Greatly enhanced discharge energy density and efficiency of novel relaxation ferroelectric BNT-BKT-based ceramics

The development of lead-free bulk ceramics with high recoverable energy density (W-rec) and high efficiency plays a major role in meeting the requirements for miniaturization and integration of advanced pulsed power capacitors. In this study, composition-dependent phase structures and ferroelectric properties of lead-free relaxor ferroelectric ceramics (1 - x)(0.84Bi(0.5)Na(0.5)TiO(3)-0.16K(0.5)Bi(0.5)TiO(3))-x(Bi0.2Sr0.7TiO3) [(1 - x)(BNT-KBT)-xSBT, x = 0-0.45] are investigated. The introduction of SBT into the morphotropic phase boundary (MPB) BNT-BKT system constructs the relaxor ferroelectrics according to the order-disorder theory, leading to an improved energy storage performance. Results show that an ultrahigh recoverable energy density of 4.06 J cm(-3) and a high energy-storage efficiency of 87.3% under an electric field of 350 kV cm(-1) are achieved concomitantly, together with a superior high temperature stability (30-160 degrees C) and strong fatigue endurance (10(4) cycles). In particular, the corresponding ceramic exhibits an ultrafast discharge rate (tau(0.9) = 127 ns) and a high level of discharge energy density (U-dis = 1.29 J cm(-3)). Our study provides the groundwork for an effective way to design high-performance ceramics for application in next generation energy storage capacitors.