Near‐Zero‐Hysteresis Superparaelectrics Enabling Giant Energy Density With Ideal Efficiency in BaTiO ₃ ‐Based Multilayer Ceramic Capacitors

Ideal energy efficiency ( η ) with minimal energy loss is pivotal for the adoption of high‐energy‐density dielectric capacitors in sustainable technologies. In this work, guided by phase‐field simulation, we demonstrate a BaTiO 3 ‐based lead‐free ceramic featuring near‐zero polarization hysteresis under high electric fields. By implementing a high‐entropy composition design through synergistic co‐doping of multiple cations with varied valence states at A‐ and B‐sites, we induce a highly disordered superparaelectric state composed of heterogeneous, weakly interacting polar nanoclusters. Their fast, reversible reorientation under electric fields, attributed to substantial random fields, is directly visualized through in situ domain studies. The developed multilayer ceramic capacitor thus integrates a large recoverable energy density ( W rec ) of ~12.28 J cm −3 with an ideal efficiency ( η ) of ~ 98.08% and a superior figure of merit ( W F ) of ~ 640 under an electric field of 820 kV cm −1 , establishing it as a highly promising candidate for next‐generation pulsed power systems.