Alternative B-site-doped La0.6Sr0.4Co0.2Fe0.8-xMxO3 (M = Ni, Cu, Nb; x = 0, 0.1, 0.2) as innovative cathode material for LT-SOFC with enhanced charge transfer and oxygen ion diffusion

Abstract

Although La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) owns a high level of maturity as a cathode material for intermediate and high-temperature SOFCs, there still exists tremendous potential for it to be employed under an efficient low-temperature working conditions. Since the charge transfer and oxygen ions diffusion act as pivotal obstacles to realizing the operation of LT-SOFCs (below 600 °C), the B-site doping elements (Ni, Cu, Nb) in commercial LSCF are selected using the first-principles calculation. Based on the theoretical findings, the novel Cu-doped La0.6Sr0.4Co0.2Fe0.8-xCuxO3 (LSCFCx, x = 0, 0.1, 0.2) cathode materials are synthesized with exploring the phase structure, valence states of the elements, and thermogravimetric properties. Among different doping elements, Cu doping could facilitate the electrochemical performance of LSCFCx cathode by the enhancement of electrons at B-site and enrichment the of oxygen vacancies. Arising from the inspiring charge transfer and the accelerating oxygen ion transportation, Cu-substitution yields superior activity than other LSCF doping elements. The polarization resistant and activation energy values for LSCFC0.2 cathode attenuates more than 71% and 35% in contrast to the undoped LSCF cathode, respectively. The maximal power density of the anode-supported single cells utilizing LSCFC0.2 cathode outputs 0.594 W∙cm‐2 at 600 °C and promotes over 41% than commercial LSCF at the same condition. These results conclusively point to a practical Cu-doping strategy for the development of highly efficient cathodes for LT-SOFCs.