Porous membranes filled with nano-particles and related methods
A membrane includes a porous membrane or layer made of a polymeric material having a plurality of surface treated (or coated) particles (or ceramic particles) having an average particle size of less than about 1 micron dispersed therein. The polymeric material may be selected from the group consisting of polyolefins, polyamides, polyesters, co-polymers thereof, and combinations thereof. The particles may be selected from the group consisting of boehmite (AlOOH), SiO 2 , TiO 2 , Al 2 O 3 , BaSO 4 , CaCO 3 , BN, and combinations thereof, or the particles may be boehmite. The surface treatment (or coating) may be a molecule having a reactive end and a non-polar end. The particles may be pre-mixed in a low molecular weight wax before mixing with the polymeric material. The membrane may be used as a battery separator.
1. A membrane comprising:
a porous or microporous membrane or layer made of a polymeric material having a plurality of surface treated and then wax-coated particles dispersed therein, wherein the wax has a molecular weight of from 800 to 5000.
2. The membrane of claim 1 , wherein the surface-treated and then wax-coated particles have an average particle size less than about 1 micron.
3. The membrane of claim 2 wherein said average particle size is less than about 500 nanometers.
4. The membrane of claim 1 , wherein the wax is a polyolefin wax.
5. The membrane of claim 1 , wherein the polyolefin wax is polyethylene, polypropylene, or a combination of polyethylene and polypropylene.
6. The membrane of claim 1 wherein said polymeric material being selected from the group consisting of polyolefins, polyamides, polyesters, co-polymers thereof, and combinations thereof.
7. The membrane of claim 6 , wherein said polyolefins is selected from the group consisting of polyethylene, polypropylene, polybutylene, polymethylpentene, co-polymers thereof, and combinations thereof.
8. The membrane of claim 1 wherein said plurality of surface-treated and then wax-coated particles comprises 0.1-30% by weight of said polymeric material.
9. The membrane of claim 1 wherein said surface-treated and then wax-coated particles comprise ceramic particles selected from the group consisting of boehmite (AlOOH), SiO 2 , TiO 2 , Al 2 O 3 , BaSO 4 , CaCO 3 , BN, and combinations thereof with a surface treatment or coating.
10. The membrane of claim 1 wherein said surface treatment comprises a molecule having a reactive end and a non-polar end.
11. A battery separator comprising the membrane of claim 1 .
12. The battery separator of claim 11 wherein said membrane is a layer of a multi-layered separator.
13. A battery comprising: a negative electrode, a positive electrode, a separator sandwiched between said negative electrode and said positive electrode, an electrolyte in communication between said negative electrode and said positive electrode, and said separator including a membrane comprising: a porous membrane or layer made of a polymeric material having a plurality of surface-treated and then wax-coated particles dispersed therein, wherein the wax has a molecular weight of from 800 to 5000.
14. The battery of claim 13 , wherein the surface-treated and then wax-coated particles have an average particle size of less than about 1 micron.
15. The battery of claim 13 , wherein the surface-treated and then wax-coated particles have an average particle size less than about 500 nm.
16. The battery of claim 13 , wherein the wax is a polyolefin wax.
17. The battery of claim 16 , wherein the polyolefin wax is polyethylene, polypropylene, or a combination of polyethylene and polypropylene.
18. A porous or microporous sheet or film membrane comprising:
a porous or microporous membrane or layer made of a polymeric material having a plurality of surface treated and then wax-coated particles dispersed therein, wherein the wax has a molecular weight of from 800 to 5000.
19. A porous or microporous tube membrane comprising:
a porous or microporous membrane or layer made of a polymeric material having a plurality of surface treated and then wax-coated particles dispersed therein, wherein the wax has a molecular weight of from 800 to 5000.
20. A porous or microporous nonwoven layer comprising:
a plurality of fibers made of a polymeric material having a plurality of surface treated and then wax-coated particles dispersed therein, wherein the wax has a molecular weight of from 800 to 5000.