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

摘要

PURPOSE: A high performance separator for a lithium polymer secondary battery is provided, which is friendly to a liquid electrolyte and can induce pore-closing at a fixed temperature or higher. And a preparation method of the separator and the lithium polymer secondary battery are also provided. CONSTITUTION: The separator has a fine porous structure and 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, wherein the polyvinylidene fluoride has a weight average molecular weight of 10,000-1,000,000; dispersing a polyolefin fiber material in the resultant solution to prepare a mixture solution, wherein the polyolefin fiber material comprises polyethylene or/and polypropylene; casting the mixture solution on a substrate; melting the solvent from the cast slurry and drying. And the lithium polymer secondary battery contains a polymer electrolyte produced by impregnating the separator with a liquid electrolyte.