Designing high-performance quasi-symmetrical solid oxide cells with a facile chemical modification strategy for Sr2Fe2-xWxO6-δ ferrites electrodes with in situ exsolution of nanoparticles

Abstract

The chemical modification of perovskites is one of the most effective design strategies for electrode materials for solid oxide cells. In this work, the tungsten doping in $Sr_{2}Fe_{2−x}W_{x}O_{6−δ}$ shows a significant impact on their physicochemical properties, and it leads to a substantial change of electrochemical properties in the air and reducing conditions, with $Sr_{2}Fe_{1.8}W_{0.2}O_{6−δ}$ (Rp = 0.06 Ω cm2 at 800 °C stable for 100 h in air) and $Sr_{2}Fe_{1.6}W_{0.4}O_{6−δ}$ (Rp = 0.56 Ω cm2 at 800 °C over 100 h in 5 vol% $H_{2}/Ar$) being the best air and fuel electrode candidates, respectively. We have proposed an attractive design of high-performance quasi-symmetrical solid oxide cells with $80%Sr_{2}Fe_{1.8}W_{0.2}O_{6−δ}+20%GDC$ | LSGM | $80%Sr_{2}Fe_{1.6}W_{0.4}O_{6−δ}+20%GDC$, demonstrating excellent power outputs ($874 mW cm^{−2}$ at 850 °C in wet $H_{2}$) and good current density of 743 mA $cm^{−2}$ at 1.5 V in electrolysis mode at 750 °C. A good performance of 451 mW $cm^{−2}$ was also recorded in wet $CH_{4}$ at 800 °C. The in situ exsolved metallic iron nanoparticles decorated on the $Sr_{2}Fe_{1.6}W_{0.4}O_{6−δ}$ anode contribute to the excellent electrochemical performance of cells. This study provides a successful scenario for designing high-performance symmetrical solid oxide cells with a facile chemical modification strategy for ferrites electrodes with in situ exsolution of nanoparticles.