Patent ID: 8580419

Claim:
An organic/inorganic composite separator for a secondary battery comprising: an organic layer selected from the group consisting of a polyethylene layer, a polypropylene layer, a polyethylene/polypropylene bilayer, a polyethylene/polypropylene/polyethylene trilayer, a polypropylene/polyethylene/polypropylene trilayer, and an organic fiber filter paper layer; and an inorganic layer comprising inorganic particles and a modifying agent, wherein the inorganic particles comprise an OH group and at least one selected from the group consisting of alumina, titanium oxide, zirconium oxide, zinc oxide, silicon dioxide, and magnesium oxide; the modifying agent comprises at least one functional group selected from the group consisting of phosphonate, phosphate, phosphonic acid, and carboxylic acid; a molar ratio of the OH group of the inorganic particles and the functional group of the inorganic modifying agent is from 5:1to 10:1; and at least one surface of the organic layer is coated with the inorganic layer.