Ionic liquids are considered promising electrolytes for developing electric double-layer capacitors (EDLCs) with high energy density. To identify optimal operating conditions, we performed molecular dynamics simulations of N-methyl-N-propyl pyrrolidinium bis(trifluoromethanesulfonyl)imide (mppy+ TFSI) ionic liquid confined in the interstices of vertically aligned carbon nanostructures mimicking the electrode structure. We modeled various surface charge densities as well as varied the distance between nanotubes in the array. Our results indicate that high-density ion storage occurs within the noninteracting double-layer region formed in the nanoconfined domain between charged nanotubes. We determined the specific arrangement of these ions relative to the nanotube surface and related the layered configuration to the molecular structure of the ions. The pitch distance of the nanotube array that enables optimal mppy+ TFSI storage and enhanced capacitance is determined to be 16 Å.

References

1.
Burke
,
A.
,
2000
, “
Ultracapacitors: Why, How, and Where Is the Technology
,”
J. Power Sources
,
91
(
1
), pp.
37
50
.
2.
Liu
,
C.
,
Li
,
F.
,
Ma
,
L. P.
, and
Cheng
,
H. M.
,
2010
, “
Advanced Materials for Energy Storage
,”
Adv. Mater.
,
22
(
8
), pp.
E28
E62
.
3.
Tarascon
,
J. M.
, and
Armand
,
M.
,
2001
, “
Issues and Challenges Facing Rechargeable Lithium Batteries
,”
Nature
,
414
(
6861
), pp.
359
367
.
4.
Meyyappan
,
M.
,
2013
, “
Nanostructured Materials for Supercapacitors
,”
J. Vac. Sci. Technol., A
,
31
(
5
), p.
050803
.
5.
Winter
,
M.
, and
Brodd
,
R. J.
,
2004
, “
What Are Batteries, Fuel Cells, and Supercapacitors?
,”
Chem. Rev.
,
104
(
10
), pp.
4245
4269
.
6.
Feng
,
G.
,
Li
,
S.
,
Atchison
,
J. S.
,
Presser
,
V.
, and
Cummings
,
P. T.
,
2013
, “
Molecular Insights Into Carbon Nanotube Supercapacitors: Capacitance Independent of Voltage and Temperature
,”
J. Phys. Chem. C
,
117
(
18
), pp.
9178
9186
.
7.
Aslan
,
M.
,
Weingarth
,
D.
,
Jaeckel
,
N.
,
Atchison
,
J. S.
,
Grobelsek
,
I.
, and
Presser
,
V.
,
2014
, “
Polyvinylpyrrolidone as Binder for Castable Supercapacitor Electrodes With High Electrochemical Performance in Organic Electrolytes
,”
J. Power Sources
,
266
, pp.
374
383
.
8.
Shah
,
S. I. U.
,
Hector
,
A. L.
, and
Owen
,
J. R.
,
2014
, “
Redox Supercapacitor Performance of Nanocrystalline Molybdenum Nitrides Obtained by Ammonolysis of Chloride- and Amide-Derived Precursors
,”
J. Power Sources
,
266
, pp.
456
463
.
9.
Hong
,
W.
,
Wang
,
J.
,
Niu
,
L.
,
Sun
,
J.
,
Gong
,
P.
, and
Yang
,
S.
,
2014
, “
Controllable Synthesis of CoAl LDH@Ni(OH)2 Nanosheet Arrays as Binder-Free Electrode for Supercapacitor Applications
,”
J. Alloys Compd.
,
608
, pp.
297
303
.
10.
Dyatkin
,
B.
,
Presser
,
V.
,
Heon
,
M.
,
Lukatskaya
,
M. R.
,
Beidaghi
,
M.
, and
Gogotsi
,
Y.
,
2013
, “
Development of a Green Supercapacitor Composed Entirely of Environmentally Friendly Materials
,”
ChemSusChem
,
6
(
12
), pp.
2269
2280
.
11.
Gao
,
Y.
,
Presser
,
V.
,
Zhang
,
L.
,
Niu
,
J. J.
,
McDonough
,
J. K.
,
Perez
,
C. R.
,
Lin
,
H.
,
Fong
,
H.
, and
Gogotsi
,
Y.
,
2012
, “
High Power Supercapacitor Electrodes Based on Flexible TiC-CDC Nano-Felts
,”
J. Power Sources
,
201
, pp.
368
375
.
12.
Fu
,
C.
,
Kuang
,
Y.
,
Huang
,
Z.
,
Wang
,
X.
,
Yin
,
Y.
,
Chen
,
J.
, and
Zhou
,
H.
,
2011
, “
Supercapacitor Based on Graphene and Ionic Liquid Electrolyte
,”
J. Solid State Electrochem.
,
15
(
11–12
), pp.
2581
2585
.
13.
Tamailarasan
,
P.
, and
Ramaprabhu
,
S.
,
2012
, “
Carbon Nanotubes-Graphene-Solidlike Ionic Liquid Layer-Based Hybrid Electrode Material for High Performance Supercapacitor
,”
J. Phys. Chem. C
,
116
(
27
), pp.
14179
14187
.
14.
Lu
,
W.
,
Qu
,
L.
,
Henry
,
K.
, and
Dai
,
L.
,
2009
, “
High Performance Electrochemical Capacitors From Aligned Carbon Nanotube Electrodes and Ionic Liquid Electrolytes
,”
J. Power Sources
,
189
(
2
), pp.
1270
1277
.
15.
Kotz
,
R.
, and
Carlen
,
M.
,
2000
, “
Principles and Applications of Electrochemical Capacitors
,”
Electrochim. Acta
,
45
(
15–16
), pp.
2483
2498
.
16.
Abadi
,
P. P. S. S.
,
Maschmann
,
M. R.
,
Mortuza
,
S. M.
,
Banerjee
,
S.
,
Baur
,
J. W.
,
Graham
,
S.
, and
Cola
,
B. A.
,
2014
, “
Reversible Tailoring of Mechanical Properties of Carbon Nanotube Forests by Immersing in Solvents
,”
Carbon
,
69
, pp.
178
187
.
17.
In
,
H. J.
,
Kumar
,
S.
,
Shao-Horn
,
Y.
, and
Barbastathis
,
G.
,
2006
, “
Origami Fabrication of Nanostructured, Three-Dimensional Devices: Electrochemical Capacitors With Carbon Electrodes
,”
Appl. Phys. Lett.
,
88
(
8
), p.
083104
.
18.
Chen
,
P.-C.
,
Shen
,
G.
,
Sukcharoenchoke
,
S.
, and
Zhou
,
C.
,
2009
, “
Flexible and Transparent Supercapacitor Based on In2O3 Nanowire/Carbon Nanotube Heterogeneous Films
,”
Appl. Phys. Lett.
,
94
(
4
), p.
043113
.
19.
Zhou
,
R.
,
Meng
,
C.
,
Zhu
,
F.
,
Li
,
Q.
,
Liu
,
C.
,
Fan
,
S.
, and
Jiang
,
K.
,
2010
, “
High-Performance Supercapacitors Using a Nanoporous Current Collector Made From Super-Aligned Carbon Nanotubes
,”
Nanotechnology
,
21
(
34
), p.
345701
.
20.
Chen
,
T.
,
Peng
,
H.
,
Durstock
,
M.
, and
Dai
,
L.
,
2014
, “
High-Performance Transparent and Stretchable All-Solid Supercapacitors Based on Highly Aligned Carbon Nanotube Sheets
,”
Sci. Rep.
,
4
(
1
), p.
3612
.
21.
Yu
,
D.
,
Goh
,
K.
,
Wang
,
H.
,
Wei
,
L.
,
Jiang
,
W.
,
Zhang
,
Q.
,
Dai
,
L.
, and
Chen
,
Y.
,
2014
, “
Scalable Synthesis of Hierarchically Structured Carbon Nanotube-Graphene Fibres for Capacitive Energy Storage
,”
Nat. Nanotechnol.
,
9
(
7
), pp.
555
562
.
22.
Candelaria
,
S. L.
,
Shao
,
Y.
,
Zhou
,
W.
,
Li
,
X.
,
Xiao
,
J.
,
Zhang
,
J.-G.
,
Wang
,
Y.
,
Liu
,
J.
,
Li
,
J.
, and
Cao
,
G.
,
2012
, “
Nanostructured Carbon for Energy Storage and Conversion
,”
Nano Energy
,
1
(
2
), pp.
195
220
.
23.
An
,
K. H.
,
Kim
,
W. S.
,
Park
,
Y. S.
,
Moon
,
J. M.
,
Bae
,
D. J.
,
Lim
,
S. C.
,
Lee
,
Y. S.
, and
Lee
,
Y. H.
,
2001
, “
Electrochemical Properties of High-Power Supercapacitors Using Single-Walled Carbon Nanotube Electrodes
,”
Adv. Funct. Mater.
,
11
(
5
), pp.
387
392
.
24.
Ma
,
R. Z.
,
Liang
,
J.
,
Wei
,
B. Q.
,
Zhang
,
B.
,
Xu
,
C. L.
, and
Wu
,
D. H.
,
1999
, “
Study of Electrochemical Capacitors Utilizing Carbon Nanotube Electrodes
,”
J. Power Sources
,
84
(
1
), pp.
126
129
.
25.
Niu
,
C. M.
,
Sichel
,
E. K.
,
Hoch
,
R.
,
Moy
,
D.
, and
Tennent
,
H.
,
1997
, “
High Power Electrochemical Capacitors Based on Carbon Nanotube Electrodes
,”
Appl. Phys. Lett.
,
70
(
11
), pp.
1480
1482
.
26.
Frackowiak
,
E.
,
Metenier
,
K.
,
Pellenq
,
R.
,
Bonnamy
,
S.
, and
Beguin
,
F.
,
1999
, “
Capacitance Properties of Carbon Nanotubes
,”
13th International Winterschool on Electronic Properties of Novel Materials
(IWEPNM), Kirchberg, Austria, Feb. 27–Mar. 6, pp.
429
432
.
27.
Diederich
,
L.
,
Barborini
,
E.
,
Piseri
,
P.
,
Podesta
,
A.
,
Milani
,
P.
,
Schneuwly
,
A.
, and
Gallay
,
R.
,
1999
, “
Supercapacitors Based on Nanostructured Carbon Electrodes Grown by Cluster-Beam Deposition
,”
Appl. Phys. Lett.
,
75
(
17
), pp.
2662
2664
.
28.
An
,
K. H.
,
Jeon
,
K. K.
,
Heo
,
J. K.
,
Lim
,
S. C.
,
Bae
,
D. J.
, and
Lee
,
Y. H.
,
2002
, “
High-Capacitance Supercapacitor Using a Nanocomposite Electrode of Single-Walled Carbon Nanotube and Polypyrrole
,”
J. Electrochem. Soc.
,
149
(
8
), pp.
A1058
A1062
.
29.
Zhang
,
H.
,
Cao
,
G.
,
Yang
,
Y.
, and
Gu
,
Z.
,
2008
, “
Comparison Between Electrochemical Properties of Aligned Carbon Nanotube Array and Entangled Carbon Nanotube Electrodes
,”
J. Electrochem. Soc.
,
155
(
2
), pp.
K19
K22
.
30.
Brandt
,
A.
,
Pohlmann
,
S.
,
Varzi
,
A.
,
Balducci
,
A.
, and
Passerini
,
S.
,
2013
, “
Ionic Liquids in Supercapacitors
,”
MRS Bull.
,
38
(
7
), pp.
554
559
.
31.
Shim
,
Y.
, and
Kim
,
H. J.
,
2010
, “
Nanoporous Carbon Supercapacitors in an Ionic Liquid: A Computer Simulation Study
,”
ACS Nano
,
4
(
4
), pp.
2345
2355
.
32.
Pak
,
A. J.
,
Paekw
,
E.
, and
Hwang
,
G. S.
,
2013
, “
Relative Contributions of Quantum and Double Layer Capacitance to the Supercapacitor Performance of Carbon Nanotubes in an Ionic Liquid
,”
Phys. Chem. Chem. Phys.
,
15
(
45
), pp.
19741
19747
.
33.
Shim
,
Y.
,
Jung
,
Y.
, and
Kim
,
H. J.
,
2011
, “
Graphene-Based Supercapacitors: A Computer Simulation Study
,”
J. Phys. Chem. C
,
115
(
47
), pp.
23574
23583
.
34.
Mostafa
,
M.
, and
Banerjee
,
S.
,
2014
, “
Effect of Functional Group Topology of Carbon Nanotubes on Electrophoretic Alignment and Properties of Deposited Layer
,”
J. Phys. Chem. C
,
118
(
21
), pp.
11417
11425
.
35.
Mostafa
,
M.
, and
Banerjee
,
S.
,
2014
, “
Predictive Model for Alignment and Deposition of Functionalized Nanotubes Using Applied Electric Field
,”
J. Appl. Phys.
,
115
(
24
), p.
244309
.
36.
Yang
,
L.
,
Fishbine
,
B. H.
,
Migliori
,
A.
, and
Pratt
,
L. R.
,
2009
, “
Molecular Simulation of Electric Double-Layer Capacitors Based on Carbon Nanotube Forests
,”
J. Am. Chem. Soc.
,
131
(
34
), pp.
12373
12376
.
37.
Plimpton
,
S.
,
1995
, “
Fast Parallel Algorithms for Short-Range Molecular-Dynamics
,”
J. Comput. Phys.
,
117
(
1
), pp.
1
19
.
38.
Jorgensen
,
W. L.
, and
Tiradorives
,
J.
,
1988
, “
The OPLS Potential Functions for Proteins—Energy Minimizations for Crystals of Cyclic-Peptides and Crambin
,”
J. Am. Chem. Soc.
,
110
(
6
), pp.
1657
1666
.
39.
Jorgensen
,
W. L.
,
Maxwell
,
D. S.
, and
TiradoRives
,
J.
,
1996
, “
Development and Testing of the OPLS All-Atom Force Field on Conformational Energetics and Properties of Organic Liquids
,”
J. Am. Chem. Soc.
,
118
(
45
), pp.
11225
11236
.
40.
Deshpande
,
A.
,
Kariyawasam
,
L.
,
Dutta
,
P.
, and
Banerjee
,
S.
,
2013
, “
Enhancement of Lithium Ion Mobility in Ionic Liquid Electrolytes in Presence of Additives
,”
J. Phys. Chem. C
,
117
(
48
), pp.
25343
25351
.
41.
Nose
,
S.
, and
Klein
,
M. L.
,
1983
, “
Constant Pressure Molecular-Dynamics for Molecular-Systems
,”
Mol. Phys.
,
50
(
5
), pp.
1055
1076
.
42.
Nose
,
S.
,
1984
, “
A Unified Formulation of the Constant Temperature Molecular-Dynamics Methods
,”
J. Chem. Phys.
,
81
(
1
), pp.
511
519
.
43.
Pilon
,
L.
,
Wang
,
H.
, and
d'Entremont
,
A.
,
2015
, “
Recent Advances in Continuum Modeling of Interfacial and Transport Phenomena in Electric Double Layer Capacitors
,”
J. Electrochem. Soc.
,
162
(
5
), pp.
A5158
A5178
.
44.
Borodin
,
O.
, and
Smith
,
G. D.
,
2006
, “
Structure and Dynamics of N-Methyl-N-Propylpyrrolidinium Bis(Trifluoromethanesulfonyl)Imide Ionic Liquid From Molecular Dynamics Simulations
,”
J. Phys. Chem. B
,
110
(
23
), pp.
11481
11490
.
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