Molecular Dynamics Simulation of the Concentration Effect on the Structure and Physicochemical Properties of Lithium Perchlorate Solutions in Sulfolane

Molecular dynamics simulation of LiClO 4 solutions in sulfolane has been performed in a wide range of concentrations from 2 × 10 2 to 7 × 10 3 mol/m 3 (7 M) using the Opslaa force field. It was found that the total coordination number (the sum of coordination numbers for sulfolane and perchlorate anion) of the lithium cation decreased with an increase in the lithium perchlorate concentration in solution from 5.7 to 4.5. It was shown that sulfolane solvates one lithium cation by one oxygen atom regardless of the salt concentration; but above the salt concentration 2 × 10 3 mol/m 3 (2 M) (molar ratio of sulfolane/LiClO 4 < 5), sulfolane acts as a bridging ligand between two lithium cations; the lithium perchlorate anion is coordinated with the lithium cation by one oxygen atom; only at the molar ratio sulfolane/LiClO 4 = 1 (salt concentration 7 × 10 3 mol/m 3 ) the perchlorate anion acts as a bridging ligand and is coordinated with several lithium cations at once. At a concentration of 2.35 × 10 3 mol/m 3 (sulfolane/LiClO 4 = 4), the structure of the first solvation shell of the lithium cation changes; the perchlorate anion is introduced in it, filling the vacancies in the coordination sphere that appear because of the lack of free sulfolane molecules.