Achieving ultrahigh energy storage performance over a broad temperature range in (Bi_0.5Na_0.5)TiO₃-based eco-friendly relaxor ferroelectric ceramics via multiple engineering processes

The development of ABO₃ perovskite-structured dielectric materials with high recoverable energy storage density (W_rec) and power density (P_D) is crucial for the downsizing of pulsed power devices. Despite several research efforts, achieving a high W_rec over a wide working temperature range in an environmentally benign system remains a difficulty. A synergistic design strategy is given here, which includes concurrently doping at the A- and B-site to achieve a spread and depressed dielectric response, adding sintering aids, and employing advanced viscous polymer rolling technology for dense and ultra-thin ceramic samples, respectively. Finally, at a relatively low electric field of 380 kV/cm, an ultrahigh W_rec of 6.57 J/cm³ is realized in (Bi_0.5Na_0.5)_0.93Ca_0.07Ti_0.85Zr_0.15O₃-0.5 wt% Li₂CO₃ component, which benefits from gentle polarization saturating and improved breakdown strength. The W_rec can be maintained above 6 J/cm³ while maintaining strong thermal stability (variation ≤ ± 3%) over a temperature range of 30–150 °C. Because BNT-based materials have such high energy storage performance and temperature stability, they are not only a promising candidate for replacing lead-based dielectrics, but also a valuable guide for developing new high-performance ferroelectric materials for future energy storage devices in the pulsed power system.