Synergistically enhancing CO2-tolerance and oxygen reduction reaction activity of cobalt-free dual-phase cathode for solid oxide fuel cells

Abstract

High-performance cathodes with adequate CO2 tolerance are vital for further development of intermediate-temperature solid oxide fuel cells (IT-SOFCs). However, there is always a trade-off between CO2 tolerance and oxygen reduction reaction (ORR) performance for single-phase cathodes. Here, we report a cobalt-free Ba0.6La0.4FeO3-δ-Ce0.8Sm0.2O2-δ (BLF-SDC) dual-phase cathode with excellent ORR activity and CO2 tolerance. Introducing ionic conductor Ce0.8Sm0.2O2-δ (SDC) into the Ba0.6La0.4FeO3-δ (BLF) phase can boost ORR activity due to the extended active sites and enhanced oxygen surface exchange process with a polarization resistance of 0.121 Ω cm2 for the BLF-30% SDC (weight ratio, BLF-30SDC) cathode at 700 °C. The CO2 resistance of the BLF-30SDC composite cathode outperforms BLF cathode by three times at 600 °C. This stability enhancement is owing to low CO2 adsorption of SDC, which is confirmed from thermodynamic calculation. This work indicates that dual-phase mixed conductors can be developed as highly active and stable cathodes for IT-SOFCs.