Liquid electrolytes for electrochemical cells with silicon-based anodes are composed of an aprotic solvent, an ionic liquid, a lithium salt, and 8 mol % to 30 mol % hydrofluoroether. A molar ratio of the hydrofluoroether to the lithium salt is 0.22:1 to 0.83:1. The liquid electrolytes achieve at least a 50% improvement in cycle life over conventional electrolytes, extend capacity retention and delay increases in internal resistance.