Multiscale Structural Regulation of Energy Storage Properties and Their Mechanism of the (1 – x) (Bi_0.5Na_0.5)_0.7Sr_0.3TiO₃–xCa(Mg_1/3Ta_2/3)O₃ Ceramics

Ceramic dielectric capacitors have gained significant attention due to their ultrahigh power density, current density, and ultrafast charge–discharge speed. However, their potential applications have been limited by their relatively low energy storage density. Researchers have employed various approaches to enhance their energy storage density. In this study, (1 – x )(Bi 0.5 Na 0.5 ) 0.7 Sr 0.3 TiO 3 – x Ca(Mg 1/3 Ta 2/3 )O 3 ceramics were prepared via a solid-phase reaction, and the effect of their structure on the energy storage properties was investigated. The results indicate that the introduction of Ca(Mg 1/3 Ta 2/3 )O 3 significantly alters the multiscale structures of the (Bi 0.5 Na 0.5 ) 0.7 Sr 0.3 TiO 3 ceramic, including the transformation from the T -phase to the C -phase, refinement of ceramic grains, and the formation of polar nanoregions (PNRs), accompanied by an increase in the bandgap and relaxation degree. These structural changes collectively contributed to the improved overall energy storage properties of the modified ceramics. Notably, the 0.92(Bi 0.5 Na 0.5 ) 0.7 Sr 0.3 TiO 3 –0.08Ca(Mg 1/3 Ta 2/3 )O 3 ceramic demonstrated a recoverable energy storage density ( W rec ) of 8.37 J/cm 3 with an energy storage efficiency (η) of 87.7% at an electric field of 530 kV/cm. It also exhibited good temperature stability (25–120 °C), frequency stability (1–100 Hz), and fatigue stability (1–10 5 ). Furthermore, it displayed exceptional charge and discharge properties, with the discharge energy density ( W D ), discharge time ( t 0.9 ), current density ( C D ), and power density ( P D ) attaining 4.06 J/cm 3, 35.2 ns, 2143.28 A/cm 2, and 460.71 MW/cm 3, respectively. These findings suggest that modified (1 – x )(Bi 0.5 Na 0.5 ) 0.7 Sr 0.3 TiO 3 – x Ca(Mg 1/3 Ta 2/3 )O 3 ceramics are promising candidates for high-power pulsed electronic systems.