Selective Regulation of Cation Segregation in Perovskite: Interlayer High‑Entropy Design Toward Active and Durable Electrodes for Solid Oxide Cells

ABSTRACT The uncontrollable elemental segregation in perovskite materials at high temperatures leads to two critical challenges, the sluggish reaction dynamics and the poor stability of air electrodes, which severely impede the application of Solid oxide cells (SOCs). Here, an interlayer high‐entropy electrode (La 0.2 Pr 0.2 Nd 0.2 Sm 0.2 Gd 0.2 )Ba 0.5 Sr 0.5 Co 2 O 5+ δ (PBSC‐A) with a selective segregation function is designed through a high entropy synergistic effect. The high entropy successfully prevents the separation of alkaline‐earth metals, leading to enhanced stability of the electrode. The lattice distortion caused by high configuration entropy induces the Co segregation and oxygen vacancy generation, forming cobalt oxide nanoparticles decorated on the perovskite backbone, facilitating the kinetics of the electrode. An initial polarization impedance of only 0.11 Ω cm 2 is achieved, with no degradation over 200 h at 700°C. The PBSC‐A‐based cell demonstrates exceptional electrochemical performance, achieving a 41% increase in power density compared to the pristine cell at 700°C. The cell with PBSC‐A exhibits excellent stability in both fuel cell and electrolysis modes, with no significant degradation after 65 reversible cycles, highlighting its promise as an efficient bifunctional catalyst. Significantly, this work represents the first explanation and utilization of selective segregation in high entropy perovskite, providing a bright future for the development of active and robust electrodes.