Ion clustering in molecular dynamics simulations of sodium iodide solutions

Vilia Ann Payne, Jian Hua Xu, Maria Forsyth, Mark A. Ratner, Duward F. Shriver, Simon W. de Leeuw

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Abstract

Model systems of sodium iodide dissolved in dimethyl ether or 1,2-dimethoxyethane (glyme) were studied in order to investigate the structural and dynamic properties of ionic solutions in small and polymeric ethers. Full molecular dynamics simulations were performed at a range of different salt concentrations. An algorithm was designed which assigns ions to clusters and then calculates all the terms which contribute to ionic conductivity. In dilute solutions, free ions are the most common ionic species, followed by ion pairs. As the concentration increases, pairs become the most common species, with significant concentrations of clusters with 3 through 6 ions. Changing the solvent from dimethyl ether to glyme significantly decreases the ion clustering due to the chelate effect in which the two oxygens on a solvent stabilize an associated cation. The conductivity in stable systems is shown to be primarily the result of the movement of free ions and the relative movement of ions within neutral pairs. The Nernst-Einstein relation, commonly used in the discussion of polymer electrolytes, is shown to be inadequate to quantitatively describe conductivity in the model systems.

Original languageEnglish
Pages (from-to)2087-2091
Number of pages5
JournalElectrochimica Acta
Volume40
Issue number13-14
DOIs
Publication statusPublished - Oct 1995

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Keywords

  • Nernst-Einstein equation
  • conductivity analysis
  • ion cluster
  • ion pair
  • simulation

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Electrochemistry

Cite this

Payne, V. A., Xu, J. H., Forsyth, M., Ratner, M. A., Shriver, D. F., & de Leeuw, S. W. (1995). Ion clustering in molecular dynamics simulations of sodium iodide solutions. Electrochimica Acta, 40(13-14), 2087-2091. https://doi.org/10.1016/0013-4686(95)00145-5