Compromise Optimized Superior Energy Storage Performance in Lead‐Free Antiferroelectrics by Antiferroelectricity Modulation and Nanodomain Engineering

Abstract Lead‐free antiferroelectrics with excellent energy storage performance can become the core components of the next‐generation advanced pulse power capacitors. However, the low energy storage efficiency caused by the hysteresis of antiferroelectric‐ferroelectric transition largely limits their development toward miniaturization, lightweight, and integration. In this work, an ultrahigh recoverable energy storage density of ≈11.4 J cm −3 with a high efficiency of ≈80% can be realized in La‐modified Ag 0.5 Na 0.5 NbO 3 antiferroelectric ceramics at an ultrahigh breakdown electric field of ≈67 kV mm −1 by the compromise optimization between antiferroelectricity enhancement and nanodomain engineering, resulting in the transformation of large‐size ferrielectric antipolar stripe domains into ultrasmall antiferroelectric nanodomains or polarization nanoregions revealing as Moiré fringe structures. In addition, the enhanced transparency with increasing La content can also be clearly observed. This work not only develops new lead‐free antiferroelectric energy storage materials with high application potential but also demonstrates that the strategy of compromise optimization between antiferroelectricity modulation and nanodomain engineering is an effective avenue to enhance the energy storage performance of antiferroelectrics.