Ta-Doped SrCoO3-δ as a Promising Bifunctional Oxygen Electrode for Reversible Solid Oxide Fuel Cells: A Focused Study on Stability
The present work reports a thorough investigation into structural, thermal, electrical and electrochemical properties of 10 mol% Ta-doped SrCoO3-δ (denoted as SCT10) as a promising bifunctional oxygen electrode for intermediate-temperature reversible solid oxide fuel cells. The high-temperature X-ray diffraction (HT-XRD) and high-temperature neutron power diffraction (HT-NPD) studies reveal that SCT10 exhibits a single primitive cubic phase at 200 oC. The thermogravimetric analysis (TGA) and HT-NPD show consistent results of oxygen nonstoichiometry and oxidation-state of Co-ions as a function of temperature. More importantly, the dependency of electronic conductivity and electrochemical activity on temperature, partial pressure of oxygen and time unequivocally suggests that SCT10 is a better and more stable bifunctional oxygen electrode than its rivalry 10 mol% Nb-doped SCO (SCN10), making it more attractive for practical applications.