PEM内水和质子扩散的分子动力学模拟

DIFFUSION PROCESSES OF WATER AND PROTON IN PROTON EXCHANGE MEMBRANE USING MOLECULAR DYNAMICS SIMULATION

为了研究Nafion膜的微细观结构及其输运特性,本文针对目前广为采用的Nafion 117膜并基于MaterialsStudio(MS)软件平台构建了一种分子动力学计算模型,对其实施了计算,得到了不同含水量下Nafion 117膜的元胞结构,膜元胞的密度的模拟值与实验值吻合较好;同时研究了水分子和水合氢离子在膜内的扩散,水分子和水合氢离子的扩散系数随着含水量的增加而增加,和实验值变化趋势一致。分析了计算结果与文献实验值出现偏差的原因,并指出目前利用分子动力学方法对质子交换膜(PEM)进行微观研究仍不失为有力的手段。

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.