Issue 25, 2017

Ionic liquids containing tricyanomethanide anions: physicochemical characterisation and performance as electrochemical double-layer capacitor electrolytes

Abstract

We investigated the use of fluorine free ionic liquids (ILs) containing the tricyanomethanide anion ([C(CN)3]) as an electrolyte in electrochemical double-layer capacitors (EDLCs). Three cations were used; 1-butyl-3-methylimidazolium ([Im1,4]), N-butyl-N-methylpyrrolidinium ([Pyr1,4]) and N-butyl-N-methylpiperidinium ([Pip1,4]). Their physicochemical properties are discussed alongside with their performance as electrolytes. We found that the cyano-based ILs present higher ionic conductivity (9.4, 8.7 and 4.2 mS cm−1 at 25 °C for [Im1,4], [Pyr1,4] and [Pip1,4], respectively) than the widely studied IL containing the bis(trifluoromethylsulfonyl)imide anion, namely [Pyr1,4][Tf2N] (2.7 mS cm−1 at 25 °C). Of the three ILs investigated, [Pip1,4][C(CN)3] presents the widest electrochemical stability window, 3.0 V, while [Pyr1,4][C(CN)3] is stable up to 2.9 V and its [Tf2N] analogue can operate at 3.5 V. Despite operating at a lower voltage, [Pyr1,4][C(CN)3] EDLC is capable of delivering up to 4.5 W h kg−1 when operating at high specific power of 7.2 kW kg−1, while its [Pyr1,4][Tf2N] counterpart only delivered 3.0 W h kg−1 when operated at similar power.

Graphical abstract: Ionic liquids containing tricyanomethanide anions: physicochemical characterisation and performance as electrochemical double-layer capacitor electrolytes

Supplementary files

Article information

Article type
Paper
Submitted
19 Mai 2017
Accepted
08 Jun 2017
First published
19 Jun 2017
This article is Open Access
Creative Commons BY license

Phys. Chem. Chem. Phys., 2017,19, 16867-16874

Ionic liquids containing tricyanomethanide anions: physicochemical characterisation and performance as electrochemical double-layer capacitor electrolytes

V. L. Martins, A. J. R. Rennie, R. M. Torresi and P. J. Hall, Phys. Chem. Chem. Phys., 2017, 19, 16867 DOI: 10.1039/C7CP03377J

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