Combustion synthesis and characterization of LSCF-based materials as cathode of intermediate temperature solid oxide fuel cells

Nanocrystalline SOFC cathode materials of perovskite family, La1-xSrxM1-yCoyO3, where 0<= 0.5, 0<= 0.8 (M is transitional metal = Mn or Fe), have been synthesized at a relatively low temperature by combustion synthesis using alanine as a novel fuel. Detailed X-ray powder diffraction analyses show 47-96% phase purity in the as-synthesized powder and upon calcination at similar to 825 degrees C single-phase material is obtained wherein the nanocrystallinity (crystallite size similar to 19-24 nm) is retained. Densification studies of the materials are carried out within 900-1100 degrees C. The coefficient of thermal expansion (CTE) of these cathodes is measured. Electrical conductivity of the cathodes sintered at different temperatures are measured in the temperature range 700-900 degrees C and correlated with the density of the sintered materials. The electrochemical performances of Ni-YSZ anode-supported SOFC having YSZ electrolyte (similar to 10 mu m) with CGO interlayer (similar to 15 mu m) are studied with the developed cathodes in the temperature range 700-800 degrees C using H-2 as fuel and oxygen as oxidant. Highest current density of similar to 1.7 A/cm(2) is achieved during testing at 800 degrees C measured at 0.7 V with a cathode composition of La0.5Sr0.5Co0.8Fe0.2O3, Precipitation of nanocrystalline grains over the core grains in porous microstructure of this cathode might be one of the reasons for such high cell performance. (C) 2008 Elsevier Ltd. All rights reserved.