Stable zinc cycling in novel alkoxy-ammonium based ionic liquid electrolytes

Mega Kar, Bjorn Winther-Jensen, Michel Armand, Tristan Simons, Orawan Winther-Jensen, Maria Forsyth, Douglas Macfarlane

Research output: Contribution to journalArticleResearchpeer-review

29 Citations (Scopus)

Abstract

High-energy density Zinc-air batteries are currently of interest since they could play a key role in emerging large-scale energy storage applications. However, achieving good rechargeability of such metal-air batteries requires significant further research and development effort. Room Temperature Ionic liquids (RTILs) offer a number of ideal thermal and physical properties as potential electrolytes for large-scale energy storage applications and thus, can help increase the practicality of such electrochemical devices. This paper reports the synthesis and application of three novel quaternary alkoxy ammonium bis(trifluoromethylsulfonyl)amide based RTILs, with two or more ether functional groups designed to interact and solubilize zinc ions, in order to aid in the electrochemical reversibility of the metal. The anion is successfully reduced from, and re-oxidized into, the three alkoxy ammonium RTILs suggesting that they are potential candidates as electrolytes for use in zinc-air batteries. Cyclic voltammetry reveals that the presence of water reduces the activation barrier required to deposit zinc and assists stable charge/discharge cycling in an electrolyte consisting of 0.1 M Zn(NTf2)2 in the tri-alkoxy ammonium chain RTIL, [N2(20201)(20201)(20201)] [NTf2], with 2.5 wt.% H2O. Further experiments demonstrate that with such electrolyte a Zn electrode can complete at least 750 cycles at a current density of 0.1 mA/cm2 at room temperature.

Original languageEnglish
Pages (from-to)461-471
Number of pages11
JournalElectrochimica Acta
Volume188
DOIs
Publication statusPublished - 10 Jan 2016

Keywords

  • batteries
  • ionic liquids
  • metal-air
  • zinc

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