Highly Thermally Conductive Dielectric Nanocomposites with Synergistic Alignments of Graphene and Boron Nitride Nanosheets

Abstract

Electrically insulating polymer dielectrics with high energy densities and excellent thermal conductivities are showing tremendous potential for dielectric energy storage. However, the practical application of polymer dielectrics often requires mutually exclusive multifunctional properties such as high dielectric constants, high breakdown strengths, and high thermal conductivities. The rational assembly of 2D nanofillers of boron nitride nanosheets (BNNS) and reduced graphene oxide (rGO) into a wellaligned micro-sandwich structure in polyimide (PI) composites is reported. The alternating stacking of rGO and BNNS synergistically exploits the large difference in their electrical conductivities to yield a high dielectric constant with a moderate breakdown strength. Moreover, the distinctively separated rGO and BNNS layers give rise to higher thermal conductivities of composites than those containing mixed fillers because of reduced phonon scattering at the interfaces between two identical fillers, as verified by molecular dynamics simulations. Consequently, the micro-sandwich nanocomposite prevails over the PI film with a simultaneously high dielectric constant of ≈579, a high energy density (43-fold higher than PI) and an excellent thermal conductivity (11-fold higher than PI) at a low hybrid filler content of only 2.5 vol%. The multifunctional nanocomposites developed in this work are promising for flexible dielectrics with excellent heat dissipation.

Enhanced the Thermal Conductivity of Polydimethylsiloxane via a Three-Dimensional Hybrid Boron Nitride@Silver Nanowires Thermal Network Filler

“…The conduction network can be optimized by three-dimensional constructed structure. A higher thermal conductivity of composites can be obtained at a lower filling amount [ 27 , 28 , 29 ]. It was important to obtain high thermal conductivity under the condition of good mechanical properties and molding processing properties.…”

Three-dimensionally ordered macroporous BaTiO3 framework-reinforced polymer composites with improved dielectric properties

“…First, ceramic fillers with a high intrinsic dipole strength can enhance the effective dipole strength of polymer composites according to the effective medium theory [17]. Second, differences in dielectric constants or conductivities between matrix and fillers can induce Maxwell-Wagner-Sillars effect or equivalent microcapacitor effect [18][19][20].…”

Hydroxylated boron nitride materials: from structures to functional applications

“…HO-BNNS with large lateral size, around 2 lm, and a thickness of 4-14 nm has been produced by a three-step exfoliation strategy, involving a series of pretreatment-intercalation-exfoliation processes [77]. In short, pretreatment of h-BNs has been performed by using a mixture of H 2 SO 4 and HNO 3 and intercalation has been carried out by stirring in NaOH solution.…”