Nanocomposites with enhanced dielectric permittivity and breakdown strength by microstructure design of nanofillers

Abstract Polymer-ceramic nanocomposites play an essential role in pulsed power system, due to their ultrahigh power density and fast charging–discharging capability. They also hold strong potential for improving the performance in energy storage capacitors, hybrid electric vehicles and kinetic energy weapons, since they contain a high-breakdown-strength polymer matrix and high-dielectric-permittivity ceramic nanofillers and thus can reach a high level of energy-storage density. In this work, through a finite element method and a phase field model, we theoretically analyze the nanocomposites with enhanced dielectric permittivity and dielectric breakdown strength by microstructure design of ceramic nanofillers, which covers the orientation, morphology and arrangement of nanofillers. Results indicate that the orientation of ceramic nanofibers has significant influence on the dielectric permittivity and breakdown strength of nanocomposites. The comparison of nanoparticles and nanofibers reveals the increase extent of interactions between polymer matrix and ceramic nanofillers can enhance the dielectric breakdown strength of the nanocomposites. Based on the results above, two sandwich structures consisting of both nanoparticles and nanofibers have been constructed to pursue a higher energy storage density.