Patent ID: 7232624

Claim:
A method of producing a membrane and electrode assembly (MEA) comprising: (a) mixing a metal catalyst with pure water, perfluorinated polymer ionomer and a polar organic solvent to prepare a catalyst layer forming composition; (b) coating the catalyst layer forming composition onto a diffusion layer formed on an electrode support, drying to form a catalyst layer, thereby preparing a cathode and an anode, respectively; (c) interposing an electrolyte membrane between the anode and the cathode; and (d) sealing the electrolyte membrane between the anode and the cathode, wherein the catalyst layer forming composition in step (a) is prepared by mixing the metal catalyst with pure water and then mixing the polymer ionomer and the polar organic solvent thereto, wherein the content of the pure water is in the range of 140 to 160 parts by weight based on 100 parts by weight of the metal catalyst, and wherein the diffusion layer is formed by: mixing a fluorine resin and an organic solvent to form a diffusion layer forming composition; applying the diffusion layer forming composition to a cathode support and an anode support; drying the diffusion layer forming composition; and sintering the diffusion layer forming composition to form a cathode diffusion layer and an anode diffusion layer, respectively.