Patent ID: 8470898
Filing Date: 2013-06-25
Classification: H01M,Y02E

Abstract:
1. A method of making a separator that, in a lithium ion battery, is sandwiched between a negative electrode and a positive electrode to provide an electrically insulative physical barrier that mechanically separates the two electrodes, the method comprising: forming a polymer slurry into a wet thin-film layer of a desired thickness, the polymer slurry comprising a polymer solvent in which a polymer material is dissolved and hydrophobic-treated ceramic particles are dispersed, the hydrophobic-treated ceramic particles having diameters that range from about 0.005 μm to about 15 μm; exposing the wet thin-film layer to a polymer non-solvent to form a solvent-exchanged thin-film precipitated polymer layer in which at least 70 wt. % of the polymer solvent contained in the wet thin-film layer is replaced with the polymer non-solvent; and heating the solvent-exchanged thin-film precipitated polymer layer to evaporate the polymer solvent, if any, and the polymer non-solvent to form a porous thin-film polymer separator that comprises about 10 wt. % to about 95 wt. % of a polymer material matrix having opposed major face surfaces and about 5 wt. % to about 90 wt. % of the hydrophobic-treated ceramic particles distributed throughout the polymer material matrix, the polymer material matrix defining a network of interconnected pore openings that extends coextensively between the major face surfaces, the interconnected network of pore openings providing the polymer material matrix with a void volume of about 20% to about 80%.