Fn. Buchi et Gg. Scherer, IN-SITU RESISTANCE MEASUREMENTS OF NAFION(R)-117 MEMBRANES IN POLYMERELECTROLYTE FUEL-CELLS, Journal of electroanalytical chemistry [1992], 404(1), 1996, pp. 37-43
The resistance of the Nafion(R) 117 membrane in H-2/O-2 and H-2/air po
lymer electrolyte fuel cells (PEFCs) has been measured in situ using f
ast current pulses. The dependence of the membrane resistance on curre
nt density, temperature, pressure and flow-field design was investigat
ed. It was found that, independent of other variations, the resistance
increases with increasing current density. When the current density i
n the cell is increased from 0.2 to 0.7 A cm(-2), the membrane resista
nce increases by up to 22%. Even on open circuit the resistance at 60
degrees C is 15%-35% higher than that measured ex situ, indicating tha
t the membrane is not fully hydrated under the fuel cell operating con
ditions. The resistance on open circuit also depends on the design of
the flow field. In a design with forced gas convection the resistance
at 60 degrees C is substantially higher (210 m Omega cm(2)) than in a
design without forced convection (186 m Omega cm(2)).