Enhancing hydrothermal durability of gas diffusion layer by elevated temperature treatment technique for proton exchange membrane fuel cell application

Liquid water flooding is one of the major challenges in the high current density operation of proton exchange membrane fuel cells (PEMFCs). Optimizing microstructure and properties of gas diffusion layer (GDL), as an essential diffusion medium in PEMFCs, is considered as a promising approach to ensure the long-term stable operation of PEMFCs at high current densities. Herein, we report a simple elevated temperature treatment technique to enhance the hydrothermal durability and water removal capacity of GDLs. Although elevating the heat-treatment temperature from 330 degrees C (most commonly used) to 430 degrees C has no obvious impact on the GDLs' surface hydrophobicity, the GDL treated at 430 degrees C exhibits excellent hydrothermal stability and water removal capacity due to the increased dispersion of polytetrafluoroethylene (PTFE). In PEMFC, the membrane electrode assembly (MEA) containing the elevated-temperature-treated GDL could maintain high performance at high current densities and high humidity conditions. 200 h steady state test at high current densities and high humidity conditions manifests that the MEA with elevated-temperature-treated GDL is more stable and has better water removal capacity than the MEA with normal-temperature-treated GDL.