Simultaneously achieving high energy storage density and efficiency under low electric field in BiFeO3-based lead-free relaxor ferroelectric ceramics

Abstract BiFeO3-BaTiO3-based relaxor ferroelectric ceramic has attracted increasing attention for energy storage applications. However, simultaneously achieving high recoverable energy storage density (Wrec) and efficiency (η) under low electric field has been a longstanding drawback for their practical applications. Herein, a novel relaxor ferroelectric material was designed by introducing (Sr0.7Bi0.2)TiO3 (SBT) into the composition 0.67BiFeO3-0.33BaTiO3 (BF-BT-xSBT). A large Wrec of ∼2.40 J/cm3 and a high η of ∼90.4 % were simultaneously realized under a low electric field of 180 kV/cm, which is superior to that of most previously reported lead-free ceramics. Moreover, moderate temperature endurance and excellent frequency stability were also obtained. More importantly, this ceramic has a large discharge current density (∼289.18 A/cm2), a discharge power density (∼14.46 MW/cm3) and short discharge time (