SEPERATOR FOR LITHIUM RECHARGEABLE BATTERY AND LITHIUM RECHARGEABLE BATTERY USING THE SAME

摘要

A separator for a lithium secondary battery is provided to improve heat resistance and melt tension as compared with conventional polyethylene-based separators, to maintain the original shape upon overcharge or heat exposure by virtue of extension hardening, thereby imparting improved safety to a battery. A separator(124) for a lithium secondary battery(100) is formed of a resin composition comprising 99.0-99.95 wt% of a polypropylene polymer having a long chain branched introduced thereto and showing a melt strength of at least 200 mN, and 0.05-1.0 wt% of an antioxidant. The polypropylene polymer has a melt index of 0.1-20 g/10 min at 230 deg.C.