Synthesis and assessment of la_0.8Sr_0.2Sc _yMn_1-yO_3-δ as cathodes for solid-oxide fuel cells on scandium-stabilized zirconia electrolyte

Perovskite-type La_0.8Sr_0.2Sc_yMn _1-yO_3-δ oxides (LSSMy, y=0.0-0.2) were synthesized and investigated as cathodes for solid-oxide fuel cells (SOFCs) containing a stabilized zirconia electrolyte. The introduction of Sc³⁺ into the B-site of La_0.8Sr_0.2MnO_3-δ (LSM) led to a decrease in the oxides' thermal expansion coefficients and electrical conductivities. Among the various LSSMy oxides tested, LSSM0.05 possessed the smallest area-specific cathodic polarization resistance, as a result of the suppressive effect of Sc³⁺ on surface SrO segregation and the optimization of the concentration of surface oxygen vacancies. At 850°C, it was only ∼0.094Ωcm² after a current passage of 400mA cm^-2 for 30 min, significantly lower than that of LSM (∼0.25 Ω cm²). An anode-supported cell with a LSSM0.05 cathode demonstrated a peak power density of 1300mWcm^-2 at 850°C. The corresponding value for the cell with LSM cathode was 450mWcm^-2 under the same conditions. The LSSM0.05 oxide may potentially be a good cathode material for IT-SOFCs containing doped zirconia electrolytes.