Facile Deficiency Engineering in a Cobalt-Free Perovskite Air Electrode to Achieve Enhanced Performance for Protonic Ceramic Fuel Cells

As a crucial component responsible for the oxygen reduction reaction (ORR), cobalt-rich perovskite-type cathode materials have been extensively investigated in protonic ceramic fuel cell (PCFC). However, their widespread application at a commercial scale is considerably hindered by the high cost and inadequate stability. In response to these weaknesses, the study presents a novel cobalt-free perovskite oxide, Ba0.95La0.05(Fe0.8Zn0.2)0.95O3-delta (BLFZ0.95), with the triple-conducting (H+|O2-|e-) property as an active and robust air electrode for PCFC. The B-site deficiency state contributes significantly to the optimization of crystal and electronic structure, as well as the increase in oxygen vacancy concentration, thus in turn favoring the catalytic capacity. As a result, the as-obtained BLFZ0.95 electrode demonstrates exceptional electrochemical performance at 700 degrees C, representing extremely low area-specific resistance of 0.04 omega cm2 in humid air (3 vol.% H2O), extraordinarily high peak power density of 1114 mW cm-2, and improved resistance against CO2 poisoning. Furthermore, the outstanding long-term durability is achieved without visible deterioration in both symmetrical and single cell modes. This study presents a simple but crucial case for rational design of cobalt-free perovskite cathode materials with appreciable performance via B-site deficiency regulation. A novel cobalt-free perovskite oxide with distinctive B-site deficiency tuning, Ba0.95La0.05(Fe0.8Zn0.2)0.95O3-delta (BLFZ0.95) is designed and developed as a cathode for protonic ceramic fuel cells (PCFCs). Benefiting from the optimized crystal and electronic structure and enhanced oxygen vacancy concentrations achieved through B-site deficiency, the BLFZ0.95 cathode demonstrates exceptional electrochemical activity and durability, marking a significant milestone in advanced perovskite-based cathodes for PCFCs. image