Abstract: An electrolyte solution for a lithium secondary battery comprising a non-aqueous solvent, and an electrolyte and a carbonic ester derivative both dissolved therein, said carbonic ester derivative having the formula (I): ##STR1## wherein R.sup.1, R.sup.2 and R.sup.3 independently represent an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms, provided that R.sup.2 may be a hydrogen atom and provided that R.sup.1 and R.sup.2 may be connected through a methylene group to form a cycloalkyl group having 3 to 6 carbon atoms.

Abstract: A non-aqueous electrolyte lithium secondary battery comprising a cathode, an anode and a non-aqueous electrolyte comprising an electrolyte dissolved in a non-aqueous solvent, wherein the cathode is composed of a material containing a lithium complex oxide, the anode is composed of a material containing graphite and the non-aqueous solvent contains, as main components, a cyclic carbonate and a linear carbonate and 0.1 to 4% by weight, based upon the total weight of the non-aqueous solvent, of a sultone derivative having the general formula (I): ##STR1## wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5 and R.sup.6 independently represent an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms or a hydrogen atom and n is an integer of 0 to 2.