Li+ solvation in ethylene carbonate–propylene carbonate concentrated solutions: A comprehensive model

Spectroscopic (Raman, NMR, impedance spectroscopy), and thermal [differential scanning calorimetry (DSC)] techniques have been used to study the solvation mechanism of lithium ions in ethylene carbonate (EC)–propylene carbonate (PC) concentrated solutions. For values of N=[Li+]/[EC+PC]⩽0.2 all the cations are solvated by ∼4 solvent molecules and interaction chiefly takes place between Li+ and the ring oxygens. For N>0.2 a part of Li+ ions begins to form complexes with two solvent molecules (sandwich configuration). At N≅0.5 nearly all cations are complexed, and a crystalline compound is formed at room temperature. For higher values of N a reassociation of the salt takes place.