Patent attributes
Disclosed is a lithium secondary battery which is excellent in battery characteristics such as long-term cycle characteristics, capacity and shelf life characteristics. Also disclosed is a nonaqueous electrolyte solution which can be used for such a lithium secondary battery. Specifically disclosed is a nonaqueous electrolyte solution for lithium secondary batteries obtained by dissolving an electrolyte salt in a nonaqueous solvent which is characterized by containing 0.01-10% by weight of a carboxylate compound represented by the general formula (I) below and 0.01-10% by weight or 0.01-10% by volume of a vinylene carbonate and/or 1,3-propane sultone. Also disclosed is a lithium secondary battery using such a nonaqueous electrolyte solution. (In the formula, R2 represents a hydrogen atom or COOR3 group, R1 and R3 respectively represent an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group or a phenyl group, and X represents an alkynylene group or an alkenylene group.)
