Enhancement of the fuel cell performance of a high temperature proton exchange membrane fuel cell running with titanium composite polybenzimidazole-based membranes

The fuel cell performance of a composite PBI-based membrane with TiO2 has been studied. The behaviour of the membrane has been evaluated by comparison with the fuel cell performance of other PBI-based membranes, all of which were cast from the same polymer with the same molecular weight. The RI composite membrane incorporating TiO2 showed the best performance and reached 1000 mW cm(-2) at 175 degrees C. Moreover, this new titanium composite PBI-based membrane also showed the best stability during the preliminary long-term test under our operation conditions. Thus, the slope of the increase in the ohmic resistance of the composite membrane was 0.041 m Omega cm(2) h(-1) and this is five times lower than that of the standard PBI membrane. The increased stability was due to the high phosphoric acid retention capacity - as confirmed during leaching tests, in which the Ti-based composite PBI membrane retained 5 mol of H3PO4/PBI r.u. whereas the PBI standard membrane only retained 1 mol H3PO4/PBI r.u. Taking into account the results obtained in this study, the TiO2-PBI based membranes are good candidates as electrolytes for high temperature PEMFCs. (C) 2011 Elsevier B.V. All rights reserved.