Structure and dynamics of highly concentrated LiTFSI/acetonitrile electrolytes
Artikel i vetenskaplig tidskrift, 2021

High salt concentration has been shown to induce increased electrochemical stability in organic solvent-based electrolytes. Accompanying the change in bulk properties is a structural ordering on mesoscopic length scales and changes in the ion transport mechanism have also been suggested. Here we investigate the local structure and dynamics in highly concentrated acetonitrile electrolytes as a function of salt concentration. Already at low concentrations ordering on microscopic length scales in the electrolytes is revealed by small angle X-ray scattering, as a result of correlations of Li+ coordinating clusters. For higher salt concentrations a charge alternation-like ordering is found as anions start to take part in the solvation. Results from quasi-elastic neutron spectroscopy reveal a jump diffusion dynamical process with jump lengths virtually independent of both temperature and Li-salt concentration. The jump can be envisaged as dissociation of a solvent molecule or anion from a particular Li+ solvation structure. The residence time, 50-800 ps, between the jumps is found to be highly temperature and Li-salt concentration dependent, with shorter residence times for higher temperature and lower concentrations. The increased residence time at high Li-salt concentration can be attributed to changes in the interaction of the solvation shell as a larger fraction of TFSI anions take part in the solvation, forming more stable solvation shells.

Författare

Filippa Lundin

Chalmers, Fysik, Materialfysik

Luis Aguilera Medina

Volvo Cars

Kondenserade materiens fysik

Henriette Wase Hansen

Kondenserade materiens fysik

Roskilde Universitet (RUC)

Institut Laue-Langevin

Sebastian Lages

Max IV-laboratoriet

Chalmers, Fysik, Materialfysik

Ana Labrador

Max IV-laboratoriet

Kristine Niss

Roskilde Universitet (RUC)

Bernhard Frick

Institut Laue-Langevin

Aleksandar Matic

Chalmers, Fysik, Materialfysik

Physical Chemistry Chemical Physics

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

Vol. In Press

Sveriges Neutronforskarskola - SwedNESS

Stiftelsen för Strategisk forskning (SSF) (GSn15-0008), 2017-01-01 -- 2020-12-31.

Stiftelsen för Strategisk forskning (SSF) (GSn15-0008), 2016-07-01 -- 2021-06-30.

Ämneskategorier

Oorganisk kemi

Fysikalisk kemi

Teoretisk kemi

DOI

10.1039/d1cp02006d

Mer information

Senast uppdaterat

2021-07-06