Towards higher energy density redox-flow batteries: imidazolium ionic liquid for Zn electrochemistry in flow environment

Kalani Periyapperuma, Yafei Zhang, Douglas R. Macfarlane, Maria Forsyth, Cristina Pozo-Gonzalo, Patrick C Howlett

Research output: Contribution to journalArticleResearchpeer-review

7 Citations (Scopus)

Abstract

We present the first demonstration of an ionic liquid electrolyte under a realistic flow environment for applications in redox-flow batteries based on the Zn2+/Zn0 redox couple. An electrolyte mixture containing Zn(dca)2 and 3wt% H2O in 1-ethyl-3-methylimidazolium dicyanamide, [Emim][dca], ionic liquid was used to study the effects of Zn2+ concentration and flow rate on the Zn2+/Zn0 electrochemical performance as well as its impact on the morphology of the Zn deposit. An optimized Zn2+ concentration and flow rate were determined by using an in-house-designed 3D-printed flow-cell prototype. Surface characterization through SEM revealed that both the concentration and flow rate directly impact Zn morphology under flow conditions. The electrolyte mixture with a higher Zn(dca)2 concentration (18mol%) showed favourable results; voltammetry showed higher peak current densities (100mA/cm2 discharge current density) and more positive Zn electrodeposition potentials (-1.33V vs Ag/AgOTf) coupled with higher cycling efficiency (45±3%) compared to those obtained with the lower Zn concentration system (9mol%, -1.44V vs Ag/AgOTf, 48mA/cm2 discharge current density and 33±3% cycling efficiency).

Original languageEnglish
Pages (from-to)1051-1058
Number of pages9
JournalChemElectroChem
Volume4
Issue number5
DOIs
Publication statusPublished - May 2017

Keywords

  • Flow conditions
  • Flow rate
  • Morphology
  • Redox flow
  • Zinc

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