Moderate electric field driven ultrahigh energy density in BiFeO3-BaTiO3-based ceramics with improved relaxor behavior and breakdown strength

Dielectric ceramic-based capacitors have triggered growing concerns because of their potential applications in next-generation pulsed power electronic devices. However, the low energy density seriously hampers their further development, and the high energy density (>6 J/cm(3)) is generally realized under a giant external electric field (>500 kV/cm). Herein, an ultrahigh recoverable energy density of 8.5 J/cm(3) and a high efficiency of 87 % under a moderate electric field of 470 kV/cm is obtained in the Sr(Sc1/2Nb1/2)O-3 modified BiFeO3-BaTiO3 ceramics via the improved dielectric relaxation and electric breakdown strength (E-b). And the promoted band gap and reduced grain size play a key role in enhancing E-b. Moreover, the sample with the optimal composition also exhibits superb thermal reliability at a wide temperature range, and outstanding frequency and cycling stability under 350 kV/cm. This work not only provides a hopeful alternative for advanced energy storage capacitors, but also demonstrates an effective way to explore high-performance dielectric materials.