Solvation of Mg2+ Ions in Mg(TFSI)2–Dimethoxyethane Electrolytes—A View from Molecular Dynamics Simulations

Abstract

Classical, polarizable molecular dynamics simulations have been performed for a series of Mg(N(SO2CF3)2)2–dimethoxyethane electrolytes with salt concentration varying in the range c = 0.1–1.2 M. It has been found that in dimethoxyethane solutions, magnesium salt exists as free ions, with metal cations coordinated to solvent molecules. Cation–solvent interactions favor TTT, TGT, and TGG′ conformations of dimethoxyethane, modifying the population of conformers in the electrolyte. Mg2+ ions form stable solvates with about three dimethoxyethane molecules. Two sets of solvent molecules with different mobility have been detected in simulations: fast diffusing free solvent molecules and dimethoxyethane molecules bound in the solvates, diffusing slowly with magnesium ions. All these findings are in good agreement with the recent experimental data.