LiCoO2/graphite pouch cells with 1 M LiPF6 in EC:DEC (1:2 v/v) (control electrolyte) containing selected additives and different amounts of intentionally added water were studied. Archimedes principle was used to track gas evolution while an automated storage system, electrochemical impedance spectroscopy and cell cycling experiments were used to study electrochemical properties imparted by the addition of water. Water was added from 125 to 2000 ppm to control electrolyte and to electrolyte with 2% vinylene carbonate (VC) and/or 2% lithium bis(trifluoro methane sulfonyl imide (LiTFSI). The addition of water to either VC or VC + LiTFSI-containing electrolyte resulted in minimal or no changes in voltage drop and charge transfer resistance during storage while both added water and LiTFSI actually decreased swelling during storage. Added water to control electrolyte or VC-containing electrolyte did not impair cell cycling performance at 55 degrees C. Solution nuclear magnetic resonance (SNMR), in-situ gas measurements, gas chromatography coupled with a thermal conductivity detector (GC-TCD), and X-ray photoelectron spectroscopy (XPS) were employed to understand why added water did not affect cell performance. (C) The Author(s) 2016. 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.