Asymmetric Composition of Ionic Aggregates and the Origin of High Correlated Transference Number in Water-in-Salt Electrolytes
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- Argonne National Lab. (ANL), Argonne, IL (United States). Materials Science Division and Joint Center for Energy Storage Research
- Argonne National Lab. (ANL), Argonne, IL (United States). X-ray Science Division
- Univ. of Illinois at Urbana-Champaign, IL (United States). Dept. of Nuclear, Plasma, and Radiological Engineering, Beckman Inst. for Advanced Science and Technology, Program of Computational Science and Engineering and Dept. of Electrical and Computer Engineering
- Argonne National Lab. (ANL), Argonne, IL (United States). X-ray Science Division; Northern Illinois Univ., DeKalb, IL (United States). Dept. of Chemistry and Biochemistry
"Water-in-salt" electrolytes open up exciting new avenues for expanding the electrochemical window of aqueous electrolytes. We investigated the solvation structure and dynamics of highly concentrated lithium bis(trifluoromethane)sulfonimide aqueous electrolyte using experimentally corroborated molecular dynamics simulations. The simulations revealed that the heterogeneous structure of the electrolyte comprises percolating networks of ion and water domains/aggregates. Interestingly, the ionic regions are composed of more TFSI- ions than Li+ ions. The Li+-ion transport mechanism was further explored. Li+ ions can hop along the coordinated TFSI- ions in the ionic aggregates. The calculated correlated transference number of the 20 m electrolyte is similar to 0.32, which is reasonably high for the high concentration due to a weak negative correlation between the motion of cations and anions within the heterogeneous microscopic domains. These molecular dynamics results connect the heterogeneous structure of the electrolyte to the correlated dynamics of the Li+ ion and provide a new understanding of the Li+-ion transport mechanism in this novel electrolyte.
- Research Organization:
- Argonne National Laboratory (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science - Office of Basic Energy Sciences - Joint Center for Energy Storage Research (JCESR)
- Grant/Contract Number:
- AC02-06CH11357
- OSTI ID:
- 1605988
- Journal Information:
- Journal of Physical Chemistry Letters, Journal Name: Journal of Physical Chemistry Letters Journal Issue: 4 Vol. 11; ISSN 1948-7185
- Publisher:
- American Chemical SocietyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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