According to the computed reaction barriers, the Ce-Oe reaction mechanism is the preferred degradation pathway for the two solvent molecules resulting in the formation of carbonate species adsorbed at the surface and evolution of ethylene gas. In contrast, VC and FEC additive molecules favor the Cc-Oe degradation pathway due to significantly lower activation barrier. The Cc-Oe pathway favors the formation of CO gas molecules at the Li metal surface.