Quasi‐Antipolar Nanoclusters Driven Superior Energy Storage in High‐Entropy Relaxor Ferroelectrics

Relaxor ferroelectrics featuring highly dynamic polar nanoregions hold significant potential for pulse‐power dielectric capacitor applications. Nevertheless, achieving an optimal polarization‐field response that combines low hysteresis, delayed polarization saturation, and high maximum polarization remains a critical challenge toward superior comprehensive energy storage performance. Herein, we propose an effective strategy of engineering quasi‐antipolar nanoclusters in relaxor ferroelectrics via a high‐entropy composition design to optimize polarization behavior. By intentionally incorporating aliovalent ions with different ferroelectric activities into antiferroelectric NaNbO 3 , local antiparallel‐like polarization configurations were constructed within a high‐entropy relaxor matrix of Na 0.73 Ba 0.1 Bi 0.11 Li 0.06 Nb 0.73 Ti 0.22 Fe 0.05 O 3 (NBBLNTF). These quasi‐antipolar nanoclusters not only weaken the coupling among polar nanoregions but also exhibit distinct transition behaviors under high electric fields toward a ferroelectric state. Consequently, a polarization‐field loop with low hysteresis, high linearity, and large maximum polarization is achieved, yielding an ultrahigh recoverable energy density W rec of 18.3 J·cm −3 with a high efficiency η of 91.5% and an outstanding energy storage strength W rec /E of 0.25 J/(kV·mm −5 ) in NBBLNTF multilayer ceramic capacitors, together with excellent thermal and frequency stability. These results offer a feasible strategy for developing next‐generation high‐performance dielectrics with exceptional energy storage properties.