Local structure elucidation and properties prediction on KCl–CaCl2 molten salt: A deep potential molecular dynamics study

Abstract

KCl–CaCl 2 molten salt has emerged as a potential candidate which can be used for heat transfer and thermal energy storage in the next concentrating solar power generation. In this work, deep potential molecular dynamics (DPMD) simulations, based on a many-body potential and interatomic forces generated by a deep neural network trained with the first-principles simulation results, were carried out to predict the local structure and thermophysical properties of KCl–CaCl 2 molten salt at 1100 K. It was found that the steric hindrance effect became more and more intense as the network structure forming and growing with the addition of CaCl 2 , but the increase of CaCl 2 made the coordination shell of Ca 2+ more dynamic and active, and the two reactions constantly compete. Afterwards, thermophysical properties like shear viscosity, heat capacity and thermal conductivity were calculated from DPMD simulations. DPMD simulations could balance the proper description of complex atomic interactions to overcome the challenge of missing potential parameters in classical molecular simulations and become more efficient than first-principles molecular dynamics simulations. Our work based on deep potentials development will provide a promising alternative way to explore more molten eutectic salts for the next concentrating solar power generation. • Deep potential molecular dynamics simulations were carried out to explore the KCl–CaCl 2 molten salt. • Cl − ions more likely to be associated with Ca 2+ ions than K + ions in the KCl–CaCl 2 molten salt. • For KCl–CaCl 2 molten salt, heat capacity decreases with the addition of the CaCl 2 , shear viscosity and thermal conductivity increase slightly with the addition of the CaCl 2 .