Effect of Hot Pressing on Utilization of Catalyst in PEMFC Electrodes Fabricated via Electrospray

A lab-scale electrospraying system has been designed and spray parameters were optimized for the fabrication of electrodes with consistent and uniform catalyst loading for Proton Exchange Membrane Fuel Cell (PEMFC) applications. In order to understand the effect of electrodes designed through the electrospraying technique in PEMFC's, a series of membrane-electrode assemblies (MEA's) were prepared by varying the MEA fabrication hot-pressing parameters of pressure, temperature, and time. The evaluated performance of MEA's were varied primarily due to differences in hot pressing condition of MEA fabrication, and due to cell operating conditions. At 80°C and 100% relative humidity operating conditions, an MEA hot-pressed at 8 MPa for 390 seconds at a temperature of 150°C generated peak power density of 903 mW/cm2, current density of 1040 mA/cm2 at 0.6V, had a Tafel slope of 95.64 mV/dec, and electrochemical surface area (ECSA) of 23.96 m2/gPt. On the other hand, an MEA hot-pressed for the same length of time at the same temperature but with a lower pressure of 2.67 MPa generated higher peak power density of 1130 mW/cm2, higher current density of 1040 mA/cm2 at 0.6V, and had a Tafel slope of 90.07 mV/dec despite having a lower ECSA of 19.18 m2/gPt. Overall, results of this study support a low hot-pressing pressure as well as a high pressing temperature for producing the highest achievable performance from electrosprayed electrodes.