Asymmetric polymer electrolyte membranes for water management of fuel cells

Water management is one of the critical issues of polymer electrolyte membrane fuel cells because dehydration of a membrane increases membrane-resistance whereas excessive water flooding at the cathode impedes the gaseous diffusion of oxygen to reaction sites at the wetted catalyst surface. In this study, we have developed an asymmetric polymer electrolyte membrane that facilitates water management. The structural modification of the membrane strongly affected water management, due primarily to the fact that water must move through the membrane during fuel cell operation. The asymmetric membrane improved transport of water from the cathode to the anode when the hydrophilic side of the membrane located to the cathode, thereby enhancing overall fuel cell performance under both fully humidified and non-humidified conditions.