SEPARATOR COMPOSITION AND ITS PREPARATION METHOD FOR LITHIUM RECHARGEABLE BATTERY BY MEANS OF PHASE INVERSION AND UNI-AXIAL DRAWING

摘要

Provided are a method for preparing a separator for a lithium secondary battery, a separator prepared by the method which is improved in mechanical properties and ion conductivity, and a lithium secondary battery containing the separator. The method comprises the steps of adding a vinylidene fluoride-based polymer in a solvent and heating the mixture solution with stirring to prepare a uniform polymer solution; casting the obtained polymer solution on a glass plate and vaporizing the solvent in a drying oven to dry it; and putting the dried polymer in a precipitation tank filled with a non-solvent to form a pore, and uniaxially stretching it at a room temperature to prepare a separator. Preferably the separator has a thickness of 10-40 micrometers.