Nanocrystalline doped lanthanum cobalt ferrite and lanthanum iron cobaltite-based composite cathode for significant augmentation of electrochemical performance in solid oxide fuel cell

Abstract

Sr-doped lanthanum cobalt ferrite (La0.54Sr0.40Co0.20Fe0.80O3−δ) and lanthanum iron cobaltite (La0.54Sr0.40Fe0.20Co0.80O3−δ)-based mixed ionic and electronic conducting solid oxide fuel cell cathodes are synthesized by autocombustion technique. In order to examine the electrochemical activity including thermal matching with the adjacent cell components, a composite cathode comprising of both the ferritic and cobaltite system is prepared using mechanical mixing. Powder characterizations for cobaltite and ferritic-based perovskite revealed nanocrystallinity (15–30 nm) with particulate size ranging 50–100 nm. Anode-supported half cell with suitable doped ceria based interlayer on the top of the electrolyte and developed composite cathode augments the current density to 3.98 Acm−2 at 0.7 V at 800 °C. The oxygen reduction reaction kinetics of such composite cathode shows high exchange current density of 1.16 Acm−2 with relatively low electrode polarization of 0.02 Ωcm2 at 800 °C. The electrochemical performance is clinically correlated with the cell microstructure exhibiting minimum SrO diffusion at the electrode-electrolyte interface.