Impact of One Side Hydrophobic Gas Diffusion Layer on Water Removal Rate and Proton Exchange Membrane Fuel Cell Performance

摘要

Proton exchange membrane fuel cell (PEMFC) is considered to be one of the best clean power sources for transportation application. Water management is a critical issue, conventionally achieved by coating the cell components with the hydrophobic materials. In this work, the effects of one surface-coated cathode gas diffusion layer (GDL) on water removal rate, droplet dynamics, and the cell performance have been studied. The coated GDL is fabricated by coating one side of raw GDL (SpectraCarb 2050-A) with 15 wt.% of polytetrafluoroethylene (PTFE) solution but the other side remains uncoated. The raw GDL is commercial one and made of carbon fiber. The contact angles (θ) on both sides of the coated and raw GDL are measured. The pore size distribution, and capillary pressure are measured for the GDL, studied using the method of standard porosimetry (MSP). Water removal rate is measured by using a 20 ml syringe barrel, wherein a 13 mm diameter GDL token is stuck on the barrel opening. The droplets penetrating through the GDL are visualized via high speed camera to study the droplet dynamics. The PEMFC performance, water removal rate, and droplet dynamic are investigated with different GDLs: the first one, with the coated side facing to the water in the barrel and the catalyst layer (CL) in the PEMFC's cathode side; the second one, the non-coated side facing to the water in the barrel and the CL in the PEMFC's cathode side; and the last one is a raw GDL. The results show that the water removal rate and the PEMFC performance are improved when the coated side was facing water side in the barrel and the CL in the PEMFC's cathode side respectively.