1. Liquid Structure with Nano-Heterogeneity Promotes Cationic Transport in Concentrated Electrolytes.
- Author
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Borodin O, Suo L, Gobet M, Ren X, Wang F, Faraone A, Peng J, Olguin M, Schroeder M, Ding MS, Gobrogge E, von Wald Cresce A, Munoz S, Dura JA, Greenbaum S, Wang C, and Xu K
- Subjects
- Cations chemistry, Ion Transport, Molecular Structure, Neutron Diffraction, Scattering, Small Angle, Spectroscopy, Fourier Transform Infrared, Electrolytes chemistry, Hydrocarbons, Fluorinated chemistry, Imides chemistry, Lithium chemistry, Molecular Dynamics Simulation, Nanoparticles chemistry
- Abstract
Using molecular dynamics simulations, small-angle neutron scattering, and a variety of spectroscopic techniques, we evaluated the ion solvation and transport behaviors in aqueous electrolytes containing bis(trifluoromethanesulfonyl)imide. We discovered that, at high salt concentrations (from 10 to 21 mol/kg), a disproportion of cation solvation occurs, leading to a liquid structure of heterogeneous domains with a characteristic length scale of 1 to 2 nm. This unusual nano-heterogeneity effectively decouples cations from the Coulombic traps of anions and provides a 3D percolating lithium-water network, via which 40% of the lithium cations are liberated for fast ion transport even in concentration ranges traditionally considered too viscous. Due to such percolation networks, superconcentrated aqueous electrolytes are characterized by a high lithium-transference number (0.73), which is key to supporting an assortment of battery chemistries at high rate. The in-depth understanding of this transport mechanism establishes guiding principles to the tailored design of future superconcentrated electrolyte systems.
- Published
- 2017
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