Deferred Polarization Saturation Boosting Superior Energy-Storage Efficiency and Density Simultaneously under Moderate Electric Field in Relaxor Ferroelectrics

High-temperature dielectric Bi0.5Na0.5TiO3 (BNT)-based relaxors near a morphotropic phase boundary are developed with excellent energy storage performance. Random distribution of polar nanoregions induced by composition modulation would disrupt the ferroelectric long-range dipolar alignment and weaken the coupling between the ferroelectric domains, yielding slender and deferred polarization–electric field hysteresis loops with relatively high saturation polarization. The reversible nano-domain orientation and growth in relaxors under a delayed electric field result in negligible remnant polarization and advantageous energy storage properties. Simultaneously, superior recoverable energy storage density and efficiency are gained, significantly surpassing the state-of-the-art dielectric energy storage materials under similar moderate electric fields. Vacancies, defect dipole behavior, and structural evolution that relied on an electric field and temperature are discussed to disclose the underlying mechanism associated with phase transition. Even thermal stability and large electrostrictive strain with low hysteresis are achieved in elevated temperatures. These features demonstrate the promising candidates for dielectric energy-storage application and provide a strategy in designing relaxors.