Improving Stoichiometry and Processing of LSCF Oxygen Electrode for SOFC

La1-xSrxCo0.2Fe0.8O3-δ was used as SOFC cathode by using powders of different stoichiometry. The manufacturing of functional layer was carried our by atmospheric plasma spraying (APS) using TriplexPro gun. The processing was improved to obtain microstructure exhibiting high gas permeability and no degradation of the powders while attaining high production rates. Dwell time of the particles in the plasma was established as the critical factor for degradation and permeability. The improved functional coatings had a porosity of about 20 vol%. The CTE in air flow at 800°C was, however, 15.6×10-6 K-1. Electrochemical tests on SOFC cells having cathodes of different stoichiometry with improved processing were conducted. These cells were produced using metal supported design, had YSZ as electrolyte and NiO+YSZ as anode. No interlayer (such as CGO) between YSZ and LSCF cathode was introduced. At 800°C, power densities of above 640 mW/cm2 at 0.7V were recorded with H2/air for cell having La0.60Sr0.40Co0.2Fe0.8O3-δ as cathode. Cells consisting of La0.58Sr0.4Co0.2Fe0.8O3-δ and La0.78Sr0.2Co0.2Fe0.8O3-δ had 479 and 496 mW/cm under similar conditions. Using equivalent circuit diagrams, the contributions of different polarizations on the cell performance were separated and cathodes were compared. La0.60Sr0.40Co0.2Fe0.8O3-δ was found to have the best electrochemical performance followed by La0.58Sr0.40Co0.2Fe0.8O3-