A METHANOL IMPERMEABLE PROTON CONDUCTING COMPOSITE ELECTROLYTE SYSTEM

The concept of a proton conducting, methanol impermeable composite ele ctrolyte system is demonstrated. A three-layered laminar electrolyte c onsisting of a dense, methanol impermeable protonic conductor sandwich ed between proton permeable electronically insulating layers permits t he selective transport of protons while eliminating methanol crossover to the cathode. We demonstrate the selectivity of the composite elect rolyte using palladium foil sandwiched between two Nafion(TM) polymer membranes. The open-circuit voltage for an H-2/O-2 fuel cell utilizing this composite electrolyte is unaffected by introduction of methanol to the H, fuel stream, whereas conventional polymer electrolyte cells suffer severe degradation of performance due to methanol crossover.