ELECTROLYTE FOR LITHIUM SECONDARY BATTERIES COMPRISING IONIC LIQUID AND COSOLVENT AND LITHIUM SECONDARY BATTERY COMPRISING THE SAME

An electrolyte for lithium secondary batteries includes an ionic liquid and cosolvents and a lithium secondary battery includes the same. The electrolyte includes a mixed solvent including the ionic liquid and the cosolvents, and at least one electrolyte salt, the cosolvents include a carbonate-based solvent and a nitrile-based solvent, and the mixed solvent includes 50-80 vol % of the ionic liquid, 15-45 vol % of the carbonate-based solvent, and 5-10 vol % of the nitrile-based solvent.