The Impacts of Repetitive Carbon Monoxide Poisoning on Performance and Durability of a Proton Exchange Membrane Fuel Cell

In this paper, we report the effects on cell performance and durability of repeatedly poisoning the anode catalyst of a proton exchange membrane fuel cell (PEMFC) to 2 ppm carbon monoxide (CO) in the hydrogen fuel. The experiments were designed to simulate repeated exposure to low level impurities as may be experienced in a dynamically operated PEMFC. Experiments were conducted over a period of 1000 hours and accompanied by weekly diagnostics to characterize detailed changes in performance. Results for the repeatedly poisoned cell were compared to those of a control cell which was operated identically but without CO in the anode feed stream. Two effects were observed: the electro-chemically active area (ECA) of the test cell anode decreased significantly during the initial 300 hours of the experiment and the hydrogen crossover rates increased by a factor of 67 by the end of the experiment. Both effects contributed to performance losses, while the latter also indicated the end of life for the membrane electrode assembly (MEA). The results of the experiments emphasize the impact low level CO contaminant may have on MEA lifetime and cell performance under dynamic conditions.