Enhancing Bi-directional thermal conductivity: A novel tri-layer graphene-liquid metal composite for advanced thermal management

The rapid advancement of electronic devices demands the development of high-performance thermal conductive materials for efficient thermal management. This study presents a novel composite thermal conductive film featuring a unique sandwich structure designed to overcome critical challenges in thermal management. The composite is constructed using a graphene-carbon fiber matrix encapsulating liquid metal as the core layer, enclosed between graphene membranes. This design harnesses graphene's exceptional in-plane thermal conductivity, mechanical stability, and isolation properties; carbon fiber's structural support and lateral sealing; and liquid metal's superior thermal conductivity and gap-filling capabilities. The resulting film achieves outstanding thermal performance, with an in-plane thermal conductivity of 106.1 W/mK and a through-plane thermal conductivity of 43.1 W/mK. The sandwich structure effectively suppresses liquid metal leakage and corrosion under high-pressure conditions, while retaining robust mechanical integrity. Unlike common thermal interface materials, this three-layer structure performs distinct thermal management functions. The bottom layer, a graphene film, acts as a heat-spreading layer, transforming point conduction into faster surface conduction. The middle layer is a flexible vertical heat conduction layer, serving as a highway for heat transfer. The top layer efficiently dissipates heat due to graphene's excellent radiative properties. This composite material can thus be used not only as a thermal interface material but also as a heat dissipation material in small mobile electronic devices.