Conductance and Methanol Crossover Investigation of Nafion Membranes in a Vapor-Fed DMFC

A major improvement in the performance of a direct methanol fuel cell (DMFC) can be expected with a decreasing methanol crossover from the anode to the cathode side of the cell. We know that the water and methanol uptake of Nafion and Nafion-like proton conductors is smaller from a gaseous phase than from a liquid phase and therefore the methanol concentration in the membrane itself has to be smaller. The focus of our investigations is the performance of a fuel cell with a gaseous feed of methanol/water at the anode under elevated cell temperatures. The following work investigates the conductivity of a DMFC with a polymer electrolyte membrane (Nafion 1xx) acting as the proton conductor for operating temperatures around 393 K as a function of the cell humidification parameter (pressure, relative humidity of the air). Furthermore it takes into consideration the membrane conductivity and the methanol crossover through the membrane as a function of the cell temperature.