Ultrahigh energy-storage dielectric ceramics via synergistic polymorphic nanodomain and defect design

Dielectric capacitors are critical for advanced energy storage due to their ultrahigh power density and rapid charge-discharge rates. However, their application is limited by the low energy density. Here, we design a BaTiO3-(K0.5Na0.5)NbO3-(Bi0.5Na0.5)Ti0.9Zr0.1O3 solid-solution system through synergistic polymorphic nanodomain engineering and defect optimization. By engineering polymorphic nanodomains with coexisting rhombohedral, orthorhombic, tetragonal, cubic nanodomain in 1.0–2.0 nm size and defect design with reduces oxygen vacancy concentration and forms defect complexes, we achieve an ultrahigh energy density of 18.7 J cm⁻3 with remarkable efficiency of 92.1% in multilayer ceramic capacitors, along with excellent cycling stability (>107 cycles) and thermal stability (<±5% from 25 to 150 °C). In this work, we provide a paradigm for designing high-performance dielectric capacitors through the synergistic manipulation of domain structures and defect engineering. Authors designed BaTiO3-based multilayer ceramic capacitors through synergistic polymorphic nanodomain and defect optimization, achieving 18.7 J cm-3 and 92.1% efficiency with excellent stability, offering a paradigm for synergistic domain and defect engineering.