Reversible Zinc Electrodeposition at −60 °C Using a Deep Eutectic Electrolyte for Low-Temperature Zinc Metal Batteries

Brendan E. Hawkins, Theresa Schoetz, Leo W. Gordon, Surabh Kt, Jonah Wang, Robert J. Messinger

Research output: Contribution to journalArticlepeer-review

Abstract

Rechargeable zinc (Zn) metal batteries are attractive for use as electrochemical energy storage systems on a global scale because of the low cost, high energy density, inherent safety, and strategic resource security of Zn metal. However, at low temperatures, Zn batteries typically suffer from high electrolyte viscosity and unfavorable ion transport properties. Here, we studied reversible Zn electrodeposition in mixtures of 1-ethyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide ([EMIm]TFSI) ionic liquid, γ-butyrolactone (GBL) organic solvent, and Zn(TFSI)2 zinc salt. The electrolyte mixtures enabled reversible Zn electrodeposition at temperatures as low as −60 °C. An electrolyte composed of 0.1 M Zn(TFSI)2 in [EMIm]TFSI:GBL with a volume ratio of 1:3 formed a deep eutectic solvent that optimized electrolyte conductivity, viscosity, and the zinc diffusion coefficient. Liquid-state 1H and 13C nuclear magnetic resonance (NMR) spectroscopy and molecular dynamic (MD) simulations indicate increased formation of contact ion pairs and the reduction of ion aggregates are responsible for the optimal composition.

Original languageEnglish (US)
Pages (from-to)2378-2386
Number of pages9
JournalJournal of Physical Chemistry Letters
Volume14
Issue number9
DOIs
StatePublished - Mar 9 2023
Externally publishedYes

ASJC Scopus subject areas

  • Materials Science(all)
  • Physical and Theoretical Chemistry

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