Experimental and Simulation Investigation of Sulfonated Aromatic Polymers as High Performance Polyelectrolyte Membranes for Fuel Cell Applications

Fuel cells product direct current by using an electrochemical process. In direct methanol fuel cells (DMFCs) and hydrogen fuel cells (HFCs) the protonexchange membrane (PEM), which provides protonic communications between the anode and cathode, is often considered as the key part of such configurations [1]. Thecommon membrane materials for HFCs and DMFCs applications are the perfluorinated ionomers such as Nafion. Due to the relatively high cost of manufacturingand high methanol permeability (in DMFCs), the utilization of Nafion membranes is limited. So a lot of researcheshave been devoted to find new alternative membranes instead of Nafion [2]. In this regard, the aromatic polymers such as sulfonated Poly(2,6-dimethyl-1,4-phenylene oxide)(SPPO) and sulfonated poly(ether ether ketone) (SPEEK) suggested and evaluated as alternative to Nafion. A seriesof SPPO and SPEEK at various degrees of sulfonation (DS) were prepared and characterized for their proton conductivity. Based on the obtained results, the optimumsamples were determined and the results were compared with Nafion117. Performance tests for a single cell, wasinvestigated for SPEEK and SPPO. Molecular dynamics simulations were also carried out more over the experimental investigations to better understand theexperimentally observed behaviour of characterized membranes at atomistic levels. Simulation results demonstrated increased segregated structure and transportproperties in Nafion membranes over SPEEK and SPPO membranes. Finally, direct comparison between experimentand simulation showed that simulated proton conductivities are in qualitative accordance with experimental measurements but they are lower than experimental valuesquantitatively. Therefore, the goal of this research is to develop polymeric membranes with low cost of production, and betterprocessability and to gain more insights into behavior of characterized Nafion, SPEEK and SPPO based membranes and finally to reproduce our experimentally obtained observations by MD simulation methods.