Ether-Bond-Containing Ionic Liquids and the Relevance of the Ether Bond Position to Transport Properties

Monteiro, Marcelo José; Camilo, Fernanda F.; Ribeiro, Mauro C. C.; Torresi, Roberto M.

doi:10.1021/jp104419k

Cited by 85 publications

(85 citation statements)

References 29 publications

(58 reference statements)

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“…Another excellent example was illustrated by Donato et al [ 50 ] as: [Me(OCH 2 CH 2 ) 3 25 °C). The same conductivity increase trend was observed for ether-functionalized ILs based on imidazolium cations [ 38 ], pyrrolidinium, piperidinium, oxazolidinium, or morpholinium cations [ 24 ], phosphonium and ammonium cations [ 25 , 51 , 52 ], as well as guanidinium cations [ 53 , 54 ]. Belhocine et al [ 55 ] prepared a series of seven-member ring azepanium-based ILs (Scheme 8.1 ) and found the incorporation of alkoxyalkyl group results in a reduction in viscosities and an increase in conductivities.…”

Section: Electrochemical Propertiessupporting

confidence: 60%

Task-Specific Ionic Liquids for Electrochemical Applications

Zhao

2015

Electrochemistry in Ionic Liquids

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Ionic liquids (ILs) have been widely examined as solvents, additives, or catalysts in a variety of applications including organic catalysis [ 1 -5 ], inorganic and materials synthesis [ 6 ], biocatalysis [ 7 -12 ], electrochemistry [ 13 ], pharmaceutical chemistry [ 14 ], polymerization [ 15 , 16 ], and engineering fl uids [ 17 -19 ]. The physicochemical properties of ILs are tunable through a careful selection of a variety of different cations and anions and a rational combination of ion pairs. More interestingly, cations and/or anions can be further functionalized to form so-called task-specifi c ionic liquids (TSILs). The notion of TSILs carrying specifi c functionality tailored for particular applications has proven visionary, and a variety of different functional groups have been grafted onto ILs [ 20 -22 ]. In particular, there is an exponential growth in constructing new TSILs as electrolytes for electrochemical applications. This chapter focuses on a critical discussion of some major types of TSILs and their electrochemical properties and applications. Ether/Thioether-and Hydroxyl/Thiol-Functionalized ILs General Physical PropertiesOur recent review has captured some key physical properties of ether-and alcoholfunctionalized ILs [ 22 ]. The inclusion of alkyloxy or alkyloxyalkyl groups in ILs often lowers the melting points ( T m ) [ 23 -26 ]. Additionally, the lowering of the

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Section: Electrochemical Propertiessupporting

confidence: 60%

Task-Specific Ionic Liquids for Electrochemical Applications

Zhao

2015

Electrochemistry in Ionic Liquids

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“…[176] However,t here are some major challenges concerning the utilization of ILs for lithium battery applications, such as their relativelyl ower ionic conductivity at ambient temperature compared with organic-solvent-based electrolytes and, in some cases,t heir incompatibility with commonly employed active materials, such as graphite. Very promising resultst argeting the improvement in lithium-ion transport and an enhanced compatibilityw ith standard electrode materials were obtained, among other things, by mixing different ILs; [178][179][180][181] adding functional organic compounds (e.g.,V C, EC, or chloroethylene carbonate); [179,[182][183][184][185][186][187] or designing functionalized ILs, including asymmetricala nions [101,[188][189][190][191][192][193] or ether/ester groups, [101,[194][195][196][197] as well as cyano groups. [198] The incorporation of an oxygen atom into the aliphatic side chain, for instance, resultedi nasignificantly decreased melting temperature and enhanced ionic conductivity, which was attributed to reduced crystal packing of the ions.…”

Section: Il-based Electrolytesmentioning

confidence: 99%

Safer Electrolytes for Lithium‐Ion Batteries: State of the Art and Perspectives

et al. 2015

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Lithium-ion batteries are becoming increasingly important for electrifying the modern transportation system and, thus, hold the promise to enable sustainable mobility in the future. However, their large-scale application is hindered by severe safety concerns when the cells are exposed to mechanical, thermal, or electrical abuse conditions. These safety issues are intrinsically related to their superior energy density, combined with the (present) utilization of highly volatile and flammable organic-solvent-based electrolytes. Herein, state-of-the-art electrolyte systems and potential alternatives are briefly surveyed, with a particular focus on their (inherent) safety characteristics. The challenges, which so far prevent the widespread replacement of organic carbonate-based electrolytes with LiPF6 as the conducting salt, are also reviewed herein. Starting from rather "facile" electrolyte modifications by (partially) replacing the organic solvent or lithium salt and/or the addition of functional electrolyte additives, conceptually new electrolyte systems, including ionic liquids, solvent-free, and/or gelled polymer-based electrolytes, as well as solid-state electrolytes, are also considered. Indeed, the opportunities for designing new electrolytes appear to be almost infinite, which certainly complicates strict classification of such systems and a fundamental understanding of their properties. Nevertheless, these innumerable opportunities also provide a great chance of developing highly functionalized, new electrolyte systems, which may overcome the afore-mentioned safety concerns, while also offering enhanced mechanical, thermal, physicochemical, and electrochemical performance.

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“…20 The physical properties of ILs, in particular the viscosity/conductivity, can be altered through the inclusion of ether linkages in the alkyl side chains of cations . 33 It has been proposed that the inclusion of ether bonds results in increased specific capacitances in EDLCs using mesoporous carbon electrodes by adding a degree of flexibility into the anion and alteration of the charge density. 34 Therefore to explore As a substantial number of reports have shown that the pore characteristics of electrodes strongly influence the performance of EDLCs, 22,28,[35][36][37][38] we also compare 30 the behaviour of these ILs when combined with electrodes of differing average pore size (d) in the small mesopore range (i.e.…”

Section: Introductionmentioning

confidence: 99%

“…23 Viscosities determined for each of the ILs in this work are given in Table 1 33,34 ). Electron donation from the oxygen atom diminishes the charge of the cation resulting in weaker anion-cation interactions.…”

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confidence: 99%

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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Ether-Bond-Containing Ionic Liquids and the Relevance of the Ether Bond Position to Transport Properties

Cited by 85 publications

References 29 publications

Task-Specific Ionic Liquids for Electrochemical Applications

Task-Specific Ionic Liquids for Electrochemical Applications

Safer Electrolytes for Lithium‐Ion Batteries: State of the Art and Perspectives

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

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