Patent ID: 7678504

Claim:
A lithium secondary battery, comprising: a positive electrode including a material that is capable of reversible intercalation/deintercalation of lithium ions as a positive active material; a negative electrode including a lithium metal, a lithium-containing alloy, a material that is capable of reversible intercalation/deintercalation of lithium ions as a negative active material or a material that is capable of reversibly forming a lithium-containing compound; a separator interposed between the positive and negative electrodes; and an electrolyte on the separator, wherein the electrolyte includes a non-aqueous organic solvent, a lithium salt, and a linear polymer having P═O bonds, wherein the linear polymer having P═O bonds is present in an amount ranging from about 0.005 to less than 5 wt % based on the total amount of the electrolyte, wherein the non-aqueous organic solvent comprises a mixed solvent of a carbonate solvent and an aromatic hydrocarbon solvent, wherein the aromatic hydrocarbon solvent is at least one selected from the group consisting of fluorobenzene, fluorotoluene, trifluorotoluene, and a compound of Formula (1): where R is a halogen, or a C 1 to C 10 alkyl, and p is an integer of 1 to 6, wherein the linear polymer having P═O bonds is formed of a polymerized phosphonate compound with a polymerizable functional unsaturated hydrocarbon group, and wherein the phosphonate compound with the unsaturated hydrocarbon group is at least one selected from the group consisting of allyl diethylphosphonoacetate (C 2 H 5 0) 2 P(O)CH 2 CO 2 CH 2 CH═CH 2 ), triethyl 3-methyl-4-phosphonocrotonate (C 2 H 5 0) 2 P(O)CH 2 C(CH 3 )—CHCO 2 C 2 H 5 ), and allyl tetraisopropylphosphonodiamidite ([[CH 3 ) 2 CH] 2 N] 2 POCH 2 CH═CH 2 ).