Improved energy storage performances in (1−x)Bi_0.5Na_0.5TiO₃–xSr_0.7Bi_0.2(Zn_1/3Nb_2/3)O₃ relaxor ferroelectrics

Lead-free dielectric ceramic capacitors (DCCs) characterized by wide operating temperatures and high recoverable energy storage density (W_rec) obtained under low electric fields (LEFs) have garnered significant attention in recent years. Herein, we have prepared (1 − x)Bi_0.5Na_0.5TiO₃–xSr_0.7Bi_0.2(Zn_1/3Nb_2/3)O₃ [abbreviated as (1 − x)BNT–xSBZN] ferroelectric ceramics using conventional solid-state sintering approach and have systematically studied the structural, dielectric, and energy storage performances (ESPs). The improved W_rec of 1.96 J/cm³ with a moderate storage efficiency (η) of 63% is obtained at x = 0.15 under a LEF of 145 kV/cm. The Raman spectra, dielectric constant curves, as well as P–E loops elucidate that the improved ESPs arise from the enhanced relaxation behavior, stemming from the local charge imbalance with lattice distortion caused by the introduction of SBZN. Meanwhile, the 0.85BNT–0.15SBZN ceramics demonstrate favorable stability within 25–180 °C. Additionally, a LEF of 140 kV/cm can lead to a high discharge density of 0.96 J/cm³. The experimental findings in this work suggest that 0.85BNT-0.15SBZN ceramics may be a promising option for energy storage DCCs, particularly at LEF conditions.