Sr and Fe co-doped Ba2In2O5 as a new proton-conductor-derived cathode for proton-conducting solid oxide fuel cells

Abstract

BaSrInFeO5 (BSIF), a new cathode material for proton-conducting solid oxide fuel cells (SOFCs), is designed based on the modification of the Ba2In2O5 proton conductor with Sr and Fe cations. Compared with the Ba2In2O5 proton conductor tailored with only Fe cations (Ba2InFeO5, BIF), doping Sr can improve the chemical stability and also benefit the formation of oxygen vacancies. The proton mobility is also improved with Sr-doping, which is confirmed by first-principles calculations and experimental studies. An H-SOFC using the BSIF cathode generates a relatively high peak power density of 1192 mW cm-2 at 700 oC, which is superior to many cells in previous reports. First-principles calculations find that the cathode oxygen reduction reaction (ORR) energy barrier for BSIF is significantly lower than that for BIF. Although Ba2In2O5 is less studied, the derived cathode materials can still present decent performance, probably offering new material selections for H-SOFCs.