Achieved excellent energy storage performance under moderate electric field in BaTiO₃-modified Bi_0.5Na_0.5TiO₃-based lead-free ceramics via multiple synergistic design

Dielectric capacitors show great potential for use in pulse power devices due to their high power density. However, achieving ultrahigh recoverable energy density (W_rec) and efficiency (η) remains a challenge, limiting their applications. To address this, Na_0.5Bi_0.5TiO₃-BaTiO₃ (NBT-BT) ceramics were optimized for energy storage devices operating at a relatively low electric field (E). This study introduces a synergistic optimization strategy by incorporating Ca(Hf_0.7Zr_0.3)O₃ (CHZ) into 0.93NBT-0.07BT (BNBT) ceramics. The addition of CHZ, in concentrations ranging from x = 0.00 to 0.18, significantly enhances the differences between saturation and remnant polarization from 15.6 μC cm⁻² to 42.5 μC cm⁻², while reducing the grain size from 2.44 μm to 620 nm. An optimal W_rec of ∼5.09 J cm⁻³ with η of ∼77% was achieved in BNBT-0.14CHZ ceramics at a moderate electric field (283 kV cm⁻¹). Moreover, the energy storage density and efficiency exhibited good frequency stability (10-1000 Hz), temperature stability (25-150 °C) and fatigue resistance (1-10⁴ cycles). A fast discharge time (∼72 ns) was concurrently realized at x = 0.14 ceramics. These results suggest that the eco-friendly BNBT-0.14CHZ ceramic is a promising candidate for application in dielectric energy storage capacitors under moderate electric field.