Separators for vrla batteries and methods relating thereto

A composite battery separator for increasing the acid fill rate and decreasing the acid fill time of a VRLA battery, the separator comprising at least one nonwoven layer and at least one microporous polymer separator layer, the microporous polymer separator layer comprising a first surface and a second surface, wherein at least one of the first surface and the second surface comprises acid fill channels;

• and wherein:
• at least one of the first surface and the second surface further comprises a pattern of rib arrays oriented 0 to 90 degrees relative to each other;
• one of the first surface and the second surface further comprises vertically oriented ribs spaced 0.5-1.0 mm apart, and the surface opposite the one of the first surface and second surface comprising the vertically oriented ribs is smooth or flat;
• and/or
• one of the first surface and the second surface further comprises ribs spaced 3-6 mm apart, the ribs having a height of 0.008 to 1 mm, and the surface opposite the one of the first surface and second surface comprising the ribs is smooth or flat.

A composite battery separator, comprising

• a microporous polyolefin separator layer, comprising:
• at least one textured portion wherein the at least one textured portion forms a bimodal pore size distribution of the composite battery separator under a pressure of greater than 10 kPa.
• a first region comprising smaller micropores of submicron size, wherein the first region comprises a compressed microporous structure;
• and
• a second region comprising larger micropores having a size of 1-6 microns, wherein the second region comprises a microporous structure that is less compressed than the microporous structure of the first region.