Significant improvement of energy storage density and efficiency of 0.72Bi0.5Na0.5TiO3-0.28SrTiO3 ceramics and study of the mechanism of high temperature energy storage performance

The energy storage properties of the 0.72Bi0.5Na0.5TiO3-0.28SrTiO3 system have been heavily investigated; however, achieving both high recoverable energy storage density (Wr) and large energy efficiency (η) remains a challenge. In this study, relaxor ferroelectric ceramics exhibiting high Wr and η were prepared by introducing BaSnO3 into 0.9(Bi0.5Na0.5)0.72Sr0.28TiO3-0.1Bi(Mg0.5Ti0.5)O3 relaxor ceramics. A remarkable Wr of 7.5 J/cm3 and η of 91.2% were achieved in the 0.94[0.9(Bi0.5Na0.5)0.72Sr0.28TiO3-0.1Bi(Mg0.5Ti0.5)O3]-0.06BaSnO3 ceramic at an electric field of 460 kV/cm. The η and the energy storage potential (Wr/Eb), respectively, surpass those reported for most ceramics in recent years. The introduction of high-temperature-stable BaSnO3 imparted excellent temperature and frequency stability to the ceramic. The ceramic exhibited a Wr of 3.6 J/cm3 and an η of 79.6% at 160 °C and 265 kV/cm. The sample has a power density of 202.8 MW/cm3, an energy density of 2.2 J/cm3 at an electric field of 260 kV/cm, and a fast charge–discharge capability.