Electrochemical Properties of Imidazolium Salt Electrolytes for Electrochemical Capacitor Applications

McEwen, Alan B.; Ngo, Helen L.; LeCompte, Karen A.; Goldman, J. L.

doi:10.1149/1.1391827

Cited by 846 publications

(625 citation statements)

References 18 publications

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“…17,23,[26][27][28] Imidazolium [Tf 2 N] electrolytes, on the other hand, tend to be less viscous at room temperature but are less electrochemically stable and are limited to operating potentials around 3.2V. 17,20,23,29,30 For example, the conductivity of 1-butyl-3-methylpyrrolidinum [Tf 2 N] is in the region of 2.2mScm -1 24 whereas 1-ethyl-3-methylimidazoium [Tf 2 N] is 3.4mScm -1 . 29 There is 10 therefore a compromise between the quantity of energy stored in an IL based EDLC and the rate at which this energy can be delivered.…”

Section: Introductionmentioning

confidence: 99%

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Ionic liquid based EDLCs: influence of carbon porosity on electrochemical performance

2014

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Electrochemical double layer capacitors (EDLCs) are a category of supercapacitors; devices that store charge at the interface between electrodes and an electrolyte. Currently available commercial devices have a limited operating potential that restricts their energy and power densities. Ionic liquids (ILs) are a promising alternative electrolyte as they generally exhibit greater electrochemical stabilities and lower volatility. This work investigates the electrochemical performance of EDLCs using ILs that combine the bis(trifluoromethanesulfonyl)imide anion with sulfonium and ammonium based cations. Different activated carbon materials were employed to also investigate the influence of varying pore size on electrochemical performance. Electrochemical impedance spectroscopy (EIS) and constant current cycling at different rates were used to assess resistance and specific capacitance. In general, greater specific capacitances and lower resistances were found with the sulfonium based ILs studied, and this was attributed to their smaller cation volume. Comparing electrochemical stabilities indicated that significantly higher operating potentials are possible with the ammonium based ILs. The marginally smaller sulfonium cation performed better with the carbon exhibiting the largest pore width, whereas peak performance of the larger sulfonium cation was associated with a narrower pore size. Considerable differences between the performance of the ammonium based ILs were observed and attributed to differences not only in cation size but also due to the inclusion of a methoxyethyl group. The improved performance of the ether bond containing IL was ascribed to electron donation from the oxygen atom influencing the charge density of the cation and facilitating cation–cation interactions.

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Section: Introductionmentioning

confidence: 99%

“…17,20,23,29,30 For example, the conductivity of 1-butyl-3-methylpyrrolidinum [Tf 2 N] is in the region of 2.2mScm -1 24 whereas 1-ethyl-3-methylimidazoium [Tf 2 N] is 3.4mScm -1 . 29 There is 10 therefore a compromise between the quantity of energy stored in an IL based EDLC and the rate at which this energy can be delivered.…”

Section: Introductionmentioning

confidence: 99%

Ionic liquid based EDLCs: influence of carbon porosity on electrochemical performance

2014

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“…In particular, electrochemical devices utilizing RTILs are strongly expected as those of high-energy density with high safety [3]. For instance, lithium ion secondary batteries [4], high-performance electric double layer capacitors [5], dye-sensitised solar cells [6], field-effect transistors [7], electrochemical actuators [8] and fuel cells [9] using RTILs have been developed. However, for further development of such noble devices or new RTILs, the low viscosity of RTILs is one of the problems to overcome.…”

Section: Introductionmentioning

confidence: 99%

Liquid Structure and the Ion-Ion Interactions of Ethylammonium Nitrate Ionic Liquid Studied by Large Angle X-Ray Scattering and Molecular Dynamics Simulations

Umebayashi

Chung

Mitsugi

et al. 2008

J. Comput. Chem. Jpn.

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Room temperature ionic liquids (RTILs) are useful as new solvents or materials owing to their favorable properties such as negligible vapor pressure, non-flammability, and wide electrochemical window. For further development of new RTILs, it is indispensable to understand macroscopic properties as solvent and/or liquids of RTILs at a molecular or atomistic level. Here, liquid structure and the ion-ion interactions of room temperature ionic liquid ethylammonium nitrate (EAN) were studied by means of large angle X-ray scattering (LAXS) experiment and molecular dynamics simulations. X-ray interference function for EAN shows a small peak of 0.62Å -1 indicating nano-scale segregation in the ionic liquid. X-ray radial distribution function as the form of D(r) -4πr 2 ρ 0 evidently shows a peak of 3.4 and broad ones of 4.7, 8 and 12Å, suggesting that EAN has long range ordering in the liquid state. The intra-molecular X-ray interference function was estimated on the basis of molecular geometries found in crystals to yield the inter-molecular X-ray pair correlation function G LAXS inter (r). In G LAXS inter (r), peaks of 3.0, 3.4, and 4.7Å were found as the atom-atom correlation. The peak of 3.0Å can be assigned to the atom-atom correlation of N (C 2 H 5 NH 3 + ) O (NO 3 -) in the NH O hydrogen bonding. In addition, the peak of 3.4Å is also ascribable to C (C 2 H 5 NH 3 + ) O (NO 3 -) correlations in the CH O interactions. Molecular dynamics simulations based on newly developed force fields to describe a series of primary ammonium cation were performed to ascribe the peaks found in G LAXS inter (r). The X-ray interference function i MD (s) and the pair correlation function G MD (r) derived from simulations were reasonably in agreement with the experimental ones. According to the partial atom-atom correlation functions derived from the simulations, the experimentally observed peaks of 3.0 and 3.4Å can be ascribable to the NH O and the CH O correlations in the closest ethylammonium and nitrate interaction, respectively. The CH O interactions may play an important role in macroscopic properties of this kind of ionic liquids.

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“…8 Their low-volatility, high thermal stability and intrinsic conductivity make them potentially useful as electrolytes in gas sensors, 9 an application which will be discussed in more detail in section 5. RTILs are also used in a range of other electrochemical applications such as electrolytes in lithium batteries, 10 capacitors 11 and solar cells. 12 The electrochemical characteristics of RTILs have been more thoroughly discussed in a number of recent review papers.…”

Section: Introductionmentioning

confidence: 99%

The electrochemistry of simple inorganic molecules in room temperature ionic liquids

Silvester¹,

Rogers²,

Barrosse-Antle³

et al. 2008

J. Braz. Chem. Soc.

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A eletroquímica de compostos inorgânicos simples em líquidos iônicos a temperatura ambiente (RTIL) é revisada e alguns trabalhos novos nesta área são apresentados. Este artigo focaliza a comparação entre o comportamento eletroquímico em RTILs e em solventes apróticos convencionais. Alguns compostos (iodetos, O 2 , NO 2 , SO 2 , NH 3 ) apresentam reações e mecanismos similares em RTILs e em solventes apróticos (como é observado para compostos orgânicos). Entretanto, outras espécies (nitratos, PCl 3 , POCl 3 ) mostram comportamento excepcionalmente diferente em relação aos solventes tradicionais. Isto torna os RTILs um meio promissor para o estudo de compostos inorgânicos, e destaca a necessidade de maiores investigações nesta área.The electrochemistry of simple inorganic compounds in room temperature ionic liquids (RTILs) is reviewed and some new work in this area is presented. This paper focuses on the comparison between electrochemical behaviour in RTILs and in conventional aprotic solvents. Some compounds (iodides, O 2 , NO 2 , SO 2 , NH 3 ) display similar reactions and mechanisms in RTILs as in aprotic solvents (as is observed for organic compounds). However other species (nitrates, PCl 3 , POCl 3 ) show remarkably different behaviour to traditional solvents. This makes RTILs very promising media for the study of inorganic compounds, and highlights the need for more investigations in this exciting area.

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Electrochemical Properties of Imidazolium Salt Electrolytes for Electrochemical Capacitor Applications

Cited by 846 publications

References 18 publications

Ionic liquid based EDLCs: influence of carbon porosity on electrochemical performance

Ionic liquid based EDLCs: influence of carbon porosity on electrochemical performance

Liquid Structure and the Ion-Ion Interactions of Ethylammonium Nitrate Ionic Liquid Studied by Large Angle X-Ray Scattering and Molecular Dynamics Simulations

The electrochemistry of simple inorganic molecules in room temperature ionic liquids

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