The influence of NaCl concentration on the (LiCl-KCl) eutectic system and temperature dependence of the ternary system

Abstract

To explore the complex correlation between local structure and properties in the alkali chlorides ternary system, simulations were systematically conducted for 11 different (Li, Na, K) Cl compositions from 900 K to 1200 K as the fundamental study of magnesium chloride electrolysis. For the ternary system, the density was calculated across the full composition and database was established. Furthermore, the structure simulation results revealed that the coordination of Li-Cl pair tended to be a distorted tetrahedron and the Na-Cl and K-Cl pairs tended to be an octahedron. The prediction of the properties was compared with available experiments and extrapolated analytical data, the deviations are acceptable. The temperature had no significant effects on the local structure and thermal conductivity. The results also showed that the Tosi−Fumi potential predicted positive temperature dependence of self-diffusion coefficients and ionic conductivity, and negative temperature dependence of the viscosity. In addition, the correlation between the local structure and transport properties was explored. The hydrodynamic radius of Li+ and K+ is similar in the ternary system, it can be found that whilst the K+ ion diffuses as an atomic species, the Li+ ion carries at least some of its coordinating Cl− ions in the diffusion process, giving the diffusing species a larger effective size than the bare ion.