Experimental study to distinguish the effects of methanol slip and water vapour on a high temperature PEM fuel cell at different operating conditions

The objective of this paper is to separate out the effects of methanol and water vapour on a high temperature polymer electrolyte membrane fuel cell under different temperatures (160°C and 180°C) and current densities (0.2Acm^-2, 0.4Acm^-2 and 0.6Acm^-2). The degradation rates at the different current densities and temperatures are analysed and discussed. The results are supported by IV curves and impedance spectroscopy. The individual resistance variations are extracted by equivalent circuit model fitting of the impedance spectra. The presence of water in the anode feed enhances the performance while the presence of 5% methanol tends to degrade the cell performance. However, the presence of H₂O mitigates some of the adverse effects of methanol. The effect of varying fuel compositions was found to be more prominent at lower current densities. The voltage improves significantly when adding water vapour to the anode after pure hydrogen operation at 180°C. A decrease in the total resistance corresponding to the voltage improvement is observed from the impedance spectra. There is minimal variation in performance with the introduction of 3% and 5% methanol along with water vapour in the anode feed at all current densities and operating temperatures. The overall degradation over a period of 1915h is -44μVh^-1. The test time includes 595h of test with pure H₂ and 300h test each with 15% H₂O, 3% CH₃OH+15% H₂O and 5% CH₃OH+15% H₂O at varying current densities and temperatures.