Preparation method of polyolefin microporous diaphragm for lithium ion batteries

The invention belongs to the field of polymer functional films and preparations thereof, and particularly relates to a lithium ion battery diaphragm and a preparation method thereof. A polyolefin material is modified through the reactive extrusion of hydrophilic prepolymer and polyolefin, and then the obtained object is subjected to tape-casting and stretching, so that a hydrophilic polyolefin microporous diaphragm for lithium ion batteries is obtained. Compared with microporous membranes prepared by using unmodified polyolefin, the hydrophilicity, thermal deformation resistance and tensile properties of the polyolefin microporous diaphragm are obviously improved, and the other properties such as porosity and air permeability of the diaphragm are changed slightly.