Atomic-Scale High-Entropy Design for Superior Capacitive Energy Storage Performance in Lead-Free Ceramics.

Dielectric ceramics with high energy storage performance are crucial for the development of advanced high-power capacitors. However, achieving ultrahigh recoverable energy storage density and efficiency remains challenging, limiting the progress of leading-edge energy storage applications. In this study, (BiNa)TiO (BNT) is selected as the matrix, and the effects of different A-site elements on domain morphology, lattice polarization, and dielectric and ferroelectric properties are systematically investigated. Mg, La, Ca, and Sr are shown to enhance relaxation behavior by different magnitudes; hence, a high-entropy strategy for designing local polymorphic distortions is proposed. Based on atomic-scale investigations, a series of BNT-based high-entropy compositions are designed by introducing trace amounts of Mg and La to improve the electric breakdown strength and further disrupt the polar nanoscale regions (PNRs). A disordered polarization distribution and ultrasmall PNRs with a minimum size of ≈1 nm are detected in the high-entropy ceramics. Ultimately, a high recoverable energy density of 10.1 J cm and an efficiency of 90% are achieved for (CaSrBaMgLaBiNa)TiO. Furthermore, it displays a high-power density of 584 MW cm and an ultrashort discharge time of 27 ns. This work presents an effective approach for designing dielectric energy storage materials with superior comprehensive performance via a high-entropy strategy.