Ultralow thermal contact resistance for graphene composite films enabled by liquid metal gallium microcapsules

Abstract

Liquid metals exhibit great potential in thermal management but suffer from leakage problems that seriously impact device safety and operation. To alleviate this issue, liquid metal microcapsules (LMMs) with gallium (Ga) as the core and silica as the shell are reported here. The Ga-microcapsules achieve significantly improved heat storage capacity (58.38 J g⁻¹) and high thermal durability (only 3.6% decrease in latent heat after 100 thermal cycles), attributed to the reduced supercooling by adding nucleating agents. By coating the microcapsules onto a graphene film, an LMMs/graphene composite film with high thermal performance is prepared, combining the high deformability of liquid metals with the high thermal conductivity of graphene. Compared to the bare graphene film, this composite film with 3.6 wt% microcapsules reduces the operating temperature of LED chips by 4.1 °C because of the largely reduced interfacial thermal resistance. Specifically, the thermal contact resistance between the thermal interface material and heater/heatsink decreases from 16.84 to 1.38 mm² K W⁻¹ under a pressure of 229 kPa, more than one order of magnitude lower than the commercial values. These results demonstrate the remarkable capability of LMMs in enhancing heat transfer, offering a promising approach for efficient heat dissipation in thermal management applications.