Patent ID: 11952475
Assignee: CELGARD, LLC
Field: Chemical engineering (Chemistry)
Classification: CPC B  C  H  Y | IPC C  H

Claim 0:
1. A dry process polymer membrane adapted for use as or in a separator for a lithium battery, including at least one mesoporous, microporous, or nanoporous impregnated membrane film, with at least one area of surfaces of pores in the polymer membrane having a first thin layer of at least a first impregnate material, comprising a polymer resin (B) as a major component therein wherein the polymer resin (B) is polyvinylidene difluoride (PVdF), polycarbonate (PC) or a combination thereof, at least an about 10% impregnation depth into the thickness of the polymer membrane, and wherein the membrane film has a polymer resin (A) as a major component; and,
and, wherein the dry process polymer membrane has a composite splittiness index of greater than 140 measured where composite splittiness index is defined by the equation below where composite splittiness index is a function of the first load peak, the second load peak, TD tensile strength, MD tensile strength, and TD elongation measured during puncture strength testing:

CSI=(A−|B−A|1.8)×C×(D×E)/106 

where:
A=First Load Peak/(Thickness×(1−% Porosity));
B=Second Load Peak/Thickness;
C=TD Elongation;
D=MD Tensile Strength;
E=TD Tensile Strength; and
where First and Second Load Peak are in units of gram-force, thickness values are in microns, MD and TD tensile strength are in gram-force, and TD elongation is expressed as percentage; and
wherein the dry process polymer membrane comprises groups of pores between adjacent lamellae with the lamellae oriented substantially along a transverse direction and fibrils or bridging structures between the adjacent lamellae oriented substantially along a machine direction and an outer surface of at least some of the lamellae being substantially flattened or planar.