JP2006294267A - Catalyst ink for fuel cell electrode formation - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide catalyst ink for fuel cell electrode formation, which can enhance a mechanical strength of an electrode catalyst layer. <P>SOLUTION: In the catalyst ink for fuel cell electrode formation which contains an electrolyte and a solvent, a polar solvent with a relative dielectric constant of 25 or more and 50 or less at a temperature of 20°C is used as the above solvent, and a molecular chain is formed when a surface of colloidal particles of an electrolyte polymer dispersed/suspended in the catalyst in a partially colloidal state is melted and the electrolyte molecular chain intertwines well with an electrolyte film 2 and as a result, the catalyst layers (3a, 3b) and the electrolyte layer 2 are firmly bonded to create a sufficient mechanical strength. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a catalyst ink for forming a fuel cell electrode, an electrolyte membrane-electrode assembly having an electrode catalyst layer produced using the ink, a method for producing an electrolyte membrane-electrode assembly, and the electrolyte membrane-electrode assembly. The present invention relates to a fuel cell used and a vehicle equipped with the fuel cell. More specifically, a catalyst ink for forming a fuel cell electrode capable of improving the mechanical characteristics of the electrode catalyst layer, an electrolyte membrane-electrode assembly having an electrode catalyst layer produced using the ink, and an electrolyte membrane-electrode assembly The present invention relates to a manufacturing method, a fuel cell using the electrolyte membrane-electrode assembly, and an automobile equipped with the fuel cell.

  In recent years, in response to social demands and trends against the background of energy and environmental problems, fuel cells that can operate at room temperature and obtain high output density have attracted attention as power sources for electric vehicles and stationary power sources. 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 an electrolyte 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 a catalyst component is supported on a conductive carrier and a solid polymer electrolyte.

  FIG. 1 is a schematic cross-sectional view for illustrating an example of a polymer electrolyte fuel cell. In FIG. 1, a polymer electrolyte fuel cell 1 includes an anode side electrode catalyst layer 3a and an anode side gas diffusion layer 4a, a cathode side electrode catalyst layer 3b and a cathode side gas diffusion layer on both sides of a solid polymer electrolyte membrane 2. 4b has an MEA 5 disposed so as to face each other, and the MEA 5 is further sandwiched between an anode side separator 6a and a cathode side separator 6b. Further, the fuel gas and the oxidant gas supplied to the MEA 5 are supplied to the anode side separator 6a and the cathode side separator 6b through gas supply grooves 7a and 7b provided at a plurality of locations, respectively.

  In the polymer electrolyte fuel cell, the following electrochemical reaction proceeds. First, hydrogen contained in the fuel gas supplied to the anode side is oxidized by the catalyst component to become protons and electrons. Next, the generated protons pass through the solid polymer electrolyte contained in the electrode catalyst layer and the solid polymer electrolyte membrane in contact with the electrode catalyst layer, and reach the cathode side electrode catalyst layer. In addition, the electrons generated in the anode-side electrode catalyst layer include the conductive carrier constituting the electrode catalyst layer, the gas diffusion layer in contact with the side of the electrode catalyst layer different from the solid polymer electrolyte membrane, the separator, and the outside. The cathode side electrode catalyst layer is reached through the circuit. The protons and electrons that have reached the cathode-side electrode catalyst layer react with oxygen contained in the oxidant gas supplied to the cathode side to generate water. In the fuel cell, electricity can be taken out through the above-described electrochemical reaction.

As for the material of each constituent member of the electrolyte membrane-electrode assembly (MEA), perfluorocarbon sulfonic acid (for example, Nafion (registered trademark) membrane manufactured by Du Pont, USA) is generally used as the polymer electrolyte membrane. Is used. As the gas diffusion layer, for example, carbon paper subjected to water repellent treatment is used. Further, a catalyst ink is used for the electrode catalyst layer. As the catalyst ink, an electrode catalyst in which a catalyst component is usually supported on the surface of a conductive material such as Pt-supported carbon fine particles and a fluorine-based fluorine catalyst having proton conductivity. A material in which an electrolyte such as a polymer is dispersed in water, a solvent of a lower alcohol such as cyclohexanol, ethanol, or 2-propanol is used. Conventionally, an electrode catalyst layer is formed by directly applying such a catalyst ink to a polymer electrolyte membrane and then drying. Alternatively, such a catalyst ink is applied to a transfer mount and dried to form an electrode catalyst layer, and then the electrode catalyst layer is transferred to the polymer electrolyte membrane by hot pressing to produce an MEA. (For example, see Patent Document 1). In the above-mentioned Patent Document 1, since film formation can be performed at a relatively low temperature, an electrode catalyst layer is formed using a catalyst ink in which Nafion (electrolyte polymer) is dispersed / suspended in a lower alcohol as in the prior art. Yes.
Japanese Patent Publication No. 5-507583

  However, in the method of Patent Document 1, the electrolyte polymer is not completely dissolved in the solvent, but is partially dispersed / suspended in the solvent in a colloidal form. When an electrocatalyst layer is produced by evaporating lower alcohol from such a dispersion / suspension, colloid remains on the membrane surface, so the intermolecular bond of the electrolyte polymer is weak and the mechanical strength of the electrocatalyst layer is reduced. Resulting in. Such a decrease in the mechanical strength of the electrode catalyst layer is continuously operated in applications other than automobiles such as stationary generators, so that the pores in the electrode catalyst layer are not collapsed and the porous structure is maintained. Therefore, it will not be a problem. However, in automotive applications in which system start / stop and output fluctuations frequently occur, the mechanical strength of the electrode catalyst layer is regarded as a problem, and pores in the catalyst layer collapse due to frequent start / stop and output fluctuations. The passage of gas (fuel gas or oxidant gas) in the pores becomes poor, and movement (deformation) of the electrolyte polymer occurs during the drying / wetting cycle of the polymer electrolyte membrane. As a result, especially on the cathode side where the wet and dry changes are drastically due to changes in the amount of water produced due to fluctuations in output, the porous structure of the electrode catalyst layer in the initial state collapses, the porosity decreases, and the amount of reactant gas supplied to the electrode catalyst layer As a result, the gas diffusibility of the electrode catalyst layer decreases when the system is started / stopped or the output is fluctuated even though automobiles are required to maintain power generation performance over a long period of 5000 hours. As a result, there arises a problem that the output of the fuel cell is reduced.

  Accordingly, the present invention has been made in consideration of the above circumstances, and an object thereof is to provide a fuel cell electrode forming catalyst ink capable of improving the mechanical strength of an electrode catalyst layer.

  Another object of the present invention is to provide a catalyst ink for forming a fuel cell electrode that can suppress / prevent a decrease in the porosity of an electrode catalyst layer even if start / stop cycles and output fluctuation cycles occur frequently over a long period of time. .

  Another object of the present invention is to provide an electrolyte membrane-electrode assembly capable of improving the mechanical strength of the electrode catalyst layer and a method for producing the same.

  Another object of the present invention is to provide an electrolyte membrane-electrode assembly capable of suppressing / preventing a decrease in the porosity of the electrode catalyst layer even if start / stop cycles and output fluctuation cycles occur frequently over a long period of time, and a method for producing the same. That is.

  Still another object of the present invention is to provide a fuel cell that can suppress a decrease in output (maintain power generation performance) even with respect to start / stop cycles and output fluctuation cycles that occur frequently over a long period of time.

  In recent years, the catalyst performance has been improved and improved until a sufficient catalytic activity can be achieved. Therefore, in order to achieve the above-mentioned objects, the present inventor is not concerned with the catalyst performance that has been focused on in the past. The investigation was conducted focusing on the other requirements of the catalyst layer, particularly the mechanical strength of the electrode catalyst layer. As a result, by using a polar solvent having a specific dielectric constant as the solvent of the catalyst ink, the electrolyte can be completely dissolved in the solvent, and the electrode catalyst layer is formed by dissolving the electrolyte in such a solvent. When formed, the catalyst layer has no colloid, and the membrane can be formed in a state where the molecular chains of the electrolyte polymer are strongly entangled. Therefore, the electrode catalyst layer formed in such a solution state has sufficient mechanical strength. I found out that I can demonstrate it. In addition, the present inventor formed an electrode catalyst layer using such a polar solvent and conducted a start / stop durability test over a long period of time. As a result, the porous structure of the electrode catalyst layer collapsed (decrease in porosity). From now on, if an electrolyte membrane-electrode assembly using such an electrode catalyst layer is used as a fuel cell, a decrease in catalytic activity is not observed even in long-term use. It has also been found that it can be sufficiently used for the use of

  Further, the inventor of the present invention, even in the case of an electrode catalyst layer formed using a lower alcohol as a solvent for the catalyst ink in the same manner as in the prior art, the electrode catalyst layer is previously formed before joining the electrolyte membrane and the electrode catalyst layer. When infiltrated in a polar solvent having the above specific dielectric constant and then joined to the electrolyte membrane, the surface of the colloidal particles existing in the electrode catalyst layer melts, and this molecular chain and the molecular chain of the electrolyte constituting the electrolyte membrane And the electrode catalyst layer and the electrolyte membrane can be firmly bonded, and the molecular chain of the colloidal particles present in the electrode catalyst layer and the molecular chain of the electrolyte in the catalyst layer are entangled well. As described above, the electrode catalyst layer can exhibit sufficient mechanical strength, and even in the start / stop durability test over a long period of time, the porous structure of the electrode catalyst layer collapses (decrease in porosity). Significantly suppressed and prevented Therefore, when such an electrode catalyst layer is used for a fuel cell of an electrolyte membrane-electrode assembly, it has also been found that the fuel cell performance can be maintained over a long period of time without reducing the catalytic activity as described above. .

  Based on the above findings, the present invention has been completed.

  That is, the above objects are characterized in that in the catalyst ink for forming a fuel cell electrode containing an electrode catalyst, an electrolyte and a solvent, a polar solvent having a relative dielectric constant at 20 ° C. of 25 to 50 is used as the solvent. Achieved with a catalyst ink.

  The above-mentioned objects are also obtained by infiltrating a polar solvent having a relative dielectric constant of 25 or more and 50 or less at 20 ° C. into an electrode catalyst layer formed on a transfer mount, and then subjecting the electrode catalyst layer to a solid polymer electrolyte membrane. It can also be achieved by a method for producing an electrolyte membrane-electrode assembly, which has a process of transferring to an electrolyte.

  The above objects are also obtained by forming an electrode catalyst layer on the surface of the gas diffusion layer to produce an electrode catalyst layer-gas diffusion layer assembly, and then subjecting the electrode catalyst layer-gas diffusion layer assembly to a relative dielectric at 20 ° C. This is also achieved by a method for producing an electrolyte membrane-electrode assembly, which comprises a step of infiltrating a polar solvent having a rate of 25 or more and 50 or less and then joining with a solid polymer electrolyte membrane.

  According to the present invention, since a polar solvent having a relative dielectric constant of 25 to 50 at 20 ° C. is used as a solvent constituting the catalyst ink, the electrolyte can be formed in a state dissolved in the solvent. The molecular chains of the electrolyte polymer are regularly entangled in a certain direction, and the crystallinity of the electrolyte polymer in the electrode catalyst layer can be improved. For this reason, the mechanical strength of such an electrode catalyst layer is improved, and a decrease in the porosity of the electrode catalyst layer due to a long-term start / stop cycle and an output fluctuation cycle can be prevented. Therefore, a fuel cell having an electrolyte membrane-electrode assembly using such an electrode catalyst layer can effectively prevent a decrease in output.

  Further, according to the method of the present invention, an electrode catalyst layer formed using a lower alcohol as a solvent for the catalyst ink in the same manner as in the prior art has a relative dielectric constant of 25 in advance at 20 ° C. before joining with the electrolyte membrane. By infiltrating in a polar solvent of 50 or less, the surface of the colloid existing in the electrode catalyst layer is dissolved, and the molecular chains of the colloid particles existing in the electrode catalyst layer and the molecular chains of the electrolyte in the catalyst layer are dissolved. And the electrocatalyst layer can improve the mechanical strength, and at the same time, the molecular chains of the electrolyte polymer in the colloidal surface can be tightly bound (entangled) with the molecular chains of the electrolyte polymer. An MEA having excellent properties, that is, an electrode catalyst layer and a solid polymer electrolyte membrane that are firmly bonded can be produced. Therefore, even when a fuel cell using such an MEA is used for a long period of time, the catalytic activity does not decrease and the output does not decrease. The method of the present invention is also very useful industrially in that the conventional method for forming an electrode catalyst layer constructed with a conventional catalyst ink using an alcohol solvent can be applied as it is.

  Further, since the electrode catalyst layer according to the present invention does not decrease the catalytic activity even when used for a long period of time, even if the start / stop cycle and the output fluctuation cycle occur frequently for a long time, the output decrease is suppressed. A fuel cell can be manufactured. For this reason, the fuel cell of the present invention can be used particularly suitably for applications in which start / stop cycles and output fluctuation cycles occur frequently, such as fuel cells for automobiles.

  Hereinafter, the present invention will be described in detail.

  The first aspect of the present invention is a catalyst ink for forming a fuel cell electrode containing an electrode catalyst, an electrolyte and a solvent, and a polar solvent having a relative dielectric constant at 20 ° C. of 25 to 50 as the solvent (in this specification, simply “ The catalyst ink is also characterized in that a “polar solvent” is also used. Thus, instead of using water or lower alcohols in the past, a polar solvent having a specific dielectric constant was used because the solvent was an electrolyte, particularly an electrolyte polymer such as perfluorocarbon sulfonic acid. Can be completely dissolved without forming a colloid. Therefore, when the electrocatalyst layer is formed using the catalyst ink prepared in such a solution state, there is no weak bond between the colloid particles, This is because a membrane can be formed in a strong state in which the molecular chains of the electrolyte polymer are well entangled, and an electrode catalyst layer having excellent mechanical strength can be formed. In addition, since the polar solvent having a specific dielectric constant has a relatively high boiling point, the polar solvent evaporates more slowly than the conventional ink when the catalyst ink of the present invention is applied to form a film. Since crystallization can be promoted, an electrode catalyst layer having excellent mechanical strength can be formed also in this respect. In the present specification, “crystallization” means that the polymer chains are entangled in a direction having a certain regularity, and the polymer chains are strongly entangled with a certain directionality. Increases mechanical strength. On the other hand, in the conventional electrode catalyst layer using a low boiling point solvent such as lower alcohol, the solvent is rapidly evaporated during the film forming process, and the amorphous state electrode in which polymer chains are randomly entangled It becomes a catalyst layer. For this reason, the conventional electrode catalyst layer is inferior in mechanical strength. As described above, since the electrode catalyst layer according to the present invention has excellent mechanical strength, the porous structure can be maintained without collapsing the pores even if the start / stop cycle and the output fluctuation cycle are performed over a long period of time. If an electrolyte membrane-electrode assembly using such an electrode catalyst layer is made into a fuel cell, the reaction gas can sufficiently pass through the pores in the electrode catalyst layer even after being used for a long time, and a decrease in catalyst activity is recognized. The fuel cell can be used for a long time.

  In the present invention, the relative permittivity of the polar solvent at 20 ° C. is 25 or more and 50 or less. At this time, when the relative dielectric constant is less than 25, the polarity of the solvent molecules becomes too small to sufficiently dissolve the electrolyte, and a colloid is formed in the electrode catalyst layer, and the above-described effects are sufficiently exhibited. Can not. On the other hand, if the relative permittivity of the polar solvent exceeds 50, the boiling point of the solvent becomes too high, and the temperature for evaporating the solvent during the formation of the electrode catalyst layer becomes too high, which is industrially commensurate. In addition, when the catalyst ink is applied on the electrolyte membrane, the electrolyte membrane is damaged due to the high temperature treatment. More preferably, it is 30 or more and 50 or less.

  The polar solvent having a relative dielectric constant at 20 ° C. of 25 or more and 50 or less used in the present invention is not particularly limited as long as it satisfies the above-mentioned relative dielectric constant. For example, a polar solvent having a boiling point of 150 to 250 ° C. Are preferably used. When the boiling point is in such a range, the polar solvent slowly evaporates under the conditions for forming the electrode catalyst layer, which will be described in detail below, so that the crystallization of the film can be promoted. It becomes a layer with excellent mechanical strength.

  The polar solvent preferably used in the present invention is not particularly limited as long as it has a relative dielectric constant of 25 or more and 50 or less. Specifically, DMSO (dimethyl sulfoxide) (relative dielectric constant 46.7), DMAc (Dimethylacetamide) (relative permittivity 37.8), NMP (N-methyl-2-pyrrolidinone) (relative permittivity 32.0), EG (ethylene glycol) (relative permittivity 38.7 to 40.0), Examples thereof include DMF (N, N-dimethylformamide) (relative permittivity 36.7) and glycerin (relative permittivity 42.5). Among these, considering the pore structure of the electrode catalyst layer to be formed, ease of handling, electrolyte solubility, etc., DMSO and NMP are particularly preferably used, and DMSO is particularly preferred. These solvents may be used alone or in the form of a mixture of two or more.

  The amount of the polar solvent used in the present invention is not particularly limited as long as the electrolyte can be completely dissolved, but the electrolyte is preferably 3 to 20% by mass, more preferably 5 to 10% by mass in the polar solvent. The amount is such that the concentration becomes. At this time, if the concentration of the electrolyte exceeds 20% by mass, a part of the colloid may be formed without completely dissolving the electrolyte. Conversely, if the concentration of the electrolyte is less than 3% by mass, the contained electrolytic mass If the amount is too small, the molecular chains of the electrolyte polymer may not be entangled well and the mechanical strength of the formed catalyst layer may be inferior. Moreover, in the catalyst ink, the concentration of the solid content including the electrode catalyst and the solid polymer electrolyte is preferably 8 to 50% by mass, more preferably about 10 to 20% by mass in the catalyst ink.

  The electrolyte (solid polymer electrolyte) constituting the catalyst ink of the present invention includes a fluorine-based electrolyte containing fluorine atoms in all or part of the polymer skeleton, and a hydrocarbon-based electrolyte containing no fluorine atoms in the polymer skeleton. Broadly divided.

  Specific examples of the fluorine electrolyte include perfluorocarbon sulfonic acids such as Nafion (registered trademark, manufactured by DuPont), Aciplex (registered trademark, manufactured by Asahi Kasei Co., Ltd.), and Flemion (registered trademark, manufactured by Asahi Glass Co., Ltd.). Polymer, polytrifluorostyrene sulfonic acid polymer, perfluorocarbon phosphonic acid polymer, trifluorostyrene sulfonic acid polymer, ethylene tetrafluoroethylene-g-styrene sulfonic acid polymer, ethylene-tetrafluoroethylene copolymer, polyvinylidene A preferred example is a fluoride-perfluorocarbon sulfonic acid-based polymer.

  Specific examples of the hydrocarbon electrolyte include polysulfone sulfonic acid, polyaryl ether ketone sulfonic acid, polybenzimidazole alkyl sulfonic acid, polybenzimidazole alkyl phosphonic acid, polystyrene sulfonic acid, polyether ether ketone sulfonic acid, polyphenyl. A suitable example is sulfonic acid.

  Since the solid polymer electrolyte is excellent in durability, mechanical strength and the like, it preferably contains a fluorine atom. Among them, Nafion (registered trademark, manufactured by DuPont), Aciplex (registered trademark, manufactured by Asahi Kasei Corporation), Fluorine electrolytes such as Flemion (registered trademark, manufactured by Asahi Glass Co., Ltd.) are preferred.

  The catalyst ink of the present invention contains an electrode catalyst in addition to the polar solvent and the electrolyte described above. The electrode catalyst constituting the catalyst ink of the present invention is not particularly limited as long as it has an action of catalyzing a hydrogen oxidation reaction (anode side) and an oxygen reduction reaction (cathode side). It can be used similarly. Specifically, the catalyst component is supported on a conductive carrier. In this case, the catalyst component is not particularly limited as long as it can catalyze the hydrogen oxidation reaction (anode side) and the oxygen reduction reaction (cathode side), and known catalyst components can be used in the same manner. For example, it is selected from platinum, ruthenium, iridium, rhodium, palladium, osmium, tungsten, lead, iron, chromium, cobalt, nickel, manganese, vanadium, molybdenum, gallium, aluminum and the like, and alloys thereof. In addition, the composition of the alloy in the case of using an alloy as an electrode catalyst varies depending on the type of metal to be alloyed and the like, and can be appropriately selected by a person skilled in the art. Is preferably 10 to 70 atomic%. 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. In addition, the shape and size of the catalyst component are not particularly limited, and the same shape and size as those of known catalyst components can be used. However, the catalyst component is preferably granular with an average particle diameter of 1 to 30 nm. It is preferably 1 nm or more from the viewpoint of easy loading, and preferably 30 nm or less from the viewpoint of catalyst utilization. The “average particle diameter of the catalyst” in the present invention is the average value of the crystallite diameter determined from the half-value width of the diffraction peak of the catalyst component in X-ray diffraction or the average particle diameter of the catalyst component determined from a transmission electron microscope image. Can be measured.

  In addition, the conductive carrier that can be used for the electrode catalyst is not particularly limited as long as it has a specific surface area for supporting the catalyst component in a desired dispersed state and has sufficient electronic conductivity as a current collector. It is preferable that carbon is contained as a main component. 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” 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 BET specific surface area of the conductive carrier may be a specific surface area sufficient to carry the catalyst component in a highly dispersed state, but is preferably 20 to 1600 m ² / g, more preferably 80 to 1200 m ² / g. Is good. The specific surface area, 20 m 2 / dispersibility of the catalyst component and the 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 component and a solid polymer electrolyte may fall on the contrary.

  Further, the size of the conductive carrier is not particularly limited, but from the viewpoint of controlling the ease of loading, the catalyst utilization, and the thickness of the electrode catalyst layer within an appropriate range, the average particle size is 5 to 200 nm. The thickness is preferably about 10 to 100 nm.

  In the electrode catalyst in which the catalyst component is supported on the conductive support, the supported amount of the catalyst component 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 component on the conductive support 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 loading amount is less than 10% by mass, the catalytic 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 amount of the catalyst component supported can be examined by inductively coupled plasma emission spectroscopy (ICP).

  The catalyst component can be supported on the conductive carrier by a known method. For example, known methods such as impregnation method, liquid phase reduction support method, evaporation to dryness method, colloid adsorption method, spray pyrolysis method, reverse micelle (microemulsion method) can be used. Alternatively, a commercially available electrode catalyst may be used.

  In the catalyst ink of the present invention, the electrode catalyst can be used in any amount as long as it can sufficiently exhibit the desired action, that is, the action of catalyzing the hydrogen oxidation reaction (anode side) and the oxygen reduction reaction (cathode side). , May be used. It is preferable that the electrode catalyst is present in the catalyst ink in an amount of 5 to 30% by mass, more preferably 9 to 20% by mass.

  The catalyst ink of the present invention may contain a water-repellent polymer such as polytetrafluoroethylene, polyhexafluoropropylene, and tetrafluoroethylene-hexafluoropropylene copolymer in addition to the electrode catalyst, the electrolyte, and the solvent. . Thereby, the water repellency of the obtained electrode catalyst layer can be increased, and water generated at the time of power generation can be quickly discharged. The amount of the water-repellent polymer added when the water-repellent polymer is used is not particularly limited as long as it does not interfere with the above effect of the present invention, but is preferably 0 with respect to the total mass of the catalyst ink. .1 to 2% by mass.

  Instead of the water-repellent polymer or in addition to the water-repellent polymer, the catalyst ink of the present invention may contain a thickener. The use of a thickener is effective when the catalyst ink cannot be successfully applied onto a transfer mount. The thickener that can be used in this case is not particularly limited, and a known thickener can be used. Examples thereof include glycerin, EG (ethylene glycol), and PVA (polyvinyl alcohol). The amount of the thickener added when the thickener is used is not particularly limited as long as it does not interfere with the above effect of the present invention, but is preferably 5 to 20 with respect to the total mass of the catalyst ink. % By mass.

  The catalyst ink of the present invention is not particularly limited in its preparation method as long as an electrode catalyst, an electrolyte and a solvent, and if necessary, a water-repellent polymer and / or a thickener are appropriately mixed. When the electrolyte is in a solid state or contains the polar solvent according to the present invention, the electrode catalyst, the electrolyte and the solvent are mixed in predetermined amounts. For example, a catalyst ink can be prepared by adding an electrolyte to a polar solvent, heating and stirring the mixture, dissolving the electrolyte in a polar solvent, and then adding an electrode catalyst thereto. Alternatively, the electrolyte is once dispersed / suspended in a solvent of a lower alcohol such as cyclohexanol, ethanol or 2-propanol (referred to as “other solvent”), and then the dispersion / suspension is mixed with a polar solvent. Then, the other solvent may be removed to prepare a mixed solution of the electrolyte and the polar solvent. Other solvent removal methods in this case are not particularly limited as long as the solvent can be removed efficiently, but the polar solvent of the present invention has a higher boiling point compared to the solvent. It is preferable to use and remove excess solvent. As such a method, for example, a commercially available dispersion / suspension of an electrolyte and the above polar solvent are stirred and mixed at room temperature, and then this mixed solution is heated at an appropriate temperature, for example, 50 to 90 ° C. Preferably, there is a method of evaporating excess solvent in the mixed solution by heating with a rotary evaporator at 70 to 80 ° C. At this time, the end of the heating (solvent removal step) can be easily determined by measuring the mass of the entire mixed solution, for example, when the mass of the excess solvent is known. When the amount of excess solvent is unknown, for example, the end of heating (that is, when the removal of excess solvent is completed) may be determined by, for example, observing no evaporated solvent at all. In the above method, rather than adding and dissolving the electrolyte directly in the polar solvent, the latter method in which the electrolyte is once dispersed / suspended in another solvent and then mixed with the polar solvent is more polar. An electrolyte in a solvent can be dissolved, which is preferable. Further, in this case, a commercially available electrolyte solution in which the electrolyte is previously prepared in the other solvent (for example, Nafion solution manufactured by DuPont: Nafion is dispersed / suspended at a concentration of 5 wt% in 1-propanol). May be used in the above method as is.

  The catalyst ink of the present invention may be used for only one or both of the cathode side electrode catalyst layer and the anode side electrode catalyst layer, but the cathode side is particularly affected by changes in the amount of generated water due to output fluctuations. At least the cathode-side electrode catalyst layer because there is a high risk that the porous structure of the electrode catalyst layer in the initial state collapses due to changes in dryness and moisture, the porosity decreases, and the amount of reactant gas supplied to the electrode catalyst layer decreases. It is preferably used for the electrode catalyst layer on both the cathode and anode sides. In the present invention, the catalyst ink when the catalyst ink of the present invention is not used is a catalyst ink similar to a known one, for example, water, a solvent of a lower alcohol such as cyclohexanol, ethanol or 2-propanol is used instead of the polar solvent. Except for this, the same catalyst ink as described above can be used.

  In the present invention, an electrolyte membrane-electrode assembly (MEA) can be produced by the same method as that conventionally known except that the catalyst ink of the present invention is used. For example, the catalyst ink prepared above is applied and dried on a transfer mount with a desired thickness to form an electrode catalyst layer on the cathode side and the anode side, respectively, and this electrode catalyst layer comes inside. Thus, after sandwiching the solid polymer electrolyte membrane between the electrode catalyst layers and joining them by hot pressing or the like, the transfer mount is peeled off to obtain an MEA. Therefore, the second of the present invention relates to an electrolyte membrane-electrode assembly (MEA) having an electrode catalyst layer produced using the catalyst ink of the present invention.

  Hereinafter, the preferable aspect of the manufacturing method of MEA of this invention is demonstrated. In addition, the following aspects show the preferable aspect of this invention, and the manufacturing method of MEA of this invention is not limited to the following method.

  First, the catalyst ink of the present invention is applied and dried on a transfer mount to form an electrode catalyst layer. In this case, as the transfer mount, a known sheet such as a PTFE (polytetrafluoroethylene) sheet, a PET (polyethylene terephthalate) sheet, or a polyester sheet can be used. The transfer mount is appropriately selected according to the type of catalyst ink to be used (particularly, a conductive carrier such as carbon in the ink). In the above process, the thickness of the electrode catalyst layer is not particularly limited as long as it can sufficiently exhibit the catalytic action of the hydrogen oxidation reaction (anode side) and the oxygen reduction reaction (cathode side). Thickness can be used. Specifically, the thickness of the electrode catalyst layer is 1 to 30 μm, more preferably 1 to 20 μm. The method for applying the catalyst ink onto the transfer mount is not particularly limited, and a known method such as a screen printing method, a deposition method, or a spray method can be similarly applied. Also, the drying conditions of the applied electrode catalyst layer are not particularly limited as long as the polar solvent can be completely removed from the electrode catalyst layer. Specifically, the catalyst ink coating layer (electrode catalyst layer) is dried in a vacuum dryer at room temperature to 100 ° C., more preferably 50 to 80 ° C., for 30 to 60 minutes. At this time, if the thickness of the catalyst layer is not sufficient, the coating and drying process is repeated until a desired thickness is obtained. Next, after sandwiching the solid polymer electrolyte membrane with the electrode catalyst layer thus prepared, hot pressing is performed on the laminate. At this time, the hot press conditions are not particularly limited as long as the electrode catalyst layer and the solid polymer electrolyte membrane can be sufficiently closely joined, but are 100 to 200 ° C., more preferably 110 to 170 ° C. The press pressure is preferably 1 to 5 MPa. Thereby, the bondability between the solid polymer electrolyte membrane and the electrode catalyst layer can be enhanced. After performing hot pressing, an MEA comprising an electrode catalyst layer and a solid polymer electrolyte membrane can be obtained by peeling off the transfer mount. As will be described in detail below, the MEA according to the present invention generally further includes a gas diffusion layer. At this time, the gas diffusion layer is obtained by peeling off the transfer mount in the above method. It is preferable that the joined body is further sandwiched between gas diffusion layers to further join each electrode catalyst layer after joining the electrode catalyst layer and the solid polymer electrolyte membrane. Alternatively, after an electrode catalyst layer is formed on the surface of the gas diffusion layer in advance to produce an electrode catalyst layer-gas diffusion layer assembly, the electrode catalyst layer-gas diffusion layer assembly is solid as described above. It is also preferable to sandwich and bond the polymer electrolyte membrane by hot pressing.

  Although it does not specifically limit as a solid polymer electrolyte membrane which can be used in the said method, The electrolyte enumerated in description of the electrode catalyst layer can be used similarly. Examples include Nafion manufactured by DuPont, Flemion manufactured by Asahi Glass, and Aciplex manufactured by Asahi Kasei. 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. In the present invention, the solid polymer electrolyte membrane and the electrolyte contained in the electrode catalyst layer may be the same or different, but the junction between the electrode catalyst layer and the solid polymer electrolyte membrane may be used. It is desirable to use the same one in consideration of sex.

  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 operation of the fuel cell, it is preferably 5 μm or more, and from the viewpoint of output characteristics during operation of the fuel cell, it is preferably 300 μm or less.

  At this time, the gas diffusion layer used in the MEA is not particularly limited, and a known one can be used in the same manner. For example, the conductive and porous properties such as carbon woven fabric, paper-like paper body, felt, and non-woven fabric are used. The thing which uses the sheet-like material which has as a base material etc. are mentioned. The thickness of the substrate may be appropriately determined in consideration of the characteristics of the obtained gas diffusion layer, but may be about 30 to 500 μm. If the thickness is less than 30 μm, sufficient mechanical strength or the like may not be obtained, and if it exceeds 500 μm, the distance through which gas or water permeates is undesirably increased.

  The method for forming the electrode catalyst layer on the surface of the gas diffusion layer is not particularly limited, and known methods such as a screen printing method, a deposition method, and a spray method can be similarly applied. In addition, the conditions for forming the electrode catalyst layer on the surface of the gas diffusion layer are not particularly limited, and the same conditions as before can be applied by the specific forming method as described above.

  The gas diffusion layer preferably contains a water repellent in the base material for the purpose of further improving water repellency and preventing 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 a 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.

  When a water repellent is contained in the gas diffusion layer, 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.

  In addition, the manufacturing method of the joined body including the electrode catalyst layer, the solid polymer electrolyte membrane, and preferably the gas diffusion layer is not limited to the above-described method. That is, after applying and drying the catalyst ink on the solid polymer electrolyte membrane, hot pressing, the electrode catalyst layer is joined to the solid polymer electrolyte membrane, and the obtained joined body is sandwiched between the gas diffusion layers, MEA: a catalyst ink may be applied and dried on the gas diffusion layer to form an electrode catalyst layer, which may be joined to a solid polymer electrolyte membrane by hot pressing, or the like. What is necessary is just to use a technique suitably.

  Alternatively, the electrode catalyst layer according to the present invention is formed on a transfer mount using a lower alcohol as a solvent in the same manner as in the conventional method, and then infiltrated with a polar solvent having a relative dielectric constant of 20 to 50 at 20 ° C. Furthermore, the MEA may be manufactured by transferring the electrode catalyst layer to the electrolyte membrane. Alternatively, after the electrode catalyst layer according to the present invention is formed on the surface of the gas diffusion layer to produce an electrode catalyst layer-gas diffusion layer assembly, the dielectric constant at 20 ° C. is applied to the electrode catalyst layer-gas diffusion layer assembly. The MEA may be produced by infiltrating a polar solvent having a molecular weight of 25 or more and 50 or less and further joining it with an electrolyte membrane. Accordingly, in the third aspect of the present invention, after the electrode catalyst layer formed on the transfer mount is infiltrated with a polar solvent having a relative dielectric constant of 25 or more and 50 or less at 20 ° C., the electrode catalyst layer is solid polymerized. It is a manufacturing method of an electrolyte membrane electrode assembly which has a process of transferring to an electrolyte membrane. In the fourth aspect of the present invention, after an electrode catalyst layer is formed on the surface of the gas diffusion layer to produce an electrode catalyst layer-gas diffusion layer assembly, the electrode catalyst layer-gas diffusion layer assembly is subjected to 20 ° C. This is a method for producing an electrolyte membrane-electrode assembly, which comprises a step of infiltrating a polar solvent having a relative dielectric constant of 25 or more and 50 or less and then joining with a solid polymer electrolyte membrane. The above method uses an electrode catalyst layer made of a catalyst ink using a solvent such as a lower alcohol, as in the prior art, and before joining the catalyst layer thus prepared to the solid polymer electrolyte membrane, By infiltrating in the polar solvent according to the present invention in advance, the surface of the colloid existing in the electrode catalyst layer is dissolved in the polar solvent. In this way, the surface melts, and the molecular chains of the electrolyte polymer in the electrode catalyst layer are bonded (entangled) with the electrolyte polymer of the solid polymer electrolyte membrane. For this reason, the MEA formed in this manner has excellent adhesion, that is, the electrode catalyst layer and the solid polymer electrolyte membrane are firmly bonded. In addition, in this MEA, the molecular chains of the electrolyte polymer in a dissolved state on the colloidal surface are strongly bound (entangled) with the molecular chains of the electrolyte polymer, so that the mechanical strength of the catalyst layer is improved and the porous structure of the layer is not easily crushed. Therefore, the fuel cell using such MEA can maintain the porous structure of the catalyst layer even when used for a long period of time, and can effectively prevent / suppress the decrease in gas diffusivity. In addition, the output (power generation performance) does not decrease. Therefore, according to the method of the present invention, even a catalyst ink using a conventional alcohol solvent can produce an MEA having a sufficiently high performance.

  In the third and fourth aspects of the present invention, unless otherwise specified, the types of polar solvent, the electrode catalyst layer, the material of the solid polymer electrolyte membrane and the gas diffusion layer, the formation method and conditions, etc. The overlapping parts are the same as those described in the first and second aspects of the present invention, and will not be described here.

  In the third and fourth aspects of the present invention, the infiltration condition of the electrode catalyst layer / electrode catalyst layer-gas diffusion layer assembly into the polar solvent is such that the colloidal surface on the electrode catalyst layer is dissolved. Although it does not restrict | limit in particular, For example, after apply | coating the polar solvent by this invention to an electrode catalyst layer / electrode catalyst layer-gas diffusion layer assembly by spray etc., it is room temperature-100 degreeC in a vacuum dryer, More preferably, it is 50. A method of drying at -80 ° C for 30-60 minutes is preferably used. Further, the third and fourth aspects of the present invention differ only in whether or not they include a step of forming an electrode catalyst layer on the surface of the gas diffusion layer in the fourth aspect of the present invention. Same as three. In the third aspect of the present invention, as described above, the electrode catalyst layer formed on the transfer mount is infiltrated with a polar solvent having a relative dielectric constant of 25 to 50 at 20 ° C. After transferring the layer to the solid polymer electrolyte membrane, it is preferable to peel off the transfer mount and further provide a gas diffusion layer on the electrode catalyst layer side.

  The above-described MEA of the present invention uses a catalyst layer formed using a catalyst ink using a polar solvent as a cathode side and / or an anode side catalyst layer, thereby enabling long-term start / stop cycles and output fluctuation cycles. A sufficiently high power generation performance can be maintained as well as a decrease in power generation performance is suppressed. 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. However, the fuel cell is particularly useful for an automobile application in which system start / stop and output fluctuation frequently occur. It can be particularly preferably used.

  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. The separator can be used without limitation as long as it is conventionally known, such as those made of carbon such as dense carbon graphite and a carbon plate, and those made of metal such as stainless steel. The separator has a function of separating air and fuel gas, and a channel groove for securing the channel may be formed. The thickness and size of the separator, the shape of the flow channel, and the like are 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 the fuel cell can obtain a desired voltage or the like. The shape of the fuel cell is not particularly limited, and may be determined as appropriate so that desired battery characteristics such as voltage can be obtained.

  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: Method using DMSO as solvent for catalyst ink Preparation of Nafion in DMSO (5 wt%) Commercially available Nafion solution (dispersed / suspended Nafion at a concentration of 5 wt% in 1-propanol, manufactured by DuPont) in 100 g (ie, 5 g Nafion + 95 g 1-propanol), 95 g Add DMSO and stir and mix at room temperature for 10 minutes. Next, the mixed solution is heated on a rotary evaporator while being heated at 70 ° C. to evaporate 1-propanol in the mixed solution. When the weight of the mixed solution reaches 100 g, the heating is finished.

2. Preparation of catalyst ink Platinum-supported carbon fine particles (manufactured by Tanaka Kikinzoku Co., Ltd., trade name: TEC10E50E) and the above 1. The Nafion-DMSO solution prepared in step 1 is mixed and stirred at room temperature for 3 minutes to prepare a catalyst ink.

3. 1. Production of transfer sheet (decal) The catalyst ink prepared in the above is applied on a Teflon sheet (size: 5 cm × 5 cm) with a screen printer and dried in a vacuum dryer for 1 hour to produce a transfer sheet. At this time, the above process is repeated until the amount of platinum in the catalyst layer reaches 10 mg, and overcoating is performed.

4). The transfer Nafion film (size: 7 cm × 7 cm) of the electrode catalyst layer is used as described in 3. above. The two transfer sheets prepared in the above are sandwiched so that the catalyst layers are in contact with the Nafion film, and hot pressing is performed at 130 ° C. and 2 MPa for 10 minutes. After hot pressing, the Teflon sheet is peeled off to produce an MEA.

Example 2: Method of infiltrating a decal with DMSO Preparation of catalyst ink Predetermined amount of platinum-supported carbon fine particles (manufactured by Tanaka Kikinzoku Co., Ltd., trade name: TEC10E50E) and commercially available Nafion solution (dispersed / suspended Nafion at a concentration of 5 wt% in 1-propanol, DuPont) Are stirred and mixed at room temperature for 3 minutes.

2. Preparation of transfer sheet (decal) The catalyst ink prepared in the above is applied on a Teflon sheet (size: 5 cm × 5 cm) with a screen printer, and naturally dried for 1 hour to produce a transfer sheet. At this time, the above process is repeated until the amount of platinum in the catalyst layer reaches 10 mg, and overcoating is performed.

3. 1. Transfer of electrode catalyst layer DMSO is applied to the two transfer sheets prepared in the above by spraying or the like, and then heated to 80 ° C. in a vacuum dryer and dried for 1 hour. Next, a Nafion film (size: 7 cm × 7 cm) is sandwiched between the two transfer sheets so that the catalyst layer is in contact with the Nafion film, and hot pressing is performed at 130 ° C. and 2 MPa for 10 minutes. After hot pressing, the Teflon sheet is peeled off to produce an MEA.

Comparative Example 1
1. Preparation of catalyst ink Platinum-supported carbon fine particles (manufactured by Tanaka Kikinzoku Co., Ltd., trade name: TEC10E50E) and a commercially available Nafion solution (dispersed / suspended Nafion at a concentration of 5 wt% in 1-propanol, manufactured by DuPont) Mix and stir at room temperature for 3 minutes to prepare the catalyst ink.

2. Preparation of transfer sheet (decal) The catalyst ink prepared in the above is applied on a Teflon sheet (size: 5 cm × 5 cm) with a screen printer and dried in a vacuum dryer for 1 hour to produce a transfer sheet. At this time, the above process is repeated until the amount of platinum in the catalyst layer reaches 10 mg, and overcoating is performed.

3. The transfer Nafion film (size: 7 cm × 7 cm) of the electrode catalyst layer is applied to the above 2. The two transfer sheets prepared in the above are sandwiched so that the catalyst layers are in contact with the Nafion film, and hot pressing is performed at 130 ° C. and 2 MPa for 10 minutes. After hot pressing, the Teflon sheet is peeled off to produce an MEA.

Example 3
In order to verify the performance effect as a fuel cell, a cell start / stop cycle power generation test using the MEAs produced in Examples 1-2 and Comparative Example 1 was performed. The cell was obtained by sandwiching the MEA (electrolyte membrane-catalyst layer assembly) produced in Examples 1 and 2 and Comparative Example 1 with carbon paper (thickness 300 μm) serving as a gas diffusion layer from both sides. Used in the cell.

The experiment was conducted at a cell temperature of 70 ° C. During power generation, hydrogen gas (relative humidity 50%) was supplied to the anode and air (relative humidity 50%) was supplied to the cathode, and power generation was performed at a current density of 1 A / cm ² and stopped. At times, dry air was supplied as the purge gas for the anode. The cycle period was 2 minutes (power generation 1 minute, stop 1 minute), and 300 cycles were performed. The voltage value at a current density of 1 A / cm ² at the start and end of the experiment was measured, and the results are shown in Table 1 below.

  From the results shown in Table 1 above, when the MEAs of Examples 1 and 2 according to the present invention were used, the voltage at the end of the experiment exceeded that of Comparative Example 1, and the MEA using the catalyst ink of the present invention was used. It can be seen that the obtained cell can significantly suppress the output decrease due to the start / stop cycle and the output fluctuation cycle.

  Moreover, in order to confirm the change of the porous structure of the catalyst layer, SEM observation (30,000 times) of the cross section of the cathode side catalyst layer of the MEA used in the new and cycle tests was performed. As a result, the porous structures of the catalyst layers of Examples 1 and 2 were not significantly different from those of the new ones. However, in Comparative Example 1, crushing of pores was observed. The porosity of the catalyst layer estimated from the SEM image was 55% for new article, 53% for Example 1, and 50% for Example 2, whereas it was 35% for Comparative Example.

  The fuel cell having the MEA using the catalyst layer of the present invention because of the excellent mechanical strength of the catalyst layer of the present invention, the long-term start / stop cycle of the porous structure of the catalyst layer and the excellent ability to maintain the output fluctuation cycle, etc. Can be used particularly suitably in automotive applications where system start / stop and output fluctuations frequently occur.

A cross-sectional schematic diagram of a general polymer electrolyte fuel cell is shown.

Explanation of symbols

1. Solid polymer fuel cell,
2 ... Solid polymer electrolyte membrane,
3a ... anode side electrode catalyst layer,
3b ... cathode side electrode catalyst layer,
4a ... anode side gas diffusion layer,
4b ... cathode side gas diffusion layer,
5 ... MEA,
6a ... anode side separator,
6b ... cathode side separator,
7a, 7b ... gas supply grooves.

Claims (8)

  A catalyst ink for forming a fuel cell electrode comprising an electrode catalyst, an electrolyte and a solvent, wherein the solvent is a polar solvent having a relative dielectric constant at 20 ° C. of 25 to 50.   The polar solvent is selected from the group consisting of DMSO (dimethyl sulfoxide), DMAc (dimethylacetamide), NMP (N-methyl-2-pyrrolidinone), EG (ethylene glycol), DMF (N, N-dimethylformamide) and glycerin. The catalyst ink according to claim 1, wherein the catalyst ink is at least one kind.   An electrolyte membrane-electrode assembly having an electrode catalyst layer produced using the catalyst ink according to claim 1.   A step of infiltrating an electrode catalyst layer formed on a transfer mount with a polar solvent having a relative dielectric constant of 25 to 50 at 20 ° C., and then transferring the electrode catalyst layer to a solid polymer electrolyte membrane. And manufacturing method of electrolyte membrane-electrode assembly.   After the electrode catalyst layer is formed on the surface of the gas diffusion layer to produce an electrode catalyst layer-gas diffusion layer assembly, the electrode catalyst layer-gas diffusion layer assembly has a relative dielectric constant of 25 to 50 at 20 ° C. The manufacturing method of an electrolyte membrane electrode assembly which has the process of making it infiltrate the polar solvent which is and joining with a solid polymer electrolyte membrane.   The polar solvent is selected from the group consisting of DMSO (dimethyl sulfoxide), DMAc (dimethylacetamide), NMP (N-methyl-2-pyrrolidinone), EG (ethylene glycol), DMF (N, N-dimethylformamide) and glycerin. The method according to claim 4 or 5, which is at least one of the following.   A fuel cell comprising the electrolyte membrane-electrode assembly according to claim 3 or the electrolyte membrane-electrode assembly produced by the method according to any one of claims 4 to 6.   An automobile equipped with the fuel cell according to claim 7.

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