Towards high performance durable ceramic fuel cells using a triple conducting perovskite cathode

To guarantee the efficient and durable operation of oxygen ion/proton-conducting ceramic fuel cells, the cathode materials need to be versatile in terms of high activity, good CO₂ resistance, and matched thermal expansion behavior with electrolyte, etc. In this study, we substituted 10% Nb to the B-site of parent perovskite-BaCo_0.7Fe_0.2Y_0.1O_3-δ, to form a single-phase material with triple conducting (H⁺/O^2-/e^-) capability as a highly ORR-active cathode. The doped BaCo_0.6Fe_0.2Y_0.1Nb_0.1O_3-δ (BCFYN) shows promising ORR activity due to the optimized oxygen vacancy, improved hydration capacity, and accelerated charge transfer kinetics. The reduction of thermal expansion coefficient (TEC) and enhanced CO₂ resistance also facilitate the cathode durability. As a result, the area-specific resistances of BCFYN electrode at 550 °C for oxygen-ion and proton conducting symmetrical cells were only 0.106 and 0.24 Ω cm², respectively. These results indicate that BCFYN is a highly promising cathode material for both SOFCs and PCFCs.