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为了探究磺化聚苯醚(SPPO)用于质子交换膜燃料电池(PEMFCs)的性质,研究了SPPO膜内部水和水合氢离子的分子扩散特性。构建含水量不同的SPPO膜的分子结构模型,采用分子动力学(MD)研究了平衡态模型的静态结构,发现元胞的密度随着含水量的增加而降低;同时通过分析径向分布函数(RDF),发现在SPPO链上的磺酸根上的硫原子周围有水分子聚集,起到吸水和传导的作用,水合氢离子也更趋向于聚集在磺酸根附近。通过对分子运动轨迹的分析,计算了水和水合氢离子在SPPO膜内的扩散系数D和电导率σ,研究结果表明,SPPO膜的电导率随着膜内水含量的增加而增加,得到了与实验符合较好的结果。
In order to investigate the properties of sulfonated polyphenylene ether (SPPO) for proton exchange membrane fuel cells (PEMFCs), the molecular diffusion properties of water and hydronium ions in SPPO membrane were studied. The molecular structure model of SPPO membranes with different water contents was constructed. The static structure of the equilibrium model was investigated by molecular dynamics (MD). The density of the cells decreased with the increase of water content. At the same time, by analyzing the radial distribution function RDF). It is found that water molecules around the sulfur atom on the SPPO chain are aggregated and play a role of water absorption and conduction. Hydronium ions also tend to accumulate in the vicinity of the sulfonate. Through the analysis of molecular motion trajectories, the diffusion coefficients D and conductivity σ of water and hydronium ions in SPPO membrane were calculated. The results show that the conductivity of SPPO membrane increases with the increase of water content in membrane, Good agreement with the experiment.