High recoverable energy storage density in nominal (1-x)(0.75Bi0.5Na0.5TiO3-0.02BiFeO3-0.23BaTiO3)-xBi2SrNb2O9 lead-free composite ceramics

Abstract

Bi2SrNb2O9 with bismuth layer structure was added to Bi0.5Na0.5TiO3-BiFeO3-BaTiO3 ceramic with perovskite structure as an additive to improve its energy storage performance and temperature stability. A series of new lead-free energy storage ceramics (1-x)(0.75Bi0.5Na0.5Ti03-0.02BiFeO3-0.23BaTiO3)-xBi2SrNb2O9 (BNT-BF-BT-xBSN, x=0~0.025) were prepared by a traditional solid-state reaction method. The relaxation behavior and breakdown strength of BNT-BF-BT ceramics were improved, and remnant polarization was reduced after the addition of Bi2SrNb2O9, which originates from the formation of polar nanoregions (PNRs). Finally, the energy storage performance was improved. When x = 0.02, the recoverable energy density (Wrec) is as high as 4.2 J/cm3 under the low applied electric field of 160 kV/cm, the energy storage efficiency (η) of 85% was achieved. More importantly, the ceramic has excellent thermal stability (25-150 °C, ΔWrec/Wrec < 4%) and excellent fatigue durability (after 103 cycles, ΔWrec/Wrec < 10%). The charging and discharging performance of this material is also good, for example, a high power density of PD ~ 36.5 MW/cm3 and a fast discharge rate of t0.9 ~ 0.09 μs were obtained. These results indicate that BNT-BF-BT-0.02BSN ceramic is a promising material for dielectric energy storage application.

Keywords: Ceramics, energy storage, Bismuth layer structure, Polar nanoregions