The Effect of Anodic Reactant Relative Humidity on the Performance and EIS Response of PEM Fuel Cell

The effect of relative humidity of the anode (RHa) on proton exchange membrane (PEM) fuel cells has been studied focusing on fully humidified cathode operation condition. The amount of humidity in the fuel stream affected the cell performance, which could in turn be reflected by EIS spectra measurements. Results indicated that high power density was achieved at high relative humidity of the fuel gas. Anode relative humidity were shown to have significant effectson the AC impedance of cell. Based on the impedance spectra, charge transfer resistance, mass transfer resistance, and solution resistance can be extracted using the equivalent circuits set up. The Nyquist plots were fitted by Zview software. When anode relative humidity decreased, highohmic and charge transfer resistances could be observed. Also the capacitance parameters increase with enhancing relative humidity. With increasing of the gases pressure, solution resistance was increased. While increasing the operating pressure led to a water flooding in electrode, resulting high mass transfer resistance.

Keywords:

Relative humidity , Operation condition , Polarization curve , Electrochemical impedance spectroscopy , PEM fuel cell