MODIFIED POLYPROPYLENE AND A PREPARATION METHOD THEREFOR, A SEPARATOR AND A PREPARATION METHOD THEREFOR, AND A LITHIUM-SULFUR BATTERY

Disclosed is a preparation method for modified polypropylene, comprising the following steps: dissolving polypropylene in a solvent; and adding a Lewis acid and an initiator into the solution in which the polypropylene is dissolved, and then performing a grafting reaction, to obtain the modified polypropylene; wherein the Lewis acid is selected from at least one of boron trifluoride diethyl etherate, boron trifluoride methyl ether, boron trifluoride acetic acid and boron trifluoride propionic acid; and the initiator is an organic peroxide initiator. Further disclosed are modified polypropylene prepared by the described method, a separator and a preparation method therefor, and a lithium-sulfur battery. Lewis acid monomers are grafted onto molecules of the modified polypropylene provided in the present disclosure, and therefore the modified polypropylene is suitable for being prepared into a separator of a lithium-sulfur battery, and can improve the electrochemical performance of the lithium-sulfur battery.