(151b) Development of Acid Doped PBI Electrolyte Membrane

Current proton-exchange membrane fuel cell (PEMFC) technology employs Nafion membranes, which suffer from costly humidity/water management requirement and low CO tolerance. High temperature PEMFCs are challenging and offer many benefits of fast reaction rate, low ohmic resistance, high tolerance to fuel impurities and high efficiency in combined heat and power (CHP) applications. We prepared PBI membrane doped with phosphoric acid (PBI/PA) for the application in high temperature PEMFCs. Detailed fuel cell performance tests were conducted using membrane electrode assembly (MEA) prepared using PBI/PA and Pt/C at different operating conditions, such as pressures, temperatures, and H₂/O₂ gas compositions. Preliminary results show that the phosphoric acid doped PBI membrane exhibited high ion conductivity (low ohmic resistance) of 0.11 and 0.24 S/cm at 120 and 160 °C, respectively, compared to 0.09 S/cm at 80 °C for Nafion. The power density output of PBI/PA MEA equipped fuel cell increased from 0.92 W/cm² to 1.15 W/cm² when the pressure was increased from 1 to 2 atm at 160 °C. Furthermore, only a slight drop in voltage of about 31 mV at 0.3 A/cm² current density was observed across the PBI/PA membranes. Preliminary results show that PBI/PA membrane is capable of operating fuel cells at working temperature greater than 120 °C without the need of water management. Some of these results will be highlighted in this presentation.