Patent ID: 7625669
Filing Date: 2009-12-01
Classification: H01M,Y02E

Abstract:
1. A lithium secondary battery comprising an electrode assembly composed of: a cathode comprising a cathode active material, a conductive material, and a binder, an anode comprising an anode active material, a conductive material, and a binder, a separator, and a lithium electrolyte, wherein at least one of the cathode and the anode further comprises an additive comprising a polyether urethane compound prepared by suspension polymerization of a polyol compound and a diisocyanate compound which is decomposed over 4.5 volts of the battery and contains a urethane group in a molecular structure thereof, and which is present in an amount of 1 to 10 percent by weight, based on the weight of the cathode or the anode, respectively; wherein the urethane group has a moiety prepared from polyethylene glycol or polypropylene glycol and a moiety prepared from toluene diisocyanate or diphenylmethane diisocyanate; and wherein the binder is selected from the group consisting of polyvinylidene fluoride, polyvinyl alcohols, carboxymethylcellulose, starch, hydroxypropylcellulose, regenerated cellulose, polyvinyl pyrollidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene terpolymer, sulfonated ethylene-propylene-diene terpolymer, styrene butadiene rubber, and fluoro rubber.