Battery separators comprising inorganic particles
Battery separators are generally provided. In some embodiments, the battery separators may comprise a non-woven web including a plurality of inorganic particles (e.g., silica). The non-woven web may include, in some embodiments, a plurality of relatively coarse glass fibers (e.g., having an average diameter of greater than about 1.5 microns), e.g., such that the non-woven web has a particular largest pore size and median pore size. The combination of inorganic particles with a non-woven web having features described herein may exhibit enhanced electrolyte stratification distance and/or reduced electrolyte filling time. In some embodiments, such improvements may be achieved while having relatively minimal or no adverse effects on another property of the battery separator and/or the overall battery.
1. A battery separator, comprising:
a non-woven web comprising:
a plurality of glass fibers having an average diameter of greater than or equal to about 1.5 microns, wherein the glass fibers are present in an amount of greater than or equal to about 50 wt % of the non-woven web; and
a plurality of inorganic particles,
wherein the non-woven web has a largest pore size of at least about 8 microns and less than or equal to about 25 microns, and
wherein the non-woven web has a median pore size of at least about 2.5 microns and less than or equal to about 6 microns.
2. A battery separator, comprising:
a non-woven web comprising:
a plurality of glass fibers having an average diameter of greater than or equal to about 1.5 microns, wherein the glass fibers are present in an amount of greater than or equal to about 50 wt % of the non-woven web;
a plurality of inorganic particles;
wherein the non-woven web has an acid stratification distance of less than or equal to about 5 cm; and
wherein the non-woven web has an acid filling time of less than or equal to about 200 seconds.
3. A battery separator as in claim 1 , wherein the inorganic particles are present in an amount of greater than about or equal to about 3 wt % and less than or equal to about 30 wt % of the non-woven web.
4. A battery separator as in claim 1 , wherein the plurality of inorganic particles comprise silica.
5. A battery separator as in claim 1 , wherein the plurality of inorganic particles comprise precipitated silica.
6. A battery separator as in claim 1 , wherein the plurality of inorganic particles have an average specific surface area of greater than or equal to about 100 m 2 /g and less than or equal to about 850 m 2 /g.
7. A battery separator as in claim 1 , wherein the plurality of inorganic particles have an average particle size of greater than or equal to about 0.01 micron and less than or equal to about 20 microns.
8. A battery separator as in claim 1 , wherein the plurality of glass fibers have an average diameter of greater than or equal to about 2 microns.
9. A battery separator as in claim 1 , wherein the glass fibers are present in an amount of greater than or equal to about 50 wt % and less than or equal to about 97 wt % of the non-woven web.
10. A battery separator as in claim 1 , wherein the non-woven web further comprises a plurality of synthetic fibers, wherein the synthetic fibers are present in the non-woven web in an amount of greater than or equal to about 0 wt % and less than or equal to about 20 wt %.
11. A battery separator as in claim 10 , wherein the plurality of synthetic fibers comprises bi-component fibers.
12. A battery separator as in claim 1 , wherein the non-woven web has an acid stratification distance of less than or equal to about 5 cm.
13. A battery separator as in claim 1 , wherein the non-woven web has an acid absorption at least 7 g acid/g non-woven web and less than or equal to 10 g acid/g non-woven web.
14. A battery separator as in claim 1 , wherein the non-woven web has an acid filling time of less than or equal to about 150 seconds.
15. A battery separator as in claim 1 , wherein the non-woven web has a thickness of at least about 0.05 mm and less than or equal to about 5 mm.
16. A battery separator as in claim 1 , wherein the non-woven web has an density of least about 100 g/m 2 /mm and less than or equal to about 250 g/m 2 /mm.
17. A battery separator as in claim 1 , wherein the non-woven web has an overall specific surface area of at least about 1 m 2 /g and less than or equal to about 100 m 2 /g.
18. A battery separator as in claim 1 , wherein the non-woven web has a tensile strength in the machine direction of the non-woven web greater than or equal to about 0.2 lbs/in and less than or equal to about 20 lbs/in.
19. A battery separator as in claim 1 , wherein the non-woven web has a puncture strength of at least about 1 N and less than or equal to about 20 N.
20. A battery separator as in claim 1 , wherein the non-woven web has a pressure loss of at least about 15% and less than or equal to about 30%.
21. A battery separator as in claim 1 , wherein the non-woven web has a percent thickness loss at 10 kPa of less than or equal to 30%.
22. A battery separator as in claim 1 , wherein the non-woven web has a percent thickness loss at 50 kPa of less than or equal to 7.8%.
23. A battery separator as in claim 1 , wherein the plurality of particles have an acid weight loss of less than 20%.
24. A battery separator as in claim 1 , wherein the non-woven web has a largest pore size of at least about 8 microns and less than or equal to about 18 microns.
25. A battery separator as in claim 1 , wherein the non-woven web has a median pore size of at least about 2.5 microns and less than or equal to about 4.5 microns.
26. A lead acid battery comprising the battery separator of claim 1 .