Polymer electrolytes including heteropolyacids
This disclosure provides polymer electrolytes, polymer electrolyte membranes (PEM's) and membrane electrode assemblies (MEA's) such as may be useful in fuel cells which contain or comprise polyoxometalates (POM's) or heteropolyacids (HPA's). In some embodiments the polyoxometalate, it's counterions or both may comprise Mn and/or Ce. In some embodiments the polymer electrolyte is fluorinated. In some embodiments the polymer electrolyte comprises a second acidic functional group other than a polyoxometalate. In another aspect, the present disclosure provides methods of making polymer electrolytes including methods which comprising a step of copolymerizing monomers comprising a covalently bound polyoxometalates and methods which comprise a step of covalently attaching a polyoxometalate to the polymer.
1. A polymer electrolyte membrane comprising:
a) a fluorinated polymer electrolyte;
b) a polyoxometalate; and
c) a counterion to the polyoxometalate;
wherein the polyoxometalate comprises a transition metal selected from the group consisting of Mn and Ce.
2. The polymer electrolyte composition according to claim 1 wherein the polyoxometalate comprises Mn.
3. The polymer electrolyte composition according to claim 1 wherein the polyoxometalate comprises Ce.
4. The polymer electrolyte composition according to any of claims 1 - 3 wherein the polyoxometalate is a heteropolyacid.
5. A fuel cell polymer electrolyte membrane comprising the polymer electrolyte composition of claim 1 .
6. A fuel cell membrane electrode assembly comprising the polymer electrolyte composition of claim 1 .
7. A polymer electrolyte which comprises first pendent groups which comprise a covalently bound polyoxometalate accompanied by a counterion to the polyoxometalate, wherein the polyoxometalate comprises Ce.
8. The polymer electrolyte according to claim 7 wherein the counterion to the polyoxometalate is selected from the group consisting of Mn cations and Ce cations.
9. The polymer electrolyte according to claim 7 wherein the counterion to the polyoxometalate is a Mn cation.
10. The polymer electrolyte according to claim 7 wherein the counterion to the polyoxometalate is a Ce cation.
11. The polymer electrolyte according to claim 7 which is fluorinated.
12. The polymer electrolyte according to claim 7 which comprises a second acidic functional group other than a polyoxometalate.
13. The polymer electrolyte according to claim 12 wherein the second acidic functional group is selected from the group consisting of phosphonic acids, sulfonic acids and bissulfonyl imides.
14. The polymer electrolyte according to claim 7 wherein the polyoxometalate is covalently bound to the polymer through a Ti or Zr atom.
15. The polymer electrolyte according to claim 7 wherein the polyoxometalate is covalently bound to the polymer through a silane group.
16. The polymer electrolyte according to claim 7 wherein the polyoxometalate is covalently bound to the polymer through a phosphonate group.
17. A fluorinated polymer electrolyte which comprises first pendent groups which comprise a covalently bound polyoxometalate.
18. A polymer electrolyte which comprises first pendent groups which comprise a covalently bound polyoxometalate and a second acidic functional group other than a polyoxometalate.
19. The polymer electrolyte according to claim 18 wherein the second acidic functional group is selected from the group consisting of phosphonic acids, sulfonic acids and bissulfonyl imides.
20. A polymer electrolyte which comprises first pendent groups which comprise a covalently bound polyoxometalate wherein the polyoxometalate is covalently bound to the polymer through a phosphonate group.
21. A fuel cell polymer electrolyte membrane comprising the polymer electrolyte of claim 7 .
22. A fuel cell membrane electrode assembly comprising the polymer electrolyte of claim 7 .
23. A method of making a polymer electrolyte comprising a step of copolymerizing:
a) a monomer comprising a covalently bound polyoxometalate which comprises Ce; with
b) at least one comonomer.
24. A method of making a polymer electrolyte comprising the steps of:
a) providing a polymer comprising three or more functional groups which may serve as binding sites for lacunary heteropolyacids; and
b) covalently attaching a polyoxometalate to the polymer.
25. The method according to claim 24 comprising the steps of:
a) providing a polymer comprising three or more silane groups; and
b) covalently attaching a polyoxometalate to a silane group of the polymer.
26. A method of making a polymer electrolyte comprising the steps of:
a) providing a polymer comprising phosphonic acid groups; and
b) covalently attaching a polyoxometalate to a phosphonic acid group of the polymer.
27. A polymer electrolyte which comprises first pendent groups which comprise a covalently bound polyoxometalate accompanied by a counterion to the polyoxometalate, wherein the counterion to the polyoxometalate is selected from the group consisting of Mn cations and Ce cations.
28. The polymer electrolyte of claim 27 , wherein the counterion to the polyoxometalate is a Mn cation.
29. The polymer electrolyte of claim 27 , wherein the counterion to the polyoxometalate is a Ce cation.