Anion exchange polymers and anion exchange membranes for direct ammonia fuel cells
An anion exchange polymer includes aryl ether linkage free polyarylenes having aromatic/polyaromatic rings in polymer backbone and a tethered alkyl quaternary ammonium hydroxide side groups. This anion exchange polymer may be utilized in an anion exchange process and may be made into a thin anion transfer membrane. An ion transfer membrane may be mechanically reinforced having one or more layers of functional polymer based on a terphenyl backbone with quaternary ammonium functional groups and an inert porous scaffold material for reinforcement. An anion exchange membrane may have multilayers of anion exchange polymers which each containing varying types of backbones, varying degrees of functionalization, or varying functional groups to reduce ammonia crossover through the membrane.
1. An anion membrane comprising an anion exchange polymer comprising:
aryl ether linkage free polyarylenes comprising aromatic/polyaromatic rings in a polymer backbone and a tethered alkyl quaternary ammonium hydroxide side group;
a first layer of anion exchange polymer having a first backbone, a first molecular weight and a first functional group;
a second layer of anion exchange polymer having a second backbone, a second molecular weight and a second functional group; and
wherein at least one of the second backbone, second molecular weight and second functional group are different than the first backbone, first molecular weight and first functional group;
a first microporous support scaffold; and
a second microporous support scaffold;
wherein the first layer of anion exchange polymer is configured at least partially in the first microporous support scaffold, and wherein the second layer of anion exchange polymer is configured in the second microporous support scaffold.
2. The anion exchange membrane of claim 1 , wherein the first microporous support scaffold and second microporous support scaffold are selected from the group consisting of: microporous polyethylene, polypropylene, and polytetrafluoroethylene.
3. The anion exchange membrane of claim 1 , wherein the first layer of anion exchange polymer has meta-poly(triphenylene) or para-poly(triphenylene) backbone.
4. The anion exchange membrane of claim 3 , wherein the second layer of anion exchange polymer has para-poly(triphenylene), or ortho-poly(triphenylene) backbone.
5. The anion exchange membrane of claim 1 , wherein the first layer of anion exchange polymer has trimethylammonium or piperidinium function groups.
6. An anion exchange membrane comprising:
an anion exchange polymer comprising aryl ether linkage free polyarylenes comprising aromatic/polyaromatic rings in a polymer backbone and a tethered alkyl quaternary ammonium hydroxide side group;
a first layer of said anion exchange polymer having a first backbone, a first molecular weight and a first functional group;
a second layer of anion exchange polymer and having a second backbone, a second molecular weight and a second functional group;
wherein at least one of the second backbone, second molecular weight and second functional group are different than said first backbone, said first molecular weight and said first functional group;
wherein the first layer of anion exchange polymer has trimethylammonium or piperidinium function groups; and
wherein the second layer of anion exchange polymer has pyrrolidinium or piperidinium functional groups.
7. The anion exchange membrane of claim 1 , wherein the first layer and second layer of anion exchange polymer are imbibed into said first microporous support scaffold and said second microporous support scaffold, respectively to create a reinforced anion exchange membrane.
8. The anion exchange membrane of claim 1 , wherein the total thickness of the anion exchange membrane is less than 20 microns.
9. The anion exchange membrane of claim 1 , wherein the total thickness of the anion exchange membrane is less than 5 microns.
10. The anion exchange membrane of claim 1 , wherein the first layer of anion exchange polymer contains additives selected from the group consisting of: cerium(IV) oxide, silicon dioxide, graphene, carbon nanotube, and carbon black.
11. The anion exchange membrane of claim 1 , wherein second layer of anion exchange polymer contains additives selected from the group consisting of: cerium(IV) oxide, silicon dioxide, graphene, carbon nanotube, and carbon black.
12. A direct ammonia fuel cell comprising an anion exchange membrane of claim 1 .
13. The direct ammonia fuel cell of claim 12 , wherein the anion exchange polymer is a TPN1.
14. The direct ammonia fuel cell of claim 12 , wherein the fuel cell has a power density higher than 450 mW/cm 2.