| 摘要 |
PROBLEM TO BE SOLVED: To provide a lithium ion secondary battery having improved charge and discharge cycle life and manufacture thereof. SOLUTION: Polyolefin powder grains 10, having melting point of 200 deg.C or less and consisting of PE(polyethylene) or PP(polypropylene); and polymeric powders 12, such as PVDE-HFP having swelling properties by impregnation of an electrolyte are mixed with each other uniformly, a sheet of 10 to 100 microns in thickness is formed to make a separator. An electrolyte is impregnated in polymeric powders 12 after the separator has been formed. Such a separator is various in passing through direction of a lithium ion and disperses uniformly throughout the separator, and thus the occurrence of a local heavy current can be prevented. |
