Performances of Ba0.5Sr0.5Co0.6Fe0.4O3-δ -Ce0.8Sm0.2O1.9 composite cathode materials for IT-SOFC

Composite materials Ba0.5Sr0.5Co0.6Fe0.4O3-delta (BSCF4)-Ce0.8Sm0.2O1.9 (SDC) (BSCF4-SDC) were prepared and characterized as cathode for intermediate temperature SOFC (IT-SOFC). The powder X-ray diffraction (XRD), thermal expansion coefficient (TEC), electrical conductivity and electrochemical property measurement were employed to study the materials. The XRD result proved the reaction between BSCF4 and SDC in BSCF4-SDC. The conductivity of BSCF4-SDC was higher than that of BSCF4; in additions the thermal expansion coefficient of the BSCF4-SDC was about 18% lower than BSCF4 from 30 to 800 deg C in air. Polarization curves and impedance spectra measured at intermediate temperatures showed the BSCF4-SDC electrode yielded lower resistance values than that of BSCF4 electrode. And the addition of 30wt% SDC to BSCF4 had the best electrochemical properties; e.g., polarization resistance of BSCF4-SDC30 was 0.298Omegacm2 at 550 deg C, which was nearly 85% lower than that of BSCF electrode.