Preparation and electrochemical properties of La_(0.7)Sr_(0.3)FeO_3-Sm_(0.2)Ce_(0.8)O_3 composite cathodes

Perovskite-type La0.7Sr0.3FeO3 (LSF) was synthesized using solid state reaction and the glycine-nitrate process and Sm2O3-doped CeO2 (SDC) using co-precipitation method. LSF-SDC composite cathodes with varied composition and different starting powders, sintered at different temperatures, have been studied as electrodes for CeO2-based fuel cell with AC impedance spectrum at temperatures from 550 ℃ to 800 ℃. The results show that SDC addition greatly improved the performance of LSF cathode. LSF-SDC 50% (mass fraction) cathode sintered at 950 ℃ shows the lowest interfacial area specific resistance (ASR), smaller than 0.2 Ω·cm2 as temperature higher than 700 ℃, and about 10 times lower than pure LSF electrode. The observed high performance of the composite electrode is explained as the catalysis of Ce4+/Ce3+ redox, high ionic conductivity and high triple phase boundary of the electrode.