Assessment of perovskite-type La_0.8Sr_0.2Sc _xMn_1-xO_3-δ oxides as anodes for intermediateerature solid oxide fuel cells using hydrocarbon fuels

Composites formed by the infiltration of 40 wt% La_0.8Sr _0.2Sc_xMn_1-xO_3-δ (LSSM) oxides (x = 0.1, 0.2, 0.3) into 65% porous yttria-stabilized zirconia (YSZ) are investigated as anode materials for intermediateerature solid oxide fuel cells for hydrocarbon oxidation. The oxygen non-stoichiometry and electrical conductivity of each LSSM-YSZ composite are determined by coulometric titration. As the concentration of Sc increases, the composites show higher phase stability and the electrical conductivity of LSSM is significantly affected by the Sc doping, the non-stoichiometric oxygen content, and oxygen partial pressure (p(O₂)). To achieve better electrochemical performance, it is necessary to add ceria-supported palladium catalyst for operation with humidified CH₄. Anode polarization resistance increases with Sc doping due to a decrease in electrical conductivity. An electrolyte-supported cell with a LSSM-YSZ composite anode delivers peak power densities of 395 and 340 mW cm^-2 at 923 K in humidified (3% H₂O) H₂ and CH₄, respectively, at a flow rate of 20 mL min^-1.