Degradation of cobalt-free Ba0.95La0.05FeO3-δ cathode against CO2-H2O and Ce0.9Gd0.1O2-δ modification

Under actual operating conditions, cathode materials of Solid Oxide Fuel Cell (SOFC) tend to react with CO2 and/or H2O in air, resulting in degraded performances and stabilities. Here, effects of CO2 and H2O on Ba0.95La0.05FeO3-delta (BLF) cathode are systematically discussed by X-ray diffraction patterns (XRD), electrochemical impedance spectra (EIS) and scanning electron microscope (SEM). The results show that BaCO3 can be formed at 400 degrees C in a simulated air atmosphere. The content of CO2 and H2O has a significant influence on the polarization resistance (R-p) of BLF, the R-p of BLF is 0.161 Omega.cm(2) in fresh air and 0.649 Omega.cm(2) in 3% CO2-5% H2O-92% Air at 700 degrees C, respectively. But such degradation is reversible by switching working gas into fresh air again. In addition, we propose two alternative ways to improve tolerance of BLF cathode against CO2 and H2O: surface coating Ce0.9Gd0.1O2-delta (GDC) nano -particles on BLF cathode via spray-drying method and mechanical mixing GDC with BLF cathode. Compared with mechanical mixing, surface coating method is more advantageous in lowering the R-p of BLF cathode, which keeps 0.160 Omega.cm(2) with 3% CO2-5% H2O-92% Air at 700 degrees C for 24 h. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.