Alkyl carbonate and gamma-butyrolactone (GBL) are attractive organic electrolyte materials that are stable over a wide range of operating voltages and ethylene sulfite (ES) is used as a supplementary film-forming electrolyte additive for lithium ion batteries (LIBs). This paper reports the solid-liquid phase equilibrium (SLE) data and the thermo-physical mixture properties such as the density, refractive index, excess and deviation properties for organic liquid electrolyte solutions of carbonate-based or GBL electrolytes containing ES. The SLE data were correlated with two activity coefficient models: NRTL and UNIQUAC. In addition, the extent to which the excess volume (V-E) and molar refraction deviation (Delta R) of each of the binary systems correlated with the values calculated using the Redlich-Kister polynomial equations was determined. (C) 2018 Elsevier B.V. All rights reserved.