Analysis of Aged Polymer Electrolyte Fuel Cell (PEFC) Components by Non Traditional Methods

Abstract

The ageing of microporous layers (MPL) of fuel cell gas diffusion layers has been quantitavely analyzed using a special atomic force microscopy technique, namely the so-called HarmoniX technique. From the change of mean adhesion force under dry and wet conditions an increased loss of polytetrafluoroethylene (PTFE) at the cathode was found. With ionic current measurement in tappingand contact mode by AFM, activated Nafion was investigated before fuel cell operation with high resolution and individual ionic channels were imaged in one cluster. These measurements were compared to the current distribution of membranes after 1600 h of fuel cell operation under OCV. Distinct current levels were found which demonstrate the existence of an interpenetrating ionic network with different branches not directly connected at the surface. SEM/EDX investigations of the specially designed fuel cells indicate an important role of platinum in degradation of membranes.