Electrochemical characteristics of LSCF-SDC composite cathode for intermediate temperature SOFC

A kind of composite cathode, La_0.58Sr_0.4Co_0.2Fe_0.8O_3-δ-Ce_0.8Sm_0.2O_2-δ (LSCF-SDC), was presented in this paper. The electrochemical performance of the cathode on the electrolyte of SDC and YSZ coated with a thin SDC (YSZ/SDC) layer was studied by electrochemical impedance spectroscopy (EIS) and cathodic polarization techniques for their potential utilization in the intermediate temperature solid oxide fuel cell (IT-SOFC). Also studied was the relationship between the electro-catalytic characteristics and the electrode microstructure. Results showed that the LSCF-SDC composite electrode performed better on the SDC electrolyte than on the electrolyte of YSZ/SDC. The polarization resistance, R_p, of the cathode on the SDC electrolyte was 0.23 Ω cm² at 700 °C and 0.067 Ω cm² at 750 °C, much lower than the corresponding R_p of the same cathode on the YSZ/SDC electrolyte. At 750 °C, the cathodic overpotential of the composite cathode on the SDC electrolyte was 99.7 mV at the current density of 1.0 A cm^-2.