The degradation of PFSA membranes in fuel cells is a critical factor for fuel cell life time. Ex situ methods for determining the degradation processes have been used extensively, mainly radically initiated from gas or liquid phase. Gas phase degradation has proven to cause cleavage of the main polymer chain causing the degradation speed to increase. In this study decomposition products washed out in the water form both gas and liquid phase degradation experiments have been analyzed. Decomposition products were pre-concentrated using solid phase extraction (SPE) and analyzed with HPLC-MS. The distribution of decomposition products is significantly different for gas phase and liquid phase degradation. The same analysis procedure is applied on water condensed during fuel cell operation. The HPLC-MS chromatogram showed that the condition inside a fuel cell operating at optimal conditions, most probably is less harsh than those in both liquid and gas phase ex situ degradation experiments.
Increased life-time of the proton conducting membrane of polymer electrolyte membrane fuel cells is the key to improve the endurance of fuel cell stacks. Here we present a Raman spectroscopy investigation of a fully fluorinated sulfonated membrane from a 1500h FC steady-state experiment compared with Nafion® membranes aged in hydrogen peroxide and Fenton's solution. The latter approach as an attempt to develop a screening method based on accelerated ageing. In all membranes degradation is evident. The Raman results of the fuel cell tested membrane demonstrate a loss of functional sulfonic acid groups throughout the membrane. The accelerated ageing, on the other hand, results in degradation readily observed: e.g. loss of polymer material, opaque areas, and brittleness. Notably, the relative concentration of functional sulfonic groups stays constant, indicating that the accelerated ageing methods primarily attack the backbone of the membrane.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.