Ion Transport Mechanisms via Time-Dependent Local Structure and Dynamics in Highly Concentrated Electrolytes
Journal article, 2020

Highly concentrated electrolytes (HCEs) are attracting interest as safer and more stable alternatives to current lithium-ion battery electrolytes, but their structure, solvation dynamics and ion transport mechanisms are arguably more complex. We here present a novel general method for analyzing both the structure and the dynamics, and ultimately the ion transport mechanism(s), of electrolytes including HCEs. This is based on automated detection of bonds, both covalent and coordination bonds, including how they dynamically change, in molecular dynamics (MD) simulation trajectories. We thereafter classify distinct local structures by their bond topology and characterize their physicochemical properties by statistical mechanics, giving both a qualitative and quantitative description of the structure, solvation and coordination dynamics, and ion transport mechanism(s). We demonstrate the method by in detail analyzing an ab initio MD simulation trajectory of an HCE consisting of the LiTFSI salt dissolved in acetonitrile at a 1:2 molar ratio. We find this electrolyte to form a flexible percolating network which limits vehicular ion transport but enables the Li+ ions to move between different TFSI coordination sites along with their first solvation shells. In contrast, the TFSI anions are immobilized in the network, but often free to rotate which further facilitates the Li+ hopping mechanism.

molecular dynamics

Lithium-ion batteries

highly concentrated electrolytes

ion transport mechanisms


Rasmus Andersson

Chalmers, Physics, Materials Physics

Fabian Årén

Chalmers, Physics, Materials Physics

Alejandro A. Franco

Alistore - European Research Institute

Institut Universitaire de France

Research network on electrochemical energy storage

University of Picardie Jules Verne

Patrik Johansson

Institut Universitaire de France

Chalmers, Physics, Materials Physics

Journal of the Electrochemical Society

0013-4651 (ISSN) 1945-7111 (eISSN)

Vol. 167 14 140537

Driving Forces

Sustainable development

Innovation and entrepreneurship

Areas of Advance



Materials Science

Subject Categories

Physical Chemistry

Physical Sciences

Condensed Matter Physics


Basic sciences


C3SE (Chalmers Centre for Computational Science and Engineering)



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