Electrochemical characterization of La_(0.6)Ca_(0.4)Fe_(0.8)Ni_(0.2)O_3 cathode on Ce_(0.8)Gd_(0.2)O_(1.9) electrolyte for IT-SOFC

摘要

For Solid Oxide Fuel Cells (SOFCs) to become an economically attractive energy conversion technology, suitable materials and structures which enable operation at lower temperatures, while retaining high cell performance, must be developed. Recently, the perovskite-type La_(0.6)Ca_(0.4)Fe_(0.8)Ni_(0.2)O_3 oxide has shown potential as an intermediate temperature SOFC cathode. An equivalent circuit describing the cathode polarization resistances was constructed from analyzing impedance spectra recorded at different temperatures in oxygen. A competitive electrode polarization resistance is reported for this oxygen electrode using a Ce_(0.8)Gd_(0.2)O_(1.9) electrolyte, determined by impedance spectroscopy studies of symmetrical cells sintered at 800 ℃ and 1000 ℃. Scanning electron microscopy (SEM) studies of the symmetrical cells revealed the absence of any reaction layer between cathode and electrolyte, and a porous electrode microstructure even when sintered at a temperature of only 800 ℃. The performance of this cathode shows favorable oxygen reduction reaction (ORR) properties potentially making it an excellent choice for IT-SOFC application.