Patent ID: 9331323
Filing Date: 2016-05-03
CPC Classification: H01M,Y02E

Claim Text:
1. A method of making a separator for a lithium-ion electrochemical cell, the method comprising: co-extruding (i) a melt of a water-curable cross-linkable polyolefin mixed with a hydrocarbon plasticizer oil and (ii) a melt of ultrahigh molecular weight polyethylene mixed with a hydrocarbon plasticizer oil to form either a two-layer structure of co-extensive films of the cross-linkable polyolefin and the ultrahigh molecular weight polyethylene or a three-layer structure of two outer layers of cross-linkable polyolefin and a central layer of ultrahigh molecular weight polyethylene, the extrudate having a shape and area for obtaining one or more separator membranes for a lithium-ion electrochemical cell; cooling the co-extruded layers to form a solid layered structure up to about five hundred micrometers in thickness; stretching the solid layered structure and extracting the hydrocarbon plasticizer oil from the solid layered structure to form a separator membrane structure having a pore volume that is 20% to 70% of the outline volume of the separator structure, the separator membrane structure having a thickness of up to 50 micrometers; and reacting the cross-linkable polyolefin with water or water vapor to cure the cross-linkable polyolefin and form a layered separator structure comprising co-extensive films of the cross-linked polyolefin and the ultrahigh molecular weight polyethylene.