Designing a Maze-Structured Gas Diffusion Layer to Extend Water Transport Path for Enhancing the Performance and Stability of Air-Cooled Fuel Cells

The air-cooled fuel cell is a promising energy conversion device. However, the characteristics of forced convection often rapidly expel water from the gas diffusion layer (GDL) into the flow field, which reduces the humidity of the membrane electrode assembly (MEA). Under low-humidity conditions, the proton conductivity of the proton exchange membrane (PEM) decreases, thereby impairing the performance and durability of the air-cooled fuel cell. Inspired by the tortuous transport pathways in the maze model, we designed a GDL with a maze-like structure (M-GDL) to extend the water transport path, thereby increasing the internal humidity of the air-cooled fuel cell. We designed a water evaporation test to verify the water loss resistance of the GDL. The M-GDL exhibits remarkable resistance to water loss, with a rate of 0.35 mg min^-1 cm^-2, significantly lower than the 0.79 mg min^-1 cm^-2 observed for the commercial GDL. This extended water retention capability leads to a notable increase in the performance of the fuel cell, with a peak power density of 0.77 W cm^-2, which is more than double that of the commercial GDL, where the peak power density is only 0.4 W cm^-2. This work presents a strategy to mitigate the issue of low internal humidity in air-cooled fuel cells.