Thermal transport properties of functionalized graphene/palmitic acid phase‐change composites: A molecular dynamics study

Abstract Considering the importance of high‐performance composite phase change materials (PCMs) for the realization of efficient thermal energy storage, molecular dynamics simulations were conducted in this study to investigate the thermal properties of graphene/palmitic acid composites and the related interfacial thermal transport. The effects of the interactions between functionalized graphene and fatty acids on the thermal transport properties needs to be investigated further. The addition of functionalized graphene (with epoxy, hydroxyl, and carboxyl groups) increased the phase transition temperature and decreased the specific heat capacity of the PCM, whereas both of these parameters increased with increasing functional group coverage (FGC). Further the effects of the FGC and functional group type on the interfacial thermal resistance (ITR) were investigated by analyzing the interaction energy and vibrational density of states, and the ITR decreased with increasing FGC. Compared to that of pure PA, the phase‐transition temperatures of the PA/pristine graphene composites were higher by ~7 K. The ability of functional groups to decrease the ITR decreased in the order of epoxy < hydroxyl < carboxyl at a constant FGC of 10.12%, with the ITR decreasing by 31.26%, 44.77%, and 56.41%, respectively. The obtained insights are expected to facilitate the design of high‐performance energy storage systems based on composites of fatty acids as PCMs. Highlights Thermal transport in functionalized graphene/palmitic acid composites is studied. Effects of functional group type/coverage on composite thermal properties are probed. Molecular dynamics simulations are used for thermal property analysis. The obtained insights promote the design of high‐performance phase‐change materials.