A free-cobalt barium ferrite cathode with improved resistance against CO2 and water vapor for protonic ceramic fuel cells

Abstract

The triple conducting (electron, oxygen-ion and proton) cathode is promising for protonic ceramic fuel cells (PCFCs). Heavy doping of Fe can impel BaZr 0.9 Y 0.1 O 3-δ to cross the electronic percolation threshold, forming the triple-conducting BaFe 0.8 Zr 0.1 Y 0.1 O 3-δ (BFZY) material. The partial A-site substitution with La is also designed to further optimize the properties of BFZY. Herein, a systematic study on Ba 0.95 La 0.05 Fe 0.8 Zr 0.1 Y 0.1 O 3-δ (BLFZY) cathode is conducted for searching potential free-cobalt PCFC cathodes with good tolerance for both CO 2 and water vapor. The XRD result indicates that BLFZY maintains stable cubic perovskite structure. The comprehensive analysis based on XRD, TG and TPD-CO 2 reveals that the BLFZY cathode exhibits an excellent tolerance for CO 2 and water vapor. The La doping also has a positive influence on the thermal expansion coefficient, electrical conductivity, and electrocatalytic activity. The anode-supported single cell with single-phase BLFZY cathode achieves a peak power density of 305 mW cm −2 and polarization resistance of 0.492 Ω cm 2 at 600 °C and maintains steady power output in the short-term durability test. This indicates that the BLFZY material is a good cathode candidate for PCFCs. • BLFZY shows good tolerance for both CO 2 and water vapor. • La dopant is favorable to reducing TEC and increasing electrical conductivity. • A peak power density of 305 mW cm −2 is reached at 600 °C.