Abstract
Electrostatic dielectric capacitors with high power density are the fundamental energy storage components in advanced electronic and electric power systems. However, simultaneously achieving ultrahigh energy density and efficiency poses a persistent challenge, preventing the capacitive applications towards miniaturization and low-energy consumption. Here we demonstrate giant energy storage properties in lead-free antiferroelectrics by designing hierarchical heterostructures to optimize polarization evolution paths. Through the design of antiferroelectric nanoclusters featuring interlocked polarization structure and fishbone polarization configuration, alongside order-disorder oxygen octahedral tilts, we increase polarization fluctuation and delay polarization saturation with nearly eliminated hysteresis under ultrahigh external electric fields. Leveraging this strategy, we achieve an ultrahigh energy density of 21.0 J cm(-3) with an impressive efficiency of 90% in sodium niobate-based ceramics, underscoring the great potential of this methodology for designing high-performance dielectrics and other functional materials.