Highly promoted performance of triple-conducting cathode for YSZ-based SOFC via fluorine anion doping

One of the most important factors to commercialized yttria-stabilized zirconia (YSZ)-based solid oxide fuel cell (SOFC) is a highly active mixed-conducting cathode at reduced temperatures. Herein, we propose a new strategy of fluorine anion (F−) doping to enhance electrochemical performance of the H+/O2−/e triple-conducting BaCo0.4Fe0.4Zr0.1Y0.1O3-δ (BCFZY) perovskite cathode for YSZ-based SOFCs. The F−-doped BCFZY as BaCo0.4Fe0.4Zr0.1Y0.1O2.95-δF0.05 (BCFZYF) retained the cubic structure with better symmetry. The doping of minor fluorine in oxygen-site was found to increase the oxygen exchange capability and thus oxygen reduction reaction (ORR) catalytical activity, as reflected by lower area specific resistance (ASR) of cathode on symmetrical cells. Maximum power density of 786 mWcm−2 was achieved at 800 °C for anode-supported single cell with BCFZYF cathode, being 1.7 times higher than that with BCFZY cathode. Furthermore, the single cell with BCFZYF cathode demonstrated excellent stability without any degradation of current density over 200 h at 700 °C. The present work clarifies that the fluorine doping strategy is highly effective to promote the ORR activity of the triple-conducting BCFZY cathode for state-of-the-art oxygen-conducting SOFC.