LiFSI/DMTMSA Electrolyte Suppresses Stress-Corrosion of 4.7Volt NMC Cathodes and Enables Practical Li Batteries

An electrochemical device includes a transition metal oxide cathode, such as LiNi0.8Co0.1Mn0.1O2, and an electrolyte. The electrolyte includes N, N-dimethyltrifluoromethane-sulfonamide (DMTMSA) and lithium bis(fluorosulfonyl)imide (LiFSI). The DMTMSA and LiFSI may be either the primary component of the electrolyte or an additive in the electrolyte. The electrochemical device may also include a graphite anode or a lithium metal anode. With a lithium metal anode, the electrochemical device has an initial specific capacity of at least 231 mAh g−1. Over at least 100 cycles (upper cut-off voltage of 4.7±0.05 V vs. Li/Li+), the electrochemical device maintains an average specific capacity of at least 88% of the initial specific capacity and an average Coulombic efficiency of at least about 99.65%.