Bi0.5Na0.5TiO3-BaTiO3-K0.5Na0.5NbO3:ZnO relaxor ferroelectric composites with high breakdown electric field and large energy storage properties

0.82[0.94Bi0.5Na0.5TiO3-0.06BaTiO3]-0.18K0.5Na0.5NbO3:xZnO (BNT-BT-KNN:xZnO, x = 0-0.40) relaxor composites were prepared and their electrical properties were investigated. The breakdown electric field increases with increasing ZnO content. For x = 0 and x = 0.40 samples, the maximum recoverable energy storage density is 0.74 J/cm3 and 1.03 J/cm3 while the maximum energy storage efficiency is 86.7% and 72.7% under the electric field of 9.0 kV/mm and 14.0 kV/mm, respectively. The recoverable energy storage density and efficiency of the composite vary less than 2.5% from 25 °C to 125 °C, which indicates temperature-insensitive energy storage performance. These results are discussed based on the ZnO-enhanced bulk resistivity and the ZnO-induced local electric field which suppresses the evolution of polar nanoregions.