Fabrication of robust and highly thermally conductive nanofibrillated cellulose/graphite nanoplatelets composite papers

In this work, a lightweight and flexible composite paper has been successfully fabricated by incorporating nanofibrillated cellulose (NFC) with graphite nanoplatelets (GNPs). The NFC, with a high tensile strength but a low thermal conductivity, forms interconnected networks existing in the interspace of GNPs, which can significantly improve the tensile strength of the as fabricated composite paper. Interestingly, with the presence of NFC, graphite nanoplatelets are well aligned within the composite, thus forming effective thermal transport paths along the in-plane direction. Benefiting from the reinforcement and guiding effect derived from the incorporation of NFC, the composite paper exhibits considerably enhanced tensile strength while maintaining its high thermal conductivity. Specifically, the hybrid film with 75 wt % GNPs shows an in-plane and through-plane thermal conductivity of 59.46 W m−1 K−1 and 0.64 W m−1 K−1, respectively, with a satisfactory tensile strength of 46.39 MPa, thereby exhibiting great potential as an appropriate choice for lateral heat dissipation applications. Our findings provide a promising candidate, manufactured by a facile and low-cost process at industrial scale, for lateral heat dissipation applications.