(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 (W_rec) and/or low energy storage efficiency (η) of ceramic capacitors delay their applications in capacitive energy storage. Herein, single phase high-entropy (Bi_1/6Na_1/6Ba_1/6Sr_1/6Ca_1/6Pb_1/6)Ti_1?xZr_xO₃ dielectric ceramics are designed and investigated. The enhanced dielectric relaxation behavior and fine grain size gave rise to decreased remnant polarization (P_r) and promoted electric breakdown strength (E_b). The special electronic structure of Pb²⁺ and Bi³⁺ favors retaining relatively large maximum polarization (P_max). Accordingly, ultrahigh W_rec of 8.8 J cm^?3, high η of 92.5%, and exceptional thermal reliability (W_rec = 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.