The invention provides a preparation method of polyethylene microporous membranes, including mixing polyethylene and composite diluent to obtain a premix, wherein polyethylene accounts for 20wt%～60wt% and composite diluent accounts for 40wt%～80wt%; preparing primary membrane sheets through melt extrusion and cooling shaping; removing the composite diluent by extraction, followed by heat treatment to obtain polyethylene microporous membranes. The composite diluent is composed of high-temperature solvent and non-solvent, wherein the high-temperature solvent is one or more selected from myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, myristyl alcohol, cetyl alcohol, stearyl alcohol and eicosanol, and the non-solvent is one or more selected from benzophenone, diphenyl carbonate and dimethyl sulfone. The high-temperature solvent accounts for no less than 60wt% of the composite diluent. The specific composite diluent enables liquid-liquid phase separation at high polymer concentration. The obtained polyethylene microporous membrane has excellent air permeability and mechanical strength, and is suitable for lithium battery separator materials.
Area Code: CN
Application Number: CN201910914804.5
