基于介观分析的纳米石墨毡水自扩散

Study on Water Self-diffusion in Nanographite Felt at Meso-scale

目的研究全钒液流电池(VRB)电极中水的自扩散行为.方法基于martini力场原理,使用material studio软件构建水和电极的粗粒化模型,用介观动力学的方法研究温度、毛细管占总模型的质量分数、毛细管的长度对水在石墨毡电极中自扩散行为的影响,通过均方位移分析不同因素对水自扩散系数的关系,通过径向分布函数分析不同因素对水在模型中有序性的影响.结果随着温度的升高,水在电极中的自扩散系数增大,有序性降低;毛细管长度增加,水在电极中的自扩散系数降低,有序性不变;毛细管占总模型的质量分数增加会增大水在石墨毡中的自扩散系数,降低水在电极中的有序性.结论所得结果与实验值进行比较,处于同一数量级,模型结果可靠.

The behavior of water self-diffusion in an all vanadium redox flow battery （ VRB ） elec- trode was studied in this paper. Based on the principle of martini force field, the coarse graining model of water and electrodes were constructed by materials studio software, and the influence of the temperature, the mass fraction of the capillary, and the length of the capillary on the water self- diffusion behavior was analyzed in the graphite felt electrode using mesoscopic dynamics method. The relationship between different factors and water self-diffusion coefficient was investigated by analyzing the mean square displacement, and the influence of different factors on the ordering of water in the model was analyzed by employing the radial distribution function. With the increase of temperature, water self diffusion coefficient in the electrode increased, and the ordering decreased. With the capillary length increased, the self-diffusion coefficient of water in the electrode was re-duced, the ordering remained unchanged. With the mass fraction of the capillary increased, the cap- illary for water self-diffusion behavior in the graphite increased, and reduced the ordering of water in electrode. The simulation results were compared with the experimental data, and showed the same tendency and magnitude, proved the reliability of the model.