Al-Doped (La,Sr)TiO(3+delta) Anodes for the Direct Oxidation of Methane in SOFCs

Perovskite (La,Sr)TiO(3+delta) compounds have been identified as suitable materials for solid oxide fuel cell (SOFC) anodes, due to their high conductivity and stability in reducing conditions. Additionally, when using hydrocarbon fuels, these materials have been proven resistant to carbon deposition. Previous research has shown that the fuel cell performance can be significantly improved by replacing the titanium on the perovskite B-site with other elements. (La,Sr)TiO(3+delta) compounds, doped with aluminium, were synthesised by solid state reaction. Structural analysis, by XRD and TEM, revealed the structure of these compounds varies with the aluminium content and the amount of oxygen excess (delta). The electrical properties of these materials were analysed using A.C. impedance and four point D.C. conductivity measurements. The conductivity of the compounds was shown to be dependent on the structure. The use of these materials as anodes, in preliminary fuel cell tests has revealed that some compositions have catalytic activity for the direct oxidation of methane. Open cell potentials as high as 1.14V were obtained at 950 degrees C.