Water transport in polymer membranes for PEMFC

To determine the net electro-osmotic drag coefficient of Nafion 115 and Han wha membrane, we measured the fluxes of water discharged from anode and cat hode at different current densities. Also, we investigated the contribution of water supply for membrane from anode and cathode. When the cathode was humidified, water supply for membrane at low current densities was achieved via the cathode, but the contribution of the anode became more important a s current density gradually increased. The net electro-osmotic drag coeffic ient decreased sharply with current density, but it had a nearly constant v alue over 200 mA cm(-2). When the cathode was not humidified, at low curren t densities, most of water generated at cathode was supplied for membrane, but water supply from cathode at high current densities decreased proportio nately, and the net electro-osmotic drag coefficient showed larger value. ( C) 2000 Elsevier Science S.A. All rights reserved.