Strong relaxor enabled excellent capacitive energy storage performance in Bi0.5Na0.5TiO3-based binary system

Abstract

Dielectric ceramics have attracted significant interest in power electronic systems owing to their high-power density and rapid charge/discharge capabilities. However, achieving excellent capacitive energy storage performance, including high recoverable energy density (Wrec) and excellent charge/discharge performance in dielectric ceramics remains a longstanding challenge. In this study, we reported a high Wrec of 9.05 J/cm3 achieved in a straightforward binary lead-free relaxor system consisting of 0.9Bi0.5Na0.5TiO3–0.1SmFeO3. The improvement in energy storage performance is attributed primarily to two factors: (Ι) the introduction of Sm3+ intensifies relaxor activity in the matrix, which helps delay polarization saturation; (ΙΙ) the addition of Fe3+ not only disturbs the polar order within certain Ti4+ sites but also enlarges the local structural cell volume, providing more space for ion movement. Together, these mechanisms are crucial in diminishing hysteresis and residual polarization while simultaneously boosting relaxor characteristics, thereby enhancing overall energy storage density. Notably, the 0.9Bi0.5Na0.5TiO3–0.1SmFeO3 ceramics exhibit a high discharge energy density (Wdis) of 5.46 J/cm3 and a power density of 1470 MW/L at 370 kV/cm, while also demonstrating excellent charge/discharge performance for practical applications. This research illustrates the potential for designing high-performance relaxor materials using straightforward structural modifications.