High-Water-Discharge Gas Diffusion Backing Layer of the Cathode for Direct Methanol Fuel Cells

A high-water-discharge gas diffusion backing layer (HBL) of the cathode for direct methanol fuel cells (DMFCs) was prepared by means of spreading diluted polytetrafluoroethylene (PTFE) solution on one-side of carbon paper and heat treatment at 340 degrees C for 30 min. The structural characterization of the HBL by a scanning electron microscope (SEM) and an energy-dispersive X-ray (EDX) showed that most PTFE existed on the sprayed PTFE side of the HBL. In comparison to the traditional backing layer prepared by impregnating carbon paper in diluted PTFE solution (TBL), the HBL showed higher gas permeability and water-discharging ability. The electrochemical impedance spectroscopy (EIS) of DMFC with HBL also proved better mass-transport ability than that of TBL, and a higher single-cell performance based on the HBL was obtained at 60 degrees C, 1 M methanol solution feeding at 1 mL min(-1), and ambient pressure air at 80 mL min(-1).