Membrane made of a blend of UHMW polyolefins

Patent metadata

Field	Value
Publication number	US-10790491-B2
Application number	US-201514920925-A
Country	US
Kind code	B2
Filing date	Oct 23, 2015
Priority date	Mar 22, 2006
Publication date	Sep 29, 2020
Grant date	Sep 29, 2020

Abstract

A membrane is a microporous sheet made of a blend of a first ultra high molecular weight polyolefin and a second ultra high molecular weight polyolefin. Each polyolefin has a molecular weight, both of those molecular weights are greater than 1 million, and one molecular weight is greater than the other. Additionally, the intrinsic viscosity (IV) of the membrane may be greater than or equal to 6.3.

First claim

We claim:

1. A membrane comprising a stretched microporous sheet being made from a processing oil based solution consisting of a first ultra-high molecular weight polyethylene having a first molecular weight, a second ultra-high molecular weight polyethylene having a second molecular weight, and a processing oil,
said first molecular weight and said second molecular weight being greater than 1 million and being different from one another and wherein the stretched microporous sheet has an intrinsic viscosity (IV) greater than or equal to 6.3.

2. The membrane of claim 1 , wherein said intrinsic viscosity (IV) is greater than or equal to 7.7.

3. The membrane of claim 1 , the intrinsic viscosity (IV) of said first ultra-high molecular weight polyethylene being 7<IV<15.

4. The membrane of claim 1 , the intrinsic viscosity (IV) of said second ultra-high molecular weight polyethylene being IV>15.

5. The membrane of claim 1 , the stretched microporous sheet being further made from a third polymer with an intrinsic viscosity (IV) being IV<7.

6. The membrane of claim 1 , the stretched microporous sheet having characteristics selected from the group consisting of: a thickness of less than 5 mils (125 microns); a porosity between 25 and 85%; an average pore size between 0.01-0.5 microns; a puncture strength of greater than 300 gr-force/mil (25 microns); a MacMullin Number between 6-15; a Gurley Number of less than 60 sec/10 cc/mil; and combinations thereof.

7. A battery comprising a separator, where the separator is the membrane of claim 1 .

8. The battery of claim 7 being a lithium battery.

9. A lithium battery separator membrane comprising a wet processed, stretched, microporous sheet being made from a processing oil based solution including a first ultra-high molecular weight polyethylene having a first molecular weight, a second ultra-high molecular weight polyethylene having a second molecular weight, and a processing oil, where said first molecular weight and said second molecular weight being greater than 1 million and being different from one another, and where processing oil is extracted to form pores in the wet processed, stretched, microporous sheet having an average pore size of 0.01-0.5 μm and the wet processed, stretched, microporous sheet has an intrinsic viscosity (IV) greater than or equal to 6.3.

10. The lithium battery separator membrane of claim 9 , wherein said intrinsic viscosity (IV) is greater than or equal to 7.7.

11. The lithium battery separator membrane of claim 9 , the intrinsic viscosity (IV) of the first ultra-high molecular weight polyethylene being 7<IV<15.

12. The lithium battery separator membrane of claim 9 , the intrinsic viscosity (IV) of the second ultra-high molecular weight polyethylene being IV>15.

13. The lithium battery separator membrane of claim 9 , the wet processed, stretched, microporous sheet being further made from a third polymer with an intrinsic viscosity (IV) being IV<7.

14. The lithium battery separator membrane of claim 9 , the wet processed, stretched, microporous sheet having characteristics selected from the group consisting of: a thickness of less than 5 mils (125 microns); a porosity between 25 and 85%; an average pore size between 0.01-0.5 microns; a puncture strength of greater than 300 gr-force/mil (25 microns); a MacMullin Number between 6-15; a Gurley Number of less than 60 sec/10 cc/mil; and combinations thereof.

15. The lithium battery separator membrane of claim 9 wherein the solution further includes a viscoelastic lubricant.

16. A battery comprising the lithium battery separator membrane of claim 9 .

17. The battery of claim 16 being a lithium battery.

Assignees

• Celgard Llc

Inventors

• Simmons Donald K
• Yaritz Joseph G

Classifications

• H01M10/0525 Primary

  Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries · CPC title

• H01M50/417

  Polyolefins · CPC title

• H01M50/491

  Porosity · CPC title

• H01M50/489

  Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties · CPC title

• H01M50/406

  Moulding; Embossing; Cutting · CPC title