Atomically chemical heterogeneity endowing dielectric ceramics with ultrahigh energy storage

Harnessing local structural and chemical complexity in dielectric ceramics to reconcile large polarization, low hysteretic loss, and high breakdown strength is central to advancing dielectric capacitors for pulsed-power and high-voltage electronics. Here, we show that atomic-scale chemical heterogeneity, deliberately engineered in a relaxor ferroelectric perovskite matrix, provides an effective route to simultaneously elevate energy density and efficiency in bulk lead-free ceramics. Using canonical (Bi_0.5Na_0.5)TiO₃-based relaxor ferroelectric as a host, we propose an atomically chemical heterogeneity design by manipulating coupled A/B-sublattice occupancy correlations while preserving the average pseudocubic perovskite framework. Systematic characterizations of local chemical structures reveal nonrandom cation configurations at the atomic scale, severe local lattice distortion, and ultrafine slush-like multipolar nanodomains (1 to 4 nanometers in size) in which tetragonal, rhombohedral, orthorhombic, and nonpolar cubic regions coexist. This nanoscale polar landscape sustains a large electric field-induced polarization while strongly suppressing remanence and hysteresis, enabling an ultrahigh breakdown strength of 74.2 kilovolts per millimeter. As a result, the optimized ceramic delivers a recoverable energy density of 17.4 joules per cubic centimeter with 88% efficiency, together with excellent stability across different operation conditions. In particular, the fatigue endurance remains up to 10⁸ charge-discharge cycles under high electric fields. These results identify atomically chemical heterogeneity as a powerful and general design principle for high-reliability dielectric ceramics combining ultrahigh energy density with high efficiency.