Coupled Reconstruction of Local Polarization and Octahedral Tilting Enables Ultrahigh Dielectric Energy Storage

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 NaNbO₃-based ceramics, characterized by randomly distributed dipole-glass nanodomains embedded within a nonpolar matrix, together with highly disordered and weakly antipolar BO₆ 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 NaNbO₃-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.