Enhancing energy storage performances of Bi0.5Na0.5TiO3-based dielectric ceramics via modulating polymorphic polar nanoregions

Abstract

Relaxor ferroelectrics are primary candidates for high-performance energy storage dielectric capacitors. For the practical application of capacitors, high energy storage density and high efficiency (η) are both required, the pursuit of which remains challenging. Herein, a novel 0.88Bi_0.47Na_0.47Ba_0.06TiO₃-0.12Sr(Ni_1/3Nb_2/3)O₃ (12SNN) lead-free ceramic is proposed to enhance the energy storage properties by modulating highly dynamic polymorphic polar nanoregions (PNRs). The introduction of SNN leads to the formation of PNRs with high flexibility, regulates the ratio of rhombohedral and tetragonal PNRs, avoids polarization saturation at an electric field far below the breakdown field, and suppresses the energy loss. As a result, a high recoverable energy density (W_rec) of 7.0 J cm⁻³ and a high η of 81.5% are achieved simultaneously. Additionally, the superior performance is maintained across a wide range of temperatures (25–120 °C) and frequencies (1–500 Hz). Our findings indicate that the novel 12SNN ceramic shows excellent overall energy storage performance and provides a feasible method for exploring high-temperature applications in capacitors.