Insights into CaCl2-NaCl-KCl molten salt: A machine learning approach to unraveling structure and properties

The CaCl₂-NaCl-KCl molten salt exhibits unique advantages in cost, performance, and environmental impact, making it an exceptionally attractive option for Concentrated Solar Power (CSP) systems. This study focuses on investigating the microstructure and physicochemical properties of CaCl₂-NaCl-KCl molten salt at varying CaCl₂ concentrations using the machine learning (ML) potential. The strength of chloride ions and cation interactions is Ca²⁺ > Na⁺ > K⁺. The geometries of the first coordination shells surrounding Ca²⁺, Na⁺, and K⁺ ions with Cl⁻ are all distorted octahedral structures, and this distortion is more severe with increasing CaCl₂ content. As more CaCl₂ is present in the system, the structure becomes more compact due to the transition from a low coordination structure to high coordination structure. In addition, the simulated density, self-diffusion coefficient, shear viscosity and electrical conductivity were obtained under different CaCl₂ molar fraction. The exploration of diverse composition in CaCl₂-NaCl-KCl molten salt holds the potential to advance the design and execution of CSP systems, fostering enhanced efficiency, cost-effectiveness, and environmental sustainability. Furthermore, it can contribute to the scientific understanding of CaCl₂-NaCl-KCl molten salt as a heat transfer and energy storage medium.