High-Temperature Energy Storage Dielectric with Double-Layer Deposition Structure

The lower energy density and decreasing insulation performance at high temperatures of energy storage polymer dielectric limit their application in military and civilian fields such as electromagnetic weapons and new energy vehicles. In order to further improve the breakdown strength and energy density at high temperatures, silica (SiO2) and boron nitride (BN) with wide band gaps were selected as the inorganic layers to in-situ grow and construct a double-layer barrier layer on the surface of polycarbonate (PC) films. The total deposition thickness with optimal performance was determined by adjusting the single-layer SiO2 thickness. Subsequently, BN was introduced to construct a heterojunction structure on this basis to further improve breakdown and energy storage performance. Achieving a higher energy density of 8.57 J/cm3 at 780 kV/mm and room temperature in PC composite dielectric, and an excellent energy density of 4.94 J/cm3 at 600 kV/mm and 150 ℃. The PC composite dielectric with heterojunction structures can effectively improve breakdown and energy storage performance by constructing an internal reverse electric field. This work provides more optimization pathways for research and development on high-temperature energy storage dielectric.