High Thermal Conductivity in Nano/Micro-Biphasic Liquid Metal/Carbon Nanofiber/Diamond Composite

Ga-based liquid metal (LM) composites incorporated with nanofillers hold substantial promise for application in the micro/submicron scale thermal management of electronic devices. However, the uniform compounding of LM with carbon nanofibers (CNFs) without phase separation is challenging. Herein, ultrasonic dispersion and in situ surface modification (phenolic resin, PR) were conducted to obtain a eutectic Ga–In (EGaIn)/CNF@PR compound. To further improve the low out-of-plane thermal conductivity of EGaIn/CNF, 27 wt % diamond microparticles were compounded with EGaIn/CNF containing 0.027 wt % CNF. A high thermal conductivity of 100 W m^–1 K^–1 was obtained, which was 384% higher than that of EGaIn. Combining the interfacial adsorption energy analysis, the bonding microstructure in the composite was CNF(/diamond)@PR@(Ga,In)₂O₃/EGaIn. Additionally, the composite exhibited excellent thermal performance as a thermal interface material in practical CPU tests. This indicates that combined use of micro and nano fillers can remarkably augment LM’s thermal conductivity at a relatively low filler content.