Theory of ion aggregation and gelation in super-concentrated electrolytes
Name
2002.11825.pdf
Description
Submitted version
Size
2.07 MB
Format
Adobe PDF
Checksum (MD5)
724491d7682ee9623202c6bc13de152f
Author(s)
McEldrew, Michael
Goodwin, Zachary AH
Bi, Sheng
Bazant, Martin Z
Kornyshev, Alexei A
Date Issued
2020
Journal
The Journal of Chemical Physics
Publisher
AIP Publishing
Version
Original manuscript
Abstract
In concentrated electrolytes with asymmetric or irregular ions, such as ionic liquids and solvent-in-salt electrolytes, ion association is more complicated than simple ion-pairing. Large branched aggregates can form at significant concentrations at even moderate salt concentrations. When the extent of ion association reaches a certain threshold, a percolating ionic gel network can form spontaneously. Gelation is a phenomenon that is well known in polymer physics, but it is practically unstudied in concentrated electrolytes. However, despite this fact, the ion-pairing description is often applied to these systems for the sake of simplicity. In this work, drawing strongly from established theories in polymer physics, we develop a simple thermodynamic model of reversible ionic aggregation and gelation in concentrated electrolytes accounting for the competition between ion solvation and ion association. Our model describes, with the use of several phenomenological parameters, the populations of ionic clusters of different sizes as a function of salt concentration; it captures the onset of ionic gelation and also the post-gel partitioning of ions into the gel. We discuss the applicability of our model, as well as the implications of its predictions on thermodynamic, transport, and rheological properties.
MIT Department
Massachusetts Institute of Technology. Department of Chemical Engineering
Massachusetts Institute of Technology. Department of Mathematics
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Creative Commons Attribution-Noncommercial-Share Alike
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DOI of Published Version
https://doi.org/10.1063/5.0006197
