Abstract
This study investigates the solvation structures and dynamics of bis(trifluoromethanesulfonyl)imide (TFSI–)-based aqueous electrolytes, focusing on Fe(TFSI)2and Fe(TFSI)3. Using advanced characterization techniques, including small-angle X-ray scattering, molecular dynamics simulations, Raman spectroscopy, Fourier-transform infrared spectroscopy, and nuclear magnetic resonance, we elucidate how the electrolyte concentration influences ion association, solvation structures, and transport properties. Our findings show that higher electrolyte concentrations promote the formation of contact ion pairs and anion networks, leading to reduced ion mobility and altered hydrogen-bonding dynamics. These insights provide a deeper understanding of solvation phenomena in TFSI-based electrolytes and contribute to the development of efficient and environmentally friendly iron electrodeposition processes.
| Original language | English |
|---|---|
| Pages (from-to) | 7359-7367 |
| Number of pages | 9 |
| Journal | Chemistry of Materials |
| Volume | 37 |
| Issue number | 18 |
| DOIs | |
| State | Published - Sep 23 2025 |
Funding
This research used resources of the Center for Functional Nanomaterials and the SMI beamline (12-ID) of the National Synchrotron Light Source II, both supported by the U.S. DOE Office of Science Facilities at Brookhaven National Laboratory under Contract No. DE-SC0012704. The FT-IR results were obtained from Northern Illinois University’s Molecular Analysis Core Laboratory (RRID:SCR_024586), established in collaboration with Shimadzu Scientific Instruments. The NMR spectrometer used to obtain partial results included in this publication was funded by the National Science Foundation through the MRI award CHE-2117776. We acknowledge Prof. Taesam Kim for valuable discussion. We thank Jiyu Su for his assistance with this project. A portion of the research was performed using computational resources sponsored by the Department of Energy’s Office of Energy Efficiency and Renewable Energy and located at the National Renewable Energy Laboratory. V.M.S. thanks Dr. Amalie Frischknecht (Sandia National Laboratory) for the insightful discussion on computing SAXS profiles from MD simulations. V.M.S. and L.C. thank Dr. Zhou Yu at the University of Alabama for helping with the force fields used in this work and for fruitful discussions on scattering intensity calculations. This work was supported as part of the Center for Steel Electrification by Electrosynthesis (C-STEEL), an Energy Earthshot Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences (BES) and Advanced Scientific Computing Research (ASCR). A portion of the research was sponsored by the Laboratory Directed Research and Development Program via the University of Tennessee-Oak Ridge Innovation Institute fellowship of the Oak Ridge National Laboratory, managed by UT-Battelle, LLC, for the U.S. Department of Energy. This research used resources of the Center for Functional Nanomaterials and the SMI beamline (12-ID) of the National Synchrotron Light Source II, both supported by the U.S. DOE Office of Science Facilities at Brookhaven National Laboratory under Contract No. DE-SC0012704. The FT-IR results were obtained from Northern Illinois University’s Molecular Analysis Core Laboratory (RRID:SCR_024586), established in collaboration with Shimadzu Scientific Instruments. The NMR spectrometer used to obtain partial results included in this publication was funded by the National Science Foundation through the MRI award CHE-2117776. We acknowledge Prof. Taesam Kim for valuable discussion. We thank Jiyu Su for his assistance with this project. A portion of the research was performed using computational resources sponsored by the Department of Energy’s Office of Energy Efficiency and Renewable Energy and located at the National Renewable Energy Laboratory. V.M.S. thanks Dr. Amalie Frischknecht (Sandia National Laboratory) for the insightful discussion on computing SAXS profiles from MD simulations. V.M.S. and L.C. thank Dr. Zhou Yu at the University of Alabama for helping with the force fields used in this work and for fruitful discussions on scattering intensity calculations. This work was supported as part of the Center for Steel Electrification by Electrosynthesis (C-STEEL), an Energy Earthshot Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences (BES) and Advanced Scientific Computing Research (ASCR). A portion of the research was sponsored by the Laboratory Directed Research and Development Program via the University of Tennessee-Oak Ridge Innovation Institute fellowship of the Oak Ridge National Laboratory, managed by UT-Battelle, LLC, for the U.S. Department of Energy.