Effects of humidity on Ba0.9Co0.7Fe0.2Nb0.1O3−δ cathode performance and durability of Solid Oxide Fuel Cells

Solid Oxide Fuel Cells (SOFCs) cathode often suffers from degradation resulting from different contaminations, such as water vapor from air, when operated under the realistic environments. In this work, we demonstrate an excellent water vapor tolerant Ba0.9Co0.7Fe0.2Nb0.1O3−δ (BCFN) cathode for SOFCs. The concentration effects of humidity on BCFN cathode performance including oxygen reduction reaction (ORR) kinetics and durability have been studied. The X-ray diffraction measurement indicates that humidity has no observable effects on BCFN materials. The electrochemical performance change in BCFN cathode seems to be more sensitive to the humidity at a lower temperature such as 650 °C than that at 800 °C. A low polarization resistance of 0.069 Ω cm2 at 650 °C is obtained in 3% water vapor, and then the polarization resistance increases with increase of water vapor content. Furthermore, the electrochemical impedance spectra indicate that BCFN cathode contaminated by higher humidity can be recovered by purging air again.