PTFE-Based Solid Polymer Electrolyte Membrane for High-Temperature Fuel Cell Applications

The demand for a solid polymer electrolyte membrane for fuel-cell systems, capable of withstanding temperatures above , has prompted this study. A low-cost, highly conductive, nanoporous proton-conducting membrane, based on a polytetrafluoroethylene (PTFE) backbone has been developed. It comprises a nonconductive nano-size ceramic powder, PTFE matrix, and an aqueous acid. Impregnation of the ceramic powder into the PTFE matrix was carried out using sol-gel synthesis. The preparation procedures were studied and the membrane was characterized. This membrane demonstrated promising properties of high thermal stability (up to ), pressure-retention difference up to , room-temperature conductivity up to (10–15% (w/w) , ), a hydrophilic/hydrophobic pore ratio of 1:1 and very high water flow at low pressure. A nonoptimized direct-methanol fuel cell with a thick membrane was assembled and tested. It produced at , (g) dry air, 1.9 stoich (air), and at , (g) dry air, 1.9 stoich (air).