Facile Synthesis of a Graphene Film with Ultrahigh Thermal Conductivity via a Novel Pressure-Swing Hot-Pressing Method

A graphene film with high thermal conductivity and flexibility is highly demanded for heat dissipation application yet is still restricted by the complex and uneconomical fabrication process. Here, a facile and low-cost pressure-swing approach was adopted to realize the hot-pressing process of the graphene film. Accompanied by this pressure-swing hot-pressing process, the gas emission behavior was found to be crucial to the reduction of the graphene film. In this context, the applied pressure was adjusted to achieve the order and dense structure of the graphene film. The as-prepared graphene film thus presents a high thermal conductivity of 1451.37 W m^-1 K^-1 and a tensile strength of 175 MPa. Concomitantly, the heating rate was further retarded to slow the decomposition of functional groups on the graphene oxide film. The optimized graphene film exhibits a thermal conductivity of 1516.74 W m^-1 K^-1. Our results provide a highly promising method for preparing industrial-desired graphene films with high thermal conductivity.