Effects of Mg2+ contamination on the performance of proton exchange membrane fuel cell

Contamination ions from bipolar plates and elastomeric gaskets for degradation play an important role on the long-term stability and durability of proton exchange membrane (PEM) fuel cells. In this paper, the effects of Mg2+ contamination on PEM fuel cell performance were investigated experimentally. Five levels of Mg2+ concentrations were used in this work. Electrochemical performance tests were performed by adding the various Mg2+ concentration solutions into the anode H-2 fuel stream of the PEM fuel cell. And then scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), electron probe microanalysis (EPMA) and X-ray diffraction (XRD) were employed to study degradation mechanism of the PEM fuel cell performance for Mg2+ contamination. The test results show that both Mg2+ concentration and contamination time had significant effects on PEM fuel cell performance. The voltage and maximum power density of the PEM fuel cell decreased with the increase of Mg2+ concentration and contamination time. EDS and EPMA results indicate that the Magnesium mainly appeared in the PEM for the Mg2+ contaminating of the PEM fuel cell, and the Magnesium increased with the increasing Mg2+ concentration over time. The degradation mechanism of the PEM fuel cell performance for the Mg2+ contamination could be due to ion exchange reaction between Mg2+ and the proton of sulfonic acid groups in the PEM to form the new sulfonate structure. (C) 2019 Elsevier Ltd. All rights reserved.