Bi_0.5Na_0.5TiO₃-based lead-free ceramics with superior energy storage properties at high temperatures

Dielectric capacitors with high energy storage and dielectric properties at high temperatures have significantly practical application in many fields. Lead-free ceramics of (1-x)(0.65Bi_0.5Na_0.5TiO₃-0.35Bi_0.2Sr_0.7TiO₃)-xBaSnO₃ were prepared by a solid-state reaction method. It was found that the 0.8(0.65Bi_0.5Na_0.5TiO₃-0.35Bi_0.2Sr_0.7TiO₃)-0.2BaSnO₃ ceramic shows a large recoverable energy storage density (W_r) of 3.75 J/cm³ and efficiency (η) of 84.8% under 380 kV/cm along with outstanding power density of 38.73 MW/cm³ under 130 kV/cm at room temperature. Additionally, a high W_r of 3.21 J/cm³ and η of 77% are achieved under a high electric field of 300 kV/cm at 100 °C. When the temperature reaches 140 °C, it still has a high W_r of 3.1 J/cm³ and η of 72%. The outstanding energy storage performance at high temperatures can be explained by the enhancement of breakdown strength and the constructing of polar phase stability caused by the introduction of BaSnO₃.