Electrochemical Performance and Enhancement of Hydration Kinetics on BaCo0.7Fe0.2Zr0.1O3-d Cathode for Protonic Ceramic Fuel Cells

Protonic ceramic fuel cells (PCFCs) are gaining increasing attention for their impressive energy conversion efficiency. Nevertheless, identifying a suitable cathode remains a major hurdle for the widespread commercialization of PCFCs. Herein, the A-site cation-deficient perovskite Ba1-x Co0.7Fe0.2Zr0.1O3-d (B1-x CFZ, x = 0, 0.05, 0.1, and 0.15) has been explored as a prospective cathode for PCFCs, which effectively reduced the polarization resistance (R p) and enhanced the hydration capability of the cells. The polarization resistance of B0.9CFZ with 10% deficiency decreases to 0.105 ? cm2 at 700 & DEG;C in dry air, & SIM;41.7% lower than that of pristine BCFZ. Additionally, when exposed to humid air with 5 vol % steam, the B0.9CFZ cathode demonstrates a further smaller polarization resistance of 0.083 ? cm2 at 700 & DEG;C, about 21% lower than that in dry air. This improvement can be attributed to an improvement in proton hydration kinetics resulting from an increase in oxygen vacancy concentration with barium deficiency, which accelerates the formation of proton defects during the oxygen reduction reaction process. The single cell consisting of Ba0.9Co0.7Fe0.2Zr0.1O3-d|BaCe0.7Zr0.1Y0.1Yb0.1O3-d|NiO-BaCe0.7Zr0.1Y0.1Yb0.1O3-d remains stable when operated at a current density of 300 mA cm-2 for 100 h. Overall, this research presents an effective methodology for designing high-performance cathodes that enhance the efficiency of PCFCs.