Improved thermal expansion and electrochemical performance of La0.4Sr0.6Co0.9Sb0.1O3-δ-Ce0.8Sm0.2O1.9 composite cathode for IT-SOFCs

La0.4Sr0.6Co0.9Sb0.1O3-delta (LSCSb)-xCe(0.8)Sm(0.2)O(1.9) (LSCSb-xSDC, x= 0, 20, 30, 40 and 50 wt%) composite materials have been studied systemically as cathodes for intermediate-temperature solid oxide fuel cells (IT-SOFCs). XRD result shows an excellent chemical compatibility between LSCSb cathode and SDC/LSGM electrolytes. Although electrical conductivity is reduced with the introduction of SDC content, the electrical conductivities of all the composite cathodes are still above 100 S cm(-1) at 300-850 degrees C. Thermal expansion result shows that the increase in SDC content greatly reduces thermal expansion coefficients (TECs) and the TEC for the LSCSb-50SDC cathode attains as low as 13.1 x 10(-6) K-1 at 30-900 degrees C. Polarization resistance (R-p) decreases monotonously with increasing SDC content, and the LSCSb-50SDC cathode shows the lowest polarization with the R-p of 0.086 Omega cm(2) at 700 degrees C. For a 300 mu m thick La0.9Sr0.1Ga0.8Mg0.2O3 (LSGM) electrolyte-supported single cell, the maximum power density (P-max) of the cell with LSCSb-50SDC cathode achieves 432 mW cm(-2) at 700 degrees C. Moreover, the single cell with the LSCSb-50SDC cathode also shows a good cell stability at operating temperature. Above results indicate that LSCSb-50SDC composite material is a potential cathode for IT-SOFCs.