From Nano to Macro: Multiscale Calculations of Thermal Transport in Graphene‐Skinned Cu Composites

Abstract Super graphene‐skinned (Gr‐skinned) materials are emerging members of the graphene composite family, which are synthesized through the high‐temperature chemical vapor deposition of continuous graphene on engineering materials, followed by ingenious postprocessing techniques. The continuous high‐performance graphene “skin” endows the engineering materials with excellent thermal conductivity. The Gr‐skinned Cu is taken as an example and conducted a multi‐scale study of their heat transfer mechanism by combining molecular dynamics with physical models. The results show that the heat transfer at the Cu/Gr interface is the rate‐limiting step within the Gr‐skinned Cu, where phonon heat transfer accounts for 86.59% and electrons contribute to 13.41%. This phonon‐electron synergistic effect enhances interfacial heat transfer. Compared to other Cu(hkl) surfaces, the Cu(111) surface has stronger interfacial phonon coupling with graphene, which is further enhanced by specific graphene defects, improving interfacial heat transport. Macroscopically, Gr‐skinned Cu foil and powder units can be composited into bulk to build up a well‐connected conductivity network. The thermal conductivity increment of Gr‐skinned Cu powder bulk is eight times that of Gr‐doped Cu composites with an identical number of graphene layers. This confirms the advantages of Gr‐skinned Cu in heat conduction, offering a novel strategy for optimizing graphene composites.