Functionalized Ionic Liquids Based on Trialkylimidazolium Cations with Alkoxymethyl Group at the N-1 Position: Synthesis, Characterization, and Application as Electrolytes for a Lithium Ion Battery

Abstract

Twenty-four new functionalized ionic liquids (ILs) based on trialkylimidazolium cations with the alkoxymethyl group at the N-1 position were synthesized and characterized. Physicochemical properties of these ILs, such as melting point, thermal stability, density, viscosity, conductivity, and electrochemical stability, were studied systematically. Twenty-one ILs appeared in the liquid state at room temperature, and 14 ILs showed a melting point lower than −60 °C. Introduction of the alkoxymethyl group at the N-1 position of trialkylimidazolium cations could not be more beneficial than that of the alkoxyethyl group for reducing viscosity. Li/LiFePO 4 cells employing three trialkylimidazolium ILs with methoxymethyl-group-based electrolytes showed good discharge capacity and cycle stability at a current rate of 0.1 C. This is the first report of ILs with the alkoxymethyl group used as electrolytes without an additive for a lithium ion battery.

Comparative Study of Physical Properties and CO2 Solubility of Ammonium and Sulfonium Ionic Liquids in Mixture with Glutaronitrile

“…Mixtures of ILs with protic molecular solvents such as water, alcohols, amides, and so forth ,, or aprotic solvents such as ACN, alkylcarbonates, DMSO, or DMF , improve the properties of ILs by lowering their viscosity and promoting ionic dissociations while retaining their thermal and electrochemical properties, unlike mineral salts, whose solubility in molecular solvents is often limited (close to 1–2 mol L –1 ) . ILs often composed of asymmetrical organic cations are much more soluble or miscible in all proportions. ,, The cross-interactions between ion liquid ions and molecular solvent molecules depend on several factors: the presence of a labile proton, the size of ions, the nature of the heteroatom (S, N, P) in the cation (sulfonium, ammonium, or phosphonium), , the length of the carbon chain of the cation or anion, , and also the properties of the molecular solvent chosen to make the mixture. , Among the solvents suitable for electrochemical applications, nitriles and more specifically dinitriles , have emerged as a base for electrolytes for batteries, , supercapacitors, and other energy storage applications. , Among dinitriles, glutaronitrile (GLN) is emerging as an electrochemically stable and safe solvent very suitable for various applications − …”

Effect of mixed anions on the transport properties and performance of an ionic liquid-based electrolyte for lithium-ion batteries

“…Furthermore, Li[TFSI] offers many advantages, such as a higher solubility in many solvents (including ILs), driven by a lower lattice energy than the benchmarks Li[PF 6 ] or Li [BF 4 ] [18]. Therefore, many studies investigating the use of IL-Li[TFSI] mixtures as electrolytes for Li-batteries have been reported [19][20][21][22][23][24]. However, only a few studies have been conducted by mixing salts to yield both [FSI] − and [TFSI] − anions in solution.…”

Effect of Anion and Alkyl Side Chain on Structural and Dynamic Features of Ester Functionalized Ionic Liquids: Confirming Nanoscale Organization

“…Recently, ester-functionalized ILs with an ester group (−COO−) introduced to the alkyl side chain of imidazolium ILs have been synthesized and investigated experimentally. − The reported results show that the incorporation of the ester group brings about remarkable enhancement of the biodegradability of ILs. Also, this class of ILs has been recently applied as electrolytes for the lithium ion battery. − With regard to the substantial influences of negligible amounts of water and the other organic impurities on thermodynamic, structural, and dynamic properties of these ILs, a few experimental data of mentioned properties are available. Hence, the main aim of the present work is to investigate the structural and dynamic properties of ester functionalized ILs composed of 3-methyl-1-[(methoxycarbonyl)­methyl]­imidazolium ([C 1 COOC 1 C 1 im] + ), 3-methyl-1-[(ethoxycarbonyl)­methyl]­imidazolium ([C 1 COOC 2 C 1 im] + ), and 3-methyl-1-[(buthoxycarbonyl)­methyl]­imidazolium ([C 1 COOC 4 C 1 im] + ) cation combined with [Br] − , [NO 3 ] − , [BF 4 ] − , [PF 6 ] − , [TfO] − , and [Tf 2 N] − anions by means of MD simulations.…”