Achieved excellent energy storage performance under moderate electric field in BaTiO3-modified Bi0.5Na0.5TiO3-based lead-free ceramics via multiple synergistic design†

Abstract

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.