Fig. 2. The solvation structures and electrochemical performance.

a–c Schematic illustrations of solvation structure in three electrolytes. d Raman spectra of three electrolytes at 25 °C. e Molecular structure, HOMO, and LUMO energy levels for LiPF₆, LiFSI, EC, DMC, FEC, and MTFA. Energy levels for LiPF₆, LiFSI, EC, DMC, and FEC are referenced from Wang et al.⁶⁰ while that of MTFA was calculated by the same method. f–h Coulombic efficiencies of Li||Cu cells in three electrolytes under a current density of 0.5 mA cm⁻² for 1.0 mAh cm⁻² at different temperatures.