Influence of Gas Diffusion Layers on PEFC Performance under No-Humidification Using Anode Gas Recirculation(Thermal Engineering)

Abstract

Polymer electrolyte fuel cells (PEFCs) generally have external humidifiers to supply humidified hydrogen and oxidant gases. If a PEFC could be operated under no-humidification, humidifiers may be removed, resulting in a simplified PEFC system with increased total efficiency and reduced cost. The present study was carried out to clarify the influence of gas diffusion layers (GDLs) on PEFC performance under no-humidification using anode gas recirculation. For the anode GDL, it is important to increase water transport between the anode gas and the membrane electrode assembly (MEA). The anode GDL without a microporous layer (MPL) is effective for enhancing PEFC performance. For the cathode GDL, it is important to maintain humidity and prevent drying-up of the MEA. A double hydrophobic MPL coated on both sides of the GDL is effective for reducing gas permeability, thereby preventing removing the water in the MEA through the GDL via dry air at the cathode. The hydrophilic layer coated on the double MPL enhances the ability of the GDL to prevent drying-up. Appropriate hydrophilic layer thickness of 40μm is effective for enhancing PEFC performance. Reducing the pore diameter of the hydrophobic intermediate layer between the hydrophilic layer and the substrate is also effective for enhancing PEFC performance.