On water transport in polymer electrolyte membranes during the passage of current

► All dissolved water crosses membrane via diffusion only. ► Most published works so far are flawed due to wrong boundary conditions. ► new insight into water transport through membrane in PEM fuel cells (PEMFC). ► Demonstrate that a “water-uptake layer” has impact on water balance in a fuel cell. ► Electro-osmotic drag coefficient can be determined via in-situ FC experiments.