Decomposition Mechanism of Ethylene Carbonate and Fluoroethylene Carbonate through Hydrogen Abstraction under High Voltage Environment: An Ab-Initio Study

Ab-initio molecular orbital calculations were done to propose a decomposition mechanism of an electrolyte under high voltage environment in lithium ion batteries. Ethylene carbonate (EC) and fluoroethylene carbonate (FEC) were examined as representative solvent molecules for a high voltage electrolyte. We especially focus on the decomposition paths of EC and FEC through H-deficient radicals. Although cationization of the radicals is possible under the operating potential of the cathode of the lithium ion batteries, the H-deficient radicals are more easily decomposed in the neutral charge state than that in the positive charge state. Present calculations show that FEC is relatively resistant to high voltage environment in comparison with EC in terms of the activation energy.