The consumption via reductive and oxidative decompositions of vinylene carbonate (VC) molecules as an electrolyte additive at the anode and cathode in a 18650 lithium-ion battery was quantitatively analyzed with charge-discharge tests, NMR spectroscopy, and gas chromatography. It was unambiguously concluded that the molar number of VC reductively decomposed at the anode has the upper limit whereas that of VC oxidatively decomposed at the cathode depended highly upon the initial VC concentration. The excess amount of VC molecules causes the increase in oxidative decomposition at the cathode surface eventually reducing the Columbic efficiency at the first cycle. (C) The Author(s) 2016. Published by ECS. All rights reserved.