Solid polymer electrolyte composite membrane comprising plasma etched porous support
View Patent ↗A solid polymer electrolyte composite membrane and method of manufacturing the same. According to one embodiment, the composite membrane comprises a rigid, non-electrically-conducting support, the support preferably being a sheet of polyimide having a thickness of about 7.5 to 15 microns. The support has a plurality of cylindrical pores extending perpendicularly between opposing top and bottom surfaces of the support. The pores, which preferably have a diameter of about 0.1 to 5 microns, are made by plasma etching and preferably are arranged in a defined pattern, for example, with fewer pores located in areas of high membrane stress and more pores located in areas of low membrane stress. The pores are filled with a first solid polymer electrolyte, such as a perfluorosulfonic acid (PFSA) polymer. A second solid polymer electrolyte, which may be the same as or different than the first solid polymer electrolyte, may be deposited over the top and/or bottom of the first solid polymer electrolyte.
1. A method of preparing a composite membrane, said method comprising the steps of:
(a) providing a non-electrically-conductive support, said non-electrically-conductive support being made of a polymeric material;
(b) plasma etching a plurality of pores through said non-electrically-conductive support, wherein at least some of said pores are located in a peripheral portion of said non-electrically-conductive support, wherein at least some of said pores are located in a non-peripheral portion of said non-electrically-conductive support, and wherein a greater concentration of said pores are located in said non-peripheral portion than in said peripheral portion; and
(c) at least partially filling at least some of said pores with a first solid polymer electrolyte.
2. The method as claimed in claim 1 wherein said non-electrically-conductive support is a rigid member.
3. The method as claimed in claim 1 wherein said plurality of pores are arranged in a non-random pattern.
4. The method as claimed in claim 3 wherein said plurality of pores are arranged in a hexangular pattern.
5. A method of preparing a composite membrane, said method comprising the steps of:
(a) providing a non-electrically-conductive support, said non-electrically-conductive support being made of a polymeric material;
(b) plasma etching a plurality of pores through said non-electrically-conductive support, wherein said pores are unevenly distributed throughout said non-electrically-conductive support, with some of said pores being positioned in a peripheral portion of said non-electrically-conductive support and some of said pores being positioned in a non peripheral portion of said non-electrically conductive support, said pores being positioned in a greater concentration in said non-peripheral portion than in said peripheral portion; and
(c) at least partially filling at least some of said pores with a first solid polymer electrolyte.
6. The method as claimed in claim 1 wherein said pores are generally cylindrical in shape.
7. The method as claimed in claim 1 wherein said pores have a diameter of about 0.1 to 200 microns.
8. The method as claimed in claim 7 wherein said pores have a diameter of about 0.5 to 10 microns.
9. The method as claimed in claim 1 wherein said pores constitute about 5% to 95% of said non-electrically-conductive support.
10. The method as claimed in claim 9 wherein said pores constitute about 40% to 70% of said non-electrically-conductive support.
11. The method as claimed in claim 1 wherein said non-electrically-conductive support is made of a polymer selected from the group consisting of perfluorinated polymers, polyvinylidene fluoride, poly(tetrafluoroethylene), polybenzimidazole, polyphenylenesulfide, polysulfone, polyethersulfone, polyesters, polyparaphenylene, polyquinoxaline, polyarylketone, polybenzazole, polyaramid, poly(etherether-ketone), liquid crystal polymers, polyetherimide and polyimide.
12. The method as claimed in claim 11 wherein said non-electrically-conductive support is made of polyimide.
13. The method as claimed in claim 1 wherein said non-electrically-conductive support has a thickness of about 5 to 50 microns.
14. The method as claimed in claim 13 wherein said non-electrically-conductive support has a thickness of about 7.5 to 15 microns.
15. The method as claimed in claim 1 wherein said first solid polymer electrolyte is selected from the group consisting of polymer compositions that contain metal salts, polymeric gels that contain electrolyte and ion exchange resins.
16. The method as claimed in claim 15 wherein said first solid polymer electrolyte is an ion exchange resin.
17. The method as claimed in claim 15 wherein said first solid polymer electrolyte is perfluorosulfonic acid (PFSA) polymer.
18. The method as claimed in claim 17 wherein said PFSA polymer has an equivalent weight of about 200 to 2000.
19. The method as claimed in claim 18 wherein said PFSA polymer has an equivalent weight of about 500 to 1200.
20. The method as claimed in claim 1 wherein said filling step comprises completely filling at least some of said pores with said first solid polymer electrolyte, said method further comprising positioning a second solid polymer electrolyte at least one of over the top and under the bottom of said first solid polymer electrolyte.
21. A method of preparing a composite membrane, said method comprising the steps of:
(a) providing a non-electrically-conductive support, said non-electrically-conductive support being made of a polymeric material;
(b) plasma etching a plurality of pores through said non-electrically-conductive support wherein at least some of said pores are located in a peripheral portion of said non-electrically-conductive support, wherein said pores include a first group of pores and a second group of pores, said second group of pores being located around the periphery of said first group of pores, said first group of pores being arranged in a density greater than that of said second group of pores;
(c) at least partially filling at least some of said pores with a first solid polymer electrolyte, wherein said filling step comprises completely filling at least some of said pores with said first solid polymer electrolyte; and
(d) positioning a second solid polymer electrolyte at least one of over the top and under the bottom of said first solid polymer electrolyte, wherein said second solid polymer electrolyte differs from said first solid polymer electrolyte.
22. The method as claimed in claim 20 wherein said second solid polymer electrolyte is positioned over the top and under the bottom of said first solid polymer electrolyte.
23. The method as claimed in claim 1 wherein said composite membrane has a thickness of about 5 to 300 microns.
24. The method as claimed in claim 23 wherein said composite membrane has a thickness of about 10 to 75 microns.
25. The method as claimed in claim 1 wherein said non-electrically-conductive support is non-electrolytically-conductive.
26. The method as claimed in claim 1 wherein said non-electrically-conductive support is electrolytically-conductive.
27. The method as claimed in claim 26 wherein said non-electrically-conductive support comprises an anionic polymer electrolyte.
28. The method as claimed in claim 26 wherein said non-electrically-conductive support comprises a cationic polymer electrolyte.
29. The method as claimed in claim 1 wherein said first solid polymer electrolyte is impregnated with an inorganic ionic conductive materials.
30. The method as claimed in claim 1 wherein said non-electrically-conductive support has a Young's Modulus of at least approximately 2500 Mpa.
31. The method as claimed in claim 1 wherein said pore filling step comprises providing said first solid polymer electrolyte in a solution, then coating said solution into said pores of said non-electrically-conductive support, evaporating any solvent in said solution and then curing said first solid polymer electrolyte.
32. The method as claimed in claim 1 wherein said pore filling step comprises providing said first solid polymer electrolyte in a solution and then spraying said solution into said pores of said non-electrically-conductive support.
33. The method as claimed in claim 1 wherein said pore filling step comprises providing said first solid polymer electrolyte as a membrane and then pressing said membrane against said non-electrically-conductive support at a temperature above the glass transition temperature of the first solid polymer electrolyte.
34. The method as claimed in claim 1 wherein said filling step comprises completely filling at least some of said pores with said first solid polymer electrolyte, said method further comprising depositing a layer of a second solid polymer electrolyte at least one of over said top surface and under said bottom surface of said first solid polymer electrolyte.
35. The method as claimed in claim 34 wherein said first and second solid polymer electrolytes are different.
36. A method of preparing a composite membrane, said method comprising the steps of:
(a) providing a non-electrically-conductive support, said non-electrically-conductive support being made of a polymeric material;
(b) plasma etching a plurality of pores through said non-electrically-conductive support, wherein at least some of said pores are located in a peripheral portion of said non-electrically-conductive support and at least some of said pores are located in a non-peripheral portion of said non-electrically-conductive support, and wherein said pores constitute about 70% to 95% of said non-electrically-conductive support; and
(c) at least partially filling at least some of said pores with a first solid polymer electrolyte.
37. The method as claimed in claim 36 wherein said pores constitute about 95% of said non-electrically-conductive support.
38. The method as claimed in claim 36 wherein said pores constitute about 70% of said non-electrically-conductive support.