A CO2-tolerant SrCo0.8Fe0.15Zr0.05O3−δ cathode for proton-conducting solid oxide fuel cells

Abstract

SrCo_0.8Fe_0.2O_3−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. SrCo_0.8Fe_0.15Zr_0.05O_3−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|BaZr_0.1Ce_0.7Y_0.1Yb_0.1O_3−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.