Volume 246, 2023

A screening of results on the decay length in concentrated electrolytes

Abstract

Screening of electrostatic interactions in room-temperature ionic liquids and concentrated electrolytes has recently attracted much attention as surface force balance experiments have suggested the emergence of unanticipated anomalously large screening lengths at high ion concentrations. Termed underscreening, this effect was ascribed to the bulk properties of concentrated ionic systems. However, underscreening under experimentally relevant conditions is not predicted by classical theories and challenges our understanding of electrostatic correlations. Despite the enormous effort in performing large-scale simulations and new theoretical investigations, the origin of the anomalously long-range screening length remains elusive. This contribution briefly summarises the experimental, analytical and simulation results on ionic screening and the scaling behaviour of screening lengths. We then present an atomistic simulation approach that accounts for the solvent and ion exchange with a reservoir. We find that classical density functional theory (DFT) for concentrated electrolytes under confinement reproduces ion adsorption at charged interfaces surprisingly well. With DFT, we study confined electrolytes using implicit and explicit solvent models and the dependence on the solvent's dielectric properties. Our results demonstrate how the absence vs. presence of solvent particles and their discrete nature affect the short and long-range screening in concentrated ionic systems.

Graphical abstract: A screening of results on the decay length in concentrated electrolytes

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Article information

Article type
Paper
Submitted
17 Feb 2023
Accepted
27 Apr 2023
First published
21 Aug 2023
This article is Open Access
Creative Commons BY license

Faraday Discuss., 2023,246, 520-539

A screening of results on the decay length in concentrated electrolytes

H. Jäger, A. Schlaich, J. Yang, C. Lian, S. Kondrat and C. Holm, Faraday Discuss., 2023, 246, 520 DOI: 10.1039/D3FD00043E

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