Degradation on a PTFE/Nafion membrane electrode assembly with accelerating degradation technique

Cost and durability are the main issues of Proton exchange membrane fuel cells (PEMFCs) commercializing. This study uses the accelerate degradation technique to analyze the durability of low cost PTFE/Nafion membrane electrode assembly (MEA). Before the MEA degradation experiment, the MEA must be activated at 65 degrees C until the performance is stable. Then increase the operation temperature to 80 degrees C. The experimental process for MEA degradation contains three steps in one cycle. The first step is to open circuit voltage (OCV) for 30 s under R.H. 100%. Then, set 0.6V for 150 s under R.H. 100%. The final step is to set 0.6V for 120 s under R.H. 0%. These three steps take around 5 min to complete. This MEA degradation experiment process includes the OCV, potential cycles, and R.H. cycles. This study uses the polarization curve, AC impedance, cyclic voltammetry (CV), linear sweep voltammetry (LSV), equations and equivalent circuit to analyze state of the MEA. At less than 160 experiment cycles, the result show that catalyst degradation is the main reason for the decay of MEA. After 280 cycles, the MEA begins to exhibit creep deformation due to the R.H. cycle. Electrochemical surface area and high frequency resistance can be used to estimate the degree of MEA degradation approximately. (C) 2009 Published by Elsevier Ltd on behalf of Professor T. Nejat Veziroglu.