Effect of Operating Conditions on the Acidity of H_2/Air PEM Fuel Cells' Water

摘要

The pH of the water drained out from the cathode and the anode sides was measured using a flow pH meter connected to the exits of the anode and cathode compartments and was found to depend mainly on the cell's operating conditions and the MEA's aging condition. Aged MEA operating at low temperature - low RH condition led to a significant increase in the acidity of the water drained out from the cathode side (pH 1.8). On the other hand, the water drained out from the anode side has a pH value of 4.8 on average. Reactions that might affect the pH of the water drained out from the PEM fuel cell were studied. Membrane degradation via hydroxyl radicals (OH) was found to be the most influencing reaction that lowers the pH of water within PEM fuel cells.