Non-aqueous electrolyte and lithium secondary battery using the same

A lithium secondary battery, comprising:

• an electrolyte assembly comprising a cathode, an anode, and a separator interposed therebetween;
• and
• a non-aqueous electrolyte solution consisting of an electrolyte salt, an organic solvent, a sulfur-containing compound, and pyrimidine,
• wherein the organic solvent consists of a non-fluorinated solvent and a fluorinated solvent, wherein the amount of fluorine (F) present in the organic solvent is in the range of 0.9 to 45.2 wt %,
• wherein the non-fluorinated solvent includes a mixture of cyclic carbonate and an ester,
• wherein the ester is selected from the group consisting of methyl propionate, ethyl propionate, and a mixture thereof,
• wherein the cyclic carbonate is selected from the group consisting of ethylene carbonate, propylene carbonate, and mixtures thereof,
• wherein the fluorinated solvent includes fluoroethylene carbonate and optionally at least one selected from the group consisting of 2-(trifluoromethyl)-3-ethoxydodecafluorohexane, ethyl heptafluorobutyrate, and mixtures thereof,
• wherein the sulfur-containing compound is 1,3 propane sultone,
• wherein the sulfur-containing compound is present in an amount of 0.5 to 3 parts by weight based on 100 parts of the organic solvent, wherein the anode comprises a carbon-based material as an active material;
• and
• a polymerizable film present on a surface of the anode, wherein the polymerizable film is formed by a reaction of the pyrimidine with the anode,
• wherein the pyrimidine is present in an amount of 0.5 to 3 parts by weight based on 100 parts of the organic solvent prior to formation of the polymerizable film.