Effect of Cation Demixing on the Electrochemical Performance of LSCFO Cathodes for SOFCs
The use of mixed conducting cathodes such as La1-xSrxCo1-yFeyO3 (LSCFO) improves considerably the performance of the cell. However, one of the most common degradation mechanisms of LSCF reported in the literature is the segregation of Sr.
This work aims at studying the effect of Sr segregation on the electrochemical properties of LSCFO cathodes. LSCFO oxide powders were prepared by solid state reaction and deposited on Ce1-xGdxO2 electrolytes by spin coating. Afterwards, these cells were heat treated at conditions that facilitate the formation of Sr segregates. The electrochemical properties of the cathodes were monitored by electrochemical impedance spectroscopy, while the microstructure was characterized by Scanning Electron Microscopy, Transmission Electron Microscopy, Energy Dispersive Spectroscopy, and X-Ray Diffraction. The relation between the Sr segregation phenomena and the changes in the electrochemical performance of the cathode is discussed.