Superior energy storage density and efficiency in antiferroelectric-like BNT-based ceramics via single-element phase engineering
Shuang He, Kunjie Lou, Bing Han, Shaobo Guo, Fei Cao, Chunhua Yao, Yizheng Bao, Genshui Wang
Abstract
Bi<sub>0.5</sub>Na<sub>0.5</sub>TiO<sub>3</sub> (BNT) has received much attention because of its excellent dielectric properties for pulsed power systems. Most of the work has focused on inducing the relaxation behavior of BNT-based materials by doping with multiple elements, but the preparation method is complicated because a high maximum polarization (<i>P</i><sub>max</sub>) is sacrificed, which affects the energy storage properties. In this work, we induced antiferroelectric-like relaxor behavior by replacing Bi<sup>3+</sup> with the single rare-earth ion Pr<sup>3+</sup> to obtain highly active polar nanoregions (PNRs) that increase the energy storage efficiency (<i>ƞ</i>). In addition, the 6s<sup>2</sup> lone pair of electrons of Pr<sup>3+</sup> can produce large ionic displacements similar to those of Bi<sup>3+</sup>. This could maintain the contribution of the A-site polarization to possess large <i>P</i><sub>max</sub>. Moreover, the high energy gap (<i>E</i><sub>g</sub>) and reliability increase the breakdown electric field (<i>E</i><sub>b</sub>). Consequently, the ultrahigh recoverable energy storage density (<i>W</i><sub>rec</sub>) of 11.01 J/cm<sup>3</sup> at 552 kV/cm and <i>η</i> of 86.7% are achieved with (Bi<sub>0.5−<i>x</i></sub>Pr<sub><i>x</i></sub>Na<sub>0.5</sub>)TiO<sub>3</sub> component (BPNT-18), which is superior to many other multielement components. It also has fast charging and discharging speeds (<i>t</i><sub>0.9</sub> ≈ 37 ns) and high power densities (<i>P</i><sub>D</sub> ≈ 312 MW/cm<sup>3</sup>). This research proposes a simple and effective approach in which a single element is used to obtain excellent energy storage performance in lead-free dielectric ceramics.