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.
| Original language | English |
|---|---|
| Pages (from-to) | 7037-7045 |
| Number of pages | 9 |
| Journal | ACS Nano |
| Volume | 18 |
| Issue number | 9 |
| DOIs | |
| State | Published - Mar 5 2024 |
Funding
This work was supported as part of the Joint Center for Energy Storage Research, an Energy Innovation Hub funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences. Work performed at the Advanced Photon Source and the Center for Nanoscale Materials of Argonne National Laboratory, U.S. Department of Energy Office of Science User Facilities, was supported by the U.S. DOE, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. A portion of this research used resources at the Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory. A part of this work was supported by Northern Illinois University’s Molecular Analysis Core, which was established with support from Shimadzu Scientific Instruments. T. Li is thankful for the support from U.S. National Science Foundation (Grant No. 2208972, 2120559, and 2323117). We gratefully acknowledge the computing resources provided on Bebop, a high-performance computing cluster operated by the Laboratory Computing Resource Center at Argonne National Laboratory.
Keywords
- Fourier-transform infrared spectroscopy
- Molecular dynamic simulation
- Small-angle X-ray scattering
- Small-angle neutron scattering
- Solvation structure