Enhanced Stability of the Carba- closo -dodecaborate Anion for High-Voltage Battery Electrolytes through Rational Design
- Joint Center for Energy Storage Research, Argonne, Illinois 60439, United States; Material, Physical and Chemical Sciences Center, Sandia National Laboratories, Albuquerque, New Mexico 87158, United States
- Joint Center for Energy Storage Research, Argonne, Illinois 60439, United States; Energy Technologies Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Joint Center for Energy Storage Research, Argonne, Illinois 60439, United States; Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
- Joint Center for Energy Storage Research, Argonne, Illinois 60439, United States; Energy Technologies Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States; Department of Materials Science, University of California Berkeley, Berkeley, California 94720, United States
Future energy applications rely on our ability to tune liquid inter-molecular interactions and achieve designer electrolytes with highly optimized properties. In this work, we demonstrate rational, combined experimental-computational design of a new carba-closo-dodecaborate based salt with enhanced anodic stability for Mg energy storage applications. We first establish, through a careful examination using a range of solvents, the anodic oxidation of a parent anion; the carba-closo-dodecaborate anion at 4.6 V vs Mg0/2+ (2.0 vs. Fc0/+), a value lower than that projected for organic solvent-based electrolytes and lower than weakly associating bis(trifluoromethylsulfonyl)imide and tetrafluoroborate anions. Solvents such as acetonitrile, 3-methylsulfolane and 1,1,1,3,3,3-hexafluoroisopropanol are shown to enable the direct measurement of carba-closo-dodecaborate oxidation, where the resultant neutral radical drives passive film formation on the electrode. Secondly, we employ computational screening to evaluate the impact of functionalization of the parent anion on its stability and find that replacement of the carbon-vertex proton with a more electronegative fluorine or trifluoromethyl ligand increases the oxidative stability and decreases the contact-ion pair formation while maintaining reductive stability. This predicted enhanced stability of the fluorocarba-closo-dodecaborate is experimentally validated. Future work includes evaluation of the viability of these derivative anions as efficient and stable carriers for energy storage as a function of the ionic transport through the resulting surface films formation on candidate cathodes.
- Research Organization:
- Argonne National Laboratory (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- DOE Contract Number:
- AC02-06CH11357
- OSTI ID:
- 1472086
- Report Number(s):
- SAND-2018-6418J; 145421
- Journal Information:
- Journal of the American Chemical Society, Vol. 140, Issue 35; ISSN 0002-7863
- Publisher:
- American Chemical Society (ACS)
- Country of Publication:
- United States
- Language:
- English
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