Fluorinated Carbonate-Based Electrolyte for High-Voltage Li(Ni0.5Mn0.3Co0.2)O-2/Graphite Lithium-Ion Battery

Abstract

A stable electrolyte system at a charge voltage over 4.5 V is the key to successfully obtaining higher energy density by raising the charging cutoff voltage. We demonstrate a fluorinated electrolyte (1 M LiPF6 fluoroethylene carbonate (FEC) and methyl (2,2,2-trifluoroethyl) carbonate (FEMC) (FEC/FEMC = 1/9, v/v)) for a high-voltage LiNi0.5Mn0.3Co0.2O2/graphite system. The stability of the fluorinated electrolyte for the LiNi0.5Mn0.3Co0.2O2 (NMC532) cathode was investigated using scanning electron microscopy, X-ray photoelectron spectroscopy, and electrochemical impedance spectroscopy. The charge-discharge performance of the fluorinated electrolyte was superior to the corresponding non-fluorinated electrolyte system at a charging cutoff voltage of 4.7 V. (C) The Author(s) 2017. Published by ECS. All rights reserved.