Metal oxide-perfluorocarbon composite: A materials approach to elevated temperature PEM fuel cells

The proton exchange membrane (PEM) fuel cell presently operating at 60°-80°C is identified as the cell of choice for zero emission vehicle applications. However, these cells are limited by poor water management, and are subject to poisoning by the presence of trace amounts of CO in the fuel feed. One solution to these problems is the implementation of a PEM cell that operates at elevated temperatures (120°-150°C). Even though, the currently employed perfluoronated sulfonated ionomer membranes such as Nafion are thermally stable through this region, above 80°-90°C, these materials have difficulty retaining water. This degrades their proton transport properties. The use of a metal oxide composite membrane allows for reproducible, stable cell operation ≤ -145°C. Metal oxide/Nafion composite membranes can be prepared via the direct addition of metal oxide nano- or mesoscale particles to a Nafion recasting suspension. The performance of the composite membrane at 120°-150°C is a function of the specific chemical details of the metal oxide-polymer interface. Composite PEM cells show decreased sensitivity to CO exposure and water content. This is an abstract of a paper presented at the 229th ACS National Meeting (San Diego, CA 3/13-17/2005).