An Active and Stable High‐Entropy Ruddlesden‐Popper Type La<sub>1.4</sub>Sr<sub>0.6</sub>Co<sub>0.2</sub>Fe<sub>0.2</sub>Ni<sub>0.2</sub>Mn<sub>0.2</sub>Cu<sub>0.2</sub>O<sub>4±δ</sub> Oxygen Electrode for Reversible Solid Oxide Cells
Xuelian Li, Ting Chen, Chenxiao Wang, Ning Sun, Guangjun Zhang, Yucun Zhou, Mian Wang, Jun Zhu, Lang Xu, Shaorong Wang
Abstract
Abstract Insufficient catalytic activity and stability of oxygen electrodes are major challenges for the widespread use of reversible solid oxide cells (Re‐SOCs). Here, a Ruddlesden‐Popper‐structured high‐entropy La 1.4 Sr 0.6 Co 0.2 Fe 0.2 Ni 0.2 Mn 0.2 Cu 0.2 O 4±δ (RP‐LSCFNMC) oxygen electrode with fast oxygen reduction and emission reaction kinetics, inhibited Sr segregation and favorable thermal expansion efficient is reported. A Re‐SOC with the RP‐LSCFNMC oxygen electrode achieves an encouraging peak power density of 1.74 W cm −2 in the fuel cell mode and a remarkable current density of 2.10 A cm −2 at 1.3 V in the water electrolysis mode at 800 °C. The Re‐SOC also shows excellent stability, with no Sr segregation observed after 120 h of testing in both the fuel cell and electrolysis modes at 750 °C. Furthermore, the improved activity and stability of the RP‐LSCFNMC oxygen electrode are confirmed through a combination of experiments and density functional theory‐based calculations. These findings make the high‐entropy RP‐LSCFNMC oxide a promising oxygen electrode candidate for advanced Re‐SOCs.