Cobalt-Free Perovskite Oxide La0.6Sr0.4Fe0.8Ni0.2O3−δ as Active and Robust Oxygen Electrode for Reversible Solid Oxide Cells

Reversible solid oxide cells have received increasing attention due to high efficiency. Cobalt-free perovskite electrode has compatible thermal expansion coefficient matching with the electrolyte and the reversible operation to inhibit the segregation of Sr. Herein a novel cobalt-free La0.6Sr0.4Fe0.8Ni0.2O3−δ perovskite is developed and investigated as oxygen electrode for reversible solid oxide cells. The electrochemical performance of La0.6Sr0.4Fe0.8Ni0.2O3−δ oxygen electrode in fuel cell mode and electrolysis mode is investigated in detail. The maximum power density of 961 mW cm–2 and polarization resistance of 0.142 Ω cm2 at 800 °C can be achieved in fuel cell mode. While the cell is operated in electrolysis mode, the current density ranges from 0.53 A cm–2 at 750 °C to 1.09 A cm–2 at 850 °C with 50 vol % absolute humidity at 1.3 V, and the hydrogen generation rate can reach up to 1348.5 mL (cm2 h)−1 with 90 vol % absolute humidity at 800 °C. The reversible solid oxide cells show excellent reversibility and stability during 144 h medium-term reversible operation. The results indicate that La0.6Sr0.4Fe0.8Ni0.2O3−δ has a bright prospect as the oxygen electrode material for reversible solid oxide cells.