Competitive Salt Precipitation/Dissolution During Free‐Water Reduction in Water‐in‐Salt Electrolyte
Year: 2020
Type: article
Abstract: Water-in-salt electrolytes based on highly concentrated bis(trifluoromethyl)sulfonimide (TFSI) promise aqueous electrolytes with stabilities nearing 3 V. However, especially with an electrode approaching the cathodic (reductive) stability, cycling stability is insufficient. While stability critically relies on a solid electrolyte interphase (SEI), the mechanism behind the cathodic stability limit remains unclear. Now, two distinct reduction potentials are revealed for the chemical environments of free and bound water and that both contribute to SEI formation. Free water is reduced about 1 V above bound water in a hydrogen evolution reaction (HER) and is responsible for SEI formation via reactive intermediates of the HER; concurrent LiTFSI precipitation/dissolution establishes a dynamic interface. The free-water population emerges, therefore, as the handle to extend the cathodic limit of aqueous electrolytes and the battery cycling stability.
Institutions: Centre National de la Recherche Scientifique, Université de Montpellier, Réseau sur le Stockage Electrochimique de l'énergie, Institut Charles Gerhardt Montpellier, Commissariat à l'Énergie Atomique et aux Énergies Alternatives, Université Paris-Saclay, Sorbonne Université, Maison de la Simulation, CEA Paris-Saclay, PHENIX laboratory, Institute of Science and Technology Austria, Graz University of Technology
Language: English
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $4,314
Awards: G1960253346, G212572087, G2356717574, Laboratory of excellency for electrochemical energy storage, G3010527862, Organic Mixed Ion and Electron Conductors for High-Energy Batteries, Accounting for Metallicity, Polarization of the Electrolyte, and Redox reactions in computational Electrochemistry, G7240651115, Batteries relying on Lithium-based Water-In-Salt Electrolytes
OpenAlex ID: W3020848751