Tailoring the Reversible Phase Transition of Perovskite Nanofiber Electrodes for High-Performance and Durable Reversible Solid Oxide Cells

Abstract Reversible solid oxide cells (RSOCs) are capable of converting various energy resources, between electricity and chemical fuels, with high efficiency and flexibility, making them suitable for grid balancing and renewable energy consumption. However, the practical application of RSOCs is still limited by the insufficient activity and stability of the electrodes in different operating modes. Herein, a highly efficient symmetrical electrode composed of La 0.3 Sr 0.6 Ti 0.1 Co 0.2 Fe 0.7 O 3− δ (LSTCF) nanofibers and in situ exsolved Co 3 Fe 7 nanoparticles is developed for boosting the performance of RSOCs. The reversible phase transition, high activity and stability of the electrode have been confirmed by a combination of experimental (e.g., transmission electron microscopy and X-ray absorption fine structure) and computational studies. Electrolyte-supported RSOCs with the symmetrical electrode demonstrate excellent catalytic activity and stability, achieving a high peak power density of 0.98 W cm −2 in the fuel cell mode using H 2 as the fuel (or 0.53 W cm −2 using CH 4 as the fuel) and a high current density of 1.09 A cm −2 at 1.4 V in the CO 2 electrolysis mode (or 1.03 A cm −2 at 1.3 V for H 2 O electrolysis) at 800 °C while maintaining excellent durability for over 100 h.