This study introduces a novel approach to achieve high energy-storage performance (ESP) in lead-free BNT-based ceramics under moderate electric fields. By meticulously regulating permittivity, enhancing insulation quality, and engineering domain structures through chemical formula optimization, the researchers achieved an ultrahigh energy-storage density of 7.19 J cm⁻³ and an outstanding storage efficiency of 93.8% at 460 kV cm⁻¹. The intricate structure-property relationship was elucidated using high-resolution transmission electron microscopy. The findings demonstrate that this approach effectively enhances ESP without compromising insulation or system downsizing, making BNT-based ceramics a promising candidate for pulse electrical devices.This study introduces a novel approach to achieve high energy-storage performance (ESP) in lead-free BNT-based ceramics under moderate electric fields. By meticulously regulating permittivity, enhancing insulation quality, and engineering domain structures through chemical formula optimization, the researchers achieved an ultrahigh energy-storage density of 7.19 J cm⁻³ and an outstanding storage efficiency of 93.8% at 460 kV cm⁻¹. The intricate structure-property relationship was elucidated using high-resolution transmission electron microscopy. The findings demonstrate that this approach effectively enhances ESP without compromising insulation or system downsizing, making BNT-based ceramics a promising candidate for pulse electrical devices.