A non-aqueous electrolyte to be used in a Li-ion battery includes a lithium salt, a cyclic carbonate, a linear carbonate and an isocyanate-based additive, with the following general formula
R1—N═C═O
wherein R1 represents linear or branched alkyl groups which have 1 to 7 carbon atoms, or aromatic groups having the following general formula
wherein R2 and R3, which may be the same or different and located at any positions of carbons 2, 2′, 3, 3′ and 4 in the benzyl ring, represent hydrogen atoms or halogen atoms, isocyanate groups, either groups, ester groups or alkyl groups, having 1 to 3 carbon atoms, and are optionally substituted with halogen atoms.