Patent ID: 8372545
Filing Date: 2013-02-12
Classification: C08J,H01M,Y02E

Abstract:
1. A method for manufacturing a microporous membrane as a battery separator for use in a lithium-ion battery containing a non-aqueous electrolyte, the battery separator therefore being resistant to thermal runaway and without shutdown, the method comprising the steps of: (a) preparing a dry-blend comprising 45% by weight of a first ultra high molecular weight (UHMW) polyethylene having an average molecular weight (Mw) of 1×10 (b) feeding the dry-blend mixture into an extruder; (c) melt-kneading the dry-blend mixture into an extruder while feeding 60% by weight of plasticizer into the dry-blend mixture, making a solution thereby; (d) extruding the solution into the form of a sheet; (e) cooling the sheet down to form a gel sheet; (f) wet-stretching the gel sheet in both machine and transverse directions to produce a stretched gel sheet containing the plasticizer; (g) extracting the plasticizer from the stretched gel sheet and drying the stretched gel sheet to form a film; and (h) heat setting the film to form the microporous membrane having no shutdown temperature.