Molecular Dynamics Simulation of the Effect of Zr, B, C, W, Ti, Hf, Nb, and Ta Elements on the K₃AlF₆-Na₃AlF₆-AlF₃ Molten Salt System

Abstract

The criticality of the physicochemical properties of the K3AlF6-Na3AlF6-AlF3 molten salt system to electrolytic aluminum production is a topic of great interest. In this study, molecular dynamics simulations were conducted to investigate the impact of Zr, B, C, W, Ti, Hf, Nb, and Ta on various properties including the radial distribution function, coordination number, viscosity, and conductivity of the 23.4K3AlF6-54.6Na3AlF6-22AlF3 molten salt electrolyte under conditions of 1173 K and standard atmospheric pressure. Significant and noteworthy discoveries were yielded by the simulations. A decrease in the coordination between Al-F and conductivity was brought about by the inclusion of B2-. Likewise, higher Zr4+ content resulted in a decrease in the coordination number between Al-F and viscosity. The impact of carbon was insignificant, while the presence of tungsten reduced the coordination number between Al-F. On the other hand, titanium, hafnium, niobium, and tantalum facilitated the decomposition of Al-F ligands, leading to an increased coordination between Al-F and the ions in the electrolyte. These findings provide valuable insights for future investigations on inert anodes containing Zr, B, Ti, Hf, Nb, and Ta. By understanding the effects of these elements on the physicochemical properties of the molten salt electrolyte, this work lays a solid foundation for further research in the field.