Local degradation analysis of a real long-term operated DMFC stack MEA

Understanding degradation of the membrane electrode assembly (MEA) of direct methanol fuel cells (DMFC) is important technically and scientifically for the advancement of this technology. In this work, we carry out a spatially resolved investigation of the degradation of an MEA, which has been degraded through its operation lifetime. The MEA has an active area of 320 cm(2) and has been used in operation of a DMFC stack for more than 3000 h to power a lift truck. The analysis of degradation with respect to the local position of the flow field pattern was carried out by cutting the MEA into small pieces that are characterized in a 1 cm(2) sized test cell with a reference electrode setup. The characterization techniques involved measurement of anode and cathode polarization curves, electrode potential relaxation curves after current interruption, MeOH-stripping voltammograms, cyclic voltammetry and SEM/EDX analysis. The MEA pieces were prepared by Laser ablation technique to realize the reference electrodes. The analysis yielded an independence of performance from the local position of the MEAs within the stack in terms of the anode and cathode flow fields. (C) 2012 Elsevier B.V. All rights reserved.