Flexible A-site doping La_(0.6-x)M_xSr_(0.4)Co_(0.2)Fe_(0.8)O_3 (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

摘要

To address both challenges of insufficient oxygen vacancies and excessive interface resistance in intermediatetemperature 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 (R-p) and activation energy (E-a) is superior than most of other LSCF doping strategies. The R-p and E-a 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 degrees C. Both R-p and power density suggest the effectiveness of Bi doping strategy for developing cathode materials in IT-SOFCs.