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DES PLAINES, Ill., Sept. 10, 2003 -- Gas Technology Institute (GTI), in a cooperative program with the Army Research Laboratory (ARL), reports that a new membrane developed by GTI for proton exchange membrane (PEM) fuel cells has substantially improved direct methanol fuel cell (DMFC) system performance.
"We've already achieved exceptional results with this new membrane using hydrogen as a fuel source and now we're achieving outstanding performance with methanol," says Bill Liss, GTI's Director, Advanced Energy Systems.
Independent testing by ARL researchers has verified that GTI's non-fluorinated membrane outperformed the standard Nafion® 117-membrane during multiple DMFC tests. ARL tested the GTI and Nafion membranes for electrical conductivity using a standard four-point conductivity test. The results indicated that the GTI membrane produced approximately 10 times greater electrical conductivity than Nafion. Improved conductivity means DMFC power systems using the GTI membrane will have lower current resistance losses (commonly referred to as IR losses), higher cell voltages, and greater power for a given cell volume.
ARL cell testing indicates that the GTI membrane, at a constant voltage, provides between 41 and 89 percent greater current output (depending on operating pressure and temperature) compared to a similar Nafion cell. Traditionally, DMFC power has been limited by a phenomenon referred to as methanol crossover (the diffusion of methanol from the anode to the cathode). Tests by GTI indicate that this new membrane has lower methanol crossover than traditional membranes.
GTI is conducting long-term membrane testing using hydrogen-air, with over 5100 hours accumulated to date in a 60-square centimeters cell and over 3000 hours to date with the membrane in a multi-cell, 360-square centimeters fuel cell stack.
"These interim results are of interest to the several companies that are developing DMFC power devices for commercial and military applications," adds Liss.
Notes Gerry Runte, GTI's Executive Director of Hydrogen and Distributed Energy Systems, "These new membranes should help accelerate the development of small portable power devices, an exciting part of the emerging fuel cell market. In addition to improving on DMFC performance, the GTI membrane technology is likely to be far less costly than what is currently available in the PEM and DMFC fuel cell market place."
Additional testing is planned by both GTI and ARL on these new membranes, including testing of stack configurations with new molded graphite and metallic plates currently being developed by GTI.
Source: Gas Technology Institute
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