High‐temperature energy storage dielectric with inhibition of carrier injection/migration based on band structure regulation

Abstract Dielectric capacitors have a high power density, and are widely used in military and civilian life. The main problem lies in the serious deterioration of dielectric insulation performance at high temperatures. In this study, a polycarbonate (PC)‐based energy storage dielectric was designed with BN/SiO 2 heterojunctions on its surface. Based on this structural design, a synergistic suppression of the carrier injection and transport was achieved, significantly improving the insulating properties of the polymer film. In particular, the composite film achieves optimal high‐temperature energy‐storage properties. The composite film can withstand an electric field intensity of 760 MV m −1 at 100°C and obtain an energy storage density of 8.32 J cm −3 , while achieving a breakthrough energy storage performance even at 150°C (610 MV m −1 , 5.22 J cm −3 ). Through adjustment of the heterojunction structure, free adjustment of the insulation performance of the material can be realized; this is of great significance for the optimization of the material properties. image