Multi-scale enhanced energy storage performance in Sm(Mg0.5Sn0.5)O3-modified Bi0.47Na0.47Ba0.06TiO3 ceramics with a composite structure

Abstract

Lead-free dielectric capacitors have attracted widespread attention for their high power density, ultra-fast charge–discharge rate and excellent chemical stability. Nevertheless, low energy storage density (W_rec < 9 J cm⁻³) and energy storage efficiency (η < 85%) limit their further development. The 0.80(Bi_0.47Na_0.47Ba_0.06TiO₃)-0.20Sm(Mg_0.5Sn_0.5)O₃ ceramics achieved excellent comprehensive energy storage performance (W_rec ∼ 9.91 J cm⁻³, η ∼ 87.01%) and stability over a wide temperature range (25–200 °C) at 700 kV cm⁻¹. The introduction of Sm(Mg_0.5Sn_0.5)O₃ (SMS) constructs a local random field, and the large-size ferroelectric macrodomains are decomposed into high dynamic polar nanodomains (PNRs), which effectively suppresses the generation of early polarization saturation and achieves high ΔP (∼31.92 μC cm⁻²). Interestingly, SMS-modified Bi_0.47Na_0.47Ba_0.06TiO₃ ceramics have a 0–3 type composite structure consisting of a pyrochlore phase Sm₂Sn₂O₇ and a main phase. The low dielectric constant of the secondary phase and the refined grains increase the breakdown field strength (E_b). Due to the stable local structure and improved relaxation properties, the ceramics exhibit excellent temperature stability (W_rec and η are maintained at 2.62 ± 0.06 J cm⁻³ and 87.03 ± 2.96% at 25–200 °C, respectively). This work provides a theoretical basis for the future development and design of high energy storage materials.