fabrication and evaluation of ptfe-bonded platinum electrodes for space flight application
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Fabrication and Evaluation of PTFE-Bonded Platinum Electrodes for Space Flight Application. Joshua Johnston, South Carolina Governor’s School for Science and Mathematics Dr. Xinyu Huang, University of South Carolina, Department of Mechanical Engineering. Background. - PowerPoint PPT PresentationTRANSCRIPT
Fabrication and Evaluation of PTFE-Bonded Platinum
Electrodes for Space Flight Application
Joshua Johnston, South Carolina Governor’s School for Science and Mathematics
Dr. Xinyu Huang, University of South Carolina, Department of Mechanical Engineering
Background
Oxidation-Reduction ReactionAnode CathodeElectrolyte
Figure 1. Fuel Cell Schematic
BackgroundNASA has developed hydrogen-oxygen fuel
cells for space flight applicationSupply electrical power and potable water
during space flight. Polymer electrolyte membrane fuel cells
(PEMFC’s) Provides the long-term stability and durability
BackgroundProton conductive membranes are interfaced
with an electrodeUnsupported platinum catalyst for durability. Platinum blackPolytetraflouroethylene (PTFE) to manage
water
Purpose
To develop membrane electrode assemblies that meet operation standards set by NASA, which are 200 mA/cm2 with hydrogen and oxygen under 30 psi (relative) pressure.
The long term objective of this project is to develop high performance membrane electrode assemblies that can meet or exceed NASA’ s performance objectives.
Methods Catalyst Formulation Catalyst Depositon
Figure 2. Ultrasonic Dispersion Figure 3. Catalyst Deposition
Methods (Continued)
Elimination of surfactantsIonomer Deposition
Figure 4. Heating GDE’s Figure 5. GDE with ionomer coating
Methods (Continued)
Electrode AttachmentCell Assembly
Figure 6. Heated Compression of GDE and ionomer.
Figure 7. Fuel Cell Assembly
Methods (Continued)
Cell Testing
Figure 8. Fuel Cell Testing
Results
0 100 200 300 400 500 6000.000.100.200.300.400.500.600.700.800.901.001.10
Ambient H2-O21 atm b.p.2 atm b.p.
Current Density (mA/cm2)
Cell
Volta
ge (V
)
Figure 9. Polarization Curve of NASA 001
Results (Continued)
0 100 200 300 400 500 6000.000.100.200.300.400.500.600.700.800.901.001.10
AmbientAmbient B1 atm b.p.2 atm b.p.
Current Density (mA/cm2)
Cell
Volta
ge (V
)
Figure 10. Polarization Curve of NASA 002
Results (Continued)
0.00E+00 2.00E-01 4.00E-01 6.00E-01 8.00E-01 1.00E+00
-2.00E-01
-1.50E-01
-1.00E-01
-5.00E-02
0.00E+00
5.00E-02
Nasa 001
Potential(V)
Curr
ent (
A)
Figure 13. Cyclic Voltammetry of Nasa 001
Discussion and Conclusion
Pressurized performance Water transport issues Platinum loading PTFE loading Hydrogen Crossover
Discussion and Conclusion (continued)
In conclusion the performance standards set by NASA were not achieved in this study. However, this study did serve as a good basis for future attempts.
Future Research
Future research endeavors will attempt to optimize the fabrication of the GDE’s including: platinum loading, PTFE loading, and deposition of both the catalyst and ionomer.
Acknowledgements
South Carolina Governor’s School for Science and Mathematics
University of South CarolinaWilliam RigdonJoshua SightlerDianna Larabee Mr. LaCross