Investigation of cobalt-free perovskite Ba0.95La0.05FeO3−δ as a cathode for proton-conducting solid oxide fuel cells

Cobalt-free perovskite Ba0.95La0.05FeO3−δ (BLF) was synthesized. The conductivity of BLF was measured with a DC four-point technique. The thermal expansion coefficient of the BLF was measured using a dilatometer. The BaZr0.1Ce0.7Y0.2O3−δ (BZCY7) electrolyte based proton conducting solid oxide fuel cells (SOFCs) were fabricated. A composite cathode with BLF + BZCY7 was used to mitigate the thermal expansion mismatch with the BZCY7 electrolyte. The polarization processes of the button cell NiO–BZCY7/BZCY7/BLF + BZCY7 were characterized using the complicated electrochemical impedance spectroscopy technique. The open circuit voltage of 0.982 V, 1.004 V, and 1.027 V was obtained at 700 °C, 650 °C, and 600 °C, respectively, while the peak power density of 325 mW cm−2, 240 mW cm−2, and 152 mW cm−2, was achieved accordingly.

► Cobalt-free perovskite Ba0.95La0.05FeO3−δ (BLF) was studied as a cathode material for SOFCs.
► The conductivity of BLF was measured with a DC four-point technique, showing temperature-dependent property.
► The chemical and thermal compatibilities of cathode and electrolyte were studied. And a composite cathode was used to mitigate the thermal expansion mismatch between electrolyte and cathode layers.
► The electrochemical performances of the cell NiO–BZCY7/BZCY7/BZCY7–BLF were characterized.