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Interfacial Speciation Determines Interfacial Chemistry: X-ray-Induced Lithium Fluoride Formation from Water-in-salt Electrolytes on Solid Surfaces.
- Source :
- Angewandte Chemie (International ed. in English); vol 59, iss 51, 23180-23187; 1433-7851
- Publication Year :
- 2020
-
Abstract
- Super-concentrated "water-in-salt" electrolytes recently spurred resurgent interest for high energy density aqueous lithium-ion batteries. Thermodynamic stabilization at high concentrations and kinetic barriers towards interfacial water electrolysis significantly expand the electrochemical stability window, facilitating high voltage aqueous cells. Herein we investigated LiTFSI/H2 O electrolyte interfacial decomposition pathways in the "water-in-salt" and "salt-in-water" regimes using synchrotron X-rays, which produce electrons at the solid/electrolyte interface to mimic reductive environments, and simultaneously probe the structure of surface films using X-ray diffraction. We observed the surface-reduction of TFSI- at super-concentration, leading to lithium fluoride interphase formation, while precipitation of the lithium hydroxide was not observed. The mechanism behind this photoelectron-induced reduction was revealed to be concentration-dependent interfacial chemistry that only occurs among closely contact ion-pairs, which constitutes the rationale behind the "water-in-salt" concept.
Details
- Database :
- OAIster
- Journal :
- Angewandte Chemie (International ed. in English); vol 59, iss 51, 23180-23187; 1433-7851
- Notes :
- application/pdf, Angewandte Chemie (International ed. in English) vol 59, iss 51, 23180-23187 1433-7851
- Publication Type :
- Electronic Resource
- Accession number :
- edsoai.on1367449645
- Document Type :
- Electronic Resource