Enhanced breakdown strength and excellent energy storage stability by B site hetero-valent doping in Sr0.7Bi0.2TiO3-based lead-free ceramic

Abstract

Environment-friendly energy storage materials are embraced in global researches. Aiming at improving the energy storage performances of lead-free dielectric ceramics, the Sr0.7Bi0.2Ti(1–1.25x)NbxO3 (SBT-xN, x = 0 ∼ 0.125) lead-free ceramics were synthesized via the conventional solid state method in this work. Outstanding total energy storage density (Wtotal = 3.998 J/cm3), recoverable energy storage (Wrec = 3.43 J/cm3), and high energy storage efficiency (η of 85.84%) were obtained when x = 0.075 under the electric field of 385 kV/cm. Meanwhile, a satisfied temperature (30 ℃−110 ℃ variation less than 14%), frequency stability (10–400 Hz variation less than 1%), and anti-fatigue characteristic (107 cycles variation less than 1%) were achieved. Furthermore, the sample exhibited a remarkable discharge energy density (Wd = 3.885 J/cm3), ultrafast discharge speed (t0.9 = 73 ns), and giant discharge power density (Pd = 327.01 MW/cm3) at 400 kV/cm in charge-discharge tests. Great temperature stability (30 ℃−150 ℃ variation less than 8%) and pulse repetition frequency discharge stability (2×105 times variation less than 3.5%) were also obtained. The excellent characteristics suggest that the ceramic is a prospective candidate for advanced pulse power equipment.