The gas diffusion layer preferably contains a water repellent in the base material in order to further improve water repellency and prevent a flooding phenomenon. Although it does not specifically limit as said water repellent, It is fluorine-type, such as a polytetrafluoroethylene (PTFE), a polyvinylidene fluoride (PVDF), a polyhexafluoropropylene, a tetrafluoroethylene-hexafluoropropylene copolymer (FEP). Examples thereof include polymer materials, polypropylene, and polyethylene.

  Moreover, in order to improve water repellency more, the said gas diffusion layer may have a carbon particle layer which consists of an aggregate | assembly of the carbon particle containing a water repellent on the said base material.

  The carbon particles are not particularly limited, and may be conventional ones such as carbon black, graphite, and expanded graphite. Of these, carbon blacks such as oil furnace black, channel black, lamp black, thermal black, and acetylene black are preferred because of their excellent electron conductivity and large specific surface area.

  The particle size of the carbon particles is preferably about 10 to 100 nm. Thereby, while being able to obtain the high drainage property by capillary force, it becomes possible to improve contact property with an electrode catalyst layer.

  Examples of the water repellent used for the carbon particle layer include the same water repellents as those described above used for the substrate. Of these, fluorine-based polymer materials are preferably used because of their excellent water repellency and corrosion resistance during electrode reaction.

  In the carbon particle layer, the mixing ratio between the carbon particles and the water repellent may be insufficient to obtain the water repellency as expected when the carbon particles are too much. There is a risk that it will not be obtained. Considering these, the mixing ratio of the carbon particles and the water repellent in the carbon particle layer is preferably about 90:10 to 40:60 in terms of mass ratio.

  The thickness of the carbon particle layer may be appropriately determined in consideration of the water repellency of the obtained gas diffusion layer.

  As a method for producing the MEA of the present invention, an electrocatalyst layer is prepared on both sides of a solid polymer electrolyte membrane, and this is used by appropriately referring to a conventionally known method such as hot pressing after sandwiching the electrode catalyst layer with a gas diffusion layer. be able to. When an electrode catalyst layer is formed on a substrate such as a PTFE sheet, the solid polymer electrolyte membrane is sandwiched by the PTFE sheet on which the electrode catalyst layer is formed so that the electrode catalyst layer is on the inside. Then, after hot pressing, the PTFE sheet is peeled off, and the MEA can be produced by a method of sandwiching the obtained joined body with a gas diffusion layer.

  Hot pressing is preferably performed at 110 to 170 ° C. and a pressing pressure of 1 to 5 MPa with respect to the electrode surface. Thereby, the bondability between the solid polymer electrolyte membrane and the electrode catalyst layer can be enhanced.

  When a water repellent is contained in the gas diffusion layer used for MEA, a general water repellent treatment method may be used. For example, after immersing the base material used for a gas diffusion layer in the dispersion liquid of a water repellent agent, the method of heat-drying with oven etc. is mentioned.

  When forming a carbon particle layer on a substrate in a gas diffusion layer, the carbon particles, water repellent, etc. are in a solvent such as water, alcohol solvents such as perfluorobenzene, dichloropentafluoropropane, methanol, ethanol, etc. A slurry is prepared by dispersing in a slurry, and the slurry is applied on a substrate and dried, or the slurry is dried and pulverized to form a powder, and this is applied to the gas diffusion layer. Use it. Then, it is preferable to heat-process at about 250-400 degreeC using a muffle furnace or a baking furnace.

  The MEA of the present invention described above can maintain high power generation performance over a long period of time by using the first electrode catalyst layer of the present invention with improved drainage. Therefore, it becomes possible to provide a fuel cell excellent in durability and power generation performance by using the MEA in a fuel cell. The type of the fuel cell is not particularly limited. In the above description, the polymer electrolyte fuel cell has been described as an example, but in addition, there are alkaline fuel cells, phosphoric acid fuel cells, and the like. Can be mentioned. Among these, a polymer electrolyte fuel cell is preferable because it is small in size, and can achieve high density and high output. The fuel cell is useful as a stationary power source in addition to a power source for a moving body such as a vehicle in which a mounting space is limited.

  The configuration of the fuel cell is not particularly limited, and a conventionally known technique may be used as appropriate. Generally, the fuel cell has a structure in which an MEA is sandwiched between separators.

  FIG. 2 is a schematic cross-sectional view showing a preferred example of the single cell configuration of the fuel cell of the present invention. FIG. 3 is a perspective view for explaining a preferred example of a fuel cell stack configuration in which a plurality of single cells of FIG. 2 are stacked.

  In FIG. 2, the basic structure of the unit cell 201 of the solid polymer fuel cell 200 is a fuel comprising a fuel electrode side electrode catalyst layer 220a and a fuel electrode side gas diffusion layer 230a on both sides of the solid polymer electrolyte membrane 210. And an oxygen electrode composed of an oxygen electrode side electrode catalyst layer 220b and an oxygen electrode side gas diffusion layer 230b. The MEA 240 is disposed opposite to each other, and the MEA 240 is further connected to the fuel electrode side separator 250a and It is sandwiched between oxygen electrode side separators 250b. In addition, the fuel gas and the oxidant gas supplied to the MEA 240 are plural on the surface facing the fuel electrode side electrode catalyst layer 220a and the oxygen electrode side electrode catalyst layer 220b on the fuel electrode side separator 250a and the oxygen electrode side separator 250b. The fuel gas is supplied through a fuel gas flow path (supply groove) 251a and an oxidant gas flow path (supply groove) 251b provided in places.

  In order to use the single cell 201 for the fuel cell (stack) 200, a single cell 201 or a stack in which two or more single cells 201 are stacked (stacked stack) is further added to both sides (both ends) of the single cell 201 or the stacked stack. ) To a pair of end plates, that is, a fuel electrode side end plate 70 and an oxygen electrode side end plate 80 (see FIG. 3).

  More specifically, as shown in FIGS. 2 and 3, the configuration of the fuel cell stack 200 includes a stack unit 20 in which a plurality of fuel cell single cells 201 are stacked, and is used as a power source. Applications of the power source include, for example, stationary devices, consumer portable devices such as mobile phones, emergency devices, outdoor devices such as leisure and construction power sources, and mobile objects such as automobiles with limited mounting space. In particular, the mobile power supply is preferably applied because a high output voltage is required after a relatively long period of shutdown.

  The fuel cell unit cell 201 has a structure that can exhibit good durability when a stack is formed, and the fuel cell stack 200 has good durability.

  On both sides of the stack part 20, current collecting plates 30, 40, insulating plates 50, 60 and end plates 70, 80 are arranged. The current collecting plates 30 and 40 are made of a gas impermeable conductive member such as dense carbon or copper plate, and are provided with output terminals 35 and 45 for outputting electromotive force generated in the stack portion 20. . The insulating plates 50 and 60 are formed from an insulating member such as rubber or resin.

  The end plates 70 and 80 are formed of a material having rigidity, for example, a metal material such as steel. The end plates 70 and 80 are provided with a fuel gas inlet 71, a fuel gas outlet 72, and an oxidant gas inlet 74 in order to circulate fuel gas (for example, hydrogen), oxidant gas (for example, oxygen), and cooling water. And an oxidant gas outlet 75, a cooling water inlet 77, and a cooling water outlet 78.

  Through holes through which the tie rods 90 are inserted are arranged at the four corners of the stack unit 20, current collecting plates 30 and 40, insulating plates 50 and 60, and end plates 70 and 80. The tie rod 90 is screwed with a nut (not shown) to a male screw portion formed at an end portion thereof, and the inside of the fuel cell stack 200 (stack portion 20) is fastened by the end plates 70 and 80. The load for forming the stack acts in the stacking direction of the fuel cell single cells 201 (MEA 240) to hold the fuel cell single cells 201 in a pressed state.

  The tie rod 90 is formed of a material having rigidity, for example, a metal material such as steel, and has an insulating surface portion to prevent an electrical short circuit between the fuel cell single cells 201. The number of tie rods 90 installed is not limited to four (four corners). The fastening mechanism of the tie rod 90 is not limited to screwing, and other means can be applied.

  As described above, the fuel cell unit cell 201 preferably includes the MEA 240, the separators 250a and 250b, and the gasket 260. The MEA 240 includes an electrolyte membrane 210, a fuel electrode side electrode (catalyst layer 220a and gas diffusion layer 230a) and an oxygen electrode side electrode (catalyst layer 220b and gas diffusion layer 230b) arranged with the electrolyte membrane 210 interposed therebetween. Separator 250a, 250b is arrange | positioned on the outer surface of MEA240. The separator 250 a has a groove portion that constitutes a flow path for circulating fuel gas, and is connected to a fuel gas inlet 71 and a fuel gas outlet 72 arranged in the end plate 70. The separator 250 b has a groove portion that constitutes a flow path 251 b for circulating the oxidant gas, and is connected to the oxidant gas introduction port 74 and the oxidant gas discharge port 75 arranged in the end plate 80.

  The separators 250a and 250b have flow paths (not shown) for circulating cooling water, and are connected to a cooling water inlet 77 and a cooling water outlet 78 arranged in the end plates 70 and 80. Has been.

  Next, the gasket 260 is a sealing member disposed so as to surround the outer periphery of the electrode located on the surface of the MEA 240, and is fixed to the outer surface of the electrolyte membrane 210 of the MEA 240 via an adhesive layer (not shown). You may have the structure which is. The gasket 260 has a function of ensuring a sealing property between the separator and the MEA. Note that the adhesive layer used as necessary preferably corresponds to the shape of the gasket 260 and is arranged in a frame shape on the entire peripheral edge of the electrolyte membrane in consideration of securing adhesiveness.

  As described above, it is possible to provide a fuel cell that can exhibit good durability when the fuel cell stack 200 is formed, and a fuel cell stack having good durability.

  Further, the fastening mechanism by the end plates 70 and 80 of the fuel cell stack 200 is not limited to the form using the tie rod 90 extending the inside, and a tension rod (not shown) extending the outside can also be used. is there.

  In the fuel cell (stack) 200 of the present invention, in order to improve the drainage of the electrode catalyst layers 220a and 220b included in the MEA 240 and to exhibit high power generation performance over a long period of time, the end plate 70, It is desirable to properly adjust the fastening pressure applied to the electrodes in MEA 240 by 80 fastenings.

That is, in the fuel cell (stack) 200 of the present invention, the fastening pressure applied to the electrode in the MEA 240 by the fastening is preferably 3 to 9 kgf / cm ² (0.3 to 0.9 Nm) per unit area of the electrode. It is good to do. The MEA 240 that can be used here is not particularly limited, and a conventionally known MEA can be appropriately used. This is because even when an existing MEA is used, drainage of the electrode catalyst layer included in the MEA can be improved and high power generation performance can be exhibited over a long period of time. It is preferable to use the fuel cell electrode catalyst layer of the present invention in which the average secondary particle diameter of the conductive carrier increases in the thickness direction as described above. In particular, the fuel cell electrode catalyst layer of the present invention is more preferably arranged so that the average secondary particle diameter of the conductive carrier increases from the electrolyte membrane side toward the gas diffusion layer side.

By setting the fastening pressure applied to the electrodes in the MEA 240 to 3 kgf / cm ² or more (0.3 Nm or more), sufficient contact between the solid polymer electrolyte membrane 210, the electrodes (220 + 230), and the separators 250a and 250b is sufficient. It is possible to ensure high power generation performance. Further, by making the fastening pressure 9 kgf / cm ² or less (0.9 Nm or less), the drainage of the electrode catalyst layer can be improved, and the constituent materials of the gas diffusion layers 230a and 230b and the separators 250a and 250b It is possible to prevent the solid polymer electrolyte membrane 210 from being damaged by the above.

  When the solid polymer electrolyte membrane 210 is broken, the electrode catalyst layers 220a and 220b facing each other come into contact with each other to generate a micro short circuit. In such a region where a short circuit occurs, heat is generated due to excessive current flowing, and the solid polymer electrolyte contained in the solid polymer electrolyte membrane 210, the electrode catalyst layers 220a, 220b, etc. is deteriorated, and the fuel cell The power generation performance is reduced.

  In the fuel cell 200 of the present invention, the electrode means a part including the electrode catalyst layers 220a and 220b and the gas diffusion layers 230a and 230b. The fastening pressure applied to the electrode by the fastening is set to a predetermined pressure per unit area of the electrode, but it is preferable to set a predetermined pressure per unit area in each electrode of the oxygen electrode and the fuel electrode.

  Furthermore, in the present invention, in the electrode catalyst layers 220a and 220b and the gas diffusion layers 230a and 230b, the operating conditions of the fuel cell 200 and the fastening applied to the electrodes (220 and 230) by the clamping (fastening) of the end plates 70 and 80 are performed. It has been found that the air gap changes, and the water movement route such as the gas diffusion route, the water generated by the fuel cell reaction, and the humidified water when supplying the humidified gas changes. Therefore, as the operating conditions of the fuel cell 200 change, in order to stably exhibit high power generation performance over a long period while maintaining high drainage, the electrodes are clamped (fastened) between the end plates 70 and 80. It is desirable to further optimize the fastening pressure applied to the fuel cell according to the operating conditions, particularly the relative humidity of the supply gas supplied to the fuel cell (stack) 200 from the outside.

That is, when the relative humidity of the fuel gas and / or oxidant gas supplied to the fuel cell (stack) 200 is less than 30%, the fastening pressure applied to the electrode in the MEA 240 is set to 7 kgf / unit per unit area of the electrode. preferably with cm ² or more 9 kgf / cm ² or less (0.7 Nm or more 0.9Nm less).

When the relative humidity of the fuel gas and / or the oxidant gas supplied to the fuel cell (stack) 200 is 30% or more and less than 50%, the fastening pressure is 5 kgf / cm ² or more per unit area of the electrode. It is preferable to be less than 7 kgf / cm ² (0.5 Nm or more and less than 0.7 Nm).

Further, when the relative humidity of the fuel gas and / or oxidant gas supplied to the fuel cell (stack) 200 is 50% or more, the fastening pressure is set to 3 kgf / cm ² or more and 5 kgf / cm ² per unit area of the electrode. ^It is preferable to be less than ² (0.3 Nm or more and less than 0.5 Nm).

  In order to adjust the fastening pressure applied to the electrode in the MEA 240 as described above, it is preferable to adjust the fastening pressure in accordance with the relative humidity of the fuel gas and / or the oxidant gas. In the case where the relative humidity differs between the fuel gas and the oxidant gas, the water movement path such as humidified water at the time of supplying the humidified gas is particularly easy to change. Thereby, high drainage property and power generation performance can be more stably exhibited (see Table 4 of Example 11 and FIGS. 4 to 5 described later).

  In the fuel cell 200 of the present invention, when the humidity of the gas supplied to the fuel cell stack 200 varies depending on operating conditions, the relative humidity of the fuel gas and / or oxidant gas supplied from the outside is set as described above. In addition, it is desirable to adjust the pressure applied to the MEA 240 by fastening the end plates 70 and 80. At that time, the single cell 201 (or stacked stack 20) is fastened in accordance with a signal obtained by detecting the relative humidity of the fuel gas and / or the oxidant gas before being supplied to the fuel cell stack 200. A method of adjusting the fastening pressure applied to the MEA 240 by variably moving the end plates 70 and 80 to be used may be used.

  The relative humidity of the supply gas (fuel gas, oxidant gas) may be measured (detected) before being supplied into the fuel cell stack 200. However, the separator 250a of each single cell 201 in the fuel cell stack 200 may be used. , 250b may be performed before being supplied to the gas flow paths 251a and 251b. That is, the supply gas is not particularly limited as long as it is before being used for the power generation reaction in the fuel cell 200. However, when the supply gas (fuel gas, oxidant gas) is humidified and then supplied into the fuel cell (stack) 200, the relative humidity after humidification is used. The relative humidity of these supply gases can be measured (detected) using a humidity measuring device such as a humidity sensor.

  Further, when the humidity of the fuel gas and / or the oxidant gas supplied to the fuel cell (stack) 200 is constant, the fastening pressure by the end plates 70 and 80 is adjusted according to the humidity of the gas, and the fuel cell. Can be assembled.

  The fuel electrode side separator 250a used in the fuel cell (stack) 200 of the present invention is a fuel gas flow for supplying fuel gas to the fuel electrode side electrode catalyst layer 220a on the surface facing the fuel electrode side electrode catalyst layer 220a. As long as it has at least the path 251a, a conventionally known one can be used without particular limitation. The fuel gas inlet 71, fuel gas outlet 72, oxidant gas inlet 74, and oxidant gas outlet described above are disposed at both ends in the lateral direction within the plane of the fuel electrode side separator 220 a and located at the outer edge. 75, an inlet side fuel gas communication hole, an inlet side oxidant gas communication hole, an inlet side cooling medium communication hole, an outlet side cooling medium communication hole, so as to be connected to the cooling water introduction port 77 and the cooling water discharge port 78, respectively. An outlet side fuel gas communication hole and an outlet side oxidant gas communication hole may be formed, and further a communication hole for the tie rod 90 may be formed.

  In addition, the oxygen electrode side separator 250b has at least an oxidant gas flow path 251b for supplying an oxidant gas to the oxygen electrode side electrode catalyst layer 220b on the surface facing the oxygen electrode side electrode catalyst layer 220b. For example, conventionally known ones can be used without particular limitation. The fuel gas inlet 71, the fuel gas outlet 72, the oxidant gas inlet 74, and the oxidant gas outlet described above are also provided at both ends in the lateral direction within the plane of the oxygen electrode separator 250b and located at the outer edge. 75, an inlet side fuel gas communication hole, an inlet side oxidant gas communication hole, an inlet side cooling medium communication hole, an outlet side cooling medium communication hole, so as to be connected to the cooling water introduction port 77 and the cooling water discharge port 78, respectively. An outlet side fuel gas communication hole and an outlet side oxidant gas communication hole may be formed, and further a communication hole for the tie rod 90 may be formed.

  The shapes of the fuel gas channel 251a and the oxidant gas channel 251b formed in each separator 250a, 250b are not particularly limited, but are within a predetermined range from the viewpoint of improving the drainage and power generation performance of the fuel cell (stack) 200. It is preferable to be inside.

  The groove width (indicated by W in FIG. 2) of the fuel gas channel 251a and the oxidant gas channel 251b formed in each separator 250a, 250b is preferably 0.5 to 1.5 mm. If the groove width W of the gas flow paths 251a and 251b is less than 0.5 mm, the flow of fuel gas, oxidant gas and moisture may be reduced, leading to a decrease in drainage and power generation performance. When the groove width W of the gas flow paths 251a and 251b exceeds 1.5 mm, the constituent materials of the electrodes such as the gas diffusion layers 230a and 230b fall into the flow path, and the flow of fuel gas, oxidant gas, and moisture There is a risk that drainage and power generation performance will be reduced.

  Further, the groove depth (indicated by H in FIG. 2) of the fuel gas channel 251a and the oxidant gas channel 251b formed in each separator 250a, 250b is preferably 0.1 to 1.2 mm. Is good. When the groove depth H of the gas flow paths 251a and 251b is less than 0.1 mm, the constituent materials of the electrodes such as the gas diffusion layers 230a and 230b fall into the flow path, and the flow of fuel gas, oxidant gas, and moisture is reduced. This may reduce the drainage performance and power generation performance. Moreover, if the groove depth H of the gas flow paths 251a and 251b exceeds 1.2 mm, the strength of the separator 250 may be reduced. In such a case, it may be possible to secure the strength by increasing the thickness of the separator. However, when the single cells 201 are stacked, the size of the stack (stack portion 20) inside the fuel cell 200 may increase. Therefore, it is not desirable.

  Separators 250a and 250b used on the fuel electrode side and oxygen electrode side include dense carbon graphite, carbon such as carbon plate, metal such as stainless steel, ceramic, glass, inorganic material such as silicon, epoxy resin, polyimide resin Any organic material such as polyethylene terephthalate (PET) or organic / inorganic composite material such as epoxy resin containing glass fiber can be used without limitation.

  The thickness and size of the separator, the shape of the gas flow path, and the like are not particularly limited, and may be appropriately determined in consideration of the output characteristics of the obtained fuel cell. As the separator, a fuel electrode side separator between adjacent single cells and an oxygen electrode side separator (bipolar separator) may be used.

  In the fuel cell of the present invention, the pressure applied to the MEA 240 by fastening the end plates 70 and 80 is not particularly limited, but the single cell 201 (or the stacked stack 20) is inserted into the fuel electrode side end plate from both sides in the thickness direction. 70 and the oxygen electrode side end plate 80, and pressure can be applied by fastening the tie rod 90 using fastening means such as fastening bolts. Further, various conventionally known fastening pressure adjusting means for controlling the fastening torque of the fastening bolt by a method of moving a stepping motor (pulse motor) or the like so that the end plates 70 and 80 can be variably moved in the thickness direction. , And the fastening pressure can be adjusted (controlled) in a timely manner in response to changes in the relative humidity of the supply gas.

  In order to sandwich both sides of the single cell 201 (or the stacked stack 20) with the end plates 70, 80, both sides of the single cell 201 (or the stacked stack 20) are connected to the current collecting plates 30, 40 and the insulating plates 50, 60. It is sufficient to use a method in which the tie rod 90 is fixed (fastened) from both ends with fastening bolts. However, the present invention is not limited to the above method, and may be performed by appropriately referring to conventionally known techniques for assembling the fuel cell.

  The end plates 70 and 80 can be used without limitation as long as they are conventionally known. The end plates 70 and 80 also have the above-described fuel gas inlet 71, fuel gas outlet 72, oxidant gas inlet 74, oxidant gas outlet 75, cooling water inlet 77, and cooling water outlet 78. The inlet side fuel gas communication hole, the inlet side oxidant gas communication hole, the inlet side cooling medium communication hole, the outlet side cooling medium communication hole, the outlet side fuel gas communication hole, and the outlet side oxidant gas. A communication hole may be formed, and further, a communication hole for the tie rod 90 may be formed.

  Further, in the present invention, two or more single cells 201 are laminated so that the obtained fuel cell stack 200 has a desired power generation amount, and a pair of end plates are provided on both sides of the obtained laminated stack (stack part 20). You may have the structure clamped by 70,80.

  Hereinafter, the present invention will be described more specifically with reference to examples. In addition, this invention is not limited only to the following Example.

Example 1
1. Preparation of electrode catalyst layer (1) To a glass container in a water bath set to be kept at 20 ° C., ultrapure water, a solid polymer electrolyte solution (Nafion solution DE520 manufactured by DuPont, electrolyte content 5% by weight), Next, ethylene glycol (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent) was gradually added dropwise and mixed and stirred for 10 minutes using a homogenizer. Next, an electrode catalyst (TEC10E50E manufactured by Tanaka Kikinzoku Kogyo Co., Ltd .: 50% by weight of platinum supported on Ketjen Black, average platinum particle size of 3 nm) was added to this solution, and the mixture was stirred for 3 hours to obtain an electrode catalyst ink 1. . The electrode catalyst ink 1 was applied to both surfaces of a solid polymer electrolyte membrane (Nafion (registered trademark) NR-111, size 100 mm × 100 mm, thickness 25 μm) by a die coater method, and air-dried to form an electrode catalyst layer (1). Got. Each electrode catalyst layer (1) on the fuel electrode side and oxygen electrode side thus obtained had an area of 50 mm × 50 mm, a Pt support amount of 0.25 mg / cm ² , a thickness t ₁ = 6 μm, and an average pore diameter E ₁ = 0. 045 μm, porosity V ₁ = 45%, average primary particle diameter D ₁ ′ = 20 nm of ketjen black, average secondary particle diameter D ₁ = 0.10 μm of ketjen black, solid polymer electrolyte and ketjen black The weight ratio (solid polymer electrolyte / Ketjen black) was 0.85.

2. Preparation of gas diffusion layer Carbon paper (TGP-H-060 manufactured by Toray Industries, Inc., thickness 180 μm) was punched into a 55 × 55 mm square, and then an aqueous dispersion solution of PTFE fluororesin (D1, PTFE60 manufactured by Daikin Industries, Ltd.) (Mass% content) was immersed in a solution diluted with pure water to a predetermined concentration for 2 minutes, then dried in an oven at 60 ° C. for 10 minutes, and the water-repellent treatment was performed on the carbon paper to obtain a gas diffusion layer. It was. At this time, the PTFE content in the carbon paper was 25% by mass. Next, the gas diffusion layer was heat-treated at 350 ° C. for 5 minutes in an inert gas atmosphere.

3. Preparation of electrode catalyst layer (2) To a glass container in a water bath set to be kept at 20 ° C., ultrapure water, a solid polymer electrolyte solution (DuPont Nafion solution DE520, electrolyte content 5 wt%), Next, ethylene glycol (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent) was gradually added dropwise and mixed and stirred for 10 minutes using a homogenizer. Then, an electrode catalyst (TEC10E50E manufactured by Tanaka Kikinzoku Kogyo Co., Ltd .: 50% by weight of platinum supported on Ketjen Black, average platinum particle size of 3 nm) was added to this solution, and the mixture was stirred for 2 hours to obtain an electrode catalyst ink 2. . This electrode catalyst ink 2 was applied onto the gas diffusion layer produced above by a die coater method and air-dried to prepare two electrode catalyst layers (2) for the fuel electrode side and the oxygen electrode side. The obtained electrode catalyst layers (2) on the fuel electrode side and oxygen electrode side each have an area of 50 mm × 50 mm, a Pt loading amount of 0.25 mg / cm ² , a thickness t ₂ = 9 μm, and an average pore diameter E ₂ = 0.058 μm, porosity V ₂ = 55%, ketjen black average primary particle diameter D ₂ ′ = 20 nm, ketjen black average secondary particle diameter D ₂ = 0.15 μm, solid polymer electrolyte and ketjen black The ratio by weight (solid polymer electrolyte / Ketjen black) was 0.85.

4). Assembly of MEA and single cell A solid polymer electrolyte membrane formed on both sides of a fuel electrode side electrode catalyst layer (1) and an oxygen electrode side electrode catalyst layer (1), and an electrode catalyst layer (2) on a gas diffusion layer It clamped using the formed 2 sheets. Thereafter, a membrane-electrode assembly was produced by hot pressing for 3 minutes under the conditions of 120 ° C. and 20 kgf / cm ² ( ² Nm), and this was made into a graphite separator (the groove width of the fuel gas and oxidant gas channels ( W) 1.0 mm, the groove depth (H) of the fuel gas and oxidant gas flow paths (H) 1.0 mm), and further sandwiched by a gold-plated stainless steel current collector plate, and the fastening pressure applied to the electrodes ( The cell fastening force is hereinafter referred to as “cell fastening force” as 4.5 kgf / cm ² (0.45 Nm) per unit area of the electrode.

  Durability evaluation of the single cell for evaluation was performed according to the following procedure by dividing durability evaluation by continuous operation and durability evaluation by starting and stopping.

(1) Endurance evaluation by continuous operation Atmospheric pressure, cell temperature of 70 ° C., hydrogen gas as fuel gas and air gas as oxidant gas, both gases were humidified at 60 ° C. and supplied to the single cell for evaluation. For both gases, the cell outlet pressure is atmospheric pressure, hydrogen gas has a dew point of 60 ° C. and a relative humidity of 64% and a supply gas flow rate of 0.261 L / min, and air gas has a dew point of 60 ° C. and a relative humidity of 64% and a supply gas flow rate of 0. .625 L / min. Under this condition, the cell voltage (initial cell voltage) at a current density of 1.0 A / cm ² was measured. Next, continuous operation is performed for 100 hours under these conditions, and the retention rate of the cell voltage after continuous operation with respect to the initial cell voltage before continuous operation {(cell voltage after continuous operation for 100 hours / initial cell voltage) '100 (%) } Was evaluated as durability. The initial cell voltage was 0.620 V, and the cell voltage holding ratio was 98.1%.

(2) Endurance evaluation by starting and stopping The initial cell voltage was measured under the same test conditions as in (1) above. After 1 hour of continuous power generation, power generation was terminated, and at the end both the fuel electrode and oxygen electrode were converted to a single cell. The gas supply was stopped, the single cell was left for 10 minutes, and the continuous operation was performed again for 1 hour under the same conditions. This operation is performed as a start / stop condition, and is performed 3,000 times. The retention ratio of the cell voltage after start / stop with respect to the initial cell voltage before the start / stop test {(cell voltage after 3,000 start / stop / initial cell voltage) ) '100 (%)} was evaluated as durability. The initial cell voltage was 0.620 V, and the cell voltage holding ratio was 96.9%.

  In addition, a structure and a result are put together in Table 1 and Table 2, and are shown.

(Example 2)
1. Preparation of electrode catalyst layer (1) To a glass container in a water bath set to be kept at 20 ° C., ultrapure water, a solid polymer electrolyte solution (Nafion solution DE520 manufactured by DuPont, electrolyte content 5% by weight), Next, ethylene glycol (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent) was gradually added dropwise and mixed and stirred for 10 minutes using a homogenizer. Next, an electrode catalyst (TEC10E50E manufactured by Tanaka Kikinzoku Kogyo Co., Ltd .: 50% by weight of platinum supported on Ketjen Black, average platinum particle size of 3 nm) was added to this solution, and the mixture was stirred for 3 hours to obtain an electrode catalyst ink 1. . The electrode catalyst ink 1 was applied to both surfaces of a solid polymer electrolyte membrane (Nafion (registered trademark) NR-111, size 100 mm × 100 mm, thickness 25 μm) by a die coater method, and air-dried to form an electrode catalyst layer (1). Got. The obtained electrode catalyst layer (1) on the fuel electrode side and oxygen electrode side has an area of 50 mm × 50 mm, a Pt support amount of 0.10 mg / cm ² , a thickness t ₁ = 2.5 μm, and an average pore diameter E ₁ = 0. 0.04 μm, porosity V ₁ = 45%, average primary particle diameter D ₁ ′ = 20 nm of ketjen black, average secondary particle diameter D ₁ = 0.10 μm of ketjen black, solid polymer electrolyte and ketjen black The weight ratio (solid polymer electrolyte / Ketjen black) was 0.85.

2. Production of Gas Diffusion Electrode Same as Example 1.

3. Preparation of electrode catalyst layer (2) To a glass container in a water bath set to be kept at 20 ° C., ultrapure water, a solid polymer electrolyte solution (DuPont Nafion solution DE520, electrolyte content 5 wt%), Next, ethylene glycol (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent) was gradually added dropwise and mixed and stirred for 10 minutes using a homogenizer. Then, an electrode catalyst (TEC10E50E manufactured by Tanaka Kikinzoku Kogyo Co., Ltd .: 50% by weight of platinum supported on Ketjen Black, average platinum particle size of 3 nm) was added to this solution, and the mixture was stirred for 2 hours to obtain an electrode catalyst ink 2. . This electrode catalyst ink 2 was applied onto the gas diffusion layer produced above by a die coater method and air-dried to prepare two electrode catalyst layers (2) for the fuel electrode side and the oxygen electrode side. The obtained electrode catalyst layer (2) on the fuel electrode side and oxygen electrode side each had an area of 50 mm × 50 mm, a Pt loading of 0.40 mg / cm ² , a thickness t ₂ = 14 μm, and an average pore diameter E ₂ = 0. 0.058 μm, porosity V ₂ = 55%, average primary particle diameter D ₂ ′ = 20 nm of ketjen black, average secondary particle diameter D ₂ = 0.15 μm of ketjen black, solid polymer electrolyte and ketjen black The weight ratio (solid polymer electrolyte / Ketjen black) was 0.85.

4). Assembly of MEA and Single Cell A membrane-electrode assembly was produced in the same manner as in Example 1, and a single cell for evaluation was prepared in the same manner as in Example 1.

  The durability of the evaluation single cell was evaluated in the same manner as in Example 1. The initial cell voltage for continuous operation durability evaluation was 0.618V, and the cell voltage holding ratio was 99.5%. On the other hand, the initial cell voltage in the start / stop durability evaluation was 0.618 V, and the cell voltage holding ratio was 98.9%. The configuration and results are summarized in Tables 1 and 2.

(Example 3)
1. Preparation of electrode catalyst layer (1) To a glass container in a water bath set to be kept at 20 ° C., ultrapure water, a solid polymer electrolyte solution (Nafion solution DE520 manufactured by DuPont, electrolyte content 5% by weight), Next, ethylene glycol (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent) was gradually added dropwise and mixed and stirred for 10 minutes using a homogenizer. Next, an electrode catalyst (TEC10E50E manufactured by Tanaka Kikinzoku Kogyo Co., Ltd .: 50% by weight of platinum supported on Ketjen Black, average platinum particle size of 3 nm) was added to this solution, and the mixture was stirred for 3 hours to obtain an electrode catalyst ink 1. . This electrode catalyst ink 1 was applied to both surfaces of the solid polymer electrolyte membrane by a die coater method and air-dried to obtain an electrode catalyst layer (1). The obtained electrode catalyst layer (1) on the fuel electrode side and oxygen electrode side has an area of 50 mm × 50 mm, a Pt loading of 0.40 mg / cm ² , a thickness t ₁ = 10 μm, and an average pore diameter E ₁ = 0.045 μm. , Porosity V ₁ = 45%, average primary particle diameter D ₁ ′ = 20 nm of ketjen black, average secondary particle diameter D _{1 of} ketjen black = 0.10 μm, weight of solid polymer electrolyte and ketjen black The ratio (solid polymer electrolyte / ketchen black) was 0.85.

2. Preparation of Gas Diffusion Layer Same as Example 1.

3. Preparation of electrode catalyst layer (2) To a glass container in a water bath set to be kept at 20 ° C., ultrapure water, a solid polymer electrolyte solution (DuPont Nafion solution DE520, electrolyte content 5 wt%), Next, ethylene glycol (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent) was gradually added dropwise and mixed and stirred for 10 minutes using a homogenizer. Then, an electrode catalyst (TEC10E50E manufactured by Tanaka Kikinzoku Kogyo Co., Ltd .: 50% by weight of platinum supported on Ketjen Black, average platinum particle size of 3 nm) was added to this solution, and the mixture was stirred for 2 hours to obtain an electrode catalyst ink 2. . This electrode catalyst ink 2 was applied onto the gas diffusion layer produced above by a die coater method and air-dried to prepare two electrode catalyst layers (2) for the fuel electrode side and the oxygen electrode side. The obtained electrode catalyst layer (2) on the fuel electrode side and oxygen electrode side has an area of 50 mm × 50 mm, a Pt loading amount of 0.10 mg / cm ² , a thickness t ₂ = 4 μm, and an average pore diameter E ₂ = 0. 0.058 μm, porosity V ₂ = 55%, average primary particle diameter D ₂ ′ = 20 nm of ketjen black, average secondary particle diameter D ₂ = 0.15 μm of ketjen black, solid polymer electrolyte and ketjen black The weight ratio (solid polymer electrolyte / Ketjen black) was 0.85.

4). Assembly of MEA and Single Cell A membrane-electrode assembly was produced in the same manner as in Example 1, and a single cell for evaluation was prepared in the same manner as in Example 1.

  The durability of the evaluation single cell was evaluated in the same manner as in Example 1. The initial cell voltage for continuous operation durability evaluation was 0.622 V, and the cell voltage holding ratio was 97.1%. On the other hand, the initial cell voltage in the start / stop durability evaluation was 0.622 V, and the cell voltage holding ratio was 96.1%. The configuration and results are summarized in Tables 1 and 2.

Example 4
1. Preparation of electrode catalyst layer (1) To a glass container in a water bath set to be kept at 20 ° C., ultrapure water, a solid polymer electrolyte solution (Nafion solution DE520 manufactured by DuPont, electrolyte content 5% by weight), Next, ethylene glycol (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent) was gradually added dropwise and mixed and stirred for 10 minutes using a homogenizer. Next, an electrode catalyst (TEC 10E50E manufactured by Tanaka Kikinzoku Kogyo Co., Ltd .: 50% by weight of platinum supported on Ketjen Black, average platinum particle size of 3 nm) was added to this solution, and mixed and stirred for 2 hours to obtain an electrode catalyst ink 1. . The electrode catalyst ink 1 was applied to both surfaces of a solid polymer electrolyte membrane (Nafion (registered trademark) NR-111, size 100 mm × 100 mm, thickness 25 μm) by a die coater method, and air-dried to form an electrode catalyst layer (1). Got. The obtained electrode catalyst layer (1) on the fuel electrode side and oxygen electrode side had a coating area of 50 mm × 50 mm, a Pt loading of 0.40 mg / cm ² , a thickness t ₁ = 14 μm, and an average pore diameter E ₁ = 0. 058 μm, porosity V ₁ = 55%, average primary particle diameter D ₁ ′ = 20 nm of ketjen black, average secondary particle diameter D ₁ = 0.15 μm of ketjen black, solid polymer electrolyte and ketjen black The weight ratio (solid polymer electrolyte / Ketjen black) was 0.85.

2. Preparation of Gas Diffusion Layer Same as Example 1.

3. Preparation of electrode catalyst layer (2) To a glass container in a water bath set to be kept at 20 ° C., ultrapure water, a solid polymer electrolyte solution (DuPont Nafion solution DE520, electrolyte content 5 wt%), Next, ethylene glycol (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent) was gradually added dropwise and mixed and stirred for 10 minutes using a homogenizer. Next, an electrode catalyst (TEC10E50E manufactured by Tanaka Kikinzoku Kogyo Co., Ltd .: 50% by weight of platinum supported on Ketjen Black, average platinum particle size of 3 nm) was added to this solution, and the mixture was stirred for 1.5 hours. did. This electrode catalyst ink 2 was applied onto the gas diffusion layer produced above by a die coater method and air-dried to prepare two electrode catalyst layers (2) for the fuel electrode and the oxygen electrode. The obtained electrode catalyst layer (2) on the fuel electrode side and oxygen electrode side has an area of 50 mm × 50 mm, a Pt loading of 0.10 mg / cm ² , a thickness t ₂ = 6 μm, and an average pore diameter E ₂ = 0. 0.086 μm, porosity V ₂ = 63%, ketjen black average primary particle diameter D ₂ ′ = 20 nm, ketjen black average secondary particle diameter D ₂ = 0.25 μm, solid polymer electrolyte and ketjen black The weight ratio (solid polymer electrolyte / Ketjen black) was 0.85.

4). Assembly of MEA and Single Cell A membrane-electrode assembly was produced in the same manner as in Example 1, and a single cell for evaluation was prepared in the same manner as in Example 1.

  The durability of the evaluation single cell was evaluated in the same manner as in Example 1. The initial cell voltage in the continuous operation durability evaluation was 0.605 V, and the cell voltage holding ratio was 96.7%. On the other hand, the initial cell voltage in the start / stop durability evaluation was 0.605 V, and the cell voltage holding ratio was 95.9%. The configuration and results are summarized in Tables 1 and 2.

(Example 5)
1. Preparation of electrode catalyst layer (1) To a glass container in a water bath set to be kept at 20 ° C., ultrapure water, a solid polymer electrolyte solution (Nafion solution DE520 manufactured by DuPont, electrolyte content 5% by weight), Next, ethylene glycol (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent) was gradually added dropwise and mixed and stirred for 10 minutes using a homogenizer. Next, an electrode catalyst (TEC10E50E manufactured by Tanaka Kikinzoku Kogyo Co., Ltd .: 50% by weight of platinum supported on Ketjen Black, average platinum particle size of 3 nm) was added to this solution, and the mixture was stirred for 3 hours to obtain an electrode catalyst ink 1. . The electrode catalyst ink 1 was applied to both surfaces of a solid polymer electrolyte membrane (Nafion (registered trademark) NR-111, size 100 mm × 100 mm, thickness 25 μm) by a die coater method, and air-dried to form an electrode catalyst layer (1). Got. The obtained electrode catalyst layer (1) on the fuel electrode side and oxygen electrode side has a coating area of 50 mm × 50 mm, a Pt loading of 0.40 mg / cm ² , a thickness t ₁ = 10 μm, and an average pore diameter E ₁ = 0. 045 μm, porosity V ₁ = 45%, average primary particle diameter D ₁ ′ = 20 nm of ketjen black, average secondary particle diameter D ₁ = 0.10 μm of ketjen black, solid polymer electrolyte and ketjen black The weight ratio (solid polymer electrolyte / Ketjen black) was 0.85.

2. Preparation of Gas Diffusion Layer Same as Example 1.

3. Preparation of electrode catalyst layer (2) To a glass container in a water bath set to be kept at 20 ° C., ultrapure water, a solid polymer electrolyte solution (DuPont Nafion solution DE520, electrolyte content 5 wt%), Next, ethylene glycol (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent) was gradually added dropwise and mixed and stirred for 10 minutes using a homogenizer. Next, an electrode catalyst (TEC 10E50E manufactured by Tanaka Kikinzoku Kogyo Co., Ltd .: 50% by weight of platinum supported on Ketjen Black, average platinum particle size 3 nm) was added to this solution, and the mixture was stirred and stirred for 1 hour to obtain an electrode catalyst ink 2. . This electrode catalyst ink 2 was applied onto the gas diffusion layer produced above by a die coater method and air-dried to prepare two electrode catalyst layers (2) for the fuel electrode side and the oxygen electrode side. The obtained electrode catalyst layer (2) on the fuel electrode side and oxygen electrode side has an area of 50 mm × 50 mm, a Pt loading amount of 0.10 mg / cm ² , a thickness t ₂ = 8 μm, and an average pore diameter E ₂ = 0. .14 μm, porosity V ₂ = 70%, average primary particle diameter D ₂ ′ = 20 nm of ketjen black, average secondary particle diameter D ₂ = 0.40 μm of ketjen black, solid polymer electrolyte and ketjen black The weight ratio (solid polymer electrolyte / Ketjen black) was 0.85.

4). Assembly of MEA and Single Cell A membrane-electrode assembly was produced in the same manner as in Example 1, and a single cell for evaluation was prepared in the same manner as in Example 1.

  The durability of the evaluation single cell was evaluated in the same manner as in Example 1. The initial cell voltage for continuous operation durability evaluation was 0.615 V, and the cell voltage holding ratio was 99.7%. On the other hand, the initial cell voltage in the start / stop durability evaluation was 0.615 V, and the cell voltage holding ratio was 98.7%. The configuration and results are summarized in Tables 1 and 2.

(Example 6)
1. Preparation of electrode catalyst layer (1) To a glass container in a water bath set to be kept at 20 ° C., ultrapure water, a solid polymer electrolyte solution (Nafion solution DE520 manufactured by DuPont, electrolyte content 5% by weight), Next, ethylene glycol (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent) was gradually added dropwise and mixed and stirred for 10 minutes using a homogenizer. Next, an electrode catalyst (TEC10E50E manufactured by Tanaka Kikinzoku Kogyo Co., Ltd .: 50% by weight of platinum supported on Ketjen Black, average platinum particle size of 3 nm) was added to this solution, and the mixture was stirred and stirred for 1.5 hours. It was. The electrode catalyst ink 1 was applied to both surfaces of a solid polymer electrolyte membrane (Nafion (registered trademark) NR-111, size 100 mm × 100 mm, thickness 25 μm) by a die coater method, and air-dried to form an electrode catalyst layer (1). Got. The obtained electrode catalyst layer (1) on the fuel electrode side and oxygen electrode side has a coating area of 50 mm × 50 mm, a Pt loading of 0.40 mg / cm ² , a thickness t ₁ = 22 μm, and an average pore diameter E ₁ = 0. 086 μm, porosity V ₁ = 63%, ketjen black average primary particle diameter D ₁ ′ = 20 nm, ketjen black average secondary particle diameter D ₁ = 0.25 μm, solid polymer electrolyte and ketjen black The weight ratio (solid polymer electrolyte / Ketjen black) was 0.85.

2. Preparation of Gas Diffusion Layer Same as Example 1.

3. Preparation of electrode catalyst layer (2) To a glass container in a water bath set to be kept at 20 ° C., ultrapure water, a solid polymer electrolyte solution (DuPont Nafion solution DE520, electrolyte content 5 wt%), Next, ethylene glycol (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent) was gradually added dropwise and mixed and stirred for 10 minutes using a homogenizer. Next, an electrode catalyst (TEC 10E50E manufactured by Tanaka Kikinzoku Kogyo Co., Ltd .: 50% by weight of platinum supported on Ketjen Black, average platinum particle size of 3 nm) was added to this solution, and the mixture was stirred and stirred for 1 hour to obtain an electrode catalyst ink 2. . This electrode catalyst ink 2 was applied onto the gas diffusion layer produced above by a die coater method and air-dried to prepare two electrode catalyst layers (2) for the fuel electrode side and the oxygen electrode side. The obtained electrode catalyst layer (2) on the fuel electrode side and oxygen electrode side has an area of 50 mm × 50 mm, a Pt loading amount of 0.10 mg / cm ² , a thickness t ₂ = 8 μm, and an average pore diameter E ₂ = 0. .14 μm, porosity V ₂ = 70%, average primary particle diameter D ₂ ′ = 20 nm of ketjen black, average secondary particle diameter D ₂ = 0.40 μm of ketjen black, solid polymer electrolyte and ketjen black The weight ratio (solid polymer electrolyte / Ketjen black) was 0.85.

4). Assembly of MEA and Single Cell A membrane-electrode assembly was produced in the same manner as in Example 1, and a single cell for evaluation was prepared in the same manner as in Example 1.

  The durability of the evaluation single cell was evaluated in the same manner as in Example 1. The initial cell voltage for continuous operation durability evaluation was 0.592 V, and the cell voltage holding ratio was 99.2%. On the other hand, the initial cell voltage in the start / stop durability evaluation was 0.592 V, and the cell voltage holding ratio was 98.3%. The configuration and results are summarized in Tables 1 and 2.

(Example 7)
1. Preparation of electrode catalyst layer (1) To a glass container in a water bath set to be kept at 20 ° C., ultrapure water, a solid polymer electrolyte solution (Nafion solution DE520 manufactured by DuPont, electrolyte content 5% by weight), Next, ethylene glycol (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent) was gradually added dropwise and mixed and stirred for 10 minutes using a homogenizer. Next, an electrode catalyst (TEC10E50E manufactured by Tanaka Kikinzoku Kogyo Co., Ltd .: 50% by weight of platinum supported on Ketjen Black, average platinum particle size of 3 nm) was added to this solution, and the mixture was stirred for 3 hours to obtain an electrode catalyst ink 1. . The electrode catalyst ink 1 was applied to both surfaces of a solid polymer electrolyte membrane (Nafion (registered trademark) NR-111, size 100 mm × 100 mm, thickness 25 μm) by a die coater method, and air-dried to form an electrode catalyst layer (1). Got. The obtained electrode catalyst layer (1) on the fuel electrode side and oxygen electrode side has a coating area of 50 mm × 50 mm, a Pt loading of 0.40 mg / cm ² , a thickness t ₁ = 10 μm, and an average pore diameter E ₁ = 0. 045 μm, porosity V ₁ = 45%, average primary particle diameter D ₁ ′ = 20 nm of ketjen black, average secondary particle diameter D ₁ = 0.10 μm of ketjen black, solid polymer electrolyte and ketjen black The weight ratio (solid polymer electrolyte / Ketjen black) was 0.85.

2. Preparation of Gas Diffusion Layer Same as Example 1.

3. Preparation of electrode catalyst layer (2) To a glass container in a water bath set to be kept at 20 ° C., ultrapure water, a solid polymer electrolyte solution (DuPont Nafion solution DE520, electrolyte content 5 wt%), Next, ethylene glycol (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent) was gradually added dropwise and mixed and stirred for 10 minutes using a homogenizer. Next, an electrode catalyst (TEC10E50E manufactured by Tanaka Kikinzoku Co., Ltd .: 50% by weight of platinum and an average platinum particle size of 3 nm) was added to this solution, and mixed and stirred for 20 minutes to obtain an electrode catalyst ink 2. This electrode catalyst ink 2 was applied onto the gas diffusion layer produced above by a die coater method and air-dried to prepare two electrode catalyst layers (2) for the fuel electrode side and the oxygen electrode side. The obtained electrode catalyst layer (2) on the fuel electrode side and oxygen electrode side has an area of 50 mm × 50 mm, a Pt loading amount of 0.10 mg / cm ² , a thickness t ₂ = 9 μm, and an average pore diameter E ₂ = 0. 0.055 μm, porosity V ₂ = 52%, ketjen black average primary particle diameter D ₂ ′ = 20 nm, ketjen black average secondary particle diameter D ₂ = 0.75 μm, solid polymer electrolyte and ketjen black The weight ratio (solid polymer electrolyte / Ketjen black) was 0.85.

4). Assembly of MEA and Single Cell A membrane-electrode assembly was produced in the same manner as in Example 1, and a single cell for evaluation was prepared in the same manner as in Example 1.

  The durability of the evaluation single cell was evaluated in the same manner as in Example 1. The initial cell voltage for continuous operation durability evaluation was 0.611 V, and the cell voltage holding ratio was 94.1%. On the other hand, the initial cell voltage in the start / stop durability evaluation was 0.611 V, and the cell voltage holding ratio was 92.3%. The configuration and results are summarized in Tables 1 and 2.

(Example 8)
1. Preparation of electrode catalyst layer (1) To a glass container in a water bath set to be kept at 20 ° C., ultrapure water, a solid polymer electrolyte solution (Nafion solution DE520 manufactured by DuPont, electrolyte content 5% by weight), Next, ethylene glycol (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent) was gradually added dropwise and mixed and stirred for 10 minutes using a homogenizer. Next, an electrode catalyst (TEC10EA50E manufactured by Tanaka Kikinzoku Kogyo Co., Ltd .: 50% by weight of platinum supported on graphitized ketjen black, average platinum particle size 4.5 nm) is added to this solution, and the mixture is stirred for 5 hours. Catalyst ink 1 was obtained. The electrode catalyst ink 1 was applied to both surfaces of a solid polymer electrolyte membrane (Nafion (registered trademark) NR-111, size 100 mm × 100 mm, thickness 25 μm) by a die coater method, and air-dried to form an electrode catalyst layer (1). Got. The obtained electrode catalyst layer (1) on the fuel electrode side and oxygen electrode side has an area of 50 mm × 50 mm, a Pt loading amount of 0.10 mg / cm ² , a thickness t ₁ = 2 μm, and an average pore diameter E ₁ = 0.018 μm. , Porosity V ₁ = 35%, average primary particle diameter D ₁ ′ = 20 nm of ketjen black, average secondary particle diameter D ₁ = 0.045 μm of ketjen black, weight of solid polymer electrolyte and ketjen black The ratio (solid polymer electrolyte / ketchen black) was 0.85.

2. Preparation of Gas Diffusion Layer Same as Example 1.

3. Preparation of electrode catalyst layer (2) To a glass container in a water bath set to be kept at 20 ° C., ultrapure water and a polymer electrolyte solution (Nafion solution DE520 manufactured by DuPont, electrolyte content 5% by weight) were added, and then Ethylene glycol (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent) was gradually added dropwise and mixed and stirred for 10 minutes using a homogenizer. Next, an electrode catalyst (TEC 10E50E manufactured by Tanaka Kikinzoku Kogyo Co., Ltd .: 50% by weight of platinum supported on Ketjen Black, average platinum particle size of 3 nm) was added to this solution, and the mixture was stirred and stirred for 1 hour to obtain an electrode catalyst ink 2. . This electrode catalyst ink 2 was applied onto the gas diffusion layer produced above by a die coater method and air-dried to prepare two electrode catalyst layers (2) for the fuel electrode side and the oxygen electrode side. The obtained fuel electrode side and oxygen electrode side electrode catalyst layers (2) each have an area of 50 mm × 50 mm, a Pt loading of 0.40 mg / cm ² , a thickness t ₂ = 36 μm, and an average pore diameter E ₂ = 0. .14 μm, porosity V ₂ = 70%, average primary particle diameter D ₂ ′ = 20 nm of ketjen black, average secondary particle diameter D ₂ = 0.40 μm of ketjen black, solid polymer electrolyte and ketjen black The weight ratio (solid polymer electrolyte / Ketjen black) was 0.85.

4). Assembly of MEA and Single Cell A membrane-electrode assembly was produced in the same manner as in Example 1, and a single cell for evaluation was prepared in the same manner as in Example 1.

  The durability of the evaluation single cell was evaluated in the same manner as in Example 1. The initial cell voltage for continuous operation durability evaluation was 0.571 V, and the cell voltage holding ratio was 91.8%. On the other hand, the initial cell voltage in the start / stop durability evaluation was 0.571 V, and the cell voltage holding ratio was 89.7%. The configuration and results are summarized in Tables 1 and 2.

Example 9
1. Preparation of electrode catalyst layer (1) To a glass container in a water bath set to be kept at 20 ° C., ultrapure water, a solid polymer electrolyte solution (Nafion solution DE520 manufactured by DuPont, electrolyte content 5% by weight), Next, ethylene glycol (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent) was gradually added dropwise and mixed and stirred for 10 minutes using a homogenizer. Subsequently, an electrode catalyst (TEC10E50E manufactured by Tanaka Kikinzoku Kogyo Co., Ltd .: 50% by weight of platinum supported on Ketjen Black, average platinum particle size of 3 nm) was added to this solution, and the mixture was stirred and stirred for 1 hour to obtain an electrode catalyst ink 1. The electrode catalyst ink 1 was applied to both surfaces of a solid polymer electrolyte membrane (Nafion (registered trademark) NR-111, size 100 mm × 100 mm, thickness 25 μm) by a die coater method, and air-dried to form an electrode catalyst layer (1). Got. The obtained electrode catalyst layer (1) on the fuel electrode side and oxygen electrode side has an area of 50 mm × 50 mm, a Pt loading of 0.40 mg / cm ² , a thickness t ₁ = 36 μm, and an average pore diameter E ₁ = 0.14 μm. , Porosity V ₁ = 70%, average primary particle diameter D ₁ ′ = 20 nm of ketjen black, average secondary particle diameter D ₁ = 0.40 μm of ketjen black, weight of solid polymer electrolyte and ketjen black The ratio (solid polymer electrolyte / ketchen black) was 0.85.

2. Preparation of Gas Diffusion Layer Same as Example 1.

3. Preparation of electrode catalyst layer (2) To a glass container in a water bath set to be kept at 20 ° C., ultrapure water, a solid polymer electrolyte solution (DuPont Nafion solution DE520, electrolyte content 5 wt%), Next, ethylene glycol (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent) was gradually added dropwise and mixed and stirred for 10 minutes using a homogenizer. Next, an electrode catalyst (TEC 10E50E manufactured by Tanaka Kikinzoku Kogyo Co., Ltd .: 50% by weight of platinum supported on Ketjen Black, average platinum particle size of 3 nm) was added to this solution, and mixed and stirred for 40 minutes to obtain an electrode catalyst ink 2. . This electrode catalyst ink 2 was applied onto the gas diffusion layer produced above by a die coater method and air-dried to prepare two electrode catalyst layers (2) for the fuel electrode side and the oxygen electrode side. The obtained electrode catalyst layer (2) on the fuel electrode side and oxygen electrode side has an area of 50 mm × 50 mm, a Pt loading amount of 0.10 mg / cm ² , a thickness t ₂ = 18 μm, and an average pore diameter E ₂ = 0. .25 μm, porosity V ₂ = 73%, ketjen black average primary particle size D ₂ ′ = 20 nm, ketjen black average secondary particle size D ₂ = 0.52 μm, solid polymer electrolyte and ketjen black The weight ratio (solid polymer electrolyte / Ketjen black) was 0.85.

4). Assembly of MEA and Single Cell A membrane-electrode assembly was produced in the same manner as in Example 1, and a single cell for evaluation was prepared in the same manner as in Example 1.

  The durability of the evaluation single cell was evaluated in the same manner as in Example 1. The initial cell voltage for continuous operation durability evaluation was 0.536 V, and the cell voltage holding ratio was 95.1%. On the other hand, the initial cell voltage in the start / stop durability evaluation was 0.536 V, and the cell voltage holding ratio was 93.7%. The configuration and results are summarized in Tables 1 and 2.

(Comparative Example 1)
1. Preparation of Electrocatalyst Layer To a glass container in a water bath set to be kept at 20 ° C., ultrapure water and a solid polymer electrolyte solution (Nafion solution DE520 manufactured by DuPont, electrolyte content 5% by weight) are added, and then ethylene glycol (Wako Pure Chemical Industries, Ltd., special grade reagent) was gradually added dropwise and mixed and stirred for 10 minutes using a homogenizer. Next, an electrode catalyst (TEC10E50E manufactured by Tanaka Kikinzoku Kogyo Co., Ltd .: 50% by weight of platinum on Ketjen Black, average platinum particle size of 3 nm) was added to this solution, and the mixture was stirred for 3 hours to obtain an electrode catalyst ink. This electrode catalyst ink was applied to both surfaces of a solid polymer electrolyte membrane (Nafion (registered trademark) NR-111, size 100 mm × 100 mm, thickness 25 μm) by a die coater method and air-dried to obtain an electrode catalyst layer. The resulting electrode catalyst layer on the fuel electrode side and oxygen electrode side has an application area of 50 mm × 50 mm, a Pt loading of 0.50 mg / cm ² , a thickness of 12 μm, and an average primary particle diameter D ₁ ′ = 20 nm of Ketjen Black, Average pore diameter E ₁ = 0.045 μm, porosity V ₁ = 45%, average secondary particle diameter D ₁ = 0.10 μm of ketjen black, weight ratio of solid polymer electrolyte to ketjen black (solid polymer Electrolyte / Ketjen Black) was 0.85.

2. Preparation of Gas Diffusion Layer Same as Example 1.

3. Assembly of MEA and Single Cell A solid polymer electrolyte membrane having a fuel electrode side electrode catalyst layer and an oxygen electrode side electrode catalyst layer formed on both sides was sandwiched between two gas diffusion layers. Thereafter, a membrane-electrode assembly was produced by hot pressing for 3 minutes under the conditions of 120 ° C. and 20 kgf / cm ² ( ² Nm), and this was sandwiched between graphite separators, and further with a gold-plated stainless steel current collector plate. A single cell for evaluation was sandwiched.

  The durability of the evaluation single cell was evaluated in the same manner as in Example 1. The initial cell voltage for continuous operation durability evaluation was 0.620 V, and the cell voltage holding ratio was 91.1%. On the other hand, the initial cell voltage in the start / stop durability evaluation was 0.620 V, and the cell voltage holding ratio was 87.9%. The configuration and results are summarized in Tables 1 and 2.

(Example 10)
The membrane-electrode assembly produced in the same manner as in Example 1 is sandwiched between two graphite separators to form a single cell, and further, two stainless steel end plates are interposed via a current collector plate and an insulating plate. A fuel cell is manufactured by sandwiching and fastening the end plates with a fastening rod at a pressure of 4.5 kgf / cm ² (0.45 Nm) per unit area of each electrode on the fuel electrode side and oxygen electrode side. Evaluation was performed. The results are shown in Table 3.

  Here, an oxidant gas channel and a fuel gas channel having a groove width (W) of 1.0 mm and a groove depth (H) of 1.0 mm were formed in the graphite separator. The separator was provided with manifold holes for oxidant gas and fuel gas.

  Furthermore, as shown in Table 3, the groove width and the groove depth (represented by the groove width / groove depth) of each gas flow path of the two graphite separators are 0.6 mm / 1.0 mm in order, Except for changing to 0.8mm / 0.8mm, 1.2mm / 0.6mm, 0.8mm / 0.05mm, 0.4mm / 0.8mm, 1.6mm / 0.8mm, the same as above A fuel cell was fabricated and evaluated for initial performance. The results are shown in Table 3.

  As in Example 1, the initial performance evaluation of the fuel cell was performed according to the following procedure.

Atmospheric pressure, cell temperature of 70 ° C., hydrogen gas as fuel gas, and air as oxidant gas were supplied to a single cell of the fuel cell. For both gases, the cell outlet pressure is atmospheric pressure, hydrogen gas has a dew point of 60 ° C. and a relative humidity of 64% and a supply gas flow rate of 0.261 L / min, and air gas has a dew point of 60 ° C. and a relative humidity of 64% and a supply gas flow rate of 0. .625 L / min. Under this condition, the cell voltage (initial cell voltage) at a current density of 1.0 A / cm ² was measured.

V @ 1 A / cm ^{2 in} Table 3 refers to the cell voltage (V) at a current density of 1.0 A / cm ² (the same applies to Table 4).

  From the results of Table 3 above, the fuel gas flow path and the oxidant gas flow path should have a groove width exceeding 0.4 mm and less than 1.6 mm and groove depth exceeding 0.05 mm. It was confirmed that excellent initial performance could be expressed. From these experimental results, in any of the evaluation single cells of Example 11 below, the fuel gas flow path and the oxidant gas flow path were set to have a groove width of 1.0 mm and a groove depth of 1.0 mm. The durability was evaluated by evaluation and start / stop.

(Example 11)
The membrane-electrode assembly produced in the same manner as in Example 1 is sandwiched between two graphite separators to form a single cell, and further, two stainless steel end plates are interposed via a current collector plate and an insulating plate. The fuel cell was obtained by sandwiching and fastening the end plates with a fastening rod at a pressure of 4.5 kgf / cm ² (0.45 Nm) per unit area of each electrode on the fuel electrode side and oxygen electrode side.

  The graphite separator was formed with an oxidant gas passage and a fuel gas passage each having a groove width of 1.0 mm and a groove depth of 1.0 mm. The separator was provided with manifold holes for oxidant gas and fuel gas.

  The durability evaluation of the fuel cell was performed according to the following procedure, with the durability evaluation by continuous operation and the durability evaluation by start / stop being divided.

(1) Durability evaluation test by continuous operation Atmospheric pressure, cell temperature 70 ° C, hydrogen gas as fuel gas, air as oxidant gas, both gases are humidified at 60 ° C and supplied to single cell of fuel cell did. For both gases, the cell outlet pressure is atmospheric pressure, and after humidification, the hydrogen gas supplied to the single cell of the fuel cell has a dew point of 60 ° C., a relative humidity of 64% and a gas flow rate of 0.261 L / min, and the air gas has a dew point of 60 ° C. The relative humidity was 64% and the gas flow rate was 0.625 L / min. Under this condition, the cell voltage (initial cell voltage) at a current density of 1.0 A / cm ² was measured. Next, continuous operation is performed for 100 hours under these conditions, and the cell voltage holding ratio after continuous operation with respect to the initial cell voltage before continuous operation {(cell voltage after continuous operation for 100 hours / initial cell voltage) × 100 (%)} The durability was evaluated. The initial cell voltage was 0.620 V, and the cell voltage holding ratio with respect to the initial cell voltage before continuous operation was 98.1%. The results are shown in Table 4 and FIGS.

(2) Durability evaluation test by starting and stopping The initial cell voltage was measured under the same test conditions as in (1) above, and after one hour of continuous power generation, power generation was terminated, and at the end both the fuel electrode and oxygen electrode were single. The gas supply to the cell was stopped, the single cell was left for 10 minutes, and the continuous operation was performed again for 1 hour under the same conditions. This operation is performed as a start / stop condition, and is performed 3000 times. The cell voltage holding ratio after start / stop with respect to the initial cell voltage {(cell voltage after start / stop 3000 times / initial cell voltage) × 100 (% )} Was defined as durability evaluation. The initial cell voltage was 0.620 V, and the cell voltage holding ratio after starting and stopping with respect to the initial cell voltage was 96.9%. The results are shown in Table 4 and FIGS.

  Furthermore, as shown in Table 4, durability evaluation by continuous operation in the same manner as above except that the fastening pressure of the end plate, and the relative humidity of the hydrogen gas and air gas supplied to the fuel cell were changed, and Durability was evaluated by starting and stopping. These results are also shown in Table 4 and FIGS.

  From the results of Table 4 and FIGS. 4 to 5, the optimum behavior of the cell voltage differs depending on the fastening pressure (cell fastening force) of the fuel cell, and depends on the relative humidity (especially oxidant gas = air) of the supply gas during operation. Thus, it was confirmed that the desired power generation performance (cell performance) can be maintained over a long period of time by optimizing the fastening pressure (cell fastening force) of the fuel cell. Specifically, it shows that a high cell voltage (initial cell voltage) is expressed (see Table 4 and FIG. 4), and this high voltage can be maintained for a long period of time for subsequent continuous operation and start / stop operation ( It was confirmed that the durability performance by continuous operation and the durability performance by starting and stopping can be improved.

  In addition, each graph of RH (= relative humidity) 25%, RH40%, RH64%, and RH80% in FIG. 4 is for each relative humidity (%) of the air gas supplied to the single cell for evaluation of the fuel cell. It is a graph showing the relationship between a fastening pressure and a cell voltage (initial cell voltage).

  Further, the graphs of RH (relative humidity) 25% (1), RH 40% (1), RH 64% (1), and RH 80% (1) in FIG. 5 are respectively supplied to single cells for evaluation of the fuel cell. It is a graph showing the relationship between the fastening pressure for every relative humidity (%) of the air gas and the retention rate of the cell voltage after continuous operation with respect to the initial cell voltage before continuous operation.

  Further, the graphs of RH (relative humidity) 25% (2), RH 40% (2), RH 64% (2), and RH 80% (2) in FIG. 5 are respectively supplied to the single cells for evaluation of the fuel cell. It is a graph showing the relationship between the fastening pressure for every relative humidity (%) of the air gas and the retention rate of the cell voltage after starting and stopping with respect to the initial cell voltage before starting and stopping.

  According to the electrode catalyst layer for a fuel cell of the present invention, it is possible to provide a fuel cell excellent in durability.

The schematic cross section of the electrode catalyst layer which is preferable one Embodiment of this invention is shown. The schematic cross section showing the fundamental composition of the single cell of the fuel cell which is one preferred embodiment of the present invention is shown. FIG. 3 is a perspective view for explaining a preferable example of a basic configuration of a fuel cell stack formed by stacking a plurality of single cells of FIG. 2. It is the graph which represented the relationship between the fastening pressure of the single cell for evaluation of the fuel cell produced in Example 11, and the initial cell voltage for every relative humidity of the air supplied to the single cell of a fuel cell. The relationship between the fastening pressure of the single cell for evaluation of the fuel cell produced in Example 11 and the retention rate of the cell voltage after the continuous operation with respect to the initial cell voltage before the continuous operation of the air supplied to the single cell of the fuel cell The relationship between the graph expressed for each relative humidity and the fastening pressure of the single cell for evaluation of the fuel cell produced in Example 11 and the retention rate of the cell voltage after start-up and stop with respect to the initial cell voltage before start-stop It is the graph represented for every relative humidity of the air supplied to a single cell.

Explanation of symbols

10 Fuel cell stack,
20 stack part (stacked stack),
30, 40 current collector plate,
35, 45 Output terminal 50, 60 Insulating plate,
70 fuel electrode side end plate,
80 oxygen electrode side end plate,
71 Fuel gas inlet,
72 Fuel gas outlet,
74 Oxidant gas inlet,
75 Oxidant gas outlet,
77 Cooling water inlet,
78 Cooling water outlet,
90 tie rods,
101 conductive carrier (secondary particles),
102 conductive carrier (secondary particles),
120 electrode catalyst layer,
121 electrode catalyst layer (1),
122 electrode catalyst layer (2),
200 Fuel cell (stack),
201 single cell of fuel cell,
210 solid polymer electrolyte membrane,
220a Fuel electrode side electrode catalyst layer,
220b oxygen electrode side electrode catalyst layer,
230a Fuel electrode side gas diffusion layer,
230b oxygen electrode side gas diffusion layer,
240 MEA,
250a Fuel electrode side separator,
250b oxygen electrode side separator,
251a Fuel gas flow path (supply groove),
251b Oxidant gas flow path (supply groove),
W Gas channel groove width,
H Gas channel groove depth.

Claims (18)

An electrode catalyst layer for a fuel cell comprising at least an electrode catalyst in which catalyst particles are supported on a conductive support and a solid polymer electrolyte,
The electrode catalyst layer for a fuel cell is an electrode catalyst layer for a fuel cell in which the average secondary particle diameter of the conductive support increases in the thickness direction. The electrode catalyst layer for a fuel cell is formed by laminating at least two layers of an electrode catalyst layer (1) and an electrode catalyst layer (2), and the conductive carrier contained in the electrode catalyst layer (1). _2. The fuel cell electrode catalyst layer according to claim 1, wherein an average secondary particle diameter (D ₁ ) is smaller than an average secondary particle diameter (D ₂ ) of the conductive support contained in the electrode catalyst layer (2).   The electrode catalyst layer for a fuel cell according to claim 1 or 2, wherein an average secondary particle diameter of the conductive support is less than 1 µm. The average secondary particle diameter (D ₁ ) of the conductive carrier contained in the electrode catalyst layer (1) and the average secondary particle diameter (D 2) of the conductive carrier contained in the electrode catalyst layer ( ₂ ). DOO _{is, 0.05 <D 1 / D 2} <1 a fuel cell electrode catalyst layer according to any of claims 1 to 3. The electrode catalyst for fuel cells according to any one of claims 1 to 4, wherein an average pore diameter (E ₁ ) of the electrode catalyst layer ( ₁ ) is smaller than an average pore diameter (E ₂ ) of the electrode catalyst layer (2). layer. Wherein the average pore diameter of the electrode catalyst layer (1) _{(E 1),} the electrode catalyst layer (2) Average pore diameter _{(E 2),} but claims a _{0.1 <E 1 / E 2 <} 1 The electrode catalyst layer for fuel cells in any one of 1-5. The porosity of the electrode catalyst layer (1) and _{(V 1),} the porosity of the electrode catalyst layer (2) and _{(V 2)} but, according to claim 1 which is _{0.15 <V 1 / V 2 <} 1 The electrode catalyst layer for fuel cells according to any one of 6.   The electrode catalyst layer for a fuel cell according to any one of claims 1 to 7, wherein the porosity of the electrode catalyst layer for a fuel cell is 10 to 90% by volume. The thickness (t ₁ ) of the electrode catalyst layer ( ₁ ) and the thickness (t ₂ ) of the electrode catalyst layer (2) satisfy 0.1 <t ₁ / t ₂ <5. The electrode catalyst layer for fuel cells according to any one of the above.   The electrode catalyst layer for fuel cells according to any one of claims 1 to 9, wherein the electrode catalyst layer for fuel cells has a thickness of 1 to 50 µm. In the fuel cell membrane-electrode assembly in which the oxygen electrode side electrode catalyst layer and the fuel electrode side electrode catalyst layer are arranged to face both surfaces of the solid polymer electrolyte membrane, and the gas diffusion layer is sandwiched between them.
At least one of the oxygen electrode side electrode catalyst layer and the fuel electrode side electrode catalyst layer is the electrode catalyst layer for a fuel cell according to any one of claims 1 to 10, and the solid polymer electrolyte membrane A membrane-electrode assembly for a fuel cell, which is disposed in contact with the electrode catalyst layer (1).   A fuel cell using the fuel cell membrane-electrode assembly according to claim 11. A fuel electrode side separator having a fuel gas passage for supplying and discharging fuel gas from both sides of the fuel cell membrane-electrode assembly in the thickness direction; and an oxidant gas. And at least one single cell sandwiched by an oxygen electrode side separator having an oxidant gas flow path for supplying and discharging gas, and further fastened by a pair of end plates from both sides in the thickness direction of the single cell. A fuel cell comprising
The fuel cell, wherein a fastening pressure applied to the electrode in the fuel cell membrane-electrode assembly by the fastening is 3 to 9 kgf / cm ² per unit area of the electrode.   The fuel cell according to claim 13, wherein the fuel cell membrane-electrode assembly is the fuel cell membrane-electrode assembly according to claim 11. The said fastening pressure is 7 kgf / cm ² or more and 9 kgf / cm ² or less per unit area of the electrode when the relative humidity of the fuel gas and / or the oxidant gas is less than 30%. The fuel cell as described. The fuel gas and / or the time the relative humidity of the oxidant gas is less than 30% to 50% the fastening pressure, claim 13 wherein a unit 5 kgf / cm ² or more 7 kgf / cm less than ² per area of electrode The fuel cell according to any one of -15. Wherein when the relative humidity of the fuel gas and / or the oxidant gas is 50% or more, the fastening pressure, according to claim 13 to 16 wherein the electrode is less than 3 kgf / cm ² or more 5 kgf / cm ² per unit area of the The fuel cell according to any one of the above.   The fuel gas channel and the oxidant gas channel have a groove width of 0.5 to 1.5 mm and a groove depth of 0.1 to 1.2 mm, respectively. A fuel cell according to claim 1.

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