Hydrophilic and hydrophobic double MPL coated gas diffusion layer for enhanced PEFC performance under no-humidification at the cathode

Gas diffusion layers (GDLs) coated with a hydrophobic microporous layer (MPL) have been commonly used to improve the water management property of polymer electrolyte fuel cells (PEFCs). In the present study, the influence of a hydrophilic and hydrophobic double MPL on PEFC performance under no-humidification at the cathode was evaluated. The hydrophobic MPL using a PTFE (polytetrafluoroethylene) binder and the hydrophilic MPL using a PVA (polyvinyl alcohol) binder were coated on the carbon paper GDL substrate. The thin hydrophilic layer coated on the conventional hydrophobic MPL enhances the ability to prevent drying-up of the MEA, thereby enhancing PEFC performance. The hydrophilic layer is effective for conserving membrane humidity. The hydrophobic intermediate layer between the hydrophilic layer and the GDL substrate prevents removing the water in the hydrophilic layer via dry air in the substrate. Reducing the hydrophilic layer thickness to 5 μm is effective for enhancing PEFC performance. Appropriate enhancement of hydrophilicity by increasing the PVA content to 5 mass% is also effective for enhancing PEFC performance.