Preparation and performance of triple-layer graded LaBaCo₂O _5+δ-Ce_0.8Sm_0.2O_1.9 composite cathode for intermediate-temperature solid oxide fuel cells

The triple-layer graded LaBaCo₂O_5+δ-Sm _0.2Ce_0.8O_1.9 (LBCO-SDC) composite cathode was prepared by screen-printing method for intermediate-temperature solid oxide fuel cells. The result of X-ray diffraction indicated the LBCO cathode was chemically stable with the SDC electrolyte. Through optimizing the composition and microstructure, the electrochemical performance of cathode was significantly improved. For triple-layer graded LBCO-SDC composite cathode, the area-specific resistance (ASR) values were 0.881 Ω cm² at 600 °C, 0.174 Ω cm² at 700 °C and 0.047 Ω cm² at 800 °C in air, about 14.8%, 41.0% and 65.7% lower than that of the monolayer LBCO cathode, respectively. The cathodic overpotential was also decreased from 51.0 mV for the monolayer cathode to 33.6 mV at a current density of 0.20 A cm^-2 at 700 °C. The graded composite cathode showed great potential in improving the cathode performance for IT-SOFCs.