A Sol-Gel Derived Organic/Inorganic Hybrid Membrane for Intermediate Temperature PEFC

Intermediate temperature operation of polymer electrolyte fuel cells has been pointed out to be a promising option to overcome most of the technological problems of the current PEM system and new classes of electrolyte membrane have been investigated elsewhere. Proton conducting organic/inorganic nano-hybrid polymer electrolyte membranes have been synthesized in the present work. The membranes were synthesized by bridging temperature tolerant polyether polymers such as PEO or PTMO to inorganic silicate moieties to form organic/inorganic hybrid macromolecules. The hybrid membranes become proton conducting polymer electrolytes by doping with heteropolyacids such as 12-phosphotungstic acid (PWA). The conducting properties of the membrane were studied by modifying the polyether structure, molecular weight, PWA concentration, water content, and also various processing conditions. The membranes are flexible and thermally stable due to the temperature tolerant inorganic frameworks of the macromolecules. The proton conductivity of the membranes is in a range from 10(-3)-10(-2) S/cm up to 140 degrees C under controlled humidity.