La substituted Sr2MnO4 as a possible cathode material in SOFC

Sr2−xLaxMnO4+δ (x = 0.4, 0.5, 0.6) oxides were studied as the cathode material for solid oxide fuel cells (SOFC). The reactivity tests indicated that no reaction occurred between Sr2−xLaxMnO4+δ and CGO at annealing temperature of 1000 °C, and the electrode formed good contact with the electrolyte after being sintered at 1000 °C for 4 h. The total electrical conductivity, which has strong effect on the electrode properties, was determined in a temperature range from 100 to 800 °C. The maximum value of 5.7 S cm−1 was found for the x = 0.6 phase at 800 °C in air. The cathode polarization and AC impedance results showed that Sr1.4La0.6MnO4+δ exhibited the lowest cathode overpotential. The area specific resistance (ASR) was 0.39 Ω cm2 at 800 °C in air. The charge transfer process is the rate-limiting step for oxygen reduction reaction on Sr1.4La0.6MnO4+δ electrode.