The Membrane-Electrode Interface in PEFCs III. The Effect of Methanol Concentration in DMFCs

The effect of methanol feed concentration on the membrane-electrode interface was investigated in polymer electrolyte fuel cells (PEFCs). The membrane-electrode interfacial resistance in direct methanol fuel cellls (DMFCs) has a strong dependence on methanol concentration with increasing methanol concentration leading to higher interfacial resistances for methanol concentrations up to 5.0 M for two distinctly different polymer systems: Nafion (1100 equivalent weight) and a sulfonated poly(arylene ether)sulfone (BPSH-30). Initial interfacial resistances are correlated with resistance increases and performance losses during fuel cell life tests. The results from this study agree with our previous studies on the membrane-electrode interface and suggest that high methanol concentrations can be used to probe interfacial failure in an accelerated aging capacity. Conductivity of Nafion has a high dependence on methanol concentration, while conductivity of BPSH-30 is almost independent of methanol concentration. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3481580] All rights reserved.