Patent ID: 9748546
Date: 2017-08-29
CPC Classifications: H01M,Y02E

Claim:
1. A freestanding, flexible microporous polymer sheet having first and second opposite major surfaces, comprising: a polymer matrix binding a filler component, the polymer matrix including a polyolefin component of a molecular weight that provides sufficient molecular chain entanglement to form three-dimensional interconnecting and interpenetrating pore and polymer networks through which the bound filler component is distributed from the first major surface to the second major surface, the filler component exhibiting a high oil absorption capacity of greater than 285 ml of dioctyl phthalate or dibutyl phthalate per 100 grams of the filler component, when the filler component is in its initial state before the start of material processing to form the microporous polymer sheet, and the polyolefin and filler components included in amounts that result in a microporous polymer sheet having about 75% to about 90% porosity and containing less than about 10 wt. % polyolefin component.