Improved breakdown strengths and energy storage properties of polyimide composites: The effect of internal interfaces of C/SiO2 hybrid nanoparticles

Abstract

AbstractPolymer nanocomposites with high energy‐storage capability have been widely used in electronic devices. To achieve further enhanced energy density, developing nanofillers with tailored compositions and nanostructures is demonstrated to be an effective strategy. Especially, hybrid nanoparticles (NPs) with abundant internal interfaces are acknowledged as a promising candidate. Here, a class of carbon/silica hybrid nanoparticles (C/SiO2 h‐NPs) with disorderly mixed nanostructures are synthesized and employed to prepare C/SiO2 h‐NPs/polyimide nanocomposites. To reveal the influence of internal interfaces on dielectric properties, a series of comparative composites co‐filled with C and SiO2 NPs are also prepared. The breakdown strength of the C/SiO2 h‐NPs/polyimide composites can reach 303.96 kV/mm, which is over 200% that of their counterparts. It is believed that the abundant heterogeneous interfaces inside the C/SiO2 h‐NPs can effectively impede the development of conductive paths, thereby obviously enhancing breakdown strengths. Furthermore, the C/SiO2 h‐NPs/polyimide composite with 5 wt% C/SiO2 h‐NPs demonstrates a high discharged energy density of ~0.612 J/cm3 at 150 kV/mm, which is about 2.29 times higher than pure polyimide (PI) (~0.267 @ 150 kV/mm), along with a high discharge energy efficiency of 85.9%. This work offers a practicable strategy for the design of functional NPs toward high‐performance dielectric composites.