Solvation states and properties of binary mixtures of halogenated cyclic carbonates and a linear carbonate

The solvation states and properties of organic solvent electrolytes were investigated by 13C NMR measurements. The electrolytes were binary mixtures composed of halogenated cyclic carbonates such as chloroethylene carbonate (Cl-EC) or trifluoropropylene carbonate (TFPC) and a linear carbonate. Comparisons were made with the non-halogenated propylene carbonate (PC)/dimethyl carbonate (DMC) system. The solution structures of Cl-EC/DMC and TFPC/DMC systems, differing from those of PC/DMC system, have both cyclic and linear carbonates solvating to lithium ions. A study was also carried out on the performances of the model cells using organic electrolytes containing Cl-EC and TFPC as solvent, carbon anode, and lithium foil counter electrode. The current density dependence of the system using the pure TFPC as a solvent was much different from that of other systems. This is mainly due to the properties of interface between electrolyte and electrode of the cell.