Li[Ni0.42Mn0.42Co0.16]O-2 (NMC442)/graphite pouch cells with 1 M LiPF6 in ethylene carbonate (EC): ethyl methyl carbonate (EMC) (3: 7 by weight) electrolyte containing 2 wt% vinylene carbonate (VC), 2 wt% prop-1-ene-1,3 sultone (PES), or 2 wt% PES + 1 wt% tris(trimethylsilyl) phosphite (TTSPi) + 1 wt% methylene methanedisulfonate (MMDS) ("PES-211") were subjected to cycling tests at various upper cut-off voltages from 4.2 to 4.7 V. After every 10 cycles, the pouch cells were charged or discharged to 3.8 V and evaluated using electrochemical impedance spectroscopy (EIS). This approach allows the impact of electrolyte additives on the impedance of cells cycled to different cut-off voltages to be studied systematically. The addition of 2% PES or "PES-211" proved to be beneficial in suppressing impedance growth when cells are cycled up to and above 4.4 V. Long-term cycling tests between 3.0 V and 4.4 V at 45 degrees C showed that "PES-211" had the best capacity retention (similar to 85%) and the least impedance growth after 500 cycles. The results suggest the use of "PES-211" could lead to longer lived and higher power NMC/graphite Li-ion cells with better tolerance to high voltage (4.4 V) which will improve energy density. (C) The Author(s) 2014. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited. All rights reserved.