Measurement and Correlation of Binary Systems Containing 1,2-Dichloroethylene Carbonate, Fluoroethylene Carbonate, and Ethylene Carbonate at 0.4 kPa

The surging demand for lithium-ion batteries (LIBs) in electric vehicles and energy storage drives the need for the efficient recovery of high-performance electrolyte additives, such as 1,2-dichloroethylene carbonate (DCEC), fluoroethylene carbonate (FEC), and ethylene carbonate (EC). Their high boiling points and thermal instability, including the risk of polymerization, pose challenges to recycling. This study reports experimental vapor–liquid equilibrium (VLE) data for DCEC + FEC, DCEC + EC, and FEC + EC binary systems at 0.4 kPa, measured using a recirculating still to enable low-temperature separation. The data, comprising the temperature, liquid-phase (x), and vapor-phase (y) compositions, were correlated with the NRTL, Wilson, and UNIQUAC models, with the NRTL showing a superior fit. Excess Gibbs energy (GE/RT) analysis indicated positive deviations for DCEC + FEC and negative deviations for DCEC + EC and FEC + EC, reflecting a system-specific nonideality. The thermodynamic consistency was verified using Van Ness and Wisniak’s L-W tests, confirming the data reliability. These novel VLE data and models fill a critical literature gap, providing essential thermodynamic insights for designing energy-efficient vacuum distillation processes to recover carbonate-based LIB additives and enhance the sustainability of battery manufacturing and recycling.