Bi0·5Na0·5TiO3–Sr0.85Bi0·1TiO3 ceramics with high energy storage properties and extremely fast discharge speed via regulating relaxation temperature

Abstract

Bi0·5Na0·5TiO3-based relaxor ferroelectric ceramics have recently gained increasing attention due to their outstanding energy storage properties. However, the trade-off between the recoverable energy storage density/efficiency and discharge rate resulted from the hysteresis of domain switching process, severely limits their applications. Herein, a strategy realizing synergistic excellent energy storage properties and fast discharge rate is proposed through regulating relaxation temperature. The relaxation temperature was decreased to below room temperature by introducing Sr0·85Bi0·1TiO3 into Bi0·5Na0·5TiO3 [(1-x)Bi0·5Na0·5TiO3-xSr0.85Bi0·1TiO3, x = 0.5–0.7)], enabling the small size and weak correlation polar nanoregions (PNRs) with relatively high polarization. The trade-off was overcome by reducing the hysteresis of electrical switching of weak correlation PNRs. Thus, large recoverable energy storage density of 2.32 J/cm3 and high efficiency of 80.1% (250 kV/cm) were achieved simultaneously for x = 0.7 ceramics. Meanwhile, extremely rapid discharge rate (<30 ns) and remarkable power density of 63.7 MW/cm3, which were superior to the previously reported lead-free ceramics were realized. Besides, the 0.3BNT-0.7SBT ceramics also possess good thermal stability over 25 °C–115 °C at 100 kV/cm and good frequency stability (5–100 Hz). These properties make the 0.3BNT-0.7SBT ceramic an ideal candidate for energy storage applications.