Non-aqueous electrolyte solutions comprising additives and non-aqueous electrolyte cells comprising the same

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

wherein R¹ represents linear or branched alkyl groups which have 1 to 7 carbon atoms, or aromatic groups having the following general formula ##STR1##

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.