Published online by Cambridge University Press: 15 February 2011
Chemical and physical requirements limit the choice of fuel cell electrolytes to strong aqueous acids and alkalis, (pyro)phosphoric acid, carbonate melts, and solid oxides (O= conductors, with rare H+ conductors). The choice of electrolytes and operating temperatures is therefore limited, controlling the choice of other materials (anode catalysts, cathode catalysts, current collectors, and construction materials), which are determined by the properties of the electrolyte, the temperature, the electrode potentials, the gas atmospheres, and thermodynamic and kinetic considerations. The families of state-of-the art and new materials for each class of electrolyte are reviewed. The area of greatest activity is the solid oxide fuel cell (500°C-1000°C). In a review of this length, the extensive list of new solid oxide developments can only be given by way of introduction.