B-Site engineering of the nanocomposite perovskite SrCo0.5 <b>−</b> xFeAlx O3 cathode for enhanced ORR kinetics and high-performance low-temperature ceramic fuel cells

Ceramic fuel cells (CFCs) are promising energy conversion devices that efficiently convert chemical energy into electrical energy. However, the development of a cathode with high oxygen reduction reaction (ORR) activity at low temperature (LT) remains the primary bottleneck for the commercialization of CFCs. This work proposes B-site engineering in the perovskite SrCo0.5Fe0.5O3 (SCF) using Al as a dopant to improve the cathode ORR activity for LT operation. The material was synthesized via a sol-gel technique. An electrolyte-supported cell featuring an SrCo0.3Fe0.5Al0.2O3 cathode demonstrates an impressive peak power density of 872 mW/cm2 and lower polarization resistance of 0.162 Ω-cm2 at 520 °C. We attribute this high performance and enhanced ORR activity to an increased number of O-vacancies, resulting from the appropriate doping of Al into SCF and formation of beneficial surface layer. The density functional theory calculations further reveal electronic properties suitable for effective cathodic activity in SrCo0.3Fe0.5Al0.2O3. Our work indicates that B-site engineering is an effective strategy for enhancing the ORR activity and overall performance of CFC cathode at low temperatures.