Ion interactions and dynamics in pseudohalide based ionic liquid electrolytes containing sodium solutes

Matthias Hilder, Tony Pointu, Haijin Zhu, Michel Armand, Patrick Howlett, Maria Forsyth*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

Sodium batteries have been identified as a promising, inexpensive technology for future energy storage applications. However, while an optimum electrolyte is key to a high performance device, sodium electrolytes are still at an early stage of development. Recently we explored the cycling behavior of a series of electrolytes based on a readily available dicyanamide-based ionic liquid with various sodium salts added based on fluorinated anions in order to improve sodium electrochemistry. Herein we focus on the structure and ion dynamics in the bulk electrolyte. Electrolyte solutions of 1-methyl,1-propyl pyrrolidinium dicyanamide (C3mpyDCA) and 1-methyl,1-butyl pyrrolidinium tricyanomethanide (C4mpyTCM) with various sodium salts were studied in order to understand the effect of solute anion on physicochemical behavior, in particular phase behavior, ion dynamics and inter-ionic interactions. For the DCA systems strong Na+-DCA interactions dominate. The expectation that switching to the TCM anion would see a weakening in the electrostatic interactions (due to a higher degree of charge delocalization and larger size ion) was not observed. Indeed the TCM systems led to less salt solubility, lower ionic conductivity and greater deviation from the Walden ideal KCl line. We use infrared and NMR spectroscopies to investigate ion-ion interactions and it appears that the nitrile anion dominates the Na coordination environment for both DCA and TCM ionic liquid systems.

Original languageEnglish
Article number112597
JournalJournal of Molecular Liquids
Volume303
DOIs
StatePublished - 1 Apr 2020
Externally publishedYes

Keywords

  • DCA
  • Electrolytes
  • Energy storage
  • Intermolecular interactions
  • Ionic liquids
  • Sodium batteries
  • TCM

Fingerprint

Dive into the research topics of 'Ion interactions and dynamics in pseudohalide based ionic liquid electrolytes containing sodium solutes'. Together they form a unique fingerprint.

Cite this