Measurement and Correlation of the Binary Systems Containing Vinylene Carbonate, Fluoroethylene Carbonate, and Chloroethylene Carbonate at 0.4 kPa

Abstract

The rapid growth of lithium-ion battery technology, driven by the demand for electric vehicles and energy storage solutions, has intensified the need for high-performance electrolyte additives such as vinylene carbonate (VC), fluoroethylene carbonate (FEC), and chloroethylene carbonate (CEC). However, recovering these compounds is challenging because of their high boiling points and the polymerization tendency of the vinyl groups at elevated temperatures. Herein, the vapor–liquid equilibrium (VLE) data (T, x_i, and y_i) of binary systems containing VC, FEC, and CEC were determined to avoid inter/intramolecular polymerization using recirculation still at 0.4 kPa. The experimental data were then correlated and predicted using the nonrandom two-liquid (NRTL), Wilson, and UNIQUAC models, revealing a close agreement between the experimental and model-calculated data. The Gibbs free energy (G^E/RT) calculations showed positive deviations from the ideal behavior for the VC + FEC and VC + CEC binary systems, whereas the FEC + CEC system exhibited negative deviations, with the maximum excess Gibbs free energy observed near equimolar concentrations. A thermodynamic consistency test confirmed the reliability of the data. This research provides essential thermodynamic data for the recycling processes of lithium-ion battery additives, addressing a critical gap in the literature.