The characteristic of strontium-site deficient perovskites SrxFe1.5Mo0.5O6−δ (x = 1.9–2.0) as intermediate-temperature solid oxide fuel cell cathodes

Abstract

As the cathodes for intermediate-temperature solid oxide fuel cells (IT-SOFCs), A-site deficient SrxFe1.5Mo0.5O6−δ (x = 1.9–2.0) (SxFM) materials have been successfully synthesized using the sol–gel combustion method. In the perovskite structure of these oxides, the unit cell varies from pseudocubic to cubic with increasing deficiency. Thermal expansion coefficient of SxFM has also been measured and compared with that of Scandium-stabilized zirconium (ScSZ) electrolyte. X-ray photoelectron spectroscopy (XPS) results indicate that the Sr-deficiency has changed the proportion of Fe2+/Fe3+ and Mo6+/Mo5+ ratios, which directly influences the conductivity of SxFM materials. S1.950FM possesses the largest electrical conductivity and the lowest polarization resistance (Rp) among all the samples. The maximum power densities of a single cell with the S1.950FM cathode reaches 1083 mW cm−2, and the area specific resistance value is 0.17 Ω cm2 at 800 °C. These results indicate that the A-site deficiency could promote the electrochemical performance of SFM materials as cathodes for IT-SOFCs.