The characteristic of strontium-site deficient perovskites Sr _xFe_1.5Mo_0.5O_6-δ (x = 1.9-2.0) as intermediate-temperature solid oxide fuel cell cathodes

As the cathodes for intermediate-temperature solid oxide fuel cells (IT-SOFCs), A-site deficient Sr_xFe_1.5Mo _0.5O_6-δ (x = 1.9-2.0) (S_xFM) 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 S _xFM 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⁺/Mo ⁵⁺ ratios, which directly influences the conductivity of S _xFM materials. S_1.950FM possesses the largest electrical conductivity and the lowest polarization resistance (R_p) among all the samples. The maximum power densities of a single cell with the S _1.950FM 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.