Flexible A-site doping La0.6-xMxSr0.4Co0.2Fe0.8O3 (M=Ca, Ba, Bi; x=0, 0.1, 0.2) as novel cathode material for intermediate-temperature solid oxide fuel cells: A first-principles study and experimental exploration

Abstract

To address both challenges of insufficient oxygen vacancies and excessive interface resistance in intermediate-temperature solid oxide fuel cells (IT-SOFCs), in this study, we apply the first-principle density functional study to choose the A-site cation doping M(M = Ca, Ba, Bi) for conventional La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) and find that Bi doping could produce the smallest generation energy of oxygen vacancy. Then novel Bi-doped La0.6-xBixSr0.4Co0.2Fe0.8O3 (LBSCFx, x = 0,0.1,0.2) cathode materials are investigated, revealing Bi3+ doping can promote the electrochemical performance of LBSCFx cathode by the enrichment of oxygen vacancies and the triple-phase boundaries. Attributed to the accelerated oxygen transportation and the increased oxygen reduction reaction sites, the effectiveness of Bi3+ doping LSCF on the reduction of polarization resistant (Rp) and activation energy (Ea) is superior than most of other LSCF doping strategies. The Rp and Ea values of LBSCF0.2 are reduced more than 58% and 27% compared to that of undoped LSCF respectively, and the maximum power density of the anode-supported single cells based on LBSCF0.2 outperforms 1 W⋅cm−2 at 750 °C. Both Rp and power density suggest the effectiveness of Bi doping strategy for developing cathode materials in IT-SOFCs.