Strong relaxor enabling 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 (W_rec) and excellent charge/discharge performance in dielectric ceramics, remains a longstanding challenge. In this study, we report a high W_rec of 9.05 J cm⁻³ achieved in a straightforward binary lead-free relaxor system consisting of 0.9Bi_0.5Na_0.5TiO₃–0.1SmFeO₃. The improvement in energy storage performance is primarily attributed 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 for diminishing hysteresis and remnant polarization while simultaneously boosting relaxor characteristics, thereby enhancing overall energy storage density. Notably, the 0.9Bi_0.5Na_0.5TiO₃–0.1SmFeO₃ ceramics exhibit a high discharge energy density (W_dis) of 5.46 J cm⁻³ and a power density of 1470 MW L⁻¹ at 370 kV cm⁻¹, while also demonstrating excellent charge/discharge performance for practical applications. This research illustrates the potential for designing high-performance relaxor ferroelectrics using straightforward structural modifications.