| Objective: ||Design hydrocarbon-based H2/O2 fuel cell membranes for high temperature,<25 percent relative humidity, < 2.5 atm pressure, proton conductivity > 100 mS/cm, and area-specific resistance < 0.05 ohm-cm2.
|| Description: ||The current thrust in H2/O2 fuel cells power technology is driven by a critical, almost universal need for the design of PEMs which can effectively operate at high temperatures (> 120˚C), and at low relative humidity (< 25 percent); ideally, no external humidification should be required. This design, if successfully implemented, has several advantages. Minimizing water management issues simplifies the design and reduces costs. Requiring low levels of humidification would also raise the potential for enhanced dimensional stability of the membranes which, in turn, will positively impact the durability of the fuel cells performance.
Designs might consider molecular structures/mechanisms for inherent hydration which will favor water retention even at higher temperatures and thus, obviate the use of high external humidification. Nanostructuring to enhance hydrophilicity as well as models/simulation for proton conduction under low relative humidity conditions can also be considered as a part of the Phase I effort.
• Membrane proton conductivity of 50 to 100 mS/cm at 120˚C
• Area-specific resistance of < 0.05 ohm-cm2 in the fuel cells
• Durability over 5000 hours
|| ||PHASE I: Fabricate electrolyte membranes with high proton conductivities at high temperatures, requiring low relative humidity for operation. Testing should include proton conductivity, area-specific resistance, chemical composition, microstucture and durability measurements.
|| || ||PHASE II: Fabricate membrane electrode assemblies (MEAs) using the membrane technology previously developed and investigate the MEA performance. Testing should include environmental/durability tests to show stability of the MEAs. Build prototype stacked fuel cells (20 to 50 W power) using these MEAs to demonstrate power generation. It is desired that a prototype be delivered to the government for testing.
|| ||DUAL USE COMMERCIALIZATION: Military application: Developed materials may find use in portable power units, unmanned air vehicles, directed energy weapons, BA5590 etc. Commercial application: Commercial high-end applications will impact transportation as well as stationary applications. Others include microelectromechanical systems (MEMS), small power systems, and portable power systems.
|| References: ||1. Dang, T., Bai, Z., and Dalton, M., 227th ACS National Meeting, Polymer Preprint, 2004, Vol. 45, No. 1, 282.
2. Hickner, M.A., Ghassemi, H., Kim, Y.S., Einsla, B.R., McGrath, J.E., Chem. Rev. 2004, Vol. 104, pp. 4587-4612.
3. Dang, T., Dalton, M., Durstock, M., Venkatasubramanian, N., Arnold, F., PMSE Preprint, 2003, Vol. 89 No. 2, p. 508.
4. Wainright, J., Wang, J.T., Weng, D., Savinell, R.F., Litt, M., J. Electrochem. Soc., 1995, Vol. 142, p. 121.
|Keywords: ||proton exchange membrane, PEM, low RH, high temperature, proton conductivity, fuel cell, MEA |