Diffusion processes of water and proton in proton exchange membrane using molecular dynamics simulation

In this paper a molecular dynamics calculation model for the Nafion 117 membrane is constructed by Materials Studio (MS) software platform to study its micro-structure and transport properties. Based on the calculation model, cell structures of different water content of Nafion 117 membrane are obtained and the predicted density values of simulated cell are in good agreement with experimental data. Meanwhile, the diffusion processes of water molecules and hydrogen ions in the membrane are studied, respectively. The predicted diffusion coefficients of both water molecules and hydrogen ions increase with the water content, which agrees well with the variation trend of experimental data. The reasons for the deviation between numerical results and the experiment values in literature are analyzed.