Nanoporous Carbon Supercapacitors in an Ionic Liquid: A Computer Simulation Study

被引:255
作者
Shim, Youngseon [1 ,2 ]
Kim, Hyung J. [1 ,3 ]
机构
[1] Carnegie Mellon Univ, Dept Chem, Pittsburgh, PA 15213 USA
[2] Seoul Natl Univ, Dept Chem, Seoul 151747, South Korea
[3] Korea Inst Adv Study, Sch Computat Sci, Seoul 130722, South Korea
基金
新加坡国家研究基金会; 美国国家科学基金会;
关键词
supercapacitor; electric double layer; ionic liquid; imidazolium ion; carbon nanotube; micropore; molecular dynamics simulations; specific capacitance; ELECTRON-TRANSFER REACTIONS; DOUBLE-LAYER; DIFFERENTIAL CAPACITANCE; SOLVATION DYNAMICS; RELAXATION; ENERGY; MODEL; WATER; SIZE; WALL;
D O I
10.1021/nn901916m
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
Supercapacitors composed of carbon nanotube (CNT) micropores in the room-temperature ionic liquid (RTIL) 1-ethyl-3-methylimidazolium tetrafluoroborate (EMI+BF4-) are studied via molecular dynamics (MD) computer simulations. It is found that the distribution of RTIL ions inside the micropore varies significantly with the pore size. Internal solvation of small (6,6) and (7,7) CNTs with an electrified interior wall is effected almost exclusively via counterions. Surprisingly, these counterions, even though they all have the same charge, lead to a charge density characterized by multiple layers with alternating signs. This intriguing feature is attributed to the extended nature of RTIL ion charge distributions, which result in charge separation through preferential orientation inside the electrified nanotubes. In the case of larger (10,10) and (15,15) CNTs, counterions and co-ions develop multilayer solvation structures. The specific capacitance normalized to the pore surface area is found to increase as the CNT diameter decreases from (15,15) to (7,7). As the pore site further reduces from (6,6)10 (5,5), however, the specific capacitance diminishes rapidly. These findings are in excellent agreement with recent experiments with carbon-based materials. A theoretical model based on multiple charge layers is proposed to understand both the MD and experimental results.
引用
收藏
页码:2345 / 2355
页数:11
相关论文
共 51 条
[1]   Capacitance Measurements in a Series of Room-Temperature Ionic Liquids at Glassy Carbon and Gold Electrode Interfaces [J].
Alam, Muhammad Tanzirul ;
Islam, Md. Mominul ;
Okajima, Takeyoshi ;
Ohsaka, Takeo .
JOURNAL OF PHYSICAL CHEMISTRY C, 2008, 112 (42) :16600-16608
[2]   Controlling the Outcome of Electron Transfer Reactions in Ionic Liquids [J].
Annapureddy, Harsha V. R. ;
Margulis, Claudio J. .
JOURNAL OF PHYSICAL CHEMISTRY B, 2009, 113 (35) :12005-12012
[3]  
[Anonymous], 1999, ELECTROCHEMICAL SUPE
[4]   Hydrophobic, highly conductive ambient-temperature molten salts [J].
Bonhote, P ;
Dias, AP ;
Papageorgiou, N ;
Kalyanasundaram, K ;
Gratzel, M .
INORGANIC CHEMISTRY, 1996, 35 (05) :1168-1178
[5]   Spectroscopic and dielectric properties of liquid water: A molecular dynamics simulation study [J].
Bursulaya, BD ;
Kim, HJ .
JOURNAL OF CHEMICAL PHYSICS, 1998, 109 (12) :4911-4919
[6]  
Chmiola J, 2006, SCIENCE, V313, P1760, DOI 10.1126/science/1132195
[7]   The role and utilization of pseudocapacitance for energy storage by supercapacitors [J].
Conway, BE ;
Birss, V ;
Wojtowicz, J .
JOURNAL OF POWER SOURCES, 1997, 66 (1-2) :1-14
[8]   Dielectric response of imidazolium-based room-temperature ionic liquids [J].
Daguenet, Corinne ;
Dyson, Paul J. ;
Krossing, Ingo ;
Oleinikova, Alla ;
Slattery, John ;
Wakai, Chihiro ;
Weingaertner, Hermann .
JOURNAL OF PHYSICAL CHEMISTRY B, 2006, 110 (25) :12682-12688
[9]   Computational study of room temperature molten salts composed by 1-alkyl-3-methylimidazolium cations-force-field proposal and validation [J].
de Andrade, J ;
Böes, ES ;
Stassen, H .
JOURNAL OF PHYSICAL CHEMISTRY B, 2002, 106 (51) :13344-13351
[10]   Ionic liquid near a charged wall: Structure and capacitance of electrical double layer [J].
Fedorov, Maxim V. ;
Kornyshev, Alexei A. .
JOURNAL OF PHYSICAL CHEMISTRY B, 2008, 112 (38) :11868-11872