▎ 摘　　要

Although graphene-related nanocomposites have great potential for dissipating excess heat to ensure that electronic devices have high efficiencies and long service lives, their practical applications are restricted by the ultra-low through-plane thermal conductivity of these composites, which is due to interfacial thermal resistance between the graphene layers. Herein, exfoliated graphene (E-G)-boron nitride nanotube (E-G-BNNT) hierarchical structures are developedviathein situgrowth of BNNTs on E-G. The BNNTs play an essential role in the construction of vertically aligned "bridges" for connecting E-G nanosheets during the hot-pressing process, while covalent C-N bonding at the E-G and BNNT interface creates a heat transfer pathway between graphene layers to reduce interfacial thermal resistance. The resultant E-G-BNNT composite has an architecture that is close to an ideal thermal conductive filler, and it is highly efficient at improving the through-plane thermal conductivity of PDVF-based nanocomposites, reaching 3.12 W m(-1)K(-1)at a loading of 15 wt%. Non-equilibrium molecular dynamics (NEMD) simulations further show that the development of covalent C-N bonding between E-G and BNNTs can effectively boost the interfacial thermal conductivity. Such excellent heat conduction performance allows the nanocomposite to show great potential for thermal management.