Effect of distribution of polytetrafluoroethylene on durability of gas diffusion backing in proton exchange membrane fuel cell

Gas diffusion backing (GDB) in proton exchange membrane fuel cell played an important role in conducting electricity, conducting air and draining water, and its durability had not been widely valued. In order to improve its durability, the ultrasonic immersion method was tried during the hydrophobic treatment of GDB and the characteristic parameters of the GDBs by different immersion methods and their effects on the performance of the single fuel cell were compared by scanning electron microscopy, sectional fluorine line-scanning and map-scanning, pore size distribution, gas permeability and fuel cell performance. Besides, the hydrophobic stability of the GDBs by different immersion methods was measured by potentiostatic oxidation and ultrasonic water washing tests. It was found that ultrasonic immersion method improved the content and the uniform distribution of polytetrafluoroethylene (PTFE) in the section of GDB, resulting in the better fuel cell performance and hydrophobic stability.