Patent ID: 8951677
Filing Date: 2015-02-10
Classification: H01M,Y02E,Y02T,Y10T

Abstract:
1. A microporous membrane comprising at least one layer, the layer comprising polymethylpentene having an MFR of 22.0 dg/min to 28.0 dg/min and a Tm of 223.0° C. to 230.0° C. in an amount of 22.0 wt. % to 40.0 wt. % based on the weight of the layer, wherein the membrane further comprises polyethylene having an Mw of 1.0×10 5 to 2.0×10 6 and a Tm ≧130.0° C., the membrane having an air permeability ≦1.0×10 3 seconds/100 cm 3 /20 μm, a TD heat shrinkage at 105° C. ≦2.1%, and a TD heat shrinkage at 130° C. <25.0%.