An Experimental Study on AC Impedance Spectroscopy of Proton Exchange Membrane Fuel Cell

Electrochemical impedance spectroscopy(EIS) is one of powerful tools for analyzing electrochemical reaction and mechanism inside proton exchange membrane fuel cell(PEMFC).A designed interference-free integration EIS system was set up for testing on the first cell at the anode of one 40-cell 1 000 W PEMFC stack with different load currents(2.5～25 A).The reported 45° line branch distortions in high-frequency range and semi-circle curves in low-frequency range which can describe cathode-flooded level were observed.A equivalent circuit model formed with R(RQ)(RQ)(RQ) and its relevant initial values were proposed to obtain the ideal fitting curves with smaller total error.The fitting result matched measured data with high degree of association in high,medium and low frequency ranges respectively.Through the analysis of tested curves and statistical data,the response discipline and its reason of operational performance of PEMFC at different current densities were discussed and explained in the aspect of electrochemical reaction and mechanism inside the PEMFC.