Collective enhancement in hydrophobicity and electrical conductivity of gas diffusion layer and the electrochemical performance of PEMFCs

Gas diffusion layer (GDL) with optimized water management capacity facilitates the electrochemical performance of proton exchange membrane fuel cells (PEMFCs). However, the impact of hydrophobicity manipulation on the mass transport capacity of GDL makes it challenging to enhance the electrochemical performance of PEMFCs effectively. In this work, we proposed a facile strategy for collectively optimizing the hydrophobicity and electrical conductivity (EC) of GDL through the hydrothermal deposition followed by a high-temperature sintering process (HDS-GDL) Specifically, surface roughness of GDL and corresponding fiber diameter firstly increases after the hydrothermal deposition (HD-GDL) and then decreases after high-temperature sintering. Surface water contact angle of the HDS-GDL (133°) increases as compared to that of the Toray GDL (CR-GDL, 125°). Meanwhile, in-plane and through-plane ECs of HDS-GDL are simultaneously enhanced as compared to the CR-GDL. Moreover, HDS-GDL with collectively enhanced hydrophobicity and ECs further improve the electrochemical performance of PEMFCs. The polarization curve implies that enhancement of the power density at the Ohmic region under a wide cathode relative humidity (RH 0–80%) is mainly dominated by the optimized hydrophobicity. The findings in this work provide a new strategy for improving the electrochemical performance of PEMFCs by precisely tailoring the water management capacity of GDL.