Fabrication of sandwich-structured PPy/MoS2/PPy nanosheets for polymer composites with high dielectric constant, low loss and high breakdown strength

Polymer-based dielectric nanocomposites with high dielectric constant and low loss have been widely used for energy storage applications in power electronics and power delivery systems. However, there are still changes in preparing polymer-based dielectric nanocomposites with the suppressed loss (tan delta) and maintain breakdown strength (E-b) through simple compound method. In this work, a simple approach to fabricate outstanding comprehensive performance dielectric composites was proposed by cooperating molybdenum disulfide-polypyrrole (MoS2-PPy) hybrids with polyvinylidene Fluoride (PVDF). The MoS2-PPy hybrids were prepared by in situ polymerization of pyrrole with exfoliated MoS2 nanosheets, showing a "sandwich-like" structure of PPy/MoS2/PPy. MoS2-PPy hybrids significantly influenced the dielectric properties of their composites. As result, PVDF/MoS2-PPy composites achieved high dielectric constant (149.5@1 kHz), suppressed dielectric loss (0.19@1 kHz) and high breakdown strength (250.6 MV m(-1)). The emphasized reasons of high dielectric property are the enhanced interfacial polarization and formation of nano- and micro-capacitor networks. This work could provide an effective method to design and improve the performance of polymer-based dielectric nanocomposites for power system and energy storage applications.