Low Ew Poly [Perfluorosulfonic Acids] /Phosphotungstic Acid /Teflon® Supported Membrane Electrode Assemblies

Operating proton exchange membrane fuel cells (PEMFCs) at elevated temperatures (\u3e100°C) simplifies heat rejection, and results in more useful waste heat. Membrane electrode assemblies were developed to obtain high-performance at elevated temperatures and low relative humidity (RH). Two different fabrication procedures of catalyst coated membranes (CCMs) using 750 EW poly [perfluorosulfonic acid] ionomer composite membranes that contain phosphotungstic acid are discussed in this study. Cell polarization was obtained at three operating conditions: 80/100/75, 100/70/70, and 120/35/35 (cell temperature °C/anode %RH/:athode %RH), and ambient pressure. Hydrogen/air cell performances at 120/35/35 and 400 mA/cm2 varied with the procedure from 0.39V to 0.64 V. Utilization of different fabrication procedures has a significant effect on electrode structure and thus relative overpotential, but little influence on membrane resistance and related ohmic loss. Although much higher performance occurred with the non-heat treatment process, durability issues require heat treatment for stabilization. Further study on the physical and chemical properties of the fabrication process of 750EW poly [perfluorosulfonic acid] ionomers/phosphotungstic acid CCMs is necessary to optimize both the performance and durability of elevated temperature and low relative humidity CCMs. ©The Electrochemical Society