Cathode contamination curves

FIGURE 8.34 CV curves recorded at 50 mV/s after CV-cleaning of the fuel cell cathode contaminated with 1 ppm SO2 for 3 h at 0.7 V (dashed line) and after sulfate/bisulfate removal by holding the cathode potential at OCV (62 mV) for 30 min (solid line). Cell and humidifier temperatures are 30 C and 50 C, respectively. The flow rate is 0.25/0.03 L/min (anode/cathode). (Reprinted from Baturina, O. A. and Swider-Lyons, K. E. 2009. Journal of the Electrochemical Society 156 B1423-B1430. With permission from The Electrochemical Society, Inc.)... 

Figure 6.10. The constant current discharging curve of the PEMFC during running with different cathode gas for 100 hours. Current density 500 mA/cm cell temperature 70 °C RH anode 65 °C, and cathode 68 °C dew points, ambient pressure [34]. (Reprinted from Journal of Power Sources, 166(1), Jing F, Hou M, Shi W, Fu J, Yu H, Ming P, et al.. The effect of ambient contamination on PEMFC performance, 172-6, 2007, with permission from Elsevier.)...

Figure 23.14. Impact of ruthenium on oxygen reduction performance (a) CO stripping scans for the cathode and anode, (b) steady-state anode polarization plots before and alter contamination of the eathode, (c) H2-air steady-state polarization curves, and (d) DMFC steady-state polarization curves. Methanol concentration 0.3 M, anode potential during contamination 1.3 V vs. hydrogen counter/quasi-reference electrode, cell temperature 75 °C [65]. (Reprinted by permission of ECS— The Electrochemical Society, from Piela P, Eickes C, Brosha E, Garzon F, Zelenaya P. Ruthenium crossover in direct methanol fuel cell with Pt-Ru black anode.)...

Steady-state polarization curves of a fuel cell contaminated by toluene in the air stream. Operating conditions stoichiometry 1.5/3.0 for Hj/air RH 80% cell temperature 80°C back pressure 30 psig. MEA anode/cathode Pt loading 0.4 mg cm". (From Li, H. et al. 2008. /. Power... 

Penning et al. [10] studied the contamination effect by feeding the fuel cell cathode with four types of gases for comparison (1) pure air, (2) 1 ppm N02/air, (3) 1 ppm S02/air, and (4) a mixture of 1 ppm NO2 and 1 ppm SO2 balanced with air. Figure 3.10 shows the four performance curves of the fuel cell running for 100 h. It can be seen that the contamination effect of the gas mixture on fuel cell performance was between that of 1 ppm N02/air and that of 1 ppm S02/air, indicating that the effect of the mixed... 

All tests were conducted on a Fideris 100 W fuel cell test station, and a fresh MEA was employed for each contamination test. The steady-state polarization curves were recorded using a load bank controlled in a constant-current pattern. The relative humidity (RH) of the fuel cell was set at 80% for both anode and cathode sides. The cell temperature and backpressure were held at 80°C and 30 psig, respectively. 

FIGURE 8.14 Voltage versus time curves with various levels of toluene at different current densities. Cell temperature = 80°C, Relative humidity = 80%, 30 psi back pressure, stoichiometry 1.5/3.0 for Hj/air. (Reprinted from Journal of Power Sources, 185, Li, H. et al. Polymer electrolyte membrane fuel cell contamination Testing and diagnosis of toluene-induced cathode degradation, 272-279, Copyright (2008), with permission from Elsevier.)... 

Another consequence of membrane contamination by cationic impurity can be a decrease in the limiting current on polarization curve measured at high contamination levels. Due to proton deficiency at the cathode, the ORR current may become limited by diffusion of protons, but not oxygen diffusion through the CCL. This effect observed in experimental systems (Uribe et al, 2002 Halseid et al, 2006b) was qualitatively described using model assumptions proposed by Kienitz et al. (2009). 

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