Method of preparing polymer electrolyte composition and method of manufacturing lithium secondary battery using the same

Abstract

Disclosed are a method of preparing a polymer electrolyte composition and a method of manufacturing a lithium secondary battery employing the same. A polymer mixture including a) a polymer mixture including polyvinylidene fluoride-based polymer and b) at least one polymer selected from the group consisting of polyacrylonitrile and polymethyl methacrylate are mixed with a solvent in which a lithium salt is dissolved. The mixing ratio of the polymer mixture and the solvent is 1: 3-10. Thus obtained first mixture is stirred at a room temperature for 1-48 hours. Then, thus obtained second mixture is heated at 60-250° C. for 5 minutes-6 hours while stirring to prepare a polymer electrolyte composition. This composition is coated on at least one substrate selected from a group consisting of a molded film, an anode and a cathode and then dried. The polymer electrolyte has a good mechanical strength and the lithium secondary battery has a stable charge/discharge characteristic and a high capacity.