| 摘要 |
Provided are an electrolyte solution for a lithium secondary battery which is excellent in ion dissociation, ion conductivity and thermal stability, and a lithium secondary battery containing the electrolyte solution which is improved in thermal stability without the deterioration of physical properties. The electrolyte solution comprises a lithium salt comprising LiPF6 and LiBF4 in a molar ratio of 5-95 : 95-5; and a nonaqueous organic solvent. Preferably the nonaqueous organic solvent is at least one selected from the group consisting of a liner ester and a cyclic ester. Preferably the linear ester is at least one selected from the group consisting of dimethyl carbonate, ethylmethyl carbonate, diethyl carbonate, dipropyl carbonate, dibutyl carbonate, methyl acetate, ethyl acetate, methyl hexanoate and methyl formate; and the cyclic ester is at least one selected from the group consisting of ethylene carbonate, propylene carbonate, butylene carbonate, gamma-butyrolactone, gamma-valerolactone, gamma-caprolactone, delta -valerolactone and epsilon-caprolactone. Preferably the electrolyte solution comprises further an internal pressure improver; and/or a salt selected from the group consisting of LiClO4, LiAsF6, LiCF3SO3, Li(CF3SO2)2N and LiC4F9SO3. |
