Enhanced energy storage performance of Bi_0.5K_0.5TiO₃-based ceramics via composition modulation

To meet the booming demands for advanced pulse power systems, developing dielectric ceramics with excellent energy storage performance is extremely urgent. In this work, a composition modulation strategy was adopted for designing Bi_0.5K_0.5TiO₃-based ceramics. That is, incorporating Bi(Mg_0.5Hf_0.5)O₃ into 0.6Bi_0.5K_0.5TiO₃-0.4Sr_0.7Bi_0.2TiO₃ matrix (abbreviated as (1-x)(BKT-SBT)-xBMH, x = 0.00, 0.04 and 0.08). The energy storage performance of the (1-x)(BKT-SBT)-xBMH ceramics was enhanced by increasing the breakdown strength. Ultimately, a recoverable energy density (W_rec) of 4.25 J/cm³ together with an efficiency (η) of 87 % was achieved for the x = 0.04 ceramic at 360 kV/cm. Furthermore, excellent energy storage properties (W_rec ≥ 2.71 J/cm³, η ≥ 85 %) were obtained over a wide range of temperatures (20–200 ℃), frequencies (0.5–100 Hz) and cycle numbers (10⁵) under 260 kV/cm, indicating good thermal stability, frequency-independent character and fatigue-resistance behavior. Our work would open up a new avenue for preparing BKT-based dielectric ceramics.