Greatly enhanced discharged energy density and efficiency of BiFeO3-Based ceramics by regulating insulation performance

Abstract

BiFeO3 (BFO) with excellent intrinsic polarization (Ps > 100 μC/cm2) receives a great deal of attention for advanced lead-free ferroelectric materials. However, the low resistance and high leakage current density in its naturally seriously hinder the improvement of energy storage performances. Herein, we demonstrate that superb comprehensive performances of large discharged energy density (Wrec ∼ 6 J/cm3) along with superior discharged efficiency (η ∼ 90%), impressive frequency stability (1–500 Hz), fatigue resistance testing (1-105 cycles) and ultrafast discharged time (t0.9–0.08 μs) could be attained in 0.3BiFeO3-0.7(0.88BaTiO3-0.12Bi(Li1/3Hf2/3)O3 [BFO-(BT-BLH)] relaxor ferroelectric ceramics. Remarkably improved breakdown strength (Eb) of BFO-based solid solutions could be primarily contributed to the substitution of BT-BLH, which provides refined grain sizes, as well as increased bandgap, resistivity, and activation energy. The phase-field simulations further indicate that the refined grain sizes are beneficial to improving local electric field distribution and breakdown path, resulting in enhanced Eb. The uncovered BFO-based ceramics design method provides a platform for high-performance capacitors development for extreme conditions.