JP2011077006A - Manufacturing method of electrode catalyst layer for solid polymer fuel cell, electrode catalyst layer for solid polymer electrolyte fuel cell, manufacturing method of membrane-electrode assembly, and membrane-electrode assembly - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of an electrode catalyst layer for a solid polymer fuel cell and the electrode catalyst layer for the solid polymer fuel cell, wherein when obtaining the solid polymer fuel cell, all of a gas channel, a proton conductive path, and a three-phase interface can be increased by using freeze-drying method. <P>SOLUTION: The method is carried out through a process which includes: (1) a step of coating a dispersion liquid containing proton conductive polymer on a base material surface, freezing it before a solvent is dried, and drying is carried out in a vacuum; (2) a step of impregnating and drying a dispersion liquid of catalyst-carrying carbon into a porous membrane of the proton conductive polymer obtained in the step (1); and (3) a step of impregnating and drying the dispersion liquid of the proton conductive polymer in an intermediate into which the catalyst-carrying carbon is impregnated in pores of the porous membrane of the proton conductive polymer obtained in the step (2). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for producing an electrode catalyst layer for a polymer electrolyte fuel cell, an electrode catalyst layer for a polymer electrolyte fuel cell, and a polymer electrolyte fuel cell using the same.

  A fuel cell is a power generation system that generates electricity by using hydrogen and oxygen as fuel and causing reverse reaction of water electrolysis. This has features such as high efficiency, low environmental load and low noise compared with the conventional power generation method, and is attracting attention as a clean energy source in the future. In particular, polymer electrolyte fuel cells that can be used near room temperature are considered promising for use in in-vehicle power sources and household stationary power sources, and various research and development have been conducted in recent years.

  Issues for the practical application of fuel cells include power density, gas utilization, improved durability, and cost reduction. In order to improve the power density and the gas utilization rate, it is necessary to supply fuel gas and proton sufficiently and to increase the surface area of the oxidation-reduction reaction site in the catalyst electrode. The most demanded for cost reduction is a reduction in the amount of platinum used as a catalyst for the electrode.

A polymer electrolyte fuel cell is generally configured by laminating a large number of single cells. A single cell has a structure in which a membrane / electrode assembly formed by sandwiching a solid polymer electrolyte membrane between two electrodes, an oxidation electrode and a reduction electrode, is sandwiched by a separator having a gas flow path. Oxidation of hydrogen gas occurs at the oxidation electrode, and reduction of hydrogen ions occurs at the reduction electrode. This oxidation-reduction reaction occurs inside the electrode only on the surface of the catalyst that is in contact with both the carbon particles that are the electron conductor and the proton conductor and that can adsorb the introduced gas. This part where the redox reaction takes place is called the three-phase interface. The large area of the three-phase interface and satisfying the proton and fuel gas supply path to the three-phase interface lead to an improvement in the output density and gas utilization rate of the single cell.
For this purpose, it is necessary to improve the diffusibility of the gas in the catalyst layer, the drainage of the generated water, the water content of the proton conductive polymer, the proton conductivity, and the like. In addition, platinum catalyst particles that are not located at the three-phase interface do not contribute to the oxidation-reduction reaction of the electrode, and thus do not function at all. In order to reduce the amount of platinum used, it is necessary to reduce the amount of platinum that does not function as much as possible and increase the effective utilization rate of the platinum used.

  Conventionally, the catalyst layer is often formed on a base material by various coating methods, screen printing methods, or the like, by mixing a catalyst-supporting carbon, a proton conductive polymer, and a solvent. In this case, agglomeration of the catalyst-supported carbon is likely to occur when the coated catalyst ink is dried. As a result, the interface between the catalyst and the proton-conductive polymer is reduced, or the porosity in the catalyst layer is reduced to reduce the fuel. There was a tendency for the power density of the cell to decrease due to the gas path being cut off.

  Thus, attempts have been made to use freeze-drying in order to prevent aggregation of the catalyst-supporting carbon and increase the three-phase interface (see, for example, Patent Documents 1 and 2). Freeze-drying is performed by freezing water-containing material and sublimating the ice under vacuum. The material after freeze-drying can maintain its shape when frozen, and is conventionally stored in the food industry. It is a drying method used in the food manufacturing and medical / pharmaceutical fields. Patent Document 1 discloses that a catalyst layer-constituting powder is obtained by freeze-drying an ink in which catalyst-supported carbon, proton conductive polymer, and a solvent are mixed, followed by heat treatment and pulverizing, and obtaining the catalyst layer by forming the powder into a sheet. Is. However, in the method according to Patent Document 1, the formation of a proton conduction path by the proton conducting polymer is insufficient even when the reaction point is increased, and the resistance of the catalyst layer increases due to the decrease in proton conductivity. There are concerns that it will not grow that much. In Patent Document 2, a catalyst layer is obtained by adding a solvent to a freeze-dried ink obtained by mixing catalyst-carrying carbon, a proton conductive polymer, and a solvent, and applying the ink again. In the method according to Patent Literature 2, the adsorption of the proton-conductive polymer is peeled off due to dispersion mixing during reinking, and the catalyst-carrying carbon is agglomerated or the pores serving as gas channels are crushed. Not much improvement.

JP-A-8-185865 JP 2003-86190 A

  The present invention has been made to solve the above problems, and in obtaining a polymer electrolyte fuel cell, the gas channel, the proton conduction path, and the three-phase interface are all increased using a freeze-drying method. It is an object of the present invention to provide a method for producing an electrode catalyst layer for a polymer electrolyte fuel cell and an electrode catalyst layer for a polymer electrolyte fuel cell.

  As means for solving the above-mentioned problems, the invention according to claim 1 is: (1) A dispersion containing a proton-conductive polymer is applied to the surface of a substrate and frozen before the solvent is dried. A step of drying, (2) a step of impregnating the porous membrane of the proton conductive polymer obtained in the step (1) with a dispersion of the catalyst-supporting carbon and drying, and (3) obtained in the step (2). A solid polymer type comprising a step of impregnating a catalyst-supported carbon in the pores of a porous membrane of a proton conductive polymer impregnated with a catalyst-supported carbon and impregnating the intermediate with a dispersion of the proton conductive polymer It is a manufacturing method of the electrode catalyst layer for fuel cells.

  The invention according to claim 2 is a method for producing a membrane electrode assembly comprising a polymer electrolyte membrane and a pair of electrode catalyst layers sandwiching the polymer electrolyte membrane, and the method according to claim 1. A membrane characterized in that an electrode catalyst layer obtained by a production method is disposed at least on the cathode side of the polymer electrolyte membrane, and is brought into close contact with the polymer electrolyte membrane by applying pressure at a temperature that is a glass transition point of the polymer electrolyte membrane. It is a manufacturing method of an electrode assembly.

  The invention according to claim 3 is a membrane electrode assembly obtained by the manufacturing method according to claim 2.

  The invention according to claim 4 is an electrode catalyst layer for a polymer electrolyte fuel cell containing catalyst-supporting carbon and a proton conducting polymer, and a dispersion containing the proton conducting polymer is applied to the surface of the substrate. An electrode catalyst layer for a solid polymer fuel cell, wherein the proton-conductive polymer is a continuous porous body by passing through a step of freezing before drying the solvent and drying under vacuum .

  According to the invention of claim 1, a porous body made of a proton conductive polymer can be obtained, and impregnated with a dispersion of catalyst-carrying carbon and proton conductive polymer to thereby obtain a proton conductive polymer. The catalyst-supported carbon coated with the proton conducting polymer is adsorbed on the surface of the porous material, and the electrode catalyst layer for the polymer electrolyte fuel cell is manufactured with the gas channel, proton conducting path, and three-phase interface all increased. We were able to.

  According to the second aspect of the present invention, the gas channel, proton conduction path, and three-phase interface are all increased, and a membrane electrode assembly with improved power generation performance can be manufactured.

  According to the third aspect of the invention, the power generation performance of the fuel cell can be improved by using the electrode catalyst layer in which all of the gas channel, proton conduction path, and three-phase interface are increased.

  According to the invention of claim 4, a porous body made of a proton conductive polymer can be obtained, and by using this for the electrode catalyst layer, the gas channel and the proton conduction path can be increased.

It is a schematic cross section of a mode change in each process of an electrode catalyst layer by a manufacturing method of the present invention. It is a schematic diagram of the three-phase interface of the electrode catalyst layer of this invention. It is a schematic cross section of the membrane electrode assembly using the electrode catalyst layer of the present invention.

  Hereinafter, embodiments of the present invention will be described in detail. Note that this embodiment is an example of the present invention and does not limit the present invention. lang = EN-US> In the present invention, when obtaining an electrode catalyst layer for a solid polymer fuel cell containing a catalyst-supporting carbon and a proton conducting polymer, a dispersion containing the proton conducting polymer is applied to the substrate surface. Before the solvent is dried, it is frozen and dried under vacuum to obtain a proton conductive polymer porous material. The proton conductive polymer porous material is impregnated with a catalyst-supported carbon dispersion and dried. Efficient formation of gas channels, proton paths, and three-phase interfaces is achieved by obtaining an intermediate with catalyst-supported carbon adhering to the surface of the pores, and further impregnating the intermediate with a dispersion of proton-conducting polymer and drying. To do.

As a catalyst used in the present invention, a platinum group element such as platinum, palladium, ruthenium, iridium, rhodium, osmium, a metal such as iron, lead, copper, chromium, cobalt, nickel, manganese, vanadium, molybdenum, gallium, aluminum or the like These alloys, oxides, double oxides, carbides, etc. can be used.
Moreover, when the particle size of these catalysts is too large, the specific surface area per mass of the catalyst decreases, and as a result, the current value obtained per unit mass of the catalyst becomes small. Conversely, when too small, since stability of a catalyst falls, 0.5-50 nm is preferable, More preferably, it is 1-5 nm.

The carbon supporting these catalysts used in the present invention may be any carbon as long as it is finely powdered and has conductivity and is not affected by the catalyst. Carbon black, graphite, graphite, activated carbon, carbon Nanotubes and fullerenes can be preferably used.
If the particle size of the carbon is too small, it becomes difficult to form an electron conduction path, and if it is too large, the gas diffusibility of the catalyst layer is reduced or the utilization factor of the catalyst is lowered. More preferably, 10-100 nm is good.

  Various proton conductive polymers are used, but considering the interface resistance between the polymer electrolyte membrane and the electrode, and the dimensional change rate between the electrode and the electrolyte membrane when the humidity changes, the electrolyte membrane and catalyst to be used The proton conducting polymer in the layer should be the same component.

  The proton conductive polymer used in the membrane electrode assembly of the present invention is not limited as long as it has proton conductivity, and a fluorine-based polymer electrolyte and a hydrocarbon-based polymer electrolyte can be used. Examples of the fluoropolymer electrolyte 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 Gore Select (registered trademark) manufactured by Gore. Etc. can be used. As the hydrocarbon polymer electrolyte, sulfonated polyetherketone, sulfonated polyethersulfone, sulfonated polyetherethersulfone, sulfonated polysulfide, sulfonated polyphenylene and the like can be used. Among these, a Nafion (registered trademark) material manufactured by DuPont can be suitably used as the polymer electrolyte membrane. As the hydrocarbon polymer electrolyte membrane, electrolyte membranes such as sulfonated polyetherketone, sulfonated polyethersulfone, sulfonated polyetherethersulfone, sulfonated polysulfide, and sulfonated polyphenylene can be used.

The solvent used as the dispersion medium in the present invention is not particularly limited as long as it does not erode the catalyst particles and the proton conductive polymer and can dissolve or disperse the proton conductive polymer in a highly fluid state as a fine gel. There is no limit. The solvent may contain water that is compatible with the proton conductive polymer. The amount of water added is not particularly limited as long as the proton conductive polymer is not separated to cause white turbidity or gelation.
The solvent for dispersing the catalyst-supporting carbon in the step (2) and the solvent for dispersing the proton conductive polymer in the step (3) preferably include at least a volatile liquid organic solvent. Those used have a high risk of ignition, and when such a solvent is used, it is preferable to use a mixed solvent with water.

The volatile liquid organic solvent is not particularly limited. Specifically, for example, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutyl alcohol, tert-butyl alcohol, Alcohols such as pentanol, acetone, methyl ethyl ketone, pentanone, methyl isobutyl ketone, heptanone, cyclohexanone, methyl cyclohexanone, acetonyl acetone, diisobutyl ketone and other ketone solvents, tetrahydrofuran, dioxane, diethylene glycol dimethyl ether, anisole, methoxytoluene, di Ether solvents such as butyl ether, other dimethylformamide, dimethylacetamide, N-methylpyrrolidone, ethylene glycol, diethylene glycol Lumpur, diacetone alcohol, 1 such as a polar solvent such as methoxy-2-propanol can be exemplified.
Although these can also be used independently, what mixed 2 or more types of these solvents can also be used.

  Distributed processing can be performed using various apparatuses. Examples thereof include a ball mill, a roll mill, a shear mill, a wet mill, and an ultrasonic dispersion treatment. Moreover, you may use the homogenizer etc. which stir with centrifugal force.

  FIG. 1 is a schematic cross-sectional view of a state change for each step of an electrode catalyst layer according to the production method of the present invention. The proton-conductive polymer porous body 10 is obtained by applying a dispersion containing a proton-conductive polymer to the surface of the substrate 12 and freezing and vacuum-drying the solvent before the solvent is dried.

  FIG. 1A shows a state in which a dispersion containing a proton conductive polymer is applied to the surface of the substrate 12 and frozen before the solvent is dried. The frozen solvent 11 actually exists three-dimensionally continuously in a state where the proton conductive polymer is dispersed.

  FIG. 1 (b) shows a state dried further under vacuum from the state shown in FIG. 1 (a), and the solvent sublimated from the portion where the frozen solvent 11 was present to become pores 13.

  FIG. 1 (c) shows a state where the proton conductive polymer porous body 10 has been subjected to a step of impregnating and drying a catalyst-supporting carbon dispersion and a step of impregnating and drying the proton conductive polymer dispersion. By these steps, the catalyst-supporting carbon and the proton conductive polymer are adsorbed on the surface of the proton conductive polymer porous body 10, and the electrode catalyst layer 1 in which the portion 14 having a three-phase interface is formed is obtained. Actually, since the proton conductive polymer porous body 10 and the pores 13 exist three-dimensionally continuously, the portion 14 having a three-phase interface also exists three-dimensionally in the same manner. .

  FIG. 2 is a schematic view of the three-phase interface of the electrode catalyst layer of the present invention, and shows in detail the portion 14 having the three-phase interface shown in FIG. Since the solvent in which the catalyst-carrying carbon is dispersed in the step (2) appropriately dissolves the surface of the proton conductive polymer porous body, the carbon particles 16 carrying the catalyst particles 15 are bonded to the proton conductive polymer porous body 10. Part is buried and fixed. Further, by embedding it with the proton conductive polymer 17 in the step (3), a three-phase interface and a proton path are formed.

  FIG. 3 is a schematic cross-sectional view of a membrane electrode assembly using the electrode catalyst layer of the present invention. The electrode catalyst layer 1 formed on the surface of the substrate 12 is placed on the polymer electrolyte membrane 18 and hot pressed to bring the electrode catalyst layer 1 into close contact with the polymer electrolyte membrane 18. After the adhesion, the substrate 12 is peeled from the electrode catalyst layer 1 to obtain a membrane electrode assembly 19.

  The electrode catalyst layer of the present invention can be disposed on both the anode side and the cathode side of the polymer electrolyte membrane, but is more preferably disposed on the cathode side. By disposing on the cathode side, the power generation efficiency can be improved, and furthermore, a voltage drop due to clogging of generated water and blocking of the pores can be suppressed.

  The substrate 12 used in the present invention includes, for example, an ethylene tetrafluoroethylene copolymer (ETFE), a tetrafluoroethylene-hexafluoropropylene copolymer (FEP), a tetrafluoroperfluoroalkyl vinyl ether copolymer (PFA), A fluororesin excellent in transferability such as polytetrafluoroethylene (PTFE) can be used. Polymer films such as polyimide, polyethylene terephthalate, polyamide (nylon), polysulfone, polyethersulfone, polyphenylene sulfide, polyether ether ketone, polyetherimide, polyarylate, and polyethylene naphthalate can also be used.

  When the substrate 12 is a gas diffusion electrode, it is not necessary to peel off the gas diffusion layer that is the substrate after hot pressing. As a gas diffusion layer, what is used for the normal fuel cell can be used. Specifically, porous carbon materials such as carbon cloth, carbon paper, and non-woven fabric can be used as the gas diffusion layer. A sealing layer may be formed between the gas diffusion layer and the electrode catalyst layer. The sealing layer is a layer that prevents the catalyst ink from permeating into the gas diffusion layer, and deposits on the sealing layer to form a three-phase interface even when the coating amount is small. Such a sealing layer can be formed, for example, by kneading carbon particles and a fluorine resin and sintering them at a temperature equal to or higher than the melting point of the fluorine resin. As the fluororesin, polytetrafluoroethylene (PTFE) or the like can be used.

  The pressure applied to the electrode catalyst layer in the hot pressing step affects the battery performance of the membrane electrode assembly. In order to obtain a membrane electrode assembly with good battery performance, the pressure A applied to the base material 12 and the proton conductive porous polymer body 10 is preferably 0.5 MPa ≦ A ≦ 20 MPa, more preferably 2 MPa ≦ A ≦ 15 MPa. When the pressure is higher than this, the electrode catalyst layer is excessively compressed, and when the pressure is lower than this, the bondability between the electrode catalyst layer and the polymer electrolyte membrane is lowered, and the battery performance is lowered.

  The generation of wrinkles in the membrane / electrode assembly is affected by the pressure B applied to the portion of the polymer electrolyte membrane in the hot pressing process. When B is small and the difference from A is large, wrinkles are likely to occur in the polymer electrolyte membrane. B can be defined by the ratio A / B of A to B, and preferably 1 <A / B ≦ 3. More preferably, 1 <A / B ≦ 2.

  The above pressure condition can be reproduced by using a buffer material having an appropriate compression rate. The cushioning material may be of a size that covers all of the laminate to be hot pressed. Moreover, what is compressed in the direction parallel to a pressurization direction when pressurized in the thickness direction is good.

  The hot pressing temperature is set near the glass transition point of the proton conducting polymer of the polymer electrolyte membrane and the electrode catalyst layer, which improves the bondability at the interface between the polymer electrolyte membrane and the electrode catalyst layer and reduces the interface resistance. It is effective in terms of suppression, and is desirably 100 ° C. or higher.

(Example)
<Preparation of transfer sheet>
A commercially available proton conductive polymer (Nafion: registered trademark of DuPont) solution was applied to an ETFE sheet and immersed in liquid nitrogen and frozen before the solvent dried. Before this was melted, it was dried with a freeze dryer (FD-81-TA manufactured by Tokyo Rika Kikai Co., Ltd.) to obtain a proton conductive polymer porous sheet. On the other hand, a platinum-supported carbon catalyst (trade name: TEC10E50E, manufactured by Tanaka Kikinzoku Kogyo Co., Ltd.), a mixed solvent of water and ethanol was mixed, and dispersion treatment was performed using a planetary ball mill to prepare a carbon-supported dispersion liquid. The proton conductive polymer porous sheet was immersed in a carbon dispersion while supporting the catalyst, and then the solvent was removed by drying under reduced pressure to obtain an intermediate. Subsequently, this intermediate was immersed in a solution of a commercially available proton conductive polymer (Nafion: registered trademark of DuPont) and dried in an oven at 80 ° C. to obtain an electrode catalyst layer transfer sheet.
<hot press>
The transfer sheet of the electrode catalyst layer is punched into a square, and the transfer sheet is arranged so as to face both surfaces of the polymer electrolyte membrane (Nafion 212: registered trademark, manufactured by Dupont) to form a laminated body, 120 ° C., 60 kgf / cm ² , Hot pressing was performed under conditions of 30 minutes, and bonding and lamination were performed to obtain a membrane electrode assembly shown in FIG.
<Evaluation 1>
The power generation performance of the produced membrane electrode assembly was measured.
Membrane / electrode joint made of a pair of separators made of a conductive and gas-impermeable material with a gas flow channel for reaction gas flow and a cooling water flow channel for cooling water flow on the opposite main surface A measurement cell that sandwiched the body and clamped both poles with bolts was used.
The evaluation conditions were a cell temperature of 80 ° C., the reaction gas was hydrogen at the oxidation electrode, and air at the reduction electrode. The relative humidity of the reaction gas was 30% and 100%. The performance was evaluated by the current density when the voltage was 0.7V and 0.3V.
<Evaluation 2>
Cyclic voltammetry measurement was performed using the measurement cell used in Evaluation 1.
The evaluation conditions were a cell temperature of 80 ° C., hydrogen gas was passed through the oxidation electrode, and nitrogen gas was passed through the reduction electrode, and the relative humidity of the reaction gas was 30% and 100%. The performance was evaluated by the peak charge amount Q value of hydrogen oxidative desorption.

(Comparative example)
<Preparation of transfer sheet>
A platinum-supported carbon catalyst (trade name: TEC10E50E, manufactured by Tanaka Kikinzoku Kogyo Co., Ltd.) and a 20% by mass polymer electrolyte solution (Nafion: registered trademark, manufactured by Dupont) are mixed with a mixed solvent of water and ethanol, and a planetary ball mill is used. Dispersion treatment was performed to prepare a catalyst ink. A catalyst ink was applied using an ETFE sheet as a base material and dried in an oven at 80 ° C. to prepare a transfer sheet.
<hot press>
A membrane electrode assembly was obtained in the same manner as in Example.
<Evaluation 1>
The power generation performance was measured and the performance was evaluated and compared in the same manner as in the examples.
<Evaluation 2>
The power generation performance was measured and the performance was evaluated and compared in the same manner as in the examples.

  In the examples, the proton conducting path is well formed by using the proton conducting polymer porous material obtained by lyophilization, so that a high current density can be obtained even when the relative humidity is low, The performance was excellent. In addition, the use of a proton-conductive polymer porous material obtained by freeze-drying provides a good channel for gas channels and produced water, so that even when relative humidity is high, power generation performance is reduced due to water clogging. Has not occurred. Further, in the examples, the Q value is high, suggesting that the three-phase interface is well formed.

  In the electrode catalyst layer of the present invention, the gas channel, the proton conduction path, and the three-phase interface are all formed with high efficiency, and the solid polymer fuel cell using the electrode catalyst layer of the present invention has good power generation performance. Therefore, the present invention can be suitably used for a fuel cell using a polymer electrolyte membrane, particularly a stationary cogeneration system and an electric vehicle. In addition, the area of the three-phase interface is increased, and the diffusibility of protons and fuel gas to the three-phase interface and the drainage of the generated water are improved, leading to an improvement in gas utilization. This improves the effective utilization rate of platinum. In other words, since the amount of platinum used can be reduced and the cost can be reduced, the industrial utility value is great.

DESCRIPTION OF SYMBOLS 1 ... Electrode catalyst layer 10 ... Proton conductive polymer porous body 11 ... Frozen solvent 12 ... Base material 13 ... Pore 14 ... Part 15 which has a three-phase interface ... Catalyst particle 16 ... Carbon particle 17 ... Proton conductive polymer 18 ... Polymer electrolyte membrane 19 ... Membrane electrode assembly

Claims (4)

(1) A step of applying a dispersion containing a proton-conducting polymer to the surface of a substrate and freezing the solvent before drying to dry under vacuum;
(2) a step of impregnating the proton-conductive polymer porous film obtained in the step (1) with a catalyst-supported carbon dispersion and drying;
(3) a step of impregnating a catalyst-supporting carbon impregnated with pores of the porous membrane of the proton conductive polymer obtained in the step (2) with a dispersion of the proton conductive polymer and drying the intermediate. A method for producing an electrode catalyst layer for a polymer electrolyte fuel cell, comprising: A method for producing a membrane / electrode assembly comprising a polymer electrolyte membrane and a pair of electrode catalyst layers sandwiching the polymer electrolyte membrane,
The electrode catalyst layer obtained by the production method according to claim 1 is disposed at least on the cathode side of the polymer electrolyte membrane, and is brought into close contact by pressurizing at a temperature that is a glass transition point of the polymer electrolyte membrane. A method for producing a membrane electrode assembly, comprising:   A membrane electrode assembly obtained by the production method according to claim 2. An electrode catalyst layer for a polymer electrolyte fuel cell containing a catalyst-supporting carbon and a proton conducting polymer,
Proton-conducting polymer is a continuous porous material by applying a dispersion containing proton-conducting polymer to the surface of the substrate and freezing the solvent before drying, followed by drying under vacuum. An electrode catalyst layer for a polymer electrolyte fuel cell.

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