Internally Humidified, Lightweight, Regenerative Proton-Exchange-Membrane Fuel Cell

Power requirements for manned U.S. spacecraft missions have been provided by fuel cells powered by cryogenic hydrogen and oxygen launched from earth. For long-term missions, propellant weight makes this approach prohibitive. Regenerative H2-O2 fuel cells have been identified as an enabling technology for many long-term space applications and are particularly advantageous where high power, low weight and very long cycle life are important. Since the physical and chemical requirements of the oxygen positive electrodes differ in the charge and discharge modes, the tendency has been to separate the functions of the charge and discharge units. However, a bifunctional regenerative fuel cell is highly desirable because it would considerably lower weight and volume and increase reliability, since no separate valves for gas and water transfer between charge and discharge modes would be required. Thus, the objective of this project is to develop a new generation of bifunctional regenerative fuel cells having ultralight components and a simple means of construction. If successfully developed, it would offer substantial improvements in performance and lower cost over previously developed regenerative fuel cells. The long-term impact of the proposed effort will be broad based, since the innovations can be applied to advance the development of other electrochemical subsystems important to long-term space missions. A dual-use development approach will be followed because the technology has both NASA uses, along with commercial applications.