Physicochemical Properties of Three Ionic Liquids Containing a Tetracyanoborate Anion and Their Lithium Salt Mixtures

Abstract

Given their relevant physicochemical properties, ionic liquids (ILs) are attracting great attention as electrolytes for use in different electrochemical devices, such as capacitors, sensors, and lithium ion batteries. In addition to the advantages of using ILs containing lithium cations as electrolytes in lithium ion batteries, the Li(+) transport in ILs containing the most common anion, bis(trifluoromethanesulfonyl) imide anion ([Tf2N]), is reportedly small; therefore, its contribution to the overall conductivity is also low. In this work, we describe the preparation and characterization of two new and one known IL containing the tetracyanoborate anion ([B(CN)4]) as the anionic species. These ILs have high thermal and chemical stabilities, with almost twice the ionic conductivity of the [Tf2N] ILs and, most importantly, provide a greater role for the Li(+) ion throughout the conductivity process. The experimental ionic conductivity and self-diffusion coefficient data show that the [B(CN)4]-based ILs and their Li(+) mixtures have a higher number of charge carriers. Molecular dynamics simulations showed a weaker interaction between Li(+) and [B(CN)4] than that with [Tf2N]. These results may stimulate new applications for ILs that have good Li(+) transport properties.

Cyanohydridoborate Anions: Synthesis, Salts, and Low‐Viscosity Ionic Liquids

“…Selectedcalculated bond parameters [a] and calculated as well as experimental and calculated spectroscopicp roperties of 1-5. [b-d] [B(CN) 4 [8] [h] Additionalm easurements in the presence of glass powder as crystallization initiator did neither result in the observationo fc rystallization,c old crystallization nor melting.…”

“…[1,38] [c]Literature valuesf or [EMIm]4 at 25 8C: h = 19 mPa sa nd 1 = 0.98 gcm -3 . [39] Literaturev alues for [BMPL]1 at 25 8C: h = 48.0 mPa s, 1 = 0.98 gcm -3 , D + = 2.4 10 À11 m 2 ·s À1 , D À = 2.5 10 À11 m 2 ·s À1 , s = 6.9 mS cm À1 , DE = 4.8 V. [8] [e] n.d. = not determined. The specificc onductivity of all ILs described herein increases with increasing temperature as shown in Figure 4.…”

“…1-Butyl-1-methylpyrrolidinium tetracyanoborate( [BMPL]1)isafurther example for an TCB-IL that has appealingp roperties. [7,8] The outstandingproperties,i nparticular the low viscosity of TCB-RTILs make them materials of choice for example as component of electrolytes and as counteranionso fc obalt-based redox-couples in dye-sensitized solar cells (DSSCs, Grätzel cells). [9] Recently,w eh ave demonstrated that the viscosity of cyanoborate-ILs can be reduced by lowering the symmetry of the anion and by diminishing the anion molar mass.…”

Improved Performance of Ionic Liquid Supercapacitors by using Tetracyanoborate Anions

“…Moreover, [B(CN) 4 ] anions may undergo polymerization at high overpotentials, thereby acting as a safety mechanism . ILs containing [B(CN) 4 ] anions are known to possess a wide electrochemical stability window when an inert electrode material, (such as glassy carbon) is employed. However, it is important to determine an ILs stability when combined with the activated carbon material used in EDLC electrodes, which presents much higher surface area and can catalytically decrease the ILs electrochemical stability.…”

“…However, it is important to determine an ILs stability when combined with the activated carbon material used in EDLC electrodes, which presents much higher surface area and can catalytically decrease the ILs electrochemical stability. In this work, we present the results of EDLCs containing two ILs based on tetracyanoborate anions: N ‐butyl‐ N ‐methylpiperidinium ([Pip 1,4 ][B(CN) 4 ]) and [Pyr 1,4 ][B(CN) 4 ], shown in Figure a (the physicochemical characteristics of these ILs are described elsewhere).…”