High-performance hydroxide exchange membrane fuel cells through optimization of relative humidity, backpressure and catalyst selection

Hydroxide exchange membrane fuel cells (HEMFC) are a promising power source for automobiles due to their low cost. Here we focus on improving the beginning-of-life performance of HEMFCs to a higher level with poly(aryl piperidinium) (PAP) membranes and ionomers. We find that lower RH and backpressure in anode than cathode can eliminate anode flooding and cathode dryout so that a balanced water management can be achieved. We also find that PtRu/C is a better anode catalyst than Pt/Ketjen Black due to the presence of Ru and Pt/Vulcan XC-72 is a better cathode catalyst than Pt/Ketjen Black due to its better mass transport properties. Once the preferred operating conditions and materials incorporated into the same cell, our HEMFCs achieved a peak power density of 1.89 W cm⁻² in H₂/O₂ and 1.31 W cm⁻² in H₂/air.