High-entropy engineering for achieving linear-like behavior and superior energy storage in Bi0.5Na0.5TiO3-based lead-free relaxor ferroelectrics

Abstract

Dielectric capacitors are essential in modern power and electronic systems due to their ultrahigh power density and rapid charge–discharge capability. Nevertheless, their energy storage capacity is often constrained by pronounced hysteresis and nonlinear polarization behavior, which also limits progress toward device miniaturization. In this work, we present a high-entropy strategy to induce near-linear polarization behavior in Bi0.5Na0.5TiO3-based relaxors, resulting in markedly enhanced energy storage performance. The increase in configurational entropy is shown to break the long-range ferroelectric ordering, promoting the formation of nanoscale domains with weak coupling. This reduces the energy barrier for domain switching, thereby establishing a macroscopic linear-like polarization behavior. Multiscale characterization further indicates that such a weakly coupled domain structure not only enhances relaxor behavior and minimizes hysteresis but also enables high polarization under a highly applied electric field. Consequently, the optimized high-entropy ceramic achieves a remarkable recoverable energy density of 10.2 J cm−3 with an efficiency of 91.2% at 650.0 kV cm−1, together with outstanding stability across a broad temperature (20–180°C) and frequency (5–120 Hz) range, and a discharged energy density of 8.03 J cm−3. This study demonstrates a viable pathway for designing high-performance dielectric ceramics with near-linear polarization characteristics for advanced energy storage applications.