Molecular Dynamics Predictions of Thermal Conductivity in Graphene for Phase Change Energy Storage Applications

Additives of highly-conducting nanoparticles such as graphene to a phase change material (PCM) improves PCM heat diffusion, which in turn produces better energy storage than pure PCM. Equilibrium Molecular Dynamics (EMD) simulations with Green-Kubo relations are used to predict the thermal conductivity of graphene sheets of various sizes and using different ensemble formulations. The Tersoff potential function has been implemented to model the covalent bonds between carbon atoms. The MD simulations predict an increase in thermal conductivity with graphene sheet size, and the predictions for the canonical (NVT) ensemble are consistently larger than those using the microcanonical (NVE) ensemble. The autocorrelation functions for the NVT simulations converge to zero for large sampling periods, which is not the case for NVE simulations.