Largely enhanced thermal conductivity of graphene/copper composites with highly aligned graphene network

Abstract Graphene has an ultra-high thermal conductivity (TC) along its basin plane. However, the TC of graphene/metal composites is still far below the expectation due primarily to the lack of sufficient graphene alignment in the metal matrix. Herein, we reported an efficient route to prepare the graphene nanoplatelet (GNP)/Cu composites with highly aligned GNPs by a vacuum filtration method followed by spark plasma sintering. Impressively, when the GNP fraction reached 35 vol%, a long-range and highly aligned GNP network was established within the Cu matrix, leading to a surprisingly high in-plane TC of 525 W/mK, which was 50% higher than that of Cu matrix and among the highest value ever reported for bulk graphene/metal composites. These results demonstrated that our strategy to construct a highly aligned graphene network could indeed achieve the remarkable in-plane TC enhancement in graphene/metal composites, and resulting composites may find application in electronic packaging that requires efficient directional heat transfer.