Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712, USA.
Department of Chemical Engineering and Institute for Computational and Engineering Sciences, University of Texas at Austin, Austin, Texas 78712, USA.
J Chem Phys. 2017 Feb 21;146(7):074902. doi: 10.1063/1.4976131.
We use all atom molecular dynamics simulations to investigate the influence of 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF) ionic liquid on the structure and transport properties of poly(ethylene oxide) (PEO) polymer electrolytes doped with LiPF salt. We observe enhanced diffusivities of the Li, PF, and BMIM ions with increasing loading of the ionic liquid. Interplay between the different ion-ion and ion-polymer interactions is seen to lead to a destabilization of the Li-PF coordination and increase in the strength of association between the Li cations and the polymer backbone. As a consequence, the polymer segmental relaxation times are shown to be only moderately affected by the addition of ionic liquids. The ionic-liquid induced changes in the mobilities of Li ions are seen to be correlated to polymer segmental relaxation times. However, the mobilities of BMIM ions are seen to be more strongly correlated to the BMIM-PF ion-pair relaxation times.
我们使用全原子分子动力学模拟来研究 1-丁基-3-甲基咪唑六氟磷酸盐（BMIMPF）离子液体对聚（环氧乙烷）（PEO）聚合物电解质掺杂 LiPF 盐的结构和输运性质的影响。我们观察到随着离子液体负载的增加，Li、PF 和 BMIM 离子的扩散系数增加。不同的离子-离子和离子-聚合物相互作用之间的相互作用导致 Li-PF 配位的不稳定性增加和 Li 阳离子与聚合物主链之间的缔合强度增加。因此，聚合物链段松弛时间仅适度受到添加离子液体的影响。离子液体诱导的 Li 离子迁移率的变化与聚合物链段松弛时间有关。然而，BMIM 离子的迁移率与 BMIM-PF 离子对松弛时间的相关性更强。
