Excellent energy storage performance in Bi <sub>0.5</sub>Na <sub>0.5</sub>TiO <sub>3</sub>-based lead-free high-entropy relaxor ferroelectrics via B-site modification
Kaihua Yang, Gengguang Luo, Li Ma, Ruoxuan Che, Zhiyi Che, Feng Qin, Zhenyong Cen, Xiyong Chen, Jia-Jun Zhou, Nengneng Luo
Abstract
Next-generation advanced high/pulsed power capacitors urgently require dielectric materials with outstanding energy storage performance. The Bi<sub>0.5</sub>Na<sub>0.5</sub>TiO<sub>3</sub>-based lead-free material exhibit high polarization, but the high remanent polarization and large polarization hysteresis limit its application in dielectric capacitors. Herein, high-entropy perovskite relaxor ferroelectrics (Na<sub>0.2</sub>Bi<sub>0.2</sub>Ba<sub>0.2</sub>Sr<sub>0.2</sub>Ca<sub>0.2</sub>)(Ti<sub>1-<em>x</em>%</sub>Zr<em><sub>x</sub></em><sub>%</sub>)O<sub>3</sub> are designed by adding multiple ions in A-site and replacing the B-site Ti<sup>4+</sup> with a certain amount of Zr<sup>4+</sup>. The newly designed system showed high relaxor feature and slim <em>P</em>-<em>E</em> loops. Especially, improved relaxor feature and obviously delayed polarization saturation were found with the increasing of Zr<sup>4+</sup>. Of particular importance is that both high recoverable energy storage density of 6.6 J/cm<sup>3</sup> and energy efficiency of 93.5% were achieved under 550 kV/cm for the <em>x</em> = 6 ceramic, accompanying with excellent frequency stability, appreciable thermal stability and prosperous discharge property. This work not only provides a potential dielectric material for energy storage applications, but also offers an effective strategy to obtain dielectric ceramics with ultrahigh comprehensive energy storage performance to meet the demanding requirements of advanced energy storage applications.