Abstract: Fuel cells will undoubtedly find widespread use in this new millennium in the conversion of chemical to electrical energy, as they offer very high efficiencies and have unique scalability in electricity generation applications. The solid oxide fuel cell (SOFC) offers certain advantages over lower temperature fuel cells, notably its ability to utilise CO as a fuel rather than being poisoned and the availability of high-grade exhaust heat for combined heat and power or combined cycle gas turbine applications. Although cost is clearly a key barrier to widespread SOFC implementation, perhaps the most important technical barriers currently being addressed relate to the electrodes, particularly the fuel electrode or anode. In terms of mitigating global warming, the ability of the SOFC to utilise commonly available fuels at high efficiency, promises an effective and early reduction in carbon dioxide emissions and hence is one of the lead new technologies to improve the environment. In the longer term the ability to utilise waste derived fuels such as biogas will be of critical importance.
Here we describe a series of strategies involving modification of defect chemistry and composition to enhance the electrocatalytic performance of novel perovskite anode and cathode materials that have proved highly successful in reducing polarization resistance and improving output voltage. Results will be presented addressing the use of natural gas, liquid hydrocarbon and carbon-based fuels. Strategies to improve sulphur tolerance, coking resistance and redox stability will be described and the long term prospects discussed. We also report on the microstructural evolution of Mn-containing perovskites impregnated into yttria stabilised zirconia scaffolds on heating and redox cycling This seems to offer a very attractive structure with extensive triple phase boundary regions being formed where electrochemical reactions can occur