The role of graphene in Graphene-Filled carbon nanotube foam under compression and the corresponding microscopic deformation mechanism

Graphene-filling significantly improves the compressive properties of carbon nanotube (CNT) foam (CF). However, the role of graphene in the graphene-filled CNT foam (GFCF) and the corresponding microscopic deformation mechanism, are still unclear. Here, coarse-grained numerical models of pure CF and GFCF are constructed based on molecular dynamics, and the role of graphene in GFCF and corresponding microscopic deformation mechanisms under compression are investigated. It is found that the compressive modulus of GFCF (5.3 MPa) is much larger than that of pure CF (0.7 MPa). The filling of graphene inhibits the aggregation of CNTs, enhances the dispersion of CNTs, impedes the rearrangement of CNTs, and ultimately improves the compressive modulus of the whole material by improving the bending ability of CNTs. It is further found that the compressive modulus of GFCF can be increased to a maximum of 7.4 MPa as the number of graphene flakes increases to 300, but remains almost the same as the graphene thickness increases. The results in this paper deepen the understanding of the microscopic mechanisms of GFCF and provide scientific guidance for the application of CNT and graphene-based materials.