High temperature membrane electrode assembly with high power density and corresponding method of making
A membrane electrode assembly (MEA) with enhanced current density or power density is fabricated using high temperature (HT) proton exchange membrane (PEM). The MEA can be utilized in high temperature PEM fuel cell applications. More specifically, the MEA is modified with the addition of one or more of selected materials to its catalyst layer to enhance the rates of the fuel cell reactions and thus attain dramatic increases of the power output of the MEA in the fuel cell. The MEA has application to other electro-chemical devices, including an electrolyzer, a compressor, or a generator, purifier, and concentrator of hydrogen and oxygen using HT PEM MEAs.
1. A membrane electrode assembly, comprising
a high temperature proton exchange membrane disposed between an anode electrode and a cathode electrode;
wherein a catalyst and at least one additive are disposed in a layer applied at an interface between the membrane and each of the anode and cathode electrodes
wherein the at least one additive comprises an organic or inorganic acid material, acid salt fluoropolymer, perfluoroacid electrolyte, or an ionomer in an amount of between about 1% and 15% of a weight of the catalyst at the interface;
wherein the at least one additive is in immediate contact with the catalyst thereby creating enhanced reaction kinetics at the interface, including enhanced oxygen reduction kinetics at the cathode interface; and
wherein the resulting assembly has a power density per unit area of between about 180 and 300 mW/cm 2 at 0.67V with ambient pressure H2/Air operating at 180° C.
2. The assembly of claim 1 , wherein the catalyst comprises platinum, or platinum-alloy particles.
3. The assembly of claim 1 , wherein the catalyst particles are unsupported or supported on a high surface area conductive powder material.
4. The assembly of claim 1 , wherein the at least one additive comprises a material having favorable wetting and reactionary properties with the catalyst in contact with phosphoric acid.
5. The assembly of claim 1 , wherein the resulting assembly has a power density per unit area of about 200 mW/cm 2 at 0.67V with ambient pressure H2/Air operating at 180° C.
6. A method of manufacturing a membrane electrode assembly, comprising:
co-depositing a catalyst and an additive to an interfacing surface of a first electrode and an interfacing surface of a second electrode; and
bonding or attaching the first electrode to a first side of a high temperature proton exchange membrane along the interfacing surface of the first electrode and bonding or attaching the second electrode to a second side of the high temperature proton exchange membrane along the interfacing surface of the second electrode;
wherein the additive comprises at least one additive formed of an acidic material, an ionomer, or both;
wherein the additive is in immediate contact with the catalyst thereby creating enhanced reaction kinetics at the interface surface, including enhanced oxygen reduction kinetics at the cathode interface; and
wherein the resulting assembly has a power density per unit area of between about 180 and 300 mW/cm 2 with ambient pressure H2/Air at 0.67V operating at 180° C.
7. The method of claim 6 , wherein the catalyst comprises supported or unsupported platinum.
8. The method of claim 6 , wherein the catalyst comprises platinum containing alloy particles.
9. The method of claim 6 , wherein the additive layer comprises at least one material having favorable wetting and reactionary properties with the catalyst in contact with phosphoric acid.
10. The method of claim 6 , wherein the resulting assembly has a power density per unit area of about 200 mW/em 2 at 0.67V with ambient pressure H2/Air operating at 180° C.