Thermodynamic Evaluation of Five Organic Carbonates and Their Mixtures Used in Lithium Ion Batteries

A thermodynamic database for 5 organic carbonates is compiled based on data from the literature. It includes the cyclic compounds ethylene carbonate (EC) and propylene carbonate (PC) as well as the linear carbonates dimethyl carbonate (DMC), diethyl carbonate (DEC), and ethyl methyl carbonate (EMC). For all of these substances the solid, liquid and gaseous phases are assessed. The solid phases are all treated as pure substances. In the liquid state, the cyclic compounds (EC+PC) form practically an ideal mixture which is also the case for the 3 binary combinations of the linear carbonates (DMC+DEC, DMC+EMC, DEC+EMC). The 6 binary liquids consisting of a linear and a cyclic carbonate exhibit all positive deviations from Raoult’s law. The gas phase is described by an ideal mixture of the 5 substances for temperatures up to 1000 K and pressures slightly above normal pressure. The Gibbs energy functions of all compounds are related to the SGTE data of pure elements (here C, H, and O) by adjusting the standard quantities of formation (Δ f H °, Δ f S °) to experimental data.