Identification of Gas Diffusion Layer PTFE Content Local Anomalies Using a Segmented Cell System

A segmented cell system was employed to investigate the impact of localized gas diffusion layer (GDL) PTFE content variations on fuel cell performance. An artificial defect was created by exchanging the standard cathode GDL with 13 wt. % PTFE located at segment 4 with a similar GDL (8, 17, 26, or 35 wt. % PTFE loading). An increase in PTFE loading caused a local performance decrease at high current density. For the 8 wt. % PTFE case, the local performance variation was relatively small. Other segments and the whole cell performance were not significantly affected by the defect. Spatially distributed data analysis with polarization and electrochemical impedance spectroscopy (EIS) revealed that such performance decreases are attributed to an increase in mass transfer overpotential ascribe to a decrease in porosity, average pore size and gas permeability with an increase in GDL defect PTFE loading.