Highly stable La0.5Sr0.5Fe0.9Mo0.1O3-δ electrode for reversible symmetric solid oxide cells

Reversible solid oxide cells (RSOCs) using identical material as both fuel electrode and air electrode have received extensive attentions due to their simplified fabrication process, increased compatibility between electrolyte and electrode. In this work, Molybdenum doped La0.5Sr0.5Fe0.9Mo0.1O3-δ (LSFMo) symmetric electrode based on RSOCs is firstly designed and synthesized via sol-gel method. The effect of Molybdenum substitution at Fe-site on crystal structure, chemical stability, conductivity and electrochemical performance of La0.5Sr0.5FeO3-δ oxide is thoroughly investigated. The structural stability of La0.5Sr0.5FeO3-δ (LSF) in reducing condition is significantly enhanced after the incorporation of Mo5+/6+ and the conductivity in 5% H2 for LSFMo is ~7 times higher than that of undoped LSF. In addition, the polarization resistance value at 850 °C based on LSFMo/LSGM/LSFMo is 0.08 and 0.09 Ω cm2 in air and wet H2, respectively. At 850 °C and 20%H2O–H2, a peak power density of 640 mW cm−2 is obtained in fuel cell mode, while a current density of −1000 mA cm−2 is attained at 1.3 V in electrolysis mode. Finally, the symmetric cell exhibits an excellent cycling reversible operation in both SOFCs mode and SOECs mode without detectable degradation.