Ion-ion and ion-solvent interactions in lithium imidazolide electrolytes studied by Raman spectroscopy and DFT models
Journal article, 2011

Molecular level interactions are of crucial importance for the transport properties and overall performance of ion conducting electrolytes. In this work we explore ion-ion and ion-solvent interactions in liquid and solid polymer electrolytes of lithium 4,5-dicyano-(2-trifluoromethyl)imidazolide (LiTDI)-a promising salt for lithium battery applications-using Raman spectroscopy and density functional theory calculations. High concentrations of ion associates are found in LiTDI: acetonitrile electrolytes, the vibrational signatures of which are transferable to PEO-based LiTDI electrolytes. The origins of the spectroscopic changes are interpreted by comparing experimental spectra with simulated Raman spectra of model structures. Simple ion pair models in vacuum identify the imidazole nitrogen atom of the TDI anion to be the most important coordination site for Li+, however, including implicit or explicit solvent effects lead to qualitative changes in the coordination geometry and improved correlation of experimental and simulated Raman spectra. To model larger aggregates, solvent effects are found to be crucial, and we finally suggest possible triplet and dimer ionic structures in the investigated electrolytes. In addition, the effects of introducing water into the electrolytes-via a hydrate form of LiTDI-are discussed.

aprotic-solvents

poly(ethylene oxide)

magnetic-resonance

molecular-orbital calculations

ab-initio calculations

salts

polymer

electrolytes

acetonitrile

aqueous-solutions

li+ ion

Author

Johan Scheers

Chalmers, Applied Physics, Condensed Matter Physics

L. Niedzicki

Politechnika Warszawska

Alistore - European Research Institute

G. Z. Zukowska

Politechnika Warszawska

Alistore - European Research Institute

Patrik Johansson

Chalmers, Applied Physics, Condensed Matter Physics

W. Wieczorek

Politechnika Warszawska

Alistore - European Research Institute

Per Jacobsson

Chalmers, Applied Physics, Condensed Matter Physics

Physical Chemistry Chemical Physics

1463-9076 (ISSN) 1463-9084 (eISSN)

Vol. 13 23 11136-11147

Driving Forces

Sustainable development

Subject Categories

Physical Sciences

Areas of Advance

Energy

Materials Science

DOI

10.1039/c1cp20063a

More information

Latest update

9/6/2018 2