Achieving ultrahigh energy storage performance in BiFeO3-BaTiO3 based lead free relaxors via a composition optimization strategy

The 0.63(1-x)Bi1.02FeO3-0.37BaTiO3-xBi(Zn2/3(Nb0.85Ta0.15)1/3)O3 (abbreviated BF-BT-xBZNT) high temperature dielectric ceramics were prepared via a two-step sintering (TTS) method. The appropriate medium permittivity achieved in the BF-BT-0.13BZNT ceramic is conducive to mitigating the polarization saturation and improving the breakdown field strength. The domain evolution behavior from piezoresponse force microscopy (PFM) reveals that the introduction of BZNT promotes the formation and switching of more nanodomains of BF-BT ceramics, facilitating the enhancement of energy storage efficiency. The excellent energy storage performance of total energy storage density (Wtot) of 6.06 J/cm3, recoverable energy storage density (Wrec) of 4.85 J/cm3 and a high energy storage efficiency (η) of 80% are simultaneously obtained under 410 kV/cm in the BF-BT-0.13BZNT ceramic. Meanwhile, the ceramic exhibits excellent thermal endurance (10–130 ℃), frequency (1–100 Hz) and fatigue (105 cycles) stability. The current work provides a promising strategy for designing high-performance dielectric energy storage materials which operate in harsh environments.