Enhanced Performance of La _0.7 Sr _0.3 FeO _{3- δ} Cathode for SOFC via Implementation of B-site High-entropy Strategy

As classical cathode materials of solid oxide fuel cell (SOFC), Fe-based perovskite materials are favored for their affordable price, low thermal expansion coefficient and high stability.In this study, B-site high-entropy perovskite oxide La 0.7 Sr 0.3 (FeNiCo) 0.8 Mo 0.1 Ti 0.1 O 3- (LSFNCMT) was prepared by the citric acid-nitrate combustion method.Due to the faster oxygen surface exchange rate of the high-entropy material, the LSFNCMT cathode shows excellent oxygen reduction reaction (ORR) activity with a polarization impedance (R p ) of 0.11 cm 2 at 800 , which is much lower than that of the La 0.7 Sr 0.3 FeO 3- (LSF) cathode (0.31 cm 2 ).Furthermore, the high-entropy material exhibits superior stability due to incorporation of highly acidic Ni, Co, and Mo cations as well as Ti cation with more negative average bonding energy (ABE) of metal-oxygen.In the 22 h-stability test of the symmetric cell with LSFNCMT cathode in the Cr-containing atmosphere, R p only increases from 1.07 cm 2 to 2.98 cm 2 , while R p of the LSF cathode increases from 2.62 cm 2 to 7.90 cm 2 under the same conditions, indicating better Cr-resistance of LSFNCMT due to the high-entropy strategy.The fact that the maximum power density (MPD) of the single cell with LSFNCMT cathode at 800 is 1105.26mWcm -2 , significantly higher than that of LSF cathode (830.74 mWcm -2 ), and R p at 800 is 0.24 cm 2 , lower than that of LSF cathode (0.36 cm 2 ), confirming excellent toxicity resistance of the high-entropy cathode.This study shows that B-position high entropy is an effective way to improve the catalytic activity and chromium resistance of cathode materials.