Freestanding microporous separator including a gel-forming polymer

摘要

A freestanding battery separator includes a microporous polymer web with passageways that provide overall fluid permeability. The polymer web preferably contains UHMWPE and a gel-forming polymer material. The structure of or the pattern formed by the gel-forming polymer material and wettability of the UHMWPE polymer web result in a reduction of the time required to achieve uniform electrolyte distribution throughout the lithium-ion battery. In a first embodiment, the gel-forming polymer material is a coating on the UHMWPE web surface. In a second embodiment, the gel-forming polymer material is incorporated into the UHMWPE web while retaining overall fluid permeability. Both embodiments produce hybrid gel electrolyte systems in which gel and liquid electrolyte co-exist.