Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan.
Phys Chem Chem Phys. 2018 Jul 25;20(29):19408-19415. doi: 10.1039/c8cp02733a.
An understanding of the characteristics of ionic liquid/graphite interfaces is highly important for electrochemical devices such as batteries and capacitors. In this paper, we report microscopic studies of 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (BMIM-TFSI) on charged graphite electrodes using molecular dynamics simulations to reveal the two-dimensional arrangement of the ions and their dynamics at the interfaces. Analyses of surface distribution and mobility of ions revealed that the ion arrangement changes from a bilayer type to a checkerboard type with increasing applied potential. Whereas the bilayer type arrangement increases the ionic mobility parallel to the interfaces with the negative potential, the ions arranged in the checkerboard type tend to localize because of the increased lateral electrostatic interactions. Furthermore, we revealed that the inhomogeneity of ionic distribution at the positive potential propagates up to a few nanometers from the interface.
理解离子液体/石墨界面的特性对于电池和电容器等电化学设备非常重要。在本文中，我们使用分子动力学模拟报告了关于在带电石墨电极上的 1-丁基-3-甲基咪唑双（三氟甲烷磺酰基）亚胺（BMIM-TFSI）的微观研究，以揭示离子在界面处的二维排列及其动力学。对离子表面分布和迁移率的分析表明，随着外加电势的增加，离子排列从双层类型转变为棋盘类型。虽然在负电势下，双层类型的排列增加了平行于界面的离子迁移率，但由于增加的侧向静电相互作用，排列成棋盘类型的离子趋于局域化。此外，我们揭示了在正电势下离子分布的不均匀性从界面传播到几纳米。
