Heteroepitaxial Barium Titanate/Niobium Potassium Oxide Polyimide Nanocomposite Films for High Temperature Energy Storage

Advanced electronic device components demand capacitors with high temperature resistance, high energy storage, and rapid charge and discharge speeds. The utilization of inorganic ceramics and organic polymer nanocomposite films in the field of high temperature energy storage holds the potential to attain this objective. Nevertheless, the primary challenge lies in the susceptibility of the composite film to breakdown under high temperature conditions. In this study, a barium titanate (BaTiO₃, BT)/niobium potassium oxide (KNbO₃, KN) complex with heteroepitaxial interfaces was prepared via the solvothermal method. Subsequently, BT/KN was filled in the polymerized polyimide (PI). Significantly, at the interface of BT and KN, p-n junction is formed. This unique structure effectively restricts the formation of conductive paths, and thereby significantly increases the breakdown field strength and energy density of the composite films. At 25 ℃ and 150 ℃, 5 wt% BT/KN/PI nanocomposite films attained energy densities of 5.45 J/cm³ and 4.69 J/cm³, corresponding to the breakdown field strength of 659.84 MV/m and 404.39 MV/m, respectively. Moreover, at 200℃, 3 wt% BT/KN/PI nanocomposite films exhibited an energy storage density of 2.18 J/cm³ at a breakdown field strength of 224.75 MV/m. This study demonstrates the significant potential of BT/KN/PI nanocomposite film capacitors for high temperature energy storage applications.