Methylene Methanedisulfonate as an Electrolyte Additive for Improving the Cycling Performance of LiNi0.5Co0.2Mn0.3O2/Graphite Batteries at 4.4 V Charge Cutoff Voltage

Methylene methanedisulfonate (MMDS) is evaluated as a new electrolyte additive for improving the cycling performance of the LiNi0.5Co0.2Mn0.3O2/graphite cells cycled in the voltage range of 3.0–4.4 V. With the addition of 0.5 wt% MMDS in the electrolyte, the capacity retention of the cells increases from 70.7% to 94.1% after 100 cycles in 3.0–4.4 V, but has no difference in 3.0–4.2 V. The enhanced cycling performance of the cells with MMDS additive is ascribed to the surface modification of LiNi0.5Co0.2Mn0.3O2 cathode, which not only improves the conductivity of cathode electrolyte interface film but also suppresses the solvent decomposition at high voltage.