A CO2-tolerant SrCo0.8Fe0.15Zr0.05O3−δ cathode for proton-conducting solid oxide fuel cells
SrCo0.8Fe0.2O3−δ (SCF) exhibits high ionic–electronic conductivity. However, its instability in the presence of CO2 restricts its application in electrochemical devices. In this study, 5 mol% zirconium was introduced into SCF to improve its structural stability and CO2 tolerance. SrCo0.8Fe0.15Zr0.05O3−δ (SCFZ) showed metallic electrical conductivity above 500 °C. Furthermore, X-ray diffraction and CO2-temperature programmed desorption experiments indicated that SCFZ possessed adequate structural stability and CO2 tolerance. The oxygen reduction activity and CO2 tolerance were studied using a symmetrical cell, SCFZ|BaZr0.1Ce0.7Y0.1Yb0.1O3−δ (BZCYYb)|SCFZ. The electrochemical performances of the SCFZ material as a cathode were investigated systematically for proton-conducting solid oxide fuel cells (H+-SOFCs) with a configuration of NiO–BZCYYb|BZCYYb|SCFZ–BZCYYb. The output of 712 mW cm−2 at 700 °C and a durability test of over 300 h indicated that SCFZ had significant structural stability and CO2-tolerance.