Enhanced dielectric properties of epoxy-based multilayer composite with highly-controlled distribution of 2D nanomatierals

Abstract

Polymer-based dielectric materials are widely used in high-pulse electronic power systems to achieve energy storage and conversion. However, the miniaturization and high integration devices require for the advancement of polymer-based dielectrics with enhanced heat dissipation and energy density. Herein, sandwich-structured epoxy-based multilayer composite have been successfully achieved to explore the influence of morphological state of multiphase on thermal conductivity (TC) and dielectric properties. Dopamine-modified reduced graphene oxide (RGO@PDA) was introduced as 2D nanosheets to enhance the dielectric displacement, while, boron nitride nanosheets (BNNS) were incorporated to improve the TC and preserve low dielectric loss of epoxy-based dielectrics. In addition, poly(vinylidene fluoride) (PVDF) as outer layer was utilized to achieve high dielectric constant simultaneously. The resultant sandwich-structured PVEP-1.5 composite (with the central epoxy/polyetherimide (EP/PEI) layer and the outer PVDF layers) possessed an optimized high dielectric constant ε’ of 24.1 and exhibited a maximum TC of 1.22 W·m⁻¹K⁻¹. The ε’ was 6 times higher than EP/PEI single layer and 2.4 times higher than PVDF single layer, and the TC enhancement efficiency was up to 330 %. The breakdown strength (E_b) and energy storage density (U_e) of PVEP-1.5 reached 176 kV·mm⁻¹ and 1.5 J·cm⁻³, respectively, representing a remarkable improvement over the pristine EP/PEI (E_b = 47.3 kV·mm⁻¹ and U_e = 0.044 J·cm⁻³). The synergetic effect of multiphase morphology and the selective distribution 2D nanosheets presented great potential for the fabrication of epoxy-based multilayer composites with enhanced energy storage performance and superior heat dissipation property.