Multilayer separator for lead-acid batteries

• US 20030054236A1
• Filed: 02/14/2002
• Published: 03/20/2003
• Est. Priority Date: 09/20/2001
• Status: Active Grant

• Current Assignee: Daramic LLC (Asahi Kasei Corporation)
• Original Assignee: Daramic LLC (Asahi Kasei Corporation)
• Inventors: Zucker, Jerry
• Granted Patent: US 6,703,161 B2
• Time in Patent Office: Days
• US Class Current: 429/145
• CPC Class Codes: H01M 50/417 Polyolefins
• CPC Class Codes: H01M 50/437 Glass
• CPC Class Codes: H01M 50/44 Fibrous material
• CPC Class Codes: H01M 50/446 Composite material consisting of a mixture of organic and inorganic materials
• CPC Class Codes: H01M 50/466 U-shaped, bag-shaped or folded
• CPC Class Codes: H01M 50/491 Porosity
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product
• CPC Class Codes: Y10T 29/49108 Electric battery cell making

Abstract

The invention concerns a battery separator comprising at least one first fibrous layer, at least one second fibrous layer, and at least one microporous polymer layer which is sandwiched between at least two fibrous layers, wherein said microporous polymer layer has an average pore size of less than 1 μm and wherein said at least one first fibrous layer has a thickness of at least 0.6 mm.

Claims

1. A lead-acid battery separator comprising at least one first fibrous layer, at least one second fibrous layer, and at least one microporous polymer layer which is sandwiched between at least two fibrous layers, wherein said microporous polymer layer has an average pore size of less than 1 μ

m and wherein said at least one first fibrous layer has a thickness of at least 0.6 mm.

2. A battery separator according to claim 1, wherein the microporous polymer layer is a polyolefin layer.

3. A battery separator according to claim 2, wherein the polyolefin has a molecular weight of at least 600,000, a standard load melt index of substantially 0, and a viscosity number of not less than 600 ml/g.

4. A battery separator according to claim 2, wherein the polyolefin is polyethylene.

5. A battery separator according to claim 1, wherein more than 50% of the pores of the microporous polymer layer are 0.5 μ

m or less in diameter.

6. A battery separator according to claim 1, wherein the microporous polymer layer has a thickness of >

0.1 to 0.6 mm.

7. A battery separator according to claim 1, wherein the fibrous layers essentially consist of glass fibers.

8. A battery separator according to claim 7, wherein the fibrous layers comprise 20 to 40% by weight of glass microfibers having an average diameter of less than 1 μ

m and 60 to 80% by weight of coarse glass fibers having an average diameter of about 3 μ

m.

9. A battery separator according to claim 1, wherein the fibrous layers essentially consist of polymeric fibers.

10. A battery separator according to claim 9, wherein the fibrous layers comprise polymeric fibers having a diameter of 0.1 to 10 μ

m.

11. A battery separator according to claim 10, wherein at least 10% by weight of the polymeric fibers of the fibrous layers have diameters of less than 1 μ

m and at least 60% by weight of the polymeric fibers have diameters of less than 5 μ

m.

12. A battery separator according to claim 11, wherein at least 15% by weight of the polymeric fibers have diameters of less than 1 μ

m.

13. A battery separator according to claim 12, wherein the fibrous layers comprise 20 to 40% by weight of polymeric microfibers having an average diameter of less than 1 μ

m.

14. A battery separator according to claim 10, wherein the polymeric fibers have diameters ranging from 0.1 to 5 μ

m.

15. A battery separator according to claim 9, wherein the polymeric fibers are polyolefin fibers.

16. A battery separator according to claim 15, wherein the polyolefin is polyethylene and/or polypropylene.

17. A battery separator according to claim 1, wherein the fibrous layers comprise a mixture of glass fibers and polymeric fibers.

18. A battery separator according to claim 17, wherein the fibrous layers comprise glass fibers having a diameter of 0.1 to 10 μ

m.

19. A battery separator according to claim 18, wherein the glass fibers have diameters ranging from 0.1 to 5 μ

m.

20. A battery separator according to claim 17, wherein the fibrous layers comprise polymeric fibers having a diameter of 0.1 to 10 μ

m.

21. A battery separator according to claim 20, wherein the polymeric fibers have diameters ranging from 0.1 to 5 μ

m.

22. A battery separator according to claim 17, wherein the polymeric fibers are polyolefin fibers.

23. A battery separator according to claim 22, wherein the polyolefin is polyethylene and/or polypropylene.

24. A battery separator according to claim 1, comprising a first fibrous layer having a thickness of 0.6 to 2.7 mm.

25. A battery separator according to claim 1, comprising a first fibrous layer having a thickness of 0.6 mm to 1.5 mm.

26. A battery separator according to claim 1, comprising a second fibrous layer having a thickness of 0.1 to 3.3 mm.

27. A battery separator according to claim 1, having the form of a pocket with an open top, a closed bottom and closed sides.

28. A valve-regulated lead-acid battery comprising at least two oppositely charged electrodes in a closed case, a body of an electrolyte and a separator between adjacent ones of said electrodes, wherein said separator is a separator according to claim 1 and wherein said separator is arranged in such a way that the fibrous layers of the separator are in contact with said electrodes, the first fibrous layer having a thickness of at least 0.6 mm facing the negative electrode.

29. A method of producing a lead-acid battery, said method comprising the steps of providing at least one first electrode plate with a fibrous layer wrap, pocketing the at least one electrode plate wrapped in a fibrous layer in a pocket made of microporous polymer material, combining the pocketed electrode plate with at least one second electrode plate which is wrapped in a fibrous layer, introducing the at least one first and at least one second electrode plates into a suitable case, introducing into the case a suitable quantity of electrolyte, and closing the case, said at least one first and at least one second electrode plate being arranged in such a way that the fibrous layers and microporous polymer layers form at least one separator according to claim 1.