Thermodynamics and Kinetics of the Melt Crystallization of Fluoroethylene Carbonate

As one kind of important lithium-ion battery electrolyte, fluoroethylene carbonate (FEC) holds significant importance in improving battery performance. In response to the lack of research on the melt crystallization purification of FEC, thermogravimetric analysis (TG) and differential scanning calorimetry (DSC) were used to determine the thermodynamics and the nonisothermal crystallization kinetics of FEC. The binary solid–liquid phase equilibrium data for FEC-ethylene carbonate (EC) and FEC-vinylene carbonate (VC) systems were measured, calculated, and fitted by ideal solution, Van’t Hoff, Apelblat, λh models, non-random two-liquid (NRTL) model, and Wilson models. The results indicate that both FEC-EC and FEC-VC systems are eutectic mixtures, and the Apelblat model can give the best fitting results for the phase diagram data of both systems. The kinetics of the FEC melt crystallization process were also investigated. It was found that a faster cooling rate could result in higher supercooling.