Acceleration of Liquid Water Removal from Cathode Electrode of PEFC by Combination of Channel Hydrophilization and Diffusion Medium Perforation

Abstract

To accelerate through-plane water removal from catalyst layer (CL) to gas channel in polymer electrolyte fuel cells (PEFCs), this study presented the novel combinational structure with hydrophilized channel and perforated gas diffusion electrode (GDE). The effect of channel hydrophilization on the water droplet behavior in a PEFC was firstly investigated with cross-sectional visualization method. Furthermore, the performance enhancement induced by introducing the combinational structure was demonstrated under high-current and high-humidity operations. The perforated electrode structure was fabricated by electric discharge machining (EDM) and manual micro-drilling technique. The influence of wettability of penetration hole on the water discharge through the diffusion medium was also discussed. It was found that hydrophilic coating on the cathode channel surface positively sucks up water droplets emerging from the GDL surface. The combinational structure of channel hydrophilization and GDE perforation further promotes the through-plane water discharge, contributing to a reduction in liquid flooding at the CL.