Proton conducting materials
The description includes materials that may be useful for fuel cell applications such as in the manufacture of fuel cell electrodes, proton exchange membranes (PEM), as catalyst additives or in tie layers designed to be thermally and chemically robust while operating within a fuel cell's harsh environment at higher temperatures and to conduct protons, with significantly higher levels of bound acidic groups, while in a low hydration state. Methods of making the materials are also described.
1. A polymer electrolyte composition comprising a polymer having pendent groups according to formula V:
—(—SO 2 —NZ—SO 2 —R f —) m —(SO 3 Y) p (V)
wherein the polymer is highly fluorinated;
where m is 1-6; p is at least 1; and Y is chosen from the group consisting of a monovalent cation, and a polyvalent cation;
wherein R f is a multivalent fluorochemical group selected from the group consisting of (i) a highly fluorinated alkylene, (ii) a perfluoroalkylene, and (iii) a perfluoroether; which are branched, unbranched, or cyclic; and
wherein Z is chosen from the group consisting of a monovalent cation, and a polyvalent cation, wherein the composition is a suspension or a solution.
2. The polymer electrolyte composition of claim 1 wherein the polymer is perfluorinated.
3. The polymer electrolyte composition of claim 1 wherein the R f group is a (—CF 2 —) n group, wherein n is 3 and m is 1.
4. The polymer electrolyte composition to claim 1 wherein said pendent groups are according to formula VI:
—R 3 —SO 2 —NZ—SO 2 (CF 2 ) n SO 3 Y (VI)
where n is 1-6; Y is chosen from the group consisting of a monovalent cation, and a polyvalent cation; and R 3 is a branched or unbranched highly fluorinated aliphatic group comprising 1-15 carbon atoms and 0-4 oxygen atoms; and
wherein Z is chosen from the group consisting of a monovalent cation, and a polyvalent cation.
5. The polymer electrolyte composition of claim 1 further comprising a polar solvent.
6. The polymer electrolyte composition of claim 1 further comprising a stabilizing additive.
7. The polymer electrolyte composition of claim 6 wherein the stabilizing additive comprises an element selected from the group consisting of Mn and Ce.
8. The polymer electrolyte composition of claim 1 wherein R f is a multivalent fluorochemical group perfluoroalkylene.
9. A composite membrane comprising a porous support matrix, wherein the pores are substantially impregnated with the polymer electrolyte composition according to claim 1 .
10. A method of making a polymer according to claim 1 comprising the step of reacting a polymer having pendent groups according to formula VII:
—CF 2 —SO 2 —NH 2 (VII)
with a compound according to formula II:
FSO 2 (CF 2 ) n SO 2 F (II)
where n is 1-6.
11. A method of making a polymer according to claim 1 comprising the step of reacting a polymer having pendent groups according to formula VIII:
—CF 2 —SO 2 F (VIII)
with a compound according to formula IX:
HSO 3 (CF 2 ) n —SO 2 —NH 2 (IX)
where n is 1-6.
12. A polymer electrolyte comprising a polymer cast from the polymer electrolyte composition according to claim 1 .
13. An electrode comprising the polymer electrolyte according to claim 12 .
14. A polymer electrolyte membrane comprising the polymer electrolyte according to claim 12 .
15. A membrane electrode assembly comprising the polymer electrolyte membrane according to claim 13 .
16. The polymer electrolyte composition of claim 1 , wherein Z is selected from the group consisting of H+, cations of alkali metals, cations of alkaline earth metals, and alkylammonium cations.
17. The polymer electrolyte composition of claim 4 , wherein Z is selected from the group consisting of H+, cations of alkali metals, cations of alkaline earth metals, and alkylammonium cations.