Proton conducting electrolytes with cross-linked copolymer additives for use in fuel cells
AssigneesDaimler AG, Ford Motor Company
InventorsKeping Wang, Jing Li, Yunsong Yang
Life of this patent
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Abstract
A proton conducting polymer electrolyte comprising a proton conducting ionomer cross-linked with an amount of a copolymer additive comprising cross-linking functional groups and other functional groups (e.g. proton carriers, chelating agents, radical scavengers) shows improved durability over the ionomer alone and provides for more stable inclusion of these other functional groups. The copolymer additive comprises at least two types of metal oxide monomers, one having cross-linking functional groups and the other having the other functional groups.
Claims13
A method of making a proton conducting polymer electrolyte comprising a proton conducting ionomer and a polymetaloxane copolymer additive, the method comprising:
- (a) copolymerizing
- a plurality of metal oxide monomers with cross-linking functional groups and
- a plurality of metal oxide monomers with other functional groups, in random or block sequence to form the metaloxane copolymer exhibiting the cross-linking functional groups and the other functional groups, wherein:
- the metal oxide monomers with the cross-linking functional groups comprise:
- a first metal bonded to at least two oxygen atoms and selected from the group consisting of Si, Ti, Zr, Ce, Ta, and Cr;
- and
- the cross-linking functional groups bonded to the first metal and comprising a functional end group containing nitrogen or oxygen and characterized by a chemical structure selected from the group consisting of —NH2, ═NH, -(aliphatic)-OH, -(aryl)-OH,
- wherein R is a hydrocarbon group;
- and
- wherein the metal oxide monomers with the other functional groups comprise:
- a second metal bonded to at least two oxygen atoms and selected from the group consisting of Si, Ti, Zr, Ce, Ta, and Cr;
- and
- the other functional groups bonded to the second metal are selected from the group consisting of:
- i) proton carrier functional groups comprising a functional end group selected from the group consisting of —PO3H2, —COOH, —SO3H, and —SO2NHSO2CF3,
- ii) metal chelating functional groups comprising a functional end group selected from the group consisting of phosphonic acid, bipyridine, phenanthroline, and derivatives thereof, and
- iii) free radical scavenger functional groups comprising a functional end group selected from the group consisting of aminophenyl, hydroxyphenyl and derivatives thereof,
- (b) mixing an amount of (i) the polymetaloxane copolymer following copolymerization, or (ii) a mixture of the metal oxide monomers prior to copolymerization, with an amount of the proton conducting ionomer;
- and
- (c) heating the mixture such that a polymetaloxane copolymer is formed and the polymetaloxane copolymer and the proton conducting ionomer are covalently bonded or acid-base complexed together at the cross-linking functional groups of the polymetaloxane copolymer.
Dependencies are inferred from the claim text.