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Towards Higher Energy Density Redox‐Flow Batteries: Imidazolium Ionic Liquid for Zn Electrochemistry in Flow Environment
Author(s) -
Periyapperuma Kalani,
Zhang Yafei,
MacFarlane Douglas R.,
Forsyth Maria,
PozoGonzalo Cristina,
Howlett Patrick C.
Publication year - 2017
Publication title -
chemelectrochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.182
H-Index - 59
ISSN - 2196-0216
DOI - 10.1002/celc.201600875
Subject(s) - ionic liquid , electrochemistry , redox , flow (mathematics) , energy density , chemical engineering , electrochemical energy storage , materials science , inorganic chemistry , chemistry , electrode , engineering physics , catalysis , supercapacitor , organic chemistry , mechanics , physics , engineering
We present the first demonstration of an ionic liquid electrolyte under a realistic flow environment for applications in redox‐flow batteries based on the Zn 2+ /Zn 0 redox couple. An electrolyte mixture containing Zn(dca) 2 and 3 wt % H 2 O in 1‐ethyl‐3‐methylimidazolium dicyanamide, [Emim][dca], ionic liquid was used to study the effects of Zn 2+ concentration and flow rate on the Zn 2+ /Zn 0 electrochemical performance as well as its impact on the morphology of the Zn deposit. An optimized Zn 2+ 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 (18 mol %) showed favourable results; voltammetry showed higher peak current densities (100 mA/cm 2 discharge current density) and more positive Zn electrodeposition potentials (−1.33 V vs Ag/AgOTf) coupled with higher cycling efficiency (45±3%) compared to those obtained with the lower Zn concentration system (9 mol %, −1.44 V vs Ag/AgOTf, 48 mA/cm 2 discharge current density and 33±3% cycling efficiency).