Membrane electrode unit for polymer electrolyte fuel cells and method of producing the same

摘要

Membrane-electrode unit consists of a polymer electrolyte membrane having a first side and a second side both having porous reaction layers and gas distributor layers. The reaction layers contains precious metal catalysts supported on carbon, and ionomers. One of the reaction layers additionally contains a precious metal. An Independent claim is also included for the production of a membrane-electrode unit comprising: (a) applying a reaction layer containing a precious metal on the first side of the polymer electrolyte membrane; (b) applying the second reaction layer on the second side of the polymer electrolyte membrane; and (c) contacting the reaction layers with the gas distribution layers. The step of applying the reaction layer on the first side of the membrane comprises preparing an ink by mixing the precious metal and the supported catalyst in a solution of an ion-conducting polymer in a solvent, dispersing and homogenizing the ink, coating the first side of the membrane with the ink, and finishing the reaction layer by drying the coating. Preferably the total thickness of one reaction layer is 5-100, preferably 10-50 microns.