Enhanced high-temperature energy storage performance of PEI-based composite dielectrics via ultra-low content of SiC@SiO2 nanoparticles

Abstract

The advancement of organic/inorganic composite materials is essential for ensuring the reliable performance of polymer-based dielectrics in high-temperature electronic devices. In this paper, a core-shell structured filler, SiC@SiO₂, was prepared by coating a layer of SiO₂ on the surface of SiC using a simple high-temperature sintering method, which realized the synergistic enhancement of the breakdown field strength, dielectric constant and polarization response of the PEI matrix at 150 °C. The composite film prepared with the addition of 0.30 wt% SiC@SiO₂ displays a discharge energy density of 5.26 J cm⁻³ and maintained an efficiency of over 95 % at 150 °C and at the electric field of 500 MV/m. More importantly, we quantitatively characterized the interfacial thickness between the nanoparticle and PEI based on the Porod's theory by using SAXS, and analyzed the mechanism of the overall polarization response of the inorganic filler-enhanced composite films. In addition to determining the E_a and the E_g of the composite films, we also characterized the surface fractal dimension (D_s) and mass fractal dimension (D_m) according to the SAXS results, and systematically analyzed the mechanism of the core-shell packing to improve the breakdown strength. This work provides an effective modification strategy for optimizing the PEI-based composite films, and provides valuable theoretical insights into revealing the mechanism of energy storage performance at elevated temperature.