Preparation of graded microporous layers for enhanced water management in fuel cells

Abstract The newly prepared gas diffusion layer (GDL) was studied in this article. The new GDL mainly includes a carbon paper layer and two microporous layers (MPLs) on the same side of carbon paper. The two MPLs were fabricated by using conductive carbon blacks of two different carbon morphology, Vulcan XC‐72, and acetylene black carbon, respectively. From the results of the water contact angle and conductivity, it was found that the GDL prepared by spraying has not only good hydrophobicity but also low resistivity. Polarization curve and electrochemical impedance spectroscopy indicated that the spraying sequence of two different carbon black pastes seriously affects the fuel cell performance, and the mercury intrusion test proved that the change in the fuel cell performance is due to the change in the pore‐size distribution of the newly prepared GDL. By comparing with commercial GDL29BC, the GDL first sprayed with a layer of acetylene black carbon and then a layer of Vulcan XC‐72 has more pore size of 7–20 μm and 20–100 μm to improve the water and gas management capability of proton exchange membrane fuel cells. When the humidity is 60%, the maximum power density is increased by 25%, and when the humidity is 100%, it is increased by 12%.