Approaches and technical challenges to high temperature operation of proton exchange membrane fuel cells

Water loss and the coincident increase in membrane resistance to proton con duction are significant barriers to high performance operation of tradition al proton exchange membrane fuel cells at elevated temperatures where the r elative humidity may be reduced. We report here approaches to the developme nt of high temperature membranes for proton exchange membrane fuel cells; c omposite perfluorinated sulfonic acid membranes were prepared to improve wa ter retention, and non-aqueous proton conducting membranes were prepared to circumvent the loss of water. Experimental results of composite membranes of Nafion and zirconium phosphate show improved operation at elevated tempe ratures. Imidazole impregnated membranes poisoned the electrocatalysts. Ces ium hydrogen sulfate membranes were not able to produce appreciable current . A brief analysis of temperature requirements for CO tolerance and a frame work for understanding water loss from fuel cell membranes are presented. ( C) 2001 Elsevier Science B.V. All rights reserved.