Enhanced energy storage performance with excellent thermal stability of BNT-based ceramics via the multiphase engineering strategy for pulsed power capacitor

Abstract

High-temperature resistance and ultra-fast discharging of materials are among the hot topics in the development of pulsed power systems. It remains a significant challenge for dielectric materials to meet the requirements of storing more energy in high-temperature environments. In this work, lead-free (0.94 − x)(Bi_0.5Na_0.5)TiO₃–0.06BaTiO₃–xLa(Mg_2/3Ta_1/3)O₃ ceramics (x = 0.10–0.25) were synthesized via the solid-state reaction route, forming solid solutions through the coexistence of multiple phases. The highly dense microstructure optimizes the sample (x = 0.15) for a high energy-storage response, exhibiting an ultra-high energy storage density (W_s ∼ 10.80 J cm⁻³), recoverable energy density (W_rec ∼ 8.80 J cm⁻³) with efficiency (η ∼ 81.5%), and a high sensitivity factor (ξ = 205 J kV⁻¹ m⁻²) at an applied electric field (E_b ∼ 428 kV cm⁻¹). Additionally, this ceramic also shows a high-power density (P_D ∼ 210 MW cm⁻³) and ultra-fast discharge rate (t_0.9 ∼ 18 ns). The ultra-low variation of W_rec (ΔW_rec ≤ 1.3%) in the temperature range of 25–160 °C is also a remarkable feature of this ceramic. Moreover, the temperature coefficient of capacitance (TCC) for x = 0.15 is less than ±10% in the temperature range from −78 °C to 370 °C, which meets the X9R specification (ΔC/C_25°C ≤ ±15%, −55 to 200 °C) for capacitors. The high energy storage characteristics, high-power density, ultra-fast discharge rate, and excellent thermal stability reveal that the investigated ceramics have broad application prospects in pulsed power systems operating in high-temperature environments.