In the search for batteries for the next generation of energy storage systems, one of the most promising candidates for the next generation of energy storage and conversion devices is the Li–sulfur battery. Here, the lithium-metal anode is a critical component of the battery due to its low density and extremely high theoretical specific capacity. However, several challenges have prevented lithium anodes from becoming viable to be used in commercial batteries. Some of these issues are related to the continuous decomposition of the electrolyte when it is in contact with the Li surface, which leads to the formation of an inhomogeneous Solid-Electrolyte Interphase (SEI) layer. It has been suggested that a controlled SEI growth on the anode surface can enhance the performance of the battery. Therefore, a comprehensive understanding of how the electrolyte components react with the Li-metal may help us elucidate improvements in performance and provide some guidelines for enhanced materials to extend battery life. In this work, we use density functional theory (DFT) and ab initio molecular dynamics (AIMD) simulations to investigate the decomposition of a series of electrolyte mixtures including pure solvent (1, 2-dimethoxyethane - DME) and 1M solutions of LiFSI (Lithium bis(fluorosulfonyl)) or LiTFSI (Lithium bis(trifluoromethanesulfonyl)imide) in DME. From a rigorous analysis of the AIMD simulations, the reaction pathways, distribution of charge, and structure of the SEI are characterized in detail. In addition, in order to corroborate the decomposition mechanisms predicted from the dynamics, some insights on thermodynamics and kinetics of the reactions are presented.