Influence of triple MPL coated GDL on the PEFC performance under low and high humidity

Gas diffusion layers (GDLs) coated with a hydrophobic microporous layer (MPL) have been commonly used to improve water management properties of polymer electrolyte fuel cells (PEFCs). In the present study, a novel triple MPL coated GDL, in which the hydrophilic layer was coated on the hydrophobic double MPL, was developed to achieve further enhancement of the PEFC performance under both low and high humidity. Under low humidity, a hydrophilic layer is effective to conserve the humidity of the MEA, while a hydrophobic double MPL prevents the removal of water from the hydrophilic layer. The triple MPL coated GDL, in which the polytetrafluoroethylene (PTFE) content in the hydrophobic MPL in contact with the hydrophilic layer is 30 mass% and that in contact with the carbon paper substrate is 10 mass%, is effective to expel excess water at the catalyst layer, which results in a much higher performance under high humidity.