Provided is an electrolyte solution for a lithium secondary battery and a lithium secondary battery having the same, the electrolyte solution further including an expressed solid salt which has an ammonium-based cation and a cyanide anion (CN−). According to an embodiment of the present invention, an electrolyte solution including the solid salt may be provided, and thus the problem of decrease in stability of a negative electrode due to copper ions that are dissolved from a copper current collector in a high-temperature environment may be resolved. Therefore, a lithium secondary battery having excellent battery performance such as battery capacity, charging and discharging efficiency, and cycle characteristics even under a high-temperature condition may be provided.