Zi Wang, Weichen Zhao, Zhaochen Xi, Wenyuan Liu, Li He, Diming Xu, Guoqiang He, Yang Liu, Guiwei Yan, Xin Wang, Jian Bao, Zhen Fang, Xu Liang, Takahiro Shimada, C. Liu, Tao Xu, Wenfeng Liu, Tao Zhou, Dong Wang, Di Zhou
ABSTRACT Dielectric capacitors are an indispensable component in modern electronic power systems. However, achieving high recoverable energy density ( W rec ), high efficiency ( η ), and excellent temperature stability simultaneously remains a significant challenge, limiting the practical application of advanced technologies. Here, guided by phase‐field simulations, we propose a dipole glass state strategy in NaNbO 3 ‐based ceramics, characterized by randomly distributed dipole‐glass nanodomains embedded within a nonpolar matrix, together with highly disordered and weakly antipolar BO 6 octahedral tilting. The approach can effectively reduce hysteresis losses and enhance breakdown electric field by decreasing domain size and refining grain, yielding an ultra‐high W rec of 15.1 J·cm −3 and a high η of 90.5%, which represents a breakthrough in NaNbO 3 ‐based ceramics with η greater than 90%. This work establishes a mechanism‐driven design principle for advancing next‐generation high‐performance dielectric energy‐storage materials.