Plasma Sprayed LSCF Oxygen Electrode for SOFC

La_1-xSr_xCo_0.2Fe_0.8O_3-δ deposits, of different stoichiometry, were fabricated for SOFC oxygen electrode using atmospheric plasma spraying (APS) with TriplexPro gun. The spraying conditions were developed by correlating, plasma jet characteristics (enthalpy and velocity), in-flight particle properties (temperature and velocity) and deposit quality (phase composition, porosity, coefficient of thermal expansion, electrochemical testing). The optimal cathode deposits exhibited a porosity of about 20 vol.%. The CTE in air flow at 800 °C was, however, 15.6 x 10^-6 K^-1 and it was independent of the processing conditions. Electrochemical tests for cathodes were conducted on SOFCs that were produced following metal supported design and had YSZ as electrolyte and NiO+YSZ as anode. At 800 °C, power densities of above 640 mW/cm² at 0.7 V were recorded with H₂/air for cell having La_0.60Sr_0.40Co_0.2Fe_0.8O_3-δ as cathode. Cells consisting of La_0.58Sr_0.4Co_0.2Fe_0.8O_3-δ and La_0.78Sr_0.2Co_0.2Fe_0.8O_3-δ had 479 and 496 mW/cm² under similar conditions. Using equivalent circuit diagrams the contribution of different polarizations on the cell performance were separated and cathodes were compared. La_0.60Sr_0.40Co_0.2Fe_0.8O_3-δ was found to have the best electrochemical performance followed by La_0.58Sr_0.40Co_0.2Fe_0.8O_3-δ and La_0.78Sr_0.20Co_0.2Fe_0.8O_3-δ.