A novel metal supported Solid Oxide Fuel Cell has been developed, capable of operating at temperatures of 500-600°C. The rationale behind the materials used to construct this fuel cell type is given, and results presented from cell and short stack testing, including durability and thermal cycling trials. This new fuel cell variant is shown to be tolerant of carbon monoxide durable, robust to thermal and redox cycling, and capable of delivering technologically relevant power densities.

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Abstract. Excellent thermal and mechanical stability coupled with low cost have attracted interest in the application of the cubic perovskite SrTiO~ as a substrate material in supported SOFC designs. For such designs increased substrate conductivity is beneficial. A method of improving conductivity is by cation substitution. Due to the constraint of electro-neutrality, oxygen ion vacancies can be generated in strontium titanate by successful substitution of tetra-valent titanium ions with divalent metal ions (M) to produce materials of stoichiometry SrTi~, ~,M~O,3~. By raising the intrinsic oxygen vacancy concentration in this manner there is an increase in available hopping sites. The increase in vacant sites facilitates oxygen transport through the crystal hence increases the potential for oxide ion conductivity. The synthesis of such materials was carried out by standard solid-state techniques using calcium and magnesium as dopants. B site solubility limits for both species were obtained by powder X-ray diffraction. The conductivity behaviour of successful phase pure compounds was investigated using AC impedancc spectroscopy and four point DC measurements across a range of pO., values. The B site solubility limit for magnesium was found to lie between 5 and 7 %. SrTi,~sMg~r,5029s exhibited increased conductivity and a~ducoJ activation energy for conduction as compared to undopcd strontium titanate. DC measurements lbr the same material confirmed the increased p-type behaviour of the system associated with magnesium doping at high oxygen partial pressures. IntroductionSolid oxide l~hcl cells (SOFCs) are currently at the forefront of research into new generations of energy conversion systems owing to their high efficiency, versatility and environmentally friendly nature. Considerable attention has been focused on these systems, particularly on the electrode front, where materials with improved propcrties are being sought. This study is part of a more general goal to develop new anode materials and designs which negate the problems associated with the current Ni/YSZ cermet anode; notably sintering of Ni at operating temperatures, and coking and sulphur poisoning when using natural gas as fuel [1 ].Perovskites oxide materials possess general stoichiomerry ABO~. Conventionally the A cation is larger than the B cation. In the archetype the A cation has an oxidation state of +2 and the B cation has oxidation state +4. These materials comprised of 3 different ionic species,

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