JP2006004916A - Mea for fuel cell and fuel cell using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the amount of use of an expensive precious metal catalyst such as platinum without causing degradation in performance. <P>SOLUTION: The aforementioned problem is solved by providing an MEA for a fuel cell comprising a cathode catalyst layer and an anode catalyst layer formed to be opposed to each other on both surfaces of a solid polymer electrolyte membrane, the cathode and anode catalyst layers each including a solid polymer electrolyte and a catalyst-carrying carbon made of a conductive carbon carrying the catalyst. The ratio of the thickness of the anode catalyst layer to that of the cathode catalyst layer is 0.7 to 1.3. The mass of the catalyst per unit area of the anode catalyst layer is 1/2 or less of that of the cathode catalyst layer in mass ratio. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a solid polymer electrolyte fuel cell, and more particularly to an electrode catalyst layer of a solid polymer electrolyte fuel cell.

  A fuel cell is a system that generates electricity by electrochemically reacting hydrogen (fuel) with oxygen. Since the product of this reaction is water in principle, there is little impact on the environment. Among them, solid polymer electrolyte fuel cells are different from other fuel cells such as solid oxide type, molten carbonate type, and phosphoric acid type. Since it can operate at a low temperature, it is expected to be used as a power source for moving vehicles such as automobiles, and is being developed.

  A solid polymer electrolyte fuel cell includes a solid polymer electrolyte membrane having hydrogen ion conductivity, and two electrodes sandwiching the membrane, that is, an anode to which hydrogen is supplied and a cathode to which oxygen is supplied. This is a basic configuration that is called a membrane-electrode assembly (MEA). The electrode is a porous electrode formed of a mixture of a catalyst-supporting carbon in which a catalyst is supported on conductive carbon and a solid polymer electrolyte having hydrogen ion conductivity, and is also referred to as a catalyst layer.

  In such an MEA, as shown in the following chemical formula, an oxidation reaction of hydrogen that converts a hydrogen-containing gas of a fuel into hydrogen ions at an anode and an oxygen contained in an oxidant gas are reduced at a cathode to reduce a solid polymer electrolyte. A reduction reaction of oxygen, which is combined with hydrogen ions that have passed through the membrane, becomes water. A solid polymer electrolyte fuel cell directly obtains electric energy from reaction energy obtained by such a chemical reaction.

The chemical reaction occurs on the three-phase interface in the catalyst layer where the catalyst, the solid polymer electrolyte, and the reaction gas exist. Therefore, at the three-phase interface, it is extremely important how the catalyst and the solid polymer electrolyte are in an appropriate state to increase the reaction site. As a technique for realizing this, for example, as described in Patent Document 1 or Patent Document 2, the catalyst-supporting carbon and the solid polymer electrolyte solution are mixed to form an ink, and this is applied and dried. The technique of forming a catalyst layer is taken. According to this method, the catalyst and the solid polymer electrolyte are brought into a desired dispersion state, and the electrode structure is optimized, so that the amount of catalyst is as small as possible.
JP 05-36418 A International Publication No. 02/015303 Pamphlet

  In a solid polymer electrolyte fuel cell, a catalyst that is an important material along with the solid polymer electrolyte membrane uses an expensive noble metal such as platinum for both the cathode and the anode. Therefore, reduction of the catalyst amount leads to reduction of manufacturing costs and the like, and is indispensable for spreading the solid polymer electrolyte fuel cells.

  Accordingly, an object of the present invention is to further reduce the amount of a catalyst containing an expensive noble metal such as platinum without causing a decrease in the performance of the MEA for fuel cells.

  As a result of intensive studies in view of the above problems, the present inventor has found that the above problems can be solved by appropriately setting the amount of catalyst contained in each of the anode catalyst layer and the cathode catalyst layer.

That is, in the present invention, a cathode catalyst layer and an anode catalyst layer containing a catalyst-supported carbon in which a catalyst is supported on conductive carbon and a solid polymer electrolyte are disposed opposite to both surfaces of the solid polymer electrolyte membrane. In the fuel cell MEA,
A ratio of the thickness of the anode catalyst layer to the cathode catalyst layer is 0.7 to 1.3;
The mass of the catalyst per unit area of the anode catalyst layer with respect to the mass of the catalyst per unit area of the cathode catalyst layer is 1/2 or less by mass ratio.
This problem is solved by the MEA for fuel cells.

  ADVANTAGE OF THE INVENTION According to this invention, even if it reduces the usage-amount of expensive catalysts, such as platinum, MEA for fuel cells which does not fall in performance can be provided.

In the first aspect of the present invention, a cathode catalyst layer and an anode catalyst layer including at least a catalyst-supported carbon in which a catalyst is supported on conductive carbon and a solid polymer electrolyte are disposed opposite to both surfaces of the solid polymer electrolyte membrane. In the fuel cell MEA,
A ratio of the thickness of the anode catalyst layer to the cathode catalyst layer is 0.7 to 1.3;
The mass of the catalyst per unit area of the anode catalyst layer with respect to the mass of the catalyst per unit area of the cathode catalyst layer is 1/2 or less by mass ratio.
A fuel cell MEA (hereinafter also simply referred to as “MEA”).

  As a chemical reaction for power generation in the MEA, the hydrogen oxidation reaction in the anode catalyst layer has a smaller activation overvoltage than the oxygen reduction reaction in the cathode catalyst layer. The research was conducted with a focus on reducing the amount of catalyst in the anode catalyst layer.

  Here, if it is attempted to reduce the amount of catalyst used in the entire MEA by simply reducing the mass of the catalyst layer on the anode side without reducing the catalyst content, the thickness of the catalyst layer changes between the anode and the cathode and there is a balance. The collapsed catalyst layer part may be bent. This is not only inconvenient when the MEA is incorporated into the cell, but also has a risk of degrading the performance of the resulting MEA due to a decrease in the degree of contact between the catalyst layer and the separator. In addition, when the thickness of the anode catalyst layer is reduced, there is a concern about performance deterioration due to lack of water. Therefore, it is difficult to sufficiently reduce the amount of catalyst in MEA.

  However, in the present invention, by reducing the amount of catalyst used in the anode catalyst layer while keeping the balance of the thickness of the anode catalyst layer and the cathode catalyst layer within the specified range, the catalyst performance can be reduced without degrading the MEA performance. It has been found that the amount used can be reduced. As a result, the manufacturing cost of MEA can be reduced.

  Hereinafter, the MEA of the present invention will be described in more detail.

  As described above, the basic configuration of the MEA of the present invention has a configuration in which the cathode catalyst layer and the anode catalyst layer are disposed to face both surfaces of the solid polymer electrolyte membrane. The catalyst layer used on each of the cathode side and the anode side includes a catalyst-supporting carbon in which a catalyst is supported on conductive carbon, and a solid polymer electrolyte.

  In the MEA of the present invention, the ratio of the thickness of the anode catalyst layer to the cathode catalyst layer is 0.7 to 1.3, preferably 0.75 to 1.25, more preferably 0.8 to 1.2. And If the thickness ratio is less than 0.7, the MEA may bend in the catalyst layer, and if it exceeds 1.3, the amount of catalyst used in the anode catalyst layer may not be sufficiently reduced.

  In addition, in the MEA, the mass of the catalyst per unit area of the anode catalyst layer is ½ or less with respect to the mass of the catalyst per unit area of the cathode catalyst layer. Thereby, the amount of catalyst used can be reduced without reducing the power generation performance of the MEA.

Here, the area in “per unit area” means the area of the surface of the catalyst layer in contact with the solid polymer electrolyte membrane. Therefore, in the present invention, the “mass of catalyst per unit area” is a value obtained by dividing the catalyst amount (g) contained in the catalyst layer by the area (cm ² ) of the catalyst layer on the solid polymer electrolyte membrane. .

  In the MEA of the present invention, in order to adjust the mass of the catalyst per unit area in each catalyst layer as described above, preferably, the content of the catalyst in the catalyst-supported carbon in the anode catalyst layer is set to the cathode. The content of the catalyst in the catalyst-supporting carbon in the catalyst layer is set to be smaller. Thereby, the thickness of the anode catalyst layer can be adjusted within a predetermined range while reducing the catalyst content contained in the anode catalyst layer.

  Specifically, the catalyst content in the catalyst-supported carbon in the anode catalyst layer is preferably 8% by weight to 35% by weight, more preferably 25% by weight to 35% by weight. The content is preferably 8% by weight or more from the viewpoint of electrode reaction activity, and preferably 35% by weight or less from the viewpoint of reducing the amount of catalyst.

  The catalyst content in the catalyst-supported carbon in the cathode catalyst layer is preferably more than 35% by weight and 70% by weight or less, more preferably 40% by weight or more and 60% by weight or less. The content is preferably more than 35% by weight from the viewpoint of electrode reaction activity, and preferably 70% by weight or less from the viewpoint of catalyst dispersibility.

  The catalyst content in the catalyst-supported carbon can be measured by inductively coupled plasma emission spectroscopy (ICP).

  In the MEA of the present invention, the mass of the catalyst per unit area in each catalyst layer can be adjusted as described above by adding conductive carbon on which no catalyst is supported on the anode catalyst layer. This also makes it possible to adjust the thickness of the anode catalyst layer within a predetermined range while reducing the catalyst content contained in the anode catalyst layer.

  The conductive carbon on which the catalyst is not supported may be any carbon having sufficient electronic conductivity as a current collector, and the main component is preferably carbon.

  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 weight or less is allowed.

  Specific examples of the conductive carbon include carbon particles such as carbon black, activated carbon, coke, natural graphite, and artificial graphite. The size of the carbon particles is not particularly limited, but from the viewpoint of controlling the thickness of the catalyst layer within an appropriate range, the average primary particle diameter is 5 to 200 nm, preferably about 10 to 100 nm. Good.

  Especially, since the said conductive carbon is excellent in electronic conductivity, it is preferable to use carbon black. The carbon black is preferably at least one selected from the group consisting of ketjen black EC, ketjen black EC600JD, Vulcan XC72R, and black pearl 2000.

More preferably, the carbon black heat-treated is used as the conductive carbon on which the catalyst is not supported. Thereby, the conductive carbon which is excellent in not only electronic conductivity but corrosion resistance is obtained. The heat-treated carbon black has a G band obtained from Raman spectrum of preferably 55 cm ⁻¹ or less, more preferably 52 cm ⁻¹ or less, particularly preferably 49 cm ⁻¹ or less. As the crystallinity of the conductive carbon increases, a three-dimensional crystal lattice resembling a graphite structure is formed. The smaller the full width at half maximum of the G band, the higher the crystallinity, the better the corrosion resistance, and the less impurity carbon.

Here, the Raman spectrum is a spectrum indicating which light of which wavelength is scattered with what intensity with respect to the light scattered by the Raman effect. In the present invention, the half-width of the G band can be calculated using a spectrum in which the wave number (cm ⁻¹ ) is represented as one axis and the intensity is represented as the other axis. The “G band” refers to a peak indicating the crystallinity of carbon that appears in the vicinity of 1580 cm ⁻¹ in a spectrum obtained by Raman measurement of carbon particles. Further, the “half-value width” is a value used for determining the distribution state of a predetermined absorption band, and refers to the spread width of the absorption band at a half height of the peak height of the absorption band.

  In the present invention, the Raman measurement of conductive carbon can be performed using a known Raman spectrometer. The Raman spectrometer is not particularly limited as long as the G band can be measured with a certain reproducibility. However, when the shape and position of the G band differ depending on the Raman spectroscopic measurement device, the Raman spectrum measured by the method described in the examples described later is used as the reference spectrum.

  If there is another absorption band in the vicinity of the G band and the half-value width cannot be determined from the spectrum at first glance because it is bonded to the G band, the half-width is usually reduced by an analysis program attached to the Raman spectrometer. The price range can be determined. For example, a half-width is determined by a process of drawing a straight base line in an area including a G-band peak, performing a Lorentz waveform curve fit, and performing G-band peak separation.

Carbon black formed by heat treatment with a G band half width of 55 cm ⁻¹ or less is obtained by heat-treating the above-described carbon black at a high temperature of about 1500 to 3000 ° C. The heat treatment time is not particularly limited, but about 1 to 10 hours is sufficient.

As the conductive carbon on which the catalyst is not supported, carbon black produced using acetylene as a raw material, such as acetylene black, can also be used. Acetylene black and the like are produced by thermal decomposition of acetylene, but because the purity of acetylene, which is a raw material, is high (99% or more) and because of high temperature during decomposition, the microcrystalline structure of the particles develops into a graphite shape. It is said that the carbon content is high (99.5% or more) compared to other carbon blacks. Therefore, it has excellent corrosion resistance and is suitable as conductive carbon. From the viewpoint of corrosion resistance, the carbon black produced using acetylene as a raw material has a half-width of the G band obtained from Raman spectrum of preferably 55 cm ⁻¹ or less, more preferably 52 cm ⁻¹ or less, particularly preferably 49 cm ^{−. 1} or less is used.

  In addition to the above-described conductive carbon on which no catalyst is supported, at least one selected from the group consisting of carbon nanotubes, carbon nanohorns, and carbon nanofibers is preferably used. Since these have a higher degree of graphitization than carbon black, they are excellent in corrosion resistance and can improve the durability of MEA.

  In addition, as for the conductive carbon on which the catalyst used for the anode catalyst layer is not supported, only one kind of those described above may be used alone, or two or more kinds may be mixed and used as desired. What is necessary is just to determine suitably and use so that MEA which has a characteristic may be obtained.

  In the anode catalyst layer, the content of the conductive carbon on which the catalyst is not supported is the total mass of the conductive carbon contained in the anode catalyst layer (the conductive carbon in the catalyst-supported carbon contained in the anode catalyst layer). And the total mass of conductive carbon on which no catalyst is supported) is preferably 5 to 80% by weight, more preferably 10 to 75% by weight. Thereby, it becomes easy to adjust the balance of the thickness of the anode catalyst layer and the cathode catalyst layer to a desired value.

  In the MEA of the present invention, the catalyst content is different in each catalyst layer in the anode and the cathode, so the solid polymer electrolysis mass contained in each catalyst layer also needs to be appropriate. In the catalyst layer, if the solid polymer electrolysis mass is too small, there is a risk that the formation of a three-phase interface where the electrode reaction proceeds may be insufficient. There is a risk that water will easily accumulate, and this will adversely affect performance.

  Considering these, the mass of the solid polymer electrolyte in the anode catalyst layer is the total mass of the conductive carbon contained in the anode catalyst layer (the conductive carbon and the catalyst in the catalyst-carrying carbon contained in the anode catalyst layer are supported). 0.4 to 0.9, preferably 0.6 to 0.9 with respect to 1) (total mass of conductive carbon that is not). The mass of the solid polymer electrolyte in the cathode catalyst layer is 0.6 to 1.2, preferably 0.8 to 1.2, based on the total mass 1 of conductive carbon contained in the cathode catalyst layer.

  In the anode catalyst layer, the conductive carbon similar to the conductive carbon on which the catalyst is not supported is preferably 5% by weight or more, more preferably 10% in the conductive carbon in the catalyst-supported carbon in the anode catalyst layer. It is good to contain by weight% or more. As a result, the corrosion resistance of the conductive carbon in the anode catalyst layer and the electron conductivity of the anode catalyst layer can be improved.

  In the MEA of the present invention, the thickness of each catalyst layer in the anode and the cathode is not particularly limited, but is 0.1 to 100 μm, preferably 1 to 20 μm. If the thickness of the catalyst layer is less than 0.1 μm, the desired power generation amount may not be obtained, and if it exceeds 100 μm, it may not be possible to achieve high output.

  In the MEA of the present invention, the cathode catalyst layer may further contain carbon black that has been heat-treated as conductive carbon on which no catalyst is supported. The heat-treated carbon black is excellent in hydrophobicity due to a decrease in hydrophilic functional groups. Thereby, the drainage property of the cathode catalyst layer can be improved, and consequently the power generation performance of the MEA can be improved.

  Specifically, the carbon black used for the heat-treated carbon black is preferably at least one selected from the group consisting of ketjen black EC, ketjen black EC600JD, Vulcan XC72R, and black pearl 2000.

From the viewpoint that the heat-treated carbon black is excellent in hydrophobicity, the G band half width obtained from the Raman spectrum is preferably 55 cm ⁻¹ or less, more preferably 52 cm ⁻¹ or less, particularly preferably 49 cm ⁻¹ or less. It is better to use something. Since this is the same as that described above for the conductive carbon in which no catalyst is supported in the anode catalyst layer, detailed description thereof is omitted.

The cathode catalyst layer may further contain carbon black produced using acetylene such as acetylene black as a conductive carbon on which no catalyst is supported, from the viewpoint of excellent hydrophobicity. This also improves the drainage performance of the cathode catalyst layer, which in turn improves the power generation performance of the MEA. Carbon black produced using acetylene as a raw material has a half band width of G band obtained from Raman spectrum of preferably 55 cm ⁻¹ or less, more preferably 52 cm ⁻¹ or less, particularly preferably 49 cm ⁻¹ or less. . Since this is the same as that described above for the conductive carbon in which no catalyst is supported in the anode catalyst layer, detailed description thereof is omitted.

  From the viewpoint of excellent hydrophobicity, the cathode catalyst layer may further include at least one selected from the group consisting of carbon nanotubes, carbon nanohorns, and carbon nanofibers as conductive carbon on which no catalyst is supported. Good. This also improves the drainage performance of the cathode catalyst layer, which in turn improves the power generation performance of the MEA.

  In addition, as for the conductive carbon on which the catalyst used for the cathode catalyst layer is not supported, only one kind of the above-mentioned ones may be used alone, or two or more kinds may be mixed and used as desired. What is necessary is just to determine suitably and use so that MEA which has a characteristic may be obtained.

  In the cathode catalyst layer, the same conductive carbon as the above-described conductive carbon on which the catalyst is not supported is preferably 5% by weight or more, more preferably 10% in the conductive carbon in the catalyst-supported carbon in the cathode catalyst layer. It is good to contain by weight% or more. As a result, it is possible to improve the corrosion resistance of the conductive carbon in the cathode catalyst layer and the electron conductivity of the cathode catalyst layer.

  In the catalyst-supported carbon used in the present invention, the conductive carbon on which the catalyst is supported has a specific surface area for supporting the catalyst in a desired dispersed state, and has sufficient electronic conductivity as a current collector. The main component is preferably carbon. Specific examples include carbon particles made of carbon black, activated carbon, coke, natural graphite, artificial graphite and the like. In the present invention, “the main component is carbon” is as described above. The size of the carbon particles is not particularly limited, but from the viewpoint of controlling the thickness of the catalyst layer within an appropriate range, the average primary particle diameter is 5 to 200 nm, preferably about 10 to 100 nm. Good.

  Especially, since the said conductive carbon is excellent in electronic conductivity, it is preferable to use carbon black. Preferred examples of the carbon black include those listed above as conductive carbons on which no catalyst is supported. More preferably, the carbon black is heat-treated because of its excellent electron conductivity and corrosion resistance.

Specifically, as the heat-treated carbon black in the catalyst-supported carbon, the half band width of the G band obtained from Raman spectrum is preferably 55 cm ⁻¹ or less, more preferably 52 cm ⁻¹ or less, particularly preferably 49 cm ^{−. 1} or less is used. Since this is the same as that described above for the conductive carbon on which the catalyst used for the anode catalyst layer is not supported, detailed description thereof is omitted.

Carbon black produced using acetylene as a raw material, such as acetylene black, can also be used as the conductive carbon on which the catalyst is supported. The carbon black produced using acetylene as a raw material has a G band obtained from Raman spectrum of preferably at least 55 cm ⁻¹ , more preferably 52 cm ⁻¹ or less, particularly preferably 49 cm ⁻¹ or less. Use. Since this is the same as that described above for the conductive carbon in which no catalyst is supported in the anode catalyst layer, detailed description thereof is omitted.

  In addition to the above-mentioned conductive carbon in the catalyst-supporting carbon, at least one selected from the group consisting of carbon nanotubes, carbon nanohorns, and carbon nanofibers is also preferably used. Since these have a higher degree of graphitization than carbon black, they are excellent in corrosion resistance and can improve the durability of MEA.

  The conductive carbon used for the catalyst-supporting carbon may be used alone or in combination of two or more of those described above, and an MEA having desired characteristics can be obtained. Thus, it may be determined and used as appropriate.

  The catalyst in the catalyst-supported carbon used in the present invention is required to have a catalytic action in the oxidation reaction of hydrogen and the reduction reaction of oxygen, and preferably contains at least platinum.

  Further, in order to improve the poisoning resistance, heat resistance, etc. with respect to carbon monoxide or the like, an alloy of platinum and other metals may be used. 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.

  The average particle size of the catalyst supported on the conductive carbon is preferably 1 to 30 nm. It is estimated that the catalyst activity is improved because the specific surface area increases as the average particle size decreases. However, in practice, even if the particle size of the catalyst is extremely small, the catalyst activity corresponding to the increase in the specific surface area is obtained. Therefore, the above range is preferable.

  The “average particle diameter of the catalyst” in the present invention is measured by the crystallite diameter obtained from the half-value width of the diffraction peak of the catalyst in X-ray diffraction or the average value of the fine particle diameter of the catalyst determined from a transmission electron microscope image. be able to.

  Although it does not specifically limit as a solid polymer electrolyte used for the catalyst layer in MEA of this invention, The member which has at least high proton conductivity is mentioned, Preferably the perfluorocarbon polymer which has a sulfonic acid group is mentioned. Particularly preferred are copolymers comprising polymerized units based on the following formula.

(In the formula, l and m are integers, p is an integer of 0 to 3, q is 0 or 1, n is an integer of 1 to 12, and X is a fluorine atom or a trifluoromethyl group. is there.)
The solid polymer electrolyte used for the catalyst layer may be the same type as the solid polymer electrolyte membrane described later, or may be a different type.

  In the MEA of the present invention, it is preferable that at least one of the anode catalyst layer and the cathode catalyst layer further contains a polymer containing a fluorine atom. Thereby, the water repellency of the resulting catalyst layer can be increased, and water generated during power generation can be quickly discharged. The polymer containing a fluorine atom is more preferably used at least in a cathode catalyst layer that easily causes a flooding phenomenon.

  Examples of the polymer containing fluorine atoms include at least one polymer selected from the group consisting of polytetrafluoroethylene, polyhexafluoropropylene, and tetrafluoroethylene-hexafluoropropylene copolymers.

  The content of the polymer containing fluorine atoms is preferably 5 to 80% by weight, more preferably 10 to 70% by weight, based on the total mass of the conductive carbon contained in the anode catalyst layer or the cathode catalyst layer. It is good to do. By setting it as such a range, drainage can be improved, without reducing the power generation performance of MEA.

  In the present invention, the catalyst layer may be produced according to a conventionally known method. For example, a solid polymer electrolyte and catalyst-supported carbon are mixed with water or an alcohol solvent to form a catalyst layer ink, which is a base such as a gas diffusion layer, a solid polymer electrolyte membrane, or a polytetrafluoroethylene (PTFE) sheet. For example, a method of drying after coating on a material.

  The catalyst layer ink includes a polymer containing fluorine atoms such as polytetrafluoroethylene, polyhexafluoropropylene, and tetrafluoroethylene-hexafluoropropylene copolymer in addition to the solid polymer electrolyte and catalyst-supporting carbon. Various additives may be included.

  Next, the solid polymer electrolyte membrane used in the MEA of the present invention is not particularly limited, and examples thereof include those made of the same solid polymer electrolyte as listed in the description of the catalyst layer. Examples thereof include Nafion (registered trademark, manufactured by DuPont), Flemion (registered trademark, manufactured by Asahi Glass Co., Ltd.), Aciplex (registered trademark, manufactured by Asahi Kasei Co., Ltd.), and the like. In addition, fluoropolymer electrolytes such as ion exchange resins manufactured by Dow Chemical Co., ethylene-tetrafluoroethylene copolymer resin membranes, resin membranes based on trifluorostyrene, and hydrocarbons having sulfonic acid groups A resin film or the like may be used.

  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.

  What is necessary is just to perform according to a conventionally well-known method as a manufacturing method of MEA of this invention. For example, a method of forming a catalyst layer on a gas diffusion layer as described above, sandwiching a solid polymer electrolyte membrane using two of them, and then hot pressing may be used.

  Hot pressing is preferably performed at 110 to 170 ° C. and a pressing pressure of 0.1 to 10 MPa with respect to the electrode surface. Thereby, the bondability between the solid polymer electrolyte membrane and the catalyst layer can be enhanced.

  In addition, when a catalyst layer is formed on a PTFE sheet or the like, a solid polymer electrolyte membrane is sandwiched so that the catalyst layer is on the inside, and hot pressing is performed in the same manner as described above, and then only the PTFE sheet is formed. Remove it.

  In the MEA of the present invention, a gas diffusion layer may be disposed on the surface of the catalyst layer opposite to the surface in contact with the solid polymer electrolyte membrane. The gas diffusion layer is not particularly limited, and examples thereof include those based on 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. Further, in order to enhance water repellency and prevent flooding phenomenon, the gas diffusion layer is subjected to water repellency using known means, or a carbon particle layer composed of carbon particle aggregates is formed on the gas diffusion layer. Is preferred.

  Examples of the method for performing the water-repellent treatment include a method for performing the water-repellent treatment by immersing the gas diffusion layer in a dispersion of a polymer having a fluorine atom such as polytetrafluoroethylene and then drying by heating in an oven or the like. It is done.

As a method for forming a carbon particle layer on the gas diffusion layer, first, carbon atoms such as carbon black, fluorine atoms such as polytetrafluoroethylene, polyhexafluoropropylene, tetrafluoroethylene-hexafluoropropylene copolymer are used. A slurry is prepared by dispersing a polymer or the like contained in a solvent such as water, alcohol solvents such as perfluorobenzene, dichloropentafluoropropane, methanol, and ethanol. Next, the slurry is applied on the gas diffusion layer and dried, or the slurry is once dried and pulverized to form a powder, which is then applied onto the gas diffusion layer. In the method, the gas diffusion layer on which the carbon particle layer is formed is preferably heat-treated at about 300 to 400 ° C. using a muffle furnace or a firing furnace.

  The content of the polymer containing fluorine atoms in the carbon particle layer is preferably 0.1 to 2.0, more preferably 0.2 to 1.8, and still more preferably, with respect to the mass 1 of the carbon particles. 0.3 to 1.5. The carbon particle layer is preferably 0.1 or more from the viewpoint of water repellency, and preferably 2.0 or less from the viewpoint of conductivity.

  As described above, the MEA of the present invention can reduce the amount of expensive catalyst such as platinum used, and can reduce the manufacturing cost of the MEA. The type of fuel cell in which such MEA is used is not particularly limited, but is preferably used as a solid polymer electrolyte fuel cell (also simply referred to as “PEFC”) from the viewpoint of practicality and safety. . The configuration of PEFC is not particularly limited, but has a structure in which MEA is sandwiched between separators.

  As the separator, a known separator such as a carbon separator such as dense carbon graphite or a carbon plate or a metal separator such as stainless steel may be used. The separator has a function of separating air and fuel gas, and a gas flow groove may be formed in order to secure the flow path, and a conventionally known technique can be appropriately used. The shape of the separator or the like is not particularly limited, and may be appropriately determined in consideration of the output characteristics of the obtained fuel cell.

  Furthermore, a stack in which a plurality of MEAs are stacked via a separator and connected in series may be formed so that a desired voltage or the like can be obtained by the PEFC. The shape of the PEFC is not particularly limited, and may be determined as appropriate so that desired battery characteristics such as voltage can be obtained.

  The fuel cell of the present invention is preferably used in vehicles such as automobiles that require high performance and low cost. Since the manufacturing cost of the fuel cell of the present invention is reduced without degrading the power generation performance, the cost of the vehicle can be reduced by using it as a power source for driving the vehicle.

  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.

  The G band half-width of carbon used in each example was measured according to the following apparatus and conditions.

・ Measuring device Microscopic laser Raman spectroscopic analyzer Holo Lab 5000R
(Kaiser Optical System Inc.)
Measurement conditions Excitation wavelength: 532 nm
Output: 3mW
Measurement time: exposure 30 seconds × total 5 times [Example 1]
1. Preparation of MEA (1-1) Preparation of catalyst layer ink-Anode-side carbon Ketjen black EC (manufactured by Ketjen Black International Co., Ltd .; G band half-value width: 68 cm ^-1 ;) with catalyst supported on platinum 5 g of carbon (platinum content 29% by weight), solid polymer electrolyte dispersion (Nafion dispersion DE520 manufactured by DuPont, electrolyte content 5% by weight) 50.4 g (solid to mass 1 of all conductive carbon in the catalyst layer) Polymer electrolyte mass is 0.71), pure water 12.5 g, 2-propanol (special grade reagent manufactured by Wako Pure Chemical Industries, Ltd.) 5 g in a glass container in a water bath set to hold at 25 ° C., homogenizer Was mixed and dispersed for 3 hours to obtain an anode catalyst layer ink.

Cathode side 5 g of catalyst-supported carbon (platinum content 49% by weight) in which platinum is supported as a catalyst on the same carbon as the anode side, 43.9 g of the same solid polymer electrolyte dispersion as the anode side (total conductivity in the catalyst layer) The mass of the solid polymer electrolyte is 0.86) with respect to the mass of the conductive carbon, 12.5 g of pure water, and 5 g of 2-propanol in a glass container in a water bath set to hold at 25 ° C. The resulting mixture was dispersed for 3 hours to obtain a cathode-side catalyst layer ink.

(1-2) Catalyst Layer Formation Two types of catalyst layer inks previously prepared using a screen printer were applied on one side of a 200 μm-thick PTFE sheet (Nichias Naflon sheet) for 30 minutes at room temperature. After drying, it was cut into a square with a side of 5 cm and used as an anode and cathode catalyst layer.

(1-3) MEA conversion A PTFE sheet on which a previously prepared anode and cathode catalyst layer was formed by sandwiching a solid polymer electrolyte membrane (DuPont's Nafion NR-111) with a square of 8 cm on a side and a thickness of 25 μm. Solid polymer electrolyte membranes are stacked so that the catalyst layer forming sides face each other, hot pressed at 130 ° C. for 10 minutes at a pressure of 2.5 MPa per one-sided PTFE sheet area, and after cooling, only the PTFE sheet is peeled off. The catalyst layer was transferred to a MEA. The platinum mass per 1 cm ² of catalyst layer area on the electrolyte membrane after the transfer was 0.15 mg on the anode side and 0.40 mg on the cathode side. The thicknesses of the anode catalyst layer and the cathode catalyst layer were 10 μm and 12 μm, respectively.

2. Gas diffusion layer preparation (2-1) Carbon paper water repellent treatment Carbon paper (TGP-H-090, manufactured by Toray Industries, Inc.) having a thickness of 270 μm, and polytetrafluoroethylene (PTFE) dispersion (polyfluorone D-1E, manufactured by Daikin Industries, Ltd.) , 60% by weight), and then dried in an oven at 80 ° C. for 1 hour to disperse PTFE in the carbon paper. At this time, the PTFE content was 25 wt%.

(2-2) Formation of carbon particle layer 5.4 g of Vulcan XC72R (manufactured by CABOT) as carbon particles, 1.0 g of the same PTFE dispersion as (2-1), and 29.6 g of water were mixed for 3 hours using a homogenizer. Dispersed and slurried. The slurry was coated on one side of a carbon paper that had been subjected to water repellency treatment using a bar coater, then dried in an oven at 80 ° C. for 1 hour, and further heat treated in a muffle furnace at 350 ° C. for 1 hour. . As a result, the mass of the formed layer per 1 cm ^{2 of} carbon paper was 3.0 mg. Then, it cut out into a square of 6 cm on a side.

3. Single cell assembly for evaluation Two gas diffusion layers are stacked with the MEA sandwiched so that the carbon particle layers face each other, sandwiched by a graphite separator, and sandwiched by a gold-plated stainless steel current collector, A single cell for evaluation was used.

4). Single Cell Evaluation Power generation was performed by setting the single cell temperature to 70 ° C., the anode humidification temperature 59 ° C., and the cathode humidification temperature 59 ° C., and supplying hydrogen from the anode side and air from the cathode side at normal pressure. Under this condition, continuous power generation was performed at a current density of 1 A / cm ² to evaluate durability.

5). Evaluation results The power generation start voltage was 0.581 V, the voltage after continuous operation for 500 hours was 0.474 V, and the voltage maintenance ratio was 81.6%.

[Example 2]
In the preparation of the anode catalyst layer ink of (1-1) in Example 1, catalyst-supported carbon (platinum content 35% by weight) obtained by supporting platinum as a catalyst in Ketjen Black EC (G band half-value width: 68 cm ⁻¹ ). ), And 57.2 g of the solid polymer electrolyte dispersion (the mass of the solid polymer electrolyte is 0.88 with respect to 1 of the total conductive carbon in the catalyst layer), and the anode catalyst layer has a thickness of 9 μm. A single cell for evaluation was assembled and evaluated in the same manner as in Example 1 except that.

  As a result of the evaluation, the power generation start voltage was 0.589 V, the voltage after continuous operation for 500 hours was 0.484 V, and the voltage maintenance rate was 82.2%.

[Example 3]
In the preparation of the anode catalyst layer ink of (1-1) in Example 1, catalyst-supported carbon (platinum content 11% by weight) in which platinum was supported as a catalyst in Ketjen Black EC (G band half-value width: 68 cm ⁻¹ ). 37.4 g of the solid polymer electrolyte dispersion (the mass of the solid polymer electrolyte is 0.42 with respect to 1 of the total conductive carbon in the catalyst layer), and on the solid polymer electrolyte membrane after transfer A single cell for evaluation was assembled and evaluated in the same manner as in Example 1 except that the platinum mass per 1 cm ^{2 of the} catalyst layer area was 0.16 mg and the thickness of the anode catalyst layer was 15 μm.

  As a result of the evaluation, the power generation start voltage was 0.572 V, the voltage after continuous operation for 500 hours was 0.463 V, and the voltage maintenance rate was 80.9%.

[Example 4]
In the preparation of the cathode catalyst layer ink of (1-1) in Example 1, a catalyst-supported carbon (platinum content: 37% by weight) in which platinum was supported as a catalyst on Ketjen Black EC (G band half-value width: 68 cm ⁻¹ ). ), And the solid polymer electrolyte dispersion is 46.6 g (the mass of the solid polymer electrolyte is 0.74 with respect to the mass of all the conductive carbon in the catalyst layer is 0.74). A single cell for evaluation was assembled and evaluated in the same manner as in Example 1 except that the platinum mass per 1 cm ^{2 of the} catalyst layer area was 0.41 mg and the thickness of the cathode catalyst layer was 14 μm.

  The evaluation results were a power generation start voltage of 0.570 V, a voltage after continuous operation for 500 hours of 0.467 V, and a voltage maintenance ratio of 81.9%.

[Example 5]
In the preparation of the cathode catalyst layer ink of (1-1) in Example 1, a catalyst-supporting carbon (platinum content 62% by weight) in which platinum is supported as a catalyst on Ketjen Black EC (G band half-width: 68 cm ⁻¹ ). ) And 44.8 g of the solid polymer electrolyte dispersion (the mass of the solid polymer electrolyte is 1.18 with respect to the mass of all conductive carbon in the catalyst layer is 1.18), and on the solid polymer electrolyte membrane after transfer A single cell for evaluation was assembled and evaluated in the same manner as in Example 1 except that the platinum mass per cm ^{2 of the} anode catalyst layer was 0.42 mg and the thickness of the anode catalyst layer was 10 μm.

  As a result of the evaluation, the voltage at the start of power generation was 0.591 V, the voltage after continuous operation for 500 hours was 0.491 V, and the voltage maintenance rate was 83.1%.

[Example 6]
In the preparation of the cathode catalyst layer ink of (1-1) of Example 1, a catalyst-supporting carbon (platinum-containing carbon) in which an alloy of platinum and cobalt is supported as a catalyst on Ketjen Black EC (G band half-value width: 68 cm ⁻¹ ). The solid polymer electrolyte mass was 0.86 with respect to 13.0 mass of the total conductive carbon in the catalyst layer. In addition, except that the mass of platinum per cm ² of the catalyst layer area on the solid polymer electrolyte membrane after the transfer was 0.36 mg and the mass of cobalt was 0.04 mg, the evaluation unit A cell was assembled and evaluated.

  As a result of the evaluation, the voltage at the start of power generation was 0.599 V, the voltage after continuous operation for 500 hours was 0.497 V, and the voltage maintenance rate was 83.0%.

[Example 7]
In the preparation of the cathode catalyst layer ink of (1-1) of Example 1, Ketjen Black EC was subjected to a heat treatment at 2800 ° C. in a nitrogen atmosphere (G band half-width: 34 cm ^−1). The evaluation unit cell was assembled and evaluated in the same manner as in Example 4 except that catalyst-supporting carbon (platinum content: 37% by weight) supporting platinum as a catalyst was used.

  The evaluation results were a power generation start voltage of 0.577 V, a voltage after continuous operation for 500 hours of 0.480 V, and a voltage maintenance ratio of 83.2%.

[Example 8]
In the preparation of the cathode catalyst layer ink of (1-1) in Example 1, a catalyst was prepared by using highly crystalline acetylene black (G band half-value width: 45 cm ⁻¹ ; manufactured by Denki Kagaku Kogyo), which is carbon black produced using acetylene as a raw material. A single cell for evaluation was assembled and evaluated in the same manner as in Example 4 except that catalyst-supported carbon (platinum content: 37% by weight) supporting platinum was used.

  As a result of the evaluation, the voltage at the start of power generation was 0.580 V, the voltage after continuous operation for 500 hours was 0.489 V, and the voltage maintenance rate was 84.3%.

[Example 9]
In the preparation of the anode catalyst layer ink of (1-1) in Example 1, a catalyst-supported carbon (platinum-containing carbon) in which an alloy of platinum and ruthenium is supported as a catalyst on Ketjen Black EC (G band half-value width: 68 cm ⁻¹ ). In the preparation of the cathode catalyst layer ink of Example 1-1 (1-1) using a ratio of 25.5 wt% and a ruthenium content of 3.5 wt%, Ketjen Black EC (G band half width: 68 cm) ^-1 ) using catalyst-supported carbon (platinum content: 50% by weight) supporting platinum as a catalyst, 44.6 g of solid polymer electrolyte dispersion (solid to mass 1 of all conductive carbon in the catalyst layer) A single cell for evaluation was assembled and evaluated in the same manner as in Example 1 except that the mass of the polymer electrolyte was 0.86).

  As a result of the evaluation, the voltage at the start of power generation was 0.579 V, the voltage after continuous operation for 500 hours was 0.490 V, and the voltage maintenance rate was 84.6%.

[Example 10]
In the preparation of the anode catalyst layer ink of Example 1-1 (1-1), carbon whose crystallinity was increased by heat-treating Ketjen Black EC (manufactured by Ketjen Black International) at 2800 ° C. in a nitrogen atmosphere. In the preparation of the cathode catalyst layer ink of (1-1) in Example 1, using catalyst-supported carbon (platinum content 29% by weight) in which platinum was supported as a catalyst (G band half-width: 34 cm ⁻¹ ), Using ketjen black EC (G band half-width: 68 cm ⁻¹ ), a catalyst-supporting carbon (platinum content: 37% by weight) in which platinum is supported as a catalyst, 46.6 g of a solid polymer electrolyte dispersion (in the catalyst layer) The mass of the solid polymer electrolyte is 0.74) with respect to the mass of all conductive carbon 1, and the thickness of the cathode catalyst layer is 14 μm. In the same manner as in Example 1, assembled single cell for evaluation was evaluated it.

  The evaluation results were a power generation start voltage of 0.581 V, a 500 hour continuous operation voltage of 0.485 V, and a voltage maintenance rate of 83.5%.

[Example 11]
In the preparation of the anode catalyst layer ink of (1-1) in Example 1, a catalyst was prepared by using highly crystalline acetylene black (G band half-value width: 45 cm ⁻¹ ; manufactured by Denki Kagaku Kogyo), which is carbon black produced using acetylene as a raw material. In the preparation of the cathode catalyst layer ink of (1-1) of Example 1 using a catalyst-supported carbon (platinum content 29% by weight) supporting platinum as a ketchen black EC (G band half-value width: 68 cm ^{− 1} ) Using catalyst-supported carbon (platinum content: 37% by weight) supporting platinum as a catalyst in ¹ ), 46.6 g of solid polymer electrolyte dispersion (the amount of solids with respect to mass 1 of all conductive carbon in the catalyst layer) The evaluation unit cell was assembled in the same manner as in Example 1 except that the molecular electrolyte mass was 0.74) and the thickness of the cathode catalyst layer was 14 μm. It was evaluated.

  The evaluation results were a power generation start voltage of 0.591 V, a voltage after continuous operation for 500 hours of 0.502 V, and a voltage maintenance ratio of 84.9%.

[Example 12]
Ketjen Black EC (G band half-width: 68 cm ⁻¹ ) 5 g of catalyst-supporting carbon (platinum content 29% by weight) in which platinum is supported as a catalyst, Ketjen Black EC (G band half-width: 68 cm ⁻¹ ) 0 .39 g, solid polymer electrolyte dispersion (Nafion dispersion DE520, electrolyte content 5 wt%) 55.2 g (solid polymer electrolyte mass is 0.70 with respect to mass 1 of all conductive carbon in the catalyst layer), pure 12.5 g of water and 5 g of 2-propanol were mixed and dispersed for 3 hours using a homogenizer in a glass container in a water bath set to be kept at 25 ° C., thereby obtaining an anode catalyst layer ink.

  In the preparation of the cathode catalyst layer ink of (1-1) of Example 1 using the anode side catalyst layer ink, 43.4 g of solid polymer electrolyte dispersion (the mass of all conductive carbon in the catalyst layer was 1). On the other hand, a single cell for evaluation was assembled and evaluated in the same manner as in Example 1 except that the solid polymer electrolyte mass was 0.85) and the thickness of the anode catalyst layer was 11 μm.

  As a result of the evaluation, the voltage at the start of power generation was 0.569 V, the voltage after continuous operation for 500 hours was 0.470 V, and the voltage maintenance rate was 82.6%.

[Example 13]
Ketjen Black EC (G band half-width: 68 cm ⁻¹ ) 5 g of catalyst-supported carbon (platinum content 49% by weight) in which platinum is supported as a catalyst, Ketjen Black EC (G band half-width: 68 cm ⁻¹ ) 7 .65 g, solid polymer electrolyte dispersion (Nafion dispersion DE520, electrolyte content 5 wt%) 85.7 g (solid polymer electrolyte mass is 0.42 with respect to mass 1 of all conductive carbon in the catalyst layer), pure 12.5 g of water and 5 g of 2-propanol were mixed and dispersed for 3 hours using a homogenizer in a glass container in a water bath set to be kept at 25 ° C., thereby obtaining an anode catalyst layer ink.

In the preparation of the cathode catalyst layer ink of (1-1) of Example 1 using the anode side catalyst layer ink, 43.4 g of solid polymer electrolyte dispersion (the mass of all conductive carbon in the catalyst layer was 1). On the other hand, the mass of the solid polymer electrolyte is 0.85), the mass of platinum per 1 cm ² of the anode catalyst layer area on the solid polymer electrolyte membrane after transfer is 0.10 mg, and the thickness of the anode catalyst layer is 14 μm. A single cell for evaluation was assembled and evaluated in the same manner as in Example 1 except that.

  As a result of the evaluation, the voltage at the start of power generation was 0.565V, the voltage after continuous operation for 500 hours was 0.468V, and the voltage maintenance rate was 82.8%.

[Example 14]
4.5 g of catalyst-supporting carbon (platinum content 29% by weight) in which platinum is supported as a catalyst on Ketjen Black EC (G band half-value width: 68 cm ⁻¹ ), Ketjen Black EC600JD (manufactured by Ketjen Black International) Is a catalyst-supported carbon (platinum content 29 wt%) in which platinum is supported as a catalyst on carbon (G band half-value width: 31 cm ⁻¹ ) whose crystallinity has been increased by heat treatment at 2800 ° C. in a nitrogen atmosphere. 5 g, 0.39 g of carbon (G band half-value width: 31 cm ⁻¹ ) that has been crystallized by heat-treating Ketjen Black EC600JD at 2800 ° C. in a nitrogen atmosphere, solid polymer electrolyte dispersion (Nafion manufactured by DuPont) Dispersion DE520, electrolyte content 5% by weight) 55.2 g (total conductivity in catalyst layer) In a glass container in a water bath set to hold 12.5 g of pure polymer electrolyte and 12.5 g of pure water and 5 g of 2-propanol at 25 ° C. The resulting mixture was dispersed for 3 hours to obtain an anode catalyst layer ink.

Ketjen Black EC (G band half-width: 68 cm ⁻¹ ) platinum supported on a catalyst (platinum content 49 wt%) 4.5 g, and Ketjen Black EC600JD at 2800 ° C. in a nitrogen atmosphere. 0.5 g of catalyst-supported carbon (platinum content 49% by weight) in which platinum is supported as a catalyst on carbon (G band half-width: 31 cm ⁻¹ ) which has been improved in crystallinity by heat treatment, and ketjen black EC600JD in a nitrogen atmosphere Below, 0.28 g of carbon (G band half-width: 31 cm ⁻¹ ) increased by heat treatment at 2800 ° C., solid polymer electrolyte dispersion (Nafion dispersion DE520, electrolyte content 5 wt%) 2 g (the mass of the solid polymer electrolyte is 0.85 with respect to 1 of the total conductive carbon in the catalyst layer), pure 12.5 g, 2-propanol 5g, with a glass vessel in a water bath set to hold at 25 ° C., by 3 hours mixed and dispersed using a homogenizer to obtain a catalyst layer ink for the cathode side.

  Except for using the catalyst layer ink for the anode side and the catalyst layer ink for the cathode side, the thickness of the anode catalyst layer was 11 μm, and the thickness of the anode catalyst layer was 13 μm. A single cell for evaluation was assembled and evaluated.

  As a result of the evaluation, the voltage at the start of power generation was 0.582 V, the voltage after continuous operation for 500 hours was 0.494 V, and the voltage maintenance rate was 84.9%.

[Example 15]
In the preparation of the anode-side catalyst layer ink and the cathode-side catalyst layer ink, instead of carbon obtained by heat-treating Ketjen Black EC600JD, Vulcan XC72R (manufactured by CABOT) was heat-treated at 2800 ° C. in a nitrogen atmosphere. A single cell for evaluation was assembled and evaluated in the same manner as in Example 14 except that carbon having improved properties (G band half-width: 35 cm ⁻¹ ) was used.

  The evaluation results were a power generation start voltage of 0.583 V, a 500 hour continuous operation voltage of 0.493 V, and a voltage maintenance ratio of 84.6%.

[Example 16]
In preparing the anode-side catalyst layer ink and the cathode-side catalyst layer ink, instead of carbon obtained by heat-treating Ketjen Black EC600JD, Black Pearl 2000 (manufactured by CABOT) was heat-treated at 2800 ° C. in a nitrogen atmosphere. A single cell for evaluation was assembled and evaluated in the same manner as in Example 14 except that carbon (G band half-width: 39 cm ⁻¹ ) with increased crystallinity was used.

  As a result of the evaluation, the voltage at the start of power generation was 0.572 V, the voltage after continuous operation for 500 hours was 0.484 V, and the voltage maintenance rate was 84.6%.

[Example 17]
In preparation of the anode-side catalyst layer ink and the cathode-side catalyst layer ink, instead of carbon obtained by heat-treating ketjen black EC600JD, highly crystalline acetylene black (G band half-width: G-band produced from acetylene as a raw material) A single cell for evaluation was assembled and evaluated in the same manner as in Example 14 except that 45 cm ⁻¹ ; manufactured by Denki Kagaku Kogyo) was used.

  The evaluation results were a power generation start voltage of 0.579 V, a 500 hour continuous operation voltage of 0.492 V, and a voltage maintenance rate of 85.0%.

[Example 18]
4.5 g of catalyst-supporting carbon (platinum content 29% by weight) in which platinum is supported as a catalyst on Ketjen Black EC (G band half-width: 68 cm ⁻¹ ), catalyst-supporting carbon in which platinum is supported as a catalyst on carbon nanotubes (Platinum content 29% by weight) 0.5 g, carbon nanotube 0.39 g, solid polymer electrolyte dispersion (Nafion dispersion DE520, electrolyte content 5% by weight) 55.2 g (mass of all conductive carbon in the catalyst layer 1 The solid polymer electrolyte mass is 0.70), 12.5 g of pure water, and 5 g of 2-propanol are mixed in a glass container in a water bath set at 25 ° C. for 3 hours using a homogenizer. Dispersion gave an anode catalyst layer ink.

4.5 g of catalyst-carrying carbon (platinum content 49% by weight) in which platinum is supported as a catalyst on Ketjen Black EC (G band half-width: 68 cm ⁻¹ ), and catalyst-carrying carbon in which platinum is supported as a catalyst on carbon nanotubes (Platinum content 49 wt%) 0.5 g, carbon nanotubes 0.28 g, solid polymer electrolyte dispersion (Nafion dispersion DE520, electrolyte content 5 wt%) 48.2 g (mass of all conductive carbon in the catalyst layer 1 The solid polymer electrolyte mass was 0.85), pure water 12.5 g, and 2-propanol 5 g were mixed for 3 hours using a homogenizer in a glass container in a water bath set to hold at 25 ° C. By dispersing, a cathode catalyst layer ink was obtained.

  Except for using the catalyst layer ink for the anode side and the catalyst layer ink for the cathode side, the thickness of the anode catalyst layer was 11 μm, and the thickness of the anode catalyst layer was 13 μm. A single cell for evaluation was assembled and evaluated.

  The evaluation results were a power generation start voltage of 0.588 V, a 500 hour continuous operation voltage of 0.483 V, and a voltage maintenance ratio of 82.1%.

[Example 19]
4.5 g of catalyst-supporting carbon (platinum content 28 wt%) supporting platinum as a catalyst on Ketjen Black EC (G band half-width: 68 cm ⁻¹ ), catalyst-supporting carbon supporting platinum as a catalyst on carbon nanohorn (Platinum content 28% by weight) 0.5 g, carbon nanohorn 0.4 g, solid polymer electrolyte dispersion (Nafion dispersion DE520, electrolyte content 5% by weight) 56.0 g (mass of all conductive carbon in the catalyst layer 1 The solid polymer electrolyte mass is 0.70), 12.5 g of pure water, and 5 g of 2-propanol are mixed in a glass container in a water bath set at 25 ° C. for 3 hours using a homogenizer. Dispersion gave an anode catalyst layer ink.

4.5 g of catalyst-supporting carbon (platinum content 49% by weight) in which platinum is supported as a catalyst on Ketjen Black EC (G band half-width: 68 cm ⁻¹ ), and catalyst-supporting carbon in which platinum is supported as a catalyst on carbon nanohorn (Platinum content 49 wt%) 0.5 g, carbon nanohorn 0.28 g, solid polymer electrolyte dispersion (Nafion dispersion DE520, electrolyte content 5 wt%) 48.2 g (mass of all conductive carbon in the catalyst layer 1 The solid polymer electrolyte mass was 0.85), pure water 12.5 g, and 2-propanol 5 g were mixed for 3 hours using a homogenizer in a glass container in a water bath set to hold at 25 ° C. By dispersing, a cathode catalyst layer ink was obtained.

  Except for using the catalyst layer ink for the anode side and the catalyst layer ink for the cathode side, the thickness of the anode catalyst layer was 11 μm, and the thickness of the anode catalyst layer was 13 μm. A single cell for evaluation was assembled and evaluated.

  As a result of the evaluation, the voltage at the start of power generation was 0.585 V, the voltage after continuous operation for 500 hours was 0.496 V, and the voltage maintenance rate was 84.8%.

[Example 20]
4.5g of catalyst-supporting carbon (platinum content 28% by weight) in which platinum is supported as a catalyst on ketjen black EC (G band half-width: 68 cm ^-1 ), vapor-grown carbon fiber (VGCF; Showa Denko) Catalyst-supported carbon carrying platinum as a catalyst (platinum content 28 wt%) 0.5 g, VGCF 0.4 g, solid polymer electrolyte dispersion (manufactured Nafion dispersion DE520, electrolyte content 5 wt%) 56.0 g (catalyst In a glass container in a water bath set so as to hold 12.5 g of pure water and 5 g of 2-propanol at 25 ° C. with respect to the mass 1 of all conductive carbon in the layer. The anode side catalyst layer ink was prepared by mixing and dispersing for 3 hours using a homogenizer.

4.5 g of catalyst-carrying carbon (platinum content 49% by weight) in which platinum is supported as a catalyst on Ketjen Black EC (G band half-width: 68 cm ⁻¹ ), and catalyst-carrying carbon in which platinum is supported as a catalyst in VGCF ( Platinum content 49 wt%) 0.5 g, VGCF 0.28 g, solid polymer electrolyte dispersion (Nafion dispersion DE 520, electrolyte content 5 wt%) 48.2 g (based on mass 1 of all conductive carbon in the catalyst layer) The solid polymer electrolyte mass is 0.85), 12.5 g of pure water, and 5 g of 2-propanol are mixed and dispersed for 3 hours using a homogenizer in a glass container in a water bath set to be kept at 25 ° C. Thus, a cathode catalyst layer ink was obtained.

  Except for using the catalyst layer ink for the anode side and the catalyst layer ink for the cathode side, the thickness of the anode catalyst layer was 11 μm, and the thickness of the anode catalyst layer was 13 μm. A single cell for evaluation was assembled and evaluated.

  As a result of the evaluation, the voltage at the start of power generation was 0.572 V, the voltage after continuous operation for 500 hours was 0.490 V, and the voltage maintenance rate was 85.7%.

[Comparative Example 1]
In the preparation of the anode catalyst layer ink of Example 1-1 (1-1), a catalyst-supporting carbon having a platinum content of 13% by weight was used, and 81.8 g of the solid polymer electrolyte dispersion (the amount of all conductive carbon in the catalyst layer). A single cell for evaluation was assembled and evaluated in the same manner as in Example 1 except that the mass of the solid polymer electrolyte was 0.94) with respect to the mass of 1.

  As a result of the evaluation, the voltage at the start of power generation was 0.578 V, the voltage after continuous operation for 500 hours was 0.436 V, and the voltage maintenance rate was 75.4%.

[Comparative Example 2]
In the preparation of the anode catalyst layer ink of (1-1) of Example 1, 25.6 g of the solid polymer electrolyte dispersion (the solid polymer electrolyte mass was 0.1 with respect to the total conductive carbon mass 1 in the catalyst layer). A single cell for evaluation was assembled and evaluated in the same manner as in Example 1 except for 36).

  The evaluation results were a power generation start voltage of 0.569 V, a 500 hour continuous operation voltage of 0.417 V, and a voltage maintenance rate of 73.3%.

[Comparative Example 3]
In the preparation of the cathode catalyst layer ink of (1-1) of Example 1, 62.7 g of the solid polymer electrolyte dispersion (the solid polymer electrolyte mass is 1.23 with respect to the carbon mass 1 in the catalyst-supporting carbon). A single cell for evaluation was assembled and evaluated in the same manner as in Example 1 except that.

  As a result of the evaluation, the voltage at the start of power generation was 0.586 V, the voltage after continuous operation for 500 hours was 0.430 V, and the voltage maintenance rate was 73.4%.

[Comparative Example 4]
In the preparation of the cathode catalyst layer ink of (1-1) of Example 1, 33.2 g of the solid polymer electrolyte dispersion (the mass of the solid polymer electrolyte was 0.1 with respect to the mass 1 of the total conductive carbon in the catalyst layer). An evaluation unit cell was assembled and evaluated in the same manner as in Example 1 except that 65).

  The evaluation results were a power generation start voltage of 0.577 V, a voltage after continuous operation for 500 hours of 0.430 V, and a voltage maintenance ratio of 74.5%.

[Comparative Example 5]
In the preparation of the cathode catalyst layer ink of (1-1) in Example 1, a catalyst-supported carbon (platinum content 29% by weight) in which platinum is supported as a catalyst on Ketjen Black EC (G band half-value width: 68 cm ⁻¹ ). ), And the solid polymer electrolyte dispersion is 61.1 g (the mass of the solid polymer electrolyte is 0.86 with respect to the mass of all conductive carbon in the catalyst layer is 0.86), and further on the solid polymer electrolyte membrane after transfer A single cell for evaluation was assembled and evaluated in the same manner as in Example 1 except that the platinum mass per 1 cm ² of catalyst layer was 0.41 mg.

  As a result of the evaluation, the voltage at the start of power generation was 0.562 V, the voltage after continuous operation for 500 hours was 0.398 V, and the voltage maintenance rate was 70.8%.

[Comparative Example 6]
In the preparation of the anode catalyst layer ink of (1-1) in Example 1, a catalyst-supporting carbon (platinum content: 49% by weight) in which platinum was supported as a catalyst on Ketjen Black EC (G band half-width: 68 cm ⁻¹ ). ), And the solid polymer electrolyte dispersion is 43.9 g (the mass of the solid polymer electrolyte is 0.86 with respect to the mass of all conductive carbon in the catalyst layer is 0.86), and further on the solid polymer electrolyte membrane after transfer A single cell for evaluation was assembled and evaluated in the same manner as in Example 1 except that the platinum mass per 1 cm ² of the catalyst layer was 0.14 mg.

  The evaluation results were a power generation start voltage of 0.587 V, a 500 hour continuous operation voltage of 0.458 V, and a voltage maintenance ratio of 78.0%.

[Conventional example 1]
In the preparation of the anode catalyst layer ink of (1-1) in Example 1, a catalyst-supporting carbon (platinum content: 49% by weight) in which platinum was supported as a catalyst on Ketjen Black EC (G band half-width: 68 cm ⁻¹ ). ), And the solid polymer electrolyte dispersion is 50.4 g (the mass of the solid polymer electrolyte is 0.86 with respect to the mass of all conductive carbon in the catalyst layer is 0.86), and further on the solid polymer electrolyte membrane after transfer A single cell for evaluation was assembled and evaluated in the same manner as in Example 1 except that the platinum mass per 1 cm ² of the catalyst layer was 0.40 mg.

  As a result of the evaluation, the power generation start voltage was 0.590 V, the voltage after continuous operation for 500 hours was 0.487 V, and the voltage maintenance rate was 82.5%.

  From Examples 1 to 20 and Comparative Examples 1 to 6, the MEA for fuel cell of the present invention has the catalyst content in the catalyst-supporting carbon and the mass of the solid polymer electrolyte in the anode and cathode side catalyst layers within appropriate ranges. It became clear that the durability was excellent by setting. In addition, from Examples 1 to 20 and Conventional Example 1, it became clear that the MEA for fuel cells of the present invention exhibits the same durability and power generation performance even when the amount of catalyst in the anode side catalyst layer is reduced.

Claims (29)

In a fuel cell MEA in which a cathode catalyst layer and an anode catalyst layer including a catalyst-supported carbon in which a catalyst is supported on conductive carbon and a solid polymer electrolyte are disposed opposite to both surfaces of the solid polymer electrolyte membrane, ,
A ratio of the thickness of the anode catalyst layer to the cathode catalyst layer is 0.7 to 1.3;
The mass of the catalyst per unit area of the anode catalyst layer with respect to the mass of the catalyst per unit area of the cathode catalyst layer is 1/2 or less by mass ratio.
A fuel cell MEA.   2. The fuel cell according to claim 1, wherein a content ratio of the catalyst in the catalyst-supported carbon in the anode catalyst layer is smaller than a content ratio of the catalyst in the catalyst-supported carbon in the cathode catalyst layer. MEA.   The content of the catalyst in the catalyst-supported carbon in the anode catalyst layer is 8% by weight or more and 35% by weight or less, and the content of the catalyst in the catalyst-supported carbon in the cathode catalyst layer exceeds 35% by weight. 3. The MEA for fuel cell according to claim 1, wherein the MEA is 70% by weight or less.   The MEA for a fuel cell according to any one of claims 1 to 3, wherein the anode catalyst layer further includes conductive carbon on which the catalyst is not supported.   5. The fuel cell MEA according to claim 4, wherein the conductive carbon on which the catalyst is not supported contains at least carbon black.   6. The fuel cell MEA according to claim 5, wherein the carbon black includes at least one selected from the group consisting of ketjen black EC, ketjen black EC600JD, Vulcan XC72R, and black pearl 2000.   7. The fuel cell MEA according to claim 5, wherein the conductive carbon on which the catalyst is not supported contains the heat-treated carbon black. 8. The fuel cell MEA according to claim 7, wherein the heat-treated carbon black has a G-band half-value width obtained from a Raman spectrum of 55 cm ⁻¹ or less.   6. The MEA for a fuel cell according to claim 5, wherein the carbon black includes one produced from acetylene as a raw material. 10. The fuel cell MEA according to claim 9, wherein the carbon black produced using acetylene as a raw material has a G band half-value width obtained from a Raman spectrum of 55 cm ⁻¹ or less.   The fuel according to any one of claims 4 to 10, wherein the conductive carbon on which the catalyst is not supported contains at least one selected from the group consisting of carbon nanotubes, carbon nanohorns, and carbon nanofibers. MEA for batteries.   The conductive carbon on which the catalyst is not supported is contained in an amount of 5 to 80% by weight with respect to the total mass of the conductive carbon contained in the anode catalyst layer. 2. MEA for fuel cell according to   The mass of the solid polymer electrolyte in the anode catalyst layer is 0.4 to 0.9 with respect to the total mass 1 of conductive carbon contained in the anode catalyst layer, and the solid polymer electrolyte in the cathode catalyst layer 13. The fuel cell MEA according to claim 1, wherein the mass of the electrolyte is 0.6 to 1.2 with respect to the total mass 1 of the conductive carbon contained in the cathode catalyst layer. .   The conductive carbon similar to the conductive carbon on which the catalyst is not supported is contained in the conductive carbon in the catalyst-supported carbon in the anode catalyst layer in an amount of 5% by weight or more. A fuel cell MEA according to claim 1.   The MEA for a fuel cell according to any one of claims 1 to 14, wherein the cathode catalyst layer further includes carbon black heat-treated as conductive carbon on which the catalyst is not supported.   16. The fuel cell MEA according to claim 15, wherein the carbon black includes at least one selected from the group consisting of ketjen black EC, ketjen black EC600JD, Vulcan XC72R, and black pearl 2000. 17. The fuel cell MEA according to claim 15, wherein the heat-treated carbon black has a G-band half-value width obtained from a Raman spectrum of 55 cm ⁻¹ or less.   18. The fuel cell MEA according to claim 1, wherein the cathode catalyst layer further includes carbon black produced using acetylene as a raw material as conductive carbon on which a catalyst is not supported. 19. The fuel cell MEA according to claim 18, wherein the carbon black produced using acetylene as a raw material has a G band half-value width obtained from a Raman spectrum of 55 cm ⁻¹ or less.   20. The cathode catalyst layer according to claim 1, further comprising at least one selected from the group consisting of carbon nanotubes, carbon nanohorns, and carbon nanofibers as conductive carbon on which no catalyst is supported. 20. MEA for fuel cells in any one.   The conductive carbon on which the catalyst is not supported is contained in an amount of 5 to 20% by weight with respect to the total mass of the conductive carbon contained in the cathode catalyst layer. 2. MEA for fuel cell according to   The fuel cell according to any one of claims 1 to 21, wherein the conductive carbon in the catalyst-supporting carbon includes at least one selected from the group consisting of carbon nanotubes, carbon nanohorns, and carbon nanofibers. MEA.   The conductive carbon similar to the conductive carbon on which the catalyst is not supported is contained in the conductive carbon in the catalyst-supported carbon in the cathode catalyst layer in an amount of 5% by weight or more. A fuel cell MEA according to claim 1.   The fuel cell MEA according to any one of claims 1 to 23, wherein the catalyst contains at least platinum.   The fuel cell MEA according to any one of claims 1 to 24, wherein the catalyst is an alloy of platinum and other metals.   26. The fuel cell MEA according to claim 1, wherein the cathode catalyst layer contains at least a polymer containing a fluorine atom.   27. The polymer containing a fluorine atom is at least one polymer selected from the group consisting of polytetrafluoroethylene, polyhexafluoropropylene, and tetrafluoroethylene-hexafluoropropylene copolymer. MEA for fuel cell.   A fuel cell comprising the fuel cell MEA according to claim 1.   A vehicle comprising the fuel cell according to claim 28.