Fuel Cells - Proton-Exchange Membrane Fuel Cells | Membranes: Elevated Temperature

The many positive attributes of the proton-exchange membrane fuel cell (PEMFC) are overshadowed by their susceptibility to carbon monoxide poisoning, need for highly regulated thermal control, and detailed water management. These issues can be diminished through the development of elevated-temperature PEMFCs. The key materials issue facing cell operation at elevated temperatures is the development of membrane electrolytes that function in the 120-150 °C temperature range. Recently, several membrane systems have been developed that overcome the normal temperature limitations of standard pure sulfonated perfluorocarbon membranes (60-80 °C) and in certain cases allow cell operation up to temperatures approaching 200 °C. These membranes also show superior performance at diminished relative humidity levels. Three classes of systems having demonstrated elevated temperature proton exchange membrane (PEM) properties are considered here: Nafion®/inorganic composites, polybenzimidazole /ionomer systems, and solid-acid membranes. The composition, mechanism of operation, and output parameters for cells containing recently identified elevated-temperature PEM materials are reviewed here.