Performance and electrochemical characteristics of a high temperature PEMFC stack under different reformate mixtures

Proton exchange membrane fuel cells are considered one of the most feasible hydrogen energy technologies and expected to become commercial worldwide in the near future. To overcome the bottleneck of the CO tolerance and to increase the alternative options of low-cost catalysts, several types of membrane electrolyte assembly with different high temperature proton exchange membrane systems were developed and tested in single cells. In this work, a fuel cell stack with PBI/H3PO4-based membrane electrolyte assemblies were examined under simulated reformate gas conditions which are approximate to real application conditions. The stack performance and electrochemical impedance spectroscopy were measured and analyzed at different nitrogen and carbon monoxide concentrations of simulated reformate mixtures. The results show that the poison effect of carbon monoxide due to an increase of charge transfer resistance is more remarkable than the dilution effect of nitrogen due to an increase of mass transfer resistance. The tolerable carbon monoxide concentration decreases with increasing the nitrogen concentration of the simulated reformate gas. In addition, it is observed that increasing the operating temperature increases the carbon monoxide tolerance.