Electrochemical Impedance Spectroscopy of Direct Methanol Fuel Cell Having Ag/Ag2SO4 Reference Electrode

In this study, we succeeded in measuring the impedance spectra at the anode and cathode during the direct methanol fuel cell power generation using a single cell having a Ag/Ag2SO4 reference electrode. When the anode impedance is measured at 20 mA cm(-2), two semicircles are observed in the high and middle frequency ranges, and the magnitude of the latter one increases with the increasing methanol concentration. At the cathode, the impedance spectra at 20 mA cm(-2) show, three semicircles. of which the magnitudes decrease with the increasing methanol concentration from 1 mol dm(-3) to 5 mol dm(-3), and increase again at 10 mol dm(-3). These results demonstrate that the increased methanol concentration magnifies the methanol oxidation reaction resistance at the anode and affects the total resistance at the cathode.