Liquid Structure with Nano-Heterogeneity Promotes Cationic Transport in Concentrated Electrolytes

Published

October 10, 2017

Author(s)

Oleg Borodin, Liumin Suo, Mallory Gobet, Xiaoming Ren, Fei Wang, Antonio Faraone, Jing Peng, Marco Olguin, Marshall Schroeder, Michael S. Ding, Eric Gobrogge, Arthur von Wald Cresce, Stephen Munoz, Joseph Dura, Steve Greenbaum, Chunsheng Wang, Kang Xu

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(trifluoromethane sulfonyl)imide (LiTFSI). We discovered that, at high salt concentrations (1021 mol/kg), a disproportion of cation solvation occurs, leading to a liquid structure of heterogeneous domains with a characteristic length-scale of 12 nm. This unusual nano-heterogeneity effectively decouples cations from the coulombic traps of anions, and provides a 3-D percolating Li⁺H2O network, via which 40% of Li⁺ are liberated for fast ion transport even in concentration ranges traditionally considered too viscous. Thanks to such percolation networks, super-concentrated ranges traditionally considered too viscous. Thanks to such percolation networks, super-concentrated aqueous eletrolytes are characterized by high LI⁺-transference number (0.73), which is key to supporting an assortment of battery chemistries at high rate. The in-depth understanding of this new transport mechanism establishes guiding principles to the tailor-design of future super-concentrated electrolyte systems.

Citation

ACS Nano

Volume

2017

Issue

11

Pub Type

Journals

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Keywords

electrolyte, solvation shell, molecular dynamics, Small Angle Neutron scattering, ion conductivity, ionic liquid

Citation

Borodin, O. , Suo, L. , Gobet, M. , Ren, X. , Wang, F. , Faraone, A. , Peng, J. , Olguin, M. , Schroeder, M. , Ding, M. , Gobrogge, E. , von Wald Cresce, A. , Munoz, S. , Dura, J. , Greenbaum, S. , Wang, C. and Xu, K. (2017), Liquid Structure with Nano-Heterogeneity Promotes Cationic Transport in Concentrated Electrolytes, ACS Nano, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=924000 (Accessed October 9, 2025)