Lithium ion battery diaphragm base material and preparation method thereof

The invention provides a preparation method of a lithium ion battery diaphragm base material, which comprises the following steps: S1, grinding tencel chopped fibers by using grinding equipment to obtain slurry 1; s2, the pulp 1 passes through a screening-pulp grinding circulation system, and tencel fibrillated fibers with the maximum diameter smaller than 2.5 micrometers are obtained through screening; s3, sizing the tencel fibrillated fibers obtained in the step S2 through an open headbox at the concentration of 0.1-0.3%, depositing the tencel fibrillated fibers on a polyester fiber non-woven fabric along an outer inclined plate of the open headbox, performing vacuum dehydration and squeezing to obtain wet paper sheets, and drying the wet paper sheets in a drying cylinder to obtain dry paper sheets; and S4, carrying out soft calendering treatment on the dry paper sheet to obtain the lithium ion battery diaphragm base material. According to the lithium ion battery diaphragm base material prepared by the meth