Investigation of degradation behavior of membrane electrode assembly with polytetrafluoroethylene/Nafion composite membrane

The main purpose of this study is to investigate the accelerated degradation of the PTFE/Nafion membrane electrode assembly through open circuit voltage and relative humidity cycling. The state of a PTFE/Nafion membrane electrode assembly is evaluated in a fuel cell by monitoring the polarization curve, AC impedance, cyclic voltammetry, and linear sweep voltammetry data over time. The experimental results are then fitted to equations of an equivalent circuit. The results of the first 160 experimental cycles show that catalyst degradation is the main cause for the decay of the membrane electrode assembly. During the 160–520th cycles, the membrane electrode assembly experiences creep deformation, which is due to relative humidity cycling. During the 640–840th cycles, the degradation causes a gradual transition from minor to major membrane cracking; after which the combustion reaction dramatically accelerates membrane electrode assembly degradation.