Estimation of leakage current in proton exchange membrane fuel cells

In this study, the leakage current of a proton exchange membrane fuel cell is determined from the polarization curve and impedance measurements. The ohmic loss is specified from the high frequency resistance in the Nyquist plot. The polarization curve is then rotated counter-clockwise to nullify the effects of the ohmic loss. Considering the negligible mass transport loss in low current densities, the activation loss is then determined as a function of the current density. Employing the Tafel assumption, the leakage current can be determined from the best logarithmic fit. The method is then experimentally verified by measuring the polarization curves and Nyquist plots of a cell including the Nafion 212 as the membrane. Tests are conducted using four different gas diffusion layers for all of which the same current leakage is obtained.