Improved dielectric breakdown strength and energy storage properties in Er2O3 modified Sr0.35Bi0.35K0.25TiO3

Abstract

The development of lead-free dielectric ceramics with excellent energy storage properties has received extensive research attention. Herein, Er2O3 modified Sr0.35Bi0.35K0.25TiO3 (SBKT) composite ceramic is investigated. As 2 wt.% Er2O3 is added, a certain amount of insulating second phase with fewer regions of high local electric field (numerically simulated by COMSOL) is formed, giving rise to the increase in the dielectric breakdown strength (BDS) due to the increased electrical resistivity and band gap, the decreased average grain size and the decreased leakage current density. This optimal composition exhibits many excellent energy storage properties, such as high energy storage density of 2.59 J/cm3, high recoverable energy storage density (Wrec) of 2.17 J/cm3 with high efficiency (η) of 83.9% at 245 kV/cm, superior stability of temperature (<1% variation of Wrec and η in −25 ~ 150 °C), frequency (~1.6% variation of Wrec with ~3.6% variation of η in 10 ~ 500 Hz) and cycling (almost no change of Wrec and η within 105 cycles), and high discharge energy density of 1.51 J/cm3 with high power density of 39.6 MW/cm3 at 200 kV/cm. In this work, we provide a novel strategy and understanding to design the advanced pulse energy storage ceramics.