Fabrication and characterization of solid oxide fuel cell cathodes made from nano-structured LSCF-SDC composite feedstock

Composite La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF) and Ce0.8Sm0.2O1.9 (SDC) cathodes for solid oxide fuel cells (SOFCs) were fabricated by axial-injection plasma spraying. Fine mixing of the ceramic phases was achieved by using a nano-structured feedstock that contained both phases agglomerated together in larger particles. Preliminary investigations explored the effects of varying the process parameters, and cathodes were characterized by XRD and SEM. Metal-supported symmetrical cells were made with several promising sets of process parameters, and the polarization resistance was measured from 550 °C to 750 °C. The cathode with the highest electrochemical performance was incorporated into a fuel cell with a yttria-stabilized zirconia (YSZ) electrolyte and a nickel-YSZ anode. A fuel cell with a coarsely-mixed composite cathode was also fabricated, and the effect of the cathode microstructure on cell impedance was studied using the analysis of differential impedance spectra.