Excellent energy storage performance of polyetherimide filled by oriented nanofibers with optimized diameters

Abstract

Polymer-based dielectric composites have become a research topic in recent years owing to their excellent breakdown strength and power density. However, the long-standing challenge associated with energy storage research is that energy storage efficiency and energy storage density cannot often be obtained together. In this study, the diameter and orientation distribution of one-dimensional BaTiO3 nanofibers (BT NFs) were controlled, and the BT NFs were covered with an appropriate thickness of SiO2 buffer layer to form a core-shell structure. It is worth noting that when the diameter of BT NFs is about 500 nm (BT-2), the polyetherimide (PEI)-based composite BT-2@SiO2/PEI with a filling volume of 0.5 vol% has excellent energy storage performance. Specifically, the composite has an impressive Weibull distribution breakdown strength (Eb) of 629 kV/mm, excellent energy storage efficiency (η) of 86.1%, and outstanding discharge energy density (Ue) of 15.4 J/cm3. The experimental and simulation results show that the diameter of the nanofibers affects the distribution of the electric field in the composites. In addition, the excellent energy storage performance is associated to the oriented nanofibers and reasonable electric field distribution in the composite. This work not only perfects the research based on PEI energy storage system but also opens a new door for the selection and optimization of polymer-based dielectric nanocomposite.