Studies on performance degradation of a direct methanol fuel cell (DMFC) in life test

Abstract

A 75 h life test of a direct methanol fuel cell (DMFC) at a low current density of 100 mA cm⁻² was carried out. Electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were applied to characterize the membrane electrode assembly (MEA) during the life test. The EIS results showed that the high frequency cell impedance of the MEA increased from 0.26 ohm cm² at the beginning of the life test to 0.37 ohm cm² at the end. SEM images of the MEA in cross-section apparently demonstrated the delamination of the electrodes from the membrane after the life test. TEM analysis of the electrocatalysts in the pre- and post-test cell revealed that the agglomeration of the metal particles in the anode was more serious than in the cathode. The results indicate that the agglomeration of electrocatalysts together with the delamination of the MEA concurrently contribute to the performance degradation of the DMFC.