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arXiv · 2512.18167

Dehydration-Driven Ion Aggregation and the Onset of Gelation in ZnCl$_2$ Solution

Alexei V. Tkachenko·Chuntian Cao·Amy C. Marschilok·Deyu Lu
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Abstract

A minimal model of ionic aggregation in concentrated ZnCl$_2$ is developed, guided by molecular dynamics simulations with a machine-learned potential. It explicitly incorporates solvent-site depletion, correlated chloride binding, and allows for loops within Zn-Cl clusters. Dehydration is shown to drive ion binding through two sharp transitions set by the Zn coordination number $Z$: a crossover at $Z=2$ from isolated ions to Cl-bridged clusters, and gelation near $Z\approx 3$. The model agrees quantitatively with MD results, and the critical exponent of the cluster-size distribution matches percolation theory.

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Alexei V. Tkachenko, Chuntian Cao, Amy C. Marschilok, Deyu Lu. 2025-12-20. Dehydration-Driven Ion Aggregation and the Onset of Gelation in ZnCl$_2$ Solution. https://doi.org/10.1103/gxkq-6zw4

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