Abstract：
The solvation structure of water-in-salt electrolytes was thoroughly studied, and two competing structures─anion solvated structure and anion network─were well-defined in recent publications. To further reveal the solvation structure in those highly concentrated electrolytes, particularly the influence of solvent, methanol was chosen as the solvent for this proposed study. In this work, small-angle X-ray scattering, small-angle neutron scattering, Fourier-transform infrared spectroscopy, and Raman spectroscopy were utilized to obtain the global and local structural information. With the concentration increment, the anion network formed by TFSI- became the dominant structure. Meanwhile, the hydrogen bonds among methanol were interrupted by the TFSI- anion and formed a new connection with them. Molecular dynamic simulations with two different force fields (GAFF and OPLS-AA) are tested, and GAFF agreed with synchrotron small-angle X-ray scattering/wide-angle X-ray scattering (SAXS/WAXS) results well and provided insightful information about molecular/ion scale solvation structure. This article not only deepens the understanding of the solvation structure in highly concentrated solutions, but more importantly, it provides additional strong evidence for utilizing SAXS/WAXS to validate molecular dynamics simulations.
摘要：
深入研究了盐包水电解质的溶剂化结构,在最近的出版物中明确定义了两个竞争结构-阴离子溶剂化结构和阴离子网络。为了进一步揭示这些高浓度电解质中的溶剂化结构，特别是溶剂的影响，选择甲醇作为本研究的溶剂。在这项工作中,小角度X射线散射，小角度中子散射,傅里叶变换红外光谱,和拉曼光谱被用来获得全球和局部结构信息。随着浓度的增加，由TFSI-形成的阴离子网络成为主导结构。同时,甲醇之间的氢键被TFSI-阴离子中断，并与它们形成新的连接。用两种不同的力场(GAFF和OPLS-AA)进行分子动力学模拟,GAFF与同步加速器小角X射线散射/广角X射线散射（SAXS/WAXS）结果一致，并提供了有关分子/离子尺度溶剂化结构的深刻信息。本文不仅加深了对高浓度溶液中溶剂化结构的理解，但更重要的是,它为利用SAXS/WAXS验证分子动力学模拟提供了额外的有力证据。
