Wettability-Gradient Gas Diffusion Layers: Enhancing Water Management in Electrochemical Hydrogen Compressors

With the growing demand for renewable energy, hydrogen stands out as a promising clean energy carrier due to its high energy density. However, its low volumetric energy density poses challenges for practical applications, necessitating advanced compression technologies. Electrochemical hydrogen compressors (EHCs) have gained significant attention for their high efficiency and absence of moving parts. This study addresses the critical issue of anode drying in EHCs by introducing a novel wettability-gradient gas diffusion layer (GDL) to enhance water management within the membrane electrode assembly. A series of GDLs with varying hydrophilic properties were developed by incorporating different mass fractions of Nafion resins into the microporous layer (MPL). A gradient-structured GDL was further engineered by tailoring the Nafion content and spatial distribution. Under 50% relative humidity (RH) and 0.3 V, the optimized GDL achieved hydrogen compression to 1.0 MPa within 62 s. Atomic force microscopy confirmed the nanoscale uniformity of the Nafion distribution. Lattice Boltzmann method simulations further validated the capillary-driven water transport mechanism. This work advances water management strategies in EHCs and provides design insights into next-generation energy conversion devices.