Abstract: To research the effect of sub-layer on selF^-humidifying performance of PEMFC, the membrane electrode assemblies with different PTFE contents and different loading amount of PTFE/C mixture in sub-layer were prepared, and then single PEMFCs were assembled for experimental studies of polarization and AC impedance. The results indicated that the peak power density of H₂/O₂ PEMFC was improved about 0.1 W/cm² when PTFE content in sub-layer increased from 24% to 35%, but its peak power density decreased with PTFE content up to 42%. However, the selF^-humidifying performance of H₂/air PEMFC increased all along. The loading amount of sub-layer had an important influence on selF^-humidifying performance of PEMFC, the peak power density of H₂/O₂ PEMFC was improved about 0.27 W/cm² when sub-layer loading amount increased from 0 to 4.0 mg/cm². Finally, the microstructures of the sub-layer were analyzed by the methods of intrusion Hg measurement and SEM.

Key words: Fuel cell, Proton exchange membrane, SelF^-humidifying, Electrode, Sub-layer