Battery separators with controlled pore structure
Disclosed are battery separators comprising glass fibers and having a basis weight (gsm), a specific surface area (m 2 /g), a density (gsm/mm) and a mean pore size (μm), which satisfy the equation disclosed herein, provided that: the specific surface area is less than 1.5 m 2 /g, or the density is greater than 180 gsm/mm. Also disclosed are batteries comprising the battery separators, and processes for making the separators.
1. A battery separator comprising fibers, wherein the fibers comprise at least 5% glass fibers, and having a basis weight (in gsm), a specific surface area (in m 2 /g), a density (in gsm/mm) and a mean pore size (in μm), wherein the following equation is satisfied:
mean
pore
size
<
(
270
basis
weight
)
0.53
*
1.6
specific
surface
area
*
(
65
density
-
1.8
)
provided that:
the specific surface area is greater than 0.8 m 2 /g and less than 1.50 m 2 /g, the basis weight is greater than or equal to about 150 gsm, and the density is greater than 180 gsm/mm,
wherein the battery separator has a percent compression of less than 31% when measured according to Battery Council International Battery Technical Manual BCIS-03 (Rev. September 09) method number 1, and
wherein the percent compression is equal to ((T@ 10 kPa−T@100 kPa)/T@ 10 kPa)*100% wherein T@ 10 kPa is a thickness of the battery separator at 10 kPa and wherein T@100 kPa is a thickness of the battery at 100 kPa.
2. The battery separator of claim 1 , wherein the fibers comprise about 5% to about 50% fibers having an average diameter less than or equal to 1.0 μm.
3. The battery separator of claim 2 , wherein the fibers comprise about 15% to about 35% fibers having an average diameter less than or equal to 1.0 μm.
4. The battery separator of claim 1 , wherein the mean pore size is less than 6 μm.
5. The battery separator of claim 4 , wherein the mean pore size is less than 5 μm.
6. The battery separator of claim 4 , wherein the mean pore size is less than 4 μm.
7. The battery separator of claim 1 , wherein the density is from greater than 180 gsm/mm to about 400 gsm/mm.
8. The battery separator of claim 7 , wherein the density is from greater than 180 gsm/mm to about 220 gsm/mm.
9. The battery separator of claim 1 , wherein the wet tensile strength (MD) of the separator is about 0.01 kN/m to about 20 kN/m.
10. The battery separator of claim 9 , wherein the wet tensile strength (MD) of the separator is about 0.1 kN/m to about 3 kN/m.
11. The battery separator of claim 1 , wherein the wet tensile strength (CD) of the separator is about 0.01 kN/m to about 10 kN/m.
12. The battery separator of claim 11 , wherein the wet tensile strength (CD) of the separator is about 0.05 kN/m to about 1.5 kN/m.
13. The battery separator of claim 1 , wherein the percent recovery is greater than 84% when measured according to Battery Council International Battery Technical Manual BCIS-03A (Rev. September 09) method number 1.
14. The battery separator of claim 1 , wherein the basis weight is between 150 gsm and 1000 gsm.
15. The battery separator of claim 1 , wherein the basis weight is from about 150 gsm to about 500 gsm.
16. The battery separator of claim 1 , wherein the basis weight is greater than or equal to about 160 gsm.