High capacitive performance at moderate operating field in (Bi0.5Na0.5) TiO3-based dielectric ceramics via synergistic effect of site engineering strategy

Despite a great deal of research efforts on the search for high recoverable energy storage density (Wrec) at high breakdown strength, high voltage operating security and high cost of associated insulation technology are the major barriers to limiting the actual applications of advanced pulse power capacitors, and thus have increased the requirement on the electrostatic energy storage at finite electric field level. Herein, we propose an effective strategy on tailoring energy storage performance under moderate driving field via the synergistic effect of site engineering in (Bi0.5Na0.5)TiO3-based ceramics. Based on extensive experimental researches, a large Wrec (2.78-3.46 J/cm(3)) and a high efficiency (80-90%) under moderate electric field (<250 kV/cm) have been synchronously attainted in the optimized relaxor ferroelectric ceramics, generating a high energy storage coefficient that exceeds most previously reported dielectric bulk ceramics. Besides, the optimized ceramic possesses good thermal stability (25-200 degrees C), strong fatigue endurance (after 2 *10(5) cycles) and outstanding frequency stability (1-500 Hz). More importantly, high discharge density of 1.15 J/cm(3), large power density of 65.6 MW/cm(3), and ultra-short discharge time of 72 ns with excellent fatigue endurance are also simultaneously achieved. This contribution not only develops a practical lead-free candidate material for electrostatic energy storage, but also offers a feasible approach to design high-efficiency lead-free dielectrics for low electric field high-energy storage applications using synergistic effect of site engineering.