Description: This Phase I effort seeks to produce a conductive polyethersulfone (PES) microporous membrane for fuel cell water management applications. This membrane will facilitate gas/liquid separations in regenerative fuel cells (RFC). The preferred novel approach will impart electrical conductivity to the PES itself; previous attempts at similar membrane development have only focused on applying a conductive layer to the surface of the PES membrane. This type of porous, conductive membrane would lead to improved water management for fuel cell and electrolyzer systems, and could significantly improve the performance of NASA's RFC. Such an improvement in performance could facilitate the design of smaller, lighter weight RFC systems for renewable energy storage for space applications. This project will result in the novel development of a conductive microporous membrane for NASA fuel cells and electrolyzers, and will also provide better understanding of the preparation and design of conductive membranes for other applications.

Benefits: Non-NASA applications for the conductive, microporous PES membrane are closely related to the NASA applications. For example, fuel cell system size and weight must be reduced and performance must be improved for sufficient saturation in the consumer market. The improvements in fuel cell performance resulting from the development of the conductive PES membrane could, for example, move fuel cell systems significantly closer to widespread utilization in the transportation industry. Improvements in regenerative fuel cell performance resulting from the use of the conductive, microporous PES membrane could also enhance the attractiveness of such systems for terrestrial renewable energy storage; for example, it could be possible to store renewable energy (i.e., wind and solar) for load leveling and off-peak demand applications.

Successful completion of the Phase I effort will result in the development of microporous, conductive PES membrane for water/gas separation. Currently, electrode flooding of the fuel cell cathode is a major concern; this membrane would facilitate water transport away from the cathode and lead to a reduction in mass transfer limitations. Likewise, the conductive membrane would facilitate the transport of liquid water to the fuel cell anode, which would result in an improvement in performance. The advantages that would be realized by the use of such a membrane in fuel cell and electrolyzer systems include improved water management, which leads to an improvement in system performance, and may facilitate a smaller and lighter-weight system design. A smaller and lighter-weight RFC system would be advantageous for NASA missions because the cost of launching such devices is a strong function of weight, and size limitations favor smaller energy storage devices.