Enhanced energy storage properties in BNST-based lead-free relaxor ferroelectric ceramics achieved via a high-entropy strategy

The 0.65(Bi_0.5Na_0.5)TiO₃–0.35SrTiO₃-based materials are essential for the development of pulse power capacitors. However, their low recoverable energy storage density and breakdown field strength have hindered further improvement. To address this, a high-entropy strategy based on multiscale regulation is proposed, which involves synergistically manipulating the activation energy and microstructure evolution in BNST-based ceramics through the introduction of Ba(Zr_0.2Ti_0.2Sn_0.2Hf_0.2Ta_0.2)O₃. The inclusion of high-insulating oxides can significantly raise the activation energy of the entire system. Furthermore, the high-entropy material can significantly increase the atomic disorder and lattice distortion, resulting in strong local polar fluctuations on several nanoscales and excellent energy storage characteristics. As a result, this approach yields an impressive W_rec of ∼ 4.89 J/cm³ and a high efficiency of ∼92.1 % at 351 kV/cm, and the outstanding thermal endurance (20∼150 °C), frequency stability (5∼1000 Hz) and fatigue (10⁰∼10⁵ cycles). This study provides an effective strategy for achieving excellent comprehensive performances in high-entropy ceramics.