EFFECTS OF Mg2+ CONTAMINANT AT CATHODE ON PEMFC ELECTROCHEMICAL PERFORMANCE AND ELECTROCHEMICAL IMPEDANCE
During long-term operation,the components(such as bipolar plates and elastomeric gaskets)of proton exchange membrane fuel cell(PEMFC)may degrade and produce the metal ion contaminants(e.g.Ca2+,Mg2+).This could affect the long-term stability and durability of the PEMFC for its applications.In this paper,polarization curves and electrochemical impedance spectroscopy(EIS)were investigated experimentally by introducing the various concentration(i.e.100 mg/L,300 mg/L and 500 mg/L)Mg2+ solutions into the cathode air stream of the PEMFC,and then the effects of Mg2+ contaminant at the cathode on the PEMFC electrochemical performance and electrochemical impedance were analyzed.The polarization curve results show that the cathodic Mg2+ contaminant with three levels of concentrations had significantly negative effects on the electrochemical performance of the fuel cell,the current density of the fuel cell contaminatedby Mg2+decreased,andthecurrentdensitydecreasedmoredrasticallywiththeincreaseof Mg2+concentrationand contamination time.The theoretical analysis results of polarization curves indicate that the cathodic Mg2+ contaminant with three levels of concentrations could affect the permeability of the proton exchange membrane and increase the H+ impedance in the proton exchange membrane,and the performance of the proton exchange membrane deteriorated more severely with the increase of contamination time.The EIS results show that the cathodic Mg2+ contaminant with three levels of concentrations could increase the H+ impedance in the proton exchange membrane and the cathode Faraday resistance,and the H+ impedance in the proton exchange membrane and cathode Faraday resistance increase with the increase of contamination time,and the cathode electric double-layers are not significantly affected by the Mg2+ contaminant at the cathode in this work.
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