The electrical double layer of dicationic ionic liquids at onion-like carbon surface

Song Li; Katherine L. Van Aken; John K. McDonough; Guang Feng; Yury Gogotsi; Peter T. Cummings

doi:10.1021/jp409888f

The electrical double layer of dicationic ionic liquids at onion-like carbon surface

Song Li^*, Katherine L. Van Aken, John K. McDonough, Guang Feng^*, Yury Gogotsi, Peter T. Cummings

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

52 Citations (Scopus)

Abstract

The electrical double layer (EDL) structure formed by ions at a charged surface, which is the key to determining the performance of supercapacitors, has been extensively studied for many monocationic ionic liquids (MILs). However, it is not known what effect replacing MILs with dicationic ionic liquids (DILs) will have on the EDL structure. In this work, the interfacial structure and electrochemical performance of DILs [C_n(mim)₂](BF ₄)₂ (n = 3, 6, 9) and [C₆(mim) ₂](Tf₂N)₂ were investigated using classical molecular dynamics (MD) simulation for comparison with their monocationic counterparts. Different EDL structures formed by DILs and MILs near an onion-like carbon (OLC) electrode were observed. The interfacial orientation of the imidazolium plane in dications was verified to be similar to that of monocations. Moreover, the dissimilar sizes of the cation/anion and the specific ion adsorption on OLC were found to contribute to the distinctive shape of the differential capacitance-electric potential (C-V) curves, which were also dependent on the type of anions. Increased capacitance in BF₄- containing DILs was not observed in comparison with their counterpart MILs, whereas dicationic [C₆(mim)₂](Tf₂N)₂ yielded higher differential capacitance in contrast to monocationic [C ₆mim][Tf₂N], which was substantiated by cyclic voltammetry measurements as well. This work provides molecular insights into the EDL structure and C-V curves of imidazolium-based DILs in OLC-based supercapacitors.

Original language	English
Pages (from-to)	3901-3909
Number of pages	9
Journal	Journal of Physical Chemistry C
Volume	118
Issue number	8
DOIs	https://doi.org/10.1021/jp409888f
Publication status	Published - 27 Feb 2014

Keywords

Anions
Cations
Electric Properties
Electrodes
Ions

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials
General Energy
Physical and Theoretical Chemistry
Surfaces, Coatings and Films

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10.1021/jp409888f

Cite this

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title = "The electrical double layer of dicationic ionic liquids at onion-like carbon surface",

abstract = "The electrical double layer (EDL) structure formed by ions at a charged surface, which is the key to determining the performance of supercapacitors, has been extensively studied for many monocationic ionic liquids (MILs). However, it is not known what effect replacing MILs with dicationic ionic liquids (DILs) will have on the EDL structure. In this work, the interfacial structure and electrochemical performance of DILs [Cn(mim)2](BF 4)2 (n = 3, 6, 9) and [C6(mim) 2](Tf2N)2 were investigated using classical molecular dynamics (MD) simulation for comparison with their monocationic counterparts. Different EDL structures formed by DILs and MILs near an onion-like carbon (OLC) electrode were observed. The interfacial orientation of the imidazolium plane in dications was verified to be similar to that of monocations. Moreover, the dissimilar sizes of the cation/anion and the specific ion adsorption on OLC were found to contribute to the distinctive shape of the differential capacitance-electric potential (C-V) curves, which were also dependent on the type of anions. Increased capacitance in BF4- containing DILs was not observed in comparison with their counterpart MILs, whereas dicationic [C6(mim)2](Tf2N)2 yielded higher differential capacitance in contrast to monocationic [C 6mim][Tf2N], which was substantiated by cyclic voltammetry measurements as well. This work provides molecular insights into the EDL structure and C-V curves of imidazolium-based DILs in OLC-based supercapacitors.",

keywords = "Anions, Cations, Electric Properties, Electrodes, Ions",

author = "Song Li and \{Van Aken\}, \{Katherine L.\} and McDonough, \{John K.\} and Guang Feng and Yury Gogotsi and Cummings, \{Peter T.\}",

year = "2014",

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doi = "10.1021/jp409888f",

language = "English",

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journal = "Journal of Physical Chemistry C",

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T1 - The electrical double layer of dicationic ionic liquids at onion-like carbon surface

AU - Li, Song

AU - Van Aken, Katherine L.

AU - McDonough, John K.

AU - Feng, Guang

AU - Gogotsi, Yury

AU - Cummings, Peter T.

PY - 2014/2/27

Y1 - 2014/2/27

N2 - The electrical double layer (EDL) structure formed by ions at a charged surface, which is the key to determining the performance of supercapacitors, has been extensively studied for many monocationic ionic liquids (MILs). However, it is not known what effect replacing MILs with dicationic ionic liquids (DILs) will have on the EDL structure. In this work, the interfacial structure and electrochemical performance of DILs [Cn(mim)2](BF 4)2 (n = 3, 6, 9) and [C6(mim) 2](Tf2N)2 were investigated using classical molecular dynamics (MD) simulation for comparison with their monocationic counterparts. Different EDL structures formed by DILs and MILs near an onion-like carbon (OLC) electrode were observed. The interfacial orientation of the imidazolium plane in dications was verified to be similar to that of monocations. Moreover, the dissimilar sizes of the cation/anion and the specific ion adsorption on OLC were found to contribute to the distinctive shape of the differential capacitance-electric potential (C-V) curves, which were also dependent on the type of anions. Increased capacitance in BF4- containing DILs was not observed in comparison with their counterpart MILs, whereas dicationic [C6(mim)2](Tf2N)2 yielded higher differential capacitance in contrast to monocationic [C 6mim][Tf2N], which was substantiated by cyclic voltammetry measurements as well. This work provides molecular insights into the EDL structure and C-V curves of imidazolium-based DILs in OLC-based supercapacitors.

AB - The electrical double layer (EDL) structure formed by ions at a charged surface, which is the key to determining the performance of supercapacitors, has been extensively studied for many monocationic ionic liquids (MILs). However, it is not known what effect replacing MILs with dicationic ionic liquids (DILs) will have on the EDL structure. In this work, the interfacial structure and electrochemical performance of DILs [Cn(mim)2](BF 4)2 (n = 3, 6, 9) and [C6(mim) 2](Tf2N)2 were investigated using classical molecular dynamics (MD) simulation for comparison with their monocationic counterparts. Different EDL structures formed by DILs and MILs near an onion-like carbon (OLC) electrode were observed. The interfacial orientation of the imidazolium plane in dications was verified to be similar to that of monocations. Moreover, the dissimilar sizes of the cation/anion and the specific ion adsorption on OLC were found to contribute to the distinctive shape of the differential capacitance-electric potential (C-V) curves, which were also dependent on the type of anions. Increased capacitance in BF4- containing DILs was not observed in comparison with their counterpart MILs, whereas dicationic [C6(mim)2](Tf2N)2 yielded higher differential capacitance in contrast to monocationic [C 6mim][Tf2N], which was substantiated by cyclic voltammetry measurements as well. This work provides molecular insights into the EDL structure and C-V curves of imidazolium-based DILs in OLC-based supercapacitors.

KW - Anions

KW - Cations

KW - Electric Properties

KW - Electrodes

KW - Ions

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SN - 1932-7447

VL - 118

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JO - Journal of Physical Chemistry C

JF - Journal of Physical Chemistry C

IS - 8

ER -

The electrical double layer of dicationic ionic liquids at onion-like carbon surface

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