Imidazolium Triflate Ionic Liquids’ Capacitance–Potential Relationships and Transport Properties Affected by Cation Chain Lengths

Niroodha R Pitawela; Scott K Shaw

doi:10.1021/acsmeasuresciau.1c00015

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Imidazolium Triflate Ionic Liquids’ Capacitance–Potential Relationships and Transport Properties Affected by Cation Chain Lengths

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Imidazolium Triflate Ionic Liquids’ Capacitance–Potential Relationships and Transport Properties Affected by Cation Chain Lengths

Niroodha R Pitawela and Scott K Shaw

ACS Measurement Science Au, Vol.1(3), pp.117-130

12/15/2021

DOI: 10.1021/acsmeasuresciau.1c00015

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Abstract

In this paper we report the effects of five imidazolium cations with varying alkyl chain lengths to study the effects of cation size on capacitance versus voltage behavior. The cations include ethyl-, butyl-, hexyl-, octyl-, and decyl-3-methylimidazolium, all paired with a triflate anion. We analyze the capacitance with respect to the cation alkyl chain length qualitatively and quantitatively by analyzing changes in the capacitance–potential curvature shape and magnitude across several standard scanning protocols and electrochemical techniques. Further, three transport properties (viscosity, diffusion coefficient, and electrical conductivity) are experimentally determined and integrated into the outcomes. Ultimately, we find higher viscosities, lower diffusion coefficients, and lower electrical conductivities when the alkyl chain length is increased. Also, capacitance values increase with cation size, except 1-octyl-3-methylimidazolium, which does not follow an otherwise linear trend. This capacitive increase is most pronounced when sweeping the potential in the cathodic direction. These findings challenge the conventional hypothesis that increasing the length of the alkyl chain of imidazolium cations diminishes the capacitance and ionic liquid performance in charge storage.

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Title: Subtitle: Imidazolium Triflate Ionic Liquids’ Capacitance–Potential Relationships and Transport Properties Affected by Cation Chain Lengths
Creators: Niroodha R Pitawela - Department of Chemistry, University of Iowa, Iowa City, Iowa 52242, United States
Scott K Shaw - Department of Chemistry, University of Iowa, Iowa City, Iowa 52242, United States
Resource Type: Journal article
Publication Details: ACS Measurement Science Au, Vol.1(3), pp.117-130
DOI: 10.1021/acsmeasuresciau.1c00015
ISSN: 2694-250X
eISSN: 2694-250X
Publisher: American Chemical Society
Language: English
Date published: 12/15/2021
Academic Unit: Chemistry
Record Identifier: 9984217549802771

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