Molecular Dynamics Analysis of Charge Transport in Ionic-Liquid Electrolytes Containing Added Salt with Mono, Di, and Trivalent Metal Cations

José Manuel Vicent-Luna, Eneko Azaceta, Said Hamad, José Manuel Ortiz-Roldán, Ramón Tena-Zaera, Sofía Calero, Juan Antonio Anta (Corresponding author)

Research output: Contribution to journalArticleAcademicpeer-review

13 Citations (Scopus)

Abstract

Among many other applications, room-temperature ionic liquids (ILs) are used as electrolytes for storage and energy-conversion devices. In this work, we investigate, at the microscopic level, the structural and dynamical properties of 1-methyl-1-butyl-pyrrolidinium bis(trifluoromethanesulfonyl) imide [C4PYR]+[Tf2N] IL-based electrolytes for metal-ion batteries. We carried out molecular dynamics simulations of electrolytes mainly composed of [C4PYR]+[Tf2N] IL with the addition of Mn+-[Tf2N] metal salts (M=Li+, Na+, Ni2+, Zn2+, Co2+, Cd2+, and Al3+, n=1, 2, and 3) dissolved in the IL. The addition of low salt concentrations lowers the charge transport and conductivity of the electrolytes. This effect is due to the strong interaction of the metal cations with the [Tf2N] anions, which allows for molecular aggregation between them. We analyze how the conformation of the [Tf2N] anions surrounding the metal cations determine the charge-transport properties of the electrolyte. We found two main conformations based on the size and charge of the metal cation: monodentate and bidentate (number of oxygen atoms of the anion pointing to the metal atoms). The microscopic local structure of the Mn+-[Tf2N] aggregates influences the microscopic charge transport as well as the macroscopic conductivity of the total electrolyte.

Original languageEnglish
Pages (from-to)1665-1673
Number of pages9
JournalChemPhysChem
Volume19
Issue number13
DOIs
Publication statusPublished - 5 Jul 2018
Externally publishedYes

Keywords

  • ion solvation
  • ionic conductivity
  • metal batteries
  • pyrrolidinium
  • self-diffusion

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