Excellent heat transfer and mechanical properties of graphite material with rolled-up graphene layers

The weak strength between the graphene layers and low cross-plane thermal conductivity (k) always restrict the application of graphite materials due to their lamellar structure. Inspired by the carbon nanotube, the graphene layers are rolled up to prepare a graphite bulk (the graphitized bulk) by the chemical vapor deposition (CVD) process in this work. With the rolled-up graphene layers, the cracks should grow in numerous graphene layers before the destruction of the graphitized bulk, which can effectively relieve the easy cleavage between the graphene layers, and the mechanical properties have improved significantly. Results show that the shear strength, elastic modulus and hardness of the graphitized bulk are about 15 times, 2.5 times and 5.5 times higher than that of the graphite material with the conventional structure (HOPG). Besides, this structure provides a 3D path for the heat to transfer, which effectively promotes the cross-plane k and α (about 3.7 and 5.9 times higher than that of HOPG). Infrared images and finite element simulation results reveal that the as-prepared graphite could show better heat transfer properties than HOPG.