Advance of molecular dynamics simulations in the thermophysical properties of molten salts: a critical review

Molecular dynamics (MD) simulations are widely used to investigate the thermophysical properties and microstructure of materials. This review comprehensively summarizes MD simulations of molten salts and nanoparticle-enhanced composites, emphasizing the calculation methods of key thermophysical parameters, including density, viscosity, thermal conductivity, specific heat capacity, radial distribution function (RDF), mean square displacement (MSD), and self-diffusion coefficient, performed using the widely adopted software such as LAMMPS and Materials Studio. It reveals that, through these computational approaches, how the effects of nanoparticles on the thermophysical properties of molten salts at the microscopic scale would be like. Nanoparticles can enhance thermal conductivity by altering ion collision frequency and forming an interfacial compression layer; while the existence of interfacial thermal resistance has a certain impact on the overall thermal conductivity of composite materials. In addition, RDF analyses show that the addition of nanoparticles leads to an increase in local ordering of ion distribution in molten salts, thereby increasing the specific heat capacity and phase transition temperature of the material. The calculations of MSD and self-diffusion coefficients indicate that the addition of nanoparticles significantly restricts ion diffusion, thereby improving the heat transfer performance of molten salt system. The present researches lack an understanding of the synergistic mechanisms between different nanoparticles in multicomponent composite systems. Combining multiscale simulation methods with experimental data and incorporating machine learning in MD simulations to improve accuracy and reliability are future directions, which would further enhance the efficiency of molten salt phase change materials in high-temperature energy storage applications.