Separator for High Advanced Lithium Polymer Secondary Batteries, The Preparation Method thereof, and Lithium Polymer Secondary Batteries Comprising the Separator

摘要

PURPOSE: Provided are a high performance separator for a lithium polymer secondary battery, a preparation method thereof, and the lithium polymer secondary battery. The separator is friendly to a liquid electrolyte and can induce pore-closing at a fixed temperature or higher. CONSTITUTION: The separator having a fine porous structure is produced by a process comprising the steps of: dissolving a copolymer of polyvinylidene fluoride or/and vinylidene fluoride and 1-30wt% of hexafluoropropylene in a solvent; dispersing polyolefin-based micro particles in the resultant solution to prepare a mixture solution; casting the mixture solution on a substrate; melting the solvent from the casted slurry and drying. The polyvinylidene fluoride has a weight average molecular weight of 10,000-1,000,000. The polyolefin-based micro particle comprises polyethylene or/and polypropylene and has a diameter of less than 100 micrometer. And the lithium polymer secondary battery contains a polymer electrolyte produced by impregnating the separator with a liquid electrolyte.