(Bi1/6Na1/6Ba1/6Sr1/6Ca1/6Pb1/6)TiO3-based high-entropy dielectric ceramics with ultrahigh recoverable energy density and high energy storage efficiency

Inspired by the development of high-power/pulsed-power techniques, dielectric capacitors with enormous power densities as well as ultrafast charge/discharge speeds have captured increasing attention and extensive research, particularly ceramic capacitors. Nevertheless, the limited recoverable energy density (Wrec) and/or low energy storage efficiency (η) of ceramic capacitors delay their applications in capacitive energy storage. Herein, single phase high-entropy (Bi1/6Na1/6Ba1/6Sr1/6Ca1/6Pb1/6)Ti1−xZrxO3 dielectric ceramics are designed and investigated. The enhanced dielectric relaxation behavior and fine grain size gave rise to decreased remnant polarization (Pr) and promoted electric breakdown strength (Eb). The special electronic structure of Pb2+ and Bi3+ favors retaining relatively large maximum polarization (Pmax). Accordingly, ultrahigh Wrec of 8.8 J cm−3, high η of 92.5%, and exceptional thermal reliability (Wrec = 4.5 J cm−3 ± 6.5% in the range of 25–180 °C) are synchronously achieved in the optimum composition of x = 0.12, providing a feasible strategy to explore high-performance dielectric ceramics for applications in electrostatic energy storage.