Patent ID: 7947398

Claim:
An electrolyte for a secondary battery comprising an electrolyte salt and an electrolyte solvent, the electrolyte further comprising a lactam-based compound substituted with an electron withdrawing group (EWG) at a nitrogen position thereof, wherein the electron withdrawing group is selected from the group consisting of cyano group (CN), nitro group (NO 2 ), methanesulfonyl group (SO 2 CH 3 ), phenylsulfonyl group (SO 2 Ph), trifluoromethanesulfonyl group (SO 2 CF 3 ), pentafluoroethanesulfonyl group (SO 2 C 2 F 5 ), pentafluorophenyl group (C 6 F 5 ), ethyl ketone group (COC 2 H 5 ), trifluoromethyl group and methyl ester group (COOCH 3 ).