Harnessing Nanoscale Heterostructure Core–Shell Phase for Enhanced Energy Storage in BiFeO ₃ -Based Ceramics

Electrostatic capacitors are indispensable components in modern electronic and power systems due to their ultrafast charging/discharging capabilities and exceptional power density. However, their application is constrained by an inherently low energy density, hindering progress in device miniaturization and system integration. Herein, we propose a universal nanosized heterostructure core–shell phase design for BiFeO3-based ceramics to enhance energy storage capabilities. Atomic-scale structural analysis confirms the construction of a core–shell architecture comprising a rhombohedral (R) phase shell encapsulating a tetragonal (T) phase core. This distinctive structure could minimize hysteresis loss and delay polarization saturation by reducing polarization anisotropy and lowering domain-switching barriers while simultaneously improving breakdown strength through the introduction of disordered atomic configurations with localized lattice distortions and grain refinement. As a result, these features cause a high recoverable energy density of 10.5 J·cm–3. This study establishes a paradigm for high-performance dielectric capacitors, paving the way for advanced next-generation power devices.