Fuel cell water management via reduced anode reactant pressure
A method is provided for operation of a fuel cell with improved water management by maintaining reduced anode pressure relative to cathode pressure, relative to atmospheric pressure, or both. Typically, the fuel cell comprises a membrane electrode assembly comprising nanostructured thin film cathode catalyst.
1. A method of operating a fuel cell comprising a membrane electrode assembly having an anode supplied with a gaseous anode reactant at an anode pressure and a cathode supplied with a gaseous cathode reactant at a cathode pressure, wherein the anode pressure is below atmospheric pressure.
2. The method according to claim 1 wherein the anode pressure is less than the cathode pressure by at least 50 kPa.
3. The method according to claim 1 wherein the anode pressure is less than the cathode pressure by at least 150 kPa.
4. The method according to claim 1 wherein the anode pressure is less than the cathode pressure by at least 200 kPa.
5. The method according to claim 1 wherein the difference between anode pressure and cathode pressure is maintained for at least 10 minutes of continuous service.
6. The method according to claim 1 wherein the anode pressure is lower than a maximum pressure which is 90 kPa or less.
7. The method according to claim 6 wherein the anode pressure is at least 10 kPa.
8. The method according to claim 6 wherein the anode pressure is maintained below the maximum pressure for at least 10 minutes of continuous service.
9. The method according to claim 6 wherein the anode pressure is maintained below the maximum pressure for <1 minute of continuous service.
10. The method according to claim 6 wherein the fuel cell comprises an anode flow field with a reactant pressure drop of <90 kPa wherein the anode pressure is maintained below the maximum pressure.
11. The method according to claim 6 wherein the fuel cell comprises an anode flow field with a reactant pressure drop of <50 kPa wherein the anode pressure is maintained below the maximum pressure.
12. The method according to claim 6 wherein the fuel cell comprises an anode flow field with a reactant pressure drop of <25 kPa wherein the anode pressure is maintained below the maximum pressure.
13. The method according to claim 6 wherein the fuel cell comprises an anode flow field with a reactant pressure drop of <10 kPa wherein the anode pressure is maintained below the maximum pressure.
14. The method according to claim 1 wherein the fuel cell comprises a membrane electrode assembly comprising nanostructured film cathode catalyst.
15. The method according to claim 1 wherein the fuel cell comprises a membrane electrode assembly comprising an anode gas diffusion layer and a cathode gas diffusion layer where a microporous layer of the anode GDL is thinner than a microporous layer of the cathode GDL.
16. The method according to claim 1 wherein the fuel cell system comprises a anode reactant recirculation system capable of maintaining anode reactant pressure less than atmospheric pressure.