Ultra-thin gas diffusion layer with integrated hydrophobic and hydrophilic paths for enhanced water management performance of proton exchange membrane fuel cells

Abstract

Water flooding has become a barrier to achieving high energy output in proton exchange membrane fuel cells (PEMFCs) under high humidity conditions. In this study, a novel gas diffusion layer (GDL) composed of hydrophilic and hydrophobic networks is constructed through fabricating ultra-thin carbon fiber paper (CFP) via wet papermaking, which enables stable water/gas transport. The ZrO₂ fibers introduced into the hydrophobic GDL-net form hydrophilic pathways, while the residual hydrophobic nets are available for fast gas diffussion. As a result, the fuel cell peak power density based on this novel GDL is significantly improved, which is 1.95 times that of commercial GDL and 1.6 times that of the one only with hydrophobic paths. Additionally, a limiting current density as high as 4 A/cm² at 0.25 V is achieved, demonstrating that the ultra-thin GDL effectively shortens mass transport pathways. The hydrophilic regions facilitate water transport, while the hydrophobic network creates efficient channels for oxygen diffusion. This integration of hydrophilic and hydrophobic pathways in the ultra-thin GDL significantly enhances water management in PEMFCs.