Optimizing La1-xSrxFeO3-δ electrodes for symmetrical reversible solid oxide cells

Abstract

Reversible solid oxide cells (RSOCs) are prone to material thermal property mismatching problems between electrodes and electrolyte, which greatly reduces their energy efficiency and causes irreversible performance degradation. One solution is to develop symmetrical RSOCs (SRSOCs) employing identical electrode materials to effectively address thermal property mismatching related issues and also simplify the manufacturing process. Herein, La1-xSrxFeO3-δ (x = 0–0.20) perovskites are developed and applied as both fuel and air electrode materials for SRSOCs for the first time. The impact of Sr substitution for La on the crystal structures, conductivities and electrochemical performance of LaFeO3 oxides is systematically investigated. It is found, after doping with Sr, overall properties of the LaFeO3 oxides show an obvious improvement, especially for the sample of La0·9Sr0·1FeO3-δ (LSF9010). The peak power density of SRSOCs featuring LSF9010 can stand at 0.575 W cm−2 at 800 °C under the solid oxide fuel cell (SOFC) working model. Under solid oxide electrolysis cell (SOEC) model, the current density stands at 0.84 A cm−2 at 800 °C and 1.5 V. More importantly, the La0·9Sr0·1FeO3-δ symmetrical cell can operate steadily for 128 h under SOFC mode and 25 h under SOFC-SOEC cycle mode, respectively, with almost no performance degradation found. The outcomes of the current study show that the developed LSF9010 may be used as an outstanding multifunctional electrode material in SRSOCs.