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A molecular dynamics study of the binding effectiveness between undoped conjugated polymer binders and tetra-sulfides in lithium–sulfur batteries
Composites Part B: Engineering ( IF 12.7 ) Pub Date : 2020-11-19 , DOI: 10.1016/j.compositesb.2020.108531
Yihan Xu , Dong Zheng , Weixiao Ji , Nidal Abu-Zahra , Deyang Qu

Full atomistic molecular dynamics simulations are performed on tetra-sulfides and undoped conjugated polymers pernigraniline base polyaniline (PNB), leucoemeraldine base polyaniline (LEB), poly (3,4-ethylenedioxythiophene) (PEDOT) and polypyrrole (PPY) to investigate the binding effectiveness between polysulfides and polymer binders. The weight ratio between sulfur and binder in lithium–sulfur cells is considered in 1:1 v/v mixture of dioxolane/dimethoxyethane. The simulations reveal that the end group 2 of PNB can effectively bind a lithium tetra-sulfide (i.e. Li2S4) cluster or 2 out of 43 Li2S4 molecules with the effect of solvent. However, repeat units of PNB, LEB, PEDOT and PPY seem ineffective in binding solvated Li2S4 through non-bonded interaction, especially when the concentration of tetra-sulfide/binder in a local domain of the cathode is low. Therefore, polymers with this specific functional group (i.e. the end group 2 of PNB) are suggested to be further studied as potential effective binders to inhibit the shuttle effect of solvated lithium polysulfides. Also, since the solvent has considerable impact on the binding effectiveness between tetra-sulfides and binder, it is suggested to take advantage of the explicit solvation models, such as those built in this work, to predict how other influencing factors affect binding between polysulfides and polymers.



中文翻译:

锂硫电池中未掺杂共轭聚合物粘合剂和四硫化物之间结合效率的分子动力学研究

在四硫化物和未掺杂的共轭聚合物中,邻苯二胺基础聚苯胺(PNB),亮绿翡翠基础聚苯胺(LEB),聚(3,4-乙撑二氧噻吩)(PEDOT)和聚吡咯(PPY)进行了完整的原子分子动力学模拟在多硫化物和聚合物粘合剂之间。锂硫电池中硫与粘合剂之间的重量比以二氧戊环/二甲氧基乙烷的1:1 v / v混合物考虑。模拟表明,PNB的端基2可以有效地结合四硫化锂(Li 2 S 4)簇或43 Li 2 S 4中的2个。具有溶剂作用的分子。但是,PNB,LEB,PEDOT和PPY的重复单元似乎无法通过非键相互作用来键合溶剂化的Li 2 S 4,特别是当阴极局部区域中的四硫化物/粘合剂的浓度较低时。因此,具有该特定官能团的聚合物(。建议进一步研究PNB的端基2)作为抑制溶剂化多硫化锂穿梭效应的潜在有效粘合剂。另外,由于溶剂对四硫化物和粘合剂之间的结合效果有相当大的影响,因此建议利用显式溶剂化模型(如本工作中建立的模型)来预测其他影响因素如何影响多硫化物与二硫化物之间的结合。聚合物。

更新日期:2020-11-19
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