Patent ID: 7879499

Claim:
An electrolyte for a lithium ion secondary battery comprising: a non-aqueous organic solvent; and a lithium salt, which is at least one selected from the group consisting of LiPF 6 , LiBF 4 , LiSbF 6 , LiAsF 6 , LiClO 4 , LiCF 3 SO 3 , LiC 4 F 9 SO 3 , LiAlO 4 , LiAlCl 4 , LiN(C p F 2p+1 SO 2 )(C q F 2q+1 SO 2 ) (where p and q are natural numbers), LiCl and LiI; and additives comprising difluoro oxalato borate (DFOB) represented by a chemical formula 1 below and fluoro ethylene carbonate (FEC)