Solid Polymer Electrolyte and Process For Making Same

Abstract

A solid polymer electrolyte membrane having a first surface and a second surface opposite the first surface, where the solid polymer electrolyte membrane has a failure force greater than about 115 grams and comprises a composite membrane consisting essentially of (a) at least one expanded PTFE membrane having a porous microstructure of polymeric fibrils, and (b) at least one ion exchange material impregnated throughout the porous microstructure of the expanded PTFE membrane so as to render an interior volume of the expanded PTFE membrane substantially occlusive; (c) at least one substantially occlusive, electronically insulating first composite layer interposed between the expanded PTFE membrane and the first surface, the first composite layer comprising a plurality of first carbon particles supporting a catalyst comprising platinum and an ion exchange material, wherein a plurality of the first carbon particles has a particle size less than about 75 nm, or less than about 50 nm, or less than about 25 nm.

We claim: 
     
         1 . A method of making a solid polymer electrolyte membrane comprising the steps of (a) preparing an ink solution comprising a precious metal catalyst on a supporting particle and an ion exchange material; (b) providing a polymeric support having a microstructure of micropores; (c) impregnating said microstructure with said ink solution to form a substantially air occlusive composite membrane.