Patent ID: 7682751
Filing Date: 2010-03-23
Classification: H01M,Y02E

Abstract:
1. A lithium ion secondary battery comprising a positive electrode containing a composite lithium oxide, a negative electrode capable of absorbing and desorbing lithium ions, a sheet-like separator interposed between said positive electrode and said negative electrode, a non-aqueous electrolyte and a porous electron-insulating film attached to the surface of said negative electrode, wherein said separator is a monolayer film comprising a polypropylene resin or a multilayer film whose layer to be in contact with the positive electrode comprises a polypropylene resin, said porous electron-insulating film consists essentially of an inorganic oxide filler selected from the group consisting of aluminum oxide, silicon oxide, magnesium oxide, and zirconium oxide and a binder, and said separator has a thickness not less than 1.5 times the thickness of said porous electron-insulating film.