Performance of YBa₂Cu₃O_7-δ-La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δ composite cathode for intermediate-temperature solid oxide fuel cells

In this work, different contents of La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δ (10, 20, 30 and 40 wt% LSCF) are added into YBa₂Cu₃O_7-δ (YBC) to investigate its effect on the performance of solid oxide fuel cell cathode. The result shows that with addition of 30 wt% LSCF, the polarization resistance is decreased from 0.137 to 0.044 Ω cm², and the output of the single cell is increased about 50% at 800 °C. O₂ temperature-programmed desorption and electrical conductivity test show that the oxygen exchange capacity and conductivity of YBC-LSCF are greatly improved from 600 to 800 °C. The equivalent circuit fitting results of electrochemical impedance spectroscopy curves under the different oxygen partial pressures of 0.05, 0.1, 0.21 and 1 atm indicate that the resistance associated with charge transfer and gas transport in the composite cathode are about 80% and 60–80% decreased, respectively. It is found that the low conductivity and poor oxygen adsorption behavior may be the two obstacles for using YBC as a cathode material. It also can be seen that by taking the advantages of LSCF, the drawbacks of YBC are largely remedied and the synergistic effect is achieved.