Ultrahigh energy storage density, high efficiency and superior thermal stability in Bi0.5Na0.5TiO3-based relaxor ferroelectric ceramics via constructing multiphase structures

Abstract

Ceramic-based capacitors with high power density, fast charge/discharge rate and superior reliability are fundamental components for high/pulsed power devices. Bi_0.5Na_0.5TiO₃-based relaxor ferroelectric ceramics with a perovskite structure are among the up-and-coming candidates for capacitive energy storage because of their environment-friendly composition, easy-synthesis and high saturation polarization. However, the simultaneous achievement of ultrahigh recoverable energy density (W_rec), high energy storage efficiency (η) and superior reliability still remains a huge challenge because of the competition between various crucial parameters. Herein, multiphase structures with rhombohedral (R3c) and tetragonal (P4bm) phases are achieved in Bi_0.5Na_0.5TiO₃–Ba_0.7Sr_0.3Zr_0.8Sn_0.2O₃ ceramics. The coexistence of strong and weak coupled polar nanoregions (PNRs) results in a relatively high polarization (P_max) and a decreased remanent polarization (P_r). Accordingly, the selective ceramics display an ultrahigh W_rec of 7.4 J cm⁻³, a high η of 89% at 400 kV cm⁻¹ and remarkable thermal stability in a wide temperature range of 25–180 °C, exhibiting extraordinary comprehensive energy storage performances in BNT-based ceramic capacitors. This work demonstrates a feasible way for exploring high-performance dielectric capacitors.