Water-in-Salt LiTFSI Aqueous Electrolytes. 1. Liquid Structure from Combined Molecular Dynamics Simulation and Experimental Studies

• DOI: 10.1021/acs.jpcb.1c02189
• Publication Date: 2021-04-27T23:01:27Z
• Authors: Yong Zhang; Nicholas H. C. Lewis; Julian Mars; Gang Wan; Nicholas J. Weadock; Christopher J. Ta...; Maria R. Lukatskaya; Hans-Georg Steinrück; Michael F. Toney; Andrei Tokmakoff; Edward J. Maginn
• Keywords: Imide

The concept of water-in-salt electrolytes was introduced recently, and these systems have been successfully applied to yield extended operation voltage hence significantly improved energy density in aqueous Li-ion batteries. In the present work, results X-ray scattering Fourier-transform infrared spectra measurements over a wide range temperatures salt concentrations are reported for LiTFSI (lithium bis(trifluoromethane sulfonyl)imide)-based electrolyte. Classical molecular dynamics simulations validated against experiments used gain additional information about electrolyte structure. Based on our analyses, new model liquid structure is proposed. Specifically, we demonstrate that at highest concentration 20 m water network disrupted, majority molecules exist form isolated monomers, clusters, or small aggregates with chain-like configurations. On other hand, TFSI- anions connected each network. This description fundamentally different from those proposed earlier studies this system.