Enhanced energy storage properties achieved in Na0.5Bi0.5TiO3-based ceramics via composition design and domain engineering

Dielectric ceramic materials with high power density and fast charge–discharge speed have attracted increasing attention in recent years. However, their mutually restricted energy density and efficiency as well as unsatisfactory temperature stability have been the main obstacles for their practical applications. Herein, a high recoverable energy density of 5.02 J·cm−3 and a high efficiency of ~ 90% can be obtained under 422 kV·cm−1 in the Sr0.85Sm0.1TiO3 (SST)-modified Na0.5Bi0.5TiO3 (NBT) ceramics via composition design and domain engineering strategy, and the excellent stability of energy storage properties in frequency (1–100 Hz) and temperature (20–180 °C) were also observed at 250 kV·cm−1 in the 0.50NBT-0.50SST ceramics, which are attributed to the improved breakdown strength (Eb) and the enhanced relaxation behavior. The increased band gap width and refined grain size are responsible for the significantly enhanced Eb of Na0.5Bi0.5TiO3-based solid solution, being confirmed by ultraviolet and visible (UV–vis) absorption spectra as well as scanning electron microscopy. The generation of polar nanoregions as demonstrated by piezoresponse force microscopy and transmission electron microscopy results in a negligible remanent polarization and thermally stable polarization-field response. It is worth noting that the energy density will be further greatly optimized due to the improvement of Eb if this ceramic composite is made into multilayer ceramic capacitor as a dielectric layer. Moreover, a large power density of 188.6 MW·cm−3 and a fast discharge speed of 70 ns can also be achieved in the optimized composition. The results show that the multi-scale optimization strategy is an effective way to realize excellent comprehensive energy storage performances in the Na0.5Bi0.5TiO3 based ceramics.