关键词: 锂离子, 碳酸丙烯酯, N,N-二甲基甲酰胺, 优先溶剂化, ¹³C NMR

The preferential solvation of Li^＋ in propylene carbonate (PC) and N,N-dimethylformamide (DMF) mixed solvents has been studied by ¹³C NMR technique at various solvent and lithium salt concentration. The difference in the chemical shifts of the solvent with and without the electrolyte was attributed to the coordination of the solvent to Li^＋. Based on the observed dependence of the ¹³C NMR chemical shift for the solvents on the composition of the electrolyte, the coordinated atoms of the solvents to Li^＋ have been determined. The solvation ability of DMF to Li^＋ was found to be stronger than PC from the variation of coordination shift with the molar fraction of PC. It was shown that the molar ratio of PC to DMF molecules in the first solvation shell of Li^＋ was 0.12 in the ternary solution with equal mole of PC and DMF. These results indicated that Li^＋ was solvated preferentially by DMF molecules in the LiClO₄＋PC＋DMF mixtures.

Key words: lithium cation, propylene carbonate, N,N-dimethylformamide, preferential solvation, ¹³C NMR