Water Vapor Exchange Flow Channels to Enhance the Performance of Polymer Electrolyte Fuel Cells without Cathode Humidification

Abstract

Polymer electrolyte fuel cells (PEFCs) generally have external humidifiers to feed humidified hydrogen and air for membrane hydration. The external humidifiers should be omitted to develop a very simplified PEFC system with increased total efficiency and reduced cost. In the present study, a water vapor exchange flow channels installed in the PEFC thus has been developed to enhance the performance without cathode humidification. A gas diffusion layer (GDL) coated with a hydrophilic microporous layer (MPL) consisting of polyvinyl alcohol (PVA) and carbon black is employed for the cathode water exchange flow channels to promote water transport from the cathode outlet wet gas to the anode inlet dry gas. This is effective for the membrane hydration, enhancing PEFC performance. Addition of hydrophilicity to the MPL is effective to water transport from the cathode to the anode.