Molecular Modelling of Lithium Salts in the Binary Mixtures of Ethylene and Ethyl Methyl Carbonates

Liquid electrolytes based on the organic solvents are the promising candidates for lithium-ion batteries. One of the most successful salt electrolyte systems are lithium hexafluorophosphate (LiPF6) and Lithium bis(trifluoromethanesulfonic) imide (LiTFSI) in ethylene carbonate/ethyl methyl carbonate (EC/EMC) mixture. Here we discuss ab initio molecular dynamics and classical molecular dynamics simulations of 1M and 3.5M of LiPF6 and 1M and 3.5M of LiTFSI salts in EC/EMC (11:25 v/v) systems. Particular attention is paid to the local structure organization at the atomistic level using the radial distributions between the constituents of electrolyte, as well as to their mutual coordination ability. The obtained results were confirmed by the comparison of the theoretically estimated structure factor with experimental small-angle X-ray scattering measurements. Commented on the effect of Li-ion solvation and hydrogen bonding interaction on the electrochemical properties of a Li-ion battery.